The present invention relates to methods for repairing or recycling elastomeric films and in particular but not exclusively to repairing or recyding an elastomeric film using thermal re-processing. In addition, the invention relates to the use of a specific polymer latex to make an elastomeric film made from an aqueous dispersion of said polymer latex particles repairable and recydable and also to allow for self-healing of said films. Background of the invention

According to the present industry standard, elastomeric films, in particular tit dip-molding applications, for example examination gloves, are made from compounds containing carboxylated acrylonitrile butadiene latices (XNBR). In order to obtain the required mechanical strength for the purpose of use of these elastomeric films, some crosslinking of the films during the manufacturing of the elastomeric films needs to be achieved.

Several different concepts are available in the prior art in order to obtain such crosslinked elastomeric films. One possibility is that the compound fear making the elastomeric films contains a conventional sulfur vulcanization system such as sulfur in combination with accelerators, such as thiurams and carbamates and zinc oxide.

Since sulfur vulcanization systems might lead to allergic reactions, alternative concepts to make the latex film curable have been developed. Another possibility is to indude in the compound a crosslinker component like, for example polyvalent cation, for example zinc oxide or other poly-functional organic compounds suitable to react with functional groups on the latex particles in order to achieve chemical crossiinking. Furthermore, if the polymer latex bears sufficient amounts of self-crosslinking groups, for example N- methylol amide groups, suitor vulcanization systems and/or crosstinkers may be totally avoided.

All these different concepts lead to crossiinked elastomeric films, wherein the crosslinks are in essence irreversible so that that these elastomeric films cannot easily be recycled nor do they show any self-healing properties to make them repairable. For example, if any kind of defect such as pinholes occur during the manufacturing of the elastomeric film because of the lack of self-healing properties of the film, these products need to be scrapped, resulting in non-reusable waste, in addition, if such elastomeric films crack during their use, this cannot be repaired, resulting in an irreversible destruction of the elastomeric film and, thus, to failure of the article containing such elastomeric film.

Accordingly, there is a desire in the industry for elastomeric films that have inherent self- healing properties and can potentially be recycled in order to reduce the non-usable waste of such elastomeric films and to avoid final failure of articles comprising such elastomeric films.

WO 2017/209596 discloses a polymer latex for dip-molding applications comprising two different types of latex particles. One kind of latex particles is carboxylated whereas the second kind of latex particles contains oxira ne-functional groups.

Thus, the present invention seeks to provide a method for repairing or recycling an elastomeric film and to select a specific polymer latex for making an elastomeric film obtained from said polymer latex repairable and recyclable.

Summary of the invention

The present inventors have surprisingly found that an elastomeric film made from a polymer latex comprising:

(a) particles of a carboxyiated conjugated diene nitrile latex polymer (a) obtainable by free-radical emulsion polymerization of a mixture of ethy!enically unsaturated monomers comprising:

15 to 99 wt,-% of conjugated dienes;

1 to 80 wt-% of monomers selected from ethyienically unsaturated nitrile compounds;

0.05 to 10 wt.-% of ethyienically unsaturated carboxylic acids and/or salts thereof;

0 to 50 wt-% of vinyl aromatic monomers; and

0 to 65 wt.-% of alkyl esters of ethyienically unsaturated adds, the weight percentages being based on the total monomers in the mixture in combination or association with

(b) particles of a latex polymer (b) comprising at least one oxirane-functional group; wherein

the monomer composition of the latex polymer (a) is different from the monomer composition of the latex polymer (b) has self-healing properties and thus can be repaired and recycled. This was not possible before with sulfur vulcanized elastomeric films known from the prior art.

According to one aspect the present invention relates to a method for repairing an elastomeric film or an article comprising said elastomeric film by

a) providing a damaged elastomeric film or article comprising a damaged elastomeric film, the damaged elastomeric film having at least surfaces to be reconnected, b) re-joining the surfaces of the damaged film, and

c) heating or annealing the damaged elastomeric film while maintaining intimate contact of the rejoined surfaces of the damaged film at a temperature of 4G°C to 200°C, wherein

the elastomeric film is made from a polymer latex comprising:

(a) particles of a carboxyiated conjugated diene nitrile latex polymer (a) obtainable by free-radical emulsion polymerization of a mixture of ethylenicaliy unsaturated monomers comprising:

15 to 99 wt.-% of conjugated dienes;

1 to 80 wt.-% of monomers selected from eihylenicaHy unsaturated nitrite compounds;

¨ 0.05 to 10 wt.-% of ethylenica!!y unsaturated carboxylic acids and/or saits thereof;

0 to 50 wt-% of vinyl aromatic monomers; and

0 to 65 wt.-% of alkyl esters of ethyienicaliy unsaturated adds, the weight percentages being based on the total monomers in the mixture in combination or association with

(b) particles of a latex polymer (b) comprising at least one oxirene-functional group; wherein

the monomer composition of the latex polymer (a) is different from the monomer composition of the latex polymer (b). According to a further aspect the present invention relates to a method for recycling an elastomeric film or article comprising an elastomeric film by cutting, shredding or comminuting said elastomeric film or article to form particles of the elastomer, optionally blending the obtained particles with particles of virgin elastomer, and forming a recycled film or article by subjecting the particles to a pressure of 1 - 20 MPa and a temperature of 40X to 200°C, wherein the elastomeric film Is made from a polymer latex comprising;

(a) particles of a carboxylated conjugated diene nitrile latex polymer (a) obtainable by free-radical emulsion polymerization of a mixture of ethyienically unsaturated monomers comprising:

15 to 99 wt-% of conjugated dienes,

1 to 80 wt.-% of monomers selected from ethylenicaily unsaturated nitrile compounds;

0.05 to 10 wt.-% of ethylenicaily unsaturated carboxylic acids and/or salts thereof;

0 to 50 wt.-% of vinyl aromatic monomers; and

0 to 65 wt.-% of alkyl esters of ethylenicaily unsaturated adds, the weight percentages being based on the total monomers in the mixture in combination or association with

(b) particles of a latex polymer (b) comprising at least one oxirane-functionai group; wherein

the monomer composition of the latex polymer (a) is different from the monomer composition of the iatex polymer (b).

According to still a further aspect the present invention relates to the use of a polymer Iatex comprising;

(a) particles of a carboxyiated conjugated diene nitiile Iatex polymer (a) obtainable by free-radical emulsion polymerization of a mixture of ethylenicaily unsaturated monomers comprising:

- 15 to 99 wt-% of conjugated dienes;

1 to 80 wt-% of monomers selected from ethyienicaiiy unsaturated nitrile compounds;

0.05 to 10 wt.-% of ethylenicaily unsaturated carboxylic adds and/or salts thereof;

0 to 50 wt-% of vinyl aromatic monomers: and

0 to 65 wt-% of alkyl esters of ethyienicaiiy unsaturated adds, the weight percentages being based on the total monomers in the mixture in combination or association with

(b) particles of a latex polymer (b) comprising at least one oxirane-functionai group; wherein the monomer composition of the latex polymer (a) is different from tire monomer composition of the latex polymer (b)

to make an elastomeric film obtained from said polymer latex self-healing, repairable and/or recyclable,

Detailed description of toe invention

Polymer latex to be used to make an elastomeric film obtained therefrom self-healing, repairable and/or recvclable

The polymer latex to be used according to one aspect of the present invention to impart to an elastomeric film obtained therefrom self-healing properties to make said elastomeric film repairable and/or recyclable comprises:

(a) particles of a carboxylated conjugated diene nitrile latex polymer (a) obtainable by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers comprising:

15 to 99 wt-% of conjugated dienes;

1 to 80 wt-% of monomers selected from ethylenically unsaturated nitrile compounds;

0.05 to 10 wt.-% of ethylenically unsaturated carboxylic adds and/or salts thereof;

0 to 50 wt.-% of vinyl aromatic monomers; and

0 to 65 wt.-% of a!kyl esters of ethylenicaily unsaturated adds,

the weight percentages being based on the total monomers in toe mixture in combination or association with

(b) particles of a latex polymer (b) comprising at least one oxirane-functional group; wherein the monomer composition of the latex polymer (a) is different from toe monomer composition of the latex polymer (b). The term in combination or association covers a latex wherein the latex polymer (a) and the latex polymer (b) are present as a physical mixture such as a blend of both latex polymers as well as a latex wherein the latex polymer (a) and toe latex polymer (b) exhibit any kind of chemical or physical interaction between particles of latex polymer (a) and latex polymer (b). According to the present invention, combination or association of particles of said latex polymer (a) with particles of said latex polymer (b) can be achieved by for example one of toe following measures: (i) the mixture of ethylenicaily unsaturated monomers for latex polymer (a) is polymerized in presence of the oxirane-functionai latex particles (b) in the free- radical emulsion polymerization;

(ii) a polymer latex comprising the particles of latex polymer (a) and a polymer latex comprising the particles of latex polymer (b) are preformed and subsequently both lalices are combined; and

(iii) the mixture of ethyienically unsaturated monomers for latex polymer (a) is

polymerized in presence of the oxirane-functionai latex particles (b) in the free- radical emulsion polymerization forming a first polymer latex, and a second polymer latex comprising the particles of latex polymer (b) is preformed and subsequently both latices are combined, wherein the latex comprising the oxirane-functionai latex particles (b) present in the polymerization of the mixture of ethyienically unsaturated monomers for latex polymer (a) and the second polymer latex comprising the particles of component (b) are the same or are different.

The term * the monomer composition of the latex polymer (a) is different from the monomer composition of the latex polymer (b)” encompasses that the monomers used for the preparation of latex polymer (a) are different from the monomers for the preparation of latex polymer (b) or that the monomers are the same but are used in different relative amounts when preparing latex polymer (a) and latex polymer (b).

The polymer latex of the present invention may comprise:

(a) particles of a carboxyiated conjugated diene nitrile latex polymer (a) obtainable by free-radical emulsion polymerization of a mixture of ethyienically unsaturated monomers comprising:

15 to 99 wt.-% of conjugated denes;

1 to 80 wt.-% of monomers selected from ethyienically unsaturated nitrile compounds;

0.05 to 10 wt-% of ethyienically unsaturated carboxylic adds and/or salts thereof;

0 to 50 wt.-% of vinyl aromatic monomers; and

0 to 65 wt-% of alkyl esters of ethyienically unsaturated adds,

0 to 5 wt-%, preferably 0 to 3 wt.-% of ethyienically unsaturated monomers bearing an oxirane functional group

the weight percentages being based on the total monomers in the mixture for latex polymer a)

in combination or association with (b) particles of a latex polymer (b) obtainable by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers comprising more than 5 wt.-%, preferably at least 10 wt-% more preferred at least 15 wt -% of ethylenicaliy unsaturated monomers bearing an oxirane functional group based on the total monomers in the mixture for latex polymer b).

Latex polymer fbl comprisino at least one oxirane-functional oroup

The latex polymer (b) to be used according to the present invention can be prepared by any suitable free-radical emulsion polymerization process known in the art. Suitable process parameters are those that will be discussed below with respect to the emulsion polymerization process for the preparation of latex polymer (a).

The unsaturated monomers to be used for the preparation of the latex polymer (b) and their relative amounts are not particularly critical as long as the monomer mixture comprises at least one ethylenicaliy unsaturated monomer bearing an oxirane-functional group. According to the present invention the oxirane-functional ethylenicaliy unsaturated monomer may be monofunctionai with respect to the oxirane functionality and does not contain an oligomeric or polymeric backbone. Particularly, the number average molecular weight of the oxirane-functional ethylenicaliy unsaturated monomer is below 280 Dalton.

Suitable oxirane-functional ethylenicaliy unsaturated monomers may be selected from glytidyt (meth)acryiate, aliyt glyddylether, vinyl giytidyiether, vinyl cydohexene oxide, iimonene oxide, 2-ethylglyddylacrylate, 2-ethylglyddyimethacrylate. 2-{n- propyi)giyddylacrylate, 2-(n-propyl)g!ycidyimethacry}ate, 2-(n-butyl)gtyccidylacryiate, 2-(n- butyl)glycidyimethacrylate, glycidylmethylmethacrylate, glyddylacrylate, (3',4 - epoxyheptyf)-2-elhylacrylate, (3',4'-epoxyheptyi)~2~ethylmethacrylate, (6',7'- epoxyheptyf)acrylate, (6' , 7'~epoxyheptyl )methacrylate _f allyf-3,4-epoxyhepty}ether, 6,7- epoxyheptytallylether, vinyl-3, 4-epoxyheptylether, 3,4-epoxyheptylvinylether, 6,7- epoxyheptytvinyiether, o-vinylbenzylglycidyiether, m-vinyibenzylglycidylether, p- vinylbenzylglyddylether, 3-vinyi cydohexene oxide, alpha-methyl glycidyl methacrylate, 3,4~epoxycyck)hexylmethyl (meth)acrylate and combinations thereof. Glyddyl

(meth)acrylate is particularly preferred. The oxirane-functional latex polymer (b) according to the present invention may comprise structural units derived from ethylenicaliy unsaturated oxirane-functional monomers in an amount of 1 to 80 wt.-%, preferably 20 to 70 wt-%, more preferred 25 to 65 wt.-%, most preferred 35 to 65 wt-%, based on the total weight of monomers for the oxirane- functional latex particfes (b). Thus, the lower limit for the amount of ethytenicaiiy unsaturated oxirane-functional monomers may be 1 wt.-%, or 5 wt-%, or 10 wt-%, or 12 wt-%, or 14 wt-%, or 16 wt-%, or 18 wt-%, or 20 wt-%, or 22 wt-%, or 24 wt-%, or 26 wt-%, or 28 wt-%, or 30 wt-%, or 32 wt-%, or 34 wt-%, or 35 wt-%, based on the total weight of monomers for the oxirane-functional latex particles (b). Accordingly, the upper limit for the amount of ethylenicaily unsaturated oxirane-functional monomers may be 80 wt-%, or 75 wt.-%, or 73 wt.-%, or 70 wt-%, or 68 wt-%, or 65 wt-%, or 62 wt-%, or 60 wt-%, or 58 wt-%, or 56 wt-%, or 54 wt-%, or 52 wt-%, or 50 wt-%, based on toe total weight of monomers for the oxirane-functional latex particles (b). A person skilled in toe art will understand that any range formed by any of toe explicitly disclosed lower limits and upper limits is explicitly encompassed in the present specification.

Suitable additional monomers for the preparation of the oxirane-functional latex polymer (b) according to the present invention can be selected from

ethytenicaiiy unsaturated nitrile compounds;

vinyl aromatic monomers;

alkyl esters of ethylemcally unsaturated adds;

hydroxyalkyi esters of ethytenicaiiy unsaturated adds;

amides of ethytenicaiiy unsaturated acids;

ethyienically unsaturated adds;

ethytenicaiiy unsaturated sulfonic add monomers and/or ethytenicaiiy unsaturated phosphorous-containing add monomers

vinyl carboxyiates;

conjugated dienes;

monomers having at least two ethytenicaiiy unsaturated groups; and

combinations thereof.

Examples of ethytenicaiiy unsaturated nitrile monomers which can be used for toe preparation of the oxirane-functional latex polymer (b) according to toe present invention include polymerizable unsaturated aliphatic nitrile monomers which contain from 2 to 4 carbon atoms in a linear or branched arrangement, which may be substituted either by acetyl or additional nitrile groups. Such nitrite monomers include acrylonitrile,

methacryionitrile, aipha-cya noethyl acrylonitrile, fumaronitrile and combinations thereof, with acrylonitrile being most preferred. Representatives of vinyl-aromatic monomers include, for example, styrene, a- methyistyrene, p-methylstyrene, t-butylstyrene and vinyltoiuene. Preferably, the vinyl- aromatic monomers are selected from styrene, alpha-methyl styrene and combinations thereof.

Esters of{meth)acrylic add that can be used to prepare the oxirane-funtiional latex particles (b) according to the present invention include n-a!kyi esters, iso-aikyt esters or tert-alkyi esters of acrylic or (meth)acrylic acid in which the alkyl group has from 1 to 20 carbon atoms, the reaction product of methacryiic add with glycidyt ester of a neoadd such as versatic add, neodecanoic add or piva!ic add and hydroxyalkyl (meth)acryfate and aikoxyalkyl (meth)acryiate monomers.

In general, the preferred alkyl esters of (meth)acryiic adds may be selected from C ₁ -C ₂₀ alkyl (meth)acrylate, preferably C ₁ -C ₁₀ -alkyf (meth)acryfates. Examples of such acrylate monomers indude n-butyl acrylate, secondary butyl acrylate, methyl acrylate, ethyl acrylate, hexyl acrylate, tert-butyi acrylate, 2-ethyi-hexyi acrylate, isooctyl acrylate, 4- methyl-2-pentyl acrylate, 2-methyibutyl acrylate, methyl methacrylate, butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, ethyl methacrylate, isopropyl methacrylate, hexyl methacrylate, cyelohexyl methacrylate and cetyl methacrylate. It Is particularly preferred to select the esters of (methacryiic adds from methyl (methacrylate, ethyl {methacrylate, propyl (meth)acrytate, butyl (meth)acrylate, 2-ethylhexyl (methacrylate and combinations thereof.

The hydroxy alkyf(meth)acrytaie monomers which can be used to prepare the oxirane- functional latex polymer (b) according to the present invention indude hydroxyalkyl acrylate and methacrylate monomers which are based on ethylene oxide, propylene oxide and higher a!kyiene oxides or mixtures thereof. Examples are hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydraxypropyl methacrylate and hydroxybutyi acrylate. Preferably, the hydroxy alkyl(meth)acrylate monomer is selected from 2-hydroxy ethyl (methacrylate.

Amides of ethylenlcally unsaturated adds that can be used for the preparation of the oxirane-functional latex polymer (b) according to the present invention include

acrylamide, methacrylamide, and diacetone acrylamide. The preferred amide monomer is (meth)acrylamide. Vinyl ester monomers which can be used to prepare toe oxirane-functiona! latex polder (b) according to the present invention include vinyl acetate, vinyl proprionate, vinyl butyrate, vinyl benzoate, viny{-2~ethylhexanoate, vinyl stearate, and the vinyl esters of versatic add. The most preferred vinyl ester is vinyl acetate.

The ethyienicaily unsaturated carboxylic add monomers suitable for the preparation of the oxirane-functiona! latex polymer (b) according to the present invention indude monocarboxylic add and dicarboxylic add monomers and monoesters of dicarboxylic acid. Carrying out the present invention, it is preferable to use ethyienicaily unsaturated aliphatic mono- or dicarboxylic adds or anhydrides which contain from 3 to 5 carbon atoms. Examples of monocarboxylic add monomers include acrylic add, methacrylic add, crotonic acid and examples of dicarboxylic acid monomers indude fumade add, itaconic add, maleic acid and maleic anhydride. Examples of other suitable ethyienicaily unsaturated adds indude vinyl acetic add, vinyl lactic add, vinyl sulfonic add, 2-methyl- 2-propene- 1 -sulfonic add, styrene sulfonic add, acrylamidomethyl propane sulfonic add and the salts thereof. Preferably, the ethyienicaily unsaturated carboxylic add monomers are selected from (meth)acrylic acid, crotonic add, itaconic add, maleic add, fumarre add and combinations thereof. Conjugated diene monomers suitable for toe preparation of the oxirane-functiona! latex polymer (b) according to the present invention include conjugated diene monomers, selected from t ,3-butadiene, isoprene, 2,3-dimethyl-1 , 3-butadiene, 2, 3-dimethyl- 1,3- butadiene, 2-chioro-1 ,3-butadiene, 1 ,3-pen!adiene, 1,3-hexadiene, 2,4-hexadiene , 1,3- odadiene, 2-methyi-1 ,3-pentadiene, 2,3-dimethyl- 1 ,3-pentadiene, 3,4-dimethyl-1,3- hexadiene, 2, 3-diethyl- 1 ,3-butadiene, 4,5-dlethyl-1 ,3-octadiene, 3-butyt-1 ,3-octadlene,

3.7-dimethyi~1 ,3,6-odatiiene, 2-methyl-6-methyfene-1 ,7-octadiene, 7- methyl-3- methylene-1 ,6-octadiene, 1,3,7-octatriene, 2-etoyl-1, 3-butadiene, 2-amyl-1 ,3-butadiene,

3. 7-d«metoyl-1 ,3,7-octatriene, 3,7-d»methyl-1,3,6-octatriane, 3,7,11-trimethyl-1,3,6,10- dodecatetraene, 7, 11-dimethyf-3~methy1ene-1 ,6,10-dodecalriene, 2,6-dimethyl-2,4,6- octatriene, 2-phenyl-1 ,3-butadiene and 2-methyl-3-isopropyi- 1 ,3-butadiene and 1 ,3- cyclohexadiene. 1, 3-Butadiene, isoprene and combinations thereof are the preferred conjugated dienes.

Furthermore, monomers having at least two ethyienicaily unsaturated groups can be used in the preparation of the oxirane-functiona! latex polymer (b). Suitable bifunctiona! monomers which are capable of providing Internal crosslinking and branching in the polymer (herein known as multifunctional monomers), may be selected from divinyl benzene and diacrylates and di( methacrylates. Examples are ethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, tripropyiene glycol di(meth) acrylate, butanediol di(meth)acrylate, neopentyi glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethytene glycol di( meth)acrytate, and dipropylene glycol

di(meth)acrylate. The monomers having at least two ethylenically unsaturated groups are preferably selected from divinyl benzene 1,2-ethyteneglycol di(me8i)acrylate, 1,4- butanediol di(meth)acfylate and 1,6-hexamdlol di(meth)acryiate.

The oxirane-functional latex polymer (b) according to the present invention may comprise structural units derived from

0 to 50 wt-%, preferably 0 to 30 wt-%, more preferred 0 to 20 wt-%, of monomers selected from ethylentcaliy unsaturated nitrile compounds, preferably acrylonitrile;

0 to 95 wt-%, preferably 0 to 70 wt-%, more preferred 0 to 50 wt-% of vinyl aromatic monomers, preferably styrene;

0 to 95 wt-%, preferably 5 to 95 wt-%, more preferred 20 to 95 wt-% of C ₁ to C ₆ alkyl (methacrylates;

0 to 10 wt-%, preferably 0 to 7 wt-%, more preferred 0.01 to 7 wt-% of ethytenica!iy unsaturated acids, preferably (meth)acryiic add;

0 to 10 wt-%, preferably 0 to 8 wt-%, more preferred 0 to 6 wt-% of ethylenically unsaturated compounds bearing silane, sulfonate, sulfonic add, phosphate, amide and/or N-methy!oiamide groups;

0 to 50 wt-%, preferably 0 to 40 wt-%, more preferred O to 20 wt-% of vinyl carboxyiates, preferably vinyl acetate;

1 to 80 wt-%, preferably 20 to 70 wt-%, more preferred 25 to 65 wt-%, most preferred 35 to 65 wt-% of structural units derived from ethylenically unsaturated oxirane-functional monomers.

Alternatively, the oxirane-functional latex polymer (b) according to the present invention may comprise structural units derived from

2 to 95 wt.-%, preferably 10 to 95 wt-%, more preferred 20 to 95 wt-% of conjugated dienes, preferably selected from butadiene, isoprene and

combinations thereof, more preferred butadiene;

1 to 50 wt.-%, preferably 5 to 50 more preferred 5 to 40 wt-% of monomers selected from ethylenically unsaturated nitrile compounds, preferably acrylonitrile; 0 to 95 wt-%, preferably 0 to 90 wt-%, more preferred 0 to 70 wt-%, of vinyl aromatic monomers, preferably styrene; 0 to 95 wt-%, preferably 0 to 90 wt-%, more preferred 0 to 70 wt.-% of C ₁ to C ₈ alkyl (methacrylates;

0 to 10 wt.-%, preferably 0 to 8 more preferred 0 to 7 wt-% of eihyfenicaily unsaturated adds, preferably (meth)acrylic add;

0 to 10 wt.-%, preferably 0 to 8 wt.-%, more preferred 0 to 6 wt.-% of ethyfenicaUy unsaturated compounds bearing silane, sulfonate, sulfonic acid, phosphate, amide and/or N~meihyiolamide groups,

1 to 80 wt.-%, preferably 20 to 70 wt.-%, more preferred 25 to 65 wt.~%, most preferred 35 to 65 wt-% of structural units derived from ethytenically unsaturated oxrrane-functional monomers.

According to the present invention, the amounts of the above-defined monomers for the preparation of latex polymer (b) may add up to 100 wt-% The glass transition temperature (mid-point temperature Tmg) of the oxirane-functional latex polymer (b) according to the present invention may be -50 ^* to 50°C as measured by DSC according to ASTM D3418-03, preferably -40 °C to 40 °C, more preferably -30°G to 30°C, more preferred -25°C to 25°C and most preferred -22X to 22°C. Thus, the lower limit of the Tmg range may be -50, -45, -40, -38, -36, -34, -32. -30, -29, -28. -27, - 26, - 25, -24, -23, or -22 °C. The upper limit of the Tmg range may be 50, 45, 40, 38, 36, 34, 32, 30, 29, 28, 27, 26, 25, 24, 23, or 22°C. A person skilled in the art will understand that any range formed by any of the explicitly disclosed lower limits and upper limits is explicitly encompassed in the present specification. The z-average particle size measured with a Malvern zetasizer nano S (ZEN 1600) using dynamic light scattering (DLS) of toe oxirane-functional latex particles (b) according to the present invention, irrespective of whether it is employed as latex, added during the polymerization of latex polymer (a) or as preformed latex blended with the latex polymer (a), is preferably 5 to 90 nm, more preferably 15 to 85 nm, more preferred 20 to 80 nm. The lower limit of the z-average particle size therefore can be 5 nm, 7nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm. 16 nm, 17 run, 18 nm, 19 nm, or 20 nm, whereas the upper Hmit can be 90 nm, 85 nm, 80 nm, 75 nm, 70 nm, 85 nm, 60 nm, 55 nm, 50 run, 45 nm, 40 nm, 38 run, 36 nm, 34 nm, 32 nm, or 30 nm. A person skilled in the art will understand that any range formed by any of the explicitly disclosed lower limits and upper limits is explicitly encompassed in the present specification. A person skilled in the art will appreciate that the oxirane-functional latex polymer (b) of the present invention can be used as particles (for example as seed particles) present in the emulsion polymerization of the latex polymer (a) or can be blended with a preformed latex polymer (a) whereby the preformed latex polymer (a) can be made by emulsion polymerization with or without oxirane-functional latex polymer (b) according to the present invention as particles present in the emulsion polymerization for example as seed particles. The person skilled in the art will also appreciate that the oxirane-functional latex particles (b) used as particles present in the emulsion polymerization of the preformed latex polymer (a) and the oxirane-functional latex polymer (b) blended with the preformed latex polymer (a) may be the same or different.

Latex polymer fat

According to the present invention the mixture of ethyienically unsaturated monomers for preparing the latex polymer (a) comprises

15 to 99 wt.-% of conjugated dienes;

1 to 80 wt-% of monomers selected from ethyienicaily unsaturated nitrite compounds;

0.05 to 10 wt.-% of ethytenicalfy unsaturated carboxylic adds and/or salts thereof; 0 to 50 wt-% of vinyl aromatic monomers; and

0 to 65 wt -% of alkyl esters of ethyienically unsaturated acids,

the weight percentages being based on the total monomers employed in the emulsion polymerization. In the mixture of ethyienically unsaturated monomers additional ethyienically unsaturated monomers may be present, that are selected from

hydroxyalkyl esters of ethyfenically unsaturated acids;

amides of ethyienically unsaturated acids;

vinyl carboxyiates;

monomers having at least two ethyienically unsaturated groups;

ethyienically unsaturated silanes;

oxirane functional ethyienically unsaturated compounds; and

combinations thereof. According to the present invention the mixture of ethyienically unsaturated monomers for preparing the latex polymer (a) may be free of oxirane functional monomers. Conjugated diene monomers suitable for the preparation of latex polymer (a) according to the present invention include conjugated diene monomers, selected from 1 ,3-butadiene, isoprene, 2,3-dimethyl-1 ,3-butadiene, 2, 3-dimethyl-1, 3-butadiene, 2~chloro-1, 3-butadiene,

1.3- pentadiene, 1 ,3-hexadiene, 2,4-hexadiene, 1,3-octadiene, 2-mefoyl-1,3-pentadiene, 2, 3-dimethyl- 1 ,3-pentadiene, 3,4- dimethyi-1 ,3-hexadiene, 2,3-diethyl-1 ,3-butadiene, 4,5- diethyi-1 ,3-octadiene, 3-butyl- 1 ,3-octadiene, 3,7-dimethyl-1 ,3,6-octatriene, 2-methyf-6- methylene-1 ,7-octadiene, 7-methyl-3-methyiene-1 ,6-octadiene, 1,3,7-octatriene, 2-ethyl-

1.3-butadiene, 2-amyi-1 , 3-butadiene, 3,7-dimethyl-1, 3, 7- octatriene, 3,7-dimethyf- 1 ,3,6- octatriene, 3,7,11- trimethyl-1 ,3,6,10-dodecatetraene , 7,11-dimethyl-3-methyiene-1 ,6,10- dodecatriene, 2,6-dimethyi-2,4,6-octatriene, 2-phenyl-1 ,3-butadiene and 2-methyt-3- isopropyi- 1 ,3-butadiene, 1 ,3-cydohexadiene, myrcene, ocimene, and famasene. 1,3- Butadiene, isoprene and combinations thereof are the preferred conjugated dienes. 1,3- Butadiene is the most preferred diene. Typically, the amount of conjugated diene monomer ranges from 15 to 99 wt.-%, preferably from 20 to 99 wt.-%, more preferred from 30 to 75 most preferred from 40 to 70 wt-%, based on the total weight of monomers. Thus, the conjugated diene may be present in amounts of at least 15 wt at least 20 wt.-%, at least 22 wb-%, at least 24 wt.-%, at least 26 wt.~%, at least 28 wt-%, at least 30 wt.-%, at least 32 wt-%, at least 34 wt.-%, at least 36 wt.-%, at least 38 wt.-%, or at least 40 wt-%, based on the total weight of the ethyienically unsaturated monomers for latex polymer (a).

Accordingly, the conjugated diene monomers can be used in amounts of no more than 95 wt-%, no more than 90 wt-%, no more than 85 wt-%, no more than 80 wt-%, no more than 78 wt-%, no more than 76 wt-%. no more than 74 wt-%, no more than 72 wt-%, no more than 70 wt-%, no more than 68 wt-%, no more than 66 wt-%, no more than 64 wt- %, no more than 62 wt-%, no more than 60 wt.-%, no more than 58 wt-%, or no more than 56 wt-%. A person skilled in the art will appreciate that any range between any of the explicitly disclosed lower and upper limit is herein disclosed.

Unsaturated nitrile monomers which can be used to make the particles of latex polymer (a) include polymerizable unsaturated aliphatic nitrile monomers which contain from 2 to 4 carbon atoms in a linear or branched arrangement, which may be substituted either by acetyl or additional nitrile groups. Such nitriie monomers include acrylonitrile,

methacrytonitrile, alpha-cyanoethyl acrylonitrile, fumaronitrile and combinations thereof, with acrylonitrile being most preferred. These nitrile monomers can be included in amounts from 1 to 80 wt.-%, preferably from 10 to 70 wt-%, or 1 to 60 wt-%, and more preferred from 15 to 50 wt-%, even more preferred from 20 to 50 wt-%, most preferred from 23 to 43 wt.-%, based on the total weight of ethyleracally unsaturated monomers for latex polymer (a).

Thus, the unsaturated nitrile may be present in amounts of at least 1 wt-%,

5 wt-%, at least 10 wt.-%, at least 12 wt-%, at least 14 wt-%, at least 16 wt-%, at least 18 wt-%, at least 20 wt-%, at least 22 wt-%, at least 24 wt-%, at least 26 wt-%, at least 28 wt-%, at least 30 wt-%, at least 32 wt-%, at least 34 wt-%, at least 36 wt-%, at least 38 wt-%. or at least 40 wt-%, based on the total weight of the ethytenicaliy unsaturated monomers for latex polymer (a).

Accordingly, the unsaturated nitrile monomers can be used in amounts of no more than 80 wt.-%, no more than 75 wt.-%, no more than 73 wt.~%, no more than 70 wt.-%, no more than 68 wt.-%, no more than 66 wt.~%, no more than 64 wt-%, no more than 62 wt.~ %, no more than 60 wt.-%, no more than 58 wt-%, no more than 56 wl-%, no more than 54 wt-%, no more than 52 wt.-%, no more than 50wt.-%, no more than 48 wt-%, no more than 46 wt.-%, or no more than 44wt.-%. A person skilled in the art will appreciate that any range between any of the explidily disclosed lower and upper limit is herein disdosed. The ethytenicaliy unsaturated carboxylic acids or salts thereof may be selected from monocarboxyiic acid and dicarboxylic acid monomers and their anhydrides and partial esters of polycarboxylic adds. Carrying out the present invention, it is preferable to use ethylenicafly unsaturated aliphatic mono- or dicarboxylic acids or anhydrides which contain from 3 to 5 carbon atoms. Examples of monocarboxyiic acid monomers indude acrylic add, methacryiic add, crotonic acid and examples of dicarboxylic add monomers indude fumaric add, itaconic acid, maleic add, ds-cydohexene-1 ,2-dicarboxylic add, dimethyimaleic acid, bromomaleic add, 2,3-dichtoromaleic add and (2-dodecen-1-yt) sucdnic add. Examples of polycarboxylic acid partial esters include monomethyl maleate, monomethyl fumarate, monoethyl maleate, monoethyl fumarate, monopropyl maleate, monopropyl fumarate, monobutyl maleate, monobutyl fumarate, mono(2-ethyl hexyl) maleate, mono(2~ethy! hexyl) fumarate. Examples of other suitable ethyienicaliy unsaturated adds indude vinyl acetic add, vinyl lactic add, vinyl sulfonic add, 2-methyl- 2-propene- 1 -sulfonic add, styrene sulfonic add, acryiamidomethyl propane sulfonic acid and the salts thereof. (Math)acrylic acid, crotonic add, itaconic add, maleic add, fumaric acid and combinations thereof are particularly preferred. The use of ethy!enically unsaturated carboxylic acid monomers influences the properties of the polymer dispersion and of the film produced thereof. The type and the amount of these monomers are determined thereby. Typically, such an amount is from 0.05 to 10 wt.~%, particularly from 0.1 to 10 wt.-% or 0.05 to 7 wt.-%, preferably from 0.1 to 9 wt-%, more preferred from 0.1 to 8 wt-%, even more preferred from 1 to 7 wt-%, most preferred 2 to 7 wt.-%, based on the total weight of the ethyienically unsaturated monomers for latex polymer (a). Thus, the ethyienically unsaturated carboxylic add monomers may be present in amounts of at least 0.01 wt.-%, at least 0.05 wt-%, at least 0.1 wt-%, at least 0.3 wt-%, at least 0.5 wt-%, at least 0.7 wt-%, at least 0.9 wt-%, at least 1 wt-%, at least 1.2 wt-%, at least 1.4 wt-%, at least 1.6 wt-%, at least 1.8 wt-%, at least 2 wt-%, at least 2.5 wt-%, or at least 3 wt-%. Likewise, the ethyienically unsaturated carboxylic acid monomers may be present in amounts of no more than 10 wt-%, no more than 9.5 wt-%, no more than 9 wt-%, no more than 8.5 wt-%, no more than 8 wt-%, no more than 7.5 wt-%, no more than 7 wt-%, no more than 6.5 wt-%, no more than 6 wt-%, no more than 5.5 wt-%, or no more than 5 wt-%, based on the total weight of ethyienically unsaturated monomers for latex polymer (a). A person skilled in the art will appreciate that any range defined by an explicitly distiosed lower limit and an explicitly disclosed upper limit is disclosed herewith. Representatives of vinyl-aromatic monomers indude, for example, styrene, a- methylstyrene, vlnyltoluene, o-methyistyrene, p- methylstyrene, p-tert-butyistyrene, 2,4- dimethylstyrene, 2-methyistyrene , 3-methylstyrene, 4-methylstyrene, 2-ethyistyrene, 3- ethylstyrene, 4-ethyls tyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-buty1~2-methylstyrene, 2- chlorostyrene, 3-chlorostyrene, 4 -ch!orostyrene, 4~ bromostyrene, 2-methyi-4,6-dichiorastyrene , 2, 4-dibromostyrene, vinylnaphthalene, vinyltoluene and vinytxylene. 2-vinylpyridine, 4-vinylpyridine and 1,1- dipheny!ethyienes and substituted 1 , 1 -diphenyiethyienes , 1 , 2-diphenylethene and substituted 1,2- di phe nylethytenes. Mixtures of one or more of the vinyl -aromatic compounds may also be used. The preferred monomers are styrene and «-methylstyrene. The vinyl-aromatic compounds can be used in a range of from O to 50 wt-%, preferably from 0 to 40 wt.-% more preferred from 0 to 25 wt-%, even more preferred from 0 to 15 wt.-%, and most preferred from 0 to 10 wt-%, based on the total weight of ethyienically unsaturated monomers for latex polymer (a). Thus, the vinyl-aromatic compound can be present in an amount of no more than 35 wt.-%. no more than 30 wt.-%, no more than 25wt.-%, no more than 20 wt-%, no more thanlS wt-%, no more than 16 wt-%, no more than 14 wt- %, no more than 12 wt.-%, no more than 10 wt-%, no more than 8 wt-%, no more than 6 wl-%, no more than 4 wt-%, no more than 2 wt.-%, or no more than 1 wt.-%, based cm the total weight of ethytenicaily unsaturated monomers for iatex potymer (a). Vinyl- aromatic compounds may also be completely absent Further, the mixture of ethytenicaily unsaturated monomers for Iatex polymer (a) according to the present invention may indude additional ethytenicaily unsaturated monomers that are different from the above-defined monomers. These monomers may be selected from esters of (meth)acrytic add, vinyl esters, and amides of ethytenicaily unsaturated acids or ethytenicaily unsaturated silane compounds.

Vinyl ester monomers which can be used according to the present invention indude vinyl acetate, vinyl proprionate, vinyl butyrate, vinyl benzoate, vinyl-2-ethylhexanoate, vinyl stearate, and the vinyl esters of versatic add. The most preferred vinyl ester monomer for use in the present invention is vinyl acetate. Typically, the vinyl ester monomers can be present in an amount of no more than 18 wt.-%, no more than 16 wt-%, no more than 14 wt-%, no more than 12 wt-%, no more than 10wt.~%, no more than 8 wt-%, no more than 6 wt-%, no more than 4 wt-%, no more than 2 wt-%, or no more than 1 wt-%, based on the total weight of ethytenicaily unsaturated monomers for latex polymer (a). Examples of suitable ethylenical!y unsaturated silane compounds can be selected from triethoxyvi nyisilane and 3-methacryioxypropyltrimethoxysiiane. The ethytenicaily unsaturated silane compounds can be present in an amount of 0.05 to 5.0 wt-%, preferably 0.3 to 2.0 wt-%, more preferred 0.3 to 1.0 wt-%, based on the total weight of ethytenicaily unsaturated monomers for latex polymer (a).

Esters of (meth)acryfic acid that can be used according to the present invention include n- aikyt esters, iso-alkyl esters or tert-akyi esters of acrylic or (meth)acryiic add in which the alkyl group has from 1 to 20 carbon atoms, the reaction product of methacrylic add with gtyddyl ester of a neoadd such as versatic add, neodecanoic add or pivalic add and hydroxyalkyl (meth)acrytate and a!koxya!kyt (methjacryiate monomers.

In general, the preferred alkyl esters of (meth)acrylic acids may be selected from C ₁ -Cto alkyl (methacrylate, preferably C ₁ -Ce-alkyl (methacrylates. Examples of such acrylate monomers include n-buty! acrylate, secondary butyl acrylate, ethyl acrylate, hexyl acrylate, tert-butyl acrylate, 2-ethyt-hexyi acrylate, isooctyl acrylate, 4~methyi-2-pentyi acrylate, 2-methyibutyt acrylate, methyl methacrylate, butyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, etiiyi methacrylate, isopropyl methacrylate, hexyl methacryiate, cyclohexyi methacrylate and cetyl methacrylate. Methyl (meth)acryiate, ethyl (methacrylate, propyl (meth)acrytate, butyl (meth)acrylate, 2-ethy!hexyl

(meth)acryiate and combinations thereof are preferred. Typically, the alkyl (methacryiate monomers can be present in an amount of no more than 18 wt-%, no more than 16 wt.-%, no more than 14 wt-%, no more than 12 wt-%, no more than 10 wt.-%, no more than 8 wt-%, no more than 6 wt-%, no more than 4 wt.-%, no more than 2 wt-%, or no more than 1 wt-%, based on the total weight of ethylenically unsaturated monomers for latex polymer (a).

The hydroxy alkyl{meth)acrylate monomers which can be used to prepare the polymer latex according to the present invention include hydroxyaikyi acrylate and methacrylate monomers which are based on ethylene oxide, propylene oxide and higher a!ky!ene oxides or mixtures thereof. Examples are hydroxyefoyf acrylate, hydroxypropyi acrylate, hydroxyefoyf methacrylate, hydroxypropyi methacryiate and hydroxybutyl acrylate.

Preferably, the hydroxy alkyi(mefo}acry!ate monomer is 2-hydroxy ethytf meth)acryiate. Typically, hydroxy alkyl (meth)acrylate monomers can be present in an amount of no more than 18 wt-%, no more than 16 wt-%, no more than 14 wt.-%, no more than 12 wt.- %, no more than 10 wt-%, no more than 8 wt-%, no more than 6 wt-%, no more than 4 wt-%, no more than 2 wt-%, or no more than 1 wt-%, based on the total weight of ethylenically unsaturated monomers for latex polymer (a).

Alkoxyalkyl (meth)acryiate monomers which can be used in the present invention include methoxyethyl methacrylate, ethoxyethyl methacrylate, methoxyethyl methacrylate, ethoxyethyl acrylate, butoxyethyi methacryiate, methoxybutyl acrylate and

methoxyethoxyethyl acrylate. Preferred alkoxyalkyl meth)acryfate monomers are ethoxyethyl acrylate and methoxyethyl acrylate. Typically, the amount of alkoxyethyl alkyl (meth)acrylate monomers can be present in an amount of no more than 18 wt.-%, no more than 16 wt.-%, no more than 14 wt.-%, no more than 12 wt-%, no more than 10 wt- %, no more than 8 wt-%, no more than 6 wt -%, no more than 4 wt-%, no more than 2 wt -%, or no more than 1 wt.-%, based on the total weight of ethylenically unsaturated monomers for latex polymer (a).

Amides of ethyientca!ly unsaturated acids that can be used for the preparation of the polymer latex according to the present invention include acrylamide, methacrylamide, and diacetone acrylamide. The preferred amide monomer is (methacrylamide. In order to introduce functional groups that are capable of seff-crossiinking upon heat treatment into the polymer particles of the present invention monomers comprising N-methyk>i amide groups may be employed. Suitable monomers are N-methytoi (meth)acryiamide, N- methoxymethyl-(meth)acrylamide, N-n~butoxy-methyl-(meth)acryiamide, N-iso-butoxy- methyl-(meth)acrylam ide, N-acetoxymethyKmeth)acrylam«de, N(-2, 2-dimethoxy- 1 - hydroxyethyi) acrylamide. Typically, amides of ethylenically unsaturated add can be present in an amount of no more than 18 wt-%, no more than 16 wt.-%, no more than 14 wt.-%, no more than 12 wt.-%, no more than 10 wt.-%, no more than 8 wt.-%, no more than 6 wt-%, no more than 4 wt-%, no more than 2 or no more than 1 wt-%, based on the total weight of ethylenically unsaturated monomers for latex polymer (a).

Furthermore, monomers having at least two ethylenically unsaturated groups can be present in the monomer mixture for the preparation of the polymer latex of the present invention In an amount 0 to 6.0 wt-%, preferably 0.1 to 3.5 wt-%, based on the total weight of ethyienicai!y unsaturated monomers. Typically, these monomers can be present in an amount of no more than 6 wt-%, no more than 4 wt-%, no more than 2 wt-%, no more than 1 wt-%, based on the total weight of ethylenically unsaturated monomers. Suitable bifuncticnai monomers which are capable of providing internal crossftnking and branching in the polymer (herein known as multifunctional monomers) may be selected from divinyl benzene and diacrylates and di(meth)acryiates. Examples are ethylene glycol di(meth)acrylate, hexanediol di(meth)acryfate, tri propylene glycol di(meth)acrylate, butanediol dKmelhjaaryiate, neopentyl glycol di(meth)acryiate, diethylene glycol di(meth)acryfate, triethylene glycol di(meth)acrylate, and dipropylene glycol

d$(meth)acry!ate. The monomers having at least two ethylenically unsaturated groups are preferably selected from divinyl benzene, 1 ,2 ethyleneglycol di(meth)acrylate, 1 ,4- butanediol di(meth)acrylate, 1 ,6-hexanedlol di(meth)acryiate and trimethylo!propane tri(meth)acry1ate.

Suitable oxirane functional monomers to be used in the preparation of latex polymer (a) are those as described above for toe oxirane functional latex polymer (b) including the preferred embodiments. If employed, the oxirane functional monomers are preferably present in an amount of 5 wt-% at most, more preferred 3 wt.-% at most based on the total amount of monomers to be used in the preparation of latex polymer (a). But as mentioned above it is most preferred that latex polymer (a) is free of oxirane functional

The mixture of the ethylenically unsaturated monomers for latex polymer (a) may comprise from; 20 to 99 wt-% of conjugated dienes, preferably selected from butadiene, isoprene and combinations thereof, more preferred butadiene;

1 to 60 wt.-% of monomers selected from ethylenicaliy unsaturated nitrile compounds, preferably acrylonitrile;

0 to 40 wt-% of vinyl aromatic monomers, preferably styrene;

0 to 25 wt-% of C ₁ to Ce alkyl (methjacryiates;

0.05 to 7 wt-% of ethylenicaliy unsaturated adds, preferably (meth)acryiic acid;

0 to 10 wt.-% of vinyl esters:

O to 10 wt.-% of ethylenicaliy unsaturated compounds bearing silane, amide and/or N-methylolamide groups,

the weight percentages being based on the total monomers present in toe mixture.

According to toe present invention, the amounts of the above-defined monomers for the preparation of latex polymer (a) may add up to 100 wt-%

According to the present invention, toe mixture of ethyienicaiiy unsaturated monomers to be polymerized in toe free-radical emulsion polymerization may also comprise:

(a) 15 to 90 wt-% of isoprene;

(b) 1 to 80 wt-% of acrylonitrile;

(c) 0.01 to 10 wt-%, preferably 0.05 to 10 wb-% of at least one ethylenicaliy

unsaturated acid;

(d) 0 to 40 wt.-% of at least one aromatic vinyl compound, and

(e) 0 to 20 wt.-% of at toast one further ethyienicaiiy unsaturated compound different from any of compounds (a) to (d), The ranges for component (a) and/or (b) may be selected from the ranges for (a) conjugated dienes and (b) unsaturated nitrile as disclosed above. Likewise, specific embodiments and amounts for the components (c),

(d) and/or (e) may be selected from those as described above for components (c), (d) and the additional polymers.

The z-average particle size measured with a Malvern zetasizer nano S (ZEN 1600) using dynamic light scattering (DLS) of the latex particles (a) according to the present invention is preferably 70 to 1000 nm, more preferably 80 to 1000 nm, more preferably 90 to 1000 nm, 100 to 1000 nm, more preferably 110 to 600 nm, more preferred 120 to 500 nm. The lower limit of toe z-average particle size of the latex particles (a) therefore can be 70 nm, 80nm, 90 nm, 100 nm, 105 nm or 110 nm, or 120 nm, the upper limit for the z-average average particle size can be 900 nm, 800 nm, 700 nm, 600 nm, 500 nm, 400 nm, 350 nm, 300 nm, 270 nm, 250 nm, 230 nm, 210 nm or 200 nm. A person skilled in the art will understand that any range formed by any of the explicitly disclosed tower limits and upper limits is explicitly encompassed in the present specification.

According to the present invention it is particularly preferred that the z-average particle size of the latex polymer (a) is larger than the z-average particle size of the latex polymer

(b).

Method for the preparation of the ooivmer latex of the present invention: The latex polymer (a) according to the present invention can be made by any emulsion polymerization process known to a person skilled in the art, provided that the monomer mixture as herein defined is employed. Particularly suitable is the process as described in EP-A 792891. In the emulsion polymerization for preparing the latex polymer (a) of the present invention a seed Iatex may be employed. Preferably, the seed Iatex is the iatex polymer (b) as described above including all disclosed variations. Alternatively, any other seed particles as known to the person skilled in the art can be used. But if no Iatex polymer (b) is used as seed particles, the particles of latex polymer (b) wii! have to be incorporated in the polymer Iatex of the present invention in any other suitable way like mixing a preformed iatex comprising particles of latex polymer (a) with a preformed Iatex comprising particles of Iatex polymer (b).

The seed latex particles are preferably present in an amount of 0.01 to 10, preferably 1 to 5 parts by weight, based on 100 parts by weight of to!ai ethyienical!y unsaturated monomers employed in the polymer latex including those for making the seed particles, such as the oxirane-functional latex particles (b). The lower limit of the amount of seed latex particles therefore can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0,8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5 parts by weight. The upper limit of the amount can be 10, 9, 8, 7, 6, 5.5, 5, 4.5, 4, 3.8, 3.6, 3.4, 3.3, 3.2, 3.1 or 3 parts by weight. A person skilled in the art will understand that any range formed by any of the explicitly disclosed lower limits and upper limits is explicitly encompassed in the present specification.

The process for the preparation of the a bove-described polymer latex can be performed at temperatures of from 0 to 130” C, preferably of from 0 to 100” C, particularly preferably of from 5 to 70” C, very particularly preferably of from 5 to 60” C, in the presence of no or one or more emulsifiers, no or one or more colloids and one or more initiators. The temperature includes all values and sub-values therebetween, especially including 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70. 75, 80. 85, 90. 95, 100, 105. 110, 115, 120 and 125 ^* C.

Initiators which can be used when carrying out the present invention include water- soluble and/or oil-soluble initiators which are effective for the purposes of the

polymerization. Representative initiators are well known in the technical area and include, for example: azo compounds (such as, for example, AIBN, AMBN and cyanovaieric acid) and inorganic peroxy compounds, such as hydrogen peroxide, sodium, potassium and ammonium peroxydisulfate, peroxycarbonales and peroxyborates, as well as organic peroxy compounds, such as alkyl hydroperoxides, dialkyi peroxides, acyl hydroperoxides, and diacyf peroxides, as well as esters, such as tertiary butyl perbenzoate and

combinations of inorganic and organic initiators.

The initiator is used in a sufficient amount to initiate the polymerization reaction at a desired rate. In general, an amount of initiator of from 0.01 to 5, preferably of from 0.1 to 4 %. by weight, based on the weight of the total polymer, is sufficient. The amount of initiator is most preferably of from 0.01 to 2% by weight, based on the total weight of the polymer. The amount of initiator indudes all values and sub-values therebetween, especially induding 0.01 , 0.1 , 0.5, 1 , 1.5, 2, 2.5, 3, 4 and 4.5 % by weight, based on the total weight of the polymer.

The above-mentioned inorganic and organic peroxy compounds may also be used alone or in combination with one or more suitable reducing agents, as is well known in the art Examples of such redudng agents which may be mentioned are sulfur dioxide, alkali metal disuifites, alkali metal and ammonium hydrogen sulfites, thiosulfates, dithionites and formaldehyde su!foxyiates, as well as hydroxylamine hydrochloride, hydrazine sulfate, iron (II) sulfate, cuprous naphfoanate, glucose, sulfonic add compounds such as sodium methane sulfonate, amine compounds such as dimefoyianiiine and ascorbic acid. More preferred is the use of a proprietary sodium salt of an organic suifinic acid derivative, such as Bruggolite® FF6 or Bruggolite® FF6M. The quantity of the reducing agent is preferably 0.03 to 10 parts by weight per part by weight of the polymerization initiator.

Surfactants or emulsifiers which are suitable for stabilizing the latex partides include those conventional surface-active agents for polymerization processes. The surfactant or surfactants can be added to the aqueous phase and/or the monomer phase. An effective amount of surfactant in a seed process is the amount which was chosen for supporting the stabilization of the particle as a colloid, the minimization of contact between tire particles and the prevention of coagulation. In a non-seeded process, an effective amount of surfactant is the amount which was chosen for influencing the particle size.

Representative surfactants indude saturated and ethyienicai!y unsaturated sulfonic adds or salts thereof, including, for example, unsaturated hydroca rbonsutfonic add, such as vinylsuifonic add, aHytsutfomc add and methally!sulfonie add, and salts thereof; aromatic hydrocarbon adds, such as, for example, p-styrenesulfonic add,

isopropenylbenzenesulfonic add and vinyioxybenzenesulfonic add and salts thereof ; sulfoalkyl esters of acrylic add and methacrylic add, such as, for example, sulfoethyi methacrylate and sulfopropyl methacrylate and salts thereof, and 2-acrylamido-2- methyl propa nesulfonic add and salts thereof; alkylated diphenyl oxide disulfonates, sodium dodecylbenzenesulfonates and dihexyl esters of sodium sulfosucdnate, Sodium alkyl esters of sulfonic add, ethoxyiated aikyiphenois and ethoxylated alcohols; fatty alcohol (poJy}ethersulfates.

The type and the amount of the surfactant is governed typically by the number of particles, their size and their composition. Typically, the surfactant is used in amounts of from 0 to 20, preferably from 0 to 10, more preferably from 0 to 5, wt.-%, based on the total weight of the monomers. The amount of surfactant indudes all values and subvalues there between, especially including 0, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19 wt-%, based on the total weight of the monomer. According to one embodiment of the present invention, the polymerization is conducted without using surfactants.

Various protective colloids can also be used instead of or in addition to the surfactants described above. Suitable colloids include polyhydroxy compounds, such as partially acetylated polyvinyl alcohol, casein, hydroxyethyf starch, carboxymethylcel!ulose, hydroxyethylcel!ulose, hydroxypropylcellulose, polysaccharides, and degraded polysaccharides* polyethylene glycol and gum arabic. The preferred protective colloids are carboxymethylcellulose, hyd roxyethylcellulose and hydroxypropylcellulose. In general, these protective colloids are used in contents of from 0 to 10, preferably from 0 to 5, more preferably from 0 to 2 parts by weight, based on the total weight of the monomers. The amount of protective colloids includes all values and sub-values therebetween, especially including 1, 2, 3, 4, 5, 6, 7, 8 and 9 wt.-%, based on the total weight of the monomers.

The person skilled in the art will appreciate the type and amounts of monomers bearing polar functional groups, surfactants and protective colloids that are to be selected to make the polymer latex according to the present invention suitable for dip-molding applications. Thus, it is preferred that the polymer latex composition of the present invention has a certain maximum electrolyte stability determined as critical coagulation concentration of less than 30 mrnot/l CaC½, preferably less than 25 mmol/I, more preferred less than 20 mmol/1, most preferred less than 10 mmoi/l (determined for a total solids content of the composition of 0.1% at pH 10 and 23°C).

If the electrolyte stability is too high, then it will be difficult to coagulate the polymer latex in a dip-molding process, with the result that either no continuous film of the polymer latex on the immersed mold is formed or the thickness of the resulting product is non-uniform.

It is within the routine of the person skilled in the art to appropriately adjust the electrolyte stability of a polymer latex. The electrolyte stability will depend on certain different factors, for example, amount and selection of monomers to be used for making the polymer latex, especially monomers containing polar-functional groups, as well as the selection and amount of the stabilizing system, for example, the emulsion polymerization process for making the polymer latex. The stabilizing system may contain surface-active agents and/or protective cofloids. A person skilled in the art is able, depending on the selected monomers and their relative amounts for making the polymer latex of the present invention, to adjust the stabilizing system in order to achieve an electrolyte stability according to the present invention.

Since there are so many different influences on the electrolyte stability, the adjustment is best made by dial and error experiments. But this can be easily done without any inappropriate effort using the test method for electrolyte stability, as disclosed above.

It is frequently advisable to perform the emulsion polymerization additionally in the presence of buffer substances and chelating agents. Suitable substances are, for example, alkali metal carbonates and hydrogen carbonates, alkali metal phosphates and pyrophosphates (buffer substances) and the alkali metal salts of

ethy!enediam inetetraacetic add (EDTA) or hydroxyf-2-ethytenediaminetriacetic acid (HEEOTA) as chelating agents. The quantity of buffer substances and chelating agents is usually 0.001-1.0 wt.-%, based on the total quantity of monomers.

Furthermore, it may be advantageous to use chain transfer agents (regulators) in emulsion polymerization. Typical agents are, for example, organic sulfur compounds, such as thioesters, 2-mercaptoethanol , 3-mercaptoproplonic add and C1-C12 alkyl mereaptans, n-dodecylmercaptan and t-dodecyimercaptan being preferred. The quantity of chain transfer agents, if present, is usually 0.05-3.0 wt.-%, preferably 0.2-2.0 wt-%, based on the total weight of the used monomers.

Furthermore, it can be beneficial to introduce partial neutralization to the polymerization process. A person skilled in the art will appreciate that by appropriate selections of this parameter the necessary control can be achieved.

Various other additives and ingredients can be «Ikied in order to prepare the latex composition of the present invention. Such additives include, for example: antifoams, wetting agents, thickeners, plasticizers, fillers, pigments, dispersants, optical brighteners, antioxidants, biocides and metal chelating agents. Known antifoams include silicone oils and acetylene glycols. Customary known wetting agents include aikyiphenoi ethoxyiates, alkali metal dialkylsulfosuccinates, acetylene glycols and alkali metal alkylsulfate. Typical thickeners include polyacrylates, polyacrylamides, xanthan gums, modified celluloses or particulate thickeners, such as silicas and clays. Typical plasticizers include mineral oil, liquid poiybutenes, liquid potyacrylates and lanolin. Titanium dioxide (Ti<½), calcium carbonate and day are the fillers typically used.

In an alternative embodiment of the present invention a polymer latex comprising the particles of latex polymer (a) and a polymer latex comprising the particles of latex polymer (b) are preformed and subsequently both latices are combined. The emulsion

polymerization for the preparation of the preformed latices comprising the latex polymer (a) and the latex polymer (b) respectively can be conducted in the same manner as described above for the preparation of the latex comprising the latex polymer (a) including ail variations disclosed.

The polymer latex of the present invention may comprise 50 to 99 wt-%, preferably 60 to 98, more preferred 65 to 97, most preferred 70 to 96 wt.-%, based on the total weight of latex particles in the composition of particles of latex polymer (a) and 1 to 50 wt-%, preferably 2 to 40, more preferred 3 to 35, most preferred 4 to 30 wt.-%, based on the total weight of latex particles in the composition of the oxirane-functional latex polymer (b). Thus, the lower limit for the amount of particles of latex polymer (a) may be 50 wt-%, or 55 wt.-%, or 58 wt-%, or 60 wt-%, or 62 wt.-%, or 63 wt.-%, or 64 wt.-%, or 65 wt-%, or 66 wt-%, or 67 wt-%, or 68 wt-%, or 69 or 70 wt-%, based on the total weight of latex particles in the composition. The upper limit for the amount of particles of latex polymer (a) may be 99 wt-%, or 98 wt-%, or 97 wt-%, or 96 wt.-%, or 95 wt-%, or 94 wt-%, or 93 wt-%, or 92 wt-%, or 91 wt-%, or 90 wt-%, or 89 wt-%, or 88 wt-%, or 87 wt-%, or 86 wt-%, or 85 wt-%, car 84 wt-%, or 83 wt-%, or 82 wt-%, or 81 wt-%, or 80 wt-%, based cm the total weight of latex particles in the composition. The lower limit for the amount of particles of latex polymer (b) may be 1 wt.-%, or 1 wt-%, or 1 wt-%, or 1 wt-%, or 5 wt-%, or 8 wt-%, or 7 wt-%, or 8 wt-%, or 9 wt-%, or 10 wt-%, or 11 wt-%, or 12 wt-%, or 13 wt-%, or 14 wt-%, or 15 wt-%, or 16 wt-%, or 17 wt-%, or 18 wt-%, or 19 wt-%, or 20 wt-%, based on the total weight of latex particles In the composition. The upper limit for the amount of particles of latex polymer (b) may be 50 wt-%, or 45 wt-%, or 42 wt-%, or 40 wt-%, or 38 wt-%, or 37 wt-%, car 36 wt-%, or 35 wt-%, or 34 wt-%, or 33 wt-%, ex 32 wt-%, or 31 wt-%, or 30 wt-%, based cm the total weight of latex particles in the composition. A person skilled in the art will understand that any range formed by any of the explicitly disclosed lower Smite and upper limits is explicitly encompassed in the present specification.

For the preparation of the polymer latex of the present invention it is also possible that the mixture of efoyleracally unsaturated monomers for latex polymer (a) is polymerized in presence of particles of the oxirane-functional latex polymer (b) in the free-radical emutskm polymerization forming a first polymer latex, (for example particles of the oxirane-functional latex polymer (b) can be present as seed particles) to form a first polymer latex and a second polymer latex comprising the particles of latex polymer (b) is preformed and subsequently both !atices are combined, wherein the the oxirane- functional latex polymer (b) present in the polymerization of latex polymer (a) and the second polymer latex comprising the particles of latex polymer (b) may be the same or different. The respective emulsion polymerizations for forming the first and the second latex can be conducted in the same manner as described above for the preparation of the latex comprising the latex polymer (a) including all variations disclosed.

In said case the polymer latex of the present invention may comprise 50 to 99 wt.-%, preferably 60 to 96, more preferred 65 to 97, most preferred 70 to 96 wt-%, based on the total weight of latex particles in the composition of particles of latex polymer (a) prepared in presence of particles of the oxirane-functional latex polymer (b) in an amount of 0.01 to 10, preferably 1 to 5 parte by weight based on 100 parte by weight of total ethy!enicaNy unsaturated monomers in the polytier latex (a) including those for making the oxirane- funetional latex polymer (b) present in the polymerization of latex polymer (a) and 1 to 50 wt.-%, preferably 2 to 40, more preferred 3 to 35, most preferred 4 to 30 wt-%, based on the total weight of latex particles in the composition of the second oxirane-fu notional latex particles (b).

The tower limit of toe amount of oxirane-functional latex polymer (b) for toe preparation of toe first latex therefore can be 0,01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or2.5 parts by weight. The upper limit of the amount can be 10, 9, 8, 7, 6, 5.5, 5, 4.5, 4, 3.8, 3.6, 3.4, 3.3, 3.2, 3.1 or 3 parts by weight A person skilled in toe art will understand that any range formed by any of toe explidtly disclosed tower limits and upper limits is explicitly encompassed in the present specification.

Thus the tower limit for the amount of particles of the latex polymer (a) may be 50 wt.~%, or 55 wt-%, or 58 wt-%, or 80 wt-%, or 62 wt-%, or 63 wt.-%, or 64 wt.~%, or 65 wt.~%, or 66 wt.-%, or 67 wi-%, or 68 wt-%, or 69 wt.-%. or 70 wt-%. based on the total weight of latex particles in the composition. The upper limit for the amount of particles of the latex polymer (a) may be 99 wt-%, or 98 wt-%, or 97 wt-%, or 96 wt-%, or 95 wt-%, or 94 wt-%, or 93 wt-%, or 92 wt-%. or 91 wt-%, or 90 wt-%, or 89 wt-%, or 88 wt-%, or 87 wt-%, or 86 wt-%. or 85 wt-%. or 84 wt-%, or 83 wt-%, or 82 wt-%, or 81 wt-%, or 80 wt-%, based on the total weight of latex particles in the composition. The lower limit for the amount of particles of the second latex polymer (b) may be 1 wt-%, or 1 wt-%, < x 1 wt-%, or 1 wt-%, or 5 wt-%, or 6 wt-%, or 7 wt-%, or 8 wt-%, or 9 wt-%, or 10 wt~

%, or 11 wt-%, or 12 wt-%, or 13 wt-%, or 14 wt-%, or 15 wt~%, or 16 wt-%, or 17 wt-%, or 18 wt-%, or 19 wt-%, or 20 wt-%, based on the total weight of latex particles In toe composition. The upper limit for toe amount of particles of toe second latex polymer (b) may be 50 wt-%, ex' 45 wt-%, ex' 42 wt-%, or 40 wt-%, or 38 wt-%, or 37 wt-%, or 36 wt-%, or 35 wt-%, or 34 wt-%, or 33 wt-%, or 32 wt-%, or 31 wt-%, or 30 wt-%, based on toe total weight of latex particles in toe composition. A person skilled in toe art will understand that any range formed by any of the explicitly disclosed lower limits and upper limits is explicitly encompassed in the present specification. Compounded latex composition for the production of dip-molded articles:

The polymer latex to be used to make the elastomeric film is particularly suitable for dipmolding processes. Therefore, the polymer latex is compounded to produce a curable polymer latex compound composition that can be directly used In dip-molding processes. To get reproducible good physical film properties, It Is advisable to adjust the pH of the compounded polymer latex composition by pH modifiere to be in the range of pH 7 to 13, preferably 10.5 to 13, more preferred 11 to 12, for dipping to produce thin disposable gloves. For producing unsupported and/or supported reusable gloves, it is advisable to adjust the pH of the compounded polymer latex composition by pH modifiers to be in the range of pH 8 to 10, preferably 8.5 to 9.5. The compounded polymer latex composition contains the polymer latex of the present invention, optionally the pH modifiere, preferably ammonia or alkali hydroxides and optionally usual additives to be used in these compositions selected from antioxidants, pigments, TK¾, fillers and dispersing agents.

Alternatively, instead of compounding the polymer latex of the present invention also a polymer latex comprising the latex polymer (a) as defined above may be compounded in the same way as described above and during or after the compounding step a polymer latex comprising the oxira ne-functional latex polymer (b) as defined above is added to provide the compounded latex composition of the present invention. Also, a polymer latex comprising the oxirane-functional latex polymer (b) as defined above may be

compounded in the same way as described above and during or after the compounding step a polymer latex (a) as defined above is added to provide the compounded latex composition of the present invention. Of course, all variations with respect to (he latex polymer (a), oxirane-functional latex polymer (b) and their relative amounts based on the total amount of latex polymer as described above can be used.

But it is a particular advantage that sulfur vulcanization systems and cross-linkers and optionally ZnO may be totally avoided, while the polymer latex compound to be used according to the present invention is still curable to provide dip-molded articles having the required tensile and self-healing properties to make them repairable and/or recyclable.

Method for making dip-molded articles: In the method for making dip-molded latex articles according to the present invention, first, a clean mold having the desired shape of the final article is immersed in a coagulant bath comprising a solution of a metal salt. The coagulant is usually used as a solution in water, an alcohof or a mixture thereof. As specific examples of the coagulant the metal salts can be metal halides like calcium chloride, magnesium chloride, barium chloride, zinc chloride and aluminum chloride; metal nitrates such as calcium nitrate, barium nitrate and zinc nitrate; metal sulfates like calcium sulfate, magnesium sulfate, and aluminum sulfate; and acetic add salts such as calcium acetate, barium acetate and zinc acetate. Most preferred are ca!dum chloride and calcium nitrate. The coagulant solution might contain additives to improve the wetting behavior of the former.

Thereafter, the mold is removed from toe bath and optionally dried. The such treated mold is then immersed in the compounded latex composition according to the present invention. Thereby, a thin film of latex Is coagulated on the surface of the mold. It is known In toe art that the thickness of toe thus dipped film may be influenced by the concentration of toe compounded latex and/or the length of time that the salt-coated mold is in contact with the compounded latex. Alternatively, it is also possible to obtain the latex film by a plurality of dipping steps, particularly two dipping steps in sequence.

Thereafter, the mold is removed from the latex composition and optionally immersed in a water bath in order to extract, for example, polar components from the composition and to wash the coagulated latex film.

Thereafter, the latex coated mold is optionally dried at temperature below 80°C,

Finally, the latex coated mold is heat-treated at a temperature of 40-180°C in order to obtain the desired mechanical properties for the final film product. Then, toe final latex film is removed from the mold. The duration of the heat treatment will depend on the temperature and is typically between 1 and 60 minutes. The higher the temperature, the shorter is the required treatment time.

The inventors of the present invention surprisingly discovered that the dip-molding process can be run more economically when employing the polymer latex of the present invention. Particularly, it was discovered that the duration between forming the compounded latex composition according to the present invention and performing the dip-molding step (maturation time) can be considerably reduced to 180 min or less, compared to compounds made from standard !atices that need a maturing time of well above 180 min. Additionaily, the inventors found that toe temperature in toe heat treatment step can be considerably reduced to be within a range of 40°C to less than 120‘C without compromising toe mechanical properties of toe final dip-molded product. Conventional !atices require temperature of 120°0 and above to achieve the desired mechanical properties. Thus, when employing the polymer latex of the present invention, the dipmolding process is less time-consuming and less energy-consuming, making it more economical.

According to the present invention, it is therefore preferred that

in toe compounding step (a)

(i) the polymer latex according to the present invention is compounded by adjusting the pH to a range of 10.5 to 13, preferably 11 to 12, without adding ZnO; or

(»} a polymer latex comprising the particles of the latex polymer (a) as defined above is compounded by adjusting the pH to a range of 10.5 to 13, preferably 11 to 12, without adding ZnO and by subsequently adding preformed particles of latex polymer (b) as defined above; or (III) a polymer latex comprising the particles of polymer (b) as defined above is compounded by adjusting pH to a range of 10.5 to 13, preferably 11 to 12, without adding ZnO and by subsequently adding preformed particles of latex polymer (a) as defined above; and

toe thereby obtained compounded latex composition being free of sulfur vulcanization agents and sulfur vulcanization accelerators and ZnO is matured for less than 180 min, preferably 10 min to 150 min, more preferred 20 min to 120 min, most preferred 30 min to 90 min prior to be employed in the immersing step d); and/or

in heat treating step h) the latex-coated mold is heat-treated at a temperature of 40°C to less than 120°C, preferably 60°C to 100°0, more preferred 70°C to 90°C. The final heat-treated polymer latex film has a tensile strength of at least about 7 MPa and an e tonga tion at break of at least about 300 %, preferably a tensile strength of at least about 10 MPa, an elongation at break of at least about 350 %, more preferred a tensile strength of at least about 15 MPa and an elongation at break of at least about 400 % and even more preferred a tensile strength of at least about 20 MPa and an elongation at break of at least about 500 %. These mechanical properties were measured according tolS037-77 (5th Edition 2011-12-150. This process can be used for any latex article that can be produced by a dip-molding process known in the art.

The artide to be used in the repairing or recyding method according to the present invention may be selected from health care devices formed from elastomeric films or including elastomeric films, surgicai gloves, examination gloves, condoms, catheters or all different kinds of industrial and household gloves. for repairing an elastomeric film or article com said elastomeric him

Items formed from an elastomeric film are collected and sorted and optionally sterilized for handling purposes. The items where there is damage, but not to the extent that they cannot be re-used, are separated and the surface where there is damage is optionally further deaned. This deansing may be by washing with hydrogen peroxide or other sterilizing fluid or by passing under a carbon dioxide air stream or UV light to make sure there are no pathogens present In the location of damage, the surfaces of the damaged film that have separated from one another are brought together such that they contact one another, for example if there is a hole the edges of the hole are brought into contact and the surface is heated so that the elastomeric film can soften and the surfaces seal together to repair the damage after which the surface is allowed to cool and reveal a repaired or self-healed surface. The heating may be carried out where pressure is applied to the contacting areas of the damaged surface.

Method for recycling an elastomeric film or artide comprising said elastomeric film

Elastomeric materials such as gloves are collected and if necessary, they are sorted so that the nitrile containing materials are collected together while the other material is discarded or sent to alternative recycling or reprocessing facilities. The collected material is then washed and decontaminated if necessary, much like is done for the repairing/self- healing process. The material is then comminuted into particle sizes of not more than 2mm average diameter, preferably not more than 1mm average diameter and ideally of diameters in the range of 0.15 to 0.75, more preferably 0.2 to 0.3 average diameter of the particle size. The comminution or grinding process may be earned out at less than room temperature or indeed under cryogenic conditions to enable facile processing and to keep the material as particles before processing further. The cool conditions avoid any rejoining of the particles until needed. The material may be stored at room temperature, or under such conditions that avoid rejoining of the particles until required. The material may be ground further before being fed to a blender where the material is blended with other materials for example particles of virgin elastomeric material and customary processing aids and additives if there is no blending step, the material is fed directly to a thermal processing system where the particles/crumb Is hot pressed, 2-roll milled, calendered or extruded under pressure and at heated conditions i.e. more than 40 degrees centigrade to allow fluidity In the material until the glass transition temperature is reached for the material and at this stage the material can also be molded into the required final shape. After this the material is cooled, optionally in molds or as part of an extrusion process to produce an end product that is formed from recycled material

The present invention will be further illustrated with reference to the following examples. Determination of physical parameters: The dispersions were characterized by determination of total solids content (TSC), pH value, gel content, viscosity (Brookfield LVT) and z-average particle size. Furthermore, the final films were tested for tensile properties.

Determination of total solid contents (TSC):

The determination of total solids content is based on a gravimetric method 1 - 2g of the dispersion was weighed into a tared aluminum dish, on an Analytical balance. The dish was stored for 1 hour at 120 °C in a circulating air oven until constant mass was reached. After cooing to room temperature, the final weight was then re-determined. The solids content was calculated as follows:

where initial mass of latex,

mass after drying

Determination of pH value:

The pH value was determined according to DIN ISO 976. After applying a 2-point calibration using buffer solutions, the electrode of a Schott CG 840 pH meter was Immersed in the dispersion at 23°C and the constant value on the display was recorded as the pH value.

Determination of viscosity:

The latex viscosity was determined at 23 ^* C using a Brookfield IVT viscometer.

Approximately 220 ml of the Squid (freed of air bubbles) was filled into a 250 ml beaker and the spindle of the viscometer was immersed up to the mark on the spindle. The viscometer was then switched-on and after approximately 1 minute the value was recorded until it was constant The viscosity range determines the choice of spindle and rotational speed and the factor for the recorded value to calculate the viscosity. The information regarding spindle and revolutions per minute used are shown in parenthesis in Examples 1, 2 & 8.

Determination of the particle size (PS):

The z-average particle size was measured using a Malvern Zetasizer Nano S (ZEN 1600) using dynamic fight scattering. The latex sample was diluted with deionized water to the turbidity level described in the manual and transferred in die test cuvette. The cuvette was gently mixed to make the sample homogenous and the cuvette was placed in the measurement device. The value was recorded as software generated z-average particle size.

Dipped film preparation:

Nitrile latex with, or without compounding materials at the desired pH value was stirred for 3 hours at room temperature, and then coagulant dipped as follows. A ceramic spade was washed with soap and then thoroughly rinsed with deionized water before drying in an air-circulating oven set at 65-70°0 (spade temperature, 55-60°C) until dry. A solution of coagulant was prepared by dissolving calcium nitrate (18 % wt.) and calcium carbonate (2% wt.) in deionized water. The dry spade was then dipped into the salt solution, removed and then dried in an air-circulating oven set at 70-75°C (spade temperature, 60- 65°C) until dry. The salt-coated spade was then dipped into the desired, compounded latex (which has totai solid content of 18 wt% and matured for 24 hours at room temperature after compounding) for a dwell time of S seconds, before removing it and placing the latex-coated spade into an air circulating oven, set at 100°0 for 1 minute, to gel the film. The thus gelled film was then washed in a tank of deionized water set to 5060°0 for 1 minute, before curing In an air-circulating oven set to 120°C for 20 minutes; after which, She thus cured/vulcanized film was cooled, and removed from the spade before aging for 22 hours in an air-circulating oven set to 100°C. Finally, the cured gloves were manually stripped from the spade, a typical dried film thickness was 0.056 - 0.066mm. The gloves prepared from the latexes were tested for their tensile strength properties, and stress relaxation behavior.

Determination of the tensile strength properties on glove samples:

The tensile properties of the vulcanized or recyded gloves were tested in accordance with IS037-77 (5 ^th Edition 2011-12-15), the dumbbell specimens were cut from gloves prepared from each latex compound using a Type IS037-2 cutter (width of narrow portion - 4mm, length of narrow portion ~ 25mm, overall length≃ 75mm, the thicknesses of the dumbbells are stated in the results Tables) and tested on a Hounsfield HK10KS

Tensiometer fitted with B500LC extensometer, at an extension rate of 500mm/min.

Preparation of recycled glove films:

The samples for the tensile test were prepared by re-combining cut-up samples of the dipped film produced from the original compounded latex, the mixture of small pieces was placed between two polished steel plates before hot pressing at 13.8 MPa (2000psi) for the number of minutes stated in each Example (typically 5 minutes), and at the temperature stated in each Example (typically 100, 120, 150 or 180°C, before being cooled to room temperature and then dumbbell shaped samples cut out using the cutter specified in IS037-77 (5* edition, 2011-12-15), Type IS037-2 die cutter).

Determination of stress relaxation properties

The stress relaxation properties of the elastomer films were performed on dumbbell specimens cut from the gloves prepared from each latex compound using a ASTM D412 Type C cutter (width of narrow portion = 6mm, length of narrow portion = 33mm, overall length = 115mm, the thicknesses of the dumbbells are stated in the results Tables). The tests were performed on a DMA Q800 Dynamic Mechanical Analyser supplied by TA Instruments, which was operated in the“stress relaxation mode', that is in the tension mode; in which the sample was strained to a value of 1% and the initial stress value recorded (G ₀ ). Subsequent stress values were then recorded as a function of time that the sample was held at 1 % strain ((G ₁ ). The following abbreviations are used in the Examples:

BA = n-butyl acrylate

MAA = Methacryiic acid

Bd butadiene

ACN = acrylonitrile

GMA glyddyl methacrylate

lDDM tert-Dodecyi Mercaptan

NaJEDTA = tetra sodium salt of ethyienediaminetetraacetic acid

tBHP tertiary butyl hydroperoxide

TSC total solid content

PS = particle size

ZnO = anc oxide

ZDEC = zinc diethyldithbcarbamate

In the following all parts and percentages are based on weight unless otherwise specified.

Examples

Example 1: Preparation of carboxylated nitrile latex

2 parts by weight (based on polymer solids) of an oxirane-free seed latex (average particle size 36nm) and 80 parts by weight of water (based on 100 parts by weight of monomer including the seed latex) were added to a nitrogen-purged autoclave and subsequently heated to 30° C. Then 0.01 parts by weight of Na<EDTA and 0.005 parts by weight of Bruggolite® FF6 dissolved in 2 parts by weight of water were added, followed by 0.08 parts by weight of sodium persulfate dissolved in 2 parts by weight of water.

Then, the monomers (35 parts by weight of acrylonitrile, 58 parts by weight of butadiene, 5 parts by weight of methacryiic add), and were added together with 0.6 parts by weight of ©DM over a period of 4 hours. Over a period of 10 hours 2.2 parts by weight of sodium dodecyi benzene sulfonate, 0.2 parts by weight of tetra sodium pyrophosphate and 22 parts by weight of waterwene added. The co-activator feed of 0.13 parts by weight of Bruggolite® FF6 in 8 parts by weight of water was added over 9 hours. The temperature was maintained at 30" C up to a conversion of 95 %, resulting in a total solids content of 45 %, The polymerization was short-stopped by addition of 0.08 parts by weight of a 5 % aqueous solution of diethylhydroxyiamine. The pH was adjusted using potassium hydroxide (5 % aqueous solution) to pH 7.5 and the residual monomers were removed by vacuum distillation at 60° C. 0.5 parts by weight of a Wingstay L type antioxidant (60% dispersion in water) was added to the raw latex, and the pH was adjusted to 8.2 by addition of a 5 % aqueous solution of potassium hydroxide.

The following characterization results were obtained for Example 1:

ISC = 44.9 wt. %

pH * 8.2

Viscosity = 38mPas (1/60)

Particle size, P _z = 121 nm

Example 2: Preparation of oxfrane-ftinctional latex

A nitrogen-purged autoclave was charged with 2.0 parts by weight of diphenyl oxide disutfonate dissolved in 185 parts by weight of water relative to 100 parts by weight monomer and heated to a temperature of 70° C. 0.1 parts by weight of tDDM and 0.05 parts by weight of Na4EDTA were added to the initial charge, together with 0.7 parts by weight of ammonium peroxodisulfate (12 % solution in water) added in an aliquot addition. Then 45.4 parts by weight of butadiene, 14.6 parts by weight of acrylonitrile and a solution of 5.0 parts by weight of diphenyl oxide disulfonate dissolved in 50 parts by weight of water were added over a period of 6.5 hours. The addition of 40 parts by weight of GMA was started after 1 hour and added over a period of 6.5 hours. After the addition of the monomers the temperature was maintained at 70° C. The polymerization was maintained up te a conversion of 99 %. The reaction mixture was cooled to room temperature and sieved through a filter screen (90 pm).

The following characterization results were obtained for Example 2:

TSC ~ 37.7 wt %

pH = 7.1

Viscosity x 15mPas ( 1/60)

Particle size, P _z = 39nm

Example 3: (comparative)

A portion of the oxirane-free XNBR latex. Example 1, was adjusted to a pH va!ue of to using an aqueous solution of potassium hydroxide, and compounded with 1 phr zinc oxide. 1 phr titanium dioxide, 0.8 phr of Sulphur and 0.7 phr of ZDEC. The compound was then adjusted to a concentration of 18 % wt. solids and stirred for 3 hours.

Example 4:

To an aliquot of Example 1 (the oxirane-free XNBR latex) was added an aliquot of Example 2 (the oxirane-functional latex), such that the blending ratio was 90:10 by wet weight of Example 1 : Example 2. Preparation of the dip coated samples:

Example 5 (comparative)

A dry, salt-coated spade was then dipped into the compounded latex solution, Example 3, with a dwell time of 5 seconds before the film was gelled at 100°0 for 1 minute, washed with deionised water for 1 minute (in a tank set at 50-60 °C) for 1 minutes, followed by drying and curing/vuicanisation in an air-circulating oven set at 120°C for 20 minutes, to ensure complete drying and crosslink formation. Example 6:

The Mend of Example 4 was adjusted to a pH value of 10 using a solution of potassium hydroxide and toe blend stirred for 3 hours before it was dipped with a dry, salt-coated spade and processed in accordance with toe protocol given in Example 5. Example 7;

The blend of Example 4 was adjusted to a pH value of 10,0 using a solution of potassium hydroxide and compounded with zinc oxide (Iphr), the blend was then stored for 3 hours before it was dipped with a dry, salt-coated spade and processed in accordance with the protocol given in Example 5.

Example 8:

The blend of Example 4 was adjusted to a pH value of 11.5 using a solution of potassium hydroxide and the blend was then stirred for 3 hours before it was dipped with a dry, salt- coated spade and processed in accordance with the protocol given in Example 5.

Stress relaxation experiments

The stress relaxation of a number of samples was tested as a function of time, the samples were prepared according to‘Dipped film preparation” section described above. Example 9:

A dried and cured film obtained from Example 5 (comparative} was then cut in to a number of dumbbell shaped samples (25 ± 0.8mm in length, 6mm in width, and 0.056 - 0.066mm thick) using a pre-shaped cutter (see Fig. 1 ).

The dumbbell was then damped into the jaws of the DMA Q800 Dynamic Mechanical Analyser supplied by TA Instruments, and the sample allowed to equilibrate at the test temperature for 5 minutes before being strained to 1%, and the initial stress value was recorded as Go (see Fig. 2). Maintaining the strain at 1%, toe stress value was then monitored as a function of time at the required test temperature (GO, typically for 1200 seconds (see Fig. 3).

Typical test temperatures chosen were 100, 120, 150 & 180°C.

The stress relaxation was defined as follows,

Stress relaxation = G ₁ / G ₀

The results obtained for Example 9 are shown in Figure 4, the thickness of the test piece is shown in parenthesis on the plot; it should be noted that an line has been drawn at a value of Gi/ Go - 1/e (= 0.63)

Reference: htto://web. mit edu/ccu rse/3/3.11/www/moduies/visco .odf

The time elapsed for the stress to reach a value of 1/e is tabulated below, in Table 1. The stress relaxation values for 120 and 100 °C, did not fall below the 1/e value

Example 10

This was an exact repeat of Example 9, except that Example 6 replaced Example 5; the results are shown in Figure 5, and Table 1.

The result for the stress relaxation experiments is given in Figure 5, and Table 3

This data showed that the data for 100°0 did not fall below the 1/e value; in addition, in contrast to Example 9, the data followed a trend of descending temperature.

Example 11:

This was an exact repeat of Example 9, except that Example 8 replaced Example 5; the results are shown in figure 6, and Table 1.

This data showed that for a zinc oxide-free e!astomeric system compounded to pH 11.5, toe rate of change of the stress relaxation values decreased in toe order of 180 » 150 > 120> 100°0, and all data sets reached the 1/e value.

Table 1

This data is indicative for the re-processability of an elastomeric film made in accordance of the present invention. It is believed that this data can be interpreted that in the inventive examples compared to the comparative examples the cross-links bras* up and the polymer system then can move on the microscopic scale to relax tire applied stress. This effect is more pronounced at higher temperatures. The elastomeric film made without ZnO shows this effect also at lower temperatures. This result is evidence for the self-healing properties of the elastomeric film described herein.

Recycling of the elastomeric films

A number of elastomeric films were recycled and the tensile strength values for the initial elastomeric films were compared with the tensile strength values for the recycled films.

Example 12: (comparative} and 13-15

The samples for the tensile test were cut from a film prepared in accordance with

Example 5-8, using a Type 2 dumbbell cutter die, as specified in ISG37 (5* edition, 2011- 12-15). The ends of the dumbbell were placed in the jaws of the Hounsfie!d HK10KS Tensiometer fitted with an H500LC extensometer and subjected to strain rate of 500mm per minute. The value for the stress was reported automatically by the machine software, as was the modulus value at a given strain {typically 100, 300 and 500% strain). The results are reported in Table 2. Table 2

Recycling of the elastomeric films

Herein, an elastomer film being recyclable is defined as one which upon being out up into small pieces can be recombined upon subjecting the pieces to a low temperature, typically less than 100°C for 1 minute, or preferably at 80°C for 5 minutes, under an applied pressure of 13.8 MPa (2000psi); which then demonstrates an elongation at break in excess of 90%. and a tensile strength of greater than 1.5 MPa in accordance with the following test protocols. Example 16: (comparative) The samples for the tensile test were prepared by re-combining cut-up samples of the dipped film produced from the compounded latex, Example 5 (comparative), (the original film being prepared in accordance with the protocol of Example 5), the mixture of small pieces was annealed between two polished steel plates before hot pressing at 13.8 MPa (200Gpsi) for 1 minute and 100°0, before being cooled to room temperature and then dumbbell shaped samples were cut out using the Type 2 die cutter specified in IS037 (5 ^th edition, 2011-12-15. The ends of the dumbbell were placed in the jaws of the Hounsfield HK10KS Tensiometer fitted with an H500LC extensometer and subjected to strain rate of 500mm per minute. The value for the stress was reported automatically by the machine software, as was the modulus value at a given strain (typically 100, 300 and 500% strain). The results are reported in Table 3.

Example 17:

This was an exact repeat of Example 16, except that Example 6 replaced Example 5; the results are reported in Table 3.

Example 18: (comparative)

This was an exact repeat of Example 16, except that the dumbbell sample was annealed at 13.8 MPa (200Qpsi) and 80°C for 5 minutes, cooled to room temperature and the ends of the dumbbell were placed in the jaws of the Hounsfield HK1 OKS Tensiometer fitted with an H500LC extensometer, and subjected to strain rate of 500mm/min. The value for the stress was reported automatically by the machine software, as was the modulus value at a given strain (typically 100, 300 and 500% strain). The results are reported in Table 3. Example 19

This was an exact repeat of Example 18, except that Example 6 replaced Example 3; the results are shown in Table 5.

Example 20

This was an exact repeat of Example 18, except that Example 8 replaced Example 5; the results are shown in Table 3.

Table 3

Table 3 shows that both of the comparative Examples (16 & 18) failed (dumbbells ruptured) at less than 100% strain and all showed a tensile strength of less than 1.5MF>a and an elongation at break of less than 90 strain; therefore, the comparative examples did not demonstrate the ability to self-heal at toe annealing temperature used.

The Examples 17 & 19 (no zinc oxide, pH 10.0) demonstrated a tensile strength in excess of 3 MPa and an elongation at break above 200%, after annealing at 100°C for 1 minute, or 80°C for 5 minutes. That is, the films produced from these dipped gloves were recyclable films.

Example 20 demonstrated that increasing toe pH to 11.5 increased toe tensile strength and the modulus, though the elongation at break was reduced to 139%. That is, the film produced from this dipped glove was a recyclable film. Determination of tensile properties after repairing an elastomeric film:

Nitrile latex with, or without compounding materials at the desired pH value was stirred for 3 hours at room temperature, and then cast on to a petri dish.

The cast latex film cm the surface of toe petri dish was then placed in a circulating air oven at 25 °C for three days. The obtained films were then annealed in an air circulating oven at 9G"C for 24 hours to ensure complete drying and any desired crosslink formation to occur.

The cast film was carefully removed from the glass petri dish and cut into dumbbell shapes using a 3mm TV-type cutter (see Fig. 1). One dumbbell was left uncut (to act as a control sample), whilst another was cut into halves at the middle point of the dumbbell (see Figure 2). If required, the upper surface of each of the cut halves was marked for reference. The freshly cut surfaces of the dumbbells were then immediately pressed together for 60 seconds (see Fig. 3) while the cut pieces were placed on a glass plate, and then these rejoined pieces on the glass plate were placed in an air circulating oven at 180°C for 30 minutes (to simulate a non-pressure dry rubber hot treatment process). Alternatively, the freshly cut surfaces of the dumbbells were then immediately pressed together for 60 seconds and the pressure maintained by placing the‘jaws' of a wooden peg over the rejoined sections, followed by heat treatment in an oven at 180’C for 30 minutes. This was intended to simulate a low-pressure dry rubber hot press process.

Example 21 (comparative)

A portion of the oxirane-free XNBR latex, Example 1, was adjusted to a pH value of 10 using an aqueous solution of potassium hydroxide, and compounded with 1 phr zinc oxide, 0.8 phr of Sulphur and 0.7 phr of ZDEC. The compound was then stirred for 3 hours and then cast on to a glass petri dish and allowed to dry at room temperature (25°C) for 3 days. The obtained film was removed from the glass petri dish and annealed in an oven at 90°C for 24 hours to ensure complete drying and crosslink formation.

Wherein a film which was cut into 2 halves and subsequently the 2 halves were then held together was capable of demonstrating a tensile strength when the thus joined 2 halves were subsequently separated, was said to be self-healing .

The two dumbbeii samples (cut-and-rejoinied and uncut) were then subjected to stress- strain analysis to determine the tensile properties of the elastomer before and after being cut-and-rejointed. That is, to determine the extent of self-healing of the cut film. The tensile properties were tested in accordance with ASTM D412-06a , using a 3 mm, type 'O' dumbbell specimen for tensile tests, with a typical film thickness of 1.0- 1.4 mm ± 0.01 cut from the cast latex film. The film thickness (mm) was measured using a thickness gauge (supplied by Syfvac, model, Studenroth, type 12.5mm/ 0.001 ).

A Zwick Roell Z005 TN Praline tensiometer fitted with a long stroke extensometer was used to record the tensile stress-elongation curves. The samples were extended at a rate of 500mm / minute, at a temperature of 23±2° C, and a relative humidity 50±5%. The Tensile Strength data reported here corresponds to the observed maximum tensile stress whilst elongating the dumbbell to rupture. The reported Ultimate Elongation value corresponds to the elongation at which rupture occurred. The reported Modulus values, M ₁₀₀ , M ₃₀₀ and Ms» _, correspond to the stress required to reach an elongation of 100%, 300% or 500% of the original length, respectively. Preparation of dumbbell samples, and comparison of uncut and self-healed samples: Example 22:

A dried and cured film obtained from Example 21 was then cut in to a number of dumbbell samples using a‘D‘ cutter (see Fig. 1). One dumbbell remained uncut whilst another was cut into halves using a sharp blade applied to the narrow section of the dumbbell (see Fig. 2). The cut dumbbell was then immediately re-joined by holding the cut surfaces together and manually pressed together for 60 seconds (See Fig.3). The thus rejoined dumbbell was then annealed in an air-circulating oven, maintained at 180°C. for 30 minutes. The self-healed dumbbell was then subjected to a tensile test in order to determine the extent of recovery of the tensile properties by comparison to the results obtained for the uncut dumbbell obtained from the same cast film.

The results are shown in Table 4 and Figure 7.

Example 23

To an aliquot of Example 1 (the oxirane-free XNBR latex) was added an aliquot of

Example 2 (the oxirane-functional latex), such that She blending ratio was 90:10 by weight wet of Example 1 : Example 2. The blend was adjusted to a pH value of 10 using a solution of potassium hydroxide and stirred for 3 hours and then cast on to a glass petri dish and allowed to dry at room temperature (25°C) for 3 days. The obtained film was removed from the glass petri dish and annealed in an oven at 90°C for 24 hours to ensure complete drying and crosslink formation. The film was then cut into dumbbells and tested, as per Example 22,

The results are shown in Table 4 and Figure 8. Example 24

This was a repeat of Example 23, except that 1 phr zinc oxide was added to the latex, at pH 10, and stirred for 3 hours before casting. The film was then cut into dumbbells and tested, as per Example 22.

The results are shown in Table 4 and Figure 9.

Example 25

This was a repeat of Example 23, except that the pH value was adjusted to 11.5. The film was then cut into dumbbells and tested, as per Example 22.

The results are shown In Table 4 and Figure 10.

Table 4

Example 26

To an aliquot of Example 1 (the oxirane-free XNBR latex) was added an aliquot of Example 2 (the oxirane-functional latex), such that the blending ratio was 90:10 by weight wet of Example 1 : Example 2.

The blend was adjusted to a pH value of 5 using an aqueous solution of potassium hydroxide and stirred for 3 hours and then cast on to a glass petri dish and allowed to dry at room temperature (25°C) for 3 days. The obtained film was removed from the glass plate and annealed in an oven at 90°C for 24 hours to ensure complete drying and crosslink formation. The dried and cured film was then cut in to a number of dumbbell samples using a‘D’ cutter. One dumbbell remained uncut whilst another was cut into halves using a sharp blade applied to the narrow section of the dumbbell. The cut dumbbell was then immediately re-joined by holding the cut surfaces together and manually pressed together for 60 seconds, this was immediately followed by the application of the jaws of a wooden clothes peg to maintain the intimate contact of the 2 surfaces as the thus rejoined dumbbell was annealed in an air-circulating oven, maintained at 180°C, for 30 minutes. The results are shown in Table 5.

Example 27

This was a repeat of Example 26 except teat tee pH value was adjusted to 10. The results are shown in Table 5.

Example 28

This was a repeat of Example 26, except teat tee pH value was adjusted to 11. The results are shown in Table 5.

Example 29

This was a repeat of Example 26, except that the pH value was adjusted to 11.5. The results are shown in Table 5,

Tables