MOISTURE-CURABLE SILYLATED POLYMERS FOR FAST MOISTURE CURING COMPOSITIONS

FIELD OF THE INVENTION

[00011 The present invention relates to a method of preparing moisture-curable silylated polymers by reacting amino- or carboxy-terminated polymers with silanes containing methylenehydrocarbyloxysilanes, and to the compositions formed thereby. In particular, the inventive compositions possess fast moisture-cure capabilities.

BACKGROUND OF RELATEDTECHNOLOGY

[0002] Alkoxy-terminated polysiloxanes have been used to prepare moisture-curable silicone adhesives with desirable properties. These reactive polysiloxanes are typically prepared by endcapping silanol-terminated silicones with alkoxysilanes which are capable of functioning as crosslinkers The endcapped silicones may then be cured (i.e. cross-linked) by exposure to ambient conditions in the presence of a catalyst and/or heat.

[0003] Various methods have been developed to increase cure speed or lower the heat necessary for such a cure. Among them is the use of methylenealkoxysilanes, in which the - Ctfe- group connected to the hydro carbyloxysilane silicon confers increased cure speed and low temperature cure abilities to the composition.

[0004] However, this methodology has traditionally been restricted' to siloxane polymers.

There is a need for similar low-temperature, rapid moisture-cure ability in non siloxane polymers, such as polyethers, polyamides, polycarbonates, and the like.

SUMMARY OF THE INVENTION

[0005] The present invention provides a method of using a wide range of polymers to prepare compositions capable of rapid moisture cure at relatively low temperatures, and to the compositions resulting from such a method.

[0006] In one aspect of the present invention, there is provided a composition which includes a moisture-cure functionalized polymer which contains at least one moisture curable group having the structure:

Formula (VI)

[0007] In another aspect of the present invention, there is provided a composition which includes a polymer of Formula (I):

(R ¹ O) ₃ . _a Si CH ₂ Q ¹ Z Q ² — CH ₂ Si (R ¹ O) _3-1

R a R a

Formula (I)

[0008] In still another aspect of the present invention, there is provided a composition which includes at least one polymer selected from:

(R ¹ O) ₃ . _a Si-CH ₂ -N Z N-CH ₂ -Si (R ¹ O) _3-3

R ² _a R ³ R ³ R ² _a

(A);

(B); and

(C).

[0009] In a further aspect of the present invention, there is provided a method for making a composition, the method including the step of mixing:

a) a compound of Formula (II):

(II); and

b) a polymer of Formula (III) :

H — N Z N — H

R ³ R ³

Formula (III)

[0010] In still another aspect of the present invention, there is provided a composition which includes the reaction product of:

a) a compound of Formula (II):

Formula (II); and

b) a polymer of Formula (III) :

Formula (III)

{0011] In yet another aspect of the present invention, there is provided a method of making a composition, the method including the steps of mixing:

a) a compound of Formula (IV):

Formula (IV); and

b) a polymer of Formula (V) :

O O

_R 6_ _o — _c — £ — _c — _o — _R 6

Formula (V)

[0012] In another aspect of the present invention, there is a provided a composition which includes the reaction product of:

a) a compound of Formula (IV) :

Formula (IV); and

b) a polymer of Formula (V):

O O

R ⁶ — O — C Z C — O R ⁶

Formula (V)

[0013] In still another aspect of the present invention, there is provided a method of using a composition, the composition including a polymer of Formula (I):

(R ¹ O) _3-3 — Si CH ₂ — Q ¹ Z Q ² — CH ₂ — Si (R ¹ O) _3-3

K a ^κ a

Formula (I)

the method including the steps of:

a) providing the composition;

b) applying the composition onto a substrate; and

c) permitting the composition to cure.

[0014] In the above representations,

R ¹ in each occurrence may be the same or different, and is a Ci to Qo hydrocarbon radical;

R ² in each occurrence may be the same or different, and is a Ci to Cio hydrocarbon radical;

R ³ in each occurrence may be the same or different and may be selected from H and a Ci to Cio hydrocarbon radical; and

R ⁴ in each occurrence may be the same or different and may be selected from H and Ci to C4 alkyl;

R ⁵ may be selected from H and a Ci to Cio hydrocarbon radical;

R ⁶ may be a selected from H, a Ci to Ci ₀ hydrocarbon radical, an organic cation and an inorganic cation;

Q ¹ may be selected from:

Q ² may be selected from:

X may be selected from halogen;

O

R ₅ ⁵ — C Ii O-

Y may be selected from halogen and O R 5 ⁵ — C 'I — O

Z is a divalent polymer; and a is 0 or 1.

DETAILED DESCRIPTION

[0015] The present invention provides hydrocarbyloxysilyl-functionalized polymers capable of rapid moisture cure.

[0016] As used herein, the term "hydrocarbon radical" is intended to refer to radicals primarily composed of carbon and hydrogen atoms. Thus, the term encompasses aliphatic groups such as alkyl, alkenyl, and alkynyl groups; aromatic groups such as phenyl; and alicyclic groups such as cycloalkyl and cycloalkenyl. Hydrocarbon radicals of the invention may include heteroatoms to the extent that the heteroatoms do not detract from the hydrocarbon nature of the groups. Accordingly, hydrocarbon groups may include such functional groups as ethers, alkoxides, carbonyls, esters, amino groups, amido groups, cyano groups, sulfides, sulfates, sulfoxides, and sulfones.

[0017] The hydrocarbon, alkyl, and phenyl radicals of the present invention may be optionally substituted. As used herein the term "optionally substituted" is intended to mean that one or more hydrogens on a group may be replaced with a corresponding number of substituents selected from alkyl, alkenyl, alkynyl, aryl, halo, haloalkyl, haloalkenyl, haloalkynyl, haloaryl, hydroxy, alkoxy, alkenyloxy, alkynyloxy, aryloxy, carboxy, benzyloxy, haloalkoxy, haloalkenyloxy, haloalkynyloxy, haloaryloxy, nitro, nitroalkyl, nitroalkenyl, nitroalkynyl, nitroaryl, nitroheterocyclyl, azido, amino, alkylamino, alkenylamino, alkynylamino, arylamϊno, benzylamino, acyl, alkenylacyl, alkynylacyl, arylacyl, acylamino, acyloxy, aldehydo, alkylsulphonyl, aryisulphonyl, alkylsulphonylamino, arylsulphonylamino, alkylsulphonyloxy, arylsulphonyloxy, heterocyclyl, heterocycloxy, helerocyciylamino, haloheterocyclyl, •» alkylsulphenyl, arylsulphenyl, carboalkoxy, carboaryloxy, mercapto, alkylthio, arylthio, acylthio and the like.

[0018] As used herein, the terms "halo" and "halogen" are intended to be synonymous, and both are intended to include chlorine, fluorine, bromine, and iodine.

Inventive Compositions

[0019] Typical compositions of the invention include a moisture-cure functionalized polymer which contains at least one moisture curable group having the structure:

(R ¹ O) ₃ . _a — -St-CH ₂ -Q ¹ — I

Formula (VI)

[0020] Moisture-cure functionalized polymers suitable for use in the present invention are those obtained from silicones, polyethers, polyesters, polyamides, polyimides, polyacrylates polyalkylenes, polyvinyls, polycarbonates, and mixtures thereof. The polymer may be a copolymer, thus having more than one type of repeating monomelic unit. The copolymer may be a random copolymer, block copolymer, or alternating copolymer. In an advantageous aspect the polymeric unit includes polymers selected from silicones, polyethers, polyesters, polyamide: and polyalkylenes.

[0021] At least one moisture curable group of Formula (VI) must be attached to the polymer. The groups of Formula (VI) may be attached to the polymer in pendant position, terminal positions, or combinations thereof.

[0022] R ¹ in each occurrence may be the same or different, and is a C ₁ to Cio hydrocarbon radical. Substituent R ¹ , in combination with the oxygen to which it is attached, forms a hydrolyzable group, which provides the compositions of the present invention with then ability to undergo room temperature vulcanization (RTV). RTV cure typically occurs through exposure of the compositions of the present invention to moisture. The presence of hydrolyzabl moisture curing groups such as alkoxy groups, permits the compositions of the present invention to undergo moisture cure. Suitable hydrolyzable groups include alkoxy groups such as methoxy ethoxy, propoxy, and butoxy; acyloxy groups such acetoxy; aryloxy groups such as phenoxy; oximinoxy groups such as methylethylketoximinoxy; enoxy groups such as isopropenoxy; and alkoxyalkyl groups such as CH3OCH2CH2-. Larger groups such as propoxy and butoxy are slower to react than smaller groups such as methoxy and ethoxy. Accordingly, the rate at which

the compositions of the invention undergo moisture cure can be influenced by choosing appropriately sized groups for substituent R ¹ . Desirably, R ¹ is Ci to C ₄ alkyl or phenyl. More desirably, R ¹ is methyl or ethyl.

[0023] R ² in each occurrence may be the same or different, and is a Ci to Cio hydrocarbon radical. Desirably, R is Cj to C4 alkyl or phenyl. More desirably, R is methyl or ethyl.

[0024] Q ¹ is selected from:

[0025] Q ² is selected from:

[0026] R ³ is selected from H and a Ci to Cio hydrocarbon radical.

10027] R ⁴ is selected from H and Ci to C ₄ alkyl. Advantageously, R is H or methyl.

[0028] In one aspect, the inventive compositions include a polymer of Formula (I), in which the moisture cure-groups are located in a terminal position:

(R ¹ O) ₃ . _a Si CH ₂ Q ¹ Z Q ² — CH ₂ Si (R ¹ O) _3-3

R ² _a R =>2 a

Formula (I)

[0029] Z is a divalent polymer, and forms the polymer of the polymer of Formula (I).

Examples of suitable divalent polymers are those obtained from silicones, polyethers, polyesters, polyamides, polyimides, polyacrylates, polyalkylenes, polyvinyls, polycarbonates, and mixtures thereof. The polymer may be a copolymer, thus having more than one type of repeating monomelic unit. The copolymer may be a random copolymer, block copolymer, or alternating copolymer. In an advantageous aspect, the polymeric unit includes polymers selected from silicones, polyethers, polyesters, polyamides, and polyalkylenes.

[0030] Variable "a" indicates the number of alkyl groups present on the silane silicone, and in each occurrence may be the same or different, and is 0 or 1. "3-a" indicates the number of alkoxy groups on the silane silicone.

[0031] In another aspect, the present invention provides compositions which include at least one polymer of the formulas:

(R ¹ O) ₃ ^ Si-CH ₂ -N — Z N-CH ₂ -Si — (R ¹ O) _3- ,,

R ² _B R ³ R ³ R ² _a

(A);

(B); and

(C); where R ¹ ; R ² ; R ³ ; and a are as described hereinabove, and R ⁵ may be selected from H and a Ci to C _1O hydrocarbon radical

[00321 The inventive compositions may include one or more moisture-cure catalysts.

Suitable moisture-cure catalysts include compounds which contain such metals as titanium, tin, or zirconium. Illustrative examples of the titanium compounds include tetraϊsopropyltitanate and tetiabutyl titanate. Illustrative examples of the tin compounds include dϊbutyltin dilaurate, dibutyltin diacetate, dioctyltindicarboxylate, dimethyltindicarboxylate, and dibutyltindioctoate. Illustrative examples of the zirconium compounds include zirconium octanoate. The moisture- cure catalysts are employed in an amount sufficient to effectuate moisture-cure, which generally is from about 0.05% to about 5.00% by weight, and advantageously from about 0.5% to about 2.5% by weight.

[0033] As discussed above, hydrocarbyloxy groups on the silicon atom permit the compositions of the present invention cure in the presence of moisture. Moreover, the hydrocarbyloxysilyl groups present in the polymer of Formula (I) are methylenehydrocarbyloxysilyl groups, in which the α carbon provides the hydrocarbyloxy groups with enhanced capacity as leaving groups. Because the compositions of the present invention ewe rapidly, they do not require moisture-cure catalysts to the extent that such catalysts are used with traditional RTV materials. Reducing the amount of moisture-cure catalyst may be desirable to prevent shelf-life problems. As the presence of any moisture in the packaging may lead to premature crosslinking and curing, the ability to use less moisture-cure

catalyst in the inventive compositions provides additionally stability without compromise of the cure speed.

[0034] A variety of additional useful components may be added to the present inventive compositions. For example vinyl trimethoxysilane may be added as a moisture scavenger. Other useful additives include plasticizers, fillers, viscosity modifiers, flow modifiers, pigments, stabilizers, inhibitors, adjuvants, catalysts, accelerators, thixotropic agents and combinations thereof. These additives should be present in amounts suitable to effectuate their intended purpose.

Preparation of the Inventive Compositions

[0035] The present invention also provides methods for preparing compositions which include a moisture-cure functionalized polymer. In each case, hydrocarbyloxysilyl-containing polymers are prepared by reacting amine- or carboxy-containing polymers with silanes which contain hydrocarbyloxysilylmethylene groups, thereby producing the moisture-cure functionalized polymer.

Pathway A: Amino-Containing Polymer Starting Material

[0036] One approach to preparing the moisture-cure functionalized polymer includes mixing: a) a compound of Formula (II):

Formula (II); and

b) a polymer which includes at least one group having the structure:

wherein the polymer, R ¹ , R ² , R ³ , and a are as discussed hereinabove.

X may be selected from halogen;

O

R B ⁵ — C 'I — O-

[0037] R ⁴ may be selected from H and Ci to C ₄ alkyl. Advantageously, R ⁴ is hydrogen.

[0038] R ⁵ may be selected from H and a Ci to Cio hydrocarbon radical

[0039] When X is a halogen, the reaction will advantageously take place in the presence of a basic component, which facilitates the reaction and neutralizes any acids formed during the course of the reaction. Any suitable inorganic base or organic base may be used to promote the reaction. Organic bases useful in the present invention include amines such as trialklyamines such as triethylamine, and Hunig's base. Inorganic bases useful in the present invention include metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide; metal carbonates such as sodium carbonate; and metal alkoxides such as sodium ethoxide and potassium ethoxide.

[0040] In one aspect, the method relates to the preparation of compositions which include polymers of Formula (I). The method includes mixing a compound of Formula (II) with an amino end-capped polymer of Formula (III):

a) a compound of Formula (II) :

Formula (II); and

b) a polymer of Formula (III):

Formula (III)

wherein R ¹ , R ² , R ³ , X ₅ Z, and a are as discussed above.

[0041] As shown below in Scheme 1, the method may take the form of an amine- containing polymer reacting with a halomethylhydrocarbyloxysilane (such as the chloromethylalkoxysilane shown in Scheme 1):

Scheme 1 (R ¹ O) _3-3 - H

[0042] In another aspect, the moisture-cure functionalized polymer may be formed via a

Michael addition, as shown in Scheme 2:

Scheme 2

H

[0043] In a further aspect, the method may take the form of an amine-containing polymer reacting with an acetoxymethylsilane. In such a reaction, different coupling products are possible. For example, Scheme 3 shown below shows an amine end-capped polymer reacting with an hydrocarbyloxyacetoxymethylsilane. One possible pathway resulting in each of the nitrogens displacing the acetoxy group, resulting in polymer (A). Another possible pathway results in the nitrogens each replacing one or more hydrocarbyloxy groups on a silicon atom, as is exemplified by polymer (B). In another variation, one of the nitrogens replaces an acetoxy group, and the other nitrogen replaces a hydrocarbyloxy group, resulting in polymer (C).

Scheme 3

Pathway B: Carboxy Containing Polymer Starting Material

[0044] The moisture-cure functionalized polymer may also be obtained by mixing:

a) a compound of Formula (IV):

Formula (IV)

b) a polymer which includes at least one group having the structure:

wherein R ¹ , R ² , R ⁶ , and a are as discussed hereinabove.

Y may be selected from halogen and

O

₅ Il

R ⁵ — C O-

[0045] R ⁵ may be selected from H and a Ci to Cio hydrocarbon radical.

[0046] R ⁶ may be selected from H, a Ci to Qo hydrocarbon radical, an organic cation and an inorganic cation. Organic cations suitable for use in the present invention include quaternary nitrogens, such as those which contain a nitrogen atom bearing four alkyl or hydrogen substituents. Illustrative of the inorganic cations suitable for use in the present invention are alkali metal cations, such as those of lithium, sodium, and potassium.

[0047] In one aspect, the invention provides a method for producing compositions which include a polymer of Formula (I). The method includes the step of mixing:

a) a compound of Formula (IV):

Formula (IV); and

b) a polymer of Formula (V):

O O

R ⁸ — O — C Il — Z — C Il — O — R ⁶ Formula (V)

wherein R , R , Z, Y, and a are as discussed hereinabove.

[0048] As shown below in Scheme 4 the polymer of Formula (I) may be obtained by reacting a halomethylhydrocarbyloxysilane (such as the chloromethylalkoxysilane shown in Scheme 4 with a carboxy containing polymer:

Scheme 4 o o

(R ¹ O) ₃ ^-Si-CH ₂ -CI + R ⁶ — O— C — Z — C— -O— R ⁶ R ²

[00491 In cases such as this, where Y is halogen, R ⁶ is advantageously a member selecte from the group consisting of an organic cation and an inorganic cation. Such a starting material may be obtained, for example, by reacting a carboxylic acid containing polymer with a basic component, such as alkali metal hydrides, hydroxides, and alkoxides.

[0050] The moisture-cure functionalized polymer may also be obtained by reacting a carboxymethylenesilane with a carboxy-containing polymer, as shown in Scheme 4, using an appropriate catalyst such as the tin or titanium catalyst, such as those discussed hereinabove as moisture-cure catalysts.

Scheme 5

O O O

(R ¹ O) ₃ - _S -Si-CH ₂ -O-C — R ⁵ + R ^s — O— C — Z — C-O — R ⁶

Uses of the Inventive Compositions

[0051] The inventive compositions can be used in a variety of applications, including those where the ability to quickly moisture-cure is necessary. Illustrative examples of such uses include use as a sealant, use as an adhesive, gasketing, and potting applications. In one aspect, a method of using a composition of the invention includes the steps of:

a) providing the composition;

b) applying the composition onto a substrate; and

c) permitting the composition to cure,

wherein the composition is as described hereinabove.

[0052] The compositions may be used, for example, to seal or bond substrates, such as, but not limited to, gaskets. In gasketing applications, the moisture curable composition may be applied to one of the substrates which will form part of the gasket, cured or at least partially cured, and then joined to a second substrate to form a gasket assembly. Such gasketing applications include, for example, form-in-place gaskets. For instance, the compositions may be applied to a substrate and subjected to curing conditions. The compositions may be used to seal together substrates by applying the composition to at least one of two substrate surfaces, mating

the substrate surfaces in an abutting relationship to form an assembly, and exposing the ccoommppoossiittiioonn ttoo mmooiissttuurree ttoo eeffffeecctt ccuurree.. TThhee ssuutbstrates should be maintained in the abutting relationship for a time sufficient to effect cure.

EXAMPLES

{0053] Illustrative procedures for preparing compositions of the invention are shown below.

Example 1

[0054] An ethylaminoisobutyldimethyloxysilyl terminated polydimethylsiloxane (506g) containing 0.4546 meq/g amine was placed in a 1 liter reaction kettle. Triethylamine (23.33g), and chloromethyltrimethoxysilane (39.39g) were further added with mixing. The mixture was heated to 50 ⁰ C to 6 hrs. During that time, a white solid formation of triethylamine hydrochloride was observed. An aliquot of the solid liquid mixture was withdrawn and placed in an aluminum dish. The mixture formed a non-tacky skin in 5 minutes. The mixture in the reaction kettle was further stirred at room temperature for 5 days followed by vacuum filtration to remove the solid. An aliquot of the clear filtrate was withdrawn and placed in an aluminum dish. The liquid formed a non-tacky skin in 30 seconds and cured to a dry solid in a few hours. In comparison, the ethylaminoisobutyldimethoxysilyl terminated polydimethylsiloxane exhibited no skin formation even after several hours when exposed in ambient conditions.

Example 2

{0055] An aminopropyldimethoxysilyl terminated polydimethylsiloxane (197.45g) containing 0.4435 meq/g amine was placed in a 500 ml round bottom flask. Triethylamine (8.84g) and chloromethyltrimethoxysilane (14.93 g) were further added with mixing. The mixture was heated to 90 ⁰ C for 7hrs. During that time, a white solid formation of triethylamine hydrochloride was observed. The mixture was vacuum filtered to remove the solid. An aliquot of the filtrate was placed in an aluminum dish and exposed to ambient conditions. The filtrate formed a tacky skin in 5 seconds and cured to a solid in a few hours. In comparison, the amiiiopropyldimethoxysilyl terminated polydimethylsiloxane exhibited no skin formation even after several hours exposure in ambient conditions.

Example 3

[0056] An aminopropyldimethoxysilyl terminated polydimethylsiloxane (134.76g) containing 0.4435 meq/g amine was mixed with acetoxymethyltriethoxysilane (14.1Og) in a 300 ml round bottom flask. The mixture was heated to 60 ⁰ C for 6 hours. The mixture, after standing overnight under nitrogen, exhibited a skin over a time of 5 minutes. The mixture was further heated to 80 ⁰ C for another 6 hours. The mixture then exhibited a skin over time of 1 minute and cured to a solid overnight.

Example 4

[0057] 10Og of an amine-terminated polyoxypropylene diol (Jeffamine XTJ-510 from

Huntsman Corporation) containing 0.48 meq/g amine was placed in a 300 mL round bottom flask. Triethylamine (4.85 g) and chloromethyltrimethoxysilane (8.18g) were successively added. The mixture was heated to 80 ⁰ C for 6 hours with vigorous stirring. A white solid triethylamine hydrochloride formation was observed. An aliquot of the solid liquid mixture was withdrawn and placed in an aluminum dish. The mixture formed a non-tacky skin less than 10 seconds and cured to a solid in a few hours.

Example 5

[0058] In a 500 mL 3-necked reaction kettle was placed 181.50 g of Hycar ATBN

1300X42 (an amine terminated polybutadiene-acrylonitrile copolymer from Noveon). Triethylamine 40.74 g and chloromethyltrimethoxysilane 68.20 g were then sequentially added with stirring. The mixture was further heated to 90 ⁰ C under nitrogen blanketing with stirring for 4.5 hours, during which time an insoluble salt formation of triethylammonium chloride was observed. An aliquot of the mixture was placed in an aluminum dish and exposed to ambient conditions. It showed a skin formation of <10 seconds and several millimeter depth of cure overnight.

Example 6

[0059] In a 500 mL 3-necked reaction kettle was placed 203.35 g of Hycar CTB

2000X162 (a carboxylic acid terminated polybutadiene from Noveon). A 21% solution of

sodium ethoxide in ethanol (29.81 g) was added with vigorous mixing under nitrogen blanketing. The mixture turned very thick and became opaque in appearance. Chloromethyltrimethoxysilane (15.69 g) was further added with vigorous mixing. The mixture was heated at 7O ⁰ C with mixing for 5 hours. An aliquot of the mixture was placed in an aluminum dish and exposed to ambient conditions. It showed a skin formation of 10 seconds and several millimeter depth of cure overnight.

Example 7

[0060] A 20% toluene solution of Nucrel 599 (an ethylene-methacrylic acid copolymer from DuPont) was prepared by dissolving 45 g of Nucrel 599 in 180 g of anhydrous toluene at 80 ⁰ C in a 500 mL reaction vessel. The solution was heated to 90-100 ⁰ C under nitrogen with stirring. A 21% sodium ethoxide solution in ethanol (9.43 g) was then added with vigorous stirring for 10 minutes. Chloromethyltriethoxysilane (6.18 g) was further added at 90 ⁰ C. The mixture was further reacted for 3 hours at 90-100 ⁰ C. Dibutyltindilaurate (0.1 g) was added with stirring.

[0061] The solution, while still warm, was poured into a Teflon mold to form a film upon cooling. The film was allowed to undergo solvent evaporation and curing at room temperature for 1 week. Unlike Nucrel 599 itself which melted at 98°C, the film did not melt even upon heating to >150°C when compared side by side with Nucrel 599. The physical properties of this cured film was compared with Nucrel 599 as shown below:

[0062] The room temperature cured sample derived from Nucrel 599 clearly showed higher tensile strength and modulus but lower elongation due to crosslinking.