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Title:
A PROCESS TO REMOVE BAD SMELL AND ODOURS FROM PLASTIC MATERIALS
Document Type and Number:
WIPO Patent Application WO/2018/047205
Kind Code:
A1
Abstract:
A process to remove bad odours from plastic materials is disclosed, wherein said materials contain at least a polymer and at least a plasticiser. According to the process, natural or synthetic mono-, linear, branched or cyclic oligomeric carbohydrates are added during the compounding of the plastic formulation in order to fulfill the above indicated aim. The process is particularly suitable when said polymer is a polyvinyl chloride resin (PVC), chosen so as to exhibit a K value in the range K50-K85, and preferably in the range K64-K80. The invention also relates to a plastic material, containing at least a polymer and at least a plasticiser, on which natural or synthetic, mono-, linear, branched or cyclic oligomeric carbohydrates are grafted, once the formulation compounding already happened.

Inventors:
ZANICHELLI ANDREA (IT)
TAMBURELLO DAVIDE (IT)
JICSINSZKY LASZLO (HU)
ROSETTI LUCA (IT)
CRAVOTTO GIANCARLO (IT)
MARTINA KATIA (IT)
CAMPORASO MARINA NUNZIA (IT)
Application Number:
PCT/IT2016/000208
Publication Date:
March 15, 2018
Filing Date:
September 09, 2016
Export Citation:
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Assignee:
RESILIA S R L (IT)
International Classes:
C08B37/16; C08F259/04; C08J5/18; C08J7/12; C08K5/00; C08K5/12; C08L5/16; C08L27/06
Domestic Patent References:
WO2002094964A22002-11-28
Foreign References:
US20040110901A12004-06-10
Attorney, Agent or Firm:
VATTI, Francesco Paolo (IT)
Download PDF:
Claims:
CLAIMS

1) Process to remove bad smells and odours from plastic materials, wherein said materials contain at least one polymer and at least one plasticiser, characterised in that natural or synthetic mono-, linear, branched or cyclic oligomeric carbohydrates are added to the plastic formulation.

2) Process as claimed in claim 1) , characterised in that said polymer is a polyvinyl chloride resin, chosen so as to exhibit a K value in the range K50-K85 and preferably in the range K64-K80.

3) Process as claimed in claim 1) or 2) , characterised in that such at least one plasticiser is chosen within the group including phthalic anhydride derivatives, mono- and di- esters of benzoic acid, esters of aliphatic and aromatic dicarboxylic acids, phosphoric acid esters, phenyl-esters of alkyl-sulphonic acids, citric acid esters, trimellitic anhydride derivatives, vegetable oils and epoxidised products, oligomeric C3-C6 chain esters and polymeric esters.

4) Process as claimed in claim 3) , characterised in that said at least one plasticiser is chosen within the group consisting of C3-C6 orthophthalates, both cyclic and acyclic, C7-C9 orthophtalates, linear C11-C13 alcohol derivatives, C6-C10 n- alkylphthalates , C7-C13 iso-alkylphthalates and butyl derivatives; adipates, sebacates, azelates and cyclohexanoates , aro- matic esters, terephthalates ; tri-2-ethylhexyl-trimellitate, tri-n-butyl-trimellitate, tri-n-octyl-trimellitate, tri-iso- octyl-trimellitate , tri-n-nonyl-trimellitate, tri-n-decyl- trimellitate, linear C8-C10 alcohol derivatives and mixed C7-C10 esters of trimellitic anhydride; epoxidised oils, epoxidised soybean oil (ESBO) and epoxidised linseed oil (ELO) .

5) Process as claimed in any claim 1) to 4) , characterised in that said oligomeric carbohydrates are chosen within the group consisting of linear or cyclic oligomers of organic molecules .

6) Process as claimed in claim 5) , characterised in that said oligomeric carbohydrates are oligomers of carbohy- drates chosen within the group consisting of glucose, mannose, allose, altrose, rhamnose, xylose or fructose.

7) Process as claimed in claim 6) , characterised in that said oligomeric carbohydrates are derivatised or not-derivatised forms of natural or synthetic cyclodextrins or cyclofructins .

8) Process as claimed in any previous claim, characterised in that carbohydrates are chemically, enzymatically or biochemically modified, either through acylation or through replacement of an oxygen atom of the carbohydrate with another at- om, chosen among nitrogen, sulfur and/or selenium.

9) Process as claimed in any previous claim, characterised in that oligomeric carbohydrates have a number of monomeric units ranging from 1 to 10, preferably from 5 to 10.

10) Process as claimed in any previous claim, character- ised in that carbohydrates are either compounded together with the polymer and its additives or are grafted to the finished plastic material.

11) Plastic material, containing at least one polymer and at least one plasticiser, characterised in that natural or syn- thetic mono-, linear, branched or cyclic oligomeric carbohydrates are added thereto.

12) Plastic material as claimed in claim 11) , characterised in that said at least one polymer is a polyvinyl chloride resin, chosen so as to exhibit a K value in the range K50-K85 and preferably in the range K64-K80.

13) Plastic material as claimed in claim 11) or 12) , characterised in that such at least one plasticiser is chosen within the group including phthalic anhydride derivatives, mono- and di- esters of benzoic acid, esters of aliphatic and aromatic dicarboxylic acids, phosphoric acid esters, phenyl -esters of al- kyl-sulphonic acids and some sulfonamides, citric acid esters, trimellitic anhydride derivatives, vegetable oils (epoxidised, hydrogenated and acetylated ones) and other acetylated mono- glycerides and epoxidised products, oligomeric C3-C6 chain es- ters and glycols/polyethers and polymeric plasticisers (various polyesters, polymeric adipates and polybutene) . 14) Plastic material as claimed in any claim 11) to 13) , characterised in that said oligomeric carbohydrates are oligomers of carbohydrates chosen within the group consisting of glucose, mannose, allose, altrose, rhamnose, xylose or fructose.

15) Plastic material as claimed in claim 14) , characterised in that said oligomeric carbohydrates are derivatised or not-derivatised forms of natural or synthetic cyclodextrins or cyclofructins .

16) Plastic material as claimed in any claim 11) to 15) , characterised in that the concentration of carbohydrates in the final formulation ranges between 0.1 and 20 wt.%, based on the total weight of the polymer in the formulation, preferably between 0.1 and 10 wt.% based on the total weight of polymer in the formulation, in the most preferred way between 1 and 7 wt.%, based on the total weight of polymer in the formulation.

17) Plastic material as in claimed any claim 11) to 16) , characterised in that it further includes one or more stabilisers and/or one or more co- stabilisers and/or one or more lubricants and/or one or more gelling agents and/or one or more anti- sticking components and/or one or more inorganic or organic pigments or other colour components and/or one or more anti -oxidant components .

18) Plastic material as claimed in any claim 11) to 17) , characterised in that it includes K70 PVC resin, mixture calcium distearate - zinc stearate - ESBO, deodourised ESBO, DEHT/DOTP, EBS, pentaerythritol-tetrakis-3 - (3 , 5-di-tert-butyl-4- hydroxyphenyl ) propionate and an average percentage of 5 wt%, based on the total weight of K70 PVC, of peracetylated β- cyclodextrins .

Description:
A PROCESS TO REMOVE BAD SMELL AND ODOURS FROM PLASTIC MATERIALS

DESCRIPTION FIELD OF THE INVENTION

This invention refers to a process to remove bad smells and odours from plastic materials. This process can particularly be applied to the production of polyvinyl chloride (PVC) , although not exclusively thereto.

BACKGROUND OF THE INVENTION

The first plastic material was synthesised in 1861. Since then, plastic materials have become very important in industry. They can be used for many applications, in many technical fields. A few examples are bags, shoppers, automotive parts, toys, but also boats, clothing, pens, glasses and so on. A particularly important application is the use of PVC for medical devices, which can be easily sterilised.

Plastics are normally produced by polymerising some organic compounds, usually having unsaturated positions thereon, so as to create very long molecular chains, formed by a huge number of repeating units. For instance, polyethylene, one of the simplest polymers, is synthesised starting from ethylene (CH 2 = CH 2 ) , resulting in molecular chains, like - (CH 2 -CH 2 ) n - , where n is an integer which uses to be very high (even 1,000 or more) .

The polymerisation process usually gives rise to polymer flakes precipitating in the reaction solution. Such flakes can be extruded and then molten into a fuse which can be moulded within a mould, for instance through a process of injection moulding, so as to produce the final product by extracting it from the mould.

Many plastic materials are, however, too stiff for the purposes of their production. In such cases, it is advisable to add a plasticiser to the plastic material at a stage of its pro- cessing (from polymerisation to moulding) .

Focussing in particular on PVC, it can be used for pipes, medical devices, textile fibers, food packaging materials and other housewares, interior decorations, toys etc., and it is normally manufactured from a PVC resin, by mixing and dissolving it, upon heating, with a low molecular weight liquid plasticiser and then being moulded and cooled. Known low molecular weight liquid plasticisers are, for example, phthalate ester based plasticisers, phosphates, trimellitate esters, alkyl sulfonic acids esters and/or expoxidised soybean oil and may further include an anti-chlorine plasticiser.

Plasticisers, besides the positive effect to make plastic materials softer and more workable, have certain not-negligible drawbacks: they can migrate from the plastic, leaving the material itself (for instance, this happens within plastic bottles when their temperature reaches 60 °C and phthalates migrate within the mineral water contained therein) , or they can react with the environment and give rise to different compounds. It has been reported that the migration of plasticisers from PVC can reach the body of a plant or an animal, entering it and disrupting the normal activity of the endocrine system. This is surely harmful and sometimes even fatal .

The problem of plasticisers migration has been faced by numerous authors .

US 2009/286908 Al and US 2009/0281214 disclose the use of peracylated cyclodextrins to prevent the migration of plasticis- ers from plastic materials. The proposed mechanism involves the complexation of the plasticisers with the peracylated cyclodextrins. However, these documents say nothing about the removal of smells, taking into account that plasticisers are usually odourless, since the main ones have a low vapour pressure and, thus, are not characterised by odour. However, ageing, long term storage or high temperature treatments of plastic materials, result in characteristic (often bad) smells coming from the same plastic material. Many attempts have been performed to eliminate, or at least to alleviate, the problem related with the bad smell in the plastic materials. It is to point out that even the origin of such a smell is not completely understood up to now. Indeed, plastic materials include a large number of components. However, in various PVC based polymers, the common origin of smell is deemed basically to be 2-ethyl-l-hexanol . This compound forms through the hydrolytic cleavage of plasticisers . Anyway, the smell of such compound is not identical to the one issued by plastic materials, therefore other components are surely related to the origin of smell.

The attempt to remove oxidisers from the manufactured plastic materials gave only poor results, since objects are normally surrounded by air, which is itself, as it is well known, a powerful oxidiser.

In order to reduce the disturbing odour of polymeric materials, numerous attempts were patented, including the use of inorganic adsorbents (WO1992/013 029) , physicochemical treatment of polymers or intermediary materials (CA2 051 469, CN104 710 831, JPS60-135 403) or perfumisation of plastics with or without cyclic carbohydrates (CN104 292 697, EP2 311 502, JP2015 017 136, US5 578 563, WOOl/16 265, WO98/07 455) . All of these attempts showed that it is quite hard to remove the smell and, simultaneously, to keep the physicochemical properties of the polymeric composite unchanged.

SUMMARY OF THE INVENTION

The problem faced by this invention is to propose a method for removing bad odours from plastic materials, overcoming the above mentioned drawbacks and allowing to keep the physicochemical properties of the treated plastic material unchanged. This problem is solved by a process to remove the above bad smells and odours from plastic materials, wherein said materials con- tain at least one polymer and at least one plasticiser and is characterised by the addition in the formulation of natural or synthetic mono-, linear, branched or cyclic oligomeric carbohydrates. Sub-claim disclose embodiments of the invention. BRIEF DESCRIPTION OF DRAWINGS

Further features and advantages of the invention are better explained through the following detailed description of a preferred embodiment thereof, which is reported by way of example only and should not be understood as limiting the scope of protection of the invention.

In the annexed drawings :

Fig. 1 shows a comparison between spectra, obtained in gas chromatograph, of different compounds normally giving rise to bad odours; and

Figs. 2A-20 show NMR spectra of the same compounds, treated according to this invention.

BEST WAY TO CARRY OUT THE INVENTION

According to this invention, bad smells are removed from the plastic materials by adding natural or synthetic, mono-, linear, branched or cyclic, oligomeric carbohydrates to the plastic formulation. It has surprisingly been found that such carbohydrates are able to complex at least most of the substances which are usually responsible for bad odours and smells.

The addition of the above mentioned carbohydrates can take place at any stage of production of the plastic material . However, it is preferred to compound the carbohydrates together with the polymer and its additives (plasticisers , lubricants and others) or to graft them to the finished plastic material.

The process, according to this invention, can be used with any kind of plastic material, provided that it includes at least a polymer and at least a plasticiser. The process has proved particularly effective for polyvinyl chloride (PVC) , which is very versatile and wherein the problem of bad smells is particularly noticeable. Preferably, said at least one polymer is a polyvinyl chloride resin, chosen so as to exhibit a K value -a parameter describing the polymer length- in the range K50-K85 and preferably in the range K64-K80. Such range is a good compromise between mouldability and good physical properties.

The process has proved particularly effective for formula- tions containing plasticisers like phthalic anhydride deriva ¬ tives, mono- and di- esters of benzoic acid (respectively, ben- zoates, like INB (isononyl benzoate) and IDB (3- [[6- (3- carboxylato-2 , 4 , 6-triiodo-anilino) -6-oxo-hexanoyl] amino] -2,4,6- triiodo-benzoate) , and dibenzoates, like ODEB (1,2- diethoxybenzene, also oxydiethylene dibenzoate) and OXPDB (ox- ydipropyl dibenzoate) ) , esters of aliphatic and aromatic dicar- boxylic acids, phosphoric acid esters, phenyl-esters of alkyl- sulphonic acids (alkylsulphonates , like ASE (alkylsulphonic phenyl ester) ) and some sulfonamides, citric acid esters, trimellitic anhydride derivatives (trimellitates) , vegetable oils (epoxidised, hydrogenated and acetylated ones, like the mixture COMGHA, or acetylated monoglycerides of fully hydrogenated castor oil, and other acetylated monoglycerides) and other epoxidised products (like butyl -octyl-epoxystearate) , oligomeric C3-C6 chain esters (products of C3-C6 glycols and 1,2- dicarboxilic acid) and glycols/polyethers (like triethylene glycol dihexanoate (3G6, 3GH) and tetraethylene glycol diheptanoate (4G7) ) , and finally polymeric plasticisers (polyesters of hex- anedioic acid with alcohols and glycols, phthalic polyesters, caprolactone derived polyesters, polymeric adipates and poly- butene) .

Preferred phthalic anhydride derivatives are chosen in the group consisting of C3-C6 orthophthalates , both cyclic (DCHP (dicyclohexyl phthalate) and BCHP (butyleyelohexyl phthalate) ) and acyclic (phthalates of short-chain alcohols, like DMP (dime- thylphthalate) , DEP (diethyl phthalate) , DAP (diallyl phthalate) , DBP or DNBP (dibutyl or di-n-butyl phthalate) and DIBP (diisobutyl phthalate) , DPP or DNPP (dipentyl or di-n- pentyl phthalate) and DIHxP (diiso-hexyl phthalate) ) , C7-C10 or- thophtalates (like DEHP (bis (2-ethylhexyl) phthalate) or, more generically, DOP (dioctyl phthalate) and DPHP (bis (2- propylheptyl ) phthalate) ) , linear C11-C13 alcohol derivatives (like DUP (diundecyl phthalate) and DTDP (ditridecyl phthalate)), C6-C10 n-alkylphthalates (like DNHP (di-n-hexyl phthalate) and DNOP (di-n-octyl phthalate)), C7-C13 iso- alkylphthalates (like DIHpP (diisoheptyl phthalate) , DIOP (diisooctyl phthalate) , DINP (diisononyl phthalate) , DIDP (diisodecyl phthalate) , DIUP (diisoundecyl phthalate) , DITDP (diisotridecyl phthalate) ) , butyl derivatives (like BBP or BBzP (benzyl butyl phthalate) and BDP (butyl decyl phthalate) ) and other phthalates like ODP (octyl decyl phthalate) .

Preferred esters of aliphatic and aromatic dicarboxylic acids are chosen in the group consisting of aliphatic derivatives, such as adipates (DEHA (bis (2 -ethylhexyl ) adipate) or DOA (dioc- tyl adipate) above all, DMAD (dimethyl adipate) and MMAD (monomethyl adipate) , DINA (diisononyl adipate) , DIDA (diisodecyl adipate), DTDA (di (tridecyl) adipate)), sebacates (like DMS (dimethyl sebacate) , DBS (dibutyl sebacate) , DOS (di- octyl sebacate) ) , azelates (like DOZ (di-2 -ethylhexyl azelate) and DIDAz (di-2-isodcyl azelate) ) , maleates (like DBM and DIBM (dibutyl and diisobutyl maleate, respectively)) and cyclohexano- ates (like DINCH ( 1 , 2 -cyclohexane dicarboxylic acid diisononyl ester) ) , or aromatic esters, typically terephthalates (mainly DEHT (di-ethylhexyl terephthalate) or DOTP (dioctyl tereph- thalate) and also DBT (diisobutyl terephthalate) ) .

Preferred phosphoric acid esters are chosen in the group consisting of organophosphates , such as triphenyl phosphate (TPP) , 2-ethylhexyl diphenyl phosphate, tris (2-ethylhexyl) phosphate, tricresyl phosphate (TCP or TOCP, if tri-orthocresyl phosphate), tributyl phosphate (TBP) and tris- (2-ethyloxy) phosphate .

Preferred citric acid esters are chosen in the group consisting of alkyl citrates, especially ATBC (acetyl-butyl citrate) and BTHC (n-butyryl tri-n-hexyl citrate) and other PVC- compatible citrates (like THC (trihexyl citrate) , ATHC (acetyl trihexyl citrate), TMC (trimethyl citrate)) but also other ones, like TBC (tributyl citrate) , TEC / ATEC (respectively, triethyl and acetyl triethyl citrate) , TOC / ATOC (respectively, trioctyl and acetyl trioctyl citrate) .

Preferred trimellitic anhydride derivatives are chosen in the group consisting of tri -alkyl trimellitates, such as TMTM (trimethyl trimellitate) , TEHTM (tri- (2-ethylhexyl trimelli- tate) , generically known as TOTM) , tri-n-butyl-TM (C4-TM) , tri- n-octyl-TM and tri-iso-octyl-TM (C8-TM) , tri-n-nonyl-TM (C9-TM) , tri-n-decyl-TM (CIO-TM) , linear C8-C10 alcohol derivatives and mixed C7-C10 esters of trimellitic anhydride (like tri- (n-octyl , n-decyl) TM (ATM) and tri-(heptyl, nonyl) TM (LTM) ) ; n-octyl trimellitate (OTM) can also be used as plasticiser.

Preferred vegetable oil-base plasticisers are chosen in the group consisting of epoxidised oils, like epoxidised soybean oil (ESBO) and epoxidised linseed oil (ELO) , preferably in their de- odourised forms. Such oils are easily available on market.

Plasticisers can be either monomeric or polymeric, mono- or multi-substituted derivatives (especially esters) , and can have branched or linear C-chain (usually short-chain, the number of C atoms being normally in the range C3-C11) . Mixtures of C8-C10, C9-enriched, and of C9-C11, CIO -enriched, branched alkyl esters can be used in p-PVC formulations, as an example. Plasticisers are overall inserted in plastic materials, especially in p-PVC formulations, at a concentration ranging between 15 and 125 wt.%, based on the weight of polymer in the formulation. This range would ensure good plastic features.

Vegetable epoxidised oils can also be used as co- plasticisers , together with another plasticiser, at a concentration ranging between 0 and 20 wt.% based on the weight of polymer, since they have a stabilising effect on the final product.

Virtually, all natural or synthetic, mono-, linear, branched or cyclic, oligomeric carbohydrates can be added to the plastic material, in order to carry out the process according to this invention. Linear or cyclic oligomers of organic, carbohydrate molecules, such as glucose, mannose, allose, altrose, rhamnose, xylose or fructose, can be used to carry out the pro- cess, according to this invention, in a particularly effective way. Among them, derivatised or not-derivatised forms of natural or synthetic cyclodextrins (CD hereafter) or cyclofructins are the most preferred ones, due to their availability and cost. They are the best complexing agents. If cyclodextrin type is se- lected, α-, β- or γ-cyclodextrins are the most preferred ones.

Carbohydrates used within the scope of this invention can chemically, enzymatically or biochemically be modified, without departing from the scope itself. Modifications preferably include acylation of the carbohydrate or replacement of an oxygen atom of the carbohydrate with another atom.

Preferably, oxygen is replaced with nitrogen, sulfur and/or selenium.

In case of acylation of the carbohydrate, the acylation is performed through C0-C20 carboxylic acids. C0-C3 or ClO-16 car- boxylic acids are particularly preferred, among which acetic, propanoic, lauroic, stearic or myristoic acids proved particularly suitable. Any acylation method can be employed within the scope of this invention; however, the use of any natural form of ferric chloride and the parent homo- or mixed anhydrides, acid halogenides or activated carbonate esters is preferred.

The preferred oligomeric carbohydrates have a number of monomeric units ranging from 1 to 10, preferably from 5 to 10. This range gives rise to the best complexes with substances responsible for bad odours and smells.

The concentration of carbohydrates to be used in the final formulation ranges between 0.1 and 20 wt.%, based on the total weight of the polymer in the formulation, preferably between 0.1 and 10 wt.%, based on the total weight of polymer in the formulation, in the most preferred way between 1 and 7 wt.%, based on the total weight of polymer in the formulation. It has been shown that a carbohydrate concentration below 0.1 wt . % has no effect on the odour removal, whereas there is no further improvement for removal when the concentration is over 20 wt.%.

The plastic formulations can further include at least one among the following stabilisers: calcium distearate and zinc stearate (often used together in compounds, mixing them with ESBO and, possibly, anti-oxidant component like tris-nonylphenyl phosphite) , mixtures containing barium derivatives (C14-C18 fatty acids and C16-C18 unsaturated acids barium salts, barium carbonate, barium neodecanoate, barium m-toluic) together with naphtha, hydrotreated heavy components and isodecyl diphenyl phosphite (as anti-oxidant) , and aluminium-magnesium- zinc car- bonate hydroxide, zinc dibenzoate, C16-C18 fatty acids calcium salts and zinc salts, used as single components and, more often, as synergistic mixtures. Also a stabiliser chosen among tin- based stabilisers, usually a methyl- or octyl-based organotin compound, or Ca/Zn-base compounds can be used. Stabilisers can also be synergistic mixtures of metal soaps (Ca-Zn or Ba-Zn based) and properly developed co-stabilizers or "NGOB (Next Generation Organic Based) systems", based only on calcium soaps and organic co-stabilisers. Stabilisers are overall inserted in plastic formulations at a concentration in the range of 0.1 - 10.0 wt . % based on polymer weight, in particular, Ca/Zn and Ba/Zn mixtures can be used in a range of 0.5 - 4.0 wt . % based on polymer weight, while additional calcium and zinc salts (usually stearates) can be used in a range of 0.1 - 2.0 wt.% based on polymer weight.

Also one or more co- stabilisers can be employed. Among them, the already mentioned ESBO (co-stabiliser and co- plasticiser) , stearoyl benzoyl methane and an anti-UV component like didodecyl-1, 4 -dihydro-2 , 6-dimethylpyridine-3 , 5- dicarboxylate, in overall quantity in the range 0.01 - 1.0 wt.%, preferably 0.01- 0.5 wt%, based on polymer weight.

Moreover, lubricants such as C16-18 even amides (or other amides with an even number of C atoms) in particular Ν,Ν'- ethylenbis (stearamide) , mixtures containing palmitic acid and stearic acid together, partially fatty acid ester-mono/di- glyceril oleate, and polyadipate (fatty acid ester) , and of waxes such as paraffin and hydrocarbon waxes, polyethylene wax not oxidised and oxidised homopolymerical polyethylene wax (polyethylene wax with O containing functional groups) and other addi- tives, such as white mineral oil and hydrogenated castor oil, can be added. Lubricants can be used at an overall concentration in the range of 0.05 - 10.00 wt.% based on polymer weight and usually all the various types are present in different percentages for each type, but generically within a maximum concentra- tion of 2.0 wt.%; in particular, EBS (ethylene bis (stearamide) ) and palmitic and stearic acid mixtures can be used in the range 0.1 - 2.0 wt.% based on polymer weight, single waxes in the range 0.05 - 2.00 wt . % based on polymer weight and the other additives in the range 0.05 - 1.50 wt . % based on polymer weight.

The plastic material can further include gelling agents and antisticking components, consisting of acrylates and methacry- lates co-polymers that can be used in an overall range of 0.1 - 4.0 wt . % based on polymer weight.

Moreover, inorganic or organic pigments or other colour components can be added, such as masterbatches, titanium dioxide and optical brighteners (like 2 , 5-thiophene-diylbis (5-tert- butyl-l , 3 -benzoxazole) ) , at an overall concentration in the range 0 - 5.0 wt . % based on polymer weight. Preferably, pigments and optical brighteners are usually used at a low concentration, ranging for instance between 0.01 and 0.50 wt . % based on polymer weight for pigments and between 0 and 0.01 wt . % based on polymer weight for optical brighteners, while masterbatches and titanium dioxide can be typically used in the range 0 - 2.0 wt.% based on polymer weight. Inorganic and organic pigments often used are, for instance: polychloro copper phthalocyanine (Pigment Green 7), carbon black (Pigment Black 7), 8,18/9,19 dichloro-5 , 15- diethyl-5,15-dihydrodiindolo[3,2-b:3' ,2' -m] / [2,3-c:2' ,3'n] tri- phenodioxazine, sodium aluminosilicate violet (poly-sulfurized) , (poly) sulfurized aluminum- sodium salt of silicic acid.

Also anti -oxidant components can be added, in order to con- tribute to the reduction of bad odor emissions, especially phenol-based substances, such as pentaerythritol-tetrakis (3- (3 , 5- di-tert-butyl-4-hydroxyphenyl) propionate) and octadecyl-3 - (3 , 5- di-tert-butyl-4-hydroxyphenyl) propionate, and phosphites, like tris (nonyl -phenyl) phosphite and triisodecyl phosphite. Antioxi- dants can be used up to 2.50 wt.% based on polymer weight, if in combined use, and up to 1.50 wt.% based on polymer weight, if singularly used.

According to the above, an exemplary, preferred composition of the plastic material which can be obtained through this in- vention can include: K70 PVC resin, mixture calcium distearate - zinc stearate - ESBO (as a stabiliser) , deodourised ESBO (as a co-stabiliser and co-plasticiser) , DEHT/DOTP (as a plasticiser) , EBS (as a lubricant), pentaerythritol-tetrakis-3 - (3 , 5-di-tert- butyl-4 -hydroxyphenyl) propionate (as an antioxidant) and an average percentage of 5 wt%, based on the total weight of K70 PVC, of peracetylated β-cyclodextrins .

As it has been evidenced in the introduction, cyclodextrins were used to prevent the migration of plasticisers from plastic materials. However, according to this invention, carbohydrates protect plasticisers from decomposition, decelerate the further decomposition of fragments and reduce the emission of low molecular odour components from the manufacturing processes by entrapping them through complexation. This invention bases, i.a., on the finding that the small volatile molecules, deriving from plasticiser decomposition, form complexes with carbohydrates which are much more stable than the ones formed with the used plasticisers themselves, and so cyclodextrins are entrapping substances responsible for bad odours and smells and preventing them from further chemical transformation. The inventive method is different than previously known methods, teaching the utili- sation of cyclodextrins to prevent the plasticiser migration, because the better complex forming properties of the primary decomposition product of DEHT, 2 -ethylhexanol as compared to DEHT has been confirmed by NMR spectroscopy. It was also disclosed in this invention that the primary oxidation product of 2- ethylhexanol also forms inclusion complexes with the described compounds and so not only the volatility of the aldehydes is reduced, but further prevention of the oxidation is also possible. However, the complex of the final oxidation state, the carbox- ylic acid, which is considerably less volatile and practically odourless, is less stable and the constant reformation of the alcohol/cyclodextrin complex is therefore possible.

A comparison of the complexation abilities of the most probable first generation decomposition products of these aryl esters shows that the following stability order can be created on the basis of NMR spectroscopy: 2-ethylhexanoic acid << DEHT << 2 -ethylhexyl acetate 2- ethylhexanal < 2-ethylhexanol < 3-heptanone: this scale could not be foreseen according to the prior art .

The present invention exploits the higher affinity of low alkyl chain alcohols, aldehydes and ketones to unsubstituted or func- tionalised carbohydrates. The possible transesterification of the cyclodextrin ester and the casual ester formation between the acid and the parent primary decomposition product alcohol further reduces the possibility of a release of the odour compo- nents.

This invention also refers to a plastic material, containing at least one polymer and at least one plasticiser, characterised in that natural or synthetic mono-, linear, branched or cyclic oligomeric carbohydrates are added thereto.

EXAMPLES

This invention is now disclosed more in depth by reference to a few examples. The aim of such examples is to explain the invention, not to limit its scope, which is defined by the en- closed claims.

Example 1. Preparation of peracetylated cyclodextrin containing PVC composite.

Peracetylated cyclodextrin is prepared by any known meth- ods, preferably by the methods described below. Cyclodextrin hydrate (270-360 g, 0.25 mol) is suspended in 1.3-1.7 litres of acetic anhydride at -15 °C, FeCl3.6H20 (3.4 g, 0.0125 mol) is added and the mixture is immersed into an ice -bath. During the reaction, the temperature of the reaction mixture is kept below 40 °C. Upon complete dissolution of the cyclodextrin, all hydroxy groups are acetylated and the reaction mixture is poured onto ice (17 kg), then the ice is allowed to melt. The crystalline crude product is filtered and washed to neutral pH with wa- ter and dried at 60-70 °C. The obtained solid recrystallised from methanol (2.5 litres) and resulted in pure peracetylated cyclodextrin (yields: =85 %, β=80 %;γ=80 %).

Example 2. Grafting peracylated cyclodextrins to plastics .

The prepared peracetylated cyclodextrins are grafted by any known methods in various amounts to a PVC based flexible plastic, preferably using the method described below. Peracetylated cyclodextrins are dissolved in a solvent (water, alcohols,..) , sprayed onto a PVC surface and then the solvent is removed.

Example 3. Bio-sensoric experiments.

PVC composites with and without the cyclodextrin additives were tested periodically by 5 persons in blind experiments in a half year period, as summarised in the following table.

Table 1. Results of bio-sensoric experiments

Fresh 1 month 2 months 6 month β-cyclodextrin (pCD) -, 5/5* -, 5/5 5/5 -, 5/5

DEHT -, 5/5 -, 5/5 5/5 (+), 3/

TOTM -, 5/5 -, 5/5 5/5 (+), 3/

Polymer granulate with DEHT -, 5/5 + , 5/5 (+ ) , 5/5 + , 5/5

Polymer granulate with TOTM -, 5/5 + , 5/5 ( + ) , 5/5 + , 5/5

ESBO +++, 5/5 +++, 5/5 +++ , 5/5 +++, 5/

DEHT 1 week at 75 °C -, 5/5 + , 5/5 5/5 + , 5/5

TOTM 1 week at 75 °C -, 5/5 + , 5/5 + , 5/5 + , 5/5

PVC sheet prepared with DEHT +++, 3/5 ++, 5/5 ++, 5/5 +++, 5/

PVC sheet prepared by addition+, 3/5 +++, 5/5 +++ , 5/5 +++, 5/ of 5 w/w% β-cyclodextrin

PVC brick prepared by addition+, 4/5 ++, 5/5 ++, 5/5 ++, 5/5 of 5 w/w% β-cyclodextrin

dry blended powder of PVC/DEHT -, 5/5 -, 5/5 5/5 ( ( + ) ) 3 dry blended powder Of-, 5/5 -, 5/5 5/5 ((+)) 2

PVC/DEHT/ CD (5 w/w%)

dry blended powder of PVC/TOTM -, 5/5 -, 5/5 5/5 ((+)) 2 dry blended powder of-, 5/5 -, 5/5 5/5 ((+)) 2

PVC/TOTM/ βCD (5 w/w%)

dry blended powder of PVC/DEHT- , 5/5 -, 5/5 -, 5/5 ( ( + ) ) 2 based mask composition

dry blended powder of-, 5/5 -, 5/5 -, 5/5 - 5/5

PVC/DEHT/PCD (5 w/w%) based mask

compostion

Standard PVC- -DEHT sheet, thin (+) , 5/5 (+] 1 , 5/5 + , 5/5 ++, 5/!

Standard PVC- TOTM sheet, thin (+) , 5/5 (+) 1 , 5/5 + , 5/5 ++, 5/!

Thin PVC sheet prepared by addi- 5/5 5/5 ((+)), 1/5 ((+)), tion of 5 w/w% β-cyclodextrin

Standard PVC- -DEHT sheet manufac- 5/5 5/5 -, 5/5 ((+)), tured with 3 % peracetyl CD

Standard PVC- -DEHT sheet manufac- 5/5 5/5 -, 5/5 ((+)), tured with 5 % peracetyl aCD

Standard PVC- -DEHT sheet manufac- f 5/5 5/5 -, 5/5 -, 5/5 tured with 7 % peracetyl aCD

Standard PVC- -DEHT sheet manufac- 5/5 3/5 3/5 -, 3/5 tured with 3 % peracetyl CD

Standard PVC- -DEHT sheet manufac- 5/5 5/5 -, 5/5 -, 5/5 tured with 5 % peracetyl PCD

Standard PVC- -DEHT sheet manufac- 5/5 5/5 -, 5/5 -, 5/5 tured with 7 % peracetyl CD

Standard PVC- -DEHT sheet manufac- 5/5 5/5 ((+)), 2/5 ((+)), tured with 3 % peracetyl yCD

Standard PVC- -DEHT sheet manufac- 5/5 5/5 -, 5/5 ((+)), tured with 5 % peracetyl yCD

Standard PVC- -DEHT sheet manufac- 5/5 5/5 -, 5/5 -, 5/5 tured with 7 % peracetyl yCD

*: - no smell; (-) uncertain negative opinion; (+) uncertain positive opinion; + smell; number of positive [+] signs refers to the relative intensities. Numbers after the sign:

agreed/number of persons .

Example 4. GC comparison of PVC composites.

Samples analyses were performed in an "Agilent Technologies 7820A Network GC System", equipped with a FID detector, using a capillary column (Mega PS264, length 30m; i.d. 0.25 mm; film thickness 0.30 mm). GC conditions: injection split 1:23, injector temperature 250°C; detector temperature 280°C, H2 40 ml/min, air 300 ml/min, N2 make-up 25 ml/min; He carrier gas (constant flow: 1.3 ml/min). Samples were injected by HeadSpace Sampler 7697 Agilent Technologies; oven 90°C, loop 110 °C, Transfer Line 130 °C, vial equilibration 60 min, injection duration 0.2 min.

Temperature programme: 50 °C for 2 min, 10 °C/min until 150 °C, 5 °C/min until 280 °C, 280 °C for 10 min, 10 °C/min until 300°C, 300°C for 5 min. Comparison of Head Space GC-FID chromatograms are reported in fig. 1.

Example 5. Verification of the formation of molecular link be- t een small fragments of plasticiser and cyclodextrins.

N R spectra of deuterochloroform solution at ten milli-molar scale of 2 -ethylexanol , 2-ethylhexanal , 2-ethylhexanoic acid, 3- heptanone, and peracetyl β-cyclodextrin and 1:1 mixture of com- ponents/peracetylated β-cyclodextrin at identical concentration were recorded. Comparison of the spectra of the pure components and their mixtures are shown in figs. 2A-20. Estimated apparent complex stability constants of some small possible fragments are summarised in the table 2 below.

Table 2. Estimated complex stability constants

cguest A6methyl A6relative Estimated

[M] protons to apparent Kll

[ppm] DEHT [ppm] [M "1 ]

DEHT 0.009 1.000 * *

115

3-Heptanone 0.034 0.024 3.576 411

2-Ethylhexanol 0.030 0.024 4.118 474

2-Ethylhexanal 0.035 0.020 2.905

2-Ethylhexanoic 0.034 0.002 0.297

acid

* concentration of the 2-ethylhexyl moiety

** data for DEHT: Jicsinszky et al . Phys . Chem Chem . Phys . 17 17380-17390 (2015) It is anyway understood, that the invention should not be deemed limited to the particular embodiments explained above, which have the mere function as examples, but that various modification are possible, all falling under the reach of the skilled person, without departing from the scope of the inven- tion, which is defined by the appended claims.