CA1172787A - Dehydrochlorination of vinyl chloride resins - Google Patents

Abstract

Abstract Of The Disclosure Vinylchloride resins such as polyvinylchloride, copolymers of vinylchloride and vinyl acetate and copolymers of vinylchloride and vinylidene chloride are dehydrochlorinated in water at 150 to 180°C to provide a dehydrochlorinated vinylchloride resin which can be graft copolymerized with one or more copolymerizable monomers containing polymerizable ethylenically unsaturated double bonds. Grafted copolymers in which the grafting monomer is butyl acrylate and the like provide an internally plasticized vinylchloride resin.

Description

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DehydrochlorinaCion 0f Vinyl Chloride Resins The present invention relates to the dehydrochlorination o~
vinylchloride resins such as poly(vinylchloride).
Back~round 0f The Invention Preparation of graft copolymers of polytvinyl chloride) using free radical grafting techniques is ine~ficient in that only low amounts of the grafting monomers becone chemically attached as grafted polymer to the poly(vinyl chloride) .
backbcne. Compositions resulting from these grafein~ reactions contain large amounts of un~rafted polymers which are usually incompatible with poly(vinyl chloride). Consequently, the materials haNe poor physical, optical and processin~ properties.
The main reason for the grafting inefficiency is the low reactivity of the poly(vinyl chloride) towards attack by either ,` 15 inieiator or polymer free radicals.
It is known in the literaturel'2'3 that n~ch higher grafting efficiencies can be obtained by usin~ a poly(vinyl chloride) backbone that has been partially dehydrochlorinaeed.
Partially dehydrochlorinated poly(vinyl chloride) contains unsaturated sequences (polyenes) ~hich are quite susceptible to attack by free radicials.
Various technique~ have been described for prepar~ng partially dehydrochlorinaeed poly(vinyl chloride)4. Chemical methods [treatment of poly(vinyl chloride) with bases such as potassium hydroxide or ammonia] are norm~lly carried out with the poly(vinyl chloride) dissolved in a solvent such as tetrahydrofuran in order to ~et uniform dehydro-chlorinationl'3'5. Uhiform dehydrochlor;nation can also be achieved by heating a solution of poly(vinyl chloride) in a high boiling solvent such as ethyl benzoate at eemperatuses above 160C6. Solution eechniques are~very cumbersome, however, since only dilute solutions ( 5% by weight) can be used and the resultant dehydrochlorinated poly(vinyl chloride)-must be recovered from the solvent by evaporation or precipitation~

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Base catalyzed dehydrochlorination of solid poly(vinyl chloride) occurs mainly on the particle surface and there is a strong tendency towards gel formation. More uniform dehydrochlorination of solid poly~vinyl chloride) results from a pure thermal process. To obtain uniform dehydrochlorination on dry, solid resins, the resin particles must be heated and circulated with an inert gas as in a fluidized bed7. Alternatively, fluids such as ethylene glycol, paraffin oil or maleic anhydride have been used as media in which the resin particles can be circulated to provide uniform heat transfer2'8. Poly(vinyl chloride) has been dehydrochlorinated in dimethylformamide solution containing lithium chloride9. Poly(vinyl chloride) has been dehydrochlorinated and sulfonated by treatment in sulfuric acidl. The dehydrochlorinated poly(vinyl chloride), however~ must be isolated from these fluids prior to free radical grafting, and the heat transfer fluids have to be purified before being recirculated. Poly(vinyl chloride) has been treated in aq~leous caustic at 180 to 300C to obtain a high m.w. polymer composed mostly of carbon, hydrogen and oxygen with traces of nitrogen and chlorine being present 1.
The present invention attempts to a~oid the difficulties alluded to before and to provide a novel and simple process for the dehydrochlorination of a vinyl chloride resin and the product of such process.
This invention also provides graft polymers of dehydTochlorinated vinyl chloride resins.
According to the present invention, there is provided the method which comprises dehydrochlorinating a vinyl chloride resin selected from the group consisting of homopolyvinylchloride, a copolymer of vinyl chloride and vinyl acetate containing up to about 50% by weight of vinyl acetate and a copolymer of vinyl chloride and vinylidene chloride containing up to about 50%
by weight of vinylidene chloride and mixtures thereof as finely divided particles suspended in water, by heating said resin in said water at from about

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50 to 150 psi and at a temperature of from about 150 to 1~0C for from about 1 to 2 hours to remove not over about 3% by weight, or from about 1 to 2% by weight, of chlorine from said resin, said water containing dissolved therein from about 0.1 to 5 parts by weight per 100 parts by weight of said resin of a material to prevent agglomeration of said resin during dehydrochlorination and being selected from the group consisting of a solid watar soluble electrolyte and a weak base, where said electrolyte is selected from the group consisting of the lithium, sodium, pot.assium, magnesium, calcium, strontium and barium bromide, chloride and iodide salts and mixtures of the same, ammonium chloride and the sodium, potassium, lithium and magnesium acetates and where said weak base is selected from the group consisting of the lithium, sodium and potassium carbonates and phosphates and mixtures of the same, and, in said water, free radical aqueous graft suspension polymerizing on said dehydro-:
chlorinated vinyl chloride resin a monomer containing a polyermizable ethylenical-ly unsaturated double bond and being selected from the group consisting of amides, nitriles, acrylates, alkacrylates, dienes and vinyl benzenes and mixtures thereo:E, said monomer being used in the amount of from about 50 to 200 parts by weight per 100 parts by weight of said dehydrochlorinated resin.
Thus, this invention offers a method in which a suspension of vinyl chloride resin can be dehydrochlorinated in the same media (water) in which the free radical grafting can be subsequently performed. A suspension of the vinyl chloride resin in water is heated in a closed vessel from about 50 tc 120 psi at from about - 2a -~17273~

150 to 180C for fron about 1 to 2 hours. Porous vinylchloride resins are preferred, although the techniques have been applied to non-porous resins. During this heating, the vinylchloride resin becomes partially dehydrochlorinated (not over about 3%
chlorine loss by weight). From about l to 2% by weight chlorine loss is preferred for use in making the graft copolyners described herein. With higher levels of chlorine loss in this process, there is a tendency for gel ~ormation and increased color in the subsequent graft copolymers. With chlorine losses above 5% by weight, the resultant dehydrochlorinated vinylchloride resin itself tends to become crosslinked.
The graft copolymers are produced by reacting the dehydro-chlorinatecl vinylchloride resin with monomers and free radical initiato¢s in an aqueous suspension process. The grafted product is in the form of free-flawing particles which can be recovered by filtration or centrifugation. This method also offers the possibility of using the aqueous suspension for dehydro-chlorination and grafting obtained originally by polymerizing the vinylchloride resin by a suspension polymerization process. The resultant graft copolymer can thus be produced directly in the same aqueous media and vessel in which the vinyl chloride is polymerized provided there are no inhibitors, short stops or catalysts residues present which might interfere with the subsequent graft polymerization or copolymerization. This will save the steps required in isolating the vinylchloride resin. In addition, ~mlike the techniques described in the previous literature, no solvents or other organic media are required for the dehydrochlorination.
During the dehydrochlorination in water there is a tendency for the dehydrochlorinated vinylchloride resin to agglomerate, possibly due to the development of electrostatic charges. It has been found that this agglomeration preferably can be avoided by carrying out the dehydrochlcrination in a dilute electrolyte (e.g. sodium chloride, sodium iodide) solution. Free-flowing ~7~71~

partîcles of partially dehydrochlorinated vinylchloride resin, thus, can be obtained. Alternatively, it is possible to introduce weak bases (e.g. sodium carbonate, trisodium phosphate) to capture the hydrogen chloride evolved during dehydro-chlorinatic~. Also, the acid in the water may be neutralizedwith NaOH or other alkaline solutions.
I~hen monomers such as acrylates are grafted to the partially dehydrochlorinated poly(vinyl chloride), there is a significant increase in the grafting efficiency (% acrylate grafted to the vinylchloride resin) compared to compositions obtained from unmodified vinylchloride resins. The high level of grafting results in increased compatibili~y and significant improvement in the physical, optical and processing properties of the resin. If monomers with a low glass transition temperature (such as acrylates) are grafted to the partially dehydrochlorinated vinylchloride resin, internally plasticized vinylchloride resin compositions result. These compositions are useful in makin~ films and coated fabrics and can be calendered, molded or e~truded into various flexible products such as in covers for ar~ rests, seats, chairs and so forth.
Discussion Of Details And Preferred Embodiments The vinylchloride polymer or resin to be dehydrochlorinated is homopolyvinylchloride, vinylchloricle-vinyl acetate copolymer containing up to about 50/O by weight of vinyl acetate, and vinylchloride-vinylidene chloride copolymer containing up to about 50% by weight of vinylidene chloride and mixtures.of the sameO m ese polymers are made by the suspension polymerization process. Suspension polymerization is well known as shown by Schildknecht, "Vinyl and Related Polymers," 1952, John Wiley &
Sons, lnc., New York. See, also, '~odern Plastics Ehcyclopedia,"
October, 1980, Volume 57, Number 10A, McGraw-Hill Co. Inc., New York, pages 104, 10~ and 110. These suspension polyners are obtained as finely divided particles or solids. The preferred vinylchloride resin to use is poly(vinylchloride).

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Sufficient water is used during dehydrochlorination to suspend the particles of the vinyl chloride resin. Generally, there may be used a suspension of from about 15 to 50% by weight solids of the vinyl chloride resin in water, preferably about 25% solids of the vinyl chloride resin in water.
The water soluble solid electrolyte ~a substance which dissociates into two or more ions) or salt used to prevent agglomeration can be a water soluble halide salt of an alkali metal or alkaline earth metal such as a lithium, sodium, potassium, magnesium, calcium, strontium or barium bromide, chloride or iodide salt or mixture thereof. Examples of such salts are lithium chloride, lithium iodide, sodium chloride, sodium bromide, sodium iodide, potassium bromide, magnesium chloride, calcium bromide, calcium iodide, barium chloride, barium iodide, strontium chloride and strontium bromide. Sodium chloride is the preferred salt to use.
Still other water soluble electrolytes can be used such as ammonium chloride, sodium acetate, potassium acetate, lithium acetate, magnesium acetate and so forth.
The weak base ~a base that does not ionize greatly) used to prevent agglomeration can be an alkali metal carbonate or phosphate like sodium carbon-ate, trisodium phosphate, lithium carbonate, lithium phosphate, potassium carbonate, or potassium phosphate or other water soluble solid weak base or mixture thereof.
On a dry weight basis the electrolyte or weak base is used in a very minor amount of weight as compared to the vinyl chloride resin and sufficient to prevent agglomeration during dehydrochlorination of the vinyl chloride resin.
Preferably, the electrolyte or weak base is used in an amount of from about 0.1 to 5.0 parts by weight per 100 parts by weight of the vinyl chloride resin.
After dehydrochlorination of the vinyl chloride resin in water may be filtered or centrifuged to remove the water, washed and then resuspended in t- ~
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water to permit graft polymerization. Since the water ln which the vinyl chloride resin is mixed usually - 5a -.~72~7 contains not more than about 0.10 mole of acid, it may be used as the graft polymerization or copolymerization medium provided the monomers used are not affected adversely.
The technique of polymerizing or copolymerizing one or more monomers in the presence of a polymer or a substrate, "~raftin~
~echnique," is kncwn and is frequently called graft polymerization or graft copolymerization. In this connecticn, please see "Proceedings 0~ The Third Rubber Technology Gongress,"
1954, W~ Heffer & Sons, Ltd., Cambridge, pages 185-195;
"Copolymerization," High Polymers, Vol. XVIII, Ham, Interscience Publishers a division of John Wiley & Sons, New York, 1964;
"Block and Graft Polymers," Burlant and Hoffm~n, Reinhold Publishing Corporation, New York, 1960; "Block and Graft Copolymers," Ceresa, Butterworth & Co. (Publishers) Ltd., London, 1962; Ceresa, "Block and Graft Copolymerization," Vol. 1 (1973) and Vol. 2 (1976), John Wiley & Sons, Ltd., ~ew York; and '~Graft Copolymers," Polymer Reviews, Vol. 16, Battaerd and Tregear, Interscience Publishers, a division of John Wiley & Sons, New York, lg67. See, also, U.S. Patents ~s. 3,180,908 and

3,519,702. The graft copolymer may c~ltain all graft copolymer but also may be a mixture of homopolyners, copolymers as well as the graf~ itself, depending on the rate of polymerization of the monomers under the polymerization conditions and so forth.
Examples of monomers which may be graft polymerized or copolymerized with the dehydrochlorinated vinylchloride resin are those monamers containing polymerizable ethylenically unsaturated double bonds such as the amides like acrylamid~, methacrylamide and N-hydroxymethyl acrylamide; the nitriles like acrylonitrile and methacrylonitrile; the acrylates and aLkacrylates like methyl acrylate, ethyl acrylate, butyl acrylate, ethyl hexyl acrylate, octyl acrylate, hydroxy ethyl acrylate, hydroxy propyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl ethacrylate, ethyl ethacrylate, butyl ethacrylate and octyl ethacrylate; the dienes such as butadiene-1,3, chloroprene~
2,3-dimethyl butadiene-1,3, piperylene and isoprene, and the ~7278~

vinyl benzenes like styrene, alpha m~thyl styrene, p-tertiary butyl styrene, methyl vinyl toluene and para vinyl toluene and the like and mixtures of the same.
When graft copolymerizin~ a hard monomer like styrene, it is desired to include with the styrene a sufficient amount of a soft monomer like butyl acrylate or butadiene to act as a plasticizer. Also, comonomers like acrylonitrile mqy improve homogeniety and compatibility in the resulting resin. Even though both acrylonitrile and methacrylonitrile can be used in these graft copolymers, it has been found thae the latter has l~ss tendency to yellow. The parts by weight ratio of the soft monomer to the hard monomer may be from about 2:1 to 20:1.
It is particularly desirable to use mixtures of nitriles and acrylates which can form polyacrylates having a low Tg such as on the one hand acrylonitrile or methacrylonitrile and on the other hand an acrylate or methacrylate monomer which could form an acrylate polymer having a Tg (glass transition temperature) of not above about -20C. Examples of such acrylate monomers are ethyl acrylate, n-propyl acrylate, n-butyl acrylatel hexyl acrylate, octyl acrylate, 2-ethyl hexyl acrylate, decyl acrylate, methoxy ethyl acrylate, ethoxy ethyl acrylate, methoxy propyl acrylate and ethoxy propyl acrylate and the like. These monomers, thus, have the ~eneral formula CH2=CH-o~OR where R is an alkyl group of 2 to 10 carbon atoms or a -R'oR" group where R~
is an alkylene group of 2 to 3 carbon atom~ and R" is a~ alkyl group of 1 to 2 ca~bon atoms. It will be noted that poly(n-butyl acryla~e) has a Tg of -55C. and poly(2-ethyl hexyl acrylate) has a Tg of -77C. Also, there may be used as the a ylate monomer, mononers having the formula ~ C-C(C ~)COOR " ' where R " ' is an alkyl group of 8 to 18 carbon atoms such as n-octyl methacrylate, n-dodecyl methacrylate, hexadecyl methacrylate and n-octadecyl ~ethacrylate and the like. Poly~nqoctyl methacrylate) has a Tg of -20C. and poly~n-octadecyl methacrylate) has a Tg of -100C. Mixtures of these acrylate monomers may be used. However, the higher molecular weight acrylate and methacrylate monomers are less compatible (phase ~7~7~

separation~ with polyvinyl chlcride. Thus, the higher molecular weight acrylate and methacrylate monomers should be used in mixtures, in am~unts up to 25% by wei~ht of the mixture, with a lower molecular weight acrylate like ethyl, propyl and/or butyl acrylate. Of these acrylate mono~ers it is preferred to use n-butyl acrylate.
Overall in the graft polymerization process there can be used from about 50 to 200 parts by weight of the grafting monomer or monomer mixture per 100 parts by weight of the dehydrochlorinated vinylchloride resin.
Graft polynerization should be conducted in a closed reactor, such as a pressure reactor, fitted with a stirrer or other agitating means, heating and cooling means, with means to flush with or pump in an inert gas such as nitrogen, helium, argon, neon and the like in order to polymerize preferably under controlled, inert or non-reactive conditions, with means to charge the resin (if previously separated), monomers, water, initiators and so ~orth, venting means, and with means to recover the graft polymer and so forth. The reactor should be cleaned or Elushed out between polymerization ruls to remove traces of initiators, modifier, colloids, residues and the like which might interfere with subsequent polymerizatiLons. There should be sufficient agitation or stirring of the polymerization media to ensure thorough mixing, diffusion, ca~tact and so forth. All of the polynerizaticn ingredients may be charged to the reactor at the sa~e time, intermittently, increm~ntally or continuously.
Also, the ingredients may be added separately or in a nuxture.
Temperatures used during ~raft polymerization should be sufficient to effect polymerization by activation of the initiator and double bonds of the mKnomers. They should not be too high to cause a runraway reaction and not too low to retard polymerization. In general, the temperature m~y be from about 2 to ~0C. I~ even lower temperatures are used, it may be desirable to add an-inert anti-freeze ~aterial to the '' ""' ' .:
;

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g polymerization media. Water is used in an amount sufficient to obtain the desired degree of suspension or dispersion, cooling, mixing, solids content and so forth.
Graft polymerization of the monomers is efEected by free-radical initiators Gfree-radical formers or free-radical fornun~ systems, catalysts) such as ammonium, potassium~or sodium persulfate, ~ 2 and the like in an amount sufficient for polymerization of the monamers. Other free-radical initiators can b~ used which decompose or become active at the temperature used during polymerization. Examples of some other free-radical initiators are cumene hydroperoxide, dibenzoyl peroxide, diacetyl peroxide, didecanoyl peroxide, di-t-butyl peroxide, dilauroyl peroxide (preferred), bis (plmethoxy benzoyl) peroxide, t-butyl peroxy pivalate, dicumyl peroxide, isopropyl percarbonate, di-sec-butyl peroxydicarbonate, azobisdimethyl-valeronitrile, 2,2'-azobisisobutyTonitrile, 2,2'-azobis-2-methylbutyronitrile and 2,2'-azobis Gmethylisobutyrate) and the like and mixtures of the same. 0nly minor am3unts of initiators are necessary to effect polymerization.
Protective colloids having little surface activity are desirably used in the graft suspension polymerization process to provide finely divided particles suspended in the aqueous medium. Examples of useful protective colloids are copolymers of from 30 to 50% vinyl acetate, balance 1-vinyl-2-pyrrolidone.
Other polymers can be used as a colloid such as those obtained by copolymerizing a pyrrolidone, such as l-vinyl-3-pyrrolidone, or vinyl piperidone, with a copolymerizable mKnomer`like vinyl acetate, acrylic acid, methacrylic acid, butyl acrylate, ethyl acrylate, methyl acrylate, ethyl vinyl ketone, allyl acetone, methyl (5-hexene-2-one) vinyl ether, vinyl isobutyl ether, allyl alcohol, 3-buten-1-ol, and the like and mixtures thereof. Still other protective colloids may be used, for example, gelatin, polyacrylamide, hydroxy ethyl cellulose, hydroxy propyl methyl cellulose (preferred), carboxy methyl cellulose,~methyl cellulose, gun arabic, gum tra~acanth, lcw molecular weight polyvinyl alcohols etc. These protective colloids are used in ., ~

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amounts of frorn about 0.01 to 4.0% by weight, and preferably from about 0.1 to 2% by weight, based on the weight of the graft polymer obtained.
Other materials which may be used during the graft polymerization are chelating or sequestering agents, chain transfer agents or modifiers such as tertiary alkyl merc ptans to prevent or reduce gel, stabilizers, antioxidants and shortstops ~to stop the polymerization at the desired conversion and prevent further polymerization during stripping, work-up and so forth).
Swelling agents for the dehydrochlorinated resin, also, may be used to facilitate ~he graft polymerization or copolymerization processO
The following examples will serve to illustra~e the present invention with more partlcularity to those skilled in the art.
In these examples the parts are parts by weight unless otherwise noted.
Example 1 PVC I (3,000 gr~ms) and ethylene ~lycol (12 liters) were charged to a 5-gallon stainless steel reactor. The reactor was equipped with a stirrer, electrical strip heaters and a bottorn take-off valve. The reactor with its contents were heated to 160C over a period of 50 minutes. The wall temperature of the reactor was maintained at 165C (which kept the ethylene glycol/PVC I slurry at 160CC) for 2 hours. Ihe reactor and its contents were cooled to ambient temperatule and the ethylene glycol/dehydrochlorinated PVC I slurry was discharged through the bottom valve. Ihe dehydrochlorinated PVC I was recovered by filtration and was washed with water and dried. The dried resin consisted of orange-colored particles and had 55.78% chlorine (original PVC I has 56.73% chlorine). The resin was soluble in tetrahydrofuran and had a series of absorbances in the visible spectrum from 250-600 nm, characteristic of polyene sequences of different len~ths ~approximately C2 ~o C12).
Exanpl~ 2 m e method described in Exanple 1 was repeated exactly, except that the ethylene glycol was replaced with water (14 .

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liters~. Ihe dehydrochlorinated P~C I could not be discharged through the bottom valve but was caked in the upper level of the reactor. This cake was removed, broken up into fine particles, washed with water and dried. The resultant orange-colored resin had 55~7~/O chlorine and was soluble in tetrahydrofuran. A series of abscrbances was found in the visible spectrum from 250-600 nm, characteristic of polyene sequences of different lengths.
Example 3 The method described in Example 2 was repeated exactly, except that 75 grams of sodium chloride were added to the water/PVC I mixture. The resultant dehydrochlorinated PVC I
flcwed freely through the bottom valve of the reactor. Ihe res;n was recovered by filtration, ~ashed with water and dried. The resultant dehydrochlorinated PVC I was orange-colored, soluble in tetrahydrofuran and had 56.24% chlorine. The visible spectrum showed a series of absorbances from 250-600 nm, characteristic of polyene sequences of various lengths.
Exame~e 4 The method of Example 3 was repeated exactly, except that the temperature of the waterlPVC I slurry was kept at 150C. The resultant dehydrochlorinated PVC I discharged easily from the bottom valve of the reactor. The resin was orange-colored, soluble in tetrahydrofuran and had 56.46% chlorine.
Example 5 Ihe method of Example 4 was repeated exactly, excep~ that the temperature of the waterlPVC I slurry was kept at 140C. The dehydrochlorinated PVC I resin that was recovered consisted of small orange particles which were soluble in tetrahydrofuran and had 56.15% chlorine.
Exa~
The method of Example 4 was repeated exactly, except that the sodium chloride was replaced with 75 grams of sodium iodide.
The dehydrochlorinated P~C I that resulted discharged easily from the bottom valve of the reactor. It was orange-colored, soluble in tetrahydrofuran and had 55.63% chlorine.

1~727~'7 Example 7 The method of Example 2 was repeated exactly, except that the reactor contents were heated at 155C and 10.5 grams of sodium carbonate were added to the slurry. The resultant dehydrochlorinated PVC I discharged easily from the bo~tom valve of the reactor. It was dark yellow-colored, soluble in tetrahydrofuran and had 55.52% chlorine.
Example 8 The method of Example 3 was repeated exactly, except that the poly(vinyl chloride) used was PVC II instead of PVC I. The dehydrochlorinated PVC II discharged easily from the bottom valve of the reactor. It was orange-colQred, soluble in tetrahydrofuran and had 56~4~/o chlorine.
Example 9 The method of Example 3 was repeated exactly, except that PVC III was used instead of PVC I. The dehydrochlorinated PVC III
discharged easily from the reactor. It was orange-colored, soluble in tetrahydrofuran and had 56.()9% chlorine.
Example 10 Example 3 was repeated exactly, except that PVC IV was used instead of PVC I. m e dehydrochlorinal:ed PVC IV discharged easily from the reactor. It was pale yellow, soluble in tetrahydrofuran and had 56.61% chlorine.
Example 11 25~ A mixture of n-butyl~acrylate (S0 grams), methacrylonitrile (5.25 grams) and "Alperox'~rF (2 grans) (dilauroyl peroxide, 98C/
Pe~nwalt, Lucidol Chem. Div.) was prepared. ~his mixture was added to a quart polymerization bottle ~hich contained PVC I (50 grams), water ~400 grams3 and '~ethocel J 75 HS (0.25 gram) ohydroxy propylmethylcellulose, Dow Chemical Co.). The bottle was capped and placed in a 6~C polynerization bath. The bottle and its contents were rotated in the bath at 60C for 18 hours.
The bottle was r~moved and its contents were poured onto a filter. The filtered product was washed with water and dried. A
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99% yield of product was obtained which consisted of small white particles. Five grams of this product were placed in a Soxhlet extraction apparatus and extracted for 36 hours with cyclohexane. The cyclohexane dissolved 1.8 grams of ungrafted, rubbery product which was shown by infrared spectroscopy to consist of a copolymer of butyl acrylate and methacrylonitrile.
On this basis, a grafting efficiency (% of the acrylate reacted that became grafted to the PVC I) of 31% was calculated.
Example 12 The method of Example ll was repeated exactly, except that the reaction product of Example l was used instead of PVC I.
During the grafting reaction, the orange-colored dehydrochlorinated poly(vinyl chloride) was transformed into a product which consisted of small while particles. The grafting efficiency, as determined by cyclohexane extraction, was 63%.
Examp~
The method of Example 11 was repeated exactly, except that the reaction product of Example 3 was used. A product consisting of small while particles was obtained. The grafting efficiency was determined to be 7~/O~
Example 14 Using the same generalized procedure described in Example 11, graft copolymers were made from all of the dehydroch~orinated poly(vinyl chloride) samples obtained in Examples l-10. The 25 ~ grafted products were mixed wi,th typical poly(vinyl chloride) stabilizers using a Brabender~Plasti-Corder at 150C.
C~mpression- lded tensile sheets were prepared at 150C from the various compositions. The physical properties of each composition are listed in the following table.
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'rable Poly(vinyl chloride) Used 100% Tensile Graves for Graftin~ Mbdulus ~ Elon&ation Tear Shore "A"
MPa MPa % kN/m PVC I
(E~ample 11) 5.79 6.69 240 35.7 90 Example 1 7.52 10.5 235 49.2 91 EKample 2 7.26 10.0 235 48.6 8g Exanple 3 6.93 9.9 235 48.6 90 Example 4 8.53 11.3 260 51.1 96 Example 5 7.65 9.5 235 44.5 94 EXample 6 8.23 11.5 255 52.5 96 Exanple 7 7.39 10.1 230 45.2 92 Example 8 7.16 9.9 300 53.0 94 E~ample 9 8.97 11.9 230 52.5 96 F~mple 10 8.16 8.63 140 43.0 95 Notes:
1. U.S. Patent ND. 2,908,662, W. Rees.
20 2. U.S. Patent Nb. 3,576,914, J. Dbnat.
3. 0stensson and Flodin, JO Macramol. Sci.-Chem., A12(2), 249-260 (1978).

4. D. Braun, Pure and Applied Chemistry, Vol. 26, #2, 173 (1971).
25 5. A. Wirsen and P. Flodin, J. Appl. Poly. Sci. 22, 3039 (1978).
6. I. K. Varma and K. K. Sharma, Oie Angewandte Makromolekulare Chemie 78, 181 (1979).
7. Netherlands Patent Specification 7214020, Dow Chemical Cn.
30 8, U.S. Patent Nb. 3,896,091, H. J. Fabris, H. Ublzmann and W. J. van Essen.
9. J. P. Roth, P. Rempp and J. 8arrod, Jour. o~ Polymer Science, Part C, Nb. 4, L~i7 (1963).
10. Z. Wolkober, Jour. of Poly,ner Science, Vol. 58, 1311 (1962).
11. U.S. Patent Nb. 3,826,789~ C. Yokokawa.

` 1;~72~7 PVC I Homopolyvinylchloride, inherent viscosity of 0077, ASIM-D1755, porous.
PVC II Homopolyvinylchloride, inherent viscosity of 0.$7, ASTM-D1755, non-porous.
PVC III Homopolyvinylchloride, inherent viscosity of l.Q3, ASIM-D175S, porous.
PVC IV HomDpolyvinylchloride, inherent viscosity of 0.99, ASTM-D1755, non-porous.
PVC I, II, III and IV were all finely divided, free-radical, aqueous suspension polymerized vinylchloride polymers.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. The method which comprises dehydrochlorinating a vinyl chloride resin selected from the group consisting of homopolyvinylchloride, a copolymer of vinyl chloride and vinyl acetate containing up to about 50% by weight of vinyl acetate and a copolymer of vinyl chloride and vinylidene chloride containing up to about 50% by weight of vinylidene chloride and mixtures thereof as finely divided particles suspended in water, by heating said resin in said water at from about 50 to 150 psi and at a temperature of from about 150 to 180°C for from about 1 to 2 hours to remove not over about 3% by weight, or from about 1 to 2% by weight, of chlorine from said resin, said water containing dissolved therein from about 0.1 to 5 parts by weight per 100 parts by weight of said resin of a material to prevent agglomeration of said resin during dehydro-chlorination and being selected from the group consisting of a solid water soluble electrolyte and a weak base, where said electrolyte is selected from the group consisting of the lithium, sodium, potassium, magnesium, calcium, strontium and barium bromide, chloride and ioclide salts and mixtures of the same, ammonium chloride and the sodium, potassium, lithium and magnesium acetates and where said weak base is selected from the group consisting of the lithium, sodium and potassium carbonates and phosphates and mixtures of the same, and, in said water, free radical aqueous graft suspension polymerizing on said dehydrochlorinated vinyl chloride resin a monomer containing a poly-merizable ethylenically unsaturated double bond and being selected from the group consisting of amides, nitriles, acrylates, alkacrylates, dienes and vinyl benzenes and mixtures thereof, said monomer being used in the amount of from about 50 to 200 parts by weight per 100 parts by weight of said dehydrochlorinated resin. 16

2. The method according to claim 1 where said monomer is a mixture of (A) an acrylate and/or an alkacrylate which can form a polymer having a Tg of not above about -20°C and (B) a nitrile, the parts by weight ratio of (A) to (B) being from about 2:1 to 20:1.

3. The method according to claim 1 where said resin is a porous or non-porous homopolyvinylchloride.

4. The method according to claim 2 where said resin is a porous or non-porous homopolyvinylchloride.

5. The method according to claim 1 where a protective colloid is present in said free radical aqueous graft suspension polymerization step.

6. The method according to claim 2 where a protective colloid is present in said free radical aqueous graft suspension polymerization step.

7. The method according to claim 3 where a protective colloid is present in said free radical aqueous graft suspension polymerization step.

8. The method according to claim 4 where a protective colloid is present in said free radical aqueous graft suspension polymerization step.