IL46190A - Process for the production of transparent impact-resistant polymerisates of vinyl chloride - Google Patents

Abstract

In an emulsion polymerisation process for the preparation of weathering-resistant polymers of vinyl chloride, the polymerisation of the monomers, comprising from 80 to 100% by weight of vinyl chloride, is carried out in the presence of a prepolymer dispersed in the aqueous phase. With this prepolymer as additive, a polymer having improved transparency and simultaneously high impact strength is obtained. The prepolymer is a copolymer of monounsaturated acrylates with a small amount of polyfunctional monomer; the polyfunctional monomer contains at least two non-conjugated ethylenic double bonds, of which at least one is of the allyl type. [FR2291219A1]

Description

D'snps? oa*nv »n»ni a »a»n o*ia» is i x»» T» nn Prooess for the production of transparent impact-resistant polymerisates of vinyl chloride Lonza Ltd. mers of vinyl chloride by the polymerisation of vinyl chloride, if desired, together with aqueous dispersion by the the presence of copolymers of esters of acrylic acid.

It is known (Belgian Patent No. 770,011) that it is possible to manufacture polymers of vinyl chloride by the polymerisation of vinyl chloride by the emulsion polymerisation process in the presence of 2 to 10% by weight of a polymer of 2-ethylhexylacrylate. The products obtained in this way, as compared with those produced using earlier technical knowledge, exhibit improved impact strength and improved transparency.

They are suitable for the production of translucent products, but, however, they exhibit a cloudiness (as defined below), which is too marked to make it possible to permit their use for applications requiring transparent qualities. However, if better transparency should be required, the concentration of the pre-polymer from 2-ethylhexylacrylate can be decreased or the diameter of the particles of the poly-2-ethylhexylacrylate can be decreased. However, both of these measures reduce the impact strength.

In accordance with another known process, a copolymer comprising 65 to 95% by weight acrylic ester and 35 to 5% by weight of CG-methylstyrene can be used as the pre-polymer in the emulsion polymerisation of vinyl chloride. This has the effect is that the transparency is improved; but high resistance to impacti achieved only when large amounts of acrylate copolymer is used.

It has now been found that weather-resistant polymers of vinyl chloride with improved transparency and, at the same the pre-polymer used comprises a copolymer of acrylic esters wi et vinyl chloride or mixtures of monomers containing at least 8055 by weight of vinyl chloride are polymerised in the presence of a dispersion of at least one copolymer of 90 to 99.7% by weight of at least one ester of acrylic acid with 3 to 16 C-atoms in the ester group and 0.3 to 10% by weight of a poly-functional monomer with at least two non-conjugated ethylenic double bonds, at least one of which is an allyl group, whereby the copolymer possesses a mean particle diameter of 30 to 150 nni, determined by titration as soap, preferably 40 to 120 nm, and is used in amounts such that the final polymer contains -4 to 20% by weight of acrylic acid ester components.

Preferably, copolymers are added which comprise 95 to 99.5% by weight at least of an acrylic acid ester with 3 to 16 C atoms, preferably 4 to 8 C atoms, in the ester group and 0.5 to 5% by weight of a poly-functional monomer with at least 2 non-conjugated ethylenic double bonds, at least one of which is an allyl type. In this case, the acrylic ester component in the copolymer may comprise only one acrylic ester or may coitprise a number of different acrylic esters. For example, such acrylic esters may comprise propyl-, isopropyl-, butyl-, isobutyl-, hexyl-, 2-ethylhexyl-, lauryl-, myristylacrylate.

Preferably, copolymers, which contain at least 90% by weight of 2-ethylhexyl acrylate, are employed.

As poly-functional monomers with at least one allyl double bond, for example, the following compounds come into mono- or poly-carboxylic acids such as allylacrylate, allylmethacrylate, allylcrotonate, allylcinna ate, acrylate, methallylmethacrylate, monoallylmaleate, fumarate; di-, tri- and tetra-allyl- and methallyl -esters of saturated or unsaturated polycarboxylic acids, as well as of cyanuric acid or phosphoric acid, such as diallyl- and dimethallyloxalate, diallylglutarate, diallyl adipate, diallyl-phthalate, diallyl terephthalate , tetraallyl pyromellitate, diallyl maleate, dimethallyl maleate, diallyl fumarate, diallyl isocyanurate, triallyl cyanurate, triallyl phosphate; di- or poly-al yl ethers of polyvalent alcohols and polyallyl acetals, such as trimethylolpropane diallyl ether, trimethylolpropane dial lylether -mono-methacrylate, tetraallyl-oxyethane.

The poly-functional allyl monomers can be added · initially, or added in stages or continually during the course of the reaction, for example, as a mixture with the acrylic ester, or the acrylic esters. In a further method for the realisation of the invention, the poly-functional allyl monomers can be added only after the acrylic ester has reacted to an amount of at least 60%, preferably 80%.

The amount of the copolymers of acrylic esters which are used in the process is so determined that the acrylic ester units are present in the final product to an amount of 4 to 20% preferably 5 to 10% by weight. This means that the amount lies within the limits in accordance with the invention, depending on the nature of the acrylic ester, the polymerisation temperature, the particle size and the desired properties of the final product. Over the whole of the limits within the scope of the invention, the cloudiness remains slight; softening temperature and a high rigidity. On increasing the content of acrylic ester copolymer the resistance increases in general, and the rigidity decreases. The rigidity can be easily selected by the expert for a special purpose as the most suitable combination of properties on the basis of a few experiments.

The copolymer of the acrylic esters made by the process in accordance with the invention is used in the form of aqueous dispersions. These can be made by emulsion pol merisation of the raw monomers in the presence of water-soluble initiators and of emulsifying agents. The mean particle diameters of the copolymers formed are determined by the conditions employed in the emulsion polymerisation, as is well known.

Dispersions of copolymers of different mean particle sizes can be produced, for example, by variation of the amounts of monomers used. Emulsifiers which can be added mainly comprise salts of fatty acids with a chain length of 12 to 18 C-atoms. Preferably, the alkali or ammonium salts of lauric acid, myristic acid, oleic acid, fatty acids from coconut oil, palmitic acid, stearic acid, etc. can be used. These emulsifiers are suitably used in- amounts of 2 to 12% by weight, based on the amount of acrylic monomers employed.

A further possibility for the influencing of the diameter of the particle of the copolymers lies in the method by which the monomer and/or the e ulsifier is added. For example, it is well known that coarser dispersions are obtained, if only a portion of the whole amount of emulsifier is added and the remainder added during the course of the reaction. with coarse average particle d ameters, the copo ymer sat on can be carried out in the presence of a previously formed l jtex of an acrylic ester homo- or copolymer. In this case, the conditions for the polymerisation are so selected that only the existing particles of the polymer increase in size without the formation of new particles.

The mean particle diameter can basically be determined * using different methods, such as by scattering of light, using the disc-type centrifuge or by electron microscopy. In the last case, there is the danger that the particles of polymer may be so strongly altered while taking the samples or during the measurements owing to their low softening temperature by agglomeration or melting, that it is no longer possible to make any reliable measurements.

Owing to its simplicity the titration with surface active agents has been found especially suitable. This method is well known and has been used by many authors (Houben-Weyl XIV/1, page 369). It is based on the determination of the specific surface of the particles of the dispersion being investigated. If the mean particle diameter in nm is designated by "d«», and '»Ε" the amount of emulsifier in grams, which is required to coat 1 gram of the polymer with a monomolecular layer of emulsifier, and assuming the value 1.00 for the density of the polyacrylate or the copolymer of the acrylic ester, then, according to Jacobi, (Angewandte Chemie, 64, 539-543 (1952)), we have the expression: d - 9g·4— for the titration with Mersolat K 30.

The polymerisation of the vinyl chloride, if desired As copolymerisable monomers which can be used in addition to vinyl chloride, (C-olefins are of particular interest, for example, ethylene, propylene, 1-butylene, unsaturated esters^^ carboxylic acids, especially vinyl esters such as vinyl acetate vinyl propionate, vinyl laurate, vinyl stearate, etc., as well as esters of acrylic acids with 1 to 18 C-atoms in the alkyl group, or aleic or fumaric acid di -esters with 1 to 12 C-atoms in the alkyl group, unsaturated ethers, such as alkylvinyl ethers, for example, methyl-, ethyl-, butyl-, isobutyl^, lauryl cetyl-, stearylvinyl ethers, or isopropenylmethyl- or isopropenylethyl ether come into consideration. The ct-olefins and the unsaturated carboxylic acid esters are preferably added in amounts of 3 to 20% by weight, the unsaturated ethers in amounts of 1 to 15% by weight.

The emulsifiers used comprise mainly anion-active emulsifiers such as, for example, salts of carboxylic acids, alkyl sulphates, alkyl- or alkylarylsulphonates. Preferably, salts of fatty acids with a chain length of 12 to 18 C-atoms, mainly the alkali or ammonium salts of lauric acid, myristic acid, oleic acid, fatty acids of coconut oil, palmitic acid, stearic acid, etc. are used. These emulsifiers are preferably used in amounts of 0.05 to 1%, in relation to the monomers.

The catalysts added comprise water-soluble compounds which produce free radicals, such as peroxides, persulphates, azo-compounds , Redox compounds. Advantageously, the amounts are from 0.05 to 0.5% by weight, in relation to the weight of the monomer.

The polymerisat on can be carried out in the presence unsaturated halogenated hydrocarbons are use as t e po ymerisation regulators. The amount of regulator to be used ^ depends on its type and the K-value which has to be ad ust^^ For example, dodecylmercaptan is added in amounts of 0.01 to 0.2% by weight, in relation to the vinyl chloride. Trichlor-ethylene, 1,2-dichlorethylene or bromoforra are used in amounts of 0.1 to 5%. Preferably, the K-value of the vinyl chloride polymer should lie between about 60 to 75.

The polymerisation is carried out in such a manner that a pressure vessel is used, which permits agitation, for exar-ple, in a pressure vessel fitted with an agitator, to which the aqueous dispersion of the copolymer of the acrylic ester together with the catalyst, emulsifier and, if desired, the regulator is added, and the monomeric vinyl chloride, if desired, together with other monomers, is supplied and the polymerisation carried out at the prescribed reaction temperature.

The process of the invention can be carried out in such a manner that the operating pressure amounts to 65 to 9955, preferably 75 to 99%, of the saturation pressure of the vinyl chloride or of the mixture of monomers at the corresponding polymerisation temperature. In this case, the monomeric vir.yl chloride is partly dissolved in the aqueous phase, partly absorbed in the already formed polymer and the other part in the gaseous state; however, it is never present in the reactor i the liquid state.

The operating pressure can be maintained by continuo-s or approximately continuous addition of vinyl chloride, depending on the extent to which it is being used up in the polymerisation.

This subsequent supply of vinyl chloride can be effected reactor is connected with the gas space in a supply vessel, in which monomeric vinyl chloride, if desired of a non-volatile polymerisation inhibitor, such a temperature that the pressure resulting is just sufficient to balance the prescribed operating pressure in the reactor space. It is also possible to pump in the vinyl chloride continuously in liquid form; in one preferred method of realisation of the process of the invention, liquid vinyl chloride is supplied in such small amounts that the pressure in the reactor remains approximately constant, that is, in practice, it varies by less than 0.2 at from the prescribed value. As a result of the fact that the pressure in the reactor is lower, the liquid vinyl chloride added is vaporised immediately it arrives in the reactor, so that no vinyl chloride in the liquid form can reach the centres where polymerisation is taking place.

The monomers copolymerisable with the vinyl chloride can be added either as a mixture with the vinyl chloride or separately. In the latter case, they can be added all at once or in stages, and the remainder continually or in stages during the course of the polymerisation.

After the polymerisation is completed, the polymer is treated by known methods, for example, by coagulation by addition of electrolytes, separation of the polymerisation medium by centrifuging , washing and drying in a rotary drier, or by spray drying or by spraying on a roller drier.

The polyvinylchloride material obtained in accordance with the invention exhibits throughout a higher impact strength and/or a better transparency than the corresponding product polymers of acrylic esters or of acrylic esters and CC-methyl-styrene.

This may be seen from the curves in Figures 1 and 2. 2 Figure 1 shows the impact strength in kpcm/cm as a function of the opacity of a moulded plate 1 mm thick plotted as %. The curve 1 corresponds to vinyl chloride polymers produced in the presence of 3 to 10% by weight of poly-2-ethylhexylacrylate with diameters particle kimonoi-€x>s varying between about 25 mm and about 140 mm. Curve II represents polyvinylchloride produced in the presence of acrylic ester copolymers of one or a number of acrylic esters and oc-methylstyrene with mean particle dimensions of about 25 mm to about 140 mm. The polyvinylchlorides produced in accordance with the process of the invention are shown in Curve III. In comparison with the products of Curves I and II, however, they exhibit either for the same impact strength (along a horizontal line) an opacity less by about 50%, or for the same opacity (along a vertical line) impact strengths which about represent abe«* values which are/doubled.

Figure 2 shows the impact strength of moulded plates 1 mm in thickness in kpcm/cm as a function of the percentage of polyacrylic ester contained in the final product. Curve II corresponds to the vinylchloride polymers produced in the presence of polymers of 2-ethylhexylacrylate or of copolymers of acrylic esters and fl-methylstyrene. The vinyl chloride polymers obtained in accordance with the process of the invention are located on the Curve III. For the same content of polyacrylic ester over the whole range, they exhibit superior impact strength. Since the rigidity depends primarily on the of the invention offer the possibility of producing a higher impact strength for the same rigidity or of producing a rigidity for the same impact strength. Further, in the materials made from products produced in accordance with the invention, the well known effect of "white fracture" does not occur. However, if a plate made from a vinyl chloride polyner produced by the usual* process in the presence of an acrylic ester polymer is subjected to a mechanical stress such as bending or drawing, permanent damage is produced at the stressed locations, which are made obvious as white spots. Plates from the material made in accordance with the invention can be subjected, on the other hand, for example, to being bent backwards through 180°, without any indication of white fracture.

If, in place of the poly-functional monomers with at least two non-conjugated ethylenic double bonds, at least one of which is an allyl group, such poly- unctional monomers, which do not possess any double bond of the allyl type, such as, for example, ethyleneglycoldimethylacrylate or 1,3-butyleneglycoldimethacrylate, are added, then the desired effect achieved by the process in accordance with the invention regarding impact strength, transparency and white fracture, is no longer achieved. Owing to their exceptional resistance to impact, transparency and resistance to weather, the polymers in accordance with the invention can be used in the production cf transparent or translucent products, such as sheets, tubes, profiles, and the like, by extrusion, injection moulding, calendering, and the like, and supply valuable materials for building. 1. anu ac ure o e cry c s e op e - Salt-free water, lauric acid (LS), sodium hydroxide and potassium persulphate (KPS) are supplied to a.12 litre sta steel reactor with agitator, in the amounts given in Table 1, and the whole heated while stirring to the polymerisation temperature of 70°C. After repeated evacuation and addition of nitrogen under pressure in order to clean the agitator, the whole was finally raised to 2 atm. nitrogen. After the poly-merisation temperature was reached, 100 grams of monomer or mixture of monomers were pumped in over 2 minutes. After 10 minutes the remainder of the monomer was pumped in over a period of 2 hours. After a total period for reaction of 4 hours the pressure was released and the reactor cooled. The mean particle diameter was determined by titration against surface active agents using Emulgator 30 (Bayer). The formulae for the manufacture of the pre-dispersions A to F and the pre-dispersions for comparison and their compositions are given in Table 1. 2. Manufacture of Vinylchloride Polymers Salt -free water, lauric acid, sodium hydroxide and potassium persulphate are added in amounts given in Table 2, to a 12 litre autoclave fitted with an agitator, of stainless steel, and heated to the polymerisation temperature of 59°C. Durinc the heating period, the dispersion of the acrylic ester polyasr (pre-dispersion) was added (in amounts according to Table 2). After this, the autoclave was evacuated and cleaned by repeated addition of vinyl chloride under pressure and releasing the pressure. After the polymerisation temperature Was reached, the specified amount of vinyl chloride was introduced under press-re. up to 4 at, the pressure released and then cooled. The lytes. Plates 1 mm and 4 mm thick were prepared by working on rollers mixtures of 60.5 parts by weight of vinyl chloride polymer, 1 part by weight of lubricant and 1 part by weight of an organo-t n-sulphur stabiliser for 10 minutes at 180°C, using a set of mixing rollers and presses at 180°C. The impact strength of small standard test bars was measured in accordance with DIN 53453, the Vicat softening point in accordance with DIN 53460. The opacity was measured with the aid of the "Haze" meter made by the firm Evans Electroselenium Ltd. in Halstead (England) in accordance with ASTM D 1003-61. The "haze" or opacity is defined as the ratio between light Td scattered by the sample on passing through and the total incident light Tt.

The figure is given as percentage: Opacity = Td . 100 (%) Tt In order to test the processibility, a mixture comprising 57 parts by weight of vinyl chloride polymer, 2.3 parts by weight of barium-cadmium-stabiliser and 0.7 parts by weight of lubricant were kneaded in a test kneader Type 50 of a Plasto-graph Type PI 3 S from the firm Brabender in Duisburg (Germany) at 180°C and 40 rev./min. The lowest torsional moment was taken as the measure of the processibility in kpm, reached after completed gelation was achieved. The results obtained are presented in Table 2. 3. Test No. 3 of Example 2 was repeated, however, using pre-dispersions of different particle sizes and/or lower content of allylmethacrylate. The polymerisation formulae and the 4. Tests No. 3 and 9 in accordance with the invention repeated, however, using a polymerisation temperature of or 66°C, in place of 59°C, or with the addition of about weight (in relation to vinyl chloride) of trichlorethylene. The conditions for the polymerisat on and the results are given in Table 4.

Table 1 Pre- Water LS N di spersion grams 1 A 5925 30 15 5 1000 AMA 25 70 B 5625 30 15 5 1300 AMA 30 70 C 5940 24 11 5 1000 AMA 25 70 D 5940 20 10 5 l OO AMA 25 70 E 5940 29 14,5 5 1000 AMA 10 70 F 5950 24 11 5 1000 AMA 10 70 H 5950 30 15 5 1000 70 J 5650 30 15 5 1000 300 70 K 5925 28 14 5 1000 AGDM 25 70 Ethyleneglycol dimethacrylate Allyl methacrylate 2-ethy hexyl acrylate Potassium persulphate Laurie acid nm g 01 B 65 430 5590 11 60 2 1920 59 02 B 65 560 5480 10 60 2 1900 59 03 B 65 700 53R0 9 50 2 1870 59 04 B 65 * 910 . 5210 8 45 2 1830 59 05 B 65 1190 5000 7 40 2 1780 59 KPS = Potassium persulphate LS = Laurie acid Test Content Opacity in % Brabender Impact Vicat No. in % of torsional strength EHA AMA 1mm plate 4mm plate moment °C mkp kpcm/cm^ 01 4,9 0,11 9 30 2,45 8,5 76 02 5,9 0,14 9 26 2,25 34,0 76 03 7,1 0,16 13 38 2,4 51,5 77 04 9,3 0,21 12 31 2,4 52,0 76 05 12,5 0,29 19 45 2,5 52, 76 AMA = Allyl methacrylate EHA = 2-ethylhexyl acrylate Test Pre-dispersion Water LS NaOH KPS VC Temp. No. IN No. Particle diameter 9 0 ml g 9 n 0 06 A 55 910 5230 8 45 2 1870 59 03 B 65 700 5380 9 50 2 1870 59 07 C 117 910 5210 8,8 45 2 1870 59 08 D 144 910 521.0 8 45 2 1870 59 09 E 61 910 5210 8 45 2 1870 5 10 F. 112 910 5210 8,8 45 · 2 1870 59 KPS = Potassium persulphate LS = Laurie acid Test Content Opacity in % Brar Impact Vicat No. in % of bender strength n EHA A A tors- prxate 4 mm p1iate lona,l ,kpem/.cm~' moment mkp 06 7,9 0,20 8 24 2,3 38,7 76 03 7,1 0,16 13 t 38 2,4 51,5 77 07 7,8 0,20 65 96 2,5 47,2 77 08 6,6 0,17 94 97 2,4 30,8 76 09 7,3 0,07 11 38 2,35 34,4 76 10 7,5 0,08 71 99 2,4 45,3 77 AMA = Allyl methacrylate EHA = 2-ethylhexyl acrylate Test Pre-dispersion Water LS NaOH KPS VC Tri. Temp. No. IN No. Particle diameter g g ml g g g °c nro 9 03 B 65 700 5380 9 50 2 1870 59 11 B 65 700 5380 9 50 2 1870 18 59 12 E 61 910 5210 8 45 2 1870 52 09 E 61 910 5210 8 45 2 1870 59 13 E 61 910 5210 8 45 2 1870 66 KPS = Potassium persulphate LS = Laurie acid Tri.= Trichlorethylene Test Content Opacity in % Brabender Impact No. in % of torsional strength EHA • AMA 1mm plate 4mm plate mkp kpcm/cm^ 03 7»1 0,16 13 38 2,4 51,5 77 11 8,6 0,20 14 47 2,0 39,5 74 12 7,1 0,07 11 33 2,85 42,8 78 09 7,3 0,07 11 38 2,35 34,4 76 13 6,8 0,07 16 46 1,95 19,6 75 AMA = Allyl methacrylate EHA = 2-ethylhexyl aerylate For purposes o compar son, v ny c or e was po ymerised in accordance with the previously known process in the presence of a dispersion of 2-ethylhexyl aerylate polymer (T st No. 52, 53, 54) or in the presence of a dispersion of 2-ethylhexyl acrylate/C-methylstyrene copolymer (Test No. 55, 56, 57, 58) or in the absence of dispersions of polymers of acrylic ester polymers (Test No. 51).

Further, a copolymer of 2-ethylhexyl acrylate and ethyl-eneglycol dimethacrylate, that is, a poly-functional combination not in accordance with the invention was added as the acrylic ester polymer (Tests No. 59 and 60).

The formulae for the polymerisation and the results are given in .Table 5. In no case were very high impact strengths or low opacities obtained simultaneously with high impact strengths, as is the case when the copolymers in accordance with the invention comprising acrylic esters and poly-functional allyl compounds were employed.

Test Pre-dispersion Water LS NaOH PS VC Temp, IN No. Particle o & 9 g ml g g °C ^ diameter niD 0 51 - - 0 5940 12 60 2 2000 59 52 H 60 -560 5470 9 50 2 1900 59 53 H 60 700 5450 9 50 2 1900 59 54 H 60 910 5170 8 45 2 1870 59 55 J 60 560 5480 10 60 2 1900 59 56 J 60 700 5380 9 50 2 1870 59 57 J 60 910 5210 8 45 2 1830 59 58 J 60 1190 5000 7 40 2 1780 .59 59 K 71 910 5210 8 45 2 1870 59 60 71 1190 5000 7 40 2 1780 59 KPS = Potassium persulphate LS = Laurie acid Test Content Opacity No. in % of in % EHA MS Poly- unct . 1 mm 4 mm monomer plate plate mkp 51 0,0 0,0 - 0,0 3 4 n.b. 3,0 76 52 4,9 0,0 - 0,0 18 n. b. n.b. 10,6 75 • 53 6,0 0,0 - 0,0 21 n.b. n.b. 14,2 75 54 7,4 0,0 - 0,0 40 n.b. n.b. 17,2 75 55 5,2 1,6 - 0,0 5 14 2,25 8,9 76 56 5,8 1,7 - 0,0 6 14 2,3 11,2 75 57 7,7 2,3 - 0,0 9 25 2,3 12,5 76 58 9,8 3,0 - 0,0 12 31 2,3 23,4 75 59 6,4 0,0 AGDM 0,16 21 66 2,2 31,7 77 60 9,5 0,0 AGDM 0,24 39 88 2,3 30,8 76 AGDM =? ethyleneglycol dimethacrylate EHA = 2-ethylhexyl acrylate MS = ac-methylstyrene n.b. = not determined

Claims (19)

The claims defining the invention are as follows:

1. Process for the manufacture of transparent, impact resistant and weather resistant polymers of vinyl chloride b polymerisation of vinyl chloride, if desired, together with other copolymerisable monomers in aqueous dispersion in accordance with the process of emulsion polymerisation in the presence of copolymers of acrylic esters, characterised in that vinyl chloride or mixtures of monomers with at least 80% by weight of vinyl chloride are polymerised in the presence of a dispersion of at least one copolymer comprising 90 to 99.7% by weight of at least one acrylic ester with 3 to 16 C-atoms in the ester group and 0.3 to 10% by weight of a poly-functional monomer with at least two non-conjugated ethylenic double bonds at least one of which comprises an allyl type, whereby the copolymer exhibits a mean particle diameter determined by means of titration against surface active agents of 30 to 150 nra, preferably 40 to 120 nm, and is used in such amounts that the final polymer, contains 4 to 20% by weight of acrylic ester components.

2. Process in accordance with Claim 1, characterised in that the amounts of copolymers of acrylic esters used are such that the final polymer contains 5 to 10% by weight of acrylic ester components.

3. Process in accordance with Claim l, characterised that the copolymer of acrylic esters used comprises copolymers containing 95 to 99.5% by weight of at least one acrylic ester with 3 to 16 C-atoms in the ester group and 0.5 to 5% by weight of a poly-functional monomer with at least two non-conjuoated ethylenic double bonds, at least one of which comprises an allyl type .

4. Process in accordance with Claim 1 or Claim 3, characterised in that copolymers of acrylic esters are used, in which the acrylic ester component comprises at least one acrylic ester component with 4 to 8 C-atoms in the ester group.

5. Process in accordance with Claim 1 or Claim 4, characterised in that copolymers of acrylic esters are used, which are produced from two different acrylic esters and a poly-functional allyl monomer.

6. Process in accordance with Claim 1 or Claim 3, characterised in that copolymers of acrylic esters are used, which contain as the acrylic ester component at least 90% by weight of 2-ethylhexyl acrylate.

7. Process in accordance with any one of Claims 1 to 6, characterised in that the poly-functional allyl -monomer used comprises one or a number of compounds selected from the class of allyl- or methallyl- e.sters of unsaturated mono-carboxylic acids, the allyl- or methallyl- mono- or di- esters of unsaturated di-carboxylic acids, and the allyl- or methallyl- di-ester, tri-ester or tetra-ester of aliphatic saturated or aromatic polycarboxylic acids, from cyanuric acid and phosphoric acid.

8. Process in accordance with Claim 1 or Claim 7, characterised in that the poly- unct on a y monomer use comprises allyl acrylate or al 1yl, methacrylate.

9. Process in accordance with Claim 1 or Claim 7, characterised in that the poly-functional allyl monomer comprises tri -allyl cyanurate.

10. Process in accordance with Claim 1, characterised in that the emulsion polymerisation of the vinyl chloride or the mixture of monomers is carried out at temperatures from 50 to 70°C.

11. Process in accordance with Claim 1, characterised in that a mixture of monomers comprising 80 to 97% by weight of vinyl chloride and 20 to 3% by weight of flC-olefins is polymerised.

12. Process in accordance with Claim 1, characterised in that a mixture of monomers comprising 80 to 97% by weight of vinyl chloride and 20 to 3% by weight of esters of unsaturated carboxylic acids is polymerised.

13. Process in accordance with Claim 1, characterised in that a mixture of monomers comprising 85 to 99% by weight of vinyl chloride and 15 to 1% by weight of alkylvinyl ether is polymerised.

14. Process in accordance with Claim 1 or Claim 7, charact erised in that the polymerisation is carried out in the presence of salts of fatty acids with 12 to 18 C-atoms in the weight, in relation to vinyl chloride.

15. Process in accordance with Claim 1 or Claim 7, characterised in that the polymerisation is carried out in ^he presence of polymerisation regulators.

16. Process in accordance with Claim 1 or Claim 12, characterised in that the operations are carried out in the presence of mercaptans as regulators, using amounts of O.Ol to 0.2% by weight, in relation to vinyl chloride.

17. Process in accordance with Claim 1 or Claim 12, characterised in that the operations are carried out in the presence of saturated and/or unsaturated halogenated hydrocarbons as regulators, using amounts of 0.1 to 5% by weight, in relation to vinyl chloride.

18. Process in accordance with Claim 1 or Claim 7, characterised in that the catalysts used comprise those capable of producing free radicals and which are soluble in water.

19. Process in accordance with Claim 1, characterise! " that the polymerisation is carried out at absolute rp^'1' ';' which comprise 65 to 95% of the saturation pressure of 1 chloride or the mixture of monomers at the correspond merisation temperature and under the conditions for ennil'-t" polymerisation. For the Applicants Dr. Yi shak Hees