Polymerisation process
United States Patent 1191 Sturt *Apr. 8, 1975 POLYMERISATION PROCESS [56] References Cited [75] inventor: Alan Charles Sturt, Surrey, England UNITED STATES PATENTS 3,583,956 6/l97l Pointer et all. 260/863 [73] Asslgnee&#39; BP chem&#39;cals London 3.725.375 4/1973 Sturt 260/92.8 w  
 England i 1 Notice: The Portion of the term of this Primary E.\&#39;aminer.loseph L. Schofer Patent i q fi to y 1989- Assistant Examiner-John Kight has been dlsclalmed- Attorney, Agent, or Firm-Brooks Haidt &amp; l-laffner [22] Filed: Feb. 5, 1971 211 App]. 110.; 113,066 [57] ABSTRACT Emulsion polyvinyl chloride made usmg a fatty acid salt emulsifying agent is recovered by adding more [52] US. Cl. ..260/29.6 CM, 260/29.6 PM; monomer converting the emulsion to a suspension 260/899 system by the addition of acid and a suspension stabi- I In. li er and polymeri ing the added monomer under Sus- [58] Field of Search 260/928 W, 884  
 pension conditions.  
 5 Claims, No Drawings POLYMERISATION PROCESS The present invention relates to a process for the production of polymeric material by the polymerisation of vinyl chloride in aqueous dispersion.  
  The polymerisation of vinyl chloride in aqueous dispersion is well known. When the dispersion and the produced polymeric vinyl chloride is in the form of fine droplets or particles which have been stabilised by means of emulsifying agents and the like to such an extent that the aqueous dispersion is stable for some time after any mechanical stirring used to maintain it is stopped, the polymerisation process is known as emulsion polymerisation. When the dispersion and the produced polymeric material is in the form of large droplets or particles which coalesce or settle out from the aqueous phase when the mechanical stirring is stopped, the polymerisation process is known as suspension polymerisation. Suspension stabiliser systems are usually present in a suspension process in order to control the particle size and to ensure that the suspension does not break down during polymerisation. The instability of suspension polymerisation processes is particularly marked in the initial stage of the polymerisation, i.e. before 50 percent polymerisation is achieved.  
  Emulsion polymerisation has certain advantages over suspension polymerisation in that it can readily be operated with little reactor fouling at a high ratio of monomeric/polymeric material to aqueous phase. However, when applied to the production of a non-film forming polymer such as PVC, the product is difficult to isolate because of the fine particle size.  
  An object of the present invention is to provide an improved process for polymerisation of vinyl chloride in aqueous dispersion. A further object is to provide a process for the production of vinyl chloride polymers having good processing properties.  
  Accordingly the present invention is a process which comprises polymerising vinyl chloride under emulsion polymerisation conditions using a saturated fatty acid soap emulsifying agent, allowing the emulsion polymer to absorb vinyl chloride monomer, transforming the emulsion system into a suspension system by the addition of acid and polymerising the absorbed vinyl chloride monomer under suspension polymerisation conditions.  
  The vinyl chloride in the first stage polymerisation may, if desired, be mixed with other monomers that are copolymerisable therewith provided that the formed copolymer is a non-film forming copolymer, i.e. has a glass transition temperature (T(.&#39;) above C. Such copolymers are incapable of forming a coherent film when deposited on a suitable substrate from an aqueous emulsion thereof and allowed to dry at temperatures below about 10C, say 5l0C. Examples of suitable comonomers are, methyl methacrylate, vinyl esters such as vinyl acetate and ethyl acrylate, propylene, ethylene. isobutene, and 4-methyl-pentene-l Generally the copolymerisable monomer will not be present in an amount greater than percent by weight of the total weight of vinyl chloride and copolymerisable monomer employed in the first stage emulsion polymerisation.  
 The emulsion vinyl chloride polymer is either present as an emulsified latex or as a suspension when it-ab sorbs the second stage vinyl chloride.  
  The emulsion polymer may be mixed with. other emulsion polymers before the suspension polymerisation stage of ,the process. This technique can lead to the production of useful blended products. The added emulsion polymer need not necessarily be a non-film forming polymer. Useful product blends can be formed by adding to the emulsion vinyl chloride polymer any of the known polyvinyl chloride additives that are available in suitable aqueous dispersion. Examples of such additives are toughening agents such as ethylene/vinyl acetate copolymers and process aids such as styrene/acrylonitrile copolymers and polymethyl methacrylate.  
  The quantity of second stage vinyl chloride monomer is preferably not greater than the amount of monomer that the vinyl chloride emulsion polymer can absorb under the prevailing conditions, although larger amounts can be employed if desired. The weight of monomer employed in the second stage is suitably not greater than the weight of emulsion polymer present. In practice the polymer to monomer ratio lies in the range :50 to 97.525 and is preferably in the range :30 to 92.5:7.5.  
  The vinyl chloride employed in the second stage of the process may contain up to 25 percent weight of a copolymerisable monomer. Preferably pure vinyl chloride is used. This embodiment can lead to a process in which vinyl chloride homopolymer is produced by an emulsion process and recovered in the form of easily handled bead-like particles.  
  The emulsion polymerisation stage of the process must be carried out in the presence of a saturated fatty acid soap emulsifying agent using the well known emulsion polymerisation techniques. These are, for example, described in volume IX of the series of monographs on the chemistry, physics and technology of high polymeric substances published by lnterscience Publishers, Inc., New York.  
  Conventional components of vinyl chloride polymerisation systems can be present in the emulsion polymerisation stage of the present invention, e.g. polymerisation initiator systems, preferably watersoluble, molecular weight modifiers and the like. Conventional phase ratios of organic to aqueous phases can be employed.  
  The second stage vinyl chloride may be added to the emulsion polymer latex, or, preferably, the vinyl chloride emulsion polymer may absorb vinyl chloride as it is formed and thus during the emulsion polymerisation stage a point will arise when the formed vinyl chloride polymer will have adsorbed therein a minor proportion of vinyl chloride. Thereafter and at any time subsequently while the polymerisation system contains vinyl chloride the emulsion polymerisation system can be transformed into a suspension sustem according to the present invention.  
  In order to transform the emulsion system into a suspension system, it is preferred to destroy the emulsion in the presence of a suspension stabiliser system in order to prevent complete coagulation of the vinyl chloride polymer. However, by careful control of the agitation to which the polymerisation system is subjected it is possible to transform the emulsion system to a suspension system in the absence of a suspension stabiliser.  
  The emulsion system is transformed by reducing the efficiency of the emulsifying agent employed by adding an acid to the system. The fatty acid soap emulsifying ylic acid soap emulsifying agents are the alkali metal or ammonium salts of lauric acid, stearic acid, palmitic acid and myristic acid. The added acid is preferably water-soluble. Examples of preferred acids are acetic, propionic and phosphoric acids. Other examples are acid phosphate salts and sulphuric and hydrochloric acids.  
  A suspension stabiliser system must be present during the second stage of the process of the present invention in order to ensure that the polymerisation of the second monomer takes place under suspension polymerisation conditions. Suspension stabiliser systems are well known and can contain suspending agents of the organic or inorganic type and can be water soluble or insoluble. Examples of suitable organic suspending agents are polyvinyl alcohol, partially hydrolysed polyvinyl acetates. salts of styrene-maleic anhydride copolymers, gelatin, cellulose ethers such as methyl cellulose. hydroxypropyl methyl cellulose and hydroxyethyl cellulose. Mixtures of organic and inorganic suspending agents and of water soluble and insoluble suspending agents can be used.  
  Conventional suspension polymerisation conditions can be employed in the final polymerisation stage of the process of the present invention. It is possible to use a higher ratio of organic phase to aqueous phase than can be used in processes in which the vinyl chloride is polymerised entirely under suspension conditions. Thus it is possible to convert a highly concentrated emulsion polymerisation system to a suspension system without necessarily having to add further quantities of water.  
  In the polymerisation of the absorbed monomeric material. it is preferred to employ a polymerisation initiator. As is conventional in suspension polymerisation systems, the polymerisation initiator is most suitably soluble in the absorbed monomeric material.  
  The product of the process of the present invention can be isolated by the means conventionally used for suspension polymers. The products behave like conventional suspension polymers in that they can be readily washed and can be recovered by simple filtration or decantation techniques. Moreover the individual polymer particles retain their identity in suitable recovery processes. This is in marked contrast to the polymeric material recovered from conventional emulsion polymerisation processes by coagulation. for example by the addition of an electrolyte. of the emulsion polymer particles in the aqueous latex. The coagulum frequently is in the form of a cream in which it is difficult to wash the polymer and from which it is difficult to isolate dry polymer. Moreover, the isolated product tends to break down again to particles of emulsion polymer size when subjected to shear during conventional heating and drying procedures.  
  Vinyl chloride polymers produced according to the present invention are particularly valuable in that they have rapid fusion times. i.e. when subjected to work in a heated pressure forming machine they rapidly fuse and readily flow in the machine. The property of improved fusion times is retained in the presence of lubricants which, in conventional vinyl chloride polymers. tend to increase fusion times. The addition of vinyl chloride polymers according to the present invention to conventional vinyl chloride polymers gives blends that have surprisingly low fusion times.  
  The present invention is illustrated by the following examples in which the parts quoted are by weight.  
 EXAMPLE 1 Vinyl chloride was polymerised in aqueous emulsion using ammonium stearate as the emulsifying agent to give a latex having a polymer content of 37 percent. A suspension resin was then made from 75 parts of this PVC latex (dry weight) and parts of vinyl chloride with the following recipe.  
 Vinyl chloride l75 g. Distilled water 1925 g. PVC latex (37% solid) L400 g. Elvanol 5()-42* 7 g. Acetic acid [07: w/w) 70 ml. Lauroyl peroxide 2 g.  
 Polyvinyl alcohol. partly hydrolysed. medium viscosity.  
  The latex was added with stirring to a solution of the polyvinyl alcohol in a litre of the distilled water. This gave a mixture of pH 9.8. The acetic acid solution was then added slowly with stirring which reduced the pH to 5.  
  Next the mixture was charged into a stainless steel reactor with the initiator and the remainder of the water. The reactor was purged with nitrogen and evacuated. and then vinyl chloride was sucked into the reactor. To effect polymerisation the reactor was heated at C for 6 hours while stirring at 700 r.p.m. After 6 hours the reactor was cooled and the residual monomer vented off.  
  The product was readily filtered and washed on the filter. The dry material weighed 610 g. and examination by scanning electron microscope showed that it contained particles ranging from 20 to 100 p..  
 EXAMPLE 2 A suspension resin was made from 90 parts (dry weight) of the PVC latex described in Example 1 and 10 parts of vinyl chloride with the following recipe.  
 Vinyl chloride g. Distilled water L630 g. PVC latex (37% solid) L800 g. Polyvinyl alcohol as Example 1 7 g. Acetic acid 10% w/w) ml. Lauroyl peroxide 2.0 g.  
 The procedure was as described in Example 1. After 6 hours at 60C the reactor was cooled and vented.  
  The product was again readily filtered and washed on the filter. After drying in a vacuum oven at 45C for 48 hours the product weighed 700 g. Examination by scanning electron microscope showed that it consisted of particles ranging from 20 to EXAMPLE 3 A resin was made from 75 parts (dry weight) of PVC latex described in Example 1 and 25 parts of vinyl chloride with the following recipe.  
  The polyvinyl alcohol was dissolved in the distilled water and the sodium hydroxide added to raise the pH from 5.3 to 10. The latex was added to that solution and stirred thoroughly. This mixture was charged into a stainless steel reactor together with the initiators. The reactor was purged with nitrogen and evacuated, and the vinyl chloride was sucked in. The charge was stirred at 120 r.p.m. for 30 minutes, during the last minutes of which the acetic acid solution was pumped in.  
  The stirrer speed was then increased to 700 r.p.m. and the charge heated at 60C for 6 hours during which the polymerisation took place. After this period the charge was cooled and vented to atmospheric pressure.  
  The product was easily filtered and washed on the filter. After drying in a vacuum oven at 45C for 48 hours 656 g. of product were obtained. Microscope examination showed that the particles ranged from 40 to 200 [.L.  
 EXAMPLE 4 A resin was made from 90 parts (dry weight) of the PVC latex described in Example I and 10 parts of monomer with the following recipe.  
 Vinyl chloride Distilled water PVC latex (36.5% solid) Alcotex 8840* Lauroyl peroxide Polyvinyl alcohol. 88&#39;; hydrolysed. medium viscosity.  
  The polyvinyl alcohol was dissolved in 4 litres of water and the solution was poured into a stainless steel reactor. The remainder of the water. the initiator and the latex were then added and the reactor purged with nitrogen. The vinyl chloride was sucked into the reactor and the mixture was stirred at 700 r.p.m. The charge was heated at 60C for 6 hours, and then cooled and vented to atmosphere.  
  The product was easily separated from the aqueous phase by basket centrifuge. and it was washed with water in the centrifuge. A yield of 3,370 grams of dry product was obtained. Microscopic examination showed that the particle sizes ranged from to 60 p.-  
 EXAMPLES 5 to 14 In the examples two general methods were employed as set out below as methods A and B to treat various polyvinyl chloride emulsion polymers (latices) with vinyl chloride and then recover polymer in suspension form after completing the process according to the present invention. The latices were prepared by normal emulsion polymerisation techniques using the emulsifying agents indicated. Various commercial chemicals were used. Their chemical names are as follows:  
 Commercial Name Chemical Name Goshenol Poly( vinyl alcohol) Perkadox Y 1 6 Ditertiarybutylcyclohexyl peroxydicarbonate Alcotex 88-10 Poly(vinyl alcohol) 887: hydrolysed, medium viscosity Hydroxyethyl cellulose,  
  medium viscosity Hydroxypropylmethyl cellulose. medium viscosity.  
 C ellosize QP4400 Methocell HG METHOD A The suspending agent(s) was dissolved in the distilled water. The latex was added to the stirred solution. The acetic acid solution was added slowly with stirring so as to reduce the pH of the solution to 5.  
  The mixture was charged into a stainless steel reactor, together with the initiator. After purging and evacuating the reactor. the vinyl chloride was sucked in. The polymerisation was performed by heating the reactor at 60C for 6 hours while stirring at the stated stirrer speed.  
  After 6 hours the reactor was cooled and the residual monomer was vented off.  
  The product was easily separated from the aqueous phase by basket centrifuge and was washed with water in the centrifuge. It was then dried in a vacuum oven at 45C.  
 METHOD B The suspending agent(s) was dissolved in the distilled water and the latex added to the stirred solution. The mixture was charged into a stainless steel reactor with the initiator.  
  The mixture was stirred at 300 r.p.m. (unless otherwise stated) for 15 minutes during the last 10 minutes of which the acetic acid solution was added. The reactor was purged with nitrogen and evacuated. The vinyl chloride was then sucked into the reactor.  
  The polymerisation was then performed by heating the reactor at the stated temperature for the stated time while stirring at the stated stirrer speed. After this period. the reactor was cooled and the residual monomer vented off.  
  The product was easily separated from the aqueous phase by basket centrifuge and was washed with water in the centrifuge. It was then dried in a vacuum oven at 45C.  
 EXAMPLE 5 Method A was applied to the following materials using a stirrer speed of 600 r.p.m. for the suspension polymerisation.  
 Vinyl chloride/PVC ratio The emulsifier was ammonium laurate. The yield of polymer was 329 grams.  
 EXAMPLE 6 EXAMPLE 10 Method A was applied to the following materials Method was applied to the following materials. using a stirrer speed of 600 rpm. for the suspension polymerisation.  
  Vinyl chloride 225 g. PVC latex (31.671 solids) 870 g. Distilled water 2,000 g. Vlnyl chlorlde l75 g. Alcotex 88-10 3 g. Distilled water 1000 g. Lauroyl perqxide 0.5 g. PVC latex (33% solid) 1.200 g. Perkadox Yl6 l g. Celloslze QP44 0 g- Acetic acid (10% w/w) 200 ml. Methocell 65HG50 g- Stirrer speed 700 r.p.m. Ac tic acld I 7: WM) 30 ml? Yield after 4 /2 hours at 50C 379 g. Lauroyl peroxide l g. Vinyl chloride/PVC ratio 30/70 EXAMPLE ll The emulsifier in the latex was ammonium stearate. The yield of polymer was 466 grams.  
 Mmethod B was applied to the following materials.  
 EXAMPLE 7 Method A was applied to the following materials viny|ch|mide 135 using a stirrer speed of 700 r.p.m. for the suspension PVC latex Sohds) Alcotex 88-10 7 g. polymeflsatlon- Distilled water 1.800 g. Perkadox Yl6 l g. Lauroyl peroxide 0.2 g. Acetic acid KW: w/w) 250 ml. Stirrer speed 700 rpm. Vlnyl chloride 40 g. v e Distilled water 270 g Yleld after 6 hours at 50 C 50- g. PVC latex (2971 solid) 2.660 g. Alcotex 88-10 l.75 g. Acetic acid (l0&#39;/zw/w) 150 ml. Lauroyl peroxide l g. EXAMPLE 12 Vinyl chloride/PVC ratio 5/95 Method B was applied to the following materials.  
 The emulsifier was ammonium stearate. The yield of polymer was 562 grams.  
  Vinyl chloride I25 g. Distilled water 2.000 g. EXAMPLE 8 Methocell65HG 0.8 g. Cellosize QP4400 1.2 g. Method B was applled to the following materials. PVC latex (2M7! Solids) L000 g Perkadox Yl6 l g. Acetic acid l07r w/w) 220 ml. Stirrer speed 700 rpm vinyl chloride 600 g Yield after 6 hours at 50C 302 g. Distilled water 2000 g. PVC latex (29171 Solids) 950 g. Goshenol 3.5 g. Gelatin 3.5 g. Acetic acid (10% w/w) 230 ml. EXAMPLE l 5: min 0/75 E Method B was applied to the following materials. Stirrer speed 700 rpm.  
  V &#39;l hl d The emulsltiers in the latex were ammonium myrls- 3 8 f jfflgj solids) g tate and palmltate. The yleld of polymer was 569 grams Goshenol 3 5 g, after 6 hours at C 50 Dlstlled 1.300 g.  
 &#39; Acetic acid l07: w/w) 200 ml.  
  Perkadox Yl6 0.3 g. EXA L 9 Stirrer speed 700 rpm Yield after 6 hours at 50C 728 g.  
 Method B was applied to the following materials.  
  EXAMPLE l4 Vinyl chloride 235 g PVC latex (30.571 solids) 900 2 Method B was applied to the following materials. Methocell 65HG50 0.8 g. Cellosize QP4400 l.2 g. Distilled water L900 g. Lauroyl peroxide l g. Acetic acid I071 w/w) 250 ml. Vinyl chloride 225 g. Vinyl chloride/PVC ratio 45/55 PVC latex (32.57: solids) 850 g. Methocell HG 0.8 g. Cellosile QP4400 l 2 g. Distilled water 1.950 g. The emulslfiers ln the latex were ammonium stearate 6S Laumy] peroxide and ammonium laurate. Qs t I094 g0!) ml.  
  tlrrer spec 00 r. .m. Suffer Speed 600 -P- Yield after 8 hours in 60C 435 g.  
 Yield 400 g. after 6 hours at 60C.  
  In all examples to 14 inclusive the product was obtained in a suspension form and could be easily collected and washed in the basket centrifuge. In contrast to this attempts to isolate polyvinyl chloride from the latices used in these examples after coagulation of the emulsion particles gave rise to creams that were difficult to wash and agglomerated products which broke down to very fine particles when subjected to shear.  
 EXAMPLE A suspension resin was made by first making a PVC latex containing free vinyl chloride and then incorporating it in situ into a suspension polymerisation with more vinyl chloride.  
 The overall charge was Vinyl chloride l.l00 g. Distilled water 2.500 g. Stearic acid 60 g. Ammonia (0.88) I ml. Ammonium persulphate 0.2 g. Sodium metabisulphite 0.05 g. Alcotex 88-10 5.5 g. (ilacial acetic acid 60 ml. Lauroyl peroxide 1 g.  
  The ammonia. stearic acid (forming ammonium stearate as the emulsifying agent) and ammonium persulphate, sodium metabisulphite and 2.000 ml. of distilled water were charged to a stainless steel reactor. The reactor was sealed, purged with nitrogen and evacuated. 1.000 g. of the vinyl chloride was sucked into the reactor and the charge stirred at 300 r.p.m. The charge was heated at C for 8 hours after which time it was evident that the maximum conversion (about 92 percent) had been reached (this was indicated by the solids content remaining constant at about 30.8 percent.)  
  The poly(vinyl alcohol) was dissolved in 250 ml. of distilled water and the solution mixed with the glacial acetic acid. The mixture was pumped into the reactor over a period of 30 min. and the remaining 250 ml. of distilled water was pumped in afterwards over a period of 25 min.  
  The lauroyl peroxide was dissolved in 100 g. of vinyl chloride monomer and this solution was pumped into the reactor.  
  The stirrer speed was increased to 600 r.p.m. and the temperature of the reactor increased to 60C. The charge was held at 60C for 9 /2 hours. After this period the charge was cooled and the residual monomer vented off.  
  The product was easily separated from the aqueous phase by basket centrifuge and was washed with water in the centrifuge. It was then dried in a vacuum oven at 45C. The yield was 988 g.  
 EXAMPLE 16 A suspension resin was made from parts ofa PVC latex (dry weight) and 45 parts of vinyl chloride with the following recipe Vinyl chloride 225 g. PVC latex (31.5% solids) 870 g. ALcotex 88-10 3.5 g. Distilled water 1.000 g. Orthophosphoric acid I092 85 ml. Caprylyl peroxide l g.  
 The emulsifier in the latex was potassium laurate.  
  The poly(vinyl alcohol) was dissolved in the distilled water and the latex added to the solution. The mixture together with the caprylyl peroxide was charged into a stainless steel reactor. The charge was stirred at 300 r.p.m. for 20 min. during the last 10 min. of which the orthophosphoric acid was added. The reactor was purged with nitrogen and evacuated. The vinyl chloride was then sucked into the reactor.  
  The polymerisation was then performed by heating the reactor at 60C for 8 hours while stirring the charge at 700 r.p.m. After 8 hours, the charge was cooled and the residual monomer vented off.  
  The product was easily separated from the aqueous phase by basket centrifuge and was washed with water in the centrifuge. It was then dried in a vacuum oven at 45C. The yield was 418 g.  
 EXAMPLE 17 A suspension resin was made from 55 parts of PVC latex (dry weight) and 45 parts of vinyl chloride with the following recipe:  
 Vinyl chloride 225 g. PVC latex (28.87: solids) 955 g. Cellosize QP4400 l.2 g. Methocell HG 0.8 g. Distilled water 1.900 g. orthophosphoric acid (10%) 390 ml. Perkadox Ylo l g.  
 The emulsifier in the latex was ammonium laurate.  
  The hydroxyethyl cellulose and hydroxypropylmethyl cellulose were dissolved in the distilled water and the latex added to the solution. This mixture together with the Perkadox Y 1 6 was charged into a stainless steel reactor. The charge was stirred at 300 r.p.m. for 20 min. during the last 10 min. of which the orthophosphoric acid was added. The reactor was purged with nitrogen and evacuated. The vinyl chloride was then sucked into the reactor.  
  The polymerisation was then performed by heating the reactor at 50C for 10 hours while stirring the charge at 700 r.p.m. After 10 hours, the charge was cooled and the residual monomer vented off.  
  The product was easily separated from the aqueous phase by basket centrifuge and was washed with water in the centrifuge. [t was then dried in a vacuum oven at 45C. The yield was 447 g.  
 EXAMPLE 18 A suspension resin was made from 90 parts of a polyvinyl chloride latex (dry&#39; weight) and 10 parts of vinyl chloride with the following recipe.  
 Vinyl chloride g. PVC latex (34.571 solids) L800 g. Distilled water 1.630 g. Elvanol 5042* l Acetic Acid (i071 w/w) ml. Lauroyl Peroxide 2 g.  
 Poly-(vinyl alcohol). partly hydrolysed. medium viscosity.  
  The emulsifier in the latex was ammonium stearate. The polyvinyl alcohol was dissolved in the distilled water and the latex added to the solution and stirred thoroughly. This mixture was charged into a stainless steel reactor together with the initiator. The reactor was purged with nitrogen and evacuated and the vinyl chloride was sucked in.  
  The charge was stirred at 120 r.p.m. for 30 minutes during the last 10 minutes of which the acetic acid solu- Table 2 gives the fusion times in minutes for various mixturesof Breon 115 with a commercially available emulsion polyvinyl chloride polymer (Vestolit G), the spray dried polymer from the latex used in examples 6 and 19 and the products of examples 6 and 19. The fortion was pumped in. The stirrer speed was then in- 5 creased to 700 rpm. and the charge heated at 60C for mulanon used was 6 hours during which polymerisation occurred. After Breon I15 (I X parts by weight that period the charge was cooled and vented to atmog l i I 1:352; spheric pressure, Tin stabiliser 1.5 parts by weight The product was readily filtered and washed on the (Meme 3]) filter. After drying in a vacuum oven at 45C. the prodm 3 uct welghed 685 g. Value x Added Polymer I I EXAMPLE l9 Vesolrt Sprpgtgned Example I) Example 6 A suspension resin was made from 90 parts of a polyl5 0 54 54 54 54 1 v1nyl chlor1de latex (dry weight) and 10 parts of vinyl 50 62 3 2 chloride with the following recipe. 40 120 120 3 50 6.2 13 L5 2 7 Table 3 gives the fusion time in minutes for various Vin chloride 600 y m1xtures compounded as in table 2 of Breon 115 with PVC mm (367, 50nd) 5000 the spray dried polymer from the latex used in example Distilled water 3.600 Q. 19 and the product of example 19 at a lubricant level Q fgE f fF w/ I 88 s of 0.5 parts by weight of stearic acid and a tin stabilizer 3H? l m content of 1.5 parts by we1ght. Table 3 The emulsifier in the latex was ammonium stearate. lue of x Spray-dried atex Example I) The procedure was the same as in Example 18 but 0 3 3 product was dried in air-circulating oven at 50C. lg g as The yield was 5,616 g. 5 The product of examples 6, l8 and I9 were tested as 4 lmmedime described below in a Brabender for fusion times and compared with conventional polyvinyl chloride polylclaim; mers. The Brabender was operated under the following 1, A ro e which comprises polymerising vinyl conditions: chloride under emulsion polymerisation conditions using a saturated fatty acid soap emulsifying agent. allowing the emulsion polymer to absorb vinyl chloride gl l f monomer in an amount so that the polymer to mono- Mill-E il 3i) r.p.m mer ratio lies in the range of from about 70:30 to Charge 32 grams 92527.5, transforming the emulsion system into a suspension system by the addition of acid and polymeris- The polyvinyl chloride polymers were compounded beg t absorbed vinyl 0 m n m Under 81 8- f testing as f pension polymer1sat1on conditions.  
  2. A process as claimed in claim 1 wherein the sec- 0nd monomeric material is pure vinyl chloride. Polymer 101) parts by weight 3. A process as claimed in claim 1 wherein the secg f&#39;l f l fj l y .P5&#39; weig t and stage monomeric material comprises unpolymer- Mm m ised vinyl chloride from the first stage polymerisation.  
 . 4. A process as claimed in claim 1 wherein the satu- Table l glves the fuslon times In minutes of three rated fatty acid soap emulsifying agent is an alkali Commerclal Polyvmyl lmlymers f metal or ammonium salt oflauric acid.stearic acid,pal- Breon 113 (sold by BP Chemicals lnternat1onal L1mmitic acid or myristic acid ited) and D 65/6 (sold by Imperial Chemical Industries 5, A process as Claimed in claim 1 wherein the acid Limited) the spray-dried polymer obtained from th used to transform the emulsion system into a suspenlatex used in Examples 6 and 18 with the fusion time sion system is acetic acid, propionic acid or phosphoric of the products of examples 6 and 18 at varying levels acid. of added lubricant.  
 Table l Lubricant.  
 parts per Breon 1 l5 Breon I I3 D 65/6 Sprayalried Examples hundred latex 6 I 8 polymer 0.5 6 9.5 not 6 I not tested tested 1.0 60 10.5 I l 2.( l l 4.11 1 1 I Immediate.  
  UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,876,597  
 DATED 1 April 8, 1975 INVENTOR(S) ALAN CHARLES STURT It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 Col. 8, Example 10, line 2, after &#34;Method&#39; insert B Col. 8, Example 11, line 16, correct the spelling of &#34;Method&#34;.  
 Signed and Scaled this thirtieth Day of September1975 [SEAL] A lies I:  
 RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmisximwr of Parents and Trademarks