MXPA99004197A - Continuous process to produce polimero cauchot - Google Patents

Abstract

The present invention relates to: There is a need for polymers that are used in automobile interiors that offer increased resistance to heat and ultraviolet light. It is particularly critical for polymers that are used in making skin compounds for panels and instruments and automotive doors to exhibit excellent resistance to value and ultraviolet light. This invention describes a continuous process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin-like compositions having good resistance to heat and ultraviolet light. This technique involves using a system of multiple continuous reactors wherein a first phase monomer solution containing butyl acrylate, an acrylic monomer, acrylonitrile and a crosslinking agent is continuously charged to at least three initial reactors. To achieve a small particle size, it is necessary to limit the solids content in each of these initial reactors. Then, a second phase monomer solution containing styrene, additional acrylonitrile and additional crosslinking agent is continuously charged to a subsequent reactor. This technique can also be used to synthesize core / shell structures or IPN using multi-stage emulsion polymerization in which the first stage latex contains a majority of butyl acrylate with a small latex particle size being obtained

Description

CONTINUOUS PROCESS TO PRODUCE CAUCHOTOSO POLYMER BACKGROUND OF THE INVENTION Automotive instrument panels and door panels are typically composite which are made of a rigid reinforcement that supports a semi-rigid urethane foam with the semi-rigid urethane foam being covered with a skin composite. These skin compounds are typically mixtures of polyvinyl chloride (PVC) with a nitrile rubber (NBR). Nitrile rubber is included in such blends as a permanent modifier for PVC that provides it with a higher degree of flexibility. The automotive industry is currently moving towards more aerodynamic body designs that typically include larger glass areas. These design changes have significantly increased the heat and ultraviolet light aging requirements of automobile interiors. This, in turn, has significantly increased the demands imposed on polymers that are used as skins in automotive interior panels. The heat and light stabilizers can be used to improve the aging characteristics of ultraviolet light and heat of conventional PVC / mixtures. NBR that are used as skins for automotive interior panels. however, the degree to which the aging characteristics of these mixtures can be improved by the addition of additives is limited. In fact, there is a demand for operating characteristics in such applications that has not been done so far - through the use of heat and light stabilizers. For example, it would be highly desirable that skins used in automotive panels resist fading and cracking under conditions of high heat and intense ultraviolet light throughout the life of the vehicle. The NBR / PVC blends offer a physical property arrangement that makes them useful as a skin composition for automobile panels. The NBR acts as a permanent flexibilizing monomer for PVC. It also acts as a control agent for shrinkage and enhancement aid and improves grain retention. The NBR in said blends also provides vacuum gauge control and exhibits low nebulosity characteristics. The NBR is highly compatible with PVC and has the ability to recycle. It is essential for any polymer that is replaced by NBR to exhibit these essential characteristics. U.S. Patent 5,380,785 discloses a rubbery polymer that can be mixed with polyvinyl chloride to make skin type compositions having good resistance to heat and ultraviolet light, said rubbery polymer being comprised of repeat units that are comprised of (a) butyl acrylate or optionally a mixture of butyl acrylate and 2-ethylhexylacrylate containing up to about 40 percent of 2-ethylhexylacrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate and ethylacrylate. (c) acrylonitrile, (d) styrene, (e) a medium ester maleate soap and (f) a crosslinking agent. U.S. Patent 5,380,785 further discloses a process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin-like compositions having good resistance to heat and ultraviolet light, the process comprising the steps of (1) polymerizing (a) ) butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40 percent of 2-ethylhexylacrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate and ethylacrylate, ( c) acrylonitrile and (d) a crosslinking agent under emulsion polymerization conditions to produce a latex containing seed polymer; (2) add (a) styrene, (b) additional acrylonitrile and (c) additional crosslinking agent to the latex containing seed polymer under emulsion polymerization conditions resulting in the formation of an emulsion containing the rubbery polymer; and (3) recovering the rubbery polymer from the emulsion containing the rubbery polymer. The process described by US Pat. No. 5,380,785 for synthesizing this rubbery polymer is a batch and semi-continuous process. U.S. Patent 5,616,651 describes a technique for deodorizing the latex of said rubbery polymers by treatment with an aminoalcohol. U.S. Patent 5,616,651 more specifically discloses a process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin-like compositions having good resistance to heat and ultraviolet light, said process comprising the steps of (1) polymerizing (a) butyl acrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate and ethylacrylate. (c) acrylonitrile, (d) a crosslinking agent and (e) a medium ester maleate soap under emulsion polymerization conditions to produce a latex containing seed polymer; (2) add (a) styrene, (b) additional acrylonitrile, and (c) additional crosslinking agent to the latex containing seed polymer under emulsion polymerization conditions resulting in the formation of an emulsion containing the rubbery polymer; (3) adding an aminoalcohol to the emulsion containing the rubbery polymer; and (4) recovering the rubbery polymer from the emulsion containing the rubbery polymer. U.S. Patent 5,674,933 discloses a low cloudiness rubbery polymer which can be mixed with polyvinyl chloride to make skin-like compositions having good heat and ultraviolet light resistance, the rubbery polymer being comprised of repeat units which are comprised of (a) butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexylacrylate containing up to about 40 percent 2-ethylhexylacrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate. methylacrylate and ilacrylate, (c) acrylonitrile, (d) styrene, (e) a surfactant selected from the group consisting of sulphonate and sulfate derivatives, (f) a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates and (g) a crosslinking agent. U.S. Patent 5,674,933 further discloses a process for preparing rubbery polymer that can be mixed with polyvinyl chloride to make skin-like compositions having good resistance to heat and ultraviolet light. This process comprising the steps of (1) polymerizing (a) butylacrylate. (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate. methylacrylate and ethylacrylate, (c) acrylonitrile, (d) a crosslinking agent and (e) a surfactant selected from the group consisting of sulfonates and sulfate derivatives, (f) a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates, under emulsion polymerization conditions to produce a latex containing seed polymer; (2) add (a) styrene, (b) additional acyloni and (c) additional crosslinking agent to the latex containing seed polymer under emulsion polymerization conditions resulting in the formation of an emulsion containing the rubbery polymer; (3) adding an aminoalcohol to the emulsion containing the rubbery polymer; and (4) recovering the rubbery polymer from the emulsion containing the rubbery polymer. The process for producing the rubbery polymer described in this patent, of course, is a batch and semi-continuous process.

SUMMARY OF THE INVENTION The present invention relates to a continuous process for synthesizing rubbery polymers that can be mixed with PVC to make skin-like compositions. These compositions are particularly useful for manufacturing skins for automotive interior panels. Skin compositions made using this rubbery polymer provide a superior level of heat and ultraviolet light resistance than those made using conventional NBR / PVC blends. The rubbery polymers of this invention also offer low haze, low odor, and control characteristics. of shrinkage and grain retention. They also act as an enhancement aid and as a permanent flexibilization modifier. The rubbery polymers of this invention also have characteristics that make them useful in the construction of packaging applications.

This invention more specifically describes a process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin-like compositions having good resistance to heat and ultraviolet light, the process comprising carrying out continuously the steps of (1) loading (a) butylacrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate and ethylacrylate, (c) acrylonitrile monomer, (d) a crosslinking agent, (e) a sulfonate surfactant, (f) a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates to a first polymerization zone, (g) water and (h) a free radical generator; (2) allow the monomers to be polymerized in the first polymerization zone under emulsion polymerization conditions at a monomer conversion of at least about 80 percent to produce a low solids polymerization medium having a solids content of no more than about 10 percent; (3) charge (a) a low solids polymerization medium, (b) additional butylacrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer, and (e) additional crosslinking agent to a second polymerization zone; (4) allow the monomers to be polymerized in the second polymerization zone under emulsion polymerization conditions a, a conversion of monomers of at least about 80 percent to produce a medium solids polymerization medium having a solids content of no more than about 20 percent; (5) loading (a) the intermediate solids polymerization medium, (b) additional butylacrylate monomer, (c) additional acrylate monomer, (d) monomer d? additional acrylonitrile; and (e) additional crosslinking agent to a third polymerization zone; (6) allow the monomers to be polymerized in the third polymerization zone under emulsion polymerization conditions at a monomer conversion of at least about 80 percent to produce a high solids polymerization medium having a solids content of no more than about 30 percent; (7) loading (a) the high solids polymerization medium, (b) styrene, (c) additional acrylonitrile and (d) further crosslinking agent into a fourth polymerization zone; (8) allowing the monomers to polymerize in the fourth polymerization zone under emulsion polymerization conditions at a monomer conversion of at least about 80 percent to produce an emulsion containing the rubbery polymer; and (9) rering the rubbery polymer from the emulsion containing the rubbery polymer. The present invention further discloses a process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin type compositions that have good resistance to heat and ultraviolet light., the process comprising carrying out with the steps of (1) loading (a) butylacrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate and ethylacrylate, (c) acrylonitrile monomer, (d) a crosslinking agent, (e) a sulfonate surfactant, (f) a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates to a first polymerization zone ( g) water and (h) a free radical generator; (2) allow the monomers to be polymerized in the first polymerization zone under emulsion polymerization conditions at a monomer conversion of at least about 80 percent to produce a low solids polymerization medium having a solids content of no more than about 10 percent; (3) charge (a) the low solids polymerization medium, (b) additional butylacrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer and (e) additional crosslinking agent to a second zone of polymerization; (4) allow the monomers to be polymerized in the second polymerization zone under emulsion polymerization conditions at a monomer conversion of at least about 80 percent to produce an intermediate solids polymerization medium having a solids content of no more than about 20 percent; (5) charge (a) intermediate solid polymerization medium, (b) additional butylacrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer, and (e) additional crosslinking agent to a third zone of polymerization; (6) allow the monomers to polymerize in the third zone, from polymerization under emulsion polymerization conditions to a monomer conversion of at least about 80 percent to produce a high solids polymerization medium having a solids content of no more than about 30 percent; (7) loading (a) the high solids polymerization medium, (b) styrene, (c) additional acrylonitrile and (d) further crosslinking agent into a fourth polymerization zone; (8) allowing the monomers to be polymerized in the fourth polymerization zone under emulsion polymerization conditions at a monomer conversion of at least about 80 percent to produce an emulsion containing rubbery polymer; (9) adding an aminoalcohol to the emulsion containing the rubbery polymer; and (10) recovering the rubbery polymer from the emulsion containing the rubbery polymer.

Detailed Description of the Invention The rubbery polymers that can be mixed with polyvinyl chloride to make skin type compositions having good resistance to heat and ultraviolet light can be synthesized by a continuous, free radical emulsion polymerization process, using the technique of this invention. These rubbery polymers are comprised of repeating units which are derived from (a) butyl acrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl acrylate, (b) methyl methacrylate. ethyl methacrylate, methylacrylate or ethylacrylate, (c) acrylonitrile, (d) styrene and (e) a crosslinking agent. The crosslinking agent is typically an ulti functional acrylate, a multi functional methacrylate or divinylbenzene. Some specific examples of crosslinking agents that can be used include ethylene glycol methacrylate, divinylbenzene and 1,4-butanediol dimethacrylate. Technically, the rubbery polymers of this invention contain repeating units (chain links) that are derived from (a) butylacrylate, or optionally a mixture of bu-acrylate and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexylacrylate, (b) methyl methacrylate, ethyl methacrylate, methylacrylate or ethylacrylate, (c) acrylonitrile, (d) styrene and (e) a crosslinking agent. These repeating units differ from the monomers from which they were derived in that they contain a carbon-to-carbon double bond less than that present in the respective monomer. In other words, a carbon-to-carbon double bond is consumed during the polymerization of the monomer to a repeating unit in the rubbery polymer. In this way, by saying that the rubbery rubber? contains various monomers actually means that it contains units of 24 repetition that are derived from those monomers. The rubbery polymers of this invention will normally contain (a) from about 40 weight percent to about 80 weight percent butylacrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to 40 weight percent of 2-ethylhexyl acrylate, (b) from about 5 weight percent to about 35 weight percent methyl methacrylate, ethyl methacrylate, methylacrylate or ethylacrylate, (c) from about 4 weight percent to about 30 weight percent of acrylonitrile, (d) from about 3 weight percent to about 25 weight percent styrene and (e) from about 0.25 weight percent to about 8 weight percent of a crosslinking agent. These rubbery polymers will preferably contain (a) from about 50 weight percent to about 80 weight percent butylacrylate, or optionally a mixture of butylacrylate and 2-ethylhexyl acrylate containing up to about 40 percent by weight. ethylhexyl acrylate, (b) from about 3 weight percent to about 25 weight percent of at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methylacrylate, and ethylacrylate, (c) from about from 6 weight percent to about 30 weight percent acrylonitrile, (d) from about 5 weight percent to about 18 weight percent styrene and (e) from about 0.5 weight percent to about 4 weight percent of a crosslinking agent. The rubbery polymers of this invention will more preferably be comprised of repeating units which are derived from (a) from about 55 weight percent to about 75 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2- ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl acrylate, (b) from about 5 weight percent to about 20 weight percent of at least one member selected from the group consisting of methylmethacrylate, ethyl methacrylate, methylacrylate and ethyl acrylate, (c) from about 10 weight percent to about 25 weight percent acrylonitrile, (d) from about 8 weight percent to about 14 weight percent styrene and (e) from about 1 weight percent to about 3 weight percent of a crosslinking agent. The percentages reported in this paragraph are based on the total weight of the rubbery polymer. The rubbery polymers of the present - íe - invention are synthesized in an aqueous reaction mixture using a free radical polymerization technique. The reaction mixture used in this polymerization technique is comprised of water, the appropriate monomers, an appropriate free-radical initiator, a cross-linking agent, a sulfonate surfactant and a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates. The reaction mixture used in this polymerization technique will usually contain from about 10 weight percent to about 80 weight percent monomers based on the total weight of the reaction mixture. The reaction mixture will preferably contain about 20 weight percent. percent by weight to about 70 weight percent of monomers and more preferably will contain from about 40 weight percent to about 50 weight percent monomers. The reaction mixtures used in carrying out such polymerizations will typically contain from about 0.1 phm (parts per hundred parts of monomer by weight) to about 5 phm from at least one member selected from the group consisting of metal salts of sulfates of alkyl and metal salts of alkyl sulfonates and from about 0.1 phm to about 5 phm of at least one dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates. It is generally preferred that the reaction mixture contain from about 0.25 phm to about 4.25 phm of the metal salt of the alkyl sulfonate or the metal salt of the alkyl sulfate and from about 0.25 phm to about 4.25 phm of the selected dispersant. From the group consisting of aromatic formaldehyde condensation products and polycarboxylates, it is usually more preferred that the reaction mixture contain from about 0.4 phm to about 3.5 phm of the metal salt of the alkyl sulfonate or the metal salt of the sulfate of alkyl and from about 0.4 phm to about 3.5 phm of the dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates. The free radical polymerization technique used in this synthesis is usually initiated by including a free radical initiator in the reaction mixture. Virtually any type of compound capable of generating free radicals can be used as the free radical initiator. The free radical generator is normally used at a concentration within the range of about 0.01 phm to about 1 phm. Commonly used free radical initiators include the various peroxygen compounds such as potassium persulfate, ammonium persulfate, benzoyl peroxide, peroxide and hydrogen, di-t-butyl peroxide, dicumyl peroxide, 2, 4 peroxide. -dichlorobenzoyl, decanoyl peroxide, lauryl peroxide, eumeno hydroperoxide, p-methane hydroperoxide, t-butyl hydroperoxide-, acetyl peroxide. methyl ethyl ketone peroxide, succinic acid peroxide, dicetyl peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroximoleic acid, t-butyl peroxybenzoate, acetyl cyclohexyl sulfonyl peroxide, and the like; the various azo compounds such as 2-t-butylazo-2-cyanopropane, dimethyl azodiisobutyrate, azodiisobutylronitrile, 2-t-butylazo-l-cyano-cyclohexane, 1-t-amylazo-l-cyanocyclohexane, and the like, the various Perketals, such as 2, 2, -bit- (5-butyl-peroxy) butane, and the water-soluble free radical-like peroxygen-initiators are especially useful in such aqueous polymerizations. The emulsion polymerizations of this invention are typically carried out at the temperature ranging from about 20 ° C to 100 ° C. At temperatures above about 88aC, the alkyl acrylate monomers (such as butyl acrylate have a tendency to boil.) Thus, a pressurized jacket would be required to heat said alkyl acrylate monomers to temperatures in excess of about 88 ° C. polymerization temperatures lower than about 55 ° C, an oxidant reduction initiator system is required to ensure satisfactory polymerization regimes A wide variety of crosslinking agents can be used in carrying out the polymerizations of this invention Some representative examples of crosslinking agents which may be used include di-functional acrylates, di-functional methacrylates, tri-functional acrylates, trifunctional methacrylates and divinylbenzene A particularly useful crosslinking agent is 1,4-butanediol dimethacrylate The sulfonate surfactants which are useful in this invention are commercially available dis wearable from a wide variety of sources. For example, duPont sells sodium alkylsulphonate under the trade name Alkanol ™, Bro ning Chemical Corporation sells sodium dodecylbenzene sulphonates under the trade name Ufaryl * ™ Dl-85 and Ruetgers-Nease Chemical Company sells sodium eumeno sulfonate under the trade name Naxonate. Hydrotrope ™. Some representative examples of sulfonate surfactants that may be used include sodium toluene-xylene sulfonate, sodium toluensul-fonate, sodium eumeno sulfonates, sodium decyl-phenylether sulfonate, sodium dodecylbenzenesulfonate, sodium dodecyl diphenylether sulfonate, sodium 1-octane sulfonate. , sodium tetradecano sulfonate, sodium pentadecano sulfonate, sodium heptadecano sulfonate and potassium toluene sulfonate. The metal salts of alkylbenzene sulphonates are a highly preferred class of sulfonate surfactant. The metal will usually be sodium or potassium with sodium being preferred. Sodium salts of alkylbenzene sulfonates have the structural formula; 0 R- -S-ONa o wherein R represents an alkyl group containing from 1 to about 20 carbon atoms. It is preferred that the alkyl group contains from about 8 to about 14 carbon atoms. The sulfonate surfactant may be a mixture of (mono) dialkylate ether disulfonates. The advantage of the disulfonate structure is that it contains two ionic charges per molecule instead of one as is the case with the alkyl sulfonate surfactants. conventional Mixtures of (mono) dialkyl ether disulfonates which are useful in the practice of this invention are commercially available from a wide variety of sources. For example, Dow Chemical sells Disulfonated alkylated diphenyl oxides DowfaxHR which are of the structural formula: R R SO, Na SQ3 a wherein r is an alkyl group that is typically -C6H3, -C10H2 ?, -C12H25 or -C16H33. Sodium mono- and di-dodecyldiphenyloxide disulfonates are sold by American Cyanamide as DPOS-45 surfactants. The alpha-olefin sulfonate surfactants which are suitable for use in this invention are commercially available from Witco and Hoechst AG.

Sulfonate surfactants that are useful in the practice of this invention include metal salts of alkyl sulfates having the structural formula ROS03X and metal salts of alkyl ether sulfates having the structural formula RO (CH2CH20) NS03X, wherein X represents a metal of the Group IA, such as sodium or potassium. Sodium lauryl sulfate, sodium lauryl sulfate ethanolamine and triethanolamine lauryl sulfate are representative examples of commercially available sulfate p surfactants. The dispersants used in the polymerizations of this invention are usually condensation products of aromatic formaldehyde or polycarboxylates. The condensation products of aromatic formaldehyde are usually polysulphates which are the reaction product of aromatic compounds and formaldehyde. These soaps of aromatic formaldehyde condensation product can be made by a relatively simple process. For example, in said process, 200 parts of naphthalene are reacted with 200 parts of 98 percent sulfuric acid for 5 hours at a temperature of about 165OC. The solution then made is subsequently cooled and diluted with 90 parts of water. Then, 107 parts of a 30 percent formaldehyde solution are added and the mixture is stirred for 20 hours at a temperature of about 80aC. Towards the end of this reaction period, the mixture is gradually heated to 100aC. The neutralization is carried out subsequently at from 20aC to 25aC with about 165 to 180 parts of a 25 percent ammonia solution. The neutralization product is then filtered and, if necessary, dried in a vacuum dryer. Numerous variations of this synthesis are possible and a wide range of aromatic compounds and their derivatives can react with aldehydes, ketones and compounds that eliminate the aldehyde groups; for example, (a) dispersants produced by condensation of aromatic sulfonic acids and benzyl chloride or benzoin; (b) dispersants produced by condensation of various alkylarylsulphonic acids with a halogen arylsulphonic acid; (c) dispersants produced by condensation of phenols sulfonates or 2-naphthols with formaldehyde and various nitrogen compounds. Some representative examples of aromatic formaldehyde condensation products are shown in U.S. Patent 5,674,933, the teachings of which are incorporated herein by reference in their entirety. The carboxylate is also a water-soluble polymorphic dispersing agent. for example, methacrylic acid can be polymerized to provide water-soluble homopolymer that can be employed as a carboxylate dispersant. Copolymers with maleic acid, acrylic acid-maleic acid, methyl-maleic acid ether of maleic acid and diisobutyl-maleic acid-maleic acid (DIBMA) are also very useful in the practice of this invention. The carboxylate dispersants are commercially available from a variety of sources. In the first step of the process of this invention, (a) butylacrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) monomer of acrylonitrile, (d) a crosslinking agent, (e) a sulfonate surfactant, (f) a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates, (g) water and (h) a free radical generator is charged to a first polymerization zone. The first polymerization zone will typically be a polymerization reactor that is capable of providing temperature control and stirring. The monomer mixture charged to the first polymerization zone will typically contain from about 40 to about 90 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 weight percent acrylate. 2-ethylhexyl, from about 5 to about 35 weight percent methyl methacrylate, ethyl methacrylate, methyl acrylate or ethyl acrylate, from about 2 to about 30 weight percent acrylonitrile and about 0.25 weight percent to 6 weight percent of the crosslinking agent. Typically it is preferred that the monomer mixture charged in the first polymerization zone to include about 50 weight percent to about 85 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 percent 2-ethylhexyl acrylate, from about 5 weight percent to about 30 weight percent ethyl acrylate, ethyl methacrylate, methyl acrylate or methyl methacrylate, from about 4 weight percent to about 28 weight percent by weight of acrylonitrile and from about 0.5 weight percent to about 4 weight percent of the crosslinking agent It is generally more preferred that the monomer mixture charged to the first polymerization zone contains from about 60 weight percent to about 80 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 percent of 2-ethylhexyl acrylate, from about 5 weight percent to about 25 weight percent methacrylate, ethyl methacrylate, methyl acrylate or ethyl acrylate, from about 5 weight percent to about 25 weight percent. percent by weight of acrylonitrile and from about 1 to about 3 weight percent of crosslinking agent. In the second step of the process of this invention, the onomers charged to the first polymerization zone are allowed to polymerize at a conversion of at least about 80 percent. It is preferred that the monomer conversion achieved in the first polymerization zone is at least about 90 percent, with it being more preferred that the conversion of monomer reached in the first polymerization zone be at least about 95 percent. It is critical to limit the solids content of the latex made in the first reaction zone to a maximum of about 10 percent. In most cases, the solids content of the latex leaving the first reaction zone will be within the range of about 2 percent to about 10 percent. It is usually preferred to limit the solids content of the latex made in the first reaction zone to a maximum of about 9 percent. In most cases, it is preferred that the solids content of the latex leaving the first reaction zone be within the range of about 5 percent to about 9 percent. It is usually more preferred to limit the solids content of the latex made in the first reaction zone to a maximum of about 8 percent. In most cases, it is preferred that the solids content of the latex leaving the first reaction zone is within the range of about 6 percent to about 8 percent. In this way, the polymerization that occurs in the first polymerization zone results in the formation of a low solids polymerization medium. The free radical emulsion polymerization carried out in the first polymerization zone will typically be conducted at a temperature that is within the range of about 10aC to about 95aC. In most cases, the polymerization temperature in the first polymerization zone will be within the range of about 20aC to about 80aC. Typically it is more preferred that the temperature in the first polymerization zone be within the range of about 40 ° C to 60 ° C. In the third step of the process of this invention, the low solids polymerization medium and a mixture of (a) butyl acrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile monomer and (d) a crosslinking agent is charged to a second polymerization zone. The second polymerization zone (second reactor) will typically be similar or identical in design to the first polymerization zone (first reactor). The monomer mixture charged to the second polymerization zone will typically be of similar or identical composition to the charged monomer mixture in the first polymerization zone. In the fourth step of the process of this invention, monomers charged to the second polymerization zone are allowed to polymerize at a conversion of at least about 80 percent. It is preferred that the monomer conversion achieved in the second polymerization zone be at least about 90 percent, with it being more preferred that the monomer conversion achieved in the second polymerization zone be at least about 95 percent. It is critical to limit the solids content of the latex made in the second reaction zone to a maximum of about 20 percent. In most cases, the solids content of the latex leaving the second reaction zone will be within the range of about 6 percent to about 20 percent. It is usually preferred to limit the solids content of the latex made in the second reaction zone to a maximum of about 19 percent. In most cases, it is preferred that the solids content of the latex leaving the second reaction zone be within the range of about 12 percent to about 19 percent. It is usually more preferred to limit the solids content of the latex made in the second reaction zone to a maximum of about 18 percent. In most cases, it is preferred that the solids content of the latex leaving the second reaction zone be within the range of about 14 percent to about 18 percent. In this way, the polymerization that occurs in the second polymerization zone results in the formation of a medium solids polymerization medium. The free radical emulsion polymerization carried out in the second polymerization zone will typically be conducted at a temperature that is within the range of about 15eC to about 100aC. In most cases, the polymerization temperature in the second polymerization zone will be within the range of about 25BC to about 85aC. Typically it is more preferred that the temperature in the second polymerization zone be within the range of about 45aC to 65aC. In the fifth step of the process of this invention, the polymerization medium of intermediate solids and a mixture of (a) butyl acrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile monomer and (d) a crosslinking agent are charged to a third polymerization zone. The third polymerization zone will typically be a polymerization reactor that is capable of providing temperature control and agitation. The third polymerization zone (third reactor) will typically be similar or identical in design to the first polymerization zone (first reactor) and the second polymerization zone (second reactor). The monomer mixture charged to the third polymerization zone will typically be of similar or identical composition to the monomer mixture charged to the first and second polymerization zones. In the sixth step of the process of this invention, the monomers charged to the third polymerization zone are allowed to polymerize until a conversion of at least about 80 percent is preferred that the monomer conversion reached in the third polymerization zone be at least about of 90 percent, it being more preferred that the monomer conversion reached in the third polymerization zone be at least about 95 percent. It is critical to limit the solids content of the latex made in the third reaction zone to a maximum of about 30 percent. In most cases, the solids content of the latex leaving the third reaction zone will be within the range of about 12 percent to about 30 percent. It is usually preferred to limit the solids content of the latex made in the third reaction zone to a maximum of about 28 percent. In most cases it is preferred that the solids content of the latex leaving the third reaction zone be within the range of about 20 percent to about 28 percent. It is usually more preferred to limit the solids content of the latex made in the third reaction zone to a maximum of about 26 percent. In most cases, it is more preferred that the solids content of the latex leaving the third reaction zone be within the range of about 22 percent to about 26 percent. In this way, the polymerization that occurs in the third polymerization zone results in the formation of a polymerization medium of high solids. The free radical emulsion polymerization carried out in the third polymerization zone will typically be conducted at a temperature that is within the range of about 20aC to about 100aC. In most cases, the polymerization temperature in the third polymerization zone will be within the range of about 30aC to about 90aC. Typically it is more preferred that the temperature in the third polymerization zone be within the range of about 50aC to 70aC. In the seventh step of the process of this invention, the polymerization medium of high solids, styrene monomer, additional acrylonitrile monomer and additional crosslinking agent are charged to a fourth polymerization zone. As a general rule, from about 4 parts by weight to about 30 parts by weight of styrene, from about 1 part by weight to about 20 parts by weight of additional acrylonitrile and from about 0.01 to 2 parts by weight of the crosslinking agent will be added In this second stage of the polymerization, it is preferred to add from about 6 parts by weight to about 22 parts by weight of styrene, of about 3 parts by weight of about 12 parts by weight of acrylonitrile and of about 0.05 parts by weight to 1 part by weight of the crosslinking agent. Typically more than about 10 parts by weight to about 17 parts by weight of styrene, from about 4 parts by weight to about 8 parts by weight of acrylonitrile and from about 0.1 part by weight to about 0.5 parts by weight of the crosslinking agent to be added to the polymerization medium of high solids to initiate the second phase of the polymerization. The free radical emulsion polymerization carried out in the fourth polymerization zone, as the second polymerization stage, will typically be conducted at a temperature that is within the range of about 25aC to about 100aC. In most cases, the polymerization temperature in the fourth polymerization zone will be within the range of about 35HC to about 95SC. Typically it is more preferred that the temperature in the first polymerization zone be within the range of about 60aC to 80aC. It will generally be advantageous to carry out the second polymerization step in a series of two or more reactors. By using multiple reactors to carry out the second polymerization step, higher conversions and lower residual monomer contents can be achieved. It is particularly useful to increase the temperature slightly from reactor to reactor in the second phase of the polymerization. In any case, a final monomer conversion of at least about 90 percent and preferably at least 95 percent will be achieved. It is more preferred that the final monomer conversion be at least about 99 percent. After the polymerization is complete, it is usually desirable to add an aminoalcohol to the emulsion to deodorize the latex. The aminoalcohol will generally have the structural formula HO-A-NH2 wherein A represents an alkylene group containing from 2 to about 20 carbon atoms. It is usually preferred that the amino alcohol contains from 2 to about 10 carbon atoms with aminoalcohols, which contain from 2 to about 5 carbon atoms being more preferred, ethanolamine (HO-CH 2 -CH 2 -NH 2) which is also known as 2- Aminoethanol and 2-hydroxyethylamine is a representative example of a highly preferred amino alcohol. Some additional examples of preferred amino alcohols with 3-aminopropanol, 4-aminobutanol, 2-amino-2-methyl-l-propanol, 2-amino-2-ethyl-l, 3-propanediol, N-methyl-2,2-iminoethanol and 5-aminopentanol. This deodorization step will be carried out under conditions which allow the aminoalcohol to react with residual n-butylacrylate and acrylonitrile which is present in the emulsion. This reaction will proceed through a wide temperature range and the deodorization step can be conducted at any temperature that is within the range of about 5BC and about 952C. However, for practical reasons, the deodorization step will normally be carried out at a temperature that is within the range of about 20aC to about 70aC. Since the reaction is faster at higher temperatures, the amount of reaction time necessary will decrease with increasing temperature. For example, at a temperature of about 20 ° C, a residence time in the deodorization step of one to three days may be required. On the other hand, at a temperature of about 65 ° C, only about two hours of reaction time is normally required. The amount of time required for the aminoalcohol to react with the residual n-butylacrylate monomer and the residual acrylonitrile monomer will also depend on the level of aminoalcohol used. As a general rule, from about 0.05 weight percent to about 2 weight percent of the amino alcohol will be added based on the total weight of the emulsion. More typically, from about 0.1 weight percent to about 1.5 weight percent of the aminoalcohol will be added. It is usually preferred to use from about 0.3 weight percent to about 1 weight percent of the amino alcohol. The rubbery polymer made by the continuous polymerization process of this invention is recovered from the emulsion (latex) after the optional deodorization step. This can be achieved using conventional coagulation techniques. for example, coagulation can be achieved by the addition of salts, acids or both to the latex. After the rubbery polymer is recovered by coagulation, it can be washed to further reduce odors. This can be achieved by simply pouring or spraying water on the rubbery polymer. The rubbery polymer can also be washed by placing it in a water bath that will further reduce the odor. After washing, the rubbery polymer generally dries. Sometimes it is advantageous to convert the dry rubbery polymer into a powder to facilitate its use. In this case, it will be beneficial to add a dividing agent to the rubbery polymer. Some representative examples of cleavage agents that can be employed include calcium carbonate, polyvinyl chloride emulsion and silica. Calcium carbonate is a highly desirable splitting agent that can be used in such applications. The rubbery polymers made by the process of this invention can be mixed with polyvinyl chloride to make leather-like compositions. These skin-like compositions offer an excellent combination of properties for use in making skin compounds for panels used in automotive applications. These skin type compositions can be prepared by mixing the rubbery polymer in polyvinyl chloride (PVC), using conventional mixing techniques. It is highly preferred that the rubbery polymer be in powdered form when mixed in PVC to make such skin type compositions. A wide variety of plasticizers can be used that are compatible with polyvinyl chloride resins. Some representative examples of plastifiants that are highly suitable for this application include abietic derivatives. such as hydroabiethyl alcohol, methyl abietate and hydrogenated methyl abietate; acetic acid derivatives, such as cumylphenyl acetate; adipic acid derivatives, such as benzyloctyl adipate, dibutyl adipate, diisobutyl adipate, di- (2-ethylhexyl) adipate, diisononyl adipate, diisooctyl adipate, dinonyl adipate, linear adipate of C7-9, adipate dicapril, octyldecyl adipate (n-octyl adipate, n-decyl), straight chain alcohol adipate, dikecyl adipate (diisodecyl adipate), dibutoxyethyl adipate, high molecular weight adipate, polypropylene adipate, polypropylene adipate modified; acelaic acid derivatives, such as dicyclohexyl acelate, di- (2-ethylhexyl) acelate, di-n-hexyl acelate, low temperature plasticizer, diisooctyl acelate; benzoic acid derivatives such as diethylene glycol dibenzoate, dipropylene glycol dibenzoate, diethylene glycol benzoate and mixture of dipropylene glycol benzoate, proprietary low stain, neopentyl glycol dibenzoate, glyceryl tribenzoate, thymoliloletane tribenzoate, pentaerythritol tribenzoate, cumylphenylbenzoate; polyphenyl derivatives such as hydrogenated terphenyl; citric acid derivatives, such as triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, tributyl acetal citrate; epoxy derivatives such as butyl epoxy stearate, epoxy type plasticizer, epoxy type plasticizer talate. epoxy alkyl stearate, epoxidized butyl ester, epoxidized octyl talate, epoxidized soy bean oil, epoxidized triglycoride, epoxidized soybean oil, epoxidized sunflower oil, epoxidized type plastiZer, epoxidized linseed oil, epoxidized talate ester, 2-ethylhexyl-2-polyoxylate, octyl-epoxy stearate; proprietary esters such as proprietary ester and mixed ester; ether derivatives, such as cumylphenylbenzyl ether; formal derivatives such as butyl carbitol formal; fumaric acid derivatives, such as dibutyl fumarate, diisooctyl fumarate, dioctyl fumarate; glutaric acid derivatives such as dialkyl glutarates and mixed dicumylphenyl glutarate; glycol derivatives such as diethylene glycol dipelargonate, triethylene glycol dipelargonate, triethylene glycol di- (2-ylbutyrate), triethylene glycol di-caprylate-triethylene glycol di-82-ethylhexoate, triethylene glycol dicaprylate, tetraethylene glycol dicaprylate, (2-ethylhexoate) of polyethylene glycol, butyl phthalyl butylglucolate, fatty acid triglycol ester of vegetable oil, triethylene glycol fatty acid ester; linear dibasic acid derivatives such as mixed dibasic ester; petroleum derivatives * such as aromatic hydrocarbons; isobutyric acid derivatives such as diisobut irate 2, 2, 4-trimethyl-l, 3-pentanediol; isophthalic acid derivatives such as di (2-ethylhexyl) isophthalate, diisooctyl isophthalate, dioctyl isophthalate; lauric acid derivatives such as butylurate, 1,2-propylene glycol monolaurate, tileglycol monoethyl ether laurate, ethylene glycol monobutyl ether laurate, glycerol monolaurate, polyethylene glycol-400-dilaurate; melitates such as n-octyl trimellitate, n-decyl, tri-n-octyl-n-decyl trimellitate, triisononyl trimellitate, triisooctyl trimellitate, tricapryl trimellitate, diisooctyl trimellitate monoisodecyl, triisodyl trimellitate, trimellitate tri ( C7-9 alkyl), tri-2-ethylhexyl trimellitate; nitrile derivatives such as fatty acid nitrile; oleic acid derivatives such as butyl oleate, 1,2-propylene glycol monooleate, ethylene glycol monobutyl ether oleate, tetrahydrofur furyl oleate, glyceryl monoleate; paraffin derivatives such as chlorinated paraffins, diethylene glycol dipelargonate, triethylene glycol dipelargonate, 2-butoxyethyle dipelargonate; phenoxy plastics such as acetyl paracumyl phenol; phosphoric acid derivatives such as tri (2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, cresyl-phenyl phosphate, tricresyl phosphate, tri-isopropyl phenyl phosphate, alkylaryl phosphate, di-phenyl-xylenyl phosphate, phenyl isopropyl phenyl phosphate; italic acid derivatives such as alkylbenzene phthalates, dimethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dihexyl phthalate, butyloctyl phthalate, butyl isodecyl phthalate, butyl isohexyl phthalate, diisononyl phthalate, dioctyl phthalate, phthalate of di- (2-ethylhexyl), n-octyl-n-decyl phthalate, hexyl octyl decyl phthalate, didecyl phthalate, phthalate phthalate. diisodecyl, diisodecyl phthalate, diundecyl phthalate, butyl-ethylhexyl phthalate, butylbenzyl phthalate, octylbenzyl phthalate, cyclohexyl phthalate, diphenyl phthalate, alkylaryl phthalates and 2-ethylhexylisodecyl phthalate; ricinoleic acid derivatives, such as methylacetyl ricinoleate, n-butylacetyl ricinoleate, glyceryl triacetyl ricinoleate; sebacic acid derivatives, and dibutoxyethyl sebacate; stearic acid derivatives such as glyceryl tri-acetoxy stearate, butylacetoxy stearate, methyl pentachloroetherate and methoxyethylacetoxy stearate; sucrose derivatives such as sucrose benzoate; suifonic acid derivatives such as alkylsulphonic esters of phenol; liquid resin derivatives such as liquid resin methyl ester and isooctyl ester. of liquid resin; and terephthalic acid derivatives such as dioctyl terphthalate. These skin type compositions typically contain from about 40 to 160 parts by weight of the rubbery polymer, from about 10 to about 50 parts of a plasticizer and from about 0.1 to about 5 parts by weight of an antidegradant per 100 parts by weight of polyvinyl chloride. It is typically preferred that said skin-type compositions contain from about 60 to about 120 parts by weight of the rubbery polymer, from about 15 to about 40 parts of the plasticizer and from about 0.5 to 3 parts of an antidegradant (per 100 parts of the PVC). Typically it is more preferred that the skin type composition contains from about 70 to about 90 parts by weight of the rubbery polymer, from about 20 to about 30 parts by weight of the plasticizer and from about 1 to 2 parts by weight of the antidegradant by 100 parts by weight of PVC. These compositions will also generally contain an acrylonitrile-trilo-butadiene-styrene resin (ABS resin). The skin type composition will typically contain from about 15 parts to about 80 parts of ABS resin per 100 parts of PVC. The The skin type composition will preferably contain from about 25 to about 55 parts by weight of the ABS resin per 100 parts by weight of the PVC. It is generally more preferable that the skin type composition contains from about 30 to about 40 parts by weight of the ABS resin per 100 parts by weight of PVC. Various dyes and / or pigments will typically be added to the composition to achieve a desired color. These skin-like compositions are useful in a wide variety of applications. For example, they have been found to be extremely valuable when used when making skins for automotive panels. These panels are typically comprised of a semi-rigid urethane foam that is supported by a rigid backing and covered with the skin-like composition of this invention. These skins are made by calendering the skin compositions of this invention and then cutting them to the desired size and shape. These skins for automotive applications that are made with the skin-like compositions of this invention offer surprising stability to heat and ultraviolet light. These are highly desirable features that can help prevent the skin of automotive panels from cracking during the normal life of the vehicle. The rubbery polymers made by the continuous process of this invention can also be blended with other polymers containing halogen (in addition to PVC), styrenic polymers (styrene-containing polymers, such as acrylonitrile-styrene-acrylate (ASA) polymers, polyolefins and polyamides) to produce compositions that exhibit good resistance to heat and ultraviolet light These polymeric compositions can be used in the manufacture of a wide variety of useful articles, such as profiles, moldings, laminates, floors, wall coverings, hoses, cables and footwear. Polyamide (nylon) can be used when preparing these mixtures.

These nylons are generally prepared by reacting diamines with dicarboxylic acids. The diamines and dicarboxylic acids that are used in preparing these nylons will generally contain from about 2 to about 12 carbon atoms. However, the nylons that can be used in such mixtures can also be prepared by addition polymerization. Some representative examples of nylons that can be used include nylon-6,6, nylon-6, nylon-7, nylon-8, nylon-9, nylon-10, nylon-11, nylon-12 and nylon-6,12. These nylons will typically have a number average molecular weight that is within the range of about 8,000 to about 40,000 and more typically have a number average molecular weight that is within the range of about 10,000 to about 25,000. Some representative examples of polyolefins that may be used include linear low density polyethylene, high density polyethylene, polypropylene, polyutylene and modified polyolefins, such as ethylene vinylacetate (EVA). This invention is illustrated by the following examples which are merely for the purpose of illustration and are not to be construed as limiting the scope of this invention or the manner in which it can be practiced. Unless specifically indicated otherwise, all parts and percentages are given by weight.

Example 1 In this experiment, a rubbery polymer was made using the continuous polymerization technique of this invention. The polymerization was conducted in a series of six reactors having a capacity of 2 liters. The reactors were equipped with an axially fancy turbine agitator operated at 110 rpm (revolutions per minute). An aqueous phase buffer solution containing 201.1 phm of water, 3 phm of sodium dodecylbenzene sulfonate soap, 3.5 phm of Sokalan ™ PM 1.01 polycarboxylate soap, 0.06 phm of triethanolamine, 0.2 phm of tetrasodium pyrophosphate electrolyte and 0.08 phm of t-dodecyl mercaptan was charged to the first reactor at a rate of 12 grams per minute. An initiator solution containing 33.8 phm of water and 0.4 phm of potassium persulfate was also charged to the first reactor at the rate of 2 grams per minute. Finally, a first phase monomer solution containing 71.7 phm of n-butylacrylate, 8.4 phm of acrylonitrile, 4.2 phm of methyl methacrylate was charged to the first reactor at a rate of 1 gram per minute.

This monomeric solution was also fed separately to the second and third reactors at a rate of 1 gram per minute. In other words, the first phase monomer solution was divided into three forms and charged in equal amounts to each of the first three reactors. A temperature of 50aC was maintained in the first reactor. The latex made in the first reactor had a solids content of about 8 percent and was fed continuously into the second reactor along with the monomeric solution. A temperature of 55aC was maintained in the second reactor. The latex synthesized in the second reactor had a solids content of about 18 percent and was continuously fed into the third reactor together with the monomer solution. a temperature of 60EC was maintained in the third reactor. The latex made in the third reactor had a solids content of about 26 percent and was fed continuously into the fourth reactor. A monomeric second phase solution containing 11.2 phm of styrene, 4.8 phm of acrylonitrile, 0.18 phm of divinylbenzene and 0.03 phm of t-todecyl mercaptan was also separately charged to the fourth reactor at a rate of 1 gram per minute. The fourth reactor was maintained at a temperature of 60 ° C and the latex made therein was continuously charged to a fifth reactor which was maintained at a temperature of 70 ° C. The latex made in the fifth reactor was continuously charged to a sixth reactor which was also maintained at a temperature of 70 ° C. the latex that came out of the sixth reactor had a solids content of about 30 percent and an average particle size of about 143 nm. The made latex was subsequently coagulated and a dry rubber was recovered. The dry rubber was determined to have a Mooney viscosity ML 1 + 4 at 100aC of approximately 47, a Mooney viscosity ML 1 + 4 at 150QC of about 23 and a Haake torque (177aC / 50 rpm 20 minutes) of approximately 900 m.g. This experiment shows that the continuous process of this invention can be used to make a rubbery polymer having a small latex particle size of less than 150 nm.

Comparison Example 2 In this experiment, the procedure described in Example 1 was repeated, except that only one chain of five reactors was used. In this experiment, the monomeric first phase solution was fed only to the first two reactors at a feed rate of 1.5 grams per minute. However, the latex made using this procedure had an average particle size of more than 150 nm Comparative Example 3 In this experiment, the procedure described in Example 1 was repeated, except that a chain of only four reactors was used. In this experiment, the monomeric first phase solution was fed only to the first reactor at a feed rate of 3 grams per minute. However, the latex made using this procedure had an average particle size of about 200 nm. This experiment and Comparative Example 2 show the critical nature of dividing the first phase monomeric solution from at least three reactors to maintain a particle size. of satisfactory latex of less than 150 nm.

Example 4 The samples were made by kneading the rubbery polymer synthesized in Example 1 in two roller mills at 50aC for 6 minutes and compression molding at 150eC for 10 minutes. The physical test showed a tensile strength of 7.7 MPa, a modulus of 50 percent elongation of 2.5 MPa, an elongation at break of 415 percent and a tear strength of 25 N / m. As can be seen from Table y, these physical properties compare favorably with the physical properties of the test samples made from Sunigum (R) 7395 rubber and Sunigum (R) 7358 rubber using the same procedure.

TABLE 1 Cauchotous Polymer Sunigum "" Sunigum (R) Del. Example 7395 7558 1 Stress Resistance (MPa) 6.1 7.2 7.7 Module at 50% (MPa) 1.3 1.8 2.5 Module at 100% (MPa) 2.9 3.3 3.4 Elongation at Break (%) 320 220 415 Resistance to tearing (KN / m) 17 15 25 Example 5 A skin type composition can be made by mixing the rubbery polymer synthesized in Example 1 to PVC resin. This mixture can be prepared by mixing 100 parts of PVC resin, 40 parts of the rubbery polymer, 50 parts of a plasticizer, 3 parts of a stabilizer. This skin type composition was made by kneading the mixture in two roller mills at 180 aC for 6 minutes and then compression molding at 180 aC for 10 minutes. The physical properties of the skin type composition made were determined and compared with leather-like compositions made with Sunigum rubber "7395 and rubber.

Sunigum "7558 made using the same procedure (see Table II) TABLE II Cauigotoso Polymer Sunigum" "Sunigum (R) Axis, 7395 7558 1 Shore Hardness A 78 81 74 Resistance to Tension (MPa) 17.8 17.3 17.5 Module at 50% (MPa) 5.2 5.8 5.1 Module at 100% (MPa) 8.0 9.1 8.2 Elongation at break (%) 290 240 270 Tear Resistance (KN / m) 60 61 64 Even though certain representative embodiments and details have been shown for the purpose of illustrating the present invention, it will be evident to those experienced in this field that various changes and modifications may be made therein without giving up. the scope of the present invention.

Claims (9)

1. - A process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin type composition having good resistance to heat and ultraviolet light, the process being characterized by continuously carrying out the steps of (1) loading (a) ) butyl acrylate monomer, (b) at least one acrylate monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile monomer, (d) a crosslinking agent , (e) a sulfonate surfactant, (f) a dispersant selected from the group consisting of condensation products of aromatic formaldehyde and polycarboxylates to a first polymerization zone, (g) water, and (h) a generator of free radical; (2) allow the monomers to polymerize in the first polymerization zone under emulsion polymerization conditions to a monomer conversion of at least 80 percent to produce a low solids polymerization medium having a solids content of no more than of 10 percent; (3) charge (a) the low solids polymerization medium, (b) additional butyl acrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer and (e) additional crosslinking agent to a second polymerization zone; (4) allow the monomers to be polymerized in the second polymerization zone under emulsion polymerization conditions at a monomer conversion of at least 80 percent to produce an intermediate solid polymerization medium having a solids content of no more than of 20 percent; (5) charge (a) intermediate solid polymerization medium, (b) additional butyl acrylate monomer, (c) additional acrylate monomer, (d) additional acrylonitrile monomer, and (e) additional crosslinking agent to a third polymerization zone; (6) allow the monomers to be polymerized in the third polymerization zone under emulsion polymerization conditions at a monomer conversion of at least 80 percent to produce a high solids polymerization medium having a solids content of no more than of 30 percent; (7) loading (a) the high solids polymerization medium, (b) styrene, (c) additional acrylonitrile and (d) further crosslinking agent into a fourth polymerization zone; (i) allowing the monomers to be polymerized in the fourth polymerization zone under emulsion polymerization conditions at a monomer conversion of at least 80 percent to produce an emulsion containing the rubbery polymer; and (9) recovering the rubbery polymer from the emulsion containing the rubbery polymer.

2. A process as specified in claim 1, characterized in that an aminoalcohol is added to the emulsion containing the rubbery polymer produced in the fourth polymerization zone.

3. A process as specified in claim 1 or 2, characterized in that a monomer conversion of at least 90 percent is achieved in the polymerizations of steps (2), (4), (6) and (8) ); characterized in that the process is carried out at a temperature that is within the range of 20aC to 100aC; characterized in that the solids content achieved in step (2) is within the range of 2 percent to 10 percent; characterized in that the solids content achieved in step (4) is within the range of 6 percent to 20 percent; and characterized in that the solids content achieved in step (6) is within the range of 12 percent to 30 percent.

4. A process as specified in claim 1, 2, or 3, characterized in that (a) 40 weight percent to 80 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2- ? t -hexyl acrylate containing up to 40 weight percent of 2-ethylhexyl acrylate, (b) 5 weight percent to 35 weight percent of methyl methacrylate, ethyl methacrylate, methyl acrylate or ethyl acrylate, (c9 4 weight percent to 30 weight percent acrylonitrile and (d) 0.25 percent by weight at 8 weight percent of a crosslinking agent are loaded in steps (1), (3) and (5)

5. A process as specified in any of the preceding claims, characterized in that 50 by weight percent to 85 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to 40 percent 2-ethylhexyl acrylate, from 5 weight percent to 30 weight percent ethyl acrylate, ethyl methacrylate, methyl acrylate or methyl methacrylate, from 4 weight percent to 28 weight percent acrylonitrile and from 0.5 weight percent to 4 weight percent of the crosslinking agent loaded in steps 81) , (3) and (5); and characterized in that the temperature in the first polymerization zone is within the range of 20SC to 80aC; in "where the temperature in the second polymerization zone is within the range of 25aC to 85aC, where the temperature within the third polymerization zone is within the range of 30ac to 90aC, and where the temperature within the Fourth polymerization zone is within the range of 35aC to 95aC

6. A process as specified in any of the preceding claims, characterized in that the solids content achieved in step (2) is within the scale of 5. percent to 9 percent, where the solids content achieved in step (4) is within the range of 12 percent to 19 percent, and where the solids content achieved in step (6) is within of the scale from 20 percent to 28 percent, and characterized in that 60 weight percent to 80 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to 40 percent by weight 2-ethylhexyl acrylate, 5-fold weight percent to 25 weight percent ethyl acrylate, ethyl methacrylate, methyl acrylate or methyl methacrylate, from 5 weight percent to 25 weight percent acrylonitrile and from 1 weight percent to 3 weight percent of the crosslinking agent are charged in steps (1), (3) and (5) 7.- A process as specified in any of the preceding claims, characterized in that the temperature in the first polymerization zone is within the scale from 40HC to 60aC; wherein the temperature in the second polymerization zone is within, from the scale of 45ac to 65aC; wherein the temperature within the third polymerization zone is within the range of 50 ° C to 70 ° C; and wherein the temperature within the fourth polymerization zone is within the range of 60aC to 80aC; wherein the solids content achieved in step (2) is within the range of 6 percent to 8 percent; wherein the solids content achieved in step (4) is within the range of 14 percent to 18 percent; and wherein the solids content achieved in step (6) is within the range of 22 percent to 26 percent. 8. A process as specified in any of claims 2-7, characterized in that the aminoalcohol contains from 2 to about 20 carbon atoms; and characterized in that the aminoalcohol is allowed to react with residual acrylonitrile and residual n-butylacrylate at a temperature that is within the range of 5HC to 95aC. 9. A process as specified in any of the preceding claims, which ST characterizes by washing the rubbery polymer with water after it is recovered from the emulsion, - A process as specified in claim 9, characterized further by drying the rubbery polymer after it has been washed and subsequently converting it into a powder in the presence of a dividing agent selected from the group consisting of calcium carbonate, polyvinyl chloride emulsion and silica. SUMMARY OF THE INVENTION There is a need for polymers that are used in automotive interiors that offer increased resistance to heat and ultraviolet light. It is particularly critical for polymers that are used when making skin compounds for automotive instrument panels and doors to exhibit excellent resistance to value and ultraviolet light. This invention describes a continuous process for preparing a rubbery polymer that can be mixed with polyvinyl chloride to make skin-like compositions having good resistance to heat and ultraviolet light. This technique involves using a system of multiple continuous reactors wherein a first phase monomer solution containing butyl acrylate, an acrylic monomer, acrylonitrile and a crosslinking agent is continuously charged to at least three initial reactors. To achieve a small particle size, it is necessary to limit the solids content in each of these initial reactors. Then, a second phase monomer solution containing styrene, additional acrylonitrile and additional crosslinking agent is continuously charged to a subsequent reactor. This technique can also be used to synthesize core / shell structures or IPN using multistage emulsion polymerization in which the first stage latex contains a majority of butyl acrylate with a small latex particle size being obtained.