IL44184A - Fire retardant thermoplastic interpolymer concentrate - Google Patents

Description

A fire retardant thermoplastic interpolymer concentrate - - A FIRE RE ARDANT THERMOPLASTIC INTERPOLYMER CONCENTRATE ABSTRACT OF THE DISCLOSURE This invention relates to a fire retardant interpolymer conoentrate comprising chloroprene rubber interpolymerlzed with a monovinylidene aromatic hydrocarbon monomer and an ethylenlcally unsaturated nltrile monomer to form a grafted chloroprene rubber interpolymer concentrate, the novel grafted chloroprene rubber interpolymer concentrate when provi di ng polyblended with a styrene polymer -rovides the styrene 1 servi ng polymer with high impact strength and also selves as a source of halogen for flame retardancy.

IRv-en-tGF*-:---G-avy--Lee--Bee&s Rob«rt-Loul4s—Kru&e- 08-12-0236A A FIRE RETARDANT THERMOPLASTIC INTERPOLYMER CONCENTRATE This invention relates to a fire retardant grafted rubber interpolymer concentrate composition for polymeric polyblends comprising a grafted chloroprene rubber and a polymer of at least one monovinylidene hydrocarbon monomer and 0-90? by weight of an ethylenically unsaturated nitrile monomer, the chloroprene rubber being grafted with said monomers. The interpolymer concentrate when polyblended with styrene polymers provides the styrene polymer with high impact strength and fire retardancy. A metal compound can be optionally added to the polyblend to provide self-extinguishing properties to the polyblend.

Polymeric materials of the styrene family including polystyrene and its copolymers, impact resistant polystyrene containing dispersed rubber phases as polyblends and more recently impact resistant copolymers and terpolymers of styrene have gained great commercial utility as tough engineering plastics. Such plastics appear as structural parts of appliances, automobiles and housing.

Government codes are requiring that such plastics be flame-retarding and self-extinguishing. The industry has developed many improved grades of such materials, however, with the ever greater need for high performance plastics, most self-extinguishing types have suffered from inadequate physical properties such as toughness and impact strength. 1 Self-extinguishing plastics have been formulated with various additives which when added in sufficient amount to roduce self-extin uishin ro erties in the ol mer cause t e 08-12-0236A materials such as the halogenated aliphatic and aromatic compounds which are compatible with the styrene polymer family of plastics often act as plasticizers and lower the modulus, reducing the tensile strength.

Certain inorganic compounds, in particular metal oxide compounds when used in combination with the halogenated organic compound, appear to catalyze their decomposition or enter the chain of reactions to form metal halides that are effective flame retardants. Such systems are not predictable in that many such combinations lower the melt point of the polymer causing it to pyrolyze more readily, hence actually increasing flammability . Beyond flammability such combinations have caused the polymer systems to degrade during heat processing or on exposure to light.

Polymeric plasticizers containing halogens such as poly-vinyl chloride and chlorinated olefins have been tried to overcome the deficiencies of the lower molecular weight halogenated organic compounds. Such polymeric materials, however, as used in the styrene family of plastics have lowered their heat stability during processing and given lower physical properties particularly lower modulus, heat distortion and impact strength. The term "modul us " refers both to tensi l e and flexural modul i .

The above problems can be overcome in the styrene family of impact polymeric polyblends by incorporating a particular novel fire retardant grafted chloroprene rubber interpolymer concentrate o the present invention that will provide both fire retardant properties and superior physical properties such as impact strength and toughness. It has also been - - metal oxides in the polyblends can provide self-extinguishing properties to the polyblend.

Hence, the fire retardant grafted rubber interpolymer concentrates of the present invention have great utility in the manufacture of polyblends. Polymer processors can polymerize or buy the rigid styrene polymers; polymerize the fire retardant interpolymer concentrate of the present invention and compound tough self-extinguishing polyblends giving the compounding processor great freedom of operation.

The grafted chloroprene rubber interpolymer concentrate of the present invention is a product of polymerization wherein the monomers are interpolymerized in the presence of chloroprene rubber with the monomers grafting onto the rubber and also polymerizing to form polymers of said monomers. The level of grafting can be controlled with the rubber being grafted 10% to 100? by weight with said monomers based on the weight of the rubber with the percent of polymer formed being varied generally from 1% to 82% of said interpoly mer. The term grafted rubber interpolymer concentrate is by definition an interpolymer comprising ε high percentage of rubber in the interpolymer generally 15% to 75% by weight preferably ^O to 60?. Said concentrates may have present other additives such as coloring dyes and pigments, antioxidants, UV absorbers, fillers, lubricants, plasticizers , fibers e.g., as disclosed such concentrates can be polyblended with brittle styrene polymers to improve their toughness and other physical properties .

- - The grafted chloroprene rubber interpolymer concentrates of the present Invention have great Intrinsic utility beyond their use In polyblends. The polymerization products of rubbers with monomers are generally recovered from polymeriza-tion processes by coagulation, filtering, washing and drying.

In such processes the Interpolymer Is generally In a finely divided state with large surface areas to aid In drying.

However, such lnterpolymers of the butadiene rubber type are highly Inflammable In the usual rotary or fluid bed drier.

It has been discovered that the grafted polychloroprene Interpolymer concentrate of the present Invention Is fire retardant and does not readily support combustion making such concentrates much safer to dry, handle, process and store.

The grafted chloroprene interpolymer concentrates have also been found to have antistatic properties that provide safety and ease of handling through driers and material handling systems . The chances of explosion is reduced because the concentrate particles do not develop high electro-static charges which can discharge causing explosions and fires in processing finely divided rubber particles such as the butadiene rubber types.

SUMMARY OP THE INVENTION The present invention relates to a fire retardant thermoplastic interpolymer concentrate for polymeric polyblends, said interpolymer concentrate composition comprising: - - (A) Prom 1% to 82* by weight of a polymer of at least one monovinylidene aromatic hydrocarbon monomer and an ethylenically unsaturated nitrlle monomer wherein said ethylenically unsaturated nitrile monomer moiety constitutes from 0% to 90% by weight of the said polymer, and (B) from M to 99% by weight of a grafted chloroprene rubber copolymer said rubber grafted with: (1) at least one monovinylidene aromatic hydrocarbon monomer, and ] (2) an ethylenically unsaturated nitrile monomer wherein said ethylenically unsaturated nitrile monomer moiety constitutes from 0% to 90% by weight of the total monomers grafted, wherein a chloroprene rubber moiety is present in from 15Ϊ to 75% by weight of the interpolymer concentrate with polymer (A) and copolymer (B) obtained as said interpolymer concentrate by the polymerization of at least one of said monomers in the presence of said chloroprene rubber.

As employed herein, the term polyblend means a mechanical mixture of incompatible polymers wherein the mixing is carried out in the melt phase with one polymer phase being 08-12-0236A The grafted chloroprene rubber Interpolymer concentrate of the present invention can be dispersed or polyblended Into the polystyrene or polystyrene copolymer phase by the conventional melt working of a mechanical mixture of the two. Melt working and mixing is conventionally carried out, by those skilled in the art, through extrusion, milling or banburying, for example wherein the styrene polymer phase reaches a melt temperature of 20Ί to 232°c. Other additives may be present in the melt, e.g. anti-oxidants , lubricants and pigments.

Such polystyrene polyblends have the rigidity and modulus of the outer polystyrene or polystyrene copolymer phase. The inner grafted chloroprene rubber phase exists as small rubber particles that provide the polyblend with much higher impact strength than the rigid outer polymeric phase can provide as a single phase. Such rubber particles are considered to be stress relieving centers that give the polyblend high Impact strength, greater elongation at fail under stress and greater toughness without serious loss of modulus or rigidity in the outer phase.

The self-extinguishing grafted chloroprene rubber interpolymer concentrate of the present invention is a product of polymerization wherein at least one monovinylidene aromatic monomer and/or ethylenically unsaturated nitrile monomers are polymerized In the presence of chloroprene rubber. The polymerization reaction causes the monomers to polymerize as homopolymer or copolymer and as homopolymer or copolymer chains attached to the rubber molecule forming a grafted polychloro-prene rubber interpolymer concentrate.

The monovinylidene aromatic monomers used in the polymers making up the concentrates of this invention include styrene, aralkylstyrenes, e.g. o-, m-, and p-methylstyrenes, -ethylstyrenes, -isopropylstyrenes , -butylstyrenes , -tertiary butylstyrenes, various alphalkylstyrenes , e.g. methylstyrenes , ethylstyrenes, various arhalostyrenes, e.g. o-, m-, and p-chlorpstyrenes , bromostyrenes, fluorostyrenes ; various di, tri, tetra and penta substituted chlorostyrenes , bromostyrenes and fluorostyrenes and various alpha- and beta-halosubstituted styrenes, e.g. alphachlorostyrenes , alphabromostyrenes, beta halo-substituted and the like.

The ethylenically unsaturated nitrile monomers used in the interpolymer concentrates are, e.g. acrylonitrile, methacrylonltrlle, ethacrylonltrlle, methyl methacrylonltrlle and the like with acrylonitrile and methacrylonltrlle and the like being preferred.

Either of the vinylidene aromatic monomer or the ethylen-' ically unsaturated nitrile monomer can be used in major proportions relative to one another in copolymerlzatlon or grafting.

For example, styrene and acrylonitrile will copolymerize with the preferred ratio of styrene to acrylonitrile (S/AN) being about 755K S to 25% AN or the azeo-tropic mixture of the two which gives a uniform copolymer. These ratios can be varied from 95/1 to 1/95 » S/AN, with certain polymerization methods to give polymers that have great utility.

In applications that need properties such as gas impermeability, light stability, toughness, etc., it is preferred to have the nitrile monomer present in greater proportions, 08-12-0236A the fabricated part needs greater plasticity, composition containing a major portion of the monovinylidene aromatic monomer is preferred, e.g. up to 90 weight percent. The monovinyl aromatic monomer may be halogensubstltuted providing a halogen source for flame retarding and can be used in major proportions in the present invention, e.g. 20 to 80 weight percent.

The rubber component of the interpolymer concentrate may be polychloroprene or copolymers of chloroprene and other monomers,e.g. butadiene, acrylonitrile , methacrylonitrile, styrene, arhalostyrene, alphahalostyrenes, aralkylstyrenes , alphalkylstyrenes, vinyl chloride; or mixtures of polychloroprene and other synthetic or natural rubbers, e.g. poly-butadiene, butadiene-styrene copolymer, isoprene, nitrile rubbers, acrylate rubber, butadiene-styrene-acrylonitrile terpolymers, chloroprene-butadiene-styrene terpolymers, chloroprene-butadiene-acrylonitrile terpolymers, halogenated rubbers and the like.

Other monomers may be interpolymerized with the mono-vinylidene-aromatic monomers and the ethylenlcally unsaturated nitriles of the interpolymer concentrate phase already described. The described monomers can be replaced by such other monomers, e.g. 1 to 25% by weight, consistent with maintaining the properties of the polyblend as already described. Exemplary of such other monomers are conjugated 1,3 dienes, e.g. butadiene, isoprene, etc.; alpha- or beta-unsaturated monobasic acids or derivatives thereof, e.g. acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, - - 2-ethylhexyl aer late, methacrylic acid and the corresponding esters thereof; acrylamide, methacrylamidej vinylidene chloride, vinylidene bromide, etc.: vinyl esters such as vinyl acetate, vinyl propionate, etc., dlalkyl maleates or fumarates such as dimethyl maleate, diethyl maleate, dibutyl maleate, the corresponding fumarates, etc. The above described other monomers may also be interpolymerized with chloroprene of the rubber phase either as comonomers or grafted monomers on the poly-chloroprene rubber.

Chloroprene rubbers are commercially available as solid rubbers or rubbers contained in emulsions . The generally preferred solid rubbers are of the type containing no antioxidant, are colorlees, have good heat stability for processing and are soluble or dispersible in the monovinylidene aromatic and ethylenically unsaturated nitrile monomers either in combination or singly. A polymerizing mixture of polychloroprene, styrene and acrylonltrile, etc., wherein the rubber is in solution or dispersed in the reacting monomers will polymerize causing the monomers to graft onto the polychloroprene rubber molecules as grafted chains to form an interpolymer or grafted chloroprene rubber. As the polymerization progresses a copolymer of styrene and acrylonltrile (SAN) is also formed in the reacting mixture. As the SAN phase becomes larger than the grafted phase the rubber phase will invert to become the internal phase as a dispersed grafted rubber particle in SAN. Under agitation this dispersion becomes a uniform dispersion of grafted chloroprene rubber in SAN polymer forming a grafted chloroprene interpolymer concentrate. 08-12-0236A chloroprene provides the novel combination of not only Improving the Impact strength of the larger SAN phase but also causing the SAN polymers to be flame retardant and self-extinguishing .

The chloroprene rubbers contained in emulsion are readily grafted by dispersing the reacting monomers in the emulsion and grafting such monomers to the rubber much as in the case of the solution polymerization system.

The percent graft is a controlled amount and can be varied from about 10 to 10056 depending on the weight average particle size of the rubber and the properties desired. percent The preoent graft is defined as the weight percent of monomers grafted to the rubber particle based on the weight of the rubber, e.g. 100 grams of rubber grafted with 100 grams of monomers has 10056 by weight of grafted monomers .

The weight average particle size of the rubber is selected to provide a balance of good physical properties such as impact strength and gloss. In the emulsion polymerization systems the rubber particle size ranges from 0.01 to 0.35 microns with about 0.05 to 0.20 microns being most preferred to give the polyblend desirable impact strength and high gloss. Being small in particle size they do not lower molded surface gloss. This size rubber particle Is grafted in a range of 10 to 100 by weight with ^5 to 65% being most preferred to insure compatibility and insure good gloss.

A larger weight average rubber particle size ranging from O. O to 1.5 microns and preferably from 0.50 to 1.0 microns is polyblended with the small rubber particles to further 08-12-0236A increase the impact strength. The larger rubber particle is grafted in the range from 5* to 0 by weight with 10* to 30% being most preferred to insure compatibility and maintain the integrity and particularity of the rubber particle.

Generally, the polyblends made from the concentrate have from 50* to 9756 by weight, preferably from 70 to 90* by weight, of the total weight of the grafted rubber, in the polyblend, in the form of smaller grafted rubber particles and correspondingly from 3% to 50* by weight, preferably from 10% to 30%, of the larger grafted rubber particles insuring a balance of good gloss and impact strength.

The polyblends made from the concentrate require from 15 to l\0% by weight, of chloroprene rubber based on the total polyblend to insure self-extinguishing properties for the combination. The grafted rubber must be present, in the polyblend, In an amount of from 16.5% to 80* by weight, preferably from 16.5% to 70%, of the polyblend considering that the graft level can be from about 10* to 100* by weight of the chloroprene rubber.

Polyblends using grafted chloroprene rubber concentrate may also be prepared having good gloss and impact strength by selecting an optimum single mode weight average grafted rubber particle size rather than a polymode of small and large rubber particles. This can be accomplished by selec-ting rubber particles having a weight average particle size of about 0. to 1.0 microns, preferably from 0.5 to 0.8 microns, and grafting to a higher level ranging from 10 to 100* and most preferably from 15* to 65* by weight based on rubber. 0 -12-023 A A further refinement of the polyblend system is used to insure good physical properties such as gloss and impact strength. The degree of graft stabilizes the rubber particle insuring its particulate character so that It stays dispersed in the polyblend and does not agglomerate under the heat and shear of melt colloiding and processing. The chloroprene rubber is preferably chemically crossllnked to further maintain this particulate property. The most preferred chloroprene rubbers used in the emulsion graft systems are crossllnked and contain a medium to high gel content being extremely viscous having a Mooney viscosity above at least 200 (MS 2-1/2 min. 100°C). These rubber latices are commercially available.

It has been further discovered that grafted chloroprene rubber interpolymer concentrates can have their physical properties further enhanced by blending in small amounts of grafted polybutadlene rubbers to increase low temperature impact properties. Chloroprene rubbers have a second order transition temperature (Tg by ASTM Test D-7 6-52T) of about - 0°C. and become brittle as this temperature is approached In use. The polyblends lose Impact strength as the polyblend reaches this temperature range because the grafted rubber particles of the polyblend become brittle can no longer absorb stress. Polybutadlene rubbers have a lower Tg, in particular, the high cis-type polybutadlene rubbers have a Tg range of from about -50 to -105°C. with a preferred range of from about -75° to -95°C. Such rubbers are grafted with monovinylidene aromatic monomers (e.g. styrene) and/or ethylenically unsaturated nitrile monomers, e.g. acrylonitrile or methacrylonitrile and 08-12-0236A It has been discovered that a small amount of grafted crossllnklng polybutadlene rubber wherein the rubber Is grafted with 50 to 150% by weight of said monomers and provides 5.0* to 0% , preferably 10 to 30ί, by weight of rubber to the total concentrate giving an impact strength of 8.2 to 38.2 Kg cm/cm notch when blended with the grafted polychloroprene Interpolymer polyblend having a highly grafted chloroprene rubber with a small particle size. The grafted polybutadlene rubber particle generally has a weight average size of from about 0.7 to Ί.0 microns, preferably from 0.8 to 1.2 microns, wherein the polychloroprene rubber particle has a weight average size of from .01 to 0.35 microns. Such blends have a high gloss, in the range of 50 to 70 by the Hunter Gloss Meter.

In preparing self-extinguishing polyblends it is necessary to have present in the polyblend at least about 1% by weight of the polyblend of an inorganic compound and generally not more than 15%» the preferred amount ranjcine from 5% to 10%.

The inorganic compounds preferred are certain metal oxides, e.g. Sb20g, Β^Ο^» MoO^, Sn02, WO^, and the like.

The most preferred being Sb20g.

The following examples are presented in illustration of the present invention and are not intended in any way to limit the scope or spirit thereof.

TEST PROCEDURES Underwriter's Laboratory Subject No. 91* Test Self-extinguishing (S.E.) properties were measured 08-12-0236A The test specimen is supported from the upper end, with longest dimension vertical, by a clamp on a ring stand so that the lower end of the specimen is 0.^5 cm above the top of the burner tube. The burner is then placed remote from the sample, ignited, and adjusted to produce a blue flame 1.9 cm in height.

The test flame is placed centrally under the lower end of the test specimen and allowed to remain for 10 seconds.

The test flame is then withdrawn, and the duration of flaming or glowing combustion of the specimen noted. If flaming or glowing combustion of the specimen ceases within 30 seconds after removal of the test flame, the test flame is again placed under the specimen for 10 seconds immediately after flaming or glowing combustion of the specimen stops. The test flame is again withdrawn, and the duration of flaming or glowing combustion of the specimen noted.

If the specimen drips flaming particles or droplets while burning in this test, these drippings shall be allowed to fall onto a horizontal layer of cotton fibers (untreated surgical cotton) placed one foot below the test specimen.

Significantly flaming particles are considered to be those capable of igniting the cotton fibers.

The duration of flaming or glowing combustion of vertical specimens after application of the test flame, average of three specimens (6 flame applications) shall not exceed 25 seconds (maximum not more than 30 seconds) and the portion of the specimen outside the clamp shall not be completely burned in the test. 08-12-0236A Materials which compl with the above requirements and do not drip any flaming particles or droplets during the burning test will classify as "self-extinguishing, Class X." Materials which comply with the above requirements, but drip flaming particles or droplets which burn only briefly during the test will classify as "self-extinguishing Class II." Class SE-0 is given to materials wherein the duration of flaming or glowing combustion averages less than 5 seconds under the conditions above.

Flammability of Plastics Using the Oxygen Index Method ASTM Test D-2863 is used With the General Electric Flammability Index Tester Model Α-Ί990-Α. A sample bar 0.32 x 1.27 x 12.7 cm is molded and placed in the above tester. The tester is attached to an oxygen tank and a nitrogen tank. By means of control valves, an atmosphere a can be created inside the tester containing any desired ratio of nitrogen to oxygen. The lower the oxygen concentration which will support combustion, the higher the degree of flammability of the test specimen. It is generally considered that the oxygen content should be at least 20% for combustion support in order for a material to be considered sufficiently flame resistant. Of course, the higher the value, the better. A propane torch flame is applied to one end of the test specimen in the tester. If the specimen burns for at least three minutes, the concentration of oxygen is reduced. By a system of trial and error with several specimens the limiting oxygen concentration is determined where burning not be supported at an oxygen concentration 1% lower. This limiting concentration is then reported as the Limiting Oxygen Index (LOI).

Weight Average Particle Size Test The weight average particle size is determined by dispersing the polyblend In dimethylformamide using 2 grams of polyblend in 98 grams of solvent. The dispersion is then diluted 3 to 1 with methyl-ethyl-ketone and analyzed according to the published procedure of Groves, M.J., Kaye, B.H., Scarlett, B., "Size Analysis of Subsieve Powders Using A Centrifugal Photosedimentometer ," British Chemical Engineering, Vol. 9:7H2-7 (196M). A Model 3000 Particle Size Analyzer available from Martin Sweets Company, 3131 West Market Street, Louisville, Kentucky was used.

Impact Strength Test ASTM Test D-256 - Method A commonly known as the Izod Test. Impact values are a measure of toughness and high values are needed for engineering applications preferably greater than 8.2 Kg cm/cm notch.

Heat Distortion Temperature Under Load ASTM Test D-618 was used with a load of I8.56 Kg/cm2.

Test values here should remain high so that the polyblend is functional at high temperatures in engineering applications, e.g. automotive and appliances.

Graft Level Test Weigh out 1 gram of grafted resin and disperse in 20 ml of a solvent of 50/50 dimethylformamide/methyl ethyl ketone.

The matrix polymer will dissolve. Centrifuge and decant Sample Preparation The plastic to be tested Is usually In comminuted form. A portion of the plastic particles are compression molded at 166 - 182°C. at 506 Kg/cm2 to form a sheet about 0.32 cm thick. Sample bars are then cut from the molded sheet having dimensions of 0.32 x 1.27 x 15.2 cm.

Embodiments Samples of polyblend polymers are prepared using un-grafted and grafted chloroprene rubber to demonstrate the properties of the two types and their ability to provide self-extinguishing properties and impact strength to the sytrene family of polymers. Other pertinent physical properties are measured such as the heat distortion under load and gloss .

EXAMPLE 1 CONTROL A typical polyblend of styrene-acrylonitrile copolymer (SAN) containing about 25% AN and a grafted polybutadiene rubber grafted with a 75/25 S/AN ratio of monomer is used. The polyblend containing about 23% rubber and about 77% SAN by weight, is available from the Monsanto Company of St. Louis Missouri under the trademark Lustran R) ABS 710. The impact strength is 27.25 Kg cm/cm notch at 23°C; the percentage of oxygen that just supports combustion is 18% (LOI) and will not pass the UL 9^ test. Those skilled in the art would recognize that this polyblend has a desirably high impact strength but that it is too low in flame retardancy for such uses. The grafted rubber then has the necessary compati - - * EXAMPLE 2 CONTROL A polyblend with SAN copolymer sold by the Monsanto (R) Company of St. Louis, Missouri, under trademark Lustranv ' SAN 21 is prepared using 65 parts SAN polymer, 30 parts of a commercially available solid, soluble non-crosslinked chloroprene rubber and 5 parts of Sb20g. The polyblend is colloided on a Boiling roll mill using 9.1 Kg/cm2 steam pressure to reach a melt temperature of 204 - 232°C, for 5 minutes after which the polyblend is stripped from the mill, cooled and comminuted. Test samples were prepared. The UL 91* test gives values of SE-0 showing the polyblend is self-extinguishing. The impact strength test gives an Izod of less than.2.73 Kg cm/cm notch demonstrating that chloroprene rubber that is both a non-crosslinked and ungrafted rubber lacks the necessary interfaclal compatibility with the rigid phase SAN copolymer to produce a tough polyblend.

EXAMPLE 3 CONTROL A polyblend is prepared by first blending an emulsion of a SAN copolymer with an emulsion of a crosslinked commercially available chloroprene rubber and coagulating with aluminum sulfate to form a crumb having 0% rubber and 60% SAN. The emulsion SAN copolymer is prepared using the following formulation based on parts per 100 parts of total monomers : - 18 - Styrene Acrylonitrile Water Potassium Persulfate Terpinoline Rubber Reserve Soap (Commercially available sodium salt of oleic, stearic and palmitic acids) (Commercially available 0.005 sodium salt of a formaldehyde napthalene sulfonate. ) The monomers are dispersed in water containing the soap and Darvan and polymerized at 95°C under reflux for 3 hours and ^5 minutes in the presence of the potassium persulfate and catalyst and the terpinoline modifier under agitation. The emulsion contains 46.3* of SAN polymer in the emulsion.

The average particle size of the rubber particles in the chloroprene rubber latex and the polyblend is observed to be about 0.12 microns (weight average based on centrifugal photo sedimentation method.) The crumb is mechanically blended with a SAN copolymer Lustran^ SAN 21 sold by Monsanto Company of St. Louis, Missouri, and tested as in Example 2 with the blend having 10 parts chloroprene rubber, 65 parts SAN polymer and 5 parts Sb20g. The Izod test values are 8.2 Kg cm/cm notch. The UL-94 test have SE-0 values. The percentage of oxygen to support combustion is 25.1% (LOI) and the heat distortion under load at I8.6 Kg/cm2 is 91°C It is evident that the polyblend is self-extinguishingj has flame retardancyj has a high heat distortion temperature and has a higher degree of toughness because the rubber is crosslinked. The emulsion blending does provide a better polyblend than that of Example 2 having an impact strength of 8.2 Kg cm/cm notch, versus 2.73 Kg cm/cm notch for a blend of chloroprene rubber and copolymer wherein the rubber is not crosslinked.

EXAMPLE H The grafted chloroprene rubber interpolymer concentrate is prepared by the following procedure : A reaction mixture of by parts: Chloroprene Rubber 100 (50% solids) Styrene Monomer 28 Acrylonitrile Monomer 12 Emulsifying Agent 1 (Sodium salt of an alkyl diphenyl oxide sulfonate) Potassium persulfate initiator 1 Terpinoline Modifier 0.5 Water 260 The chloroprene latex, water, Dowfax and terpinoline are added to a stirred reactor and brought to 85°C The monomers and initiator are added to the reaction over a period of 2 hours with a final finishing period of 1-1/2 hours to give a latex having a solids level of 35% . The average particle size of the rubber particles in the latex is observed to be about 0.12 microns (weight average based on centrifugal photo sedimentation method.) A grafted chloro-prene rubber is formed along with SAN copolymer giving an - - interpolymer concentrate of the present invention. The inter-polymer concentrate comprises about 71.5% by weight chloroprene rubber, 10.3% by weight of SAN copolymer as graft copolymer on the rubber and 18.2% SAN copolymer as free copolymer.

The chloroprene rubber has 14.4% by weight of grafted SAN copolymer considering. the ratio of the weight of graft copolymer to the weight of rubber as 10.3 '71.5 or 14.4% by weight based on chloroprene rubber. The resulting latex is further blended with the SAN latex of Example 3 and coagulated using aluminum sulfate to recover the solid polyblend. Analysis of the polyblend shows the blend to be 30% polychloroprene having 14.4 weight percent of SAN grafted based on rubber; 65% SAN polymer including the grafted SAN. The blend is further melt colloided on a mill as in Example 2 with 5% Sb 0 and the comminuted polyblend tested. The Izod impact strength is 23.98 Kg cm/cm notch; the heat distortion temperature under load is 88°c.; the UL-94 test values are SE-0 and the percentage oxygen to support combustion is 25.6% (LOI). It is evident that the grafted chloroprene interpolymer concentrate provides the polyblend with high impact strength or toughness; self-extinguishing properties and high flame retardancy without sacrificing the heat distortion temperature for functional engineering uses.

EXAMPLE 5 Example 4 is repeated running to a total lower conversion of 75% wherein the SAN graft level on the chloroprene rubber of the literpolymer concentrate is 11.4% by weight based on 65% SAN polymer and 5% S 203 as in Example The admixture is melt colloided as in Example 2 and the comminuted polyblend tested. The Izod impact strength is 12.5 Kg cm/cm notch , showing a lower level of toughness when the graft level is lower and provides lower interaction with the rigid SAN phase but higher than the ungrafted chloroprene rubbers of Examples 1 and 2. The test gives values of SE-0 showing the polyblend to be highly self-extinguishing. The percentage oxygen to support combustion is 25.3% (LOI) showing high flame retardancy and the heat distortion temperature under load is 92°C, showing the polyblend is self-extinguishing and tough without sacrificing the heat distortion temperature for functional engineering uses.

EXAMPLE 6 A higher grafted chloroprene is prepared by using the following formulation based on parts per 100 parts of total monomers : Styrene 70 Acrylonltrile 30 Chloroprene Rubber 100 ( 50 Solids) Terpinoline 1 Commercially available sodium salt of a formaldehyde napthalene sulfonate 1 Potassium Persulfate 1 Rubber Reserve Soap 1 Water 270 - 22 - The sodium salt of a formaldehyde napthalene sulfonate is added to the water and chloroprene rubber latex then dispersed followed by the monomers and the catalyst. The monomers and catalyst are added at 25 parts per hour on 70/30 ratio basis with proportionate amounts of catalyst over a 4 hour period. The Rubber Reserve Soap is added after one half of the monomers have been added. The polymerization is carried out at 85°C, under agitation to give a latex with about 35% final solids. A grafted chloroprene rubber is formed along with SAN copolymer giving an interpolymer concentrate of the present invention. The interpolymer concentrate solids of the latex analyzes as 50% by weight chloroprene rubber, 2 % by weight of SAN copolymer as graft copolymer and 26% by weight of SAN as free copolymer based on the total weight of the interpolymer concentrate. The chloroprene rubber has B% grafted SAN copolymer based on the weight of the rubber. The resulting latex is further blended with the SAN latex of Example 3 and coagulated using aluminum sulfate to recover the solid polyblend. The average particle size of the rubber particles in the polyblend are observed to be about 0 .12 microns (weight average). The SAN graft on the chloroprene rubber is *l8 .0i by weight based on rubber.

The final polyblend admixture contains 30% chloroprene, 65% SAN polymer and 5% Sb20g as in Example 4 . The admixture is melt colloided as in Example 2 and the comminuted polyblend tested. The Izod impact is Ί. 36 Kg cm/cm notch, showing low impact values and toughness; the UL-91* test shows values of SE-0 as self-extinguishing; and the heat distortion under - - V EXAMPLES 7, 8. ? and 10 Latex blends of lower graft and higher graft poly-chloroprene rubber are made using the grafted rubber inter-polymer concentrates of Examples M and 6 as low and high respectively to give blends that have 30% chloroprene rubber by weight. These interpolymer concentrate blends are in turn polyblended with SAN latex as in Example 3. The final admixtures were polyblended to have the following compositions as tabulated below along with the physical tests of each composition. The Peak Hunter Gloss values are determined by measuring the gloss of a molded sample on a Hunter Laboratory Model D-36 Glassmeter supplied by Hunter Associates of Mc Lean, Virginia.

EXAMPLES 7 8 £ 10 Low Graft Rubber 30 15 9 0 High Graft Rubber 0 21 30 SAN polymer 65 65 65 Antimony Oxide 5 5 5 5 Izod Impact Strength (Kg cm/cm notch) 24.0 16.9 1H.7 HDTUL (Kg/cm2) (°C) 88 83 83 80 UL-91* SE-0 SE-0 SE-0 SE-0 Peak Hunter Gloss 0 4 23 64 It is evident from the test values that low graft chloroprene rubber interpolymer concentrates can upgrade the high graft chloroprene rubber interpolymer concentrates to a high level of toughness bringing them from about 4.

- - V generally accepted for Impact polyblends. It is also evident that the gloss level for the high graft rubber types is higher than for the low graft rubbers.

EXAMPLES 11 - 15 Rubber Particle Size Parameters The chloroprene latex (50* solids) is observed to have an average rubber particle size of about 0.12 microns (weight average). The latex is partially agglomerated to give larger particles for testing as in Examples 4 - 10.

Agglomeration is carried out according to the following procedures using: Chloroprene Rubber Latex 100 pts. (25% solids) Emulsifying Agent .0 5 pts.

Acetic Anhydride 6 pts.

Water 300 pts.

Dissolve 6 parts of the acetic anhydride in 60 ml of water and add to the rubber latex containing the emulsifying agent. Stir for 30 seconds after addition and let stand 30 minutes. Add 2 pts. of emulsifying agent to the emulsion to stabilize the emulsion. The average particle size of the rubber particle is observed to be about 0.50 microns (weight average). The particle size of the agglomerated rubber can be varied using modifications of the above procedure. The acetic anhydride undergoes hydrolysis and reacts with the rubber emulsifying agents to render the emulsion less stable causing agglomeration of the rubber particles. Hence, larger particles can be obtained by - - increasing the amounts of acid anhydride used consistent with keeping the emulsion stable for subsequent handling, blending and grafting reactions. The chloroprene rubber latex has a sodium rosin soap as an emulslfler which is protonlzed by the anhydride to allow agglomeration. The emulsifying agent is then added in larger amounts to stabilize the larger particles giving a stable emulsion. Agglomerated particles as large as 1.5 microns are readily obtained using the above procedures.

The above emulsion is then grafted according to the procedure of Example 6 using varying amounts of terplnollne and catalyst to vary the conversion and percent graft. The grafted rubber lnterpolymer concentrate latex is then processed into a polyblend with SAN polymer latex as in Example 6. Examples 11 - 15 are detailed as follows: EXAMPLES 12 Catalyst 1.0 1.0 1.5 1.0 1.0 Terplnollne (parts) 1.0 0.5 0.0 0.0 0.5 Graft level (wgt. *) 2.5 8.9 15.0 21.9 27.3 % Conversion 61» 77 85 99 82.0 Wgt. % rubber 30 30 30 30 30 Wgt. % SAN 65 65 65 65 65 Wgt. % Sb203 5 5 5 5 5 Izod impact (Kg cm/cm notch) 12.5 12.5 12.5 15.8 8.2 Hunter Gloss 23 m 49 50 — HDTUL °C 84 82 85 85 81 w The data show that the percent graft of the interpoly-mer concentrate can be varied from about 2.5 to about 30% with an average chloroprene rubber particle size of about 0.5 microns (wgt. average) before impact strength begins to drop with the gloss improving as the weight % graft increases . It is also evident that these low graft rubbers having an average particle size of about 0.50 microns have reasonably high gloss compared to low graft chloroprene rubbers of Examples 4-5, having an average rubber particle size of about 0.12 microns. This would indicate that the smaller rubber particle size rubbers provide much greater surface area for grafting, hence, are- effectively less grafted and can agglomerate to give larger particles to improve impact strength but then lower gloss. Regardless of the theory, the percent graft of the interpolymer concentrate should be adjusted relative to particle size to provide both good impact strength and gloss within the parameters shown.

In addition, it is observed that the heat distortion is high and polyblends have excellent self-extinguishing properties.

EXAMPLES 16 - 17 Examples 7 - 10 are repeated using a blend of high graft rubber interpolymer concentrate of Example 6 having an average rubber particle size of about 0.12 microns and a graft level of 48.0 weight percent and the low graft rubber interpolymer concentrate of Example 13 having an average rubber particle size of about 0.5 microns and a graft level of about 15.0 weight percent. The test results are: 08-12-0236A Example Example 16 17 Wgt . % Low Graft Rubber 3 6 Wgt. % High Oraft Rubber 27 2 Wgt. % SAN Polymer 65 65 Wgt. ί Sb 0 5 5 Izod Impact Strength 11· 13.1 (Kg cm/cm2) Hunter Gloss M5 60 HDTUL (°C) 80 81 UL-91* SE-0 SE-0 The test data show high Impact polyblends can be produced using 10 to 20Ϊ by weight of low graft chloro-prene rubber having a particle size In the range of about 0.50 microns with 8035 to 90J? of a high graft chloroprene rubber having rubber particles In the range of about 0.12 microns Also, the gloss of such blends has high values along with other good heat distortion temperatures and excellent self-extinguishing properties.

EXAMPLE 18 Part A Fourteen parts of a soluble butadiene rubber are dissolved in 26.0 parts of acrylonitrile and 60.0 parts styrene. There are added thereto 0.07 part of a mixture of terbutyl peracetate 0.05 part di-tert-butyl peroxide and stabilizers. The mixture is heated to 100° centigrade with stirring. Terpinolene is added as a chain transfer agent over a period of approximately five hours in an amount of about 0.1 part per hour for approximately five hours, at - - At 30.0 percent conversion of the monomers, the partially polymerized syrup is dispersed in 120.0 parts water to which is added 2.0 parts styrene and, as a suspending agent, 0.3 part of an interpolymer of 95.5 mol percent of acrylic acid and 4.5 mol percent of 2-ethylhexylacrylate which has a specific viscosity of about 4.0 as determined in a 1.0 percent solution in water at 25° centigrade. The resulting suspension is stirred and heated to polymerize the remaining monomer, cooled, centrifuged, washed and dried to recover the grafted rubber interpolymer concentrate in the form of small spherical beads. The ratio of superstrate to substrate is about 0.9 to 1.0:1.0, and the particle size of the grafted rubber is about 0.9 micron. The interpolymer concentrate analyzes as 1 rubber by weight, 1H by weight of grafted SAN copolymer and 72% SAN by weight.

Part B Seventy grams of beads from Part A are milled and melt colloided as in Example 2 with the 930 grams of the final polyblend admixture of Example 6. The final polyblend now contains about 1% of polybutadiene rubber. The milled polyblend is comminuted and tested.

Part C Using the above procedure 210 grams of Part A were colloided with 790 grams of the final polyblend of Example 6. The final polyblend now contains about 3* nolybutadlene rubber. The milled Dolvblend is eommimitert es ed. The test data on the two polyblends B and C are shown below.

- - Polyblend UL-94 Impact HDTUL Qloss Test Test Test °C Test Part B SE-0 13,6 Kg cm/cm 86 70 notch Part C SE-0 38.2 Kg cm/cm 81 50 notch The soluble rubbers used in Example 18 are commercially available diene rubbers such as high-cis polybutadlene rubbers having a cis-isomer content of about 30% to 98* and having a second order transition temperature, Tg, of from about -50°C. to -105°C. as determined by ASTM Test D-716-52T. Other soluble diene rubbers include copolymers of conjugated 1,3 butadiene with up to equal amounts by weight of one or more copolymerlzable monoethylenlcally unsaturated monomers such as monovinylidene aromatic monomers, e.g. styrene, and monoethylenlcally unsaturated nitriles, e.g. acrylo-nitrile. The preferred diene copolymer rubbers are those having a second order transition temperature, Tg, range of from about -20°C. to -70°C.

The polychloroprene rubbers contained in an emulsion and used in tixe preparing the concentrates of the present invention are readily available in the form of latices.

These latices have a rubber solids content of about 3**·5Ϊ to 6θί, a pH of about 9 to 13» latex specific gravity of about 1.10 to 1.15, rubber specific gravity of 1.23 to 1.42, latex viscosity of 16 to 400 cps. (Brookfield viscosity) and the latices are stabilized by anionic or cationic emulsifiers. The rubbers contained in the latices are crosslinked and are a medium to high gel types, are 08-12-0236A (MS-2-1/2 min 100°C.) The rubber particle size distribution of such latices can be varied so as to give the selected weight average particle aize range desired and disclosed in this invention.

EXAMPLES 19 - 23 Polyblend Proportions Tested The grafted chloroprene latex of Example 6 having about 355? solids was coagulated with aluminum sulfate and the solid recovered as a crumb interpolymer concentrate and dried. The solids analyze ^% grafted rubber and 26% SAN copolymer as the rigid phase. The rubber crumb interpolymer concentrate is 50% chloroprene rubber and has ^8% by weight of grafted SAN contributing 2 % SAN copolymer to the crumb. The rubber has a1 particle size of 0.12 microns.

The grafted rubber latex' of Example 13 having a rubber particle size of 0.5 microns is coagulated with aluminum sulfate, recovered as a crumb interpolymer concentrate and dried. The solids analyze 50% by weight rubber, having a graft level of 15% SAN contributing 7.5% by weight of SAN to the crumb along with ^2.5% SAN copolymer as the rigid phase.

The SAN latex of Example 3 is coagulated with aluminum sulfate and the solids recovered as a free flowing SAN powdered polymer. The grafted crumb interpolymer concentrate of Examples 6 and 13 and the SAN polymer of Example 3 are dry blended with SbgO^ to form admixtures and melt blended at 2l8°C. to a uniform polyblend. The polyblends are molded into specimens and tested for self-extinguishing properties and impact strength. The proportions of the above described 08-12-0236A EXAMPLES Proportions by Weight % 11 20 21 22 23 Admixture Ex. 6 Concentrate 2*1.0 32.0 36.8 64.0 64.0 Ex. 6 Rubber 12.0 16.0 18.4 32.0 32.0 Ex. 6 Graft SAN 5.8 7.7 6.8 15.4 15.4 Ex. 6 SAN 6.2 8.3 11.6 16.6 16.6 Ex. 13 Concentrate 6.0 8.0 9.2 16.0 16.0 Ex. 13 Rubber 3.0 4.0 4.6 8.0 8.0 Ex. 13 Graft SAN 0.5 0.6 0.7 1.2 1.2 Ex. 13 SAN 2.5 3.4 3.9 6.8 6.8 Ex. 3 SAN 55.0 51.0 44.0 16.0 19.0 Total Rubber 15.0 20.0 23.0 40.0 40.0 Total SAN 70.0 71.0 67.0 56.0 59.0 Sb2 °3 15.0 9.0 10.0 4.0 1.0 UL 94 Test SE-01 SE-01 SE-02 SE-0 SE-o3 Izod 5.45 8.2 9.8 17.4 19.6 (1) UL 94 with 0.32 cm thick test specimen. (2) UL 9 with 0.18 cm thick specimen. ( 3 ) UL 94 with 0.64 cm thick specimen.

It is evident from the test data above and from the examples previously described that the grafted chloroprene rubber interpolymer concentrate when polyblended provides good impact over the range of 15 to 40$ by weight and pro

Claims (23)

08-12-0236A WHAT IS CLAIMED IS:

1. A fire retardant thermoplaetlc interpolymer concentrate characterized by: (A) from 1% to &2% by weight of a polymer of at least one monovlnylldene aromatic hydrocarbon monomer and an ethylenically unsaturated nitrile monomer wherein said ethylenically unsaturated nitrile monomer moiety constitutes from 0Ϊ to 90% by weight of the said polymer, and (B) from 18% to 99% by weight of a grafted chloro- prene rubber copolymer said rubber grafted with: (1) at least one monovlnylldene aromatic hydrocarbon monomer, and (2) an ethylenically unsaturated nitrile monomer wherein said ethylenically unsaturated nitrile monomer moiety constitutes from 0% to 90Ϊ by weight of the total monomers grafted, wherein a chloroprene rubber moiety is present in from 15% to 75% by weight of the interpolymer concentrate with polymer (A) and copolymer (B) obtained as said interpolymer concentrate by the polymerization of at least one of said monomers In the presence of said chloroprene rubber.

2. An Interpolymer concentrate of Claim 1 characterized hydrocarbon wherein said monovlnylldene aromatic/monomer is selected from the group consisting of styrene, aralkylstyrenes, alphalkylstyrenes, alphahalostyrenes, arhalostyrenes and m 08-12-0236A

3. The interpolymer concentrate of Claim 1 characterized wherein at least one of the monovlnylldene aromatic hydrocarbon monomers is styrene.

4. . The interpolymer concentrate of Claim 1 characterized hydrocarbon , wherein at least one of the monovlnylldene aromatic/ monomers is alphamethylstyrene.

5. The interpolymer concentrate of Claim 1 characterized hydrocarbon wherein at least one of the monovlnylldene aromatic /monomers is monochlorostyrene .

6., The interpolymer concentrate of Claim 1 characterized hydrocarbon wherein at least one of the monovlnylldene aromatic /monomers is monobromostyrene.

7. The interpolymer concentrate of Claim 1 characterized wherein said ethylenlcally unsaturated nitrile is selected from the group consisting of acrylonltrlle, methacrylonitrile, ethacrylonitrile and mixtures of the same.

8. The interpolymer concentrate of Claim 1 characterized wherein said ethylenlcally unsaturated nitrile is acrylonltrlle.

9. The interpolymer concentrate of Claim 1 characterized wherein the ethylenlcally unsaturated nitrile is methacrylonitriie.

10. An interpolymer concentrate of Claim 1 characterized wherein said grafted chloroprene rubber is present in from about 18.0% to 99% by weight of the interpolymer concentrate providing from 1555 to 75% by weight of chloroprene rubber in the interpolymer concentrate.

11. An interpolymer concentrate of Claim 1 characterized wherein a first grafted chloroprene rubber having an average 08-12-0236A average, from O.^O to 1.5 microns said first grafted rubber being present from 50.0 to 97.0 percent of the total weight of the first and second grafted rubbers; said first grafted rubber being grafted from about 10 to 100? by weight with said monomers and said second grafted rubber being grafted from about 5 to h0% by weight with said monomers.

12. An interpoly er concentrate of Claim 1 characterized wherein a grafted chloroprene rubber having a weight average rubber particle size from 0. to 1.0 microns, being grafted with from about 10¾ to 1001 by weight of said monomers based on the weight of the chloroprene rubber.

13. An interpolymer concentrate of Claim 1 characterized wherein said grafted chloroprene rubber is crosslinked and has a ooney viscosity of about at least 200 (MS-2-1/2 min. 100°C).

14. I1*. An interpolymer concentrate of Claim 1 characterized wherein said grafted chloroprene rubber has a rubber moiety comprising chloroprene copolymerlzed with at least one monomer copolymerizable with said chloroprene.

15. An interpolymer concentrate of Claim l1* characterized wherein said grafted chloroprene rubber has a rubber moiety comprising chloroprene copolymerlzed with at least one monomer selected from the group consisting of styrene, acrylonitrile, methacrylonitrile, butadiene or isoprene and mixtures thereof.

16. An interpolymer concentrate of Claim 15 characterized wherein said monomer is styrene.

17. An interpolymer concentrate of Claim 1 characterized 08-12-0236A methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate or mixtures thereof,

18. An lnterpolymer concentrate of Claim 1 characterized wherein about 10-30$ by weight of the chloroprene rubber moiety is replaced with a diene rubber of polybutadlene, butadiene-styrene , butadiene-acrylonitrile, butadiene-methacrylonitrile or butadiene-styrene-acrylonitrile or mixtures thereof; said diene rubber being grafted with: hydrocarbon (1) at least one monovinylidene aromatic/ monomer and, (2) an ethylenically unsaturated nitrile monomer wherein said ethylenically unsaturated nitrile monomer moiety constitutes from 0 to about 90$ by weight of the total monomers grafted wherein said grafted diene rubber having a weight average rubber particle size of from 0.7 to 1.5 microns is grafted with from 50%" to 1 0$ by weight of said monomer and wherein said grafted chloroprene rubber has a weight average rubber particle size of from .05 to 0.20 microns being grafted from about 10 to 100$ by weight with said monomers .

19. An lnterpolymer concentrate of Claim 18 charac- hydrocarbon terized wherein said monovinylidene aromatic/monomer is styrene.

20. An lnterpolymer concentrate of Claim 18 characterized wherein said ethylenically unsaturated nitrile monomer is acrylonitrile.

21. An lnterpolymer concentrate of Claim 18 characterized wherein said polybutadlene rubber has a cls isomer content of 08-12-0236A 30% to 98* and a Tg range of from -50°C. to -105°C, said butadiene copolymer rubbers having a Tg range of from -20°C. to -70°C.

22. . An Interpolymer concentrate of Claim 18 characterized wherein said Interpolymer concentrate having interpoly-merlzed a monomer of acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate , ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate or mixtures thereof.

23. . A fire retardant thermoplastic Interpolymer concentrate characterized by: (A) from 1% to 82% by weight of a polymer of at hydrocarbon least one monovlnylldene aromatic/ monomer and an ethylenically unsaturated nitrile monomer wherein said ethylenically unsaturated nitrile monomer moiety constitutes from 0% to 90% by weight of the said polymer blended with (B) from 18$ to 99% by weight of a grafted chloro- prene rubber copolymer said rubber grafted with: ( 1 ) at least one monovlnylldene aromatic hydrocarbon monomer, and ( 2 ) an ethylenically unsaturated nitrile monomer wherein said ethylenically un- saturated nitrile monomer moiety constitutes from 0% to 90% by weight of the total monomers grafted and said grafted chloroprene rubber comprises a first grafted chloroprene rubber wherein the avera e raft rubber article size 1 1 based on weight average, is from 0.01 to 0.35 miorons, a second graft chloroprene rubber wherein the average rubber particle size, based on weight average, is from 0.^0 to 1.50 microns, said first grafted rubber is grafted from about 10 to 100* with said monomers, being present in from 50.0 to 97.0 percent of the total weight of the first and second grafted rubbers, said second grafted rubber is grafted from 5 to k0% with said monomers; said grafted rubbers providing 15% to 75% by weight of chloroprene rubber in the interpolymer concentrate; said grafted chloroprene rubber being crosslinked having a ooney viscosity of at least 200 (MS-2-1/2 min., 100°C), wherein polymer (A) and copolymer (B) obtained as interpolymer concentrate by the polymerization of at least one of said monomers in the presence of said chloroprene rubber. 2*1. An interpolymer concentrate of Claim 23 characterized wherein polymer (A) is SAN and (B) is grafted with styrene and acrylonitrile . P. O. B ox 331 16 , T e l - A v i v Atto rney s f o r Applicant