HIGH IMPACT POLYSTYRENE CONTAINING LOW MOLECULAR WEIGHT BROMINATED POLYSTYRENE

Abstract: Effective amounts of low molecular weight brominated polystyrenes unexpectedly provide good property retention and yet achieve desired flame retardance, for example, UL-94 VO in high impact polystyrene. In contrast, high molecular weight brominated styrene polymers (degree of polymerization equals 2,000) do not provide good property retention such as impact strength and toughness in high impact polystyrene. The degree of polymerization of the brominated polystyrenes of the present invention is generally from about 3 to about 20 and can have a considerable variation in the amount of halogenation. The high impact polystyrenes blended with the low molecular weight brominated polystyrenes are readily processed by conventional equipment.

Description: HIGH IMPACT POLYSTYRENE CONTAINING LOW MOLECULAR WEIGHT BROMINATED POLYSTYRENE FIELD OF THE INVENTION The present invention relates to the use of l molecular weight brominated polystyrenes in high impa polystyrene, whereby good retention of physical prope ties including impact strength is obtained whi achieving excellent flame retardancy. BACKGROUND A brominated polystyrene having a degree polymerization of approximately 2,000 when used in hi impact polystyrene provides excellent flame retardan and stability but has a very negative effect on k physical properties such as impact strength. This effe is generally unacceptable. U.S. Patent No. 3,075,944 relates to fla retardant compositions containing polyolefins which c be made by substituting a diaro atic or an aromati aliphatic ether containing at least three bromine atoms U.S. Patent No. 3,830,766 relates to flam proofing acrylonitrile-butadiene-styrene (ABS)polymers incorporating therein an aromatic bromine compoun antimony trioxide or antimony oxychloride and optional an organo chlorine compound. U.S. Patent No. 3,897,373 relates thermoplastic molding compositions based on styr polymers and flameproofed with an organic bromine c pound. They contain a synergistic azo compound and be converted to self-extinguishing shaped articles profiles. U.S. Patent No. 3,943,195 relates to a thermo plastic molding material based on styrene polymers an olefin polymers which have been flameproofed with a organic bromine compound. Brominated oligomers or poly mers of dialkylbenzenes, trialkylbenzenes or tetraalkyl benzenes serve as flameproofing agents. The moldi material may be processed into self-extinguishing mol ings. U.S. Patent No. 3,962,164 relates to flam proofing acrylonitrile-butadiene-styrene (ABS) polymer incorporating therein certain mono- and diphenyl aromat bromine compounds such as octabromodiphenyl, antimo trioxide, or antimony oxychloride and optionally organo chlorine compound. U.S. Patent No. 4,049,622 relates to therm plastic molding compositions based on styrene polymer preferably formed styrene polymers, which have be flameproofed with an organic bromine compound. U.S. Patent No. 4,074,032 relates to a proce for the manufacture of heat-stable, brominated olig styrenes by brominating selectively hydrogenated olig styrenes in halogenated solvents in the presence of Lew acids at from about minus 25°C to 20°C. The brominat oligomers are highly heat-stable and can be processed, themselves or as components of mixtures with oth thermoplastics, to give various shaped articles. U.S. Patent No. 4,107,231 relates to flam proofed linear polyesters containing, as flameproofi agents, halogenated oligomeric styrenes and εynergist compounds. U.S. Patent No. 4,137,212 relates to a flam proofed nylon molding composition which can be process by thermoplastic methods and which contains, as t flameproofing agent, from 5 to 30 percent by weight brominated styrene oligomers and a synergistic met oxide. The composition may be used for the manufactu of injection moldings for the electrical industry. U.S. Patent No. 4,143,221 relates to styre polymers or copolymers containing bromine which a manufactured by cationic polymerization of the monome or of the monomer plus a copolymerizable monomer of t isobutylene or nuclear-alkylated styrene type, in organic solvent in the presence of a Lewis acid catalys Bromine is then added to the solution without fir working up the latter. The catalyst used for the bro nation is the same as that used for the polymerizatio If necessary, fresh catalyst may be added before t bro ination. After completion of the bromination, reaction solution is extracted with water until it bromide-free, and the solvent, generally a halohyd carbon, is then stripped off. Products containing up about 80 percent by weight of bromine may be obtain They have a pale yellowish color and exhibit no signi cant decomposition up to 340°C. They may be used flameproofing agents for thermoplastics. U.S. Patent No. 4,151,223 relates to fibers filaments of linear thermoplastic polyesters, contain halogen-containing flameproofing agents and synergis agents therefor, in which the flameproofing agents chlorinated and/or brominated oligomeric styrenes. fibers and filaments of the invention are used for manufacture of textiles of low flammability. U.S. Patent No. 4,200,702 relates to ther plastic molding compositions based on rubber-modif styrene-acrylonitrile copolymers containing a halogena styrene oligomer as the effective flameproofing ag which is sufficiently heat-stable, does not interf with processing on conventional machinery, does corrode or cause coatings on such machinery, and virtually no adverse effect on the impact strength of t polymers. The flameproofing agent as a rule has a degr of polymerization of from 3 to 200 and can be incorp rated into the polymer by conventional methods; t polymer may or may not contain additional synergist agents and processing auxiliaries, which are incorporat in the conventional manner and in the convention amounts. U.S. Patent No. 4,360,455 relates to a mixtu of brominated oligomeric polystyrenes having a degree polymerization of from 3 to 400, and low molecular weig brominated aromatic compounds of the diphenyl ether ty which are obtained by polymerizing the non-brominat starting materials, in a halohydrocarbon solvent, using Lewis acid catalyst. The reaction mixture is then brom nated and extracted with water to remove hydrogen bromi and catalyst, and the solvent and volatile constituen are separated from the product. The bromination carried out at from minus 30°C to 130°C. The fin mixtures have a low melt viscosity and are therefo particularly suitable for incorporation, as a flam proofing agent, into thermoplastics. U.S. Patent No. 4,352,909, to Barda et relates to a process for producing a trihalogenat polystyrene flame retardant for synthetic resins, where high molecular weight polystyrene is reacted with bromi chloride in a chlorinated hydrocarbon solvent, und substantially anhydrous conditions, in the presence of catalytic amount of a Lewis acid. German Patentschrift 151,075 relates to sel extinguishing polystyrene compositions containing bro nated oligomers of alpha methyl-styrene as flame ret dants with minimum loss of mechanical properties. oligomer contains from 40 to 70 weight percent ring-bo bromine and has a molecular weight of from about 1,000 about 5 , 000. SUMMARY OF THE INVENTION It has been ound that the molecular weight a brominated low molecular weight polystyrene is important factor in property retention in that une pectedly good property retention has been obtained wh said polystyrenes are blended with high impact pol styrene (HIPS) and that good or excellent flame retar ancy, for example UL-94 VO at 1/8 inch thickness is al achieved. The low molecular weight brominated pol styrene of the present invention generally have a degr of polymerization of from about 3 to about 20 and halogenated content, e.g., bromine, of from about percent to about 76 percent by weight. DETAILED DESCRIPTION OF THE INVENTION High impact polystyrene is commercially ava able and is well known to the literature as well as the art. High impact polystyrene (HIPS) is produced f styrene monomers along with elastomers and is genera available in various impact-strength grades. HIPS generally produced by introducing elastomers such polybutadiene into the polystyrene matrix for imp modification and is generally produced by either a s pension process or more preferably by a mass continu polymerization process. The low molecular weight brominated polys renes of the present invention are oligomers and gen ally have a degree of polymerization, i.e., number repeating units, of from about 3 to about 20, genera from about 5 to about 15, desirably from about 6 to ab 12, and preferably from about 7 to about 9. The repe ing units generally have the formula —CH—CH 2 — from about 1.5 to about 4.0 molecules per repeating uni The amount of the bromine is generally from about percent to about 76 percent, desirably from about percent to about 71 percent, and preferably from about percent to about 70 percent by weight with regard to t total weight of each repeating unit. The molecul weight distribution of the oligomers is generally narr such as at 4.0 or less, and preferably 2.5 or les Retention of impact properties when using l molecular weight brominated polystyrenes as flame reta dants is a function of molecular weight and the degree bromination. As the molecular weight increases, impa retention will decline at a constant bromine leve Conversely, as the bromine content incorporated with t polystyrene increases, impact retention will decline at given or constant molecular weight. Therefore, optimiz tion of property retention is generally a balancing such factors. The amount of the low molecular weight bro i ated polystyrene oligomer utilized is generally an effe tive amount to achieve good flame retardancy. In oth words, effective amounts of the low molecular weig brominated polymers are utilized to produce good fla retardancy but as an unexpected result, effective superior impact retention is obtained, especially comparison with high molecular weight brominated pol styrene having a degree of polymerization of approx mately 2,000. An effective level of flame retardan would be, for example, VO at 1/8 inch thickness UL-9 Physical properties which are notably retained inclu impact strength such as measured by notched Izod, rever Izod, Gardner impact, elongation, and the like. Effective amounts of the brominated polystyre oligomer of the present invention are generally f about 3 percent to about 20 percent by weight, desira from about 10 percent to about 18 percent by weight, preferably from about 14 to about 16 percent by weight the oligomer based upon the total weight of the oligo and the high impact resistant polystyrene. The compositions of the present invention be readily mixed and processed on conventional equipm such as extruders, Banburys, two-roll mills, and like, do not cause mold fouling, and are non-bloomi Blending takes place at a temperature generally ab the melting point of HIPS such as from about 250°F about 500°F. The blends of the present invention can cont various conventional additives in conventional amounts known to the art as well as to the literature. example, the HIPS can contain various conventional ult violet light inhibitors, various lubricant agents such calcium stearate, and the like. Additives which generally utilized due to their low cost and effect flame retarding properties are various antimony b synergists, equivalences thereof, derivatives there and the like, with a typical example being antim trioxide. The amount of antimony base synergists generally based upon the amount of brominated polystyr and generally ranges from about 1 part for every 2 t parts by weight of the brominated polystyrene. various additives and flame retardants such as antim trioxide can either be added directly to the HIPS blended therewith and subsequently this mixture blen with the low molecular weight brominated polystyrenes alternatively, added to and blended with the low mole lar weight brominated polystyrenes and subsequent blended with the HIPS. The blends of the present inve tion generally have a flame retardance of VO at 1/8 in UL-94. Generally, any conventional mixing device can utilized such as an extruder, a Banbury, a two-roll mil or the like. The blends of the present invention can utilized wherever flame retardancy HIPS is desired su as for small appliances, television cabinets, comput housings, and the like. The invention will be better understood reference to the following examples. EXAMPLES Test Procedures for Examples ASTM TE METflQ Tensile Strength (psi) D-638 Elongation at Break (%) D-638 Flex Strength (psi) D-790 Tangent Modulus x 10 5 (psi) D-790 Notched Izod 1/8" (ft-lb/in) D-256 Reverse Izod 1/8" (ft-lb/in) D-256 Gardner Impact (in-lbs) D-302 UL 94 1/8" Bars UL 94 Oxygen Index D-286 Footnotes for Examples 1 through 8 PS Polystyrene DP Degree of polymerization which specifies t polymer chain length by the number of repeati units in the chain. Pyro Chek 68 PB A brominated polystyrene having a DP * 2,0 and typically a bromine content of about 66.5 percent weight. EXAMPLE 1 High Impact PS (Huntsman 3037) 95 80 83 82 80 Calcium Stearate 1 1 1 1 1 Sb 2 θ3 4 4 4 4 4 Pyro Chek 68 PB _ 15 β Decabromodiphenyloxide 12 1 r 2-Bis(tetrab-_omophthe_li_nido) ethane 13 Brαninated PS (DP 13) - - - - 15 Tensile Strength (psi) 4800 4700 5000 4600 4900 Elongation at Break (%) 81 13 11 44 66 Flexural Strength (psi) 9600 9400 10000 9000 9800 Tangent Modulus x 10 5 (psi) 3.6 3.9 3.7 3.9 3.8 Notched Izod (ft-lb/in) 1.7 0.6 1.4 0.9 1.1 Reverse Izod 1/8" (ft-lb/in) 12.0 2.7 9.0 6.0 8.0 Gardner Impact (in-lbs) 18 3 6 6 5 UL941/8" Bars Fail Fail V-l V-O V-O Oxygen Index 19.6 23.8 25.4 25.2 24.9 EXAMPLE 2 A B C D E F G High Impact PS (Huntsman 3037) 100 81 81 81 81 81 81 Sb 2 θ3 Pyro Chek 68 PB - 15 - - - - Brominated PS (DP6) 15 Brominated PS (DP8) 15 Brominated PS (DP13) __. - - - 15 - Brαninated PS (DP20) _ _. - - - 15 Brominated PS (DP40) _ - _ -. - - 15 Tensile Strength (psi) 4100 4500 3400 3100 4000 4300 4300 Elongation Break (%) 39.0 7.2 4.0 3.6 4.1 4.2 5.5 Flex Strength (psi) 9500 9300 8800 9000 9300 8600 8700 Tangent Modulus x 10 5 (psi) 3.3 3.4 3.4 3.2 3.4 3.6 3.4 Notched Izod 1/8" UL 941/8" Bars Fail V-O V-O V-O V- V-O V-O EXAMPLE 3 B High Impact PS (Huntsman 3037) 100 81 84 81 81 Sb2θ 3 - 4 4 4 4 Pyro Chek 68 PB - 15 - - - Dec^romcdiphenyloxide - - 12 - - Brominated PS (DP13) — - - 15 - Brominated PS (DP8) - - - - 15 Tensile Strength (psi) 4540 4556 4553 4455 3890 Elongation at Break (%) 47.7 6.8 4.9 5.1 4.0 Flex Strength (psi) 9830 9661 10218 9906 9865 Tangent Modulus xlO 5 (psi) 3.2 3.5 3.5 3.4 3.3 Notched Izod 1/8" (ft-lb/in) 1.6 0.58 1.2 0.97 ' 1.1 Reverse Izod 1/8" (ft-lb/in) 13.4 2.6 8.5 7.2 8.6 Gardner Impact (in-lbs) 30 3.0 7.0 4.0 5.0 UL 941/8" Bars Fail V-O V-O V-O V-O EXAMPIE 4 B E High Irrpact PS (Huntsman 3037) 100 84 81 81 81 Sb2θ 3 4 4 4 4 Decabromodiphenyloxide 12 „ _ _ Pyro Chek 68 PB 15 Brominated PS (DP13) 15 Brominated PS (DP9) 15 Tensile Strength (psi) 4720 5090 4230 4630 4500 Elongation at Break (%) 44 7.0 5.7 6.2 5.2 t Flex Strength (psi) 9960 10700 9740 10470 9830 Tangent Modulus xlO 5 (psi) 3.41 3.73 3.70 3.71 3.70 Notched Izod 1/8" (ft-lb/in) 1.8 1.4 0.7 0.9 1.5 Reverse Izod 1/8" (ft-lb/in) 11.4 7.5 2.0 8.4 8.5 UL 941/8" Bars Fail V-O V-O V-O V-O Oxygen Index 18.0 26.7 23.4 25.8 26.5 A B C D E High Iπ act PS (Am. Hoechst 840) 100 84 81 81 81 SD2O3 - 4 4 4 4 Decabromodiphenyloxide _ 12 Pyro Chek 68 PB 15 Brominated PS (DP13) 15 Brominated PS (DP9) — — — - 15 Tensile Strength (psi) 3520 3740 3430 3820 3890 Elongation at Break (%) 65 82 22 62 63 Flex Strength (psi) 7550 7600 7360 7870 8420 Tangent Modulus xlO 5 (psi) 3.41 3.73 3.63 3.70 3.73 Notched Izod 1/8" (ft-lb/in) 3.4 2.4 1.0 2.3 2.1 Reverse Izod 1/8" (ft-lb/in) 14.3 11.7 2.2 11.1 10.2 UL 941/8" Bars Fail V-O V-O V-O V-O Oxygen Index 17.5 26.7 23.8 25.0 26.3 EXAMPLE 6 • High Impact PS (Dow Styron 498) 100 96 84 81 81 SD2O3 - 4 4 4 4 Dec-abromodiphenyloxide - - 12 - - Pyro Chek 68 PB - - - 15 - Brominated PS (DP8) - - - - 15 Tensile Strength (psi) 4250 4290 4530 4270 4340 Elongation at Break (%) 61 69 33 10 11 Flex Strength (psi) 9340 9110 9780 9390 9820 Tangent Modulus xlO 5 (psi) 3. 67 3.76 3.87 4.09 3.86 Notched Izod 1/8" (ft-lb/in) 2. 0 1.8 1.1 0.5 0.9 Reverse Izod 1/8" (ft-lb/in) 7. 1 6.8 5.9 1.9 5.5 Gardner Impact (in-lbs) 9. 8 7.2 4.2 <2 2.8 UL 941/8" Bars Fail Fail V-O V-O V-O EXAMPLE 7 High Impact PS (Dow Styron 498) 100 96 84 81 81 Sb 2 θ3 - 4 4 4 4 Decabromodiphenyloxide - - 12 - - Pyro Chek 68 PB - - - 15 - Brominated PS (DP8) - - - - 15 Tensile Strength (psi) 3420 3320 3490 3500 3610 Elongation at Break (%) 80 63 70 26 38 Flex Strength (psi) 7350 7340 7710 7420 7850 Tangent Modulus xlO 5 (psi) 3.42 3.5 3.76 3.73 3.54 Notched Izod 1/8" (ft-lb/in) 2.1 2.0 1.5 0.6 1.2 Reverse Izod 1/8" (ft-lb/in) 10.5 9.7 6.1 1.9 6.5 Gardner Impact (in-lbs) 21 13 5.2 ■2.7 3.0 UL 941/8" Bars Fail Ffcil V-O V-O V-O The various Examples generally demonstrate th property retention is much better with a low molecul weight brominated polystyrene as opposed to a hi molecular weight polystyrene such as Pyro Chek 68 P Example 2 generally demonstrates that as the degree polymerization of the brominated polystyrene is increa ed, the physical property retentions such as notched Iz decreases. Examples 3 through 7 show good proper retention using the low molecular weight brominat polystyrenes of the present invention as compared to high molecular weight brominated polystyrene as well that good property retention is obtained utilizing variety of high impact polystyrenes made by differe manufacturers. While in accordance with the Patent Statute the best mode and preferred embodiment has been s forth, the scope of the invention is not limited theret but rather by the scope of the attached claims.

Claims: WHAT IS CLAIMED IS: 1. A flame retarded high impact resist polystyrene, comprising: a high impact resistant polystyrene, an effective amount of a low molecular wei brominated polystyrene to provide physical prope retention, and an antimony base synergist in an amount about 1 part by weight for every about 2 to about 5 pa by weight of said brominated polystyrene. 2. A flame retarded high impact resist polystyrene according to Claim 1, wherein said molecular weight polystyrene has a degree of polymeri tion of from about 3 to about 20. 3. A flame retarded high impact resist polystyrene according to Claim 2, wherein said halogen bromine, wherein the amount of said bromine is from ab 53 percent to about 76 percent by weight based upon total weight of said low molecular weight polystyre and wherein the amount of said low molecular wei brominated polystyrene is from about 3 percent to ab 20 percent by weight based upon the total weight of s brominated polystyrene and said high impact resist polystyrene. 4. A flame retarded high impact resist polystyrene according to Claim 3, wherein the amount said low molecular weight brominated polystyrene is f about 10 percent to about 18 percent by weight, whe the amount of said bromine is from about 61 percent about 71 percent by weight, and wherein said degree polymerization is from about 5 to about 15. 5. A flame retarded high impact resista polystyrene according to Claim 4, wherein said degree polymerization is from about 6 to about 12. 6. A flame retarded, high impact polystyre composition, comprising: a blend of a high impact polystyrene and effective amount of a low molecular weight brominat polystyrene to provide said blend with a flame retardan of VO at 1/8 inch in UL-94. 7. A flame retarded, high impact polystyre composition according to Claim 6, wherein said l molecular weight brominated polystyrene has a degree polymerization of from about 3 to about 20, and where the amount of said bromine in said polystyrene is fr about 53 percent to about 76 percent by weight. 8. A flame retarded, high impact polystyr composition according to Claim 7, wherein said degree polymerization is from about 5 to about 15. 9. A flame retarded, high impact polystyr composition according to Claim 8, wherein the amount said bromine is from about 61 percent to about 71 perc by weight, and wherein said degree of polymerization from about 6 to about 12. 10. A flame retarded, high impact polystyr composition according to Claim 9, wherein the amount said bromine is from about 66 percent to about 70 perc by weight. 11. A high impact resistant polystyrene c position, comprising: a blend of a high impact polystyrene, a suf cient amount of a low molecular weight brominated po styrene to provide effective property retention, and an antimony base synergist in an amount about 1 part by weight for every about 2 to about 5 pa by weight of said brominated polystyrene. 12. A high impact resistant polystyrene com sition according to Claim 11, wherein said suffici amount of said low molecular weight brominated styrene from about 3 percent to about 20 percent by weight ba upon the total weight of said high impact polystyrene said low molecular weight brominated polystyrene, wher said brominated polystyrene has a degree of polymeri tion of from about 3 to about 20, and wherein the amo of said bromine in said oligomer is from about 53 perc to about 76 percent by weight. 13. A high impact resistant polystyrene c position according to Claim 12, wherein the amount said low molecular weight brominated polystyrene oligo is from about 10 percent to about 18 percent by weight 14. A high impact resistant polystyrene com sition according to Claim 13, wherein said degree polymerization is from about 5 to about 15, and wher the amount of bromine in said oligomer is from about percent to about 71 percent by weight. 15. A high impact resistant polystyrene co sition according to Claim 14, wherein said degree polymerization is from about 7 to about 9, and whe the amount of said bromine is from about 66 percent about 70 percent by weight. 16. A high impact resistant polystyrene comp sition according to Claim 11, wherein said proper retention is retained by increasing the amount of brom nation of said brominated polystyrene with a correspon ing decrease in the degree of polymerization thereof. 17. A high impact resistant polystyrene co position according to Claim 12, wherein said proper retention is retained by increasing the amount of brom nation of said brominated polystyrene with a correspon ing decrease in the degree of polymerization thereof. 18. A high impact resistant polystyrene comp sition according to Claim 14, wherein said proper retention is retained by increasing the amount of bro nation of said brominated polystyrene with a correspo ing decrease in the degree of polymerization thereof. 19. A process for making a flame retard high impact polystyrene composition, comprising the st of: melt blending a high impact polystyrene with effective amount of a low molecular weight bromina polystyrene and an antimony base synergist in an amo of about 1 part by weight for every about 2 to about parts by weight of said low molecular weight bromina polystyrene to provide a composition having good g flame retardancy and good physical retention of notc Izod. 20. A process according to Claim 17, wher the amount of bromine in said polystyrene based upon total weight of said brominated polystyrene is from ab 53 percent to about 76 percent by weight. 21. A process according to Claim 18, wher the degree of polymerization of said brominated po styrene is from about 3 to about 20, and wherein amount of said bromine is from about 61 percent to ab 71 percent by weight. 22. A process according to Claim 19, wher said degree of polymerization is from about 6 to ab 12.

Inventors: DEVER JAMES L, GILL JAMES C, DEVER, JAMES, L., GILL, JAMES, C.
Applicants: FERRO CORP, FERRO CORPORATION
Application year: 1990
Main classification: C09K21
IPC codes: C08K3, C08L25, C08L51, C09K21