Injection molded article and method for the manufacture thereof
View Patent ↗The molding defect known as “splay” is reduced in poly(arylene ether) injection molding compositions including specific amounts of poly(arylene ether), rubber-modified polystyrene, triaryl phosphate, and aryl phosphite. The molding compositions are particularly useful for injection molding articles with large, thin sections, such as battery cases for the back-up batteries used in wireless towers.
1. A method of reducing splay in an injection molded article comprising a poly(arylene ether) composition, the method comprising:
injection molding a poly(arylene ether) composition to form an injection molded article; wherein the injection molding comprises filling a barrel of an injection molding machine with the poly(arylene ether) composition and emptying at least 80 weight percent of the barrel to mold a single injection molded article;
wherein a portion of the injection molded article comprises
a first dimension of at least 10 centimeters,
a second dimension of at least 10 centimeters, and
a third dimension of less than 1 centimeter;
wherein the poly(arylene ether) composition comprises
45 to 65 weight percent of a poly(arylene ether) having an intrinsic viscosity of 0.3 to 0.55 deciliter/gram measured at 25° C. in chloroform,
15 to 35 weight percent of a rubber-modified polystyrene, wherein the rubber-modified polystyrene comprises polystyrene and polybutadiene,
5 to 25 weight percent of a triaryl phosphate that is a liquid at one atmosphere and at least one temperature in the range 25 to 50° C., and
0.1 to 1 weight percent of an aryl phosphite having the structure P(OR 1 ) 3 , wherein each occurrence of R 1 is independently C 1 -C 24 hydrocarbyl, provided that at least one occurrence of R 1 is an unsubstituted or substituted C 6 -C 24 aryl;
wherein all weight percents are based on the total weight of the poly(arylene ether) composition.
2. The method of claim 1 , wherein each occurrence of R 1 is independently an unsubstituted or substituted C 6 -C 24 aryl.
3. The method of claim 1 , wherein the aryl phosphite comprises tris(2,4-di-tert-butylphenyl)phosphite.
4. The method of claim 1 , wherein the poly(arylene ether) composition further comprises 0.5 to 5 weight percent of an unhydrogenated block copolymer of an alkenyl aromatic monomer and a conjugated diene.
5. The method of claim 1 , wherein the poly(arylene ether) composition comprises 5 to 50 weight percent of recycled content.
6. The method of claim 5 , wherein the recycled content comprises material that has been recycled 1 to 10 times.
7. The method of claim 5 , wherein the injection molded article is a case for a lead-acid battery; and wherein the recycled content comprises 0.1 to 2 weight percent lead based on the weight of the recycled content.
8. The method of claim 5 , wherein the injection molded article is a case for a lead-acid battery; and wherein the poly(arylene ether) composition comprises 0.1 to 2 weight percent lead based on the total weight of the poly(arylene ether) composition.
9. The method of claim 1 , wherein the poly(arylene ether) composition excludes polyamides.
10. The method of claim 1 , wherein the poly(arylene ether) composition excludes polyesters.
11. The method of claim 1 , wherein the poly(arylene ether) composition excludes polyolefins.
12. The method of claim 1 , wherein the poly(arylene ether) composition excludes alpha-olefin/hindered vinylidene monomer interpolymers.
13. The method of claim 1 , wherein the poly(arylene ether) composition excludes hydrogenated block copolymers of an alkenyl aromatic compound and a conjugated diene.
14. The method of claim 1 , wherein the poly(arylene ether) composition excludes homopolymers of alkenyl aromatic monomers.
15. The method of claim 1 , wherein the poly(arylene ether) composition excludes rubber-modified polystyrenes comprising hydrogenated polybutadiene.
16. The method of claim 1 , wherein the poly(arylene ether) composition excludes homopolymers of alkenyl aromatic monomers and rubber-modified polystyrenes comprising hydrogenated polybutadiene.
17. The method of claim 1 , wherein the poly(arylene ether) composition excludes aromatic amines.
18. The method of claim 1 , wherein the poly(arylene ether) composition excludes fillers.
19. The method of claim 1 ,
wherein a portion of the injection molded article comprises a first dimension of at least 30 centimeters and a second dimension of at least 20 centimeters;
wherein the poly(arylene ether) composition comprises
50 to 58 weight percent of the poly(arylene ether), wherein the poly(arylene ether) comprises a poly(2,6-dimethyl-1,4-phenylene ether);
21 to 29 weight percent of the rubber-modified polystyrene,
14 to 20 weight percent of the triaryl phosphate, wherein the triaryl phosphate comprises bisphenol A bis(diphenyl phosphate), and
0.3 to 0.5 weight percent of the aryl phosphite; and
wherein the poly(arylene ether) composition further comprises 1 to 2.5 weight percent of an unhydrogenated block copolymer of an alkenyl aromatic monomer and a conjugated diene.
20. An injection molded article prepared by the method of claim 1 .
21. The injection molded article of claim 20 , wherein injection molded article is a battery case.
22. The injection molded article of claim 20 , wherein the injection molded article is a case for a lead-acid battery.
23. The injection molded article of claim 22 , wherein the poly(arylene ether) composition comprises 0.1 to 2 weight percent lead based on the total weight of the poly(arylene ether) composition.