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;
wherein all weight percents are based on the total weight of the poly(arylene ether) composition.
2. 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 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;
wherein all weight percents are based on the total weight of the poly(arylene ether) composition;
wherein the poly(arylene ether) composition comprises 5 to 50 weight percent of recycled content;
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.