Polyacetal resin composition and molding thereof

Abstract

A polyacetal resin composition comprising 100 parts by mass of polyacetal resin (A) whose formaldehyde emission exhibited when heated in nitrogen atmosphere at 200 DEG C for 50 min is 100 ppm or less and 0.01 to 5 parts by mass of hydrazide compound (B). From this polyacetal resin composition, despite molding conditions and molding method such that the molding temperature is high or partially the resin temperature is raised, there can be provided a molded article of strikingly low formaldehyde release. Thus, the polyacetal resin composition is applicable to a wide variety of molding conditions and molding methods. The amount of formaldehyde released from the obtained molded article is reduced to a hitherto unattained level of 1 mg / kg as measured in accordance with the method VDA275, so that the molded article can be used in various application fields wherein low VOC is demanded.

Description

technical field [0001] The present invention relates to polyacetal resin compositions which provide articles with significantly reduced formaldehyde emissions. Specifically, the present invention relates to a polyacetal resin composition which can be molded by various molding methods under a wide range of molding conditions (molding temperature, etc.), and has good heat aging resistance. technical background [0002] Polyacetal resin has a good balance of mechanical strength, chemical resistance, and sliding properties, and has excellent processability, so it is widely used in various applications such as electrical equipment and its parts, automobile parts, and other mechanical parts. [0003] Recently, there is an increasing demand for miniaturized, thin-walled, or refined polyacetal resin products, so molding methods or molding conditions that apply heat history are often used for molding. For example, pinhole-gate molding, high-cycle molding, or molding methods for smal...

AI Technical Summary

Problems solved by technology

However, according to Patent Document 2, the hydrazide compound cannot suppress the generation of formaldehyde due to the decomposition of the polyacetal resin in the molten state

Therefore, hydrazide compounds are not suitable for the above-mentioned molding or molding that causes a partial rise in resin temperature

In addition, according to Patent Document 9, the use of the hydrazide compound may be limited depending on the application, that is, under certain conditions, hydrazine may be generated due to hydrolysis of the hydrazide compound, etc., so that depending on the combination of the compound and other additives, the use is sometimes limited

In addition, adding a large amount of hydrazide compound may cause mold deposits during molding or bleed out on the surface of the product

As mentioned above, although the hydrazide compound is excellent in inhibiting the generation of formaldehyde, there is still a problem of limited use