Flame retardant agent for thermoplastic resin and flame retardant resin composition

Abstract

A flame retardant agent for a thermoplastic resin, which enables the thermoplastic resin containing the flame retardant agent to keep its viscous property, to be made into a fiber readily, and to exhibit flame retardant effect even when ammonium dihydrogen phosphate is contained in the flame retardant agent as a non-halogen flame retardant component. Also disclosed is a flame retardant resin composition containing the flame retardant agent. Specifically, the flame retardant agent for a thermoplastic resin comprises ammonium dihyrogen phosphate, potassium hydroxide, glycerin and urea, wherein potassium hydroxide is contained in an amount of 10 to 70 parts by weight, glycerin is contained in an amount of 0.1 to 4.0 parts by weight, and urea is contained in an amount of 1 to 9 parts by weight relative to 100 parts by weight of ammonium dihydrogen phosphate.

Description

FIELD OF THE ART[0001]The present invention relates to a flame retardant agent for a thermoplastic resin and a flame retardant resin composition obtained by adding the flame retardant agent for a thermoplastic resin to a thermoplastic resin.BACKGROUND ART[0002]As is well known, halogen compounds and phosphorus / nitrogen compounds exhibit a conspicuous flame retardant effect, and are often used as a flame retardant agent of a thermoplastic resin.[0003]Also, the above described flame retardant agent is essential in a recycling process in which used PET (polyethylene terephthalate) bottles are crushed, washed, and made into source materials again to form polyester fibers. Currently, halogen flame retardant agents made of a bromine compound or a chlorine compound are widely used.[0004]Also, for example, Japanese Patent Application Laid-Open (JP-A) No. 2004-263188 discloses ammonium dihydrogen phosphate as one of the choices for a phosphorus / nitrogen flame retardant component.[0005]The af...

AI Technical Summary

Benefits of technology

[0019]According to the present invention, ammonia is volatilized by adding at least potassium hydroxide to ammonium dihydrogen phosphate, so that one can obtain a flame retardant agent in which, even if it is used in a thermoplastic resin, the physical properties of the thermoplastic resin is not deteriorated. Also, since a flame retardant agent obtained by blending potassium hydroxide with ammonium dihydrogen phosphate is added to a thermoplastic resin, resulting resin satisfies an IV value capable of forming fibers, and also a flame retardant effect is obtained, whereby a flame retardant resin composition that can be easily made into fibers can be obtained.

[0020]Here, the present inventors infer as follows. In the present invention, in accordance with increase in the amount of added KOH, NH4H2PO4 reacts and successively changes to NH4KHPO4, to K2HPO4, and to K3PO4, and a mixture of these chemical species constitute a major component of the flame retardant agent, and also a double decomposition proceeds in parallel. Therefore, including the chemical species that are present in a slight amount, a mixture having a composition of (NH4)nKmHpPO4 (n or m=0 to 3, p=0 to 2) will be present, and the (NH4)nKmHpPO4 composition mixture is formed as a particulate crystal that can be easily kneaded, and has a melting point at around the melting temperature of a PET resin, so that it is dispersed and liquefied in a kneading process with the PET resin. Also, K3PO4 that is partly generated has a melting point having a further higher melting point exceeding 1000° C., so that it contributes to an improvement in the viscosity of the whole, whereby the dispersion or dissolution proceeds with a further higher homogeneity, and a flame retardant effect is obtained.

Problems solved by technology

The aforesaid conventional halogen flame retardant agent is excellent in a flame retardant effect; however, it raises a problem in that the fibers and the like that are made flame retardant by the halogen flame retardant agent give rise to a cause of generating harmful gases or dioxins at the time of burning.

However, with this amount of addition, there raised a problem in that the physical properties of the PET resin decrease and a problem of giving negative effects in a process of forming the PET resin into fibers by deterioration in the physical property.

Inherently, a thermoplastic resin such as polyethylene terephthalate has a poor compatibility with mingled foreign substances, and hence the molecular weight decreases because the molecular chains are cut by hydrolysis or thermal decomposition.

Due to this physical property deterioration, the thermoplastic resin loses its viscosity and hence cannot be drawn and extended in a thread form.

Namely, when kneading is carried out after a flame retardant agent is added into a thermoplastic resin, a flame retardant agent having poor dispersibility increases the ratio of the parts where the flame retardant agent is absent, whereby the flame retardant effects are hardly exhibited, and the product will be liable to catch fire.