JPS6255544B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to flame-retardant thermoplastic resin compositions. Conventionally, a polymer composition obtained by graft polymerizing styrene and acrylonitrile to an acrylic acid alkyl ester polymer (hereinafter abbreviated as AAS resin)
A resin composition comprising a polyvinyl chloride resin and a vinyl chloride resin is known as a composition having excellent impact resistance, weather resistance, and flame retardancy. However, this composition has a low heat distortion temperature of vinyl chloride resin, so the base AAS
Compared to resin, it had the disadvantage of lower heat deformation resistance. Furthermore, if glass fiber or a resin reinforced with glass fiber is mixed in order to improve heat resistance, the heat resistance will certainly improve, but the appearance of the molded product will be impaired. The present invention solves these problems and relates to a flame-retardant thermoplastic resin composition that has improved heat shrinkage and heat deformation resistance under low loads, particularly in heat deformation resistance. That is, the present invention grafts at least one monomer selected from aromatic vinyl compounds, vinyl cyanide compounds, and methacrylic acid esters to [A] vinyl chloride resin and [B] acrylic acid alkyl ester polymer. A polymer composition obtained by polymerizing [C] polyalkylene terephthalate and [D] magnesium silicate powder in a weight ratio of [A]/[B] of 40/60 to 70/30,
[C]/([A]+[B]) has a weight ratio of 5/100 to 30/
100 and [D]/([A]+[B]) in a weight ratio of 2/100 to 20/100. [A] Component vinyl chloride resin is a vinyl chloride homopolymer, a copolymer of vinyl chloride and other vinyl monomers such as ethylene, vinyl acetate, vinylidene chloride, etc. In the case of a copolymer, vinyl chloride The content is preferably 90% by weight or more in terms of flame retardancy and fluidity. Also, post-chlorinated vinyl chloride resins may be used. Component [B] of the present invention is obtained by graft polymerizing an aromatic vinyl compound, a vinyl cyanide compound, or a methacrylic acid ester to an acrylic acid alkyl ester polymer serving as a rubber component. The monomers used in the production of the acrylic acid alkyl ester polymer that becomes the rubber component include acrylic acid-
n-butyl is particularly suitable, but ethyl acrylate, propyl acrylate, hexyl acrylate,
1-13 carbon atoms such as 2-ethylhexyl acrylate
All those having 2 alkyl groups can be used alone or in combination. In addition, this acrylic acid alkyl ester polymer must be a cross-linked polymer; if a non-cross-linked polymer is used, only molded products with low impact resistance and poor appearance will be obtained. . In order to introduce cross bonds into this acrylic acid alkyl ester polymer, a polyfunctional monomer having two or more functional groups copolymerizable with the acrylic acid alkyl ester is copolymerized. This yields acrylic rubber with excellent rubber elasticity. As this polyfunctional monomer, polyvalent vinyl compounds and polyvalent allyl compounds such as triallyl cyanurate, triallylisocyanurate, divinylbenzene, triacryl formal, and ethylene glycol dimethacrylate are effective. Allyl isocyanurate and triallyl cyanurate are the best. The appropriate amount of this polyfunctional monomer to be added is 0.5 to 10% by weight; if it is less than 0.5% by weight, a sufficient degree of crosslinking will not be obtained, and if it exceeds 10% by weight, the degree of crosslinking will be excessive. It tends not to be able to impart impact resistance. Monomers to be graft-polymerized to this acrylic acid alkyl ester polymer include styrene, α-methylstyrene, vinyltoluene, etc. as aromatic vinyl compounds, and acrylonitrile, methacrylonitrile, etc. as vinyl cyanide compounds. Examples of methacrylic esters include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate,
Examples include 2-ethylhexyl methacrylate. In particular, styrene is effective as an aromatic vinyl compound, and acrylonitrile is effective as a vinyl cyanide compound. The composition of the monomer to be graft-polymerized is 100% by weight or less of an aromatic vinyl compound, especially
70-80% by weight, vinyl cyanide compounds up to 40% by weight, especially 30-20% by weight, methacrylic acid esters
It is preferable to use it so that the total amount is 100% by weight or less. The aromatic vinyl compound is preferably used in an amount of 70 to 80% by weight in order to achieve a well-balanced flowability (molding processability), heat deformation resistance, and impact resistance. When producing the polymer composition of component [B], it is preferable that the above-mentioned acrylic acid alkyl ester polymer is used in an amount of 20 to 50% by weight. If it is less than 20% by weight, sufficient impact resistance cannot be obtained, and if it exceeds 50% by weight, it is difficult to obtain a polymer powder that can be uniformly dispersed with the vinyl chloride resin. The polymerization method for producing the above-mentioned acrylic acid alkyl ester polymer and the polymer composition of component [B] is not particularly limited, and may be produced by a known method. For example, an acrylic acid alkyl ester polymer can be produced by emulsion polymerization, a graft monomer can be added to the obtained latex, and then it can be produced by emulsion-suspension polymerization. As the polyalkylene terephthalate of component [C], polybutylene terephthalate is most suitable, but other examples include polyethylene terephthalate and polypropylene terephthalate. These polymers also include those in which isophthalic acid or 2,6-naphthalene dicarboxylic acid is used as one of the acid components, and 1,4-dimethylolcyclohexane is used as one of the alcohol components. The magnesium silicate powder of component [D] includes not only pure products but also those obtained by crushing naturally occurring so-called talc into fine particles. The blending ratio of each component to obtain the desired resin composition by mixing the above components is as follows. The mixing ratio of the vinyl chloride resin as component [A] and the polymer composition as component [B] is 40/60 to 70/30 in weight ratio [A]/[B]. [A]/[B] is 40/
If it is less than 60, flame retardancy will decrease, so it is not preferable.
Moreover, if it exceeds 70/30, heat resistance and impact resistance will decrease. The mixing ratio of polyalkylene terephthalate as component [C] is 5 to 30 parts by weight based on 100 parts by weight of the total amount of components [A] and [B]. If it is less than 5 parts by weight, a sufficient effect of improving heat resistance is not observed, and
If it exceeds 30 parts by weight, moldability deteriorates, which is not preferable. In addition, the blending ratio of magnesium silicate as component [D] is the total amount of components [A] and [B] 100
The amount is 2 to 20 parts by weight. If it is less than 2 parts by weight, the effect of improving heat resistance will be small, and if it exceeds 20 parts by weight, it will deteriorate the impact resistance and adversely affect the appearance of the molded product, which is undesirable. The composition of the present invention can be prepared by mixing the predetermined components using, for example, a mixer, and then passing the mixture through a conventional kneading machine such as an extruder, Banbury, or hot roll. In this case, it is preferable to mix the [C] and [D] components after kneading the [A] and [B] components. Furthermore, at this time, additives such as stabilizers, lubricants, plasticizers, pigments, etc. may be added as necessary, and flame retardants such as antimony trioxide may also be added to improve flame retardancy. can. For further details, specific examples will be explained in Examples. Note that parts and percentages shown in the examples are parts by weight and percentages by weight, respectively, unless otherwise specified.
represents. Further, the characteristic values in the examples were determined in accordance with the following. (1) Heat shrinkage rate and heat deformation rate A JIS No. 1 tensile test piece was placed on a support plate at both ends with a gap of 10 cm, and after heat treatment at a predetermined temperature, the heat shrinkage rate and heat deformation rate were measured. (2) Izot impact strength: ASTM D 256 (3) Tensile strength: JIS K 6301 (4) Workability The fluidity during molding and the surface appearance of the molded product were visually evaluated. Examples 1 to 10 Crosslinkers obtained by emulsion polymerization of 40 to 70 parts by weight of polyvinyl chloride (hereinafter abbreviated as PVC) with a degree of polymerization of 800, 1% by weight of triallyl isocyanurate, and 99% by weight of n-butyl acrylate A polymer composition (hereinafter referred to as ,
AAS) 60 to 30 parts by weight, unreinforced polybutylene terephthalate (Mitsubishi Rayon Co., Ltd. trade name, Tuffpet N1000) 5 to 30 parts by weight, and talc (Hayashi Kasei Kogyo Co., Ltd. trade name, Micron White #5000) Table 1 shows the results of studies using various blending ratios of 2 to 20 parts by weight. Comparative Examples 1-2 The same procedures as Examples 1-10 were carried out using the formulations shown in Table 1 (polybutylene terephthalate was not blended). The characteristics are shown in Table 1. Comparative Examples 3-4 The same procedures as Examples 1-10 were carried out using the formulation shown in Table 1 (without mixing talc). The characteristics are shown in Table 1. Comparative Examples 5-6 The formulations shown in Table 1 (PVC, AAS, and glass fiber-reinforced polybutylene terephthalate were mixed) were mixed and pelletized according to Examples 1-10. The characteristics are shown in Table 1. Compared with Examples 4 and 7 in which talc was added to glass-unreinforced polybutylene terephthalate, the heat deformation resistance was slightly better, but the appearance of the molded product was inferior.

[Table] The flame-retardant resin composition according to the present invention has significantly superior heat deformation resistance by using polyalkylene terephthalate and magnesium silicate in combination, without damaging the appearance of the molded product, unlike reinforcement with glass fiber. . This effect is particularly noticeable in heat shrinkability and heat deformation resistance under low loads.

Claims (1)

[Scope of Claims] 1 [A] vinyl chloride resin, [B] acrylic acid alkyl ester polymer and aromatic vinyl compound,
A polymer composition obtained by graft polymerizing at least one monomer selected from vinyl cyanide compounds and methacrylic acid esters, [C]
Polyalkylene terephthalate and [D] magnesium silicate powder in [A]/[B] weight ratio
40/60~70/30, [C]/([A]+[B]) is 5/100~30/100 and [D]/([A]+
A flame-retardant thermoplastic resin composition containing [B]) in a weight ratio of 2/100 to 20/100.