JP2002012752A - Thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition which achieves the reduction of a mold shrinkage rate and the saving of the weight, of a product without impairing such inherent characteristics of a polybutylene terephthalate as the mechanical properties and flowability. SOLUTION: The thermoplastic resin composition contains resin components comprising 95-10 wt.% of (A) a polybutylene terephthalate resin; 4-50 wt.% (B) a rubber-modified polystyrene resin; and 1-40 wt.% of (C) an aromatic polycarbonate resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition having excellent mechanical properties such as moldability, strength and impact resistance, and providing a lightweight and inexpensive molded article.

[0002]

2. Description of the Related Art Thermoplastic polyester resins represented by polybutylene terephthalate resin and polyethylene terephthalate resin are easy to process, have mechanical properties, heat resistance,
Due to its excellent physical and chemical properties, it is widely used in the fields of automobile parts, electric and electronic equipment parts, and other precision equipment parts. In particular, polybutylene terephthalate resin is suitable for injection molding applications because of its high crystallization speed.

However, on the other hand, since polybutylene terephthalate resin is a crystalline resin, the molding shrinkage is large,
There is also a problem that the specific gravity is high (1.31). On the other hand, a reduction in the molding shrinkage and a reduction in the weight are desired, and there is also a high demand for cost reduction.

There has been proposed a method of blending another resin for the purpose of reducing the molding shrinkage and reducing the weight of the polybutylene terephthalate resin. The resin to be compounded is a styrene resin represented by a polystyrene resin, an AS resin, an ABS resin, polypropylene, polycarbonate, or the like. However, in either case, the reduction in the molding shrinkage and the reduction in the weight can be achieved, but the mechanical properties are reduced and the moldability (flowability) is deteriorated.

[0005]

SUMMARY OF THE INVENTION It has been desired to achieve a reduction in molding shrinkage and a reduction in weight without impairing the essential characteristics of polybutylene terephthalate, such as mechanical properties and fluidity.

[0006]

The present inventors have conducted intensive studies to solve these problems, and as a result, melt-kneaded a polybutylene terephthalate resin with a rubber-modified polystyrene resin and an aromatic polycarbonate resin at a specific ratio. By doing so, a reduction in molding shrinkage and a reduction in weight can be achieved, and an inexpensive material can be provided.

That is, the present invention relates to a resin component comprising (A) 95 to 10% by weight of a polybutylene terephthalate resin, (B) 4 to 50% by weight of a rubber-modified polystyrene resin, and (C) 1 to 40% by weight of an aromatic polycarbonate resin. Is a thermoplastic resin composition containing:

Hereinafter, the present invention will be described in detail.

A known polybutylene terephthalate resin can be used as the (A) polybutylene terephthalate resin which is the first resin component constituting the thermoplastic resin composition of the present invention. Here, the polybutylene terephthalate resin is a polymer or copolymer having an ester group, which is composed of a dicarboxylic acid unit mainly composed of terephthalic acid and a diol unit mainly composed of tetramethylene glycol in a chain unit. Usually, it is obtained by a polycondensation reaction using a dicarboxylic acid or an ester derivative thereof and a diol as main components.

The dicarboxylic acid units other than terephthalic acid include isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid,
2,6-naphthalenedicarboxylic acid, biphenyl-2,
2'-dicarboxylic acid, biphenyl-3,3'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, bis (4,4'-carboxyphenyl) methane, anthracenedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid Alicyclic dicarboxylic acids such as aromatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and dimer acid Is mentioned.

Examples of the diol unit other than tetramethylene glycol include an aliphatic or alicyclic diol having 2 to 20 carbon atoms and a bisphenol derivative. Specific examples thereof include ethylene glycol, propylene glycol,
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, decamethylene glycol, cyclohexanedimethanol, 4,4′-dicyclohexylhydroxymethane, 4,4′-dicyclohexylhydroxypropane, ethylene oxide addition diol of bisphenol A And the like. Further, triols such as glycerin and trimethylolpropane can be used.

The polybutylene terephthalate resin (hereinafter abbreviated as PBT resin) of the present invention is preferably a polybutylene terephthalate homopolymer having terephthalic acid as a sole dicarboxylic acid unit and tetramethylene glycol as a sole diol unit. . Of course, a polybutylene terephthalate copolymer containing one or more dicarboxylic acids other than terephthalic acid as the dicarboxylic acid unit and / or one or more diols other than the above tetramethylene glycol as the diol unit may be used. However, from the viewpoint of mechanical properties and heat resistance, the proportion of terephthalic acid in the dicarboxylic acid unit is preferably at least 70 mol%, more preferably at least 90 mol%, as the thermoplastic resin composition of the present invention. It is. Similarly, the proportion of tetramethylene glycol in the diol unit is preferably 7
It is 0 mol% or more, more preferably 90 mol% or more.

The intrinsic viscosity of the PBT resin in the present invention is preferably from 0.5 to 1.5 dl / g, more preferably from 0.1 to 1.5 dl / g, as measured at 30 ° C. in a 1: 1 (by weight) mixed solvent of tetrachloroethane and phenol. 6 to 1.3 dl / g.

The rubber-modified polystyrene resin, which is the second resin component constituting the thermoplastic resin composition of the present invention,
It is a mixture of a rubbery polymer in polystyrene.
As a mixing method, a simple mechanical blending method may be used, but in order to obtain good compatibility, so-called graft copolymerization in which a styrene-based monomer or the like is graft-copolymerized in the presence of a rubbery polymer. Those obtained by prescription are even more preferred. It is also desirable to use a rubber-modified polystyrene resin (graft polymer) obtained by the above method, which is obtained by a so-called graft-blend method in which polystyrene obtained by a separate method is mixed.

The polymerization methods include emulsion polymerization, solution polymerization,
Suspension polymerization or the like can be applied. Such a rubber-modified polystyrene resin is generally a high-impact polystyrene (H
IPS).

Specific examples of the rubbery polymer include conjugated diene rubbers such as polybutadiene, styrene-butadiene copolymer, hydrogenated styrene-butadiene block copolymer, and non-polymers such as ethylene-propylene copolymer. Conjugated diene rubbers may be mentioned, and among them, polybutadiene is preferred.

The styrene monomer includes styrene, α-methylstyrene, p-methylstyrene, bromostyrene and the like, and among these, styrene and / or
Alternatively, it is optimal to use α-methylstyrene. Examples of the monomer other than the styrene-based monomer include vinyl monomers such as acrylonitrile and methyl methacrylate.

The rubber content in the rubber-modified polystyrene resin is preferably from 1 to 40% by weight, more preferably from 3 to 30% by weight. Even when a monomer component other than the styrene monomer is contained, the content of the rubber and the styrene monomer component in the rubber-modified polystyrene resin is desirably 90% by weight or more, and more desirably. 9
5% by weight or more.

The MFR reflecting the molecular weight of the rubber-modified polystyrene resin is 0.5 to 1 at 200 ° C. under a load of 5 kg.
5 g / 10 min is preferable, and more preferably 1.0 to 1
0 g / 10 minutes.

As the aromatic polycarbonate resin which is the third resin component constituting the thermoplastic resin composition of the present invention, an aromatic dihydroxy compound or a small amount of the polyhydroxy compound is reacted with phosgene or carbonate diester. And a thermoplastic aromatic polycarbonate polymer or copolymer which may be branched. As aromatic dihydroxy compounds, 2,2-bis (4-hydroxyphenyl) propane (= bisphenol A), tetramethylbisphenol A, bis (4-
(Hydroxyphenyl) -p-diisopropylbenzene,
Examples thereof include hydroquinone, resorcinol, and 4,4-dihydroxydiphenyl, and preferably include bisphenol A.

In order to obtain a branched aromatic polycarbonate resin, phloroglucin, 4,6-dimethyl-2,4,4
6-tri (4-hydroxyphenyl) heptene-2,
4,6-dimethyl-2,4,6-tri (hydroxyphenyl) heptane, 2,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptene-1,3,5-tri (4- Hydroxyphenyl) benzene, 1,1,1-
Polyhydroxy compounds represented by tri (4-hydroxyphenyl) ethane or the like, or 3,3-bis (4-hydroxyaryl) oxindole (= isatin bisphenol), 5-chlorisatin bisphenol, 5,
7-Dichloroisatin bisphenol, 5-bromoisatin bisphenol and the like may be used as a part of the aromatic dihydroxy compound. The amount used is 0.01 to 10 mol%, preferably 0.1 to 2.0 mol%, of the total aromatic dihydroxy compound.

In order to control the molecular weight, a monovalent aromatic hydroxy compound may be used, and m- and p-methylphenol, m- and p-propylphenol, p-tert
-Butylphenol and p-long-chain alkyl-substituted phenols.

The aromatic polycarbonate resin is preferably a polycarbonate resin derived from 2,2-bis (4-hydroxyphenyl) propane,
Examples include polycarbonate copolymers derived from 2-bis (4-hydroxyphenyl) propane and other aromatic dihydroxy compounds.

As the polycarbonate resin, a mixture of two or more resins may be used.

The molecular weight of the polycarbonate resin is 15,000 as a viscosity average molecular weight calculated from the solution viscosity measured at a temperature of 25 ° C. using methylene chloride as a solvent.
~ 30,000, preferably 16,000 ~ 2
5,000.

The composition ratio of the respective resin components constituting the thermoplastic resin composition of the present invention is (A) 95 to 10% by weight of polybutylene terephthalate resin, preferably 90 to 30% by weight, more preferably 80 to 50% by weight. %, (B) 4 to 50%, preferably 6 to 45%, more preferably 8 to 40% by weight of the rubber-modified polystyrene resin and (C) 1 to 40% by weight of the aromatic polycarbonate resin, preferably 2 to 4% by weight.
It is 38% by weight, more preferably 2 to 35% by weight. If the polybutylene terephthalate resin component is less than 10% by weight, the tensile (bending) strength, heat resistance, crystallinity, moldability, fluidity, etc., which are characteristics of the polybutylene terephthalate resin, are not exhibited. On the other hand, if the polybutylene terephthalate resin component exceeds 95% by weight, the effects of reducing the molding shrinkage and reducing the weight by the rubber-modified polystyrene resin and aromatic polycarbonate resin are insufficient.

The thermoplastic resin composition of the present invention contains (E)
It is preferable to add an organic phosphorus compound. (E) Examples of the organic phosphorus compound include an organic phosphate compound, an organic phosphite compound and an organic phosphonite compound, and are preferably an organic phosphate compound.

Preferred examples of the organic phosphate compound include a long-chain dialkyl acid phosphate compound represented by the formula (1).

[0029]

Embedded image

(In the formula, R ¹ and R ² each represent an alkyl group having 8 to 30 carbon atoms.) Specific examples of the alkyl group having 8 to 30 carbon atoms include an octyl group and 2-ethylhexyl. Groups, isooctyl, nonyl, isononyl, decyl, isodecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, triacontyl and the like. Specific examples of the long-chain dialkyl acid phosphate compound include dioctyl phosphate, di (2-ethylhexyl) phosphate, diisooctyl phosphate, dinonyl phosphate, diisononyl phosphate, didecyl phosphate, diisodecyl phosphate, dilauryl phosphate, ditridecyl phosphate, Examples include diisotridecyl phosphate, dimyristyl phosphate, dipalmityl phosphate, distearyl phosphate, dieicosyl phosphate, ditriacontyl phosphate, and the like. Preferably, distearyl phosphate, dipalmityl phosphate, dimyristyl phosphate is selected.

The amount of the organic phosphorus compound is 0.01 to 0.5 part by weight, preferably 0.1 to 0.5 part by weight, based on 100 parts by weight of the total amount of the resin components constituting the thermoplastic resin composition of the present invention.
It is from 0.5 to 0.3 part by weight, more preferably from 0.1 to 0.2 part by weight. If the amount is less than 0.01 part by weight, the effect of improving the heat stability and heat retention stability of the material inherently contained in the organic phosphorus compound is not exhibited. In addition, the compounding amount is 0.5
Exceeding the weight part adversely affects performance other than heating stability and retention stability. The organic phosphorus compounds may be used alone or in combination of two or more.

Various additives other than the above-mentioned organic phosphorus compounds can be added to the thermoplastic resin composition of the present invention as long as the object of the present invention is not impaired. Examples of the additive include a crystallization accelerator, an antioxidant, an ultraviolet absorber, a heat stabilizer, a lubricant, a release agent, a coloring agent including a pigment and a dye, a foaming agent, a crosslinking agent (epoxy compound, acid anhydride, Isocyanate compounds).

The thermoplastic resin composition of the present invention may contain a flame retardant for imparting flame retardancy. Flame retardants include organic halogen compounds, antimony compounds, phosphorus compounds, and other organic and inorganic compounds.

Examples of the organic halogen compound include brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, pentabromobenzyl polyacrylate and the like.

Examples of the antimony compound include antimony trioxide, antimony pentoxide, sodium antimonate and the like.

Examples of the flame retardant of the phosphorus compound include phosphoric ester, polyphosphoric acid, ammonium polyphosphate, red phosphorus and the like.

Other organic and inorganic flame retardants include nitrogen compounds such as melamine and cyanuric acid, and inorganic compounds such as aluminum hydroxide, magnesium hydroxide, silicon compounds and boron compounds.

The thermoplastic resin composition of the present invention may contain, if necessary, other thermoplastic resins (eg, polyethylene, acrylic resin, polyamide, polyphenylene sulfide resin, liquid crystal polyester resin, polyacetal, polyphenylene oxide) and thermosetting. And at least one kind of conductive resin (for example, phenol resin, melamine resin, silicone resin, epoxy resin) and the like. The method for producing the thermoplastic resin composition of the present invention is not limited to a specific method, but is preferably by melt-kneading, and a kneading method generally used for thermoplastic resins can be applied. As the kneading method, for example, if necessary, after uniformly mixing each component with a substance as an additional component using a Henschel mixer, a ribbon blender, a V-type blender, or the like, a single-screw or multi-screw extruder, a roll, It can be kneaded with a Banbury mixer, Labo Plastomill (Bradender) or the like. Each component, including additional components, may be fed to the kneader at once or sequentially. Further, a mixture of two or more components selected from each component including an additional component may be used in advance.
The molding method of the thermoplastic resin composition of the present invention is not particularly limited, and molding methods generally used for thermoplastic resins, that is, molding methods such as injection molding, hollow molding, extrusion molding, and press molding. Can be applied.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

The abbreviations and contents of the components used in the present experimental examples and comparative examples are as follows.

(1) Polybutylene terephthalate: homopolymer (manufactured by Mitsubishi Engineering-Plastics Corporation, trade name Novadur (registered trademark) 5020S and 5)
Features of 110ZS (hereinafter referred to as “PBT”) 5020S: phenol / tetrachloroethane =
50/50 (weight ratio) The intrinsic viscosity measured in a mixed solvent at 30 ° C. is 1.24.

Characteristics of 5114ZS: intrinsic viscosity is 1.1
4.

(2) High impact polystyrene: (A
& M Co., Ltd. product, trade name Dialex (registered trademark) H
T744 (hereinafter referred to as “HIPS”) Features of HT744: rubber (polybutadiene) content 8.8
% By weight, average rubber particle size 1.8 μm, number average molecular weight 92,
000, weight average molecular weight 230,000. Melt flow rate (200 ° C, 5 kgf) 1.8 g / 10 min (3) Polycarbonate: Aromatic polycarbonate produced by reacting bisphenol A with phosgene (Mitsubishi Engineering Plastics Co., Ltd. product, trade name NOVAREX (registered) (Trademark) 7022PJ 4LV (hereinafter referred to as "PC") Physical properties of 7022PJ 4LV: viscosity average molecular weight 20,0
(4) Organic phosphate compound: ADK STAB AX-71 manufactured by Asahi Denka (mainly composed of distearyl phosphate) (hereinafter referred to as “AX-71”) The thermoplastic resin composition of the present invention is prepared by subjecting various test pieces to injection molding. Molded. Molding was performed at a cylinder temperature of 250 to 260 ° C and a mold temperature of 50 ° C. The physical property evaluation test of the resin composition was performed by the following method.

(A) Tensile strength, tensile elongation at break: AST
A tensile test of ASTM D-638 was performed using a tensile test piece prepared in accordance with M standard D-638. The tensile strength is expressed in units of MPa. The tensile elongation at break is a value between chucks and is expressed in units of%.

(B) Flexural strength and flexural modulus: ASTM
ASTM D-790 bending test was performed using a bending test piece prepared according to the standard D-790. The flexural strength is expressed in MPa and the flexural modulus is expressed in GPa.

(C) Izod impact value: ASTM standard
ASTM D-25 using Izod impact test specimens (notched, 3.2 mm width) made according to D-256.
A 6 Izod impact test (1/8 inch width) was performed.
Izod impact values are expressed in units of J / m.

(D) Specific gravity: The specific gravity of the Izod impact test piece was measured. Specific gravity was calculated from the weight in air and the weight in water using Archimedes' principle.

(E) Mold shrinkage: thickness 2 mm, length 10
A square plate of 0 mm x 100 mm width is injection molded with a film gate mold, and the flow direction (MD) and the direction perpendicular to the flow (TD).
Was measured for molding shrinkage. The molding shrinkage is expressed in units of%.

(F) Melt viscosity: The melt viscosity (shear rate dependence) at a resin temperature of 270 ° C. was measured using a Capillograph (model: 1C) manufactured by Toyo Seiki. Shear rate 60
The melt viscosity at 80 sec ⁻¹ is expressed in Pa · s. [Examples 1 to 5] The components and the mixing ratios shown in Table 1 were sufficiently mixed and stirred, and then supplied to a twin-screw extruder (trade name: TEX30C) manufactured by Nippon Steel Corporation with a vent port. The pressure was reduced to 600 Torr from the vent port installed downstream of one hopper, the set temperature was 255 ° C, and the screw rotation speed was 200.
Under a kneading condition of rpm, the mixture was melt-kneaded to obtain a composition, and then pelletized to obtain a thermoplastic resin composition. Production speed is 2
It was 0 kg / hr. The obtained pellets were dried with hot air at 120 ° C. for 6 hours and then injection molded to obtain various test pieces. Table 1 shows the evaluation results. [Comparative Examples 1 to 5] Kneading was carried out in the same manner as in the examples with the components and the compounding ratios shown in Table 1 to obtain pellets. Further, drying and injection molding were performed in the same manner as in the examples to obtain various test pieces. Table 2 shows the evaluation results.

[0050]

[Table 1]

[0051]

[Table 2]

From the results of the examples in Table 1 and the comparative examples in Table 2,
A molded article made of the thermoplastic resin composition of the present invention has higher tensile elongation at break, tensile / bending strength and Izod impact value, lower specific gravity and lower shrinkage ratio than the comparative example. Further, it can be seen that the melt viscosity is low and the moldability is excellent.

[0053]

The thermoplastic resin composition of the present invention has excellent mechanical properties and moldability and is light in weight, so that it is useful for electric and electronic parts and precision molded parts having strict dimensional accuracy.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryo Saito 5-6-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Center of Mitsubishi Engineering Plastics Co., Ltd. (72) Yoshitaka Kanazawa 5-chome, Higashi-Yawata, Hiratsuka-shi, Kanagawa 6-2 F-term in Mitsubishi Engineering-Plastics Corporation Technical Center (Reference) 4J002 BC03X BN13X BN14X CF07W CG00Y CG01Y EW046 EW066 EW116 FD066 FD130 GM00 GN00 GQ00

Claims (9)

[Claims] (A) Polybutylene terephthalate resin (A)
5 to 10% by weight, (B) rubber-modified polystyrene resin 4 to
50% and (C) aromatic polycarbonate resin 1 to 40
A thermoplastic resin composition containing a resin component consisting of% by weight. 2. The thermoplastic resin composition according to claim 1, wherein (A) the polybutylene terephthalate resin is a polybutylene terephthalate homopolymer. 3. (A) polybutylene terephthalate resin 8
The thermoplastic resin composition according to any one of claims 1 and 2, wherein the content is 0 to 50% by weight. 4. The thermoplastic resin composition according to claim 1, wherein the rubber content in the rubber-modified polystyrene resin (B) is 1 to 40% by weight. 5. The thermoplastic resin composition according to claim 1, wherein the rubber component constituting the rubber-modified polystyrene resin (B) is a conjugated diene type. 6. The thermal method according to claim 1, wherein the content of the rubber and the styrene monomer component in the rubber-modified polystyrene resin (B) is 90% by weight or more. Plastic resin composition. 7. The method according to claim 1, wherein the aromatic polycarbonate resin (C) is a polycarbonate polymer or copolymer prepared by reacting bisphenol A with phosgene or a carbonic acid diester. Item 2. The thermoplastic resin composition according to item 1. 8. The method according to claim 1, wherein the organic phosphorus compound (D) is contained in an amount of 0.01 to 0.5 part by weight based on 100 parts by weight of the total amount of the resin component. 5. The thermoplastic resin composition according to item 1. 9. The method according to claim 1, wherein (E) the organic phosphorus compound is a long-chain dialkyl acid phosphate.
9. The thermoplastic resin composition according to any one of items 1 to 8.