JPH05279560A - Polyester elastomer resin composition for shell member - Google Patents

Abstract

PURPOSE:To provide a polyester elastomer resin composition which can be molded into an article having low molding shrinkage, high dimensional stability at high temperature, and good impact resistance by mixing a thermoplastic polyester elastomer and a liquid-crystal polyester having a specified melting point at a specified ratio. CONSTITUTION:This composition comprises a mixture of a thermoplastic polyester elastomer and a liquid-crystal polyester having a melting point of 180-250 deg.C at a weight ratio of (50.5:49.5) to (99.5:0.5). As the liquid-crystal polyester, one synthesized from p-hydroxybenzoic acid blocks and polyethylene terephthalate is desirable in particular.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition suitable for an outer shell member such as a case material and a cover material for products and parts used in various industrial fields such as mechanical devices, electric products and passenger cars. ..

[0002]

2. Description of the Related Art Thermoplastic polyester elastomers are widely used in various industrial materials, especially automobile parts, in view of their high melting point, high heat aging resistance, oil resistance, chemical resistance and impact resistance as compared with other elastomers. In recent years, blending of polymer blends and inorganic fillers has been frequently performed to further improve such performance. For example, a method of incorporating glass fiber or talc in order to improve the dimensional stability of the product at high temperature. It is known that blending an inorganic filler improves performances such as molding shrinkage, linear expansion and heat sag. .. By blending the thermoplastic polyester elastomer with an inorganic filler, the dimensional stability at high temperature is improved, but the hardness is remarkably increased and the impact resistance is also deteriorated. Further, the method of blending an amorphous polymer such as polyphenylene oxide has a drawback that compatibility is poor and impact resistance is significantly lowered.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a polyester elastomer resin composition having a small molding shrinkage, a high dimensional stability at high temperature, and a molding capable of forming an impact resistant article. Is to

[0004]

The present invention comprises (a) a thermoplastic polyester elastomer and (b) a melting point of 180.
(A) / (b) = 5 with a liquid crystalline polymer at 250 ° C.
It is a polyester elastomer resin composition for outer shell members, which is blended at 0.5 / 49.5 to 99.5 / 0.5 (weight ratio).

The thermoplastic polyester elastomer in the present invention is a block copolymer composed of a high melting point polyester segment and a low melting point polymer segment having a molecular weight of 400 to 6000. The high melting point polyester segment constitutes only the high polymer. The melting point when formed is 15
A thermoplastic polyester elastomer composed of components having a melting point or softening point of 0 ° C. or higher and a melting point or softening point of 80 ° C. or lower when measured only with the low melting point polymer segment components, and the melting point of the thermoplastic polyester elastomer is It is 80 ° C or higher.

The polyester constituting the high melting point polyester segment is terephthalic acid, isophthalic acid, 1,5-
Naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, bibenzoic acid,
Residues of aromatic dicarboxylic acids such as bis (p-carboxyphenyl) methane and 4,4-sulfonyldibenzoic acid and ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, 2,2-
Diester residues such as dimethyltrimethylene glycol, hexamethylene glycol, decamethylene glycol, p-xylene glycol, cyclohexane dimethanol, and the like, or a polyester having two or more kinds of these dicarboxylic acids or two or more kinds of these. Copolyester using diol, or p- (β-hydroxyethoxy)
Benzoic acid, polyesters derived from oxyacids such as p-oxybenzoic acid and residues thereof, polylactones such as polypivalolactone, and 1,4-bis (4,4′-dicarboxydiphenoxy) ethane Among the polyetheresters consisting of the residue of an aromatic ether dicarboxylic acid and the above-mentioned diol residue, and the copolyesters in which the above-mentioned dicarboxylic acids, oxyacids, diols, etc. are combined, those having a melting point of 150 ° C. or higher are used. I can give you. Polybutylene terephthalate is particularly preferable.

The low melting point polymer segment constituent having a molecular weight of 400 to 6000 shows a substantially amorphous state in the polyester block copolymer, and when measured only by the segment constituent, the melting point or It has a softening point of 80 ° C or lower. Its molecular weight is 400-6
000 is suitable. Further, the proportion of the low melting point polymer segment constituent component in the thermoplastic polyester elastomer is 3 to 90%.

As typical low melting point polymer segment constituents, polyether glycols such as polyoxyethylene glycol, polyoxypolypropylene glycol, polyoxytetramethylene glycol and the like and mixtures thereof, and further ether constituents thereof are copolymerized. The copolymerized polyether glycol and the like are shown. Furthermore, carbon number 2 to 1
2 aliphatic or alicyclic dicarboxylic acids and 2 to 10 carbon atoms
Polyesters of aliphatic or alicyclic glycols such as polyethylene adipate, polytetramethylene adipate, polyethylene sebacate, polyneopentyl sebacate, polytetramethylene dodecaneate, polytetramethylene azelate, polyhexahexene Examples thereof include aliphatic polyesters such as methylene azelate and poly-ε-caprolactone, and aliphatic copolyesters prepared by using two kinds of aliphatic dicarboxylic acids or two kinds of glycols. Further, as the low melting point polymer segment constituent component, a polyester polyether block copolymer obtained by combining the above-mentioned aliphatic polyester and aliphatic polyether can be mentioned.

These thermoplastic polyester elastomers can be produced by a usual polymerization method.
A preferred method is to heat the aromatic dicarboxylic acid or its dimethyl ester and the low-melting segment-forming diol to about 150 to 260 ° C. in the presence of a catalyst to carry out an esterification reaction or a transesterification reaction, and then under a vacuum. A method for obtaining a thermoplastic polyester elastomer by carrying out a polycondensation reaction while removing excess low-molecular diol,
A pre-prepared high-melting point polyester segment-forming prepolymer and a low-melting point polymer segment-forming prepolymer are reacted with the ends of their prepolymers. 2
After mixing a functional chain extender and reacting it, a method of obtaining a thermoplastic polyester elastomer by keeping the system in a high vacuum and removing volatile components, a high-melting point high-melting point polyester and a lactone are heated and mixed. Then, there is a method of obtaining a thermoplastic polyester elastomer by carrying out a transesterification reaction while ring-opening polymerization of a lactone.

In the present invention, the liquid crystalline polymer having a melting point of 180 to 250 ° C. means parahydroxybenzoic acid (hereinafter referred to as P
HBA) and a block copolymer of 4,4'-biphenol and terephthalic acid, also P
There are copolymers of blocks of HBA and 2,6-hydroxynaphthoic acid, blocks of PHBA and blocks of 2,6-naphthalenedicarboxylic acid and terephthalic acid, and particularly preferred are blocks of PHBA and polyethylene terephthalate ( Hereinafter, a liquid crystal polymer synthesized from PET). When the melting point exceeds 250 ° C. due to the ratio of components to be combined with the PHBA block and the block property, the thermoplastic polyester elastomer side is easily deteriorated by heat when melt-mixed with the thermoplastic polyester elastomer, which is not preferable.

The outer shell member molded by using the resin composition of the present invention has excellent impact resistance even at a low temperature below freezing, but has a stable shape even at a high temperature around 100 ° C. Shows excellent heat resistance. Further, the resin composition of the present invention has excellent compatibility, and can significantly reduce the molding shrinkage rate as compared with the thermoplastic polyester elastomer, and can improve the dimensional accuracy of the molded product.
Furthermore, since the coefficient of linear expansion can be reduced, the problem of dimensional change due to temperature change is small.

Although the composition of the present invention has many of the above-mentioned desirable properties, it is extremely easy to significantly stabilize the above properties by further incorporating a stabilizer against ultraviolet rays, a stabilizer against thermal oxidation, and a stabilizer against hydrolysis. Can be made. Representatives useful as stabilizers are substituted benzophenones or substituted benzotriazoles as stabilizers against UV light and phenol derivatives as stabilizers against thermal oxidation, such as tetrakis [methylene-3 (3,5- Ditertiarybutyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3.5-ditertiarybutyl-4-hydroxybenzyl) benzene, 4,4 '-
Butylidene bis (6-tertiary butyl metacresol), 4,4′-thiobis (3-methyl-6-tertiary butylphenol), and the like, and aromatic amines such as N, N′-bis (β-naphthyl). ) Paraphenylenediamine, N, N'-bis (1-methylheptyl) -paraphenylenediamine and the like, and thiopropionic acid esters such as dilauryldithiopropionate and distearyldipropionate. Also, combinations of these are effective. The stabilizers against hydrolysis include carbodiimides and mono or polyepoxy.

These blending in the present invention can be carried out at the time of melt kneading or separately. The melt-kneading condition is a single-screw or twin-screw extruder, generally 180
It is common to knead in a temperature range of to 270 ° C., discharge in strands, cool with water, and then chip. If necessary, an underwater cutter, a hot cutter or a mist cutter may be used.

[0014]

EXAMPLES The present invention will be described below with reference to examples. In the examples, simply parts or% means parts by weight or% by weight.
Indicates.

Production Examples 1 to 3 Using dimethyl terephthalate, 1,4-butanediol and polyoxytetramethylene glycol (PTMG) having a number average molecular weight of about 1000, the units of PTMG occupy 25% and 50%, respectively. Polyester / polyether block copolymers (Polymers A and B) were prepared. The solution viscosity ηsp / c was 1.45 for polymer A and 1.71 for polymer B. Polybutylene terephthalate (Toughpet PBT N1000 manufactured by Toyobo) 10
0 parts by weight and 50 parts by weight of ε-caprolactone at 250 ° C.
By heat-mixing at 60 ° C., and performing a transesterification reaction while ring-opening polymerization of the lactone in the reaction vessel for 60 minutes to give a polyester / polyester block copolymer (Polymer C)
Manufactured. The solution viscosity was 1.20.

Examples 1 to 4 and Comparative Examples 1 to 3 Polymers A, B and C obtained in Production Examples 1 to 3 were each dry blended with a liquid crystal polymer (Novaculate E310, E322, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.). Then, the mixture was melt-kneaded with a 40 mmφ single-screw extruder set to a cylinder temperature of 220 ° C. to obtain compositions D to G.

PBT was added to the polymer A obtained in Production Example 1.
(Toughpet PBT, N1000) Polycarbonate (Yupiron S-2000, manufactured by Mitsubishi Gas Chemical Co., Inc.) and talc (Micron White 5000A, manufactured by Hayashi Kasei Co., Ltd.) were dry blended and melt-kneaded under the same conditions as in Examples 1 to 4. went.

[0018]

[Table 1]

Chips of the compositions obtained in Examples and Comparative Examples in Table 1 were dried in a tray dryer at 100 ° C. for 2 hours, and then the test pieces for test and 1 were prepared by an injection molding machine.
A flat plate of 50 × 70 × 3 mmt (mold temperature 40 ° C.) was prepared. Bending test is JIS K7055, impact resistance is JIS
K7110, linear expansion coefficient was in accordance with ASTM D696. The mold shrinkage was measured from the average value of the dimensions of the flat plate in each direction. Heat sag overhangs a 3mm flat plate 10
The amount of droop was measured after 2 hours at 120 ° C. with 0 mm. Furthermore, regarding an injection-molded case with a bottom surface of 50 × 50 mm and a height of 10 mm (thickness 2 mm), 500 g of an iron ball (about 50φ) was dropped from a height of 300 mm with the bottom surface of the case facing upwards to cause cracking. Existence was checked.

The compatibility was judged by the state of the strands discharged from the kneading extruder and the appearance of the molded product when the chips of the above composition were obtained. Good compatibility makes it possible to stably receive a strand of a certain thickness, while poor compatibility makes strands unstable and breaks, or fluctuations in thickness. Was remarkable. In addition, among the molded products, good ones had a beautiful appearance, and defective ones had a flow pattern and graininess.

[0021]

[Table 2]

[0022]

According to the present invention, an outer shell member having both impact resistance at low temperature and shape stability at high temperature can be provided. Further, with the resin composition of the present invention, a molded article having excellent dimensional accuracy and dimensional stability can be obtained.

Claims (1)

[Claims] 1. A thermoplastic polyester elastomer (a) and a liquid crystalline polyester (b) having a melting point of 180 to 250 ° C. (a) / (b) = 50.5 / 49.5-9
A polyester elastomer resin composition for an outer shell member, which is blended at 9.5 / 0.5 (weight ratio).