JP2000256538A - Thermoplastic polyester resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic polyester resin composition which has small mold release resistance and can be molded in a molding process in high productivity. SOLUTION: This thermoplastic polyester resin composition comprises (A) 100 pts.wt. of a thermoplastic polyester resin, (B) 0.1-30 pts.wt. of a polyalkylene terephthalate which has a >=6C hydrocarbon group at least at one molecular end, a reduced specific viscosity of <=0.35 dl/g, and a hydroxyl group value of >5 KOH mg/g, and (C) 0-150 pts.wt. of a reinforcing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic polyester resin composition having excellent mold release properties and high productivity in a molding step.

[0002]

2. Description of the Related Art Conventionally, polybutylene terephthalate resin (hereinafter referred to as PBT) and polyethylene terephthalate resin (hereinafter referred to as PET) have been known for their excellent mechanical properties, heat resistance, electrical properties, and chemical resistance. Widely used for electric / electronic parts and automobile parts.
Release properties are required in terms of productivity and prevention of deformation during release of the product. Therefore, in order to improve the release property of the molding material,
Polyethylene wax, esters of higher fatty acids and metal salts of higher fatty acids have been used. However, thermoplastic polyesters and these release agents are poorly compatible,
There is a limit in the amount of the molded product to be added in terms of appearance, and there is a limit to improvement in altitude.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to a thermoplastic polyester resin composition which retains high physical properties and appearance of a thermoplastic polyester, has good releasability, has little deformation upon releasing, and is capable of high cycle. It is an object to provide a product.

[0004]

Means for Solving the Problems The present inventors have intensively studied, studied and studied to solve the above-mentioned problems, and as a result, have finally completed the present invention. That is, the present invention provides a thermoplastic polyester resin (A) having 100 parts by weight, a hydrocarbon group having 6 or more carbon atoms at at least one terminal, a reduced specific viscosity of 0.35 dl / g or less, and a hydroxyl value of 5 KOHmg / g. Polyalkylene terephthalate (B) having a value exceeding 0.1
A thermoplastic polyester resin containing 30 parts by weight and 0 to 150 parts by weight of an inorganic reinforcing material (C).

The thermoplastic polyester resins used in the present invention include polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate,
It is used in one kind or a combination of one or more kinds selected from polyethylene naphthalate, polybutylene naphthalate and / or a copolymer thereof. In particular, in the present invention, polybutylene terephthalate and polyethylene terephthalate are preferred. Glycol components that can be copolymerized with the thermoplastic polyester resin include ethylene glycol, propylene glycol, butanediol, hexamethylene glycol, neopentyl glycol, cyclohexane dimethanol, diethylene glycol, polyethylene glycol, polytetramethylene glycol, polylactone, and the like. Can be As the acid component, for example, naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, adipic acid, sebacic acid and the like can be used as a copolymer component. If the amount of the copolymer component exceeds 20 mol%, heat resistance and crystallinity are undesirably reduced. Also, the weight ratio of phenol to tetrachloroethane is 6: 4.
A thermoplastic polyester having a reduced specific viscosity of 0.4 g / dl at 30 ° C. and having a reduced specific viscosity of 0.4 or more, preferably 0.5 or more is used. If the reduced specific viscosity is less than 0.4, the impact resistance is lowered, which is not preferable.

Further, in the present invention, at least one terminal has a hydrocarbon group having 6 or more carbon atoms, and the reduced specific viscosity is:
A polyalkylene terephthalate having a value of 0.35 dl / g or less and a hydroxyl value exceeding 5 KOHmg / g is used in an amount of 0.1 to 30 parts by weight, preferably 0.2 to 15 parts by weight, based on 100 parts by weight of the thermoplastic polyester resin. Particularly preferably, it is added in an amount of 0.5 to 10 parts by weight. If the amount is less than 0.1 part by weight, the effect is small, and if it exceeds 30 parts by weight, the mechanical properties deteriorate, which is not preferable. On the other hand, when the hydroxyl value is below this value, the adhesion to the polyester resin is reduced, and the properties of the molded product surface are undesirably reduced.
The reason why the specific polyalkylene terephthalate exhibits a high mold release effect is not clear, but when blended in a thermoplastic polyester resin, it is easy to segregate at the interface between the mold and the molded article due to the difference in viscosity, and further the skeleton portion is It is considered that the terminal portion is oriented to the mold surface toward the thermoplastic polyester resin.

As the polyalkylene terephthalate, specifically, polybutylene terephthalate and polypropylene terephthalate are preferable, and at least one terminal must be a hydrocarbon group having 6 or more carbon atoms. This is carried out by esterification using a monofunctional higher fatty acid or higher alcohol, or by addition reaction of glycidyl ether having 6 or more carbon atoms, monooxazoline or monoisocyanate to a carbosyl group or a hydroxyl group. Specifically, it is esterified with 2-ethylhexyl alcohol, lauryl alcohol, stearyl alcohol, lauric acid, stearic acid, montanic acid, etc., or lauryl glycidyl ether, steryl glycidyl ether, 2-ethylhexyl oxazoline, lauryl oxazoline, lauryl isocyanate, phenyl isocyanate. Can be obtained by an addition reaction. The terminal ratio of the hydrocarbon group having 6 or more carbon atoms is required to be 50 mol% or more, and is preferably 75 mol% or more. The hydrocarbon group has 6 or more carbon atoms, preferably 8 or more carbon atoms. If the number of carbon atoms is less than 6, the effect of improving the releasability is reduced, which is not preferable. The molecular weight of the polyalkylene terephthalate used in the present invention is 0.35 or less in terms of reduced specific viscosity. If this value is exceeded, the effect of improving the releasability is reduced. The reason for this is that, due to the difference in viscosity and the size of the hydrocarbon group, the fraction on the surface of the molded article increases, and the release effect due to the hydrocarbon group is reduced. It seems to increase.

In the present invention, 150 parts by weight or less of an inorganic reinforcing material is blended with 100 parts by weight of the thermoplastic polyester resin depending on the use. If it exceeds 150 parts by weight, the fluidity and the appearance of the molded product are undesirably reduced. Examples of inorganic reinforcing materials include fibrous reinforcing materials such as glass fiber, carbon fiber, and aramid fiber, needle-like crystals such as potassium titanate and aluminum borate, glass beads, silica, talc, mica, calcium carbonate, and wollastonite. , Kaolin, clay, magnesium oxide, alumina oxide and the like. Of these, glass fiber / talc, wollastonite, calcium carbonate and combinations thereof are preferred.
As these reinforcing materials, an epoxy silane coupling agent, an amino silane coupling agent, a titanate coupling agent, or the like may be used to improve the adhesiveness to the polyethylene terephthalate resin, that is, to improve the strength and impact strength.

Furthermore, the polyester resin composition of the present invention can be used in combination with a general release agent, for example, a metal salt or ester of a higher fatty acid. Further, other conventional additives such as a heat stabilizer, a weathering agent, a hydrolysis-resistant agent and a pigment may be added. Examples of the heat stabilizer include hindered phenols, thioethers, phosphites, and combinations thereof. Examples of the weathering agent include carbon black, benzophenone, triazole, and hindered amine. Examples of the hydrolysis-resistant agent include carbodiimide, bisoxazoline, epoxy, and isocyanate compounds. As the pigment, a conventional heat-resistant pigment for polyethylene terephthalate can be used.

The resin composition of the present invention is produced by kneading the above-mentioned components using a single-screw extruder, a twin-screw extruder or a kneader. There is no particular limitation on the type of kneader used and the kneading conditions. The molding method is not particularly limited, but injection molding is generally used.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A molded article obtained by using the composition of the present invention obtained by the above-mentioned method is colored by original coating or painting in which a pigment is mixed with a molding material, or is bolted or ultrasonically welded. It is secondary processed by a method such as welding or vibration welding and used as various molded products. Specifically, it can be used for electric and electronic parts such as coil bobbins, switches, relay bases, connectors, and the like, and automotive parts such as air flow meters, air pumps, bobbins, coil cases, and sensor housings.

[0012]

The present invention will be specifically described below with reference to examples. The evaluation of physical properties in the present invention was measured by the following methods. 1) Releasability: Using a mold of a cylindrical molded product having an outer diameter of 40 mm, an inner diameter of 34 mm, and a height of 50 mm and a taper of 2 mm, equipped with a detection sensor for protrusion resistance and mold temperature, and releasing resistance during injection molding. Was measured. 2) Molding cycle time: 100 × 100 with a thickness of 2 mm
The shortest cycle time at which a box-shaped molded product of 30 mm in size could be released from the mold with four 5φ protruding pins was measured. 3) Appearance of molded product: A flat plate of 70 × 150 mm was injection molded, the degree of surface unevenness was observed, and the following three grades were evaluated. ：: uniform, Δ: non-uniform part 5% or less, ×: non-uniform part 5
%that's all

Examples 1 to 10 and Comparative Examples 1 to 7 Combinations are selected from thermoplastic polyester resins, hydrocarbon-terminated polyalkylene terephthalates, and inorganic reinforcing materials shown in Table 1, and a predetermined amount thereof is measured and then reserve. Mixed. Each of the premixes was adjusted to a cylinder temperature of 265-270-270 ° C. from the hopper side at 35Φ.
Into a hopper of the same-direction twin-screw extruder, and melt-kneaded at a screw rotation speed of 100 rpm to obtain pellets. Each of the pellets was preliminarily dried at 130 ° C. for 3 hours, and an injection molding machine having a cylinder temperature set at 260-275-275 ° C. and a mold having a surface temperature of 100 ° C. were selected as molding conditions.
Test pieces were molded and evaluated. The results are shown in Tables 1 and 2.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

As is clear from Tables 1 and 2, the thermoplastic polyester resin composition of the present invention has a release resistance of 15 kg.
It can be seen that the molding cycle time was 42 seconds or less and the appearance of the molded product was excellent. Therefore, since the thermoplastic polyester resin composition of the present invention has a low mold release resistance and a short molding cycle time, the productivity is high, the processing cost can be reduced, and it greatly contributes to the industry.

Continued on the front page F-term (reference) 4J002 CF051 CF052 CF061 CF071 CF072 CF081 CF163 CF272 DA016 DE076 DE146 DE186 DE236 DJ006 DJ016 DJ036 DJ046 DJ056 DK006 DL006 FA043 FA046 FA086

Claims (1)

[Claims] 1. A thermoplastic polyester resin (A) having 100 parts by weight, a hydrocarbon group having 6 or more carbon atoms at at least one terminal, a reduced specific viscosity of 0.35 dl / g or less, and a hydroxyl value of 5 KOHmg / g. 0.1 to 30 parts by weight of polyalkylene terephthalate (B) having a value exceeding the above, inorganic reinforcing material (C) 0
A thermoplastic polyester resin composition, characterized in that the composition contains about 150 parts by weight.