JPS631987B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a fiber-reinforced thermoplastic polyester composition that has excellent antistatic properties and electrical insulation properties, as well as high impact resistance. Thermoplastic polyesters, especially thermoplastic polyester compositions reinforced with fibrous reinforcing materials such as glass fibers, have excellent mechanical properties and heat resistance, and are therefore widely used in various applications. On the other hand, it has high specific volume resistivity and surface resistivity, and has drawbacks such as being easily charged by friction, attracting dust, and easily causing electrostatic damage. The reality is that its use is restricted in fields such as audio equipment parts. Generally, methods for imparting antistatic properties to thermoplastic plastics include (1) a method of adding a so-called antistatic agent whose main component is a surfactant; (2) A method of adding conductive carbon powder or metal powder such as aluminum, and (3) A method of adding a fibrous reinforcing material whose surface is metallized (Japanese Patent Publication No. 19423/1983) have been proposed. However, when these methods are applied to thermoplastic polyester, the antistatic effect of method (1) is insufficient, and the antistatic agent bleeds out onto the surface of the molded product, so the effect is not permanent. Moreover, there are problems such as contamination of the surface of the molded product. In addition, in method (2) above, it is necessary to add a large amount of additives in order to develop sufficient antistatic properties, and although antistatic properties are imparted, electrical insulation properties are lost, resulting in unbalanced electrical properties. Not only does this method not satisfy the above requirements, but when this method is applied to glass fiber reinforced polyester, mechanical properties such as impact resistance are significantly reduced, so a balance between mechanical properties and electrical properties cannot be expected. Furthermore, although the electrical properties are improved to some extent in method (3) above, there is a problem in that the mechanical properties are considerably inferior to that of so-called glass fiber reinforced polyester. Therefore, the present inventors have conducted extensive studies with the aim of obtaining a highly improved thermoplastic polyester that has well-balanced electrical properties such as antistatic properties and electrical insulation properties, and mechanical properties such as impact resistance. As a result, we discovered that by adding both so-called ordinary glass fiber and aluminum-coated glass fiber to thermoplastic polyester, a synergistic improvement effect can be obtained in both electrical properties and mechanical properties. Reached. That is, the present invention is a composition comprising thermoplastic polyester mixed with (A) glass fiber and (B) glass fiber coated with aluminum,
The blending ratio of (A) + (B) is 3 to 70% by weight based on the composition
The present invention provides a fiber-reinforced thermoplastic polyester composition characterized in that the ratio of (B)/(A)+(B) is 5 to 90%. The composition of the present invention has extremely excellent antistatic properties without reducing the good electrical insulation properties of thermoplastic polyester. Specifically, the molded product obtained from the composition of the present invention has a surface resistivity of 10 ⁷ to ^{10 11} Ω, and has the effect of immediately dissipating static electricity generated in the molded product due to friction, impact, etc. This molded product not only has a specific volume resistivity of 10 ¹² Ω or more, but also maintains excellent electrical insulation properties. Surprisingly, (B) this electrical property improvement effect of the present invention is more remarkable than when aluminum-coated glass fiber is used alone;
This can be said to be a synergistic effect due to the combined use of seed glass fibers. The reason for this effect is not clear, but it is probably due to the antistatic effect brought about by regularly arranging glass fibers (B) in the polymer, which have a larger L/D than ordinary powdered antistatic agents. This is thought to be due to the fact that the addition of glass fiber (A) further improves the directionality and regularity of glass fiber (B). Furthermore, the molded article obtained from the composition of the present invention has significantly better impact resistance than a molded article containing only either glass fiber (A) or (B), and has mechanical strength. Synergistic effects are also expected in terms of properties. The synergistic effect of such impact resistance is that of glass fiber (A)
In addition, the reinforcing effect of glass fiber (B) is mainly controlled by fiber length, diameter, and interfacial adhesion force.
This is thought to be due to the fact that the presence of this increases the interfacial adhesion between the thermoplastic polyester and the glass fiber. The thermoplastic polyester used in the present invention is a polymer or copolymer obtained by a condensation reaction containing a dicarboxylic acid (or an ester-forming derivative thereof) as a main component. The dicarboxylic acid components mentioned here include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, bis(p
-carboxyphenyl)methane, anthracene dicarboxylic acid, aromatic dicarboxylic acids such as 4,4'-diphenyl ether dicarboxylic acid, adipic acid,
Aliphatic dicarboxylic acids such as sebacic acid and azelaic acid, 1,3-cyclohexanedicarboxylic acid,
Examples include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, ester-forming derivatives thereof, and mixtures thereof. In addition, the diol component has 2 to 10 carbon atoms.
aliphatic diols i.e. ethylene glycol,
Propylene glycol, 1,4-butanediol, neobentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanediol, etc.
Alternatively, long-chain glycols with a molecular weight of 400 to 6,000, such as polyethylene glycol, polytetramethylene glycol, and mixtures thereof may be mentioned. Specific examples of thermoplastic polyesters include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polybutylene sebacate, and polyethylene-2,6-naphthalate. Particular preference is given to using polyethylene terephthalate and polybutylene terephthalate with. The glass fiber (A) used in the present invention is not particularly limited to those generally used as fibrous reinforcing materials for plastics, but may have an average diameter of 5 to 5.
20μ, especially 10-15μ, average fiber length 0.2mm or more,
In particular, those with a diameter of 0.4 to 6 mm are preferably used. In addition, the glass fiber coated with aluminum (B) used in the present invention is a surface-metalized glass fiber in which aluminum is attached to the surface of the glass fiber by a vacuum deposition method, etc., and the average diameter is 50μ or less and the average fiber length is 50mm. The following are preferably used: The above glass fiber for thermoplastic polyester
The blending amount of (A) and (B) is such that the blending ratio of (A) + (B) is 3 to 70% by weight, especially 10 to 50% by weight based on the total composition,
And the ratio of (B)/(A) + (B) is 5 to 90%, especially 20 to 80
% is selected from the range. If the blending ratio of (A) + (B) is less than 3% by weight, the effect of improving electrical and mechanical properties will be small, and if it is more than 70% by weight, the surface gloss and tensile strength of the molded product will decrease, which is undesirable. . Further, if the ratio of (B)/(A)+(B) is less than 5%, the effect of improving electrical properties is small, and if it is more than 90%, the impact resistance decreases, which is not preferable. The fiber-reinforced thermoplastic polyester composition of the present invention may further contain various types of antistatic agents, and the combined use of these agents can further enhance the antistatic effect. The various antistatic agents mentioned here include nonionic, cationic, and anionic surfactants, such as polyethylene glycol, sodium dodecylbenzesulfonate,
Examples include sodium lauryl sulfate. Further, various lubricants and mold release agents that act as internal and external lubricants can be added to the thermoplastic polyester composition of the present invention, and moldability can be improved by adding these agents. Examples of these lubricants and mold release agents include aliphatic carboxylic acid metal salts, fatty acid esters, montan wax, organic siloxanes, and synthetic waxes (polyalkylene waxes). Furthermore, the fiber-reinforced thermoplastic polyester composition of the present invention includes, for example, nucleating agents such as talc, clay, wollastenite, mica, kaolin, and thyroid, reinforcing materials such as glass beads, asbestos, calcium carbonate, kaolin, mica, and wollastenite. and other common plastic additives such as plasticizers, flame retardants, heat stabilizers, UV absorbers, pigments, dyes, etc. In addition, thermoplastic polyester
It may also be a blend of other plastics, such as polyolefin resins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymers, polyamide resins, polyester resins, polycarbonates, ABS resins, etc. in an amount of 50% by weight or less. The fiber-reinforced thermoplastic polyester composition of the present invention has excellent electrical insulation and antistatic properties, and has good impact resistance, so it is useful for various mechanical parts, electrical equipment parts, and electronic equipment parts, and is particularly useful for static electricity. Electrical and electronic equipment whose performance and lifespan are affected by the generation of electricity, especially gears, rollers, knobs, cams, rotating parts, bearings, plates, cases, etc. used in electroacoustic equipment parts and watches. Suitable for this purpose. The present invention will be explained in further detail by giving examples below. In addition, (A) glass fiber in the examples has an average diameter
13μ and an average fiber length of 3mm, and (B) aluminum-coated glass fiber had an average diameter of 15μ and an average fiber length of 6mm. Furthermore, the surface resistivity and volume specific resistivity in the examples are values measured using a super megohmmeter manufactured by Toa Denpa Kogyo Co., Ltd.
In addition, impact resistance was evaluated by measuring Izod impact force according to ASTMD256. Example 1 Polybutylene terephthalate with a relative viscosity of 1.45 was blended with (B) aluminum-deposited glass fiber (Al-GF) of the above size, (A) glass fiber (GF), and talc in the proportions shown in Table 1. 250
The mixture was melted and kneaded using a 65 mmφ extruder set at ℃ to form chips. Then, injection molding is performed from each of the above chips.
A square plate molded product (M) of 40 x 40 x 3 (thickness) mm and a sheet (S) of 400 mm (width) x 2 mm (thickness) were formed by extrusion molding, and their antistatic and impact resistance properties were evaluated. was evaluated. The results are shown in Table 1. Table 1 also shows the results of a similar evaluation using polyethylene terephthalate (PET) with a relative viscosity of 1.35 instead of polybutylene terephthalate.

[Table] As is clear from Table 1, GF(A) and Al-GF
When (B) is used alone (Nos. 13 to 17), both electrical properties and impact resistance cannot be satisfied in balance, but when both are used together (Nos. 1 to 12), the electrical properties A synergistic improvement effect can be obtained in both aspects of impact resistance and impact resistance.

Claims (1)

[Claims] 1 A composition comprising thermoplastic polyester mixed with (A) glass fiber and (B) glass fiber coated with aluminum, where the blending ratio of (A) + (B) is 3 per composition. ~70% by weight, and (B)/(A)+(B)
A fiber-reinforced thermoplastic polyester composition characterized in that the proportion of is 5 to 90%.