JPH10195304A - Resin composition improved in weld line dielectric strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can give injection moldings improved in weld line dielectric strength without detriment to heat resistance and dimensional stability by mixing a resin composition reinforced with glass fibers and/or talc and/or mica with a specified amount of a polytetrafluoroethylene powder having a specified particle diameter. SOLUTION: A resin composition (e.g. PP) reinforced with 20-60wt.% glass fibers and/or talc and/or mica is mixed with 0.5-10wt.% polytetrafluoroethylene powder having a particle diameter of 2-20μm. The glass fibers with which the PP resin is reinforced are desirably ones having a fiber length of 0.2-3mm, desirably 0.4-2mm (in terms of the length of the remaining fibers in a molding), a diameter of 6-23μ, desirably 9-17μm. The talc is desirably one having a mean particle diameter of 1-20μm, desirably 5-12μm. The mica is desirably one having a mean particle diameter of 5-50μm, desirably 7-30μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art Injection molded products of polypropylene with talc, which have good electrical insulation, are widely used for a distributor cap, a deflection yoke of a television receiver, and components around a high voltage, which are one of automobile parts. . The present invention prevents the electrical degradation of the weld line of these parts,
An object of the present invention is to provide a composition and a molded article having a remarkable effect on improving the weld line dielectric strength.

[0002]

2. Description of the Related Art The parts around a distributor cap and an ignition coil necessary for ignition of an automobile engine include electric insulation, heat resistance, dimensional stability, resin price, etc. because of handling high voltage. In view of this, injection moldings of talc-containing polypropylene are often used. However, in the case of a vehicle type used at a higher voltage or insufficient dielectric strength, a thermosetting resin or an expensive engineering plastic resin may be used. In addition, as the performance of the engine becomes higher, the distributor cap has a complicated shape, and the working voltage tends to be higher. In the case of ordinary polypropylene containing 40% talc, troubles that cause insulation failure often occur. As described above, components such as the deflection yoke and high-voltage parts of a television receiver have good electrical insulation, heat resistance,
Although talc-containing flame-retardant polypropylene having good dimensional stability is often used, the voltage to be handled is increasing as the size increases, for example, as in a television receiver. Higher voltages can cause insulation failure and can cause fires. In many cases, electricity ran on the weld line of the molded product, and the insulation was poor due to carbonization due to electrical deterioration. Therefore, there were many design difficulties, such as not forming a weld line near the live part.

[0003]

As is apparent from the above description, the object of the present invention can be solved only by a method which does not produce a weld of an injection molded product in the prior art. It is an object of the present invention to provide a composition and a molded article whose proof stress can be solved with a small amount of additives without impairing the performance of the current material such as heat resistance, dimensional stability and economy.

[0004]

The present invention has the following constitutions (1) and (2). (1) One or three of glass fiber, talc and mica
A resin composition obtained by mixing 0.5 to 10% by weight of a polytetrafluoroethylene powder having a particle size of 2 to 20μ with a resin composition reinforced with a total amount of 25 to 60% by weight of seeds.

(2) A resin composition in which one to three of glass fiber, talc and mica are reinforced in a total amount of 25 to 60% by weight is added to polytetrafluoroethylene having a particle size of 2 to 20 μm. A molded article obtained by molding a resin composition obtained by mixing 0.5 to 10% by weight of a powder.

The configuration and effect of the present invention will be described in detail below. The glass fiber used in the present invention, a polypropylene resin reinforced with talc or mica is a molded article of glass fiber because of its excellent rigidity, heat deformation temperature, dimensional accuracy, weld line strength, dielectric strength, weld dielectric strength, and the like. Refers to a reinforced polypropylene resin having a residual glass fiber length of 0.2 to 3 mm, preferably 0.4 to 2 mm, and a diameter of the glass fiber of 6 to 23μ, preferably 9 to 17μ, wherein the glass fiber is It may be a long fiber pellet supplied in the form of roving, or a compound pellet cut into 1.5 to 9 mm and kneaded with chopped strands.

The talc-reinforced polypropylene resin refers to a reinforced polypropylene resin obtained by kneading and granulating a talc powder having an average particle diameter of 1 to 20 μm, preferably 5 to 12 μm, and a polypropylene resin.

The mica-reinforced polypropylene resin refers to a reinforced polypropylene resin obtained by kneading and granulating a mica powder having an average particle size of 5 to 50 μm, preferably 7 to 30 μm, and a polypropylene resin.

These reinforcing materials may be used alone or in combination of two to three types. The total amount of one, two or three types of reinforcing materials may be 20 to 65% by weight, preferably Is 25 to 60% by weight. In the case of such a reinforced polypropylene, if the total amount of the reinforcing material is not more than 20% by weight, satisfactory performance in terms of flexural modulus, heat deformation temperature, and dimensional accuracy cannot be obtained. The tensile strength becomes extremely low, and it is difficult to produce a granulated composition.

In the present invention, a polypropylene resin is a propylene-alpha olefin copolymer or a homopolymer such as a crystalline propylene homopolymer, a crystalline propylene-ethylene copolymer, and a crystalline propylene-ethylene-butene copolymer. A resin obtained by grafting a copolymer with an unsaturated organic acid can be exemplified. Examples of the unsaturated organic acid include maleic anhydride, itaconic anhydride, acrylic acid anhydride and the like, and preferably, maleic anhydride is used. Specifically, a small amount of an organic peroxide and 0.1 to 0.5% of the unsaturated organic acid are well mixed at room temperature with the above-mentioned polypropylene powder, and pelletized by a twin-screw extruder. can get.
A small amount of a known heat stabilizer may be mixed during granulation. In the composition of the present invention, the anhydride-grafted polypropylene thus modified may be used in all or a small amount, or the modified anhydride-grafted polypropylene may not be used.

The present invention relates to a composition comprising the reinforced polypropylene resin composition and 0.2 to 10% by weight of a PTFE powder having a particle size of 2 to 20 μm, and molding the composition. Related to molded products, PTF
When the particle size of E is smaller than 2 μm, the effect of improving the weld dielectric strength is low, and when the particle size exceeds 20 μm, the weld line tensile strength is greatly reduced, which is not suitable for practical use. When the addition amount of PTFE is less than 0.5% by weight, the effect of improving the weld dielectric strength is low, and when the addition amount of PTFE exceeds 10% by weight, the weld line tensile strength is greatly reduced, which is not suitable for practical use. The method of mixing PTFE may be directly mixing with the reinforced resin pellets for molding, or may be used in the form of a master batch pellet having a high PTFE concentration, or may be kneaded with an extruder at the time of producing reinforced resin pellets.

[0012]

The present invention will be described below by way of examples. The details of the test methods and materials used in the examples are as follows.

Test Method (1) Weld Dielectric Strength Test: Penetration dielectric strength of a molded product weld was measured by a method based on JIS K-6911. (See FIG. 1) (2) Dielectric strength test: The through dielectric strength of the non-weld part of the molded product was measured by a method based on JIS K-6911. (3) Heat deformation temperature test (HDT): JIS K-720
It measured by the test method according to 7. Load is 1.82M
p. (4) Dimensional accuracy: 150 for non-weld part dielectric strength measurement
The molding shrinkage from the mold dimensions of a flat molded product of × 150 × 2.0 mm was measured. (5) Flexural modulus: Measured by a test method according to JIS K-7203. (6) Weld line strength: Measured by a test method according to JIS K-7113.

Material Details The reinforced polypropylene resin (abbreviated as PP-i) and PTFE used are described below. PP-1 A long fiber reinforced polypropylene resin using a polypropylene homopolymer having a crystal melting point of 165 ° C. and having a resin content of 60% by weight. (Chisso Corp. Funkster LR24A) PP-2 The average fiber length of the glass fibers produced by the melt-kneading method is 0.6 mm, the glass fiber content is 40% by weight,
Short fiber glass reinforced polypropylene resin with a polypropylene resin content of 60% by weight. PP-3 A reinforced polypropylene resin kneaded with 30% by weight of talc having an average particle size of 10 μm. (Example: NissopolyPro Oleform TC) PP-4 A reinforced polypropylene resin kneaded with 40% by weight of talc having an average particle size of 10 μm. (Example: Nittopolypro oleform TA) PP-5 A reinforced polypropylene resin in which PP-3 and 50% by weight of talc are kneaded. PP-6 A reinforced polypropylene resin kneaded with PP-3 and 60% by weight of talc. PP-7 A reinforced polypropylene resin kneaded with 60% of mica powder (325 mesh whole). PP-8 A reinforced polypropylene resin obtained by mixing 50% by weight of talc having an average particle diameter of 10μ, 48% by weight of a polypropylene resin and 2% by weight of PTFE powder having a particle diameter of 5μ, melt-kneaded, and pelletized. PTFE-1 PTFE powder having a particle size of 5 μm. PTFE-2 A mixture of 80% by weight of PTFE powder having a particle size of 5μ and 20% by weight of a polypropylene resin was melt-kneaded and pelletized.
TFE resin masterbatch pellets. PTFE-3 PTFE powder having a particle size of 1 μm. PTFE-4 PTFE powder having a particle size of 30 μm.

Molding JIS K-6911 Resin plate for measuring dielectric strength is 150
It was prepared by molding using a × 150 × 2.0 mm film gate mold with the following injection molding machine. For the resin plate for measuring the weld dielectric strength, the gate of the same mold was used as a film gate at both ends, and a weld line was formed in the center to prepare a test piece. JI
For SK-7203 flexural modulus measurement, weld tensile strength test, and K-7203 heat distortion temperature (HDT) test specimens, use the test specimens obtained by the following injection molding using a combination specimen mold. did.

Molding machine Molding was performed using a Nissei Plastic Industries FE160S25ASE type injection molding machine, and various performance evaluations were performed. The molding was performed at a cylinder temperature of 250 ° C. and a mold temperature of 50 ° C.

Examples 1 to 16 Table 1 shows the results of a weld dielectric strength (KV / mm) test.

[0018]

[Table 1]

Comparative Examples 1 to 18 Table 2 shows the results of Comparative Examples 1 to 18.

[0020]

[Table 2]

Examples 1 to 16 Table 3 shows other test items and judgments for Examples 1 to 16.

[0022]

[Table 3]

Thermal deformation temperature: x below 70 ° C., and を above 70 ° C. Flexural modulus: less than 3000 MPa x 3000 MPa
The above was evaluated as ○. Weld tensile strength: x was less than 10 MPa, and ○ was 10 MPa or more. Molding shrinkage: 1.2% or more was evaluated as x, and less than 1.2% was evaluated as ○. Weld strength: less than 44Kv x, more than 44Kv
And

Comparative Examples 1 to 22 Table 4 shows other test items and judgments for Comparative Examples 1 to 22.

[0025]

[Table 4]

Comparative Example 19 = 5 PTFE-3 added to PP-4
Weight% additive. Comparative Example 20 = PP-4 added with 5% by weight of PTFE-4. Comparative Example 21 = PP-4 added with 0.2% by weight of PTFE-1. Comparative Example 22 = PP-4 added with 15% by weight of PTFE-1.

A method for measuring the dielectric strength of a weld line according to the above-described examples and comparative examples will be described. (1) Method: JIS K-6911 short-time method (1KV
/ Sec pressure rise) 30 ° C in oil (2) Test piece Molding machine: Nissei Plastic Industries FE160S25ASE Screw in-line type injection molding machine Mold: 150 × 150 × 2mm thick double-sided film gate mold (non-weld is single-sided film gate) test The piece was set as shown in FIG. 1 and the weld line insulator strength was measured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for measuring a weld line dielectric strength according to an example of the present invention.

[Explanation of symbols]

 1 Test piece 2 Upper electrode 3 Lower electrode 4 Weld line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 27:18)

Claims (2)

[Claims] 1. A polytetrafluoroethylene powder having a particle size of 2 to 20 μm in a resin composition reinforced with one to three of glass fiber, talc and mica in a total amount of 25 to 60% by weight. A resin composition obtained by mixing 0.5 to 10% by weight of 2. A polytetrafluoroethylene powder having a particle size of 2 to 20 μm in a resin composition reinforced with one to three of glass fiber, talc and mica in a total amount of 25 to 60% by weight. Molded article obtained by molding a resin composition obtained by mixing 0.5 to 10% by weight of