JPH1180518A - Resin composition for optical pickup part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having an improved elastic modulus and extremely high internal loss and useful for a part of an optical pickup by including a liquid crystal polymer, an inorganic fibrous filler and an aramid fiber in a specified proportion. SOLUTION: This composition comprises (A) 100 pts.wt. liquid crystal polymer, (B) 50-400 pts.wt. inorganic fibrous filler and (C) 1-100 pts.wt. aramid fiber. For example, the component A is a polyester called as a thermotropic liquid crystal polymer and obtained by combining an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. The component B is preferably a carbon fiber, an aluminum borate whisker, a potassium titanate whisker or the like. The component C is a chopped fiber comprising a poly-para-phenylene terephthalamide and having 10-15 μm diameter and 0.5-6.0 mm length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for an optical pickup part in an optical disk device such as a video disk player and a digital audio player.

[0002]

2. Description of the Related Art An optical pickup generally includes an optical frame for fixing optical elements such as a light-emitting element, a light-receiving element, and a mirror, an actuator for causing an objective lens and an objective lens holder to follow the movement of an optical disk, and an optical pickup. A base frame that holds the actuator section and forms an optical path with the optical frame. [For example, Japanese Utility Model Laid-Open No. 1-45315]

In particular, since the actuator section is required to have dimensional stability and is always exposed to sound up to 20 kHz, there is a possibility that data on the optical disk may be erroneously read due to higher-order resonance due to sound, that is, chatter. . It is thought that this is due to the internal loss of the material forming the actuator and the lack of specific elastic modulus. As a countermeasure, high-order resonance due to sound can be prevented by forming the actuator integrally with metal die-casting such as aluminum. Was prevented.

In recent years, the weight and cost of optical pickups have been reduced, and attempts have been made to replace metal with synthetic resin. As a conventionally used synthetic resin, a polyphenylene sulfide resin (hereinafter, referred to as PPS resin) is used, and a filler is added to and mixed with the resin to increase the elasticity and obtain a molded product having a high resonance frequency band. . However, when the resonance frequency is further shifted to a higher frequency side with the improvement in the performance of the optical pickup,
Since improvement in internal loss cannot be expected with PPS resin, it was insufficient as a material for high-performance optical pickup parts.

[0005] Examples of the resin filler include long fibers such as carbon fiber and glass fiber, potassium titanate whisker, aluminum borate whisker, calcium carbonate, basic magnesium sulfate, silicon carbide, chrysotile, wollastonite and the like. Inorganic fibers are used, and a high elasticity filler such as carbon fibers, aluminum borate whiskers, silicon nitride, and silicon carbide is blended in a large amount to increase the elasticity of the resin composition. However, when these inorganic fillers are blended in a large amount in the resin, the elastic modulus of the resin composition increases sequentially with the blending amount of the inorganic fillers, and the resonance frequency band can be increased. And the resonance peak increases with the compounding amount of

[0006]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention improves the elastic modulus of a resin composition,
An object of the present invention is to provide a resin composition that can be used as a part of an optical pickup having extremely high internal loss.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive tests and researches to achieve the intended purpose. As a result, 50 parts by weight of the inorganic fibrous filler was added to 100 parts by weight of the liquid crystal polymer.
The present invention has been accomplished by blending ア ラ 400 parts by weight and aramid fiber in a proportion of 1１００100 parts by weight.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Representative liquid crystal polymers (hereinafter referred to as LCP resins) suitable for the practice of the present invention are polyesters called thermotropic liquid crystal polymers. (1) Aromatic dicarboxylic acid and aromatic (2) Combination of different aromatic hydroxycarboxylic acids (3) Combination of aromatic dicarboxylic acid and nucleus-substituted aromatic diol (4) Polyethylene terephthalate Such as those obtained by reacting an aromatic hydroxycarboxylic acid with a polyester, etc., which forms an anisotropic melt at a temperature of 400 ° C. or lower, has a high internal loss, and has extremely excellent melt fluidity. Since a thin molded product of about 0.1 to 0.3 mm can be easily obtained, It is suitable as a material for up parts. Incidentally, ester-forming derivatives thereof may be used in place of these aromatic carboxylic acids, aromatic diols and aromatic hydroxycarboxylic acids.

As the inorganic filler used in the practice of the present invention, any material may be used. However, in order to improve the elastic modulus, carbon fiber, aluminum borate whisker, wollastonite, potassium titanate are used. Whiskers, silicon carbide, silicon nitride, and the like are preferable, and two or more of these may be used in combination.

As the aramid fiber used in the practice of the present invention, any fiber may be used as long as it is obtained by polymerization of an aromatic diamine and an aromatic dicarboxylic acid. For example, polyparaphenylene terephthalate may be used. Lamide, copolyparaphenylene.3.4'oxydiphenylene terephthalamide, polymetaphenylene isophthalamide and the like can be used.

The aramid fiber used in the practice of the present invention is a chopped fiber having a diameter of 10 to 15 μm and a length of 0.5 to 6.0 mm. There is a disadvantage that the properties are deteriorated.

The resin composition of the optical pickup part according to the present invention contains 50 to 400 parts by weight of an inorganic fibrous filler and 1 to 100 parts by weight of an aramid fiber based on 100 parts by weight of an LCP resin. Preferably, the inorganic fibrous filler is 70 to 150 parts by weight, and the aramid fiber is 3 to 25 parts by weight, based on 100 parts by weight of the LCP resin.
It should be adjusted to the range of parts by weight. If the amount of the inorganic filler is less than 50 parts by weight based on 100 parts by weight of the LCP resin, the elastic modulus is lowered and it is difficult to avoid resonance trouble due to sound. In addition to impairing the moldability of the composition, the specific gravity of the resin composition increases, which is not suitable for practical use. In addition, LCP resin 100
If the amount of the aramid fiber used is less than 1 part by weight, the internal loss of the resin composition is reduced, and the object of the present invention cannot be achieved. Decrease the elastic modulus of the object.

The resin composition of the optical pickup part of the present invention may contain an antioxidant, an ultraviolet absorber, a lubricant, a plasticizer and the like within a range not exceeding 2% by weight of the resin composition without deteriorating its performance. Stabilizers can be included.

The kneading of the LCP resin and the inorganic filler can be performed by a known method. For example, the mixture may be uniformly mixed using a mixer such as a ribbon blender, a tumbler mixer, and a Henschel mixer and then melt-kneaded, or may be simultaneously mixed and kneaded using a Banbury mixer, a screw kneader, or the like. A pellet can be formed by kneading, and a molded article can be produced using the pellet by various molding methods, usually an injection molding method.

[0015]

The present invention will be specifically described below based on examples and comparative examples. The inorganic fibers used in the practice of the present invention are not limited to the following examples. In addition,
Raw materials used in Examples and Comparative Examples are as follows. (1) LCP resin (made by Unitika, trade name [Rodrun L
C-5000]) (2) Carbon fiber (Toho Rayon Co., Ltd., trade name [Vesfight HTA-C6-SR]) (3) Aluminum borate whisker (Shikoku Chemical Industry,
(4) Potassium titanate whisker (Otsuka Chemical, trade name [Tismo]) (5) Aramid fiber (Teijin [Technola T-3, trade name)
22EH])

[Examples 1 to 4] LCP resin and aramid fiber are twin-screw extruder [TEM35-B, manufactured by Toshiba Machine Co., Ltd.]
Kneading with aluminum borate, and adding aluminum borate whisker and potassium titanate whisker by side feed.
It was melt extruded at 90 ° C. and pelletized. When carbon fibers were used, the LCP resin, aramid fibers and carbon fibers were kneaded using a twin-screw extruder [TEM35-B, manufactured by Toshiba Machine Co., Ltd.], and aluminum borate whiskers were charged by side feed. A test piece and a pickup component were produced from the thus obtained pellets using an injection molding machine having a mold clamping pressure of 30 tons. The test piece was subjected to a bending test (according to ASTM D-790), and an elastic modulus and an evaluation test were performed. For pickup parts, the pickup actuator is actually
It was incorporated in a D player and the resonance frequency and the resonance peak were measured with a resonance frequency measuring device. These test results
As shown in Table 1.

Comparative Examples 1-4 Carbon fiber, aluminum borate whiskers, and potassium titanate whiskers were used as the LCP resin for extrusion, molding, and evaluation in the same manner as in Examples 1-3, and the results are shown in Table 1. It was as shown.

The blends of the aramid fibers of Examples 1-4 were compared with those of the comparative examples 1-4 without the aramid fiber.
Since the resin composition of the present invention exhibits a good resonance peak value while maintaining the elastic modulus and the resonance frequency, it is possible to obtain a pickup component having a remarkably large internal loss by the resin composition of the present invention.

[0019]

[Table 1]

[Examples 5 to 7] The aramid fibers and the aluminum borate whiskers were used for the LCP resin.
Extrusion, molding, and evaluation were performed in the same manner as in No. 4, and the results were as shown in Table 2.

[Comparative Examples 5 to 7] In Examples 1 to 5, aramid fibers and aluminum borate whiskers were used for the LCP resin.
Extrusion, molding, and evaluation were performed in the same manner as in No. 4, and the results were as shown in Table 2.

Examples 5 to 7 had good resonance characteristics and moldability. On the other hand, Comparative Examples 5 and 7 had low flexural modulus and low resonance frequency. Further, in Comparative Example 6, although the flexural modulus and the resonance characteristics showed good values, the moldability was poor and it was difficult to practically use.

[0023]

[Table 2]

[0024]

According to the resin composition for optical pickup parts of the present invention, it is possible to provide an optical pickup part having remarkably excellent resonance characteristics.

Claims (1)

[Claims] 1. A resin for an optical pickup part, comprising 50 to 400 parts by weight of an inorganic fibrous filler and 1 to 100 parts by weight of an aramid fiber based on 100 parts by weight of a liquid crystal polymer. Composition.