JPH11293096A - Resin composition for optical pickup deive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent high-order resonance, i.e., chatter, by the sound of an optical pickup device and reading of data by electrical wrong operation by improving the dimensional stability of a resin composition to a great extent which is used as the optical pickup device and, at the same time, by imparting electrical insulating properties and weight-saving to the pickup device. SOLUTION: A desired resin composition comprises a polyester resin composed of a liquid crystalline aromatic polyester resin and an amorphous wholly aromatic polyester resin at a weight ratio of 90:10-10:90 and aluminum borate whiskers as the essential components. In this instance, the amount of the aluminum borate whiskers to be compounded in the resin composition is set to 10-70 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition for an optical pickup component mounted on an optical disk device such as a digital video disk player, a CD-ROM 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, see Japanese Utility Model Laid-Open No. 1-45315]

[0003] In particular, the actuator section is required to be lightweight and dimensionally stable, and is always exposed to sound up to 20 kHz. Therefore, data on an optical disk may be erroneously read due to higher-order resonance due to sound, that is, chatter. Maybe. The cause is considered to be the internal loss of the material forming the actuator part and the lack of specific elastic modulus.
As a countermeasure, high-order resonance due to sound was prevented beforehand by integrally molding the actuator section with metal die casting such as aluminum.

In recent years, the weight and cost of optical pickups have been reduced, and attempts have been made to replace metal with synthetic resin. Conventionally used synthetic resins include polyphenylene sulfide resin (hereinafter referred to as PPS resin) and liquid crystalline aromatic polyester resin (hereinafter referred to as LCP resin).
Among them, the PPS resin composition is made to have high elasticity by adding and blending a filler, and a molded product having a high resonance frequency band can be obtained. When the resonance frequency is further shifted to the higher frequency side, improvement of the internal loss cannot be expected with the PPS resin, which is insufficient as a material for high performance optical pickup parts.

On the other hand, LCP resin has a high internal loss,
It is excellent as a material for sophisticated optical pickup parts because it has excellent melt fluidity and can easily obtain a thin molded product with a thickness of about 0.1 to 0.3 mm. The arrangement of the resin molecules at the time of solidification is remarkable, and the dimensions of the molded article are anisotropic, resulting in poor dimensional stability and high specific gravity. Various improvements have been studied for these reasons, but have not been satisfactory.

As fillers for these resins, long fibers such as carbon fibers and glass fibers, and inorganic fibers such as potassium titanate whiskers, calcium carbonate, basic magnesium sulfate, silicon carbide, chrysotile, and wollastonite are used. However, among these, carbon fibers are most suitable for increasing the elasticity of the resin composition, and when using other fillers to increase the rigidity, it is necessary to mix a very large amount of fillers. The specific gravity of the molded article was increased, and the mechanical strength of the molded article was extremely deteriorated.

However, when carbon fibers are used, the electrical conductivity of the resin composition is increased, and an electrical malfunction occurs due to leakage of a small current, so that mechanical insulation is required in the mechanism. The case was not suitable for optical pickup parts.

[0008]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention improves the elastic modulus by using a resin obtained by polymerizing an LCP resin having a high internal loss and an amorphous wholly aromatic polyester resin, An object of the present invention is to provide a resin composition which can be used as a component of an optical pickup having excellent resonance characteristics, electrical insulation properties, and dimensional stability, which cannot be achieved by a conventional resin composition.

[0009]

Means for Solving the Problems In order to achieve the intended object, the present inventors have set the weight ratio of the liquid crystalline aromatic polyester resin to the amorphous wholly aromatic polyester resin to 90:10.
The present invention relates to a resin composition containing 10:90 polyester resin and aluminum borate whiskers as essential components, wherein the mixing ratio of aluminum borate whiskers in the resin composition is 10 to 70% by weight. Was completed.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] The LCP resin used in the practice of the present invention is a polyester called a thermotropic liquid crystal polymer. 1. Composed of a combination of an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid 2. Those composed of heterogeneous aromatic hydroxycarboxylic acids 3. Composed of a combination of an aromatic dicarboxylic acid and a nucleus-substituted aromatic diol Examples thereof include those obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as polyethylene terephthalate, and among these, an anisotropic melt is formed at a temperature of 400 ° C. or less. Note that, instead of these aromatic carboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids, ester-forming derivatives thereof may be used.

The amorphous wholly aromatic polyester resin used in the practice of the present invention is a wholly aromatic polyester resin comprising a dihydric phenol and a dibasic acid and having an amorphous nature at a temperature of 400 ° C. or less. For example, a polyarylate resin comprising bisphenol A and a phthalic acid derivative can be used.

The aluminum borate whisker used in the practice of the present invention has a fiber diameter of 0.05 to 5 μm and a fiber length of 2
9Al2O3 · 2B2O3 or 2A of １００100 μm
It has a composition represented by l2O3 · B2O3,
In order to enhance the compatibility with the resin and the adhesiveness, a resin whose surface is treated with a silane coupling agent or the like may be used.

The LCP used in the practice of the present invention
The polyester resin comprising the resin and the amorphous wholly aromatic polyester resin has a weight ratio of the LCP resin to the amorphous wholly aromatic polyester resin of 90:10 to 10:90, preferably the LCP resin and the amorphous wholly aromatic polyester resin. The weight ratio of the polyester resin should be between 80:20 and 20:80. When the blending ratio of the amorphous wholly aromatic polyester resin in the polyester resin is less than 10% by weight, the dimensions of the molded product tend to be anisotropic, and the specific gravity of the molded product is increased.
On the other hand, if it exceeds 90% by weight, the melt viscosity of the resin becomes extremely large, making it difficult to carry out extrusion and molding, making it difficult to put into practical use.

The resin composition for an optical pickup component according to the present invention comprises aluminum borate whiskers of 10 to 7%.
It should be present in a proportion of 0% by weight, preferably 30-65% by weight. When the amount of the aluminum borate whisker in the resin composition is less than 10% by weight, the elastic modulus is lowered, and it is difficult to avoid the resonance trouble due to sound.
Conversely, if it exceeds 70% by weight, the resin composition becomes heavy and is not suitable for practical use.

The resin composition of the present invention may contain stabilizers such as an antioxidant, an ultraviolet absorber, a lubricant, and a plasticizer as long as the performance is not deteriorated.

The kneading of the resin and the aluminum borate whisker 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. Pellets are formed by kneading, and a molded article can be produced using the pellets by various molding methods, usually injection molding.

[0017]

The present invention will be specifically described below based on examples and comparative examples. The raw materials used in the examples and comparative examples are as follows, but the content of the present invention is not limited to these raw materials. 1. LCP resin (made by Unitika, trade name [Rodrun LC
-5000]) 2. 2. Polyarylate resin (product name: U-Polymer [U-100], manufactured by Unitika) 3. Aluminum borate whisker (manufactured by Shikoku Chemicals, trade name [Albolex YS3A]) Carbon fiber (trade name, manufactured by Toho Rayon Co., Ltd. [Vesfight HTA-C6-SR])

Examples 1 to 3 According to the composition shown in Table 1, a mixture of an LCP resin and a polyarylate resin was kneaded using a twin-screw extruder [TEM35-B, manufactured by Toshiba Machine Co., Ltd.]. The aluminum borate whisker is fed by feed so as to be 40% by weight of the components, and
It was melt extruded at 40 ° C. and pelletized. A test piece and a pickup component were produced from the pellet thus obtained using an injection molding machine having a mold clamping pressure of 30 tons. For the test piece, a bending test (ASTM D-7)
90), volume resistivity (ASTM D-257)
Compliance), molding shrinkage, and specific gravity were measured, and evaluation tests for elastic modulus, electrical insulation, dimensional stability, and weight reduction were performed. With respect to the pickup components, the actuator of the pickup was actually incorporated into a CD player, the resonance frequency and the resonance peak were measured by a resonance frequency measuring device, and further, a comprehensive component performance test was performed in which the actuator was operated in a change in a high-frequency environment.

[Comparative Examples 1-2] According to the composition shown in Table 1, aluminum borate whisker was introduced into LCP resin and polyarylate resin by side feed so as to be 40% by weight of the components and melted at 290-350 ° C. Extruded and pelletized. The obtained pellets were prepared in Examples 1 to 3.
The results were as shown in Table 1 when molded and evaluated in the same manner as described above.

[0020]

[Table 1]

When only LCP resin is used, large anisotropy is produced in the dimensions of the molded article. When only polyarylate resin is used, the melt viscosity is extremely high, and extrusion and molding are extremely difficult. there were.

Examples 4 to 6 According to the composition shown in Table 2, a mixture obtained by mixing an LCP resin and a polyarylate resin at a weight ratio of 80:20 was twin-screw extruder [TEM35, manufactured by Toshiba Machine Co., Ltd. -B], and aluminum borate whiskers are charged by side feed.
It melt-extruded at 00-340 degreeC, and pelletized. A test piece and a pickup component were produced from the pellet thus obtained using an injection molding machine having a mold clamping pressure of 30 tons. For the test piece, the volume resistivity was additionally measured to the test items of Examples 1 to 3, and the electrical insulation was also investigated. Further, for the pickup component, a long-term reliability test was additionally measured in addition to the test items of Examples 1 to 3, and the results are as shown in Table 2.

Comparative Example 3 According to the composition shown in Table 2,
A mixture obtained by mixing the LCP resin and the polyarylate resin at a weight ratio of 80:20 and carbon fibers are kneaded using a twin-screw extruder [TEM35-B, manufactured by Toshiba Machine Co., Ltd.]
It melt-extruded at 00-340 degreeC, and pelletized. A test piece and a pickup component were produced from the pellet thus obtained using an injection molding machine having a mold clamping pressure of 30 tons. Example 4 for both test pieces and pickup parts
When the evaluation was performed in the same manner as in Examples 6 to 6, the results were as shown in Table 2.
Was as shown in FIG.

Comparative Example 4 According to the composition shown in Table 2,
A mixture obtained by mixing the LCP resin and the polyarylate resin at a weight ratio of 80:20 is twin-screw extruder [Toshiba Machine Co., Ltd.
TEM35-B], and potassium titanate whiskers are charged by side feed, and 300 to 3
It was melt extruded at 40 ° C. and pelletized. A test piece and a pickup component were produced from the pellet thus obtained using an injection molding machine having a mold clamping pressure of 30 tons. The test pieces and the pickup parts were evaluated in the same manner as in Examples 4 to 6, and the results were as shown in Table 2.

[0025]

[Table 2]

The compound containing the carbon fiber of Comparative Example 3 shows good values of the resonance frequency and the resonance peak, but has a small volume specific resistance value and shows conductivity, so that it can be used in a long-term reliability test. Malfunction as a pick-up component frequently occurred. In addition, the compound containing the potassium titanate whisker of Comparative Example 4 had a low elastic modulus, and showed the worst results in the resonance frequency value and the resonance peak value.

[0027]

According to the resin composition of the present invention, it is possible to provide a highly reliable lightweight optical pickup part which is excellent in dimensional stability, electrical insulation and resonance characteristics of a molded article.

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Claims (1)

[Claims] The weight ratio of the liquid crystalline aromatic polyester resin to the amorphous wholly aromatic polyester resin is from 90:10 to 1: 1.
A resin composition containing a polyester resin having a ratio of 0:90 and aluminum borate whiskers as essential components, wherein the blending ratio of aluminum borate whiskers in the resin composition is 10 to 70% by weight. Resin composition for optical pickup parts.