JP2000273320A - Liquid crystal polymer composition for optical pickup and optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal polymer composition reduced in the tendency to form burrs when molded and improved in the environmental stability of a laser focal point, dimensional accuracy, and vibration-damping properties by including a liquid crystal polymer with a particulate filler and a fibrous filler in a specified ratio. SOLUTION: This composition comprises 100 pts.wt. liquid crystal polymer having a relative viscosity of at least 2.0 dl/g, desirably, 2.0-10.0 dl/g as measured in a 0.1 wt.% solution in pentafluorophenol at 60 deg.C, 5-100 pts.wt., desirably, 10-80 pts.wt. at least one particulate filler selected from among talc, titanium oxide, glass beads, and silica and having a mean particle diameter of 0.1-50 μm and an average aspect ratio of 1-2, and 5-100 pts.wt., desirably, 10-80 pts.wt. at least one fibrous filler selected from a milled fiber and wollastonite and having an average fiber diameter of 0.5-20 μm and an average aspect ratio of at most 10. The total content of the fillers is at most 150 pts.wt., desirably, at most 110 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystalline polymer containing a particulate filler and a fibrous filler, and more particularly to a compact disk, a laser disk, and the like formed from such a liquid crystalline polymer composition. The present invention relates to an optical pickup having excellent environmental stability of a laser focus used for a video disk, a magneto-optical disk and the like.

[0002]

2. Description of the Related Art
The thermoplastic resin used for the optical pickup is required to have a special property of environmental stability of the laser focus (the laser focus is stable even when the environmental temperature changes).
Generally, a polyarylene sulfide resin is used. However, the polyarylene sulfide resin composition is excellent in environmental stability and dimensional accuracy of the laser focus as described above, but is inferior in vibration damping properties, and has problems such as mold corrosion during molding and burrs of molded products. However, it is not sufficiently satisfactory as a resin composition for an optical pickup. On the other hand, liquid crystalline polymers that can form an anisotropic molten phase are known as materials that have excellent dimensional accuracy and vibration damping properties and have extremely few burrs during molding among thermoplastic resins. It is used for Therefore, it is conceivable to use a liquid crystalline polymer as a resin for an optical pickup. However, the liquid crystalline polymer has a drawback that environmental stability at a laser focus is inferior, and its application to an optical pickup has been refrained.

[0003]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive searches and studies on the provision of environmental stability of a laser focus on a liquid crystalline polymer. The present inventors have found that by containing a specific amount of a filler and a specific fibrous filler, respectively, it is possible to improve the environmental stability of a laser focus without greatly reducing mechanical properties, and have completed the present invention. That is, in the present invention, 5 to 10 parts by weight of a particulate filler (B) having an average particle size of 0.1 to 50 μm is added to 100 parts by weight of the liquid crystalline polymer (A).
0 parts by weight and a fibrous filler (C) having an average fiber diameter of 0.5 to 20 μm and an average aspect ratio of 10 or less are 5 to 10 parts by weight.
An object of the present invention is to provide a liquid crystalline polymer composition for an optical pickup, which contains 0 parts by weight and has a total filler content of 150 parts by weight or less.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The liquid crystalline polymer (A) used in the present invention refers to a melt-processable polymer having a property capable of forming an optically anisotropic molten phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope and observing the molten sample placed on the Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere. When the liquid crystalline polymer applicable to the present invention is inspected between orthogonal polarizers, polarized light is normally transmitted even when it is in a molten stationary state, and exhibits optical anisotropy. The liquid crystal polymer (A) as described above is not particularly limited, but is preferably an aromatic polyester or an aromatic polyesteramide, and a polyester partially containing an aromatic polyester or an aromatic polyesteramide in the same molecular chain. Are also in that range. These are preferably at least about 2.0 dl / g, more preferably 2.0 to 10.0 dl / g logarithmic viscosity (I.P.) when dissolved in pentafluorophenol at 60 ° C. at a concentration of 0.1% by weight.
V. ) Is used. The aromatic polyester or aromatic polyesteramide as the liquid crystalline polymer (A) applicable to the present invention is particularly preferably at least one selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxyamines, and aromatic diamines. Aromatic polyesters and aromatic polyester amides having the above-mentioned compound as a component. More specifically, (1) a polyester mainly consisting of one or more aromatic hydroxycarboxylic acids and derivatives thereof; (2) one or two types of mainly (a) aromatic hydroxycarboxylic acids and derivatives thereof And (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof, and (c) at least one of aromatic diols, alicyclic diols, aliphatic diols and derivatives thereof Or (3) mainly one or more of (a) aromatic hydroxycarboxylic acids and derivatives thereof and (b) one of aromatic hydroxyamines, aromatic diamines and derivatives thereof. Polyester comprising a species or two or more species and (c) one or more species of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof (4) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof, and (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof, c) one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof,
(D) at least one or more aromatic diols, alicyclic diols, aliphatic diols and derivatives thereof,
And polyester amides consisting of Further, a molecular weight modifier may be used in combination with the above-mentioned components as needed.

Preferred examples of specific compounds constituting the liquid crystalline polymer (A) applicable to the present invention include:
aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene,
4,4′-dihydroxybiphenyl, hydroquinone,
Resorcinol, the following general formula (I) and the following general formula (II)
Aromatic diols such as compounds represented by the following; terephthalic acid,
Isophthalic acid, 4,4′-diphenyldicarboxylic acid,
2,6-naphthalenedicarboxylic acid and the following general formula (II
Aromatic dicarboxylic acids such as the compounds represented by I); and aromatic amines such as p-aminophenol and p-phenylenediamine.

[0006]

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Particularly preferred liquid crystalline polymers (A) to which the present invention is applied include p-hydroxybenzoic acid and 6-hydroxybenzoic acid.
Hydroxy-2-naphthoic acid, terephthalic acid and p-
Aromatic polyesteramide containing aminophenol as a main constituent unit.

[0008] In order to achieve the environmental stability of the laser focus, which is the object of the present invention, the liquid crystalline polymer (A) 100
5 to 100 parts by weight of a particulate filler (B) having an average particle diameter of 0.1 to 50 μm, and an average fiber diameter of 0.5 to
It is necessary to contain 5 to 100 parts by weight of a fibrous filler (C) having a thickness of 20 μm and an average aspect ratio of 10 or less. In the present invention, as the granular filler (B), fibrous, plate-like,
It refers to a granular material having no spread in a specific direction such as a strip shape, and refers to a material having an average aspect ratio of 1 to 2. Its average particle size is between 0.1 and 50 μm. Specific examples of the particulate filler include kaolin, clay, vermiculite, talc, calcium silicate, aluminum silicate, feldspar powder, acid clay, lauric clay, sericite,
Sillimanite, bentonite, glass powder, glass beads, slate powder, silicates such as silane, calcium carbonate,
Carbonates such as chalk, barium carbonate, magnesium carbonate, dolomite, barite powder, precipitated calcium sulfate, plaster of Paris, sulfates such as barium sulfate, hydroxides such as hydrated alumina, alumina, antimony oxide, magnesia, titanium oxide , Zinc white, silica, quartz sand, quartz, white carbon,
It is made of a material such as an oxide such as diatomaceous earth, a sulfide such as molybdenum disulfide, or a metal powder. Among them, glass beads, talc, and titanium oxide are preferable in terms of price and performance. The higher the content of the particulate filler, the better to achieve the environmental stability of the laser focus, but the excessive content degrades the extrudability and moldability, and further lowers the mechanical strength. Also, if the content is too small, the environmental stability of the laser focus is not exhibited. Therefore, the content of the particulate filler is 5 to 100 parts by weight of the liquid crystalline polymer (A).
100 parts by weight, preferably 10 to 80 parts by weight.

In the present invention, the average fiber diameter is 0.5 to 20 μm.
fibrous filler (C) having an average aspect ratio of 10 or less
Various organic fibers such as glass milled fiber, carbon milled fiber, wollastonite, whisker, metal fiber, inorganic fiber and ore fiber can be used. As the carbon milled fiber, a PAN-based fiber using polyacrylonitrile as a raw material and a pitch-based fiber using pitch as a raw material are used. As whiskers, silicon nitride whiskers, silicon trinitride whiskers, basic magnesium sulfate whiskers, barium titanate whiskers, silicon carbide whiskers, boron whiskers, etc. are used.
Fibers such as brass, aluminum and its alloys, and lead are used. As the inorganic fibers, rock wool, zirconia,
Various fibers such as alumina silica, potassium titanate, barium titanate, silicon carbide, alumina, silica, and blast furnace slag are used. As ore-based fibers, asbestos, wollastonite and the like are used. Among them, milled fiber and wollastonite are preferable from the viewpoint of performance. As the milled fiber, in addition to a normal milled fiber, a milled fiber coated with a metal such as nickel or copper, a silane fiber, or the like can be used.
In this case, if the average aspect ratio exceeds 10, the anisotropy increases due to the influence of the fiber orientation, and the laser focus shift due to a change in the environmental temperature increases. When the content of the fibrous filler for achieving the environmental stability of the laser focus is large, the extrudability and the moldability are deteriorated when the content is large, and further, the environmental stability of the laser focus is not expressed. If the amount is small, the mechanical strength is reduced. Therefore, the content of the fibrous filler is 5 to 100 parts by weight, preferably 10 to 70 parts by weight, per 100 parts by weight of the liquid crystalline polymer (A).
Parts by weight.

In this case, the particulate filler (B) is useful for improving the environmental stability of the laser focus, but when the content is too large, the extrudability and the moldability are deteriorated and the material becomes brittle. The fibrous filler (C) serves to improve the mechanical properties, but the content increases the anisotropy of the material and reduces the environmental stability of the laser focus. Therefore, the total content of the components (B) and (C) needs to be 150 parts by weight or less, preferably 110 parts by weight or less.

Further, in order to improve the mechanical properties, the composition may further contain 5 to 100 parts by weight of a fibrous filler (D) having an average fiber diameter of 5 to 20 μm and an average aspect ratio of 15 or more. The content of the fibrous filler (D) is preferably from 10 to 50 parts by weight in order to have an average aspect ratio larger than that of the component (C) and increase the anisotropy. If the amount exceeds 100 parts by weight, the environmental stability of the laser focus decreases, which is not preferable. As the fibrous filler (D), glass fiber, carbon fiber and the like can be used. As the carbon fiber, a PAN-based fiber using polyacrylonitrile as a raw material and a pitch-based fiber using pitch as a raw material are used. Among them, glass fiber is preferable in terms of price and performance. When the component (D) is further added, the total content of the filler must be 150 parts by weight or less, preferably 110 parts by weight or less.

The fibrous filler and granular filler used in the present invention can be used as they are, but commonly used known surface treatment agents and sizing agents can be used in combination.

A nucleating agent, a pigment such as carbon black, an antioxidant, a stabilizer,
A composition to which additives such as a plasticizer, a lubricant, a release agent and a flame retardant are added to impart desired properties is also included in the range of the liquid crystal polymer composition according to the present invention.

The liquid crystalline polymer composition of the present invention is excellent in environmental stability of laser focus without compromising mechanical properties by compensating for each disadvantage by using two or more kinds of fillers. A material is obtained, and furthermore, the fillers in the molded body are uniformly dispersed, and a higher performance is exhibited in a dispersed state in which the particulate filler is present between the fiber fillers.

In order to produce such a liquid crystalline polymer composition, both components may be contained in the above composition ratio and kneaded. Usually, the mixture is kneaded by an extruder, extruded into pellets, and used for injection molding, but is not limited to kneading by such an extruder.

[0016]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. The evaluation method and the like are as follows. (Amount of fluctuation of laser optical axis) An optical pickup is molded, a laser beam is oscillated on the molded product, and the laser is reflected on the measurement reflection surface. The reflected laser was projected on a screen, the distance from the reference origin was measured, and the deviation of the inclination of the measured reflection surface was determined. (Vibration control) thickness 1.6mm, width 10mm, length 200m
Using a molded product of m, measurement was performed in accordance with JIS G0602 “Test method for vibration damping characteristics of damping steel sheet”, and a frequency of 100 to
The evaluation was performed based on the loss coefficient at 1500 Hz. Since the reciprocal of the loss coefficient is proportional to the number of vibrations at the time of vibration, the smaller the reciprocal of the loss coefficient, the faster the vibration subsides (the better the vibration damping property), and the larger the loss coefficient, the better the vibration damping property. (Low burrs) Using a mold in which burrs having a thickness of 20 μm are generated on the circumference of a disk (central pin gate) having a thickness of 3 mm and a diameter of 80 mm, molding is performed at the minimum filling pressure, and the burr length at that time is 2 Measured with a five-dimensional size measuring instrument. (Average aspect ratio) The pellets were heated to thermally decompose and remove the resin, and the residue was observed and evaluated using a magnifying glass. The length of fifty randomly selected fibrous fillers was measured.

Examples 1 and 2 and Comparative Examples 1 to 3 A liquid crystalline polyester (LCP; Vectra E950i, manufactured by Polyplastics Co., Ltd.) or 100 parts by weight of a polyphenylene sulfide resin (PPS) is mixed with various fillers (silica, Glass beads, calcium carbonate, and glass fibers (chopped strands, length 7 mm) were dry-blended at the ratios shown in Table 1 and then melt-kneaded with a twin-screw extruder to form pellets. The test piece was prepared from the pellet by an injection molding machine and evaluated, and the results shown in Table 1 were obtained.

[0018]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 7/10 C08K 7/10 C08L 77/12 C08L 77/12 G11B 7/12 G11B 7/12 (72) Inventor Mineo Otake 973 Miyajima, Fuji City, Shizuoka Prefecture F-term in Polyplastics Co., Ltd. DL007 DL008 FA047 FA048 FA067 FA086 FD016 FD017 FD018 GS00 5D119 AA50 BA01 JA43 JA46 JC06

Claims (8)

[Claims] 1. A liquid crystalline polymer (A) 100 parts by weight,
5 to 1 granular filler (B) having an average particle size of 0.1 to 50 μm
00 parts by weight, and fibrous filler (C) having an average fiber diameter of 0.5 to 20 μm and an average aspect ratio of 10 or less are 5-1 to 5: 1.
A liquid crystalline polymer composition for an optical pickup, comprising 00 parts by weight and having a total filler content of 150 parts by weight or less. 2. The liquid crystal polymer (A) further comprises 5 to 100 parts by weight of a fibrous filler (D) having an average fiber diameter of 5 to 20 μm and an average aspect ratio of 15 or more based on 100 parts by weight of the liquid crystalline polymer (A). The liquid crystalline polymer composition according to claim 1, wherein 3. The liquid crystalline polymer composition according to claim 1, wherein the fibrous filler (C) is at least one selected from milled fiber and wollastonite. 4. The liquid crystalline polymer composition according to claim 1, wherein the granular filler (B) is at least one selected from talc and titanium oxide. 5. The liquid crystalline polymer composition according to claim 1, wherein the particulate filler (B) is glass beads. 6. The liquid crystalline polymer composition according to claim 1, wherein the particulate filler (B) is silica. 7. The liquid crystal polymer composition according to claim 1, wherein the liquid crystal polymer (A) is a polyesteramide. 8. An optical pickup manufactured from the liquid crystalline polymer composition according to claim 1.