JP2703473B2 - Hub for optical disc - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hub for an optical disk.

[0002]

2. Description of the Related Art Hitherto, as a hub for an optical disk, a hub made of metal is known, and such a metal hub is directly attached to an optical disk substrate by a method such as using an adhesive or screwing. Was used. However, in such a case, the optical disk substrate is distorted due to changes in various environmental conditions such as a change in temperature in the driving device, and the birefringence increases. For the purpose of solving such a problem, there has been proposed a composite hub of a substrate material, that is, a polycarbonate resin and a metal plate, and a composite hub of a resin and a metal plate obtained by blending a multi-stage polymer with the substrate material (Japanese Patent Application Laid-Open No. Sho.
3-251982). However, in the case of the former composite hub, for example, there is an initial and short-term problem that the hub is deformed or cracked due to a difference in shrinkage between the polycarbonate resin and the metal plate due to cooling after molding. In the latter case, there are no such initial and short-term problems, but practical problems such as cracking of the hub in the endurance test by the wet heat test and cracking of the hub, making it impossible to use the optical disk. there were.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a material for an optical disk hub which is free from initial and short-term problems and which can be used for a long period of time. An object of the present invention is to provide an excellent polycarbonate resin optical disc hub.

[0004]

The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the resin used for the optical disk hub is mainly composed of an aromatic polycarbonate, a polyolefin and an acrylic ester-based resin. The resin composition containing the step graft elastic polymer is extremely effective in solving the problems without the stress in the hub caused by changes in various environmental conditions causing the hub to deform or crack. And found the present invention.

The present invention relates to an optical disk hub made of a polycarbonate resin molded article having a built-in metal plate.
The resin, per 100 parts by weight of the polycarbonate resin,
Polycarbonate resin obtained by mixing 0.2 to 10 parts by weight of at least one polyolefin selected from the group consisting of polyethylene, polypropylene and polymethylpentene and 0.5 to 10 parts by weight of an acrylic acid ester-based two-stage graft elastic polymer A hub for an optical disk, which is a composition.

The polycarbonate resin used in the present invention has a viscosity average molecular weight of 1 derived from dihydric phenol.
4,000 to 100,000, preferably 18,000
~ 40,000 aromatic polycarbonate resins,
Usually, it is produced by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method. Representative examples of dihydric phenols include 2,2-bis (4-hydroxyphenyl) propane (hereinafter abbreviated as bisphenol A), bis (4-hydroxyphenyl) methane, 2,2
-Bis (3,5-dimethyl-4-hydroxyphenyl)
Propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, 1,1 -(4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) oxide and the like. Preferred dihydric phenols are those based on bis (4-hydroxyphenyl) alkane, especially bisphenol A.

Examples of the carbonate precursor include carbonyl halide, carbonyl ester and haloformate, and specific examples thereof include phosgene, diphenyl carbonate, dihalogenated haloformate and mixtures thereof. In producing polycarbonate,
The dihydric phenol may be used alone or in combination of two or more. In addition, an appropriate molecular weight modifier, a branching agent, a catalyst for accelerating the reaction, and the like can be used. Two or more aromatic polycarbonate resins thus obtained may be mixed.

The polyolefin used in the present invention, polyethylene, polypropylene and / or polymethylpentene, may be a commercially available one, but preferably has a melting property close to that of a polycarbonate resin.

The acrylic ester-based two-stage graft elastic polymer used in the present invention has an acrylic ester as a main component and an acrylic rubber as a main component comprising an acrylic rubber obtained by emulsion polymerization of butadiene and a crosslinking agent. And specifically, acrylates 3 such as 2-ethylhexyl acrylate and n-butyl acrylate.
5 to 60 parts by weight (54 to 92% by weight) butadiene 5-2
0 parts by weight (8 to 31% by weight), methyl methacrylate 0
To 15 parts by weight (0 to 15% by weight) and 0.6 to 1.3 parts by weight of a crosslinking agent (for example, ethylene dimethacrylate).
(9 to 2.0% by weight), and a coagulant is added to a rubber latex obtained by emulsion polymerization of the rubber latex to obtain an average particle size of 0.13 to 0.20 μm.
With 65 parts by weight (100% by weight) of latex rubber adjusted to the above, styrene 5
15 parts by weight, 5 to 10 parts by weight of methyl methacrylate, 0 to 10 parts by weight of acrylonitrile, 0.1 to 0.1% of a crosslinking agent (for example, ethylene dimethacrylate, divinylbenzene, etc.)
Graft polymerization of 20 to 25 parts by weight of a mixed monomer consisting of 0.3 parts by weight is carried out, and 10 to 15 parts by weight of methyl methacrylate as a second stage graft component, and a crosslinking agent (for example, ethylene dimethacrylate, divinylbenzene, etc.) 0.1
It is a multi-component copolymer resin produced by graft polymerizing 10 to 15 parts by weight of a mixed monomer consisting of 0.3 to 0.3 parts by weight.

Such an acrylic ester-based two-stage graft elastic polymer is commercially available as HIA-15 from Kureha Chemical Industry Co., Ltd., and can be easily obtained. In the present invention, the blending ratio is such that the polyolefin and the acrylate-based two-stage graft elastic polymer are 0.2 to 5 parts by weight and 0.5 to 0.5 part by weight, respectively, based on 100 parts by weight of the polycarbonate resin.
To 10 parts by weight, more preferably 0.5 to 10 parts by weight, respectively.
3 parts by weight, 1 to 10 parts by weight.

Regardless of whether the blending amount of the polyolefin and the acrylate-based two-stage graft elastic polymer is larger or smaller than the above range, the properties of the resin composition of the present invention, that is, the hub formed due to changes in various environmental conditions. The effect of preventing internal stress from causing deformation or cracking of the hub cannot be obtained, and further, heat resistance is reduced, appearance defects due to delamination occur, and adhesive strength in the case of solvent bonding. Shortage is not preferred.

The polycarbonate resin composition used in the present invention contains other additives such as a reinforcing agent, a heat stabilizer, an antioxidant, a light stabilizer, a release agent, and an antistatic agent for the purpose of modification. Can be blended.

The method for producing the resin composition of the present invention includes, for example, a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneading roll, a Brabender And a method of melt-kneading under predetermined heating using a kneader such as a kneader. Among them, a method using a single screw extruder or a twin screw extruder is preferable.

On the other hand, as for the metal plate which is another component of the optical disk hub of the present invention, the kind and shape of the metal are not particularly limited. A suitable one is selected as appropriate, and is incorporated into the hub by insert molding. The present invention is described in more detail by the following examples. The presence or absence of peeling of the initial characteristics in the examples indicates the presence or absence of layer peeling of the molded article.

[0015]

Examples 1 to 3 Polycarbonate resin previously dried (Panlite L-1225 manufactured by Teijin Chemicals Ltd .; indicated by PC in Table 1) Polyolefin having an amount shown in Table 1 per 100 parts by weight (Mitsui Petrochemical Co., Ltd.) ) HIZEX 2100J
P: In Table 1, indicated by PO and an acrylic elastic polymer {HIA-15, manufactured by Kureha Chemical Industry Co., Ltd .; indicated by AE in Table 1,}, mixed using a V-type blender, and extruded by 30 mmφ. The mixture was melt extruded into pellets using a machine (VSK-30 manufactured by Nakatani Machinery). The obtained pellets were dried at 120 ° C. for 5 hours, and the melt was transferred to a hub metal plate (diameter 22 mm, thickness 0.5 m).
m) was injection-molded into a mold in which a hub for an optical disk (diameter 25 mm, thickness 2.3 mm) was obtained, and its characteristics were evaluated.

As a durability test, a thermo-hygrostat (manufactured by Tabai Co., Ltd .; Platinum Subzero Lucifer PSL)
-2G) at 80 ° C. × 85% RH × 2000 hours to evaluate cracks, cracks and the like.

[0017]

Comparative Examples 1 and 2 Table 1 shows the evaluation results of the optical disk hubs obtained by using the resin compositions shown in Table 1 in the same manner as in Examples 1 to 3.

[0018]

Comparative Example 3 In the same manner as in Examples 1 to 3, a multistage polymer (BTA manufactured by Kureha Chemical Industry Co., Ltd .; GP in Table 1) was used to obtain a resin composition. Table 1 shows the evaluation results of the optical disk hub.

[0019]

[Table 1]

[0020]

The optical disk hub of the present invention uses a special polycarbonate-based resin composition so that the birefringence of the optical disk increases, the hub deforms, and cracks occur even when various environmental conditions change. It can be used for a long period of time and is extremely useful industrially.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-251982 (JP, A) JP-A-5-41053 (JP, A) JP-A-3-283154 (JP, A) 193376 (JP, U)

Claims (1)

(57) [Claims] 1. An optical disc hub comprising an aromatic polycarbonate resin-based molded article containing a metal plate, wherein said resin is at least one selected from the group consisting of polyethylene, polypropylene and polymethylpentene per 100 parts by weight of polycarbonate resin. A hub for an optical disc, characterized by being a polycarbonate resin composition obtained by mixing 0.2 to 10 parts by weight of polyolefin and 0.5 to 10 parts by weight of an acrylic ester-based two-stage graft elastic polymer.