JPH06176522A - Hub for optical disk - Google Patents

Abstract

(57) [Summary] [Purpose] There is no cracking after molding, and there is no increase in birefringence of the optical disk, deformation of the hub, or cracking due to changes in various environmental conditions, and long-term use is possible. An optical disk hub is provided. In an optical disk hub made of an aromatic polycarbonate resin-based molded product having a metal plate built-in, the resin is 0.2 to 10 parts by weight of a specific polyolefin and an acrylic ester-based two-stage graft per 100 parts by weight of the polycarbonate resin. A hub for an optical disk, which is a polycarbonate resin composition obtained by mixing 0.5 to 10 parts by weight of an elastic polymer.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a hub made of metal is known as an optical disk hub. To directly attach the metal hub to an optical disk substrate, an adhesive is used or a screw is used. Was used. However, in such a case, there are problems that the optical disc substrate is distorted due to changes in various environmental conditions such as temperature changes in the drive device, birefringence is increased, and erroneous reading or unreadable recording occurs. For the purpose of solving such a problem, 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 substrate material with a multi-stage polymer have been proposed (Japanese Patent Laid-Open No. 6-58242).
3-251982). However, in the case of the former composite hub, for example, there were initial and short-term problems that the hub was deformed or cracked due to the 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 there are practical problems such as cracks in the hub in the durability test by the heat and humidity test, and hub cracks that make the optical disk unusable. there were.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a material for an optical disk hub which does not have initial and short-term problems and which can be used for a long period of time. It is to provide an excellent hub for polycarbonate resin optical disks.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, as a resin used for a hub for an optical disk, an aromatic polycarbonate is mainly used, and a polyolefin and an acrylic ester-based resin 2 are used. A resin composition containing a step-grafted elastic polymer does not cause deformation or cracking of the hub due to stress in the hub caused by changes in various environmental conditions, and is extremely effective in solving the problem. The present invention has been achieved by finding that it is objective.

The present invention relates to an optical disk hub made of a polycarbonate resin molded product containing a metal plate,
The resin is 100 parts by weight of the polycarbonate resin,
Polycarbonate resin prepared by blending 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 acrylic ester type 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 a dihydric phenol.
4,000-100,000, preferably 18,000
~ 40,000 aromatic polycarbonate resin,
Usually, it is produced by reacting a dihydric phenol and a carbonate precursor by a solution method or a melting method. Typical examples of the dihydric phenol 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 Examples thereof include-(4-hydroxyphenyl) cyclohexane and bis (4-hydroxyphenyl) oxide. A preferred dihydric phenol is a bis (4-hydroxyphenyl) alkane, particularly bisphenol A as a main raw material.

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

Polyethylene, polypropylene and / or polymethylpentene, which are the polyolefins used in the present invention, may be those which are usually commercially available, but those having a melting property close to that of a polycarbonate resin are preferred.

The acrylic ester type two-stage graft elastic polymer used in the present invention comprises an acrylic ester as a main component, and an acrylic elastic polymer having an acrylic rubber obtained by emulsion-polymerizing butadiene and a cross-linking agent as a trunk component. Specifically, acrylic acid ester 3 such as 2-ethylhexyl acrylate, n-butyl acrylate, etc.
5 to 60 parts by weight (54 to 92% by weight) butadiene 5 to 2
0 parts by weight (8 to 31% by weight), methyl methacrylate 0
.About.15 parts by weight (0 to 15% by weight) and a crosslinking agent (eg ethylene dimethacrylate) 0.6 to 1.3 parts by weight (0.
(9 to 2.0% by weight) is added to a rubber latex obtained by emulsion polymerization to obtain an average particle diameter of 0.13 to 0.20 μ.
65 parts by weight (100% by weight) of the latex-like rubber adjusted to
15 parts by weight, 5 to 10 parts by weight of methyl methacrylate, 0 to 10 parts by weight of acrylonitrile, a cross-linking agent (for example, ethylene dimethacrylate, divinylbenzene, etc.) 0.1
20 to 25 parts by weight of a mixed monomer consisting of 0.3 parts by weight is graft-polymerized, 10 to 15 parts by weight of methyl methacrylate as a second stage graft component, and a cross-linking agent (for example, ethylene dimethacrylate, divinylbenzene) 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 parts by weight.

Such an acrylic ester type two-stage graft elastic polymer is commercially available from Kureha Chemical Industry Co., Ltd. as HIA-15 and can be easily obtained. In the present invention, the compounding ratio is 0.2 to 5 parts by weight, and 0.5 to 5 parts by weight, respectively, for the polyolefin and the acrylic ester type two-stage graft elastic polymer with respect to 100 parts by weight of the polycarbonate resin.
10 to 10 parts by weight, and more preferably 0.5 to
3 parts by weight, 1 to 10 parts by weight.

Whether the compounding amount of the polyolefin and the acrylic ester type two-stage graft elastic polymer is more or less than the above range, the hub generated by the characteristics of the resin composition of the present invention, that is, various environmental conditions. The internal stress does not have the effect of preventing the hub from being deformed or cracked, and further lowers the heat resistance, causes the appearance failure due to layer peeling, and the adhesive strength in the case of solvent bonding. It is insufficient and not preferable.

The polycarbonate resin composition used in the present invention may contain other additives such as a strengthening agent, a heat stabilizer, an antioxidant, a light stabilizer, a release agent and an antistatic agent for the purpose of modification. It can be blended.

As the method for producing the resin composition of the present invention, for example, a polycarbonate resin, a polyolefin, and an acrylic ester type two-stage graft elastic polymer are uniaxial extruder, biaxial extruder, Banbury mixer, kneading roll, Brabender. A method of melt kneading under predetermined heating using a kneader such as a kneader. Among them, the method using a single screw extruder or a twin screw extruder is preferable.

On the other hand, regarding 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 material is appropriately selected and incorporated into the hub by insert molding. The present invention will be 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 product.

[0015]

[Examples 1 to 3] Pre-dried polycarbonate resin {Panlite L-1225 manufactured by Teijin Kasei Co., Ltd .; indicated by PC in Table 1} 100 parts by weight of the polyolefin in the amount shown in Table 1 {Mitsui Petrochemical Co., Ltd. ) Hi-Zex 2100J
P; indicated by PO in Table 1} 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 with 30 mmφ. It melt-extruded and pelletized by the machine (VSK-30 made from Nakatani Machine). The pellets obtained were dried at 120 ° C for 5 hours, and the melted material was used as a hub metal plate (diameter 22 mm, thickness 0.5 m).
m) was set by insert injection molding to obtain an optical disk hub (diameter: 25 mm, thickness: 2.3 mm), and its characteristics were evaluated.

As a durability test, a constant temperature and humidity chamber (Tabay Co., Ltd .; Platinum Subzero Lucifer PSL)
-2G) at 80 ° C. × 85% RH × 2000 hours for evaluation of cracks, breakage, etc., and the results are shown in Table 1.

[0017]

Comparative Examples 1 and 2 Table 1 shows the evaluation results of 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] A resin composition using a multistage polymer (BTA manufactured by Kureha Chemical Industry Co., Ltd .; indicated by GP in Table 1) was obtained in the same manner as in Examples 1 to 3. Table 1 shows the evaluation results of the optical disk hub.

[0019]

[Table 1]

[0020]

EFFECTS OF THE INVENTION The optical disk hub of the present invention uses the special polycarbonate resin composition, so that the birefringence of the optical disk is increased and the hub is deformed or cracked due to changes in various environmental conditions. It can be used for a long period of time and is extremely useful industrially.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Nagata 184-1 Maioka-cho, Totsuka-ku, Yokohama-shi, Kanagawa

Claims (1)

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