JPH0636440A - Cartridge for optical recording medium - Google Patents

Abstract

PURPOSE:To substantially prevent the attraction of dust and to decrease malfunctions by allowing a specific antistatic agent to exist in materials constituting the cartridge. CONSTITUTION:The antistatic agent of an aliphat. sulfonate type is added to the base materials used for the cartridge for optical recording media, for example, thermoplastic resins, such as polycarbonate, polymethyl methacrylate and ABS resins. The outdoor flows into the cartridge from its aperture during the operation of the optical disk. This outdoor air is brought into contact in the form of high-velocity air flow with the cartridge by the rotating optical disk and is discharged again from another aperture. The antistatic agent property is imparted to the cartridge at this time, by which the sticking of the external dust to the cartridge is prevented and the malfunctions of the optical disk by the stuck dust are decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc cartridge for accommodating an optical recording medium such as an optical disc, and more particularly to a disc cartridge for an optical recording medium which is less likely to have dust attached and which is suitable for reducing erroneous recording and reproducing operations of the optical disc.

[0002]

2. Description of the Related Art Conventionally, a cartridge of this type, for example, an optical disk cartridge, is generally composed of a molded product of a thermoplastic resin such as a polycarbonate resin or an ABS resin, but this molded product has a high surface electric resistivity. , It is easy to attach dust in the air due to being charged with static electricity, and this adhered substance is transferred to the surface of the optical disc housed inside, which causes the recording / playback light to be reflected and not recorded (writing error), Or, due to diffused reflection, a malfunction such as an erroneous reproduction of a signal (readout error) occurs.

[0003]

In order to prevent this, an optical disk cartridge is housed in which an optical disk is housed.
The structure is hermetically sealed from the outside except when it is mounted on the drive (Actual No. 57-33484). However, since the optical disk rotates at a high speed during operation, it is easily charged, and a method has already been proposed in which the surface of the optical disk is made conductive so as to prevent the adsorption of dust due to this charging, and the charge is discharged to the device side.

However, during the operation of the optical disk, the outside air flows in from the cartridge opening, the rotating optical disk makes a high-speed air flow, comes into contact with the surface of the cartridge, and again flows out from another opening, so that external dust constantly flows in.
Dust tends to be adsorbed on the surface of the cartridge, and this dust falls and adheres to the surface of the optical disc, which causes a malfunction during recording and reproduction.

[0005]

In view of the above problems of the optical disk cartridge, the present inventors provide a cartridge for an optical recording medium which eliminates dust electrostatically adsorbed on the surface of the cartridge and reduces malfunction of the optical disk. As a result of intensive studies to achieve the above, it was found that the presence of a specific antistatic agent on the surface of a cartridge base material for an optical recording medium made of a thermoplastic resin can solve the above problems, and the present invention has been completed. It was

The gist of the present invention is an optical recording medium cartridge made of a thermoplastic resin for accommodating an optical recording medium.
A cartridge for an optical recording medium is characterized in that an aliphatic sulfonate type antistatic agent is present on the surface of the cartridge. Hereinafter, the present invention will be described in more detail. Examples of the base material used in the cartridge for an optical recording medium in the present invention include thermoplastic resins such as polycarbonate, polymethylmethacrylate, ABS resin, and amorphous polyolefin, and polycarbonate resin is particularly preferably used. Examples of the antistatic agent used in the present invention include aliphatic sulfonate type antistatic agents. Examples of the aliphatic sulfonate-type antistatic agent include

[0007]

Embedded image Higher aliphatic sulfonate represented by R ₁ —SO ₃ X (I)

[0008]

[Chemical 2] Sulfonated higher fatty acid salt represented by

[0009]

Embedded image R ₁ —COOR ₃ —SO ₃ X (III) represents a higher aliphatic ester sulfonate.

[0010]

Embedded image R ₁ —O—R ₃ —SO ₃ X ... (IV) higher ether sulfonate

[0011]

[Chemical 5] Wherein R ₁ is a higher aliphatic group, X is an alkali metal or alkaline earth metal, R ₂ is hydrogen or a lower alkyl group, R ₃ is a divalent lower aliphatic group, R ₄ is hydrogen or A (higher) aliphatic group, which may be the same as or different from R ₁ .

In the above general formulas (I) to (V), R ₁
Examples thereof include a hexyl group, an octyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a pentadecyl group, a hexadecyl group, a hexadecylene group, a heptadecyl group and an octadecyl group, and R ₂ is hydrogen or a methyl group, an ethyl group. Examples of R ₃ include methylene group, ethylene group, propylene group, tetramethylene group, 2-hydroxytrimethylene group and the like. Examples of X include sodium, potassium, calcium, magnesium and the like.

These aliphatic sulfonate type antistatic agents include sodium dodecyl sulfonate, sodium tetradecyl sulfonate, sodium hexadecyl sulfonate, sodium octadecyl sulfonate or a mixture thereof, sodium salt of dioctyl sulfosuccinate, Sodium salt of bis (dodecyl) sulfosuccinate,
Examples thereof include sodium salt of bis (octadecyl) sulfosuccinate or a mixture thereof.

Among these, alkyl sulfonate Na
Salts, Na salts of dialkyl sulfosuccinates are preferred. The above-mentioned aliphatic sulfonate type antistatic agent may be used by coating on the surface of the cartridge for optical recording medium, but from the viewpoint of long-term sustainability of the antistatic effect, it is blended in the raw material resin forming the cartridge. It is desirable to use.

When the antistatic agent is blended in the resin for the cartridge and used, the blending amount is 100% of the thermoplastic resin.
Usually 0.1 to 5 parts by weight, preferably 0.
It is in the range of 5 to 3 parts by weight. If the compounding amount is small, the effect of improving the antistatic property is small, and conversely, if it is large, the moldability is deteriorated, which is not preferable. If desired, known additives such as a colorant, an antioxidant, an ultraviolet absorber, and a heat stabilizer may be added to the thermoplastic resin together with the antistatic agent.

In order to manufacture the cartridge of the present invention, first, each component of the above-mentioned thermoplastic resin, antistatic agent and other additives is dry blended, or a general kneading machine such as Banbury mixer, Henschel is used. mixer,
The mixture is melt-kneaded by an extruder or the like, and the kneaded product is extruded and pelletized by cutting or the like, or pulverized to have a predetermined particle size to obtain a molding material. Then, a cartridge molded product for an optical recording medium, generally a cartridge half, is formed by, for example, injection molding, using a mold having a predetermined shape, using the above-mentioned blended material or a pellet-shaped or granular molding material. The molding method, molding conditions and the like in this cartridge molding may be appropriately determined according to the shape of the cartridge, the type of resin used, and the like. When a polycarbonate resin is used as the resin, it is preferable to use one having a molecular weight (viscosity average molecular weight) in the range of 14000 to 25000, and to keep the resin temperature in the range of 220 to 300 ° C. for molding.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 To 100 parts by weight of a bisphenol A type polycarbonate resin having a molecular weight of 21,000, 1 part by weight of an antistatic agent (Na salt alkyl group R ₁ : C _{8 to} C ₁₀ main component of Erest PC2 alkyl sulfonate manufactured by Kao Soap Co., Ltd.) was added, After dry blending, the mixture was kneaded (melt-kneaded) at 260 ° C. by a twin-screw extruder to form extruded pellets. The pellets are molded at a temperature of 270
Injection molding was performed at 0 ° C. to mold an optical disk cartridge half. Moldability during the injection molding and initial and life test of the obtained cartridge half (80 ° C., 80% R
The antistatic property after the H 500 hr acceleration test) was evaluated by the following method. The results are shown in Table-1.

(1) Moldability The quality of moldability at the time of molding and presence / absence of bleed-out on the surface of the molded product are evaluated in three grades of ○ (good), △ (somewhat bad), and × (bad) (2) Surface resistivity The surface resistivity of the cartridge surface was measured according to ASTM D257. (3) Half-life A voltage of 10 KV was applied to the cartridge half, and the half-life was measured with a static onest meter. (4) Dust adhesion status As a dust adhesion test device, a dirt chamber device manufactured by Ueki Kosakusho Co., Ltd. is used, and the temperature inside the dirt chamber is 25
C, humidity was 45 to 50 RH%, wind speed was 0.7 m / s, Kanto loam powder was used as dust powder, and the cleanliness inside the dirt chamber was set to class 5,000,000 or more. Put the cartridge half in this dirt chamber,
After holding for 30 minutes, the surface of the cartridge half was visually observed, and the degree of contamination was visually evaluated by dividing it into 5 stages from A to E. In this case, A is the least pollutant and E
Is the largest.

Example 2 Example 1 was repeated except that the amount of the antistatic agent was increased to 2 parts by weight. The results are shown in Table-1.

Comparative Example 1 The procedure of Example 1 was repeated except that no antistatic agent was added. The results are shown in Table-1.

Comparative Example 2 In Example 1, the kind of the antistatic agent is a phosphonium sulfonate having the following structural formula (MKP5 manufactured by Takemoto Yushi Co., Ltd.).
No. 02) was mixed with 5 parts by weight, and the same procedure was performed. The results are shown in Table-1.

[0022]

[Chemical 6]

[0023]

[Table 1]

[0024]

The cartridge of the present invention is excellent in antistatic property and does not adsorb dust, so that the surface of the optical disk is not polluted. Therefore, an optical recording medium with less post-operation can be obtained.

Claims (1)

[Claims] 1. An optical recording medium cartridge made of a thermoplastic resin for accommodating an optical recording medium, wherein an aliphatic sulfonate type antistatic agent is present on the surface of the cartridge. Cartridge for.