JP4316321B2 - Disc guide parts for disc drives - Google Patents

Description

  The present invention relates to a disk guide component in a disk drive device such as a CD and a DVD. More specifically, the present invention relates to a disk guide component formed of a specific resin material.

  In the slot-in type disk drive device, a guide part for guiding insertion and / or ejection of a recording disk mainly made of polycarbonate resin is provided. Such a disk guide part is for transporting the disk while sandwiching the disk in cooperation with the feed roller, and suppresses rattling of the disk by pressing the vicinity of the outer periphery of the disk when the disk is inserted or ejected. , Has the function of helping to smoothly insert or eject the disc.

  Conventionally, such disc guide parts are formed of a resin material, and in particular, a general-purpose grade of polyacetal resin is often used as it is.

There are only a few documents that mention the material forming the disk guide component, and only a few documents describe the fact that the disk guide is made of resin (Patent Document 1).
JP 2003-59151 A ([0006] column)

  However, the mechanism of the disc guide component formed of a resin material that has been conventionally used is not always clear, but the disc may be slightly scratched during repeated insertion or ejection of the disc. Such scratches are likely to occur not on the recording surface of the disc, but on the opposite side, the so-called label surface, near the outer periphery of the disc, so it is considered that there is little possibility of particularly affecting the recording / reproducing performance of the disc, For example, if the insertion / ejection is reversed upside down due to a human error or the like, the recording surface may be damaged. Further, the occurrence of these scratches impairs the commercial value and appearance, and improvement has been demanded.

  As a result of intensive investigations to solve such problems, the present inventors have been able to remarkably improve the occurrence of scratches on polycarbonate discs by forming disc guide parts with a resin composition comprising a combination of specific polyacetal resins. And found the present invention.

  That is, the present invention is a slot-in type characterized by being formed of a polyacetal resin composition comprising 100 parts by weight of a linear polyacetal resin (A) and 0.1 to 20 parts by weight of a branched or cross-linked polyacetal resin (B). The present invention relates to a disk guide part of a disk drive device.

  Hereinafter, the present invention will be described in detail. The disk guide component 1 of the slot-in type disk drive apparatus according to the present invention has a cross-sectional shape as shown in FIG. 1 and is generally used in conjunction with the rubber roll 3 and the like when the recording disk 2 is inserted and / or ejected. 2 is guided in the form as shown in FIG. Such a disk guide component is generally an integral shape as shown in FIG. 1, but it is also possible to form a divided shape and guide only the periphery of the contact portion with the disk.

  The present invention is characterized in that such a disk guide part is formed of a polyacetal resin composition comprising 100 parts by weight of a linear polyacetal resin (A) and 0.1 to 20 parts by weight of a branched or cross-linked polyacetal resin (B). To do. The effect of the guide component having such a configuration is particularly remarkable when the recording disk is based on a polycarbonate resin.

First, the linear polyacetal resin (A) used in the present invention is a polymer compound having a substantially linear molecular structure having an oxymethylene group (—CH ₂ O—) as a main structural unit. Any of a polymer and a copolymer (including a block copolymer) containing a small amount of other constituent units in addition to the oxymethylene group may be used, but it is particularly preferable to use a copolymer.

  The copolymer is preferably obtained by copolymerizing 99.9 to 95.0% by weight of trioxane (a) with 0.1 to 5.0% by weight of a compound (b) selected from a monofunctional cyclic ether compound and a monofunctional cyclic formal compound. The melt index is preferably 1 to 50 g / min. In addition, the melt index prescribed | regulated in this application is measured on condition of 190 degreeC and a load of 2160g according to ASTMD-1238.

  Trioxane (a), which is a main raw material used in the production of the polyacetal copolymer, which is preferable as the linear polyacetal resin (A), is a cyclic trimer of formaldehyde. It is obtained by reacting and used after being purified by a method such as distillation. The trioxane (a) used for the polymerization is preferably one containing as little impurities as possible such as water, methanol and formic acid.

  The compound (b) selected from a monofunctional cyclic ether compound and a monofunctional cyclic formal compound used for producing a polyacetal copolymer by copolymerizing with the trioxane (a) is a cyclic ether unit in one molecule. Or a compound having one cyclic formal unit and not forming a branched structure by ring-opening polymerization, ethylene oxide, 1,3-dioxolane, tetrahydrofuran, trioxepane, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, tri Examples include ethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and the like. Among these, it is preferable to use one or more selected from the group consisting of ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal and diethylene glycol formal.

  The production method of the linear polyacetal resin (A) used in the present invention is not particularly limited, and can be produced by a conventionally known production method. For example, in the case of a polyacetal copolymer, it can be obtained by adding an appropriate amount of molecular weight regulator to the above trioxane (a) and compound (b), and performing cationic polymerization using a cationic polymerization catalyst. Deactivation treatment, unstable terminal treatment, stabilization treatment with a stabilizer, and the like may be performed.

Next, the branched or crosslinked polyacetal resin (B) used in the present invention is branched or crosslinked in an oxymethylene (—CH ₂ O—) repeating unit by copolymerizing components capable of forming a branched structure or a crosslinked structure. Introducing the structure, among them, trioxane (a) 99.89-89.0% by weight, monofunctional cyclic ether compound and monofunctional cyclic formal compound (b) 0.1-10.0% by weight and polyfunctional glycidyl ether compound (c) Those obtained by copolymerizing 0.01 to 1.0% by weight are preferred, and those having a melt index of 0.1 to 10 g / min are preferred.

  Here, the compound (b) selected from the trioxane (a), the monofunctional cyclic ether compound and the monofunctional cyclic formal compound used for the production of the branched or cross-linked polyacetal resin (B) is the linear polyacetal resin (A). Compounds as detailed in the description. The compound (b) used for the production of the branched or cross-linked polyacetal resin (B) may be the same as or different from the compound (b) used for the production of the linear polyacetal resin (A).

  Further, as the polyfunctional glycidyl ether compound (c) used for the production of the branched or crosslinked polyacetal resin (B), those having two or more glycidyl ether groups can be used, but preferably 3 to 4 in one molecule. These compounds having a glycidyl ether group are specifically preferable compounds such as trimethylolpropane triglycidyl ether, glycerol triglycidyl ether and pentaerythritol tetraglycidyl ether.

  The method for producing such a branched or crosslinked polyacetal resin (B) used in the present invention is not particularly limited. For example, a branched or cross-linked polyacetal resin (B) comprising a compound (b) selected from trioxane (a), a monofunctional cyclic ether compound and a monofunctional cyclic formal compound and a polyfunctional glycidyl ether compound (c) is a monomer of these. It can be obtained by adding an appropriate amount of molecular weight regulator to the component and performing cationic polymerization using a cationic polymerization catalyst. After polymerization, the catalyst is deactivated, the unstable end is treated, and stable. What is necessary is just to perform the stabilization process etc. by an agent.

  As described above, the disk guide component of the slot-in type disk drive device according to the present invention contains 0.1 to 20 parts by weight of a branched or cross-linked polyacetal resin (B) in 100 parts by weight of the linear polyacetal resin (A) as described above. It was formed with the polyacetal resin composition obtained. Preferably, the amount of the branched or cross-linked polyacetal resin (B) is 0.2 to 10 parts by weight. Even if the amount of the branched or crosslinked polyacetal resin (B) is large or small, it is difficult to suppress the occurrence of scratches on the recording disk.

  In the composition, it is preferable to select a combination of the linear polyacetal resin (A) and the branched or cross-linked polyacetal resin (B) in which the melt index ratio satisfies the following formula.

0.02 ≦ MI _B / MI _A ≦ 1.5
(MI _A and MI _B indicate the melt index of resin (A) and resin (B), respectively)
Further, as the ratio of the melt index of the polyacetal resin melt index of the composition (MI _AB) linear polyacetal resin (A) (MI _A) satisfies the following equation, the linear polyacetal resin (A) used branch Alternatively, it is preferable to adjust the melt index and the blending ratio of the crosslinked polyacetal resin (B).

0.7 ≦ MI _A / MI _AB ≦ 1.4
(MI _A and MI _AB indicate the melt index of resin (A) and resin composition, respectively)
The polyacetal resin composition used in the present invention is basically prepared by melt-kneading a linear polyacetal resin (A) and a branched or cross-linked polyacetal resin (B). The treatment conditions are desirably melt kneading at a temperature of 180 to 270 ° C. for at least 30 seconds. The specific aspect of the preparation method is not particularly limited, and the necessary components are kneaded using a single or twin screw extruder or other melt kneading apparatus to form a pellet for molding. Equipment and method preparation methods apply.

  The polyacetal resin composition of the present invention preferably contains various stabilizers selected as necessary. Examples of the stabilizer include one or more of hindered phenol compounds, nitrogen-containing compounds, alkali or alkaline earth metal hydroxides, inorganic salts, carboxylates, and the like. Furthermore, as long as the purpose and effect of the present invention are not impaired, general additives for thermoplastic resins, for example, colorants such as dyes and pigments, lubricants, mold release agents, antistatic agents, surfactants, if necessary. Alternatively, one or more organic polymer materials, inorganic or organic fibrous, powdery, and plate-like fillers can be added.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. The evaluation was performed by the following method.
[Melt index (MI)]
According to ASTM D-1238, the measurement was performed under the conditions of 190 ° C. and a load of 2160 g.
[Copolymerization composition]
The prepared polyacetal resin was dissolved in hexafluoroisopropanol d2, and its copolymer composition was confirmed by ¹ H-NMR measurement.
[Damage to polycarbonate resin disc]
First, an evaluation test piece (φ5 mm × 15 mm, tip shape is hemisphere of r = 2.5 mm) shown in FIG. 3 was molded from a resin material to be evaluated (polyacetal resin composition).

  Next, using the Suzuki friction / wear tester, the test piece for evaluation and a polycarbonate resin CD-R disk (maxell MQ-74) were arranged as shown in FIG. 4, with a load of 9.8 N and a rotation speed of 10 mm. The sample was slid for 1000 seconds at / s, and scratches on the CD-R disc were visually evaluated. Judgment was performed in five stages according to the following criteria.

1: No occurrence of sliding marks, wire scratches, etc. 2: Extremely minute sliding marks, wire scratches occur 3: Slide marks, wire scratches occur in a part of the sliding part 4: Sliding traces and wire flaws occur on the entire sliding part 5: Sliding traces and flaws occur on the entire sliding part [Manufacture of linear polyacetal resin (A) and branched / crosslinked polyacetal resin (B) ]
Two with paddles using a continuous mixing reactor composed of a barrel that has a shape with two circular cross-sections and a rotating shaft with paddles. In the case of a linear polyacetal resin (A), the compound (b) selected from trioxane (a) and a monofunctional cyclic ether compound and a monofunctional cyclic formal compound is shown in Table 1. In the case of a branched / crosslinked polyacetal resin (B), a compound (b) selected from trioxane (a), a monofunctional cyclic ether compound and a monofunctional cyclic formal compound and a polyfunctional glycidyl ether compound (c) In addition to the ratio shown in Table 2, methylal is continuously supplied as a molecular weight regulator, and boron trifluoride is added continuously at 0.005% by weight with respect to trioxane. Was Tsu. While rapidly passing the reaction product discharged from the polymerization machine through a crusher, the catalyst was deactivated by adding it to a 60 ° C. aqueous solution containing 0.05% by weight of triethylamine. Furthermore, after separation, washing and drying, a crude polyacetal resin (linear polyacetal resin and branched or cross-linked polyacetal resin) was obtained.

  Subsequently, 3 weight% of triethylamine 5 weight% aqueous solution and pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] are added to 100 weight parts of the crude polyacetal resin. Add 0.3 wt%, melt and knead at 210 ° C in a twin screw extruder to remove unstable parts, pellet form polyacetal resins (linear polyacetal resins A1 to A3 (Table 1) and branched or cross-linked polyacetal resins B1 to B1) B3 (Table 2)) was obtained.

The polymer composition and melt index (MI) of these polyacetal resins are shown in Tables 1 and 2. The abbreviations in the table are as follows.
(b) Component
DO: 1,3-dioxolane
BF: 1,4-butanediol formal
(c): Component
TMPTGE: Trimethylolpropane triglycidyl ether Examples 1-7, Comparative Examples 1-3
The linear polyacetal resin (A) and branched or cross-linked polyacetal resin (B) produced by the above method are blended in the proportions shown in Table 3, and melt-kneaded at 210 ° C. with a twin-screw extruder to form pellet-shaped polyacetal. A resin composition was obtained. The test piece for evaluation shown in FIG. 3 was molded using this polyacetal resin composition, and the scratching property to the polycarbonate resin disk was evaluated. In the table, MI _AB is the melt sundex of the polyacetal resin composition.

  For comparison, the same evaluation was performed for the case where the branched / crosslinked polyacetal resin (B) was not added. The results are shown in Table 3.

FIG. 6 is a schematic cross-sectional view of a disk guide component as viewed from the direction of insertion or ejection of the disk. FIG. 6 is a schematic cross-sectional view showing a state when a disc is inserted or ejected. It is the schematic of the test piece for evaluation for evaluating the damage property to a disk. It is the schematic which shows the evaluation method of the damage property to a disk.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Disc guide component 2 ... Recording disc 3 ... Rubber roll

Claims (8)

A disk guide for a slot-in type disk drive device, characterized in that it is formed of a polyacetal resin composition comprising 100 parts by weight of a linear polyacetal resin (A) and 0.1-20 parts by weight of a branched or cross-linked polyacetal resin (B). parts. 2. The disc guide component according to claim 1, wherein the disc guide component is for guiding insertion and / or ejection of a recording disc based on polycarbonate resin. Branched or cross-linked polyacetal resin (B) is trioxane (a) 99.89-89.0% by weight, monofunctional cyclic ether compound and monofunctional cyclic formal compound (b) 0.1-10.0% by weight and polyfunctional glycidyl ether compound (c) The disk guide component according to claim 1 or 2, which is obtained by copolymerizing 0.01 to 1.0% by weight. 4. The disk guide component according to claim 3, wherein the polyfunctional glycidyl ether compound (c) has 3 to 4 glycidyl groups. The disc guide component according to claim 3, wherein the polyfunctional glycidyl ether compound (c) is selected from trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, and pentaerythritol tetraglycidyl ether. A linear polyacetal resin (A) is obtained by copolymerizing 99.9 to 95.0% by weight of trioxane (a) with 0.1 to 5.0% by weight of a compound (b) selected from a monofunctional cyclic ether compound and a monofunctional cyclic formal compound. The disk guide component according to claim 1, wherein The melt index (MI _A ) of the linear polyacetal resin (A) is 1 to 50 g / min, the melt index (MI _B ) of the branched or cross-linked polyacetal resin ( _B ) is 0.1 to 10 g / min, The linear polyacetal resin (A) and the branched or cross-linked polyacetal resin (B) are selected so that the ratio (MI _B / MI _A ) satisfies 0.02 to 1.5. Disc guide parts as described in The disk guide component according to any one of claims 1 to 7, wherein the disk drive device is for vehicle use.

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