JPH0724120B2 - Manufacturing method of information recording board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an information recording substrate having an air soldering structure in which a spacer and a disk substrate are bonded by ultrasonic welding, and particularly, heat resistance, The present invention relates to a method for manufacturing an information recording substrate having an air-sun-germany structure, which has excellent water resistance and chemical resistance, a very low water absorption rate, and a small birefringence.

[Conventional technology]

Information recording substrate (hereinafter also referred to as an optical disc) In particular, as a write-once type information recording substrate, two disc substrates 1 and 2 having recording layers are made to face each other,
In addition, a structure in which an outer peripheral spacer 3 and an inner peripheral spacer 4 are interposed and bonded so as to form a space therebetween, that is, a so-called air-sintered structure is already known.

As a material forming such an optical disk, a transparent material, especially a material which has been used or studied as an information recording substrate of another type in the related art, can be applied. That is,
Specifically, polymethyl methacrylate, polycarbonate, polystyrene, hard polyvinyl chloride, epoxy resin, glass and the like are used.

[Problems of conventional technology]

However, each of the above materials also has advantages and disadvantages, and thus even if an optical disc is manufactured using these materials, the obtained optical disc reflects the advantages and disadvantages of the material. .

That is, polymethylmethacrylate has a thermal denaturation temperature of 10
It has poor heat resistance at around 0 ° C, and has a high water absorption rate of 0.4%, which causes dimensional changes due to moisture absorption and warpage is likely to occur. Although polycarbonate has excellent heat resistance, it has a large photoelastic constant and a large birefringence. Moreover, it has a low surface hardness and is easily scratched, and has a water absorption rate of 0.15%, which is smaller than that of polymethyl methacrylate, but the problem of moisture resistance still remains. Polystyrene is inferior in heat resistance, impact resistance, and surface hardness, and since interference fringes are generated after molding and birefringence is large, polystyrene cannot be practically used as an optical disk. Polyvinyl chloride is also very poor in heat resistance and has poor workability and durability, so that it is difficult to use it as an optical disc. Epoxy resin is very excellent in heat resistance, but has poor moldability and has a problem in mass production. Moreover, the photoelastic constant is large, and there is a problem of birefringence due to residual stress during molding. Although glass is excellent in heat resistance, moisture resistance, surface hardness, etc., it is brittle and easily broken, and is heavy, so that it is inferior in handleability and productivity.

As described above, the conventionally known materials have advantages and disadvantages when applied to the optical disk having the air-sanding structure, which is a target of the manufacturing method of the present invention, and a material having perfectly balanced performance is obtained. It's hard to be beaten.

Furthermore, in order to manufacture optical discs by laminating disc substrates, they are adhered with a thermosetting or UV-curing contact agent, but the monomer components in the adhesive and by-products during curing are recorded on the recording layer. There is a possibility that the recording layer may be adversely affected, or an excessive amount of the adhesive may squeeze out and adversely affect the recording layer. Therefore, a new bonding technique that does not use an adhesive is required, and ultrasonic welding can be considered as an example. However, most of the conventionally known materials described above have a large photoelastic constant, and there is a problem that residual stress caused by welding is damaged and the secondary refraction becomes large, so that the material cannot be used as an optical disk.

[Problems to be solved by the invention]

An object of the present invention is to provide a method of manufacturing an information recording substrate that does not use an adhesive. Another object of the present invention is to provide a method of manufacturing an information recording substrate which does not increase birefringence even if ultrasonic welding is performed. Still another object of the present invention is to provide a manufacturing method capable of manufacturing an information recording substrate having excellent heat resistance, chemical resistance and moisture resistance.

[Means for solving problems]

That is, the present invention provides a method for manufacturing an information recording substrate having an air soldering structure by ultrasonically welding two disc substrates through an outer peripheral spacer and an inner peripheral spacer,
The polymer constituting the spacer and the disk substrate is a copolymer of the monomer component represented by the formula (1) and ethylene, and the monomer component represented by the formula (1) in the polymer is represented by the formula: A method for producing an information recording substrate is characterized by using a polymer having a structure shown in (2).

(In the formula, R ^{1 to} R ¹² are hydrogen or an alkyl group and may be the same or different, and R ⁹ or R ¹⁰ and R ¹¹ or R ¹² may form a ring with each other. Is 0 or 1.) [Operation] In the production method of the present invention, in the polymer constituting the disk substrate and the spacer, the monomer component represented by the above formula (1) has a structure mainly represented by the formula (2). It is a copolymer with ethylene. Especially ethylene / formula (1)
The molar ratio of the monomer components of 5/95 to 95/5, especially 40/60 to 9
The range of 0/10 is preferable, and α-olefins other than ethylene, chain dienes, cyclic olefins other than the formula (1) and the like may coexist, and in this case, the total amount of these monomers / the formula (1) The molar ratio of the monomer components of 5 / 95-95
/ 5, particularly preferably 30/70 to 90/10. Further, in the present invention, the monomer component of the formula (1) is not only a single component,
It goes without saying that a plurality of components represented by the formula (1) may be mixed.

Specific examples of the monomer component represented by the formula (1) include the following, but the examples shown here are extremely limited and are represented by the formula (1). Anything can be the monomer component of the present invention.

Of these, n = 1 in formula (1), that is, formula (3), The monomer component represented by is preferable in terms of availability of the monomer or easy synthesis of the monomer.

To prepare the above-mentioned monomer components, for example, US Patent
3557072 (JP-B-46-14910) and JP-A-57-
The method of Japanese Patent No. 154133 can be applied.

The α-olefin which can be copolymerized with the monomer component of the formula (1) and ethylene includes 3 to 20 carbon atoms,
Suitably 3 to 10 α-olefins such as propylene, 1-butene, 3-methyl-1-butene, 1-
Pentene, 3-methyl-1-pentene, 4-methyl-1
Examples include-pentene, 1-hexane, 1-octane, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-icosene.

Cyclic olefins other than formula (1), which is another component that can be copolymerized, include cycloolefins and styrenes having no bridge, and examples thereof include cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, and Examples thereof include-(2-methylbutyl) -1-cyclohexene, styrene and α-methylstyrene. Dicyclopentadiene, ethylidene norbornene,
Vinyl norbornene and polyene are also copolymerizable. Unsaturated carboxylic acids such as (anhydrous) maleic acid can also be copolymerized.

In addition to the monomer components described above, other copolymerizable monomer components may be contained in the polymer in a small amount within the range not impairing the object of the present invention.

The polymer is produced by polymerizing using a well-known Ziegler catalyst and vanadium-based Ziegler catalyst. More specifically, it is disclosed in a prior patent application filed by the applicant (for example, JP-A-60-168708). A characteristic of the polymer is that the monomer component of the formula (1) mainly has a structure represented by the formula (2) in the polymer,
As a result, the iodine value of the polymer is usually 5 or less, and most is 1 or less. Moreover, ¹³ C-NMR confirms that this structure is adopted.

According to the manufacturing method of the present invention, the disk substrates 1 and 2 made of the above-mentioned polymer are bonded via the outer peripheral spacer 3 and the inner peripheral spacer 4 so that their recording layers face each other, and the spacer and the disk are joined. The joint surface with the substrate is welded by ultrasonic waves. The information recording substrate thus obtained is
Due to the existence of the spacer, a space exists between the two disk substrates. Moreover, when the polymer to be ultrasonically welded is the above-mentioned polymer, the photoelastic sensitivity and the photoelastic constant are small, so that the deterioration of the birefringence due to the welding is small and the deterioration of the practical optical characteristics due to the bonding can be almost ignored.

〔The invention's effect〕

According to the present invention, since there is no change in optical characteristics due to ultrasonic welding and it has excellent heat resistance, it can be used at or near high temperature parts, and it has excellent chemical resistance and solvent resistance, so it is easy to handle. Since it has excellent water resistance, it does not need to be waterproofed. It is possible to manufacture an information recording substrate with an Air-San German structure having excellent characteristics, and since no adhesive is used, by-products that damage the recording layer are generated. Since it can be welded instantly without any defects, it has the characteristic that it has excellent continuous productivity.

〔Example〕

The contents of the present invention will be described below with reference to preferred examples, but the present invention is not limited to these examples unless otherwise specified.

Example 1 Ethylene / tetracyclododecene copolymer (ethylene content 60 mol%, tetracyclododecene In the polymer as determined by ¹³ C-NMR It was confirmed that the following structure was adopted) as a raw material, and two disk substrates having a diameter of 130 cm and a thickness of 1.2 mm were injection molded. The obtained disk substrate had no warp or distortion, was transparent, and had no dimensional shrinkage, and its birefringence was measured and found to be a value equivalent to that of polymethylmethacrylate.

An ethylene / tetracyclododecene copolymer (ethylene content 67.8 mol%) is used to form an outer diameter spacer with an outer diameter of 130 mm, an inner diameter of 125 mm, and a thickness of approximately 0.4 mm, and an outer diameter of 36 mm, an inner diameter of 15 mm, and a thickness of approximately
An inner peripheral spacer of 0.4 mm was injection molded.

Next, an information recording substrate having an air soldering structure was manufactured as follows using these disk substrates and spacers.

That is, the outer peripheral spacer and one disk substrate are ultrasonically welded together, and then the welded disk substrate of the outer peripheral spacer and the remaining one disk substrate are joined together via the inner peripheral spacer to collectively bond the inner peripheral spacer joint portion. After ultrasonic welding, the remaining outer peripheral spacer and one disk substrate unwelded joint were ultrasonically welded. The condition for ultrasonic welding is about 0 output.
8kw, oscillation time 0.05 seconds, and presser foot pressure 0.7kg / cm ² .

In the information recording substrate thus manufactured, the welded portions were evenly welded, and the substrate was not distorted due to the influence of welding. Further, the birefringence after welding was the same as that of the raw disk substrate, and no influence on the birefringence due to welding was observed. Further, the welding strength was sufficient.

Example 2 The same procedure as in Example 1 was carried out except that the ethylene content of the ethylene / tetracyclododecene copolymer, which was the material for the spacer, was changed to 76.7 mol%. The results were exactly the same as in Example 1.

[Brief description of drawings]

 FIG. 1 is a sectional view showing an information recording substrate of the present invention.

Claims (3)

[Claims] 1. A method for producing an information recording substrate having an air sandwich structure by ultrasonically welding two disc substrates through an outer peripheral spacer and an inner peripheral spacer, wherein a polymer constituting the spacer and the disc substrate comprises: A polymer which is a copolymer of a monomer component represented by the formula (1) and ethylene, and in which the monomer component represented by the formula (1) has a structure represented by the formula (2). A method for manufacturing an information recording substrate characterized by being used. (In the formula, R ^{1 to} R ¹² are hydrogen or an alkyl group and may be the same or different, and R ⁹ or R ¹⁰ and R ¹¹ or R ¹² may form a ring with each other. It is 0 or 1.) 2. In the formulas (1) and (2), n is 1
The method for producing an information recording substrate according to claim 1, wherein 3. In the formulas (1) and (2), R ^{1 to} R
The method for producing an information recording substrate according to claim 1 or 2, wherein ¹² is hydrogen or an alkyl group having 1 to 4 carbon atoms.