JP2504957C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transparent substrate, and particularly to a thin optical transparent substrate, such as an optical disk substrate, having a large projected area showing a good appearance by injection molding and exhibiting a good appearance. About. [Prior art and its problems] There are various known molding methods for producing an optical transparent substrate using a transparent thermoplastic resin. In particular, the injection molding method is the most industrially used means in terms of productivity, that is, molding of a large number of products at a high production rate. By the way, when the product has a large projected area and a small thickness, such as an optical disc substrate, which is one type of optical transparent substrate, the production by injection molding is described in detail below. It is very difficult to do. That is, many of transparent thermoplastic resins such as polymethyl methacrylate (PMMA), polycarbonate (PO), and poly (4-methylpentene 1) (PMP) have high viscosity, and therefore, during injection molding, the resin temperature is raised to lower the viscosity and the flow is reduced. You have to improve your sex. However, even if the projection area is large, the resin having a small thickness has a small amount of resin, so that the residence time of the resin in the injection molding machine becomes long. Further, since the steel sheet passes through a thin portion at a high speed in the mold, mechanical shear insulation is likely to occur. In this way, the resin that stays for a long time under high temperature by external heating and also experiences internal heating such as shear heat insulation is naturally decomposed and deteriorated, weakening the mechanical strength of the obtained product and mixing in burns This causes a problem that the optical disc substrate cannot be used as a result. Another problem is the fact that microvoids are often generated in manufactured disk substrates. This phenomenon can be considered to be true of injection molding in general, but the means of pre-drying the material resin and venting the mold, which are conventionally considered to be effective for solving this kind of problem, are not suitable for the low flow resin described above. However, the production of a disk substrate by high-temperature injection molding using the method is insufficient. Another problem is that pit portions and guide grooves of the disk are not accurately transferred to the disk substrate. Yet another problem is that a phenomenon called flash occurs on or in the disk substrate. Here because the flash is a phenomenon resulting in fogging of the irregular shape in the radial direction of the disk, which is completely different phenomenon from the shea Le bar streak showing a relatively clear streak-like shape. Such a phenomenon may not be so problematic in ordinary molded articles, but it should never be used in applications such as transparent substrates. This phenomenon often occurs, for example, even if sufficient time is taken for pre-drying the material resin, which is said to be effective for preventing ordinary silver streaks, and causes headaches among those skilled in the art. Still another problem is that the transparent substrate obtained by molding is colored yellow. [INVENTION Problems to be Solved] The present inventors have found that mow view of the current situation either be injection molded like a thin e.g. optical disk substrate transparent substrate especially projected area for optics having large thickness, mechanical No deterioration of the mechanical properties, no generation of voids, good transferability of the bit or guide groove, and furthermore, the inventors arrived at the present invention as a result of repeatedly examining whether a product having no flash and no coloring could be obtained. It is. [Means for Solving the Problems] That is, the present invention relates to a ring-opened polymer of tetracyclododecenes and norbornene.
Hydrogenated ring-opening copolymers of olefins or copolymers of cyclic olefins with ethylene
A transparent thermoplastic resin obtained by blending two or more phenolic antioxidants having a β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl group with a transparent thermoplastic resin selected from the coalesced resins. Is a transparent substrate for optical use. [Operation] The transparent thermoplastic resin, those that have been hydrogenated ring-opening copolymer alone opening polymer or Norubo Le nen such Tetorashikurodo decene, such as shown in JP 60-26024, also Separately, copolymers of ethylene with cyclic olefins such as norbornene, tetracyclododecene, methyltetracyclododecene (for example,
168708, 61-115912, 61-115916, 61-120
816) is used. The transparent thermoplastic resin as described above has a high Tg , and the resin temperature on the resin surface that comes into contact with the mold when flowing into the mold by injection molding decreases, and the surface solidifies relatively quickly. For this reason, it is presumed that volatile components and the like, which are presumed to be based on the oxidative deterioration of the resin, are trapped inside the resin and cause the flash described above. That is, Tg
The higher the value, the faster the surface solidifies and the flash becomes remarkable. Therefore, when the present invention is applied to such a resin, the flash is prevented and useful. Therefore, the resin preferably used is a copolymer of ethylene and a cyclic olefin. A phenolic antioxidant having a β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl group is incorporated into a transparent thermoplastic resin to provide an appearance sufficient to be used as an optical material. That void, shea Le bar streak, to reduce flash, hue stabilized. Of course, the transferability of bits is also improved, so that it is particularly suitable for optical disk substrate applications. Examples of such a phenolic antioxidant include tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane and β- (
3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid alkyl ester or 2,2'-oxamidobis [ethyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Can be exemplified. As the β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid alkyl ester, an alkyl ester having 18 or less carbon atoms is particularly preferable. In the present invention, the object can be achieved by using two or more of the above specific phenolic antioxidants. If only one kind is used or if only other antioxidants are used, the object of the present invention cannot be achieved. It is not clear why the structure of the present invention provides excellent hue without flash or the like, but according to the present inventors' estimation, the phenolic antioxidant having the structure used in the present invention is high. shows the plasticizer effects to transparent thermoplastic resin Tg, low at least the apparent Tg of the near surface of the resin is lowered, the volatile component of the resin surface in contact with the mold (resin degradation, thus generated deteriorates It is also considered that one of the causes is that the boiling point material and trace amount of monomer originally contained in the resin are easily escaped from the surface. For this reason, in the present invention, a relatively low molecular weight, ie, 60
Phenolic antioxidants having a molecular weight of 0 or less are particularly preferred. The mixing ratio of the phenolic antioxidant to the transparent thermoplastic resin is 100
The amount is 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, more preferably 0.1 to 1 part by weight with respect to parts by weight. In addition, the range of the compounding amount of the above-mentioned compound is that if the compounding amount is too large, the initial physical properties as a transparent substrate cannot be stably maintained for a long period of time, or if the amount is too small, the effects intended by the present invention are hardly exhibited. It was set because it was not effective enough to endure practically even if it appeared. In the resin composition of the present invention, when a transparent resin produced using a halogen-containing catalyst such as a Ziegler catalyst is used, the halogen contained in the remaining catalyst residue does not damage the molding machine, A halogen scavenger should be used in combination. When the present invention is described using an optical disk substrate as an example, first, a resin and the above compound,
If necessary, an amount of another stabilizer which does not impair the effect of the present invention is mixed with a ribbon blender, a tumbler blender, a Henschel mixer, or the like, and then melt-mixed with an extruder, a Banbury mixer, a two-roll mixer, or carbonized. Dissolve in hydrogen or aromatic solvent and mix into the polymer solution, then single screw extruder, vented extruder, twin screw extruder, three screw extruder, conical twin screw extruder, co-kneader, platyfi Caters, mixers, twin screw conical screw extruders,
Injection molding is performed using a planetary screw extruder, gear type extruder, screwless extruder, etc., and a disk molding die (including a set of information bits and a stern bar for forming guide grooves) Molding. As the gate used in the injection molding, various known gates may be used, but from the viewpoint of shrinkage and warpage, a center pin gate or a center disk gate, preferably a gate diameter of 3 mm or less, particularly 0.5 to 2.5. It is preferable to use a center pin gate having a thickness of 0 mm and a gate thickness of 1 mm or less, particularly a center disk gate having a thickness of 0.2 to 0.8 mm. The disk substrate obtained by injection molding is completed by forming a recording layer or a metal layer for reflecting a laser beam by a known method such as a vapor deposition method or a sputtering method, and further providing a protective layer as necessary. . EXAMPLES Hereinafter, the content of the present invention will be described with preferred examples, but the present invention is not limited to these examples unless otherwise specified. Example 1 Melt flow rate under a load of 2.15 kg and a temperature of 260 ° C. (MFR: ASTM D 1238)
) Was added to an ethylene / tetracyclododecene copolymer (ethylene content 60 mol%) having a weight of 35 kg / 10 min and tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane ( A), n-octadecyl-β- (3,5-di-ter
After blending t-butyl-4-hydroxyphenyl) propionate (B) and zinc stearate (C) with a Henschel mixer, pellets are formed at a temperature of 230 ° C. using a twin screw extruder having a screw diameter of 40 mm. did. Using these pellets as raw materials, a Sumitomo Heavy Industries P40 / 25A injection molding machine and a center disk gate mold (a mold set with a stan bar for forming information pits)
Was used to form a disk substrate having a diameter of 80 mm and a thickness of 1.0 mm at a temperature of 280 ° C., and the items shown in Table 1 were evaluated. In addition, these items were evaluated visually, and the evaluation criterion was 1-5 bad. The compounding amount of the stabilizer indicates parts by weight based on 100 parts by weight of the resin material. Example 2 Instead of (B) 2,2'-oxamidobis [ethyl-3- (3,5-di-tert-butyl-4-
[Hydroxyphenyl) propionate] (D) except that (D) was used. Table 1 shows the results. Example 3 Example 3 was repeated, except that (D) was used instead of (A). Table 1 shows the results
Shown in Comparative Example 1 Example 1 was repeated except that the amount of (A) was increased without using (B).
The same was done. Table 1 shows the results. Comparative Example 2 Example 1 was repeated except that the amount of (B) was increased without using (A) in Example 1.
The same was done. Table 1 shows the results. Comparative Example 3 Example 2 was repeated except that the amount of (D) was increased without using (A) in Example 2.
The same was done. Table 1 shows the results. Comparative Example 4 In Example 1, instead of (B), 1,3,5-trimethyl-2,4,6-tris (3,5-di-
The procedure was performed in the same manner as in Example 1 except that tert-butyl-4-hydroxybenzyl) benzene (E) was used. Table 1 shows the results. Comparative Example 5 The same procedure was performed as in Example 1 except that 3,5-di-tert-butyl-4-hydroxytoluene (F) was used instead of (B). Table 1 shows the results. [Effects of the Invention] According to the present invention, mechanical properties are excellent, no voids are generated, no flash is generated, there is no coloring, and transferability of a stamper pattern in a mold, for example, a bit portion of a disk or a guide is provided. An excellent effect that grooves can be transferred accurately is exhibited. Therefore, the optical disk substrate, the large-sized display substrate, the transparent electrode substrate, the transparent electric circuit substrate, the VD work CRT cover, and the like can be suitably used for manufacturing a thin optical transparent substrate product having a large projection area but a small thickness.

Claims (1)

Claim (3) (Japanese Patent No. 2504957 [Claims]
] Is deleted, and in order to correspond to this, "page 6 of the specification, page 2, right column, line 7 of the same specification" Is
Transparent thermoplastic resins selected from hydrogenated ring-opening copolymers of tetracyclododecenes or ring-opening copolymers with norbornenes, or copolymers of cyclic olefins and ethylene, '' Page 6, lines 8 to 9 (page 2, right column, lines 12 to 13) "The transparent thermoplastic resin is polystyrene (PS) or PMMA, PC, or PMP in addition to the aforementioned PMMA." Of "as a transparent thermoplastic resin,"
Page 6, lines 16 to 20 (page 19, right column, lines 19 to 24) "In the present invention which can exemplify the like, it is 120 ° C. or higher. That is, those having a high Tg""A transparent thermoplastic resin as described above is used. The transparent thermoplastic resin has a high Tg," and for the purpose of correcting errors and clarifying unclear statements, Page 5, line 2 (page 38, left column, line 38), page 7, line 15 (page 2, right column, line 38) "Silyburst leak" Page 13, line 13 (page 49, left column, line 49), "Karu Current State" is referred to as "the current state", page 6, lines 10-11 (the same specification, line 2). Page right column, line 14) "Tetracyclodotecene" means "tetracyclododecene"
Pp. 6, line 11 (page 2, right column, line 15), “norbornene” is referred to as “norbornene”, and page 7, line 6 (page 2, right column, line 29 in the specification). Line) "The surface is solidified" means "the surface is solidified" and page 9 line 1 and line 2 (the same document, page 3 left column line 11) "deterioration" Corrected "by degradation." (54) [Title of the Invention] Transparent substrate for optics [Claims] (1) Ring-opening polymer of tetracyclododecenes alone or ring-opening copolymer with norbornenes
Selected from hydrogenated coalesced copolymers or copolymers of cyclic olefins and ethylene
Characterized in that the transparent thermoplastic resin comprises two or more phenolic antioxidants having a β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl group. Optical transparent substrate. (2) tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid alkyl ester and 2 , 2'-Oxamidobis [ethyl-3- (3,5-di-ter
t-butyl-4-hydroxyphenyl) propionate]
The optical transparent substrate according to claim 1, wherein a seed is blended. (3) The optical transparent substrate according to claim 1 or 2, wherein the optical transparent substrate has a large projected area and a small thickness. (4) The optically transparent substrate is an optical disk substrate.
Item 14. The optical transparent substrate according to any one of the above items. (5) The optical transparent substrate according to any one of claims 1 to 4, which is manufactured by injection molding.