JPH04253765A - Resin composition and substrate for optical recording medium - Google Patents

Abstract

PURPOSE:To provide a useful optical material improved in releasability in molding substrates by incorporating a full ester of pentaerythritol with a specific saturated higher fatty acid and phosphor acid in an aromatic polycarbonate resin. CONSTITUTION:An aromatic polycarbonate resin is obtained by reacting, for instance, 2,2-bis(4-hydroxyphenyl)propane with phosgene. Then, the polycarbonate resin is mixed with 0.01-0.3wt.% of a full ester of pentaerythritol, preferably pentaerythritol tetrastearate or pentaerythritol tetrabehenate, with a 12-22C saturated higher fatty acid and 0.0005-0.01wt.% of phosphorous acid to obtain a resin composition, which is molded to obtain a substrate for an optical recording medium.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition useful as an optical material, and a substrate for an optical recording medium comprising the resin composition.

0002

[Prior Art] Recently, polycarbonate resin has come to be widely used as a substrate material for lenses, optical information disks, etc., taking advantage of its characteristics such as transparency, heat resistance, and dimensional stability. Improvements in stability, hydrolysis resistance and mold release properties have become important issues.

Conventionally, organic phosphites have been the main stabilizers for polycarbonate resins in practice, but it is well known that hydrolysates of these organic phosphites accelerate the decomposition of the polycarbonate resin itself. Also,
When polycarbonate resin is hydrolyzed, the decomposed products precipitate into the molded product as fine white spots, blocking the passage of light rays.

[0004] Phosphonite-based compounds that have been proposed other than organic phosphites also have similar hydrolyzability. Furthermore, organic phosphines and organic phosphine oxides have the disadvantage of insufficient improvement in heat resistance stability, which results in marked yellowing of molded articles when heated.

On the other hand, among optical molded products, especially optical discs,
Lenses and other products are manufactured by injection molding, but when releasing from a mold, a large release resistance can cause warping of the molded product and optical distortion, so it is necessary to use a mold release agent. . In particular, in the case of optical discs, it is necessary to accurately transfer the irregularities of 1 μm or less on the stamper, and this is largely dependent on the performance of the mold release agent.

Conventionally, paraffin, silicone oil, fatty acids, fatty acid esters, fatty acid partial esters (particularly fatty acid monoglycerides), and the like have been known as mold release agents for polycarbonate resins. Among these, fatty acids and fatty acid monoglycerides have excellent mold release properties when used in small amounts, but when polycarbonate resins containing these mold release agents are left in high temperature and high humidity conditions (80°C/90% RH), , promotes the hydrolysis of polycarbonate resin, but from the viewpoint of mold releasability, it is necessary to add, for example, about 0.04% by weight.

Furthermore, as shown in Japanese Patent Publication No. 55-24468 and Japanese Patent Publication No. 61-41939, by using a full ester of a polyhydric alcohol and a higher saturated fatty acid as a mold release agent, fatty acid moieties can be Attempts have been made to avoid the accelerated hydrolysis of polycarbonate resins under high temperature and humidity conditions, which occurs when esters are used. However, at present, it cannot be said that even such methods provide sufficient measures against the hydrolysis of polycarbonate resins.

[0008]

[Problems to be Solved by the Invention] The present invention has been made in order to solve the problems of the prior art.
A polycarbonate for optical molding materials that can provide substrates for optical recording media that have excellent moldability, especially mold release properties during substrate molding, have low corrosion resistance of recording films under high temperature and high humidity conditions, and have excellent hydrolysis resistance. The object of the present invention is to provide a resin composition and a substrate for an optical recording medium made of the resin composition.

[0009]

[Means for Solving the Problems] That is, the present invention is characterized in that an aromatic polycarbonate resin contains a full ester of pentaerythritol and a higher saturated fatty acid having 12 to 22 carbon atoms and phosphorous acid. and a substrate for an optical recording medium comprising the resin composition.

The present invention will be explained in detail below. The resin composition of the present invention is made by containing an aromatic polycarbonate resin, a full ester of pentaerythritol and a specific higher saturated fatty acid having 12 to 22 carbon atoms, and phosphorous acid.

[0011] The aromatic polycarbonate resin is not particularly limited and a wide range of resins can be used. For example, 2,2-bis(4-hydroxyphenyl)
Examples include those obtained by the reaction of propane and phosgene.

Further, as the full ester of pentaerythritol and a higher saturated fatty acid, a full ester of a higher saturated fatty acid having 12 to 22 carbon atoms, preferably 14 to 22 carbon atoms, and pentaerythritol is used, such as pentaerythritol tetra. Myristate, pentaerythritol tetrapalmitate, etc., particularly preferably pentaerythritol tetrastearate and pentaerythritol tetrabehenate are used. Moreover, one type or two or more types of the above-mentioned full esters can be used. In esters with pentaerythritol using higher saturated fatty acids with a carbon number outside the range of 12 to 22,
Mold releasability, low corrosion of recording film under high temperature and high humidity,
and hydrolysis resistance cannot be satisfied at the same time, which is undesirable.

The content of the full ester of petaerythritol and higher saturated fatty acid contained in the resin composition of the present invention is preferably 0.01 to 0.3 wt%,
Particularly preferably 0.05 to 0.2 wt%. If it is less than 0.01 wt%, the mold releasability will deteriorate, and if it is less than 0.3 wt%
Above this level, the corrosion resistance and hydrolysis resistance of the recording film at high temperatures and high humidity deteriorate, which is not preferable.

[0014] Furthermore, the content of phosphorous acid contained in the resin composition of the present invention is 0.0005 to 0.01w.
t%, particularly preferably 0.001 to 0.005 wt%. If it is less than 0.0005 wt%, the hydrolysis resistance will be poor, and if it is more than 0.3 wt%, the corrosion resistance of the recording film at high temperature and high humidity will be poor, which is not preferable.

Next, a substrate for an optical recording medium can be manufactured using the above resin composition by a conventional method, for example, by injection molding, extrusion molding, or the like.

[0016]

[Function] The resin composition of the present invention comprises an aromatic polycarbonate resin, pentaerythritol and a specific carbon number of 12 to
Contains full ester of 22 higher saturated fatty acids and phosphorous acid, so it has excellent mold releasability and good moldability when producing substrates for optical recording media, and is also suitable for optical recording under high temperature and high humidity conditions. The corrosion resistance of the recording film formed on the medium substrate is low, and the hydrolysis resistance of the optical recording medium substrate can be satisfied at the same time.

[0017]

[Examples] The present invention will be specifically explained below with reference to Examples. Example 1 A homopolymer of 2,2-bis(4-hydroxyphenyl)propane prepared by reacting 2,2-bis(4-hydroxyphenyl)propane with phosgene (viscosity average Molecular weight: 180
00), pentaerythritol tetrastearate (
PTS) 0.10wt% and phosphorous acid 0.003wt
% was molded using an ordinary injection molding machine to obtain a substrate for an optical recording medium having a thickness of 1.2 mm. The obtained substrate was coated with SiN/GdFeCo/TbFeCo
/SiN layers were sequentially stacked to form a magneto-optical film. Each film thickness is 900 Å/300 Å/500
It was Å/600 Å.

A polycarbonate substrate having a thickness of 1.2 mm was adhered thereon using a hot melt adhesive (HM) to obtain an optical recording medium having the following layer structure. Table 1 shows the evaluation results of the mold release properties, adverse effects on the recording film, and hydrolysis properties of the prepared substrates. PC/SiN/GdFeCo
/TbFeCo/SiN/HM/PC

Example 2 Pentaerythritol tetrastearate (PTS) 0
．． A substrate was prepared in the same manner as in Example 1, except that 0.10 wt% of pentaerythritol tetrabehenate (PTB) was used instead of 10 wt%, and an optical recording medium was obtained. The evaluation results are shown in Table 1.

Examples 3, 4 and 5 The content of pentaerythritol tetrastearate (PTS) was 0.03wt%, 0.05wt%, 0.15w
A substrate was prepared in the same manner as in Example 1 except that the amount was changed to t%, and an optical recording medium was obtained. The evaluation results are shown in Table 1.

Examples 6, 7 and 8 The content of phosphorous acid was 0.001 wt%, 0.005 wt%
% and 0.007wt%, a substrate was prepared in the same manner as in Example 1, and an optical recording medium was obtained. The evaluation results are shown in Table 1.

Example 9 Pentaerythritol tetrastearate (PTS) 0
．． A substrate was prepared in the same manner as in Example 1, except that 0.10 wt % of pentaerythritol tetramyristate (PTM) was used instead of 10 wt %, and an optical recording medium was obtained. The evaluation results are shown in Table 1.

Examples 10, 11 and 12 The content of pentaerythritol tetrabehenate (PTB) was 0.0.
A substrate was prepared in the same manner as in Example 2 except that the concentrations were 3wt%, 0.05wt%, and 0.15wt%, and an optical recording medium was obtained. The evaluation results are shown in Table 1.

Examples 13, 14 and 15 The content of phosphorous acid was 0.001 wt%, 0.005 wt%, 0.00
A substrate was created in the same manner as in Example 2 except that the content was 7wt%,
An optical recording medium was obtained. The evaluation results are shown in Table 1.

Comparative Example 1 A substrate was prepared in the same manner as in Example 1 except that it did not contain phosphorous acid, and an optical recording medium was obtained. Table 2 shows the evaluation results.
Shown below.

Comparative Example 2 A substrate was prepared in the same manner as in Example 1 except that pentaerythritol tetrastearate (PTS) was not contained, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 3 A substrate was prepared in the same manner as in Example 1, except that the content of pentaerythritol tetrastearate (PTS) was 0.3 wt%, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 4 A substrate was prepared in the same manner as in Example 1 except that the content of phosphorous acid was 0.01 wt%, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 5 Pentaerythritol tetrastearate (PTS) 0
．． Stearic acid monoglyceride (instead of 10wt%)
A substrate was prepared in the same manner as in Example 1, except that 0.05 wt% of SMG) was used, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 6 Pentaerythritol tetrastearate (PTS) 0
．． A substrate was prepared in the same manner as in Example 1, except that 0.05 wt% of pentaerythritol tetrastearate (PTS) and 0.01 wt% of stearic acid monoglyceride (SMG) were used instead of 10 wt%, and an optical recording medium was obtained. . The evaluation results are shown in Table 2.

Comparative Example 7 A substrate was prepared in the same manner as in Example 1 except that 0.003 wt % of organic phosphite was used instead of 0.003 wt % of phosphorous acid, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 8 A substrate was prepared in the same manner as in Example 1, except that the content of pentaerythritol tetrabehenate (PTB) was 0.3 wt%, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 9 Pentaerythritol tetrastearate (PTS) 0
．． A substrate was prepared in the same manner as in Example 1, except that pentaerythritol tetraoctanate (PTO) was used instead of 10 wt%, and an optical recording medium was obtained. Table 2 shows the evaluation results.
Shown below.

Comparative Example 10 Pentaerythritol tetrastearate (PTS) 0
．． Pentaerythritol tetralignocerate (Pentaerythritoltet) instead of 10wt%
A substrate was prepared in the same manner as in Example 1 except that Ralignocerate (PTL) was used, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 11 Pentaerythritol tristearate (PTriS) 0.1 instead of 0.10 wt% pentaerythritol tetrastearate (PTS)
A substrate was prepared in the same manner as in Example 1 except that 0 wt% was used, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Comparative Example 12 Pentaerythritol tetrastearate (PTS) 0
．． Instead of 10wt%, 0.05wt% of pentaerythritol tetrastearate (PTS) and 0.05wt of pentaerythritol tristearate (PTriS).
A substrate was prepared in the same manner as in Example 1 except that % was used, and an optical recording medium was obtained. The evaluation results are shown in Table 2.

Test method: Mold releasability: Evaluation was made based on the magnitude of mold release defects visually observed on the molded substrate and the mold release resistance. ◎: Mold release resistance 260Kg or less, mold release failure cannot be confirmed (visually, microscope) ○: Mold release resistance 260Kg to 290Kg, mold release failure cannot be confirmed (visually, microscope) △: Mold release resistance 290Kg to 350Kg, under microscope Poor mold release can be confirmed ×: Mold release resistance is 350 kg or more, mold release defects can be visually confirmed.

Effect on recording film: After a magneto-optical recording film was formed on a molded substrate, it was left in a high temperature, high humidity (70° C., 90% RH) atmosphere for 1000 hours, and the corrosion of the recording film was evaluated based on the degree of corrosion. ◎: There is no corrosion of 10 μm or more on the recording film. ○: There are several pieces of corrosion of 10 μm to 100 μm on the recording film. △: There are several dozen pieces of corrosion of 10 μm to 100 μm on the recording film. ×
: Recording film has corrosion of 100 μm or more in several pieces.

003
9] Hydrolysis resistance: After forming a magneto-optical recording film on a molded substrate,
Evaluation was made based on the size of the hydrolyzed portion of the molded substrate after being left in a high temperature, high humidity (70° C., 90% RH) atmosphere for 1000 hours. ◎: No hydrolyzed portions of 10 μm or more on the molded substrate ○: Several hydrolyzed portions of 10 μm to 100 μm on the molded substrate △: Several dozen hydrolyzed portions of 10 μm to 100 μm on the molded substrate ×: Hydrolysis of the molded substrate There are several parts with a diameter of 100 μm or more.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Effects of the Invention] As explained above, according to the present invention,
By using a resin composition in which an aromatic polycarbonate resin contains a full ester of pentaerythritol and a higher saturated fatty acid having 12 to 22 carbon atoms and phosphorous acid, it has excellent mold releasability during substrate molding, and It is possible to obtain a substrate for an optical recording medium whose recording film is less corrosive under high temperature and high humidity conditions and has excellent hydrolysis resistance. The resin composition of the present invention is useful as an optical material.

Claims (5)

[Claims] 1. A resin composition comprising an aromatic polycarbonate resin containing a full ester of pentaerythritol and a higher saturated fatty acid having 12 to 22 carbon atoms and phosphorous acid. [Claim 2] The pentaerythritol and carbon number 1
The content of full esters of higher saturated fatty acids of 2 to 22 is 0.
．． The resin composition according to claim 1, wherein the amount is 01 to 0.3 wt%. Claim 3: The content of the phosphorous acid is 0.0005.
The resin composition according to claim 1, wherein the amount is 0.01 wt%. 4. The pentaerythritol and carbon number 1
2. The resin composition according to claim 1, wherein the full ester with 2 to 22 higher saturated fatty acids is pentaerythritol tetrastearate or pentaerythritol tetrabehenate. 5. An optical recording medium comprising a resin composition comprising an aromatic polycarbonate resin containing a full ester of pentaerythritol and a higher saturated fatty acid having 12 to 22 carbon atoms and phosphorous acid. substrate.