JPH02253201A - Optical molded product - Google Patents

Abstract

PURPOSE:To obtain an optical molded product having superior transparency, heat resistance, small optical strain and a low rate of water absorption and hardly causing warpage due to water absorption by using specified polyester resin. CONSTITUTION:Polyester resin having repeating units represented by formula I as the principal chain and 10,000-100,000 number average mol. wt. is used to obtain an optical molded product, e.g., the substrate of an optical recording medium such as an optical disk or card or an optical element such as a lens, a prism or a diffraction grating. In the formula I, A is preferably 2-20C, especially 2-10C divalent satd. aliphatic hydrocarbon group or 3-20C, especially 4-15C divalent satd. alicyclic hydrocarbon group.

Description

[Detailed Description of the Invention] [Field of Commercial Use] The present invention relates to a substrate for an optical recording medium such as an optical disk or an optical card;
It relates to optical molded products such as optical elements such as lenses, prisms, and diffraction gratings.

[Conventional technology]

Conventionally, optical recording media such as optical disks and optical cards; lenses,
Glass and plastic are used as materials for optical elements such as prisms and diffraction gratings. Glass has disadvantages such as low mass production, high cost, heavy weight, and breakability, and currently plastics, which do not have these disadvantages, are the mainstream material. However, plastic generally has poor optical performance (low birefringence) compared to glass.

It is inferior in terms of heat resistance and water resistance, and there is a strong desire to improve these performances.

Currently, the plastic material used for optical molded products is polymethyl methacrylate (hereinafter referred to as polymethyl methacrylate).

This is abbreviated as PMMA. ) and bisphenol polycarbonate (hereinafter abbreviated as PC). Although PMMA has extremely low birefringence, it has a high water absorption (moisture absorption) property, and has the drawback that water absorption causes warping and deformation, which tends to cause a decrease in optical performance. In particular, PMMA
When used as a material for an optical recording medium consisting of three substrates such as an i-digital audio disc or an optical card, faithful reproduction of information may become impossible. Also, PM
Optical molded products using MA also have problems with heat resistance. On the other hand, PC has low water absorption, almost no water absorption, and has no problems with heat resistance.

It has the disadvantage of high birefringence. For digital audio discs and small-diameter lenses, it is possible to suppress birefringence to below the required level by controlling the molding conditions with high precision, but for 30 mm diameter laser vision and large-diameter lenses, the molding conditions must be controlled with high precision. It is extremely difficult to control with high precision. In addition, since PC has a low surface hardness and is easily scratched, there is concern about long-term use of molded products for nine optics using PC.

Polycarbonate obtained from 2,2.4.4-tetramethyl-1,3-cyclobutanediol (hereinafter abbreviated as TMCD) and polycarbonate obtained from TMCD and dihydric phenol have a high glass transition temperature and are heat resistant. It has been reported that it can be used as a molding material for optical parts because it has good properties, reduced birefringence, and high transparency (Japanese Patent Laid-Open No. 63-92644
(See Publication No. 1tt).

Conventionally, the glass transition if of polyesters having a norbornane skeleton, a perhydrodimethanonaphthalene skeleton, or a perhydrodrimetanoanthracene skeleton increases in the order of these skeletons, and these polyesters have a higher temperature than polyesters without these skeletons. It has been reported that the polymer has a high glass transition temperature [Journal of Polymer Science;
5science: Pol)mer Chemis
tryEdition), volume 10, page 3191 (I9
1972)].

Further, polyester having the above-mentioned skeleton has excellent dimensional stability and is known to be used for substrates of photographic films, etc. (see US Patent No. 896.033).

[Problem to be solved by the invention]

As mentioned above, PMMA, which has been conventionally used as a material for optical molded products, has the disadvantage of insufficient heat resistance, and PC has the disadvantage of large optical distortion (birefringence). . Therefore.

Since the use of optical molded products made of PMMA or PC is limited depending on the usage situation, the emergence of optical molded products with excellent transparency and heat resistance and low optical distortion is required. The current situation is what is desired.

An object of the present invention is to provide an optical molded article that has excellent transparency and heat resistance, has small optical distortion, has low water absorption, and has very little water absorption.

[Means to solve the problem]

According to the present invention, the above object is achieved in that the main chain consists essentially of the following repeating units (I).

A in the above repeating unit (I) is a divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms or 2 to 20 carbon atoms.
A divalent saturated alicyclic hydrocarbon group having 2 to 10 carbon atoms or a divalent saturated alicyclic hydrocarbon group having 4 to 15 carbon atoms is preferred. It is preferable if

A preferred example of A is shown below.

(I) A is divalent fj! When representing an aliphatic hydrocarbon group -CH2C)12- -CH2CH2CH2-, -a(
zk'k12￥1H2-CH3 -CH2CHCHt+, -CH2CH2-%CHz+
, -CH2+CHz promotion 2-1 (Narijo 2n represents 0.1 or 2, A represents a divalent saturated aliphatic hydrocarbon group or a saturated alicyclic hydrocarbon group.) Molecular weight 10,000 ~ ioo, o
o.

Providing optical molded products made from polyester resin (ii
) When A represents a divalent saturated alicyclic hydrocarbon group Furthermore, the following A provides the polyester resin of the present invention with oil resistance and extremely low water absorption.

-cH25CH2- The following divalent saturated aliphatic hydrocarbon groups and saturated alicyclic hydrocarbon groups in 1% of the above A give the polyester resin in the present invention excellent heat resistance and low water absorption. Moreover, a polyester resin having such A can be produced with good polymerization reactivity.

-CH2CH2--CH2CH2CH2-1-CH2+
CH2-yM2-CH3 A may be 1 ais, or two or more types may be mixed.

Further, n in the alternating unit (i) is preferably 1 or 2 from the viewpoint of the heat resistance and water absorbency of the polyester resin. On the other hand, from the viewpoint of manufacturing cost of dicarboxylic acid or its ester as a raw material, it is better for n to be small. In view of the balance between the performance and manufacturing cost of the polyester resin, it is preferable that n is 1.

Further, the polyester resin in the present invention may have other arbitrary structural units in an amount within a range that does not impair its properties, for example, about 10 molti or less based on the total amount.

The polyester resin in the present invention has a polystyrene-equivalent number average molecular weight of 1 as determined by gel permeation chromatography (hereinafter referred to as GPC).
It is in the range of 0,000 to 100,000.

The number average molecular weight of the polyester m fat in the present invention is 1
It is preferably in the range of 5,000 to 80,000, more preferably in the range of 20,000 to so, ooo. In the case of a resin with a number average molecular weight smaller than 10.000, the mechanical strength of the obtained molded product is not necessarily sufficient, and in the case of a resin larger than IOO or OCO, it may be difficult to form the optical component. This is not desirable because the properties are insufficient.

The polyester resin in the present invention can be produced according to a known method. For example, a dicarboxylic acid represented by general II (n) (wherein n is as defined in @) [hereinafter abbreviated as dicarboxylic acid (II)] and a general formula (Il!DHO-A Dehydration reaction from a dihydroxyl compound (hereinafter abbreviated as dihydroxyl compound (2)) represented by -OH(IID (in the formula, A is as defined above)), dicarboxylic acid (IO Dialkyl esters and dihydroxydyl compounds (
2) Dealcoholization reaction from dicarvone! * (II
, ) and dihydroxyl compounds (dehydrochlorination reaction from the book, dealkali metal chloride reaction from alkali metal salts of dicarboxylic acid (n) chloride and dihydrokymol compound Tsukuda) as necessary. The polyester resin of the present invention can be produced by carrying out the reaction in the presence of a suitable catalyst.

As for the form of the reaction, methods such as a melt method and a solution method can be adopted depending on the type of reaction, but the melt method is preferable because of the ease of reaction.

Hereinafter, a case will be described in which the polyester resin used in the misfire 8A technique is used as a raw material, and a dialkyl ester of dicarboxylic acid (I1) and a dihydroxyl compound Qll) are produced by a melting method by a dealcoholization reaction. Examples of catalysts include tetraalkyl orthobutanoates; zinc acetate; antimony oxide; germanium oxide; flucoxides such as potassium t-butoxide and sodium methoxide; alkali metals such as lithium and sodium; alkalis such as lithium hydride and sodium hydride. Metal hydrides; alkali metal hydroxides such as lithium hydroxide and sodium hydroxide; metal halides, etc. are used. The amount of catalyst used is usually 0.0001% of the total raw material.
It is in the range of ~1 mole. If the amount of catalyst used is less than the above range, the reaction rate will be extremely reduced, and if the amount of catalyst used is more than the above range, the water absorption rate of the resulting polyester resin will increase. or may cause discoloration.

The polycondensation reaction is carried out by stirring the raw material compounds while heating in the presence of a catalyst in an inert gas atmosphere such as nitrogen, argon, carbon dioxide, etc., and distilling off the generated alcohol. The reaction temperature varies depending on the raw material compound used and the boiling point of the alcohol produced, but is usually 150 to 30
It is in the range of 0°C. The reaction time is usually selected within the range of 30 minutes to 10 hours. In the latter half of the reaction, the pressure of the system is reduced as necessary to drive the reaction. The pressure at this time is usually 0.0
The range is 01 to 100wi, Hf. After the reaction is complete, the resulting resin is extruded from the reactor in the form of a strand and then pelletized using a pelletizer, or in the form of a lump.
Take out D and crush.

The polyester resin produced as described above can be molded into an optical molded article by any known method, for example, melt molding methods such as press molding, extrusion molding, injection molding, and injection compression molding. In the case of melt molding, the resin temperature is usually set in the range of 200 to 400°C, and the mold temperature is set in the range of 40 to 200°C. During molding, heat stabilizers, light stabilizers, antistatic agents, lubricants, inorganic or organic fillers, dyes, pigments, etc. may be added to the polyester resin as necessary. Once polyester resin is formed into a flat plate or simple shape, it can be laminated with inorganic or organic materials, or it can be made into complex shapes by adhesion or fusion, or it can be subjected to high-order processing such as embossing on the surface. It is also possible to apply

For example, when polyester resin is used as a material for a substrate for a read-only optical recording medium, the substrate is first obtained by molding the polyester resin by injection molding using a mold in which groups, signals, etc. are recorded. . On this substrate, a metal such as aluminum is deposited on the information surface by a method such as vacuum evaporation, and then a protective polymer layer is formed, or the information surface on which the surface is made of metal is coated face-to-face. Paste the two sheets together. The information recording layer may be provided on a flat substrate made of polyester resin by a 2P method using a photocurable resin. Further, the information recording layer can also be formed by, for example, providing a thin film of an inorganic material such as tellurium oxide or terbium-iron-cobalt alloy or an organic material such as cyanine dye on the surface of a molded substrate. Note that the term "substrate for optical recording media" specifically refers to a substrate such as an optical disk substrate, an optical card substrate, etc., in which information is recorded and/or read out physically or chemically using a laser beam that passes through the substrate. refers to the substrate used as a medium for Also,
Its shape may be disc-like or card-like.

Further, after forming a polyester resin into a lens, a diffraction grating, etc., a treatment such as providing an antireflection film on the surface by vacuum deposition or the like can be performed.

Examples of the optical molded article of the present invention include the following.

(I) Diffraction gratings for optical disk player pickups, spectroscopic elements, optical low-pass filters, etc. (2) Substrates for optical recording media such as optical disks and nine cards (8) Glasses, cameras, loupes, projection televisions, etc. (4) Various optical elements such as prisms, optical waveguides, beam scatterers, etc. (6) Covers for automobile headlamps, rear lamps, etc. (6) Various lighting equipment parts (a) Glass substitutes for windows, windshields, etc. 8
) Various signboards [Examples] The present invention will be specifically explained below using Examples.

In addition, the physical property values were measured according to the following method.

(2) Number average molecular weight, determined by GPC (polystyrene equivalent).

■Glass transition temperature: Differential thermal analysis method (in nitrogen, heating rate 1
0° C./m1n).

(2) Light transmittance: The transmittance of light at wavelengths of 400f1m%, 600 nm and 800 nm of a sample molded to a thickness of 2 ym by hot pressing was measured using a spectrophotometer.

■Retardation C birefringence): diameter 4Qmm, thickness 6
The sample molded to .
891m).

■Surface hardness: Lead wheel hardness test (JIS K5400)
I asked for help.

(2) Saturated water absorption rate: Measured by determining the weight increase rate when no weight increase due to water absorption was observed in distilled water at 23°C. The saturated water absorption rate of bisphenol A polycarbonate determined by this measurement method is 0.40.
It was Chi.

■Water absorption warping: Warping (lifting in the center) caused by vacuum-depositing aluminum to a thickness of 100λ on one side of a 2α×10(7)×2■-thick plate sample and immersing it in distilled water at 23°C. The maximum value of was taken as water absorption warpage.

Synthesis of Polymer Synthesis Example 1 In a reaction tank with an internal volume of 8 tons and equipped with a double helical ribbon stirring stem, 2.43 dimethyl perhydro-1,4:5,8-dimethanonaphthalene-2,3-dicarboxylate and 4r, 1 were added.
．． After charging 1.57 k of 4-cyclohexane dimetatool and 2.5 k of tetrainpropylorntemenate and thoroughly purging the system with nitrogen gas, the temperature of the oil bath in the reaction tank was set to 200°C. It was held for 60 minutes. The reaction was carried out at 230°C for 30 minutes, at 240°C for 30 minutes, and at 250°C for 60 minutes while stirring at a speed of 70 revolutions per minute. The methanol distillation amount at this point was 0.65 kf (
The theoretical amount was 93 h). Next, while maintaining the temperature at 250°C, the system was reduced to a degree of vacuum of 0.3 H2 and reacted for 5 hours.

After the reaction was completed, the shibolimer was weired out of the reaction tank in the form of a strand and cut into pellets. The obtained polymer was pale yellow and transparent, and had a number average molecular weight of 28,000. Also, the polymer yield was 2.91 hooves. Table 1 shows various physical properties of the obtained polymer.

Synthesis Example 2 Verhydro-1,4:5.
Diethyl 8-dimethanonaphthalene-2,3-dicarboxylate 2.60 kr,) cyclodecane dimethanol (mixture of each isomer) 1.17-11.4-butanediol 0.23 kF and tetraptyl ornchita+ -G2.
of was charged and the reaction was carried out under the same conditions as in Synthesis Example IK.
A number average molecule f124,000) was obtained. Table 1 shows various physical properties of the obtained polymer.

Synthesis Example 3 In the reaction tank used in Synthesis Example 1, Berhydro-1,4:5,
8:9,10-) diethyl dimethanolanthracene-2,3-dicarboxylate 2.98 kF, 1,4-cyclohexane dimetatool 0.81 kt, 1,4-butanediol 0.22 kF and tetrabutylorne titane -)3
．． 3y was charged, the reaction was carried out under the same conditions as in Synthesis Example 1, and a pellet-like polymer 3.071?
(number average molecular weight 22,000) was obtained.

Table 1 shows various physical properties of the obtained polymer.

Synthesis Example 4 Into the reaction tank used in Synthesis Example 1, dimethyl norbornane-2゜3-dicarboxylate 0.87) #, bevel draw 1,4
: 5,8 : 9.10-) Dimethanoanthracene-2,3-dicarboxylic acid diethyl 2.28 ky, ethylene glycol 0.32 kr, 2,2-dimethyl-
1,3-propanediol 0.53 k7 and tetraisoprovil orthotitanate) 2.3F were charged, the reaction was carried out under the same conditions as in Synthesis Example 1, and the pellet-shaped polymer 2.9 i 1qy Cfi was prepared in the same manner. An average molecular weight of only 27,000) was obtained. Table 1 shows the properties of each of the obtained polymers.

Example 1 The polymer obtained in Synthesis Example 1 was converted into 5IJ manufactured by Technoplus Co., Ltd.
Molded by VI-4749A injection molding machine with outer diameter of 13clR.

A substrate was obtained by injection molding to have an inner diameter of 1.5 m and a thickness of 1.2 M. Films of aluminum nitride-silicon/terbium-iron-cobalt/aluminum 9-mu-silicon nitride were sequentially formed on this substrate by sputtering, and the writing/reading/erasing characteristics of the magneto-optical disk were evaluated. The N ratio was 50 dB. Furthermore, the C/N ratio after 1 million write/read/erase operations is 46 dB. Furthermore, the C/N ratio after storage for 1000 hours at 75° C. and 85° RH was as good as 45 dB.

Example 2 Using the polymer obtained in Synthesis Example 2, the characteristics as a magneto-optical disk were evaluated in the same manner as in Example IK. As a result, the C/N ratio of the read signal was 51 dB and 1
The C/N ratio after 1,000,000 repeated tests is 47dB.
After storage for 1000 hours at 75° C. and 85° RH, the C7N ratio was as good as 45 dB.

Example 3 Using the polymer obtained in Synthesis Example 3, the characteristics as a magneto-optical disk were evaluated in the same manner as in Example 1. As a result, the C/N ratio of the read signal was 59 dB, fi,
The C/N ratio after the test was repeated 1 million times was 47 dB, and the C/N ratio after being stored at 75° C. and 854 RH for 1000 hours was as good as 45 dB.

Comparative Example 1 Polycarbonate (Teijin Kasei Panrai AD5503) was used as the polymer, and the characteristics as a magneto-optical disk were evaluated in the same manner as in Example 1. As a result, the C/N ratio of the read signal was 45 dB, and the ioo The C7N ratio after 10,000 repetitions test was 40dB, 75℃%8
The C/N ratio after storage for 1000 hours at 5% RH was 4QdB.

Example 4 and Comparative Example 2 The polymer obtained in Synthesis Example 1 was molded and 1% was molded onto a smooth substrate according to the method described in Japanese Patent No. 62-95525.
Copolymer of 2-butenyl methacrylate and methyl methacrylate (copolymerization molar ratio 1:3.3, molecular weight 200,000
) and 1 part by weight of 3-benzoylbenzophenone to form a thin film, and then pattern exposure was performed by irradiating ultraviolet rays through a photomask for a diffraction grating. Next, a diffraction grating was prepared by vacuum drying at 95° C. to remove uncured 3-benzoylbenzophenone. There was virtually no change in wavefront aberration before and after being left for 24 hours under conditions of 40° C. and 954 RH (Example 4).

For comparison, when a diffraction grating was similarly prepared using polymethyl methacrylate as a substrate and evaluated, the wavefront aberration increased (Comparative Example 2).

〔Effect of the invention〕

According to the present invention, a molded article having the following characteristics is provided.

■Light transmittance is 90 inches or more (2 inch thick, wavelength so on
m) and high.

(2) It has a glass transition point of 110°C or higher and exhibits good heat resistance.

■Saturated water absorption rate is low at 0.3% or less.

(2) The C/N ratio of the read signal is 4 dB higher than when a substrate made of bisphenol A polycarbonate is used as the pupil of the magneto-optical disk.

■When used as a diffraction grating substrate, 40℃, 954R
The wavefront aberration does not substantially change before and after being left at H for 24 hours.

Patent applicant RiRashi Co., Ltd.

Claims (1)

[Claims] The main chain is substantially the following repeating unit (I) (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, n represents 0.1 or 2, and A is a divalent represents a saturated aliphatic hydrocarbon group or a saturated alicyclic hydrocarbon group) with a number average molecular weight of 10,000 to 100,0.
Optical molded product made from 00 polyester resin.