JPH03160007A - Copolymer and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a novel copolymer and a method for producing the same.

[Prior art]

In recent years, optical disks have become popular as information recording media that have a particularly large storage capacity and are randomly accessible, and their popularity has been remarkable. Such optical discs are classified into read-only types, write-once-only types, and rewritable types according to their types. The playback-only type has been applied to, for example, video discs, compact discs, etc., and has come to occupy a large market. On the other hand, some of the write-once type and rewritable type have been applied to document files, computer files, video files, etc., and some have appeared on the market, but further development is underway. Substrates for such optical discs are required to have properties such as low birefringence, transparency, heat resistance, and moisture absorption resistance. In particular, write-once and rewritable types are required to have more of the above properties than playback-only types. Excellence is required. The present inventors have already proposed a compound represented by the following formula as a monomer for producing substrates for optical discs (Japanese Patent Application Laid-Open No. 64-42447).
Publication No.). The above compound (hereinafter simply referred to as a crosslinking agent)
By polymerizing a mixture of this and a copolymerizable vinyl monomer, a good optical disc substrate can be obtained. (Problems to be Solved by the Invention) However, when a mixture of a crosslinking agent and a vinyl monomer copolymerizable with the crosslinking agent is injected into a polymerization mold for cast polymerization, the shrinkage due to polymerization is large. The disadvantage was that the molded product easily peeled off from the mold during polymerization, and the guide grooves and bits could not be transferred sufficiently. One way to reduce polymerization shrinkage is to add a soluble polymer to the above mixture, but with this method, the precipitate becomes cloudy during polymerization, impairing its transparency. There was a problem. Another possible method is to add a macromonomer with one polymerizable group to the end of the polymer. However, when the present inventors tried this method, they found that although the transparency was not impaired if it was added in a small amount, a sufficient effect on polymerization shrinkage was not obtained, and that when a large amount was added, the polymerization shrinkage was reduced. Similar to the case where the above-mentioned polymer is added, there is a problem that the precipitate becomes cloudy, and there are also disadvantages such as a lack of heat resistance.

(Means for Solving the Problems) In view of the above-mentioned problems, the present inventors have developed a polymer that is soluble in vinyl monomers, has a sufficient effect in reducing polymerization shrinkage, and has a sufficient effect on reducing polymerization shrinkage. We have been searching for polymers that do not impair transparency and heat resistance. As a result, we have succeeded in creating a new polymer that achieves the above objectives, and by copolymerizing this with a crosslinking agent and a vinyl monomer, we have achieved transparency, heat resistance, birefringence, and moisture absorption resistance. The present inventors have discovered that an excellent optical disc substrate can be provided, and have proposed the present invention.

That is, the present invention consists of 2 to 90 mol% of monomer units represented by the following formula (a) general formula and (b) 98 to 10 mol% of monomer units represented by general formula R3. This is a copolymer with special characteristics.

R in the general formula (I) of the present invention and the general formula (I)
The alkyl group represented by Y in I) is not particularly limited, but generally a linear or branched saturated hydrocarbon group having 1 to 4 carbon atoms is preferred, and specifically, a methyl group,
Ethyl group, n-probyl group, iso-probyl group, n-
Examples include butyl group and t-butyl group.

In addition, in the general formula (1), n represents an integer of 1 or more, but if it exceeds 10, the heat resistance will deteriorate, so n should be 1-1.
An integer of 0 is preferable, and an integer of 1 to 3 is preferable from the viewpoint of easy availability of raw materials.

The monomer unit represented by the general formula (1) and the general formula (
The ratio of monomer units shown in II) is 2 to 90 for the former.
mol %, the latter should be 98-10 mol %. If the amount of the monomer unit represented by the general formula (1) is too small, the transparency and heat resistance of the optical disc substrate obtained using the copolymer of the present invention will decrease, while if it is too large, Since the solubility in the vinyl monomer becomes poor, a sufficient amount cannot be dissolved, and as a result, a sufficient effect of reducing polymerization shrinkage cannot be obtained. In order to obtain sufficient properties such as transparency, heat resistance, birefringence, and moisture absorption resistance of the optical disc substrate, the monomer unit represented by the general formula (1) should be 3 to 80 mol%, and is 5 to 70 mol %, and preferably the monomer unit represented by the general formula (II) is 97 to 20 mol %, more preferably 95 to 30 mol %.

The molecular weight of the copolymers of the present invention generally ranges from 10,000 to 10,000. Furthermore, the monomer units represented by the general formula [I] and the monomer units represented by the general formula (II) are arranged randomly. The copolymers of the present invention generally exist as white powders, and include benzene, toluene, methylene chloride, chloroform. It is soluble in organic solvents such as tetrahydrofuran, but methanol. Almost insoluble in alcohol such as ethanol and water.

The structure of the copolymer of the present invention can be confirmed by 'H-nuclear magnetic resonance spectrum (hereinafter simply referred to as 'H-NMR) and infrared absorption spectrum (hereinafter simply referred to as IR).

The copolymer of the present invention may be produced by any method, but the following method is generally suitably employed. That is, it is a method of cationically polymerizing a mixture of 2 to 90 mol% of a monomer represented by the following formula and 98 to 10 mol% of a monomer represented by the following formula R3.

Specific examples of the compound represented by the general formula (■)' in the present invention include styryl methyl acrylate, styryl methyl ethylene glycol acrylate, styryl methyl propylene glycol acrylate, styryl methyl triethylene glycol acrylate, styryl methyl methacrylate, and styryl methyl methacrylate. Methyl ethylene glycol methacrylate Styryl methyl propylene glycol methacrylate. Styryl methyl triethylene glycol methacrylate, α-methylstyryl methyl acrylate, α-methylstyryl methylethylene glycol acrylate, α-methylstyryl methylpropylene glycol acrylate. α-methylstyrylmethyltriethylene glycol acrylate. Examples include α-methylstyryl methyl methacrylate, α-methylstyryl methyl ethylene glycol methacrylate, α-methylstyryl methyl propylene glycol methacrylate, α-methylstyryl methyl triethylene glycol meccrylate, and the like. To combine these monomers, chloromethylstyrene or isobropenylchloromethylbenzene and the specified acrylic acid, methacrylic acid, or alcohol ester thereof are mixed with pyridine. It can be obtained by reaction at room temperature or with heating in the presence of a basic catalyst such as triethylamine or sodium hydride. in this case,
It is preferable to use a solvent and a polymerization inhibitor as appropriate. Specific examples of the compound represented by the general formula (IV) in the present invention include styrene, methylstyrene, ethylstyrene, n-probylstyrene, iso-probylstyrene, n-butylstyrene. t-butylstyrene, α-
Methylstyrene, isopropenyltoluene, isopropenylethylbenzene, impropenyl-n-propylbenzene. Isofropenyl-iso-propylbenzene.
Isopropenyl-n-butylbenzene. Examples include isopropenyl-t-butylbenzene. The general formula (I
The charging molar ratio of II) and the general formula ([V) is 2/98 to 9, in order to keep the distribution of the copolymer within the range described above.
Preferably it is 0/10. The polymerization initiator in the present invention is not particularly limited as long as it is a cationic polymerization initiator. Examples of suitable initiators include phosphoric acid. Trichloroacetic acid, trifluoroacetic acid, sulfuric acid, perchloric acid. Hydrochloric acid, hydrobromic acid, nitric acid,
Protic acids such as chlorosulfonic acid, fluorosulfonic acid, p-toluenesulfonic acid; metal halides such as aluminum chloride, aluminum bromide, tin tetrachloride, boron trifluoride, boron trichloride, titanium tetrachloride; silica alumina (acidic clay), metal oxides such as molybdenum oxide; halogens such as iodine and bromine; organometallic compounds such as triethylaluminum, chlorodiethylaluminium, triethylaluminum-water, Grignard reagent; triphenylmethylcarbonium ion, tropinium Examples include salts of stable carbonium ions such as ions. Among these initiators, for polymerization with metal halides and organometallic compounds, compounds that generate protons or other cations, such as water, alcohols, halogens, alkyl halides, etc., may be used as cocatalysts. preferable. The amount of the initiator to be used is determined according to the general formula (I[[) and (I
1/1 of the total amount of monomers represented by V) 0 to 1
/1000 times the mole range.

As the solvent for the polymerization in the present invention, compounds that do not react with long carbon cations and reduce their activity are generally used. Also, a solvent that dissolves the initiator and the copolymer to be used is desirable. Examples of solvents suitably used include aromatic or aliphatic hydrocarbons such as benzene, toluene, hexane, and heptane; methylene chloride. Chloroform. Halogenated hydrocarbons such as carbon tetrachloride; nitro compounds such as nitromethane, nitroethane, and nitrobenzene; and the like.

The polymerization temperature may be selected depending on the type of initiator and solvent used and the preparation composition, and generally ranges from -100 to
Preferably it is 30°C. In particular, from the viewpoint of controlling the transfer reaction, the temperature is preferably 0° C. or lower.

Heavy. The polymerization time varies depending on the polymerization conditions, but is usually 5 minutes to 1 minute.
It is sufficient to select from the range of 0 days, preferably 1 to 40 hours. Further, it is preferable to stir during the polymerization.

The method for isolating and purifying the No-Rokurin polymer obtained by the polymerization of the present invention is not particularly limited, and any known method can be employed.
For example, after the polymerization is completed, the reaction solution is poured into a large amount of methanol, and the precipitated white powder polymer is filtered off using a glass filter, washed with methanol, and then dried under reduced pressure for purification.

The copolymer obtained by the polymerization of the present invention can be blended into various vinyl monomers as a polymerization shrinkage reducing agent and polymerized. In particular, the resin obtained by cast polymerization by blending the copolymer of the present invention with the vinyl phenyl compound described below and a vinyl monomer copolymerizable therewith has reduced polymerization shrinkage, so Since it can prevent peeling from the mold and has good birefringence, heat resistance, and moisture absorption resistance, it is suitably used as a disk substrate.

As the above-mentioned vinyl phenyl compound to be copolymerized with the copolymer of the present invention, the above-mentioned crosslinking agents and the compound vJη1 represented by the following formula are preferably used. Furthermore, the vinyl monomer copolymerizable with the above-mentioned vinyl phenyl compound is not particularly limited as long as it is a conventionally known monomer that can be subjected to cast polymerization to obtain a disk substrate, etc., such as styrene, Vinyl toluene. α-methylstyrene,
Chlorostyrene, fluorostyrene, promostyrene,
Styrene and its derivatives such as butylstyrene, trans-stilbene, divinylbenzene; methyl methacrylate, butyl methacrylate. Methacrylic acid esters and acrylic esters such as ethyl methacrylate, phenyl methacrylate, cyclohexyl meccrylate, bornyl methacrylate, methyl acrylate, and ethyl acrylate; maleic anhydride, maleic acid, and maleic acid such as phenylmaleic anhydride; Derivatives: maleimide derivatives such as N-methylmaleimide and N-phenylmaleimide, and the like.

Among these vinyl monomers, it is particularly preferable to use styrene and its derivatives in order to obtain a disk substrate that has good copolymerizability with the copolymer of the present invention and the vinyl phenyl compound and has low water absorption. .

The above-mentioned blending ratios of the copolymer of the present invention, the vinyl phenyl compound, and the vinyl monomer copolymerizable therewith can be adopted from a wide range, but generally the copolymer of the present invention has a sufficient effect of reducing polymerization shrinkage. In addition, it exhibits transparency and heat resistance. In order to obtain a disk substrate with excellent birefringence and moisture absorption resistance, the amount of the copolymer of the present invention is 5 to 40% by weight, preferably 10 to 30% by weight, and the vinyl phenyl compound is 5 to 50% by weight.
% by weight, preferably 10 to 40% by weight, copolymerizable vinyl monomer 40 to 90% by weight, preferably 50 to 70% by weight.
It is best to choose the weight percentage.

In addition, in order to improve other physical properties of the target disk substrate, other monomers that can be copolymerized with the copolymer of the present invention can also be used together.

Furthermore, the above mixture may contain an antioxidant, a light stabilizer, etc., within a range that does not impede the achievement of the objectives of the present invention. Release agent. An antistatic agent or the like may be mixed.

When obtaining a disk substrate, it is generally preferable to polymerize the above-mentioned mixture by a cast polymerization method. The cast polymerization method can be used without any particular restriction, and for example, the copolymer of the present invention, a vinyl phenyl compound, and a copolymerizable vinyl monomer are heated and mixed into a mixture, for example, bis-(4-t-
butylcyclohexyl) peroxydicarbonate. Peroxides such as penzoyl peroxide. In this method, a predetermined amount of a radical initiator such as an azo-based initiator is mixed, poured into a polymerization mold, and after defoaming, polymerization is carried out at a predetermined temperature for a predetermined time. At this time, a metal original plate with guide grooves or pits marked thereon may be used as a mold for polymerization, and the guide grooves or pits may be transferred directly to the substrate, or a cast polymer plate of a predetermined thickness may be made. After heating, a disc may be cut out from the board. In addition, a photosensitizer is mixed with a predetermined amount of a monomer mixture, and this is injected into a glass mold having a predetermined interval, and exposed to ultraviolet rays. It may also be polymerized by irradiation with radiation. (Effects) The copolymer of the present invention can be used as a polymerization shrinkage reducing agent for vinyl monomers. In particular, when the copolymer of the present invention is blended with the vinyl phenyl compound described above and a vinyl monomer copolymerizable therewith, polymerization shrinkage is reduced without impairing optical properties. Therefore, guide grooves and pits can be transferred well, and transparency is maintained. An optical disk substrate with excellent heat resistance, birefringence, and moisture absorption resistance can be obtained. The resin obtained by polymerizing a vinyl phenyl compound and a vinyl monomer copolymerizable with the copolymer using the copolymer of the present invention as a polymerization shrinkage reducing agent has the following excellent properties as an organic glass for optical use. It has the following properties. That is, normal incidence birefringence is 30 nm or less, especially 20 nm or less, oblique 30 @ incident birefringence 100 nm or less, especially 80 nm.
m or less, total light transmittance of 85% or more, especially 90% or more, glass transition temperature of 100°C or more, especially 125°C or more, and water absorption of 0.1% or less, especially 0. It has excellent physical properties such as 0.7% or less. Therefore, the copolymer of the present invention is a compound suitable for manufacturing not only optical disc substrates but also optical lenses such as eyeglass lenses and lenses for optical instruments, prisms, optical organic glasses such as optical fibers, and the like.

(Back Examples) In order to explain the present invention more specifically, Examples are listed below, but the present invention is not limited to these Examples.

In addition, in the following examples, the composition of the obtained copolymer was determined by the following method.

That is, approximately 250 μm of the copolymer of the present invention is accurately weighed and dissolved in chloroform. Add a slight excess of bromine to this solution, leave it in the refrigerator for 7 days to perform bromine addition, then pour the copolymer solution into methanol to precipitate, and then reprecipitate with chloroform-methanol for 3
Refine by repeating. The bromine-added copolymer is analyzed for bromine, the amount of isolated double bonds is determined from the bromine content, the number of moles of the monomer represented by the above general formula [I] in the copolymer is determined, and the composition ratio is determined. was calculated.

Example 1 1000 mjl! A three-necked flask was equipped with a stirrer, a nitrogen inlet tube, and a thermometer, and 200 ml of methylene chloride, 152.8 g of styrene, and 32.4 g of styrylmethyl methacrylate were added while flowing dry nitrogen. The contents were cooled to O''C with a refrigerant while flowing nitrogen, and when 2.0 mj2 of boron trifluoride diethyl ether was added using a pipette, polymerization started immediately and the temperature rose to O''C. After stirring for 7 hours with continued cooling, a viscous solution was obtained, which was poured into a large amount of methanol to precipitate the polymer. The precipitated white powder polymer was filtered off using a glass filter, washed with methanol, and then dried under reduced pressure.

The IR of this copolymer is as shown in FIG.
Absorption based on the C=○ bond of the carboxylic acid ester is observed near 720 cm-', and absorption based on the C=C bond of the isolated double bond is observed near 1630 Cl-'.

Further, the results of 'H-NMR (δ: ppm: tetramethylsilane standard, deuterated chloroform solvent) are shown in FIG. The analysis results are as follows.

(i) That is, 1. 1-1. A main chain methylene peak was observed around 7 ppm, which can be attributed to (a) and (d). A main chain methylene peak was observed around 1.7 to 2.3 ppm and can be attributed to (b) and (e).

2. The relatively sharp peak at 0 ppm can be attributed to the methyl group (j) in the methacryloyl group. The peak around 5.0 to 5.2 pp-1 can be attributed to the methylene group (8) in the benzyl group. 5.4-5
．． 6ppm and 6. 0-6. The peaks at 2 ppm can be attributed to protons (i) and protons (b) in the methacryloyl group, respectively. Also 6.3-6.
The peaks near 8 ppm and 6.8 to 7.4 ppm can be attributed to protons (C) and (f) of the aromatic ring.

In addition, in order to determine the composition ratio of monomer units based on styrene and styryl methyl methacrylate in the copolymer, isolated double bonds were quantified by the bromination method, and the ratio of both g v * rm rrt was calculated from that value. As a result, styrene:styryl methyl methacrylate=90:10 (molar ratio), that is, m:l=90:10.

Furthermore, when this substance was analyzed by gel permeation chromatography (CGPC), the number average molecular weight (M
n) was 15,000 (in terms of standard boristyrene). From the above results, this copolymer has the structure shown below (hereinafter referred to as copolymer A).

It became clear.

Examples 2 to 5 Various styrene-styrene-styryl methyl methacrylate copolymers were prepared in the same manner as in Example 1, except that the amounts of styrene and styryl methyl methacrylate and the polymerization temperature were changed as shown in Table 1. We got together. Structural formula and 'H-NMR chemical shift of the obtained copolymer. The molar ratio, IR characteristic absorption, and number average molecular weight values determined by GPC are also listed in Table 1. In addition, Examples 2 to 5
The copolymers obtained in the above are respectively referred to as copolymers BE.

Examples 6 to 11 In Example 1, styrene and styryl methyl methacrylate were replaced with styrene and styryl methyl acrylate (
Example 6), styrene and styryl methyl ethylene glycol methacrylate (Example 7), styrene and styryl methyl propylene glycol methacrylate (Example 8), styrene and styryl methyl triethylene glycol methacrylate (Example 9). α-methylstyrene and styrylmethylmethacrylate (Example 10),
Various copolymers were obtained in exactly the same manner as in Example 1, except that methylstyrene and styryl methyl methacrylate (Example 11) were used. The structural formula of the obtained copolymer is 'H-
Chemical shift in NMR. Group ratio, IR characteristic absorption, and number average by GPC. The molecular weight values are also listed in Table 2. Further, the copolymers obtained in Examples 6 to 1l are respectively referred to as copolymers F-K.

Application Examples Using the copolymers A to K of the present invention obtained in Examples 1 to 11, a vinyl phenyl compound and a vinyl monomer copolymerizable with these are blended in a predetermined ratio, and used as a polymerization initiator. , 1-hydroxyphenyl ketone 0.3
The weight parts were heated and mixed, and after defoaming, the mixture was poured into a mold composed of two glass plates and a Teflon tube, and UV polymerization was performed. After the polymerization is completed, the polymer is released from the glass mold and has a thickness of 1. A disk substrate with a diameter of 2 mm and a diameter of 130 ma+ was obtained. Table 3 shows the physical properties of the obtained disk substrate.

Examples using polystyrene and polystyrene macromer are also listed in Table 3 for comparison.

The physical properties of the obtained disc substrate material were measured by the following test method.

(i) Birefringence: Thickness 1. A 2 mm plate was made and the birefringence at normal incidence and at 30' oblique incidence was measured using a high-precision automatic birefringence measuring device.

(ii) Total light transmittance: thickness 1. 2 Make a temporary wnO and measure according to JIS-K-7105.

(in) Glass transition temperature: Measured with a differential scanning calorimeter.

d2 did.

However, d1 and d2 are each monomers. - and the specific gravity of the polymer. vinegar.

However, polystyrene macromer in the table, BVBOPP
E and BPADSME are compounds with the following structures.

0 polystyrene macromer; CH3 ■ HzC =C C O CHz CHz
PST wing 0 PST: Boristyrene molecular weight approximately 6000 O BVBOPPE [1. 1-bis(4-vinylbenzyloxyphenyl)-1 phenylethane]: O BPADSME (bisphenol A distyryl methyl ether):

[Brief explanation of the drawing]

Figures 1 and 2 are charts of the infrared absorption spectrum and 'II-nuclear magnetic resonance spectrum of the copolymer obtained in Example 1.

Claims (3)

[Claims] (1) (a) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (I) [However, R^1 and R^2 are each a hydrogen atom or a methyl group, and X is -O-, ▲ Formula There are , chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R is a hydrogen atom or an alkyl group, and n indicates an integer on one scale.)
It is. ] 2 to 90 mol% of monomer units represented by (b) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (II) [However, R^3 is a hydrogen atom or a methyl group, and Y is It is a hydrogen atom or an alkyl group. A copolymer comprising 98 to 10 mol% of monomer units represented by: ] (2) The following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [However, R^1 and R^2 are hydrogen atoms or methyl groups, respectively, and X is -O-, ▲ Numerical formulas, chemical formulas, tables, etc. There are ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R is a hydrogen atom or an alkyl group, and n indicates an integer on one scale.)
It is. ] 2 to 90 mol% of the monomer represented by the following formula ▲ Numerical formula, chemical formula, table, etc. ▼ [However, R^3 is a hydrogen atom or a methyl group, and Y is a hydrogen atom or an alkyl group.] . ] A method for producing a copolymer according to claim 1, which comprises cationically polymerizing a mixture with 98 to 10 mol % of monomers represented by the following. (3) A polymerization shrinkage reducing agent comprising the copolymer described in claim (1).