JPS624711A - Production of acrylic graft copolymer - Google Patents

Abstract

PURPOSE:To obtain a lowly hygroscopic acrylic resin good in optical properties, heat resistance and mechanical strength, by polymerizing or copolymerizing a specified methacrylate ester monomer. CONSTITUTION:25-100wt% methacrylate ester of formula I or monomer mixture thereof with a methacrylate ester of formula II is copolymerized with 0-75wt% methyl methacrylate and 0-40wt% otyer unsaturated monomers copolymerizable therewith. In the formulae, R1, R2, R3, R4 and R5 are each H, halogen cyano, 1-5C alkyl or alkoxy, n is 0 or 1, and R is 6-20C alicyclic hydrocarbon.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a low-hygroscopic acrylic resin with good optical properties, heat resistance, and mechanical strength, which can be used as a material for optical equipment such as plastic lenses and prisms. The present invention also relates to a method for producing resin materials suitable for optical recording substrates such as video discs and information discs.

Deacrylic resin, which is mainly composed of methyl methacrylate, has excellent transparency and weather resistance, and has well-balanced properties such as mechanical properties, heat resistance, and moldability, and is widely used as a molding material. However, it has the disadvantage that it has relatively high water absorption and hygroscopicity, causing warping and deformation of molded products.

For example, polymers mainly composed of methyl methacrylate have little optical anisotropy caused by birefringence that occurs during injection molding, and have recently attracted attention. Although it is used in discs and information discs, it has poor dimensional stability due to its high hygroscopicity, and tends to warp and deform in humid environments, so improvements in these problems are strongly desired.

In order to improve this point, for example, Japanese Patent Application Laid-Open No. 57-88446
No. 57-162185 proposes a copolymer of methyl methacrylate and an aromatic vinyl monomer such as styrene. However, copolymers with aromatic vinyl monomers tend to cause birefringence and cannot be put to practical use.

Furthermore, JP-A-58-5818, JP-A-58-127
Publication No. 764 proposes a copolymer with cyclohexyl methacrylate in order to reduce hygroscopicity without worsening birefringence, but the homopolymer of cyclohexyl methacrylate is extremely brittle and glass transition It is well known that the temperature is lower than that of methyl methacrylate homopolymer, and when a large amount of cyclohexyl methacrylate is copolymerized to reduce hygroscopicity, heat resistance and mechanical strength are reduced. This causes a problem.

Furthermore, in JP-A-58-104989, in order to improve the decrease in mechanical strength that occurs when cyclohexyl methacrylate is co-supplied, a polymer containing a crosslinked acrylic ester polymer as a rubber component is blended. However, crosslinked acrylic ester rubber polymers generally have a smaller degree of improvement in 1tffi impact strength than diene rubber polymers, so they must be introduced in large amounts, which further reduces heat resistance. It's inconvenient.

(Problems to be Solved by the Invention) The problems to be solved by the present invention, that is, the purpose of the present invention, is to achieve good birefringence and heat resistance even by injection molding, compression molding, etc. The object of the present invention is to provide a low hygroscopic transparent acrylic resin with well-balanced mechanical strength and excellent dimensional stability.

Means for Solving Problem C) The present invention provides a method for solving problems of the general formula (1) (where R1, R, , R
, R, and R1 are hydrogen, halogen, a cyano group, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group. n represents an integer of 0 or 1. ) ゛ At least one methacrylic ester or the methacrylic ester represented by general formula (2) (% formula %) (wherein, R is an alicyclic alkyl group having 6 to 2 o carbon atoms.) Monomer mixture (a) consisting of methacrylic acid ester represented by 25 to 1001i mass %, methyl methacrylate f
Provided is a method for producing an acrylic graft copolymer, characterized by copolymerizing 0 to 75% by weight of BL and another unsaturated monomer copolymerizable with these (CIO-10 weight%). It is something.

The rubbery polymer used in the method of the present invention is a diene-based rubbery polymer mainly composed of a conjugated diene having a refractive index of about 1.50 or more, and examples thereof include polybutadiene, polyimprene, and polypropylene. Homopolymers such as chloroprene or conjugated diene monomers such as butadiene, imprene, chloroprene, acrylonitrile monofunctional vinyl monomers, and ethylene glycol dimethacrylate,
Examples include copolymers with polyfunctional monomers such as divinylbenzene, which have a refractive index of about 1.50 or more. It is necessary that the refractive index of the rubbery polymer used in the present invention is about 1.50 or more, and if it is smaller than about 1.50, the refractive index of the diene rubbery polymer and the (al, (bl)
It is not preferable because the difference in refractive index between the monomer and the polymer of (C1) becomes large and the transparency of the resulting co-fi gold body decreases.Methacrylic acid ester represented by general formula (1) is the heat resistance of the graft copolymer.

In addition to hygroscopic white clay, (al, (bl and (
This is an essential component in order to make the refractive index of the polymer portion (hereinafter referred to as matrix phase) made from the monomer (C) equal to that of the diene rubber-like polymer. The refractive index of the copolymer obtained by polymerizing a monomer mixture other than the methacrylic acid ester represented by general formula (1) is usually lower than the refractive index of the diene rubber-like polymer. Using the methacrylic ester represented by the general formula (1), the refractive index of the matrix phase is adjusted to be equal to the refractive index of the diene rubber polymer.

When adjusting the refractive index, change the content of methacrylic acid ester shown in general formula (1) to actually make a copolymer with other monomers, and measure the refractive index of the copolymer. The amount to be added can be easily determined by looking at the formula below, but the amount to be added may also be determined so that the refractive index of the IJx phase is equal to the refractive index of the rubbery polymer used.

nmatri) (= 's nt + (1-〆1
) nt where n: refractive index of the matrix phase atr1x nI: refractive index n of the homopolymer of methacrylic acid ester represented by general formula (1): refractive index of the polymer of the other monomer mixture to be copolymerized Refractive index: Volume fraction of component 1 Examples of the methacrylic ester represented by the general formula (1) include phenyl methacrylate, p-methylphenyl methacrylate, p-cyanophenyl methacrylate,
Examples include O-chlorophenyl methacrylate, p-bromophenyl methacrylate, p-methoxyphenyl methacrylate, benzyl methacrylate, O-chlorobenzyl methacrylate, and phenyl methacrylate is particularly preferred.

The methacrylic acid ester represented by the general formula (2) used in the present invention is methacrylic acid or its acid chloride, and the formula R
It is produced by esterifying OH with an alicyclic hydrocarbon/monol. III Cyclic hydrocarbons/monols [cyclohexanol, 4-methylcyclohexanol, l-cyclohexylethanol, norborneol, 1-adamantanol, 2-adamantanol, 3-methyl-1-adamantanol, 8.5 -dimethyl-1-adamantanol, 8-ethyladamantanol, 8-methyl-5-ethyl-1-adamantanol,
8.5.8-) diethyl-1-adamantanol and 8.5-dimethyl-8-ethyl-1-adamantanol, 8-hydroxy-tricyclo(5,2,1,02='
) Decane, octahydro-4,7-menthafindene-
1-ylmethanol, p-menthanol-8, p-menthanol-2,8-hydroxy-2,6,6-trimethyl-bicyclo(8,1,1]hebutane, 8.7.7-drimethyl-4-hydroxy -Alicyclic hydrocarbons and monomers such as bicyclo(4,1゜0)hebutane, borneol, isoporneo-nt, 2-methylcamph-Tol, fenthyl alcohol, a-menthanol, 2.2゜5-trimethylcyclohexanol, etc. Examples include methacrylic acid esters corresponding to these.

Particularly preferred among these methacrylic esters are bornyl methacrylate, inbornyl methacrylate, fenthyl methacrylate, and e-menthyl methacrylate. Adamantyl methacrylate, tricyclo methacrylate [5゜2
．． 1.0"-")-decyl-8, cyclohexyl methacrylate, and the like.

These methacrylic esters having an alicyclic hydrocarbon group having 6 to 20 carbon atoms on the alcohol side may be used alone or in combination of two or more types with the methacrylic ester represented by general formula (1). I can do it.

When a methacrylic acid ester having a ring hydrocarbon group having 10 or more carbon atoms is used on the alcohol side, it has a high contribution rate to improving heat resistance, and can be preferably used especially when heat resistance is required. In addition, when an alicyclic hydrocarbon group having more than 20 carbon atoms is used, it is not preferable because the mechanical strength of the resulting copolymer is significantly reduced. [Al monomer content in the monomer mixture serving as the matrix phase is 25 to 100% by weight, and 25% by weight
If the amount is less, the improvement in hygroscopicity will not be sufficient, which is not preferable. (The proportion of the Al monomer is preferably 85 to 80% by weight, more preferably 45 to 70% by weight in terms of the balance between low hygroscopicity and mechanical strength.

The monomer (a) forms a matrix phase by polymerizing alone or copolymerizing with methyl methacrylate (bl), where the content of methyl methacrylate (bl is 0 to 76% by weight). The content is preferably 20 to 65% by weight, particularly 80 to 55% by weight.

Furthermore, in the present invention, other vinyl monomers (C1) copolymerizable with monomers (a) and (b) may be mixed and used within a range that does not reduce the effects of the present invention. )
The content ratio is preferably 10% by weight or less. Examples of the monomer (C) include alkyl acrylate, styrene, and acrylonitrile sodium chloride, and m) methyl acrylate, ethyl acrylate, and butyl acrylate are particularly preferred as those that improve the thermal decomposition resistance of the IJx phase.

In the present invention, such a monomer mixture is polymerized in the presence of a diene-based rubbery polymer to form a matrix phase, and the diene-based rubbery polymer ultimately accounts for 1 to 20% by weight in the resin. is preferable, more preferably 2 to 1O
The weight is good. Diene-based rubbery polymer is 20fiff
If it is more than t%, the rigidity will decrease, and transparency and workability will deteriorate, which is undesirable. If it is less than 1% by weight, mechanical strength will be insufficiently improved and cracks may occur during mold release, so it is not preferable. do not have.

Further, the rubbery polymer in the matrix phase is preferably in a dispersed state with an average particle size of O.Oa to 1μ, more preferably 0.1 to 0.8μ. Average particle size is 0
．． If it is smaller than 08μ, the improvement in mechanical strength is not sufficient;
Moreover, if it is larger than 1 μm, the transparency decreases, which is not preferable.

The method for producing the graft copolymer of the present invention includes known polymerization methods using a radical initiator and, if necessary, a molecular weight regulator, such as emulsion graft polymerization, suspension graft polymerization,
It can be obtained by a solution graft polymerization method, a bulk-suspension graft polymerization method, an emulsion-suspension graft polymerization method, an emulsion-bulk graft polymerization method, or the like.

From the viewpoint of industrial productivity, all methods except the solution graft polymerization method are preferred, and when it is desired to avoid contamination with impurities as much as possible, the bulk graft polymerization method and the bulk-suspension graft polymerization method are particularly preferred.

As a specific production method, for example, in the case of emulsion graft polymerization method, potassium persulfate and sodium bisulfite or cumene hydroperoxide and formaldehyde sodium sulfoxylate in the presence of polybutadiene latex having an average particle size of 0.03 to 1 μm are used. A mixture of (al~(C1 monomers) is copolymerized at a reaction temperature of 20 to 100°C using a radical initiator such as, to obtain a graft copolymer in the form of a latex, which is then salted out and dried.

Also, if we talk about the bulk-suspension graft polymerization method,
First, polybutadiene (al~(C1) is dissolved in a monomer mixture and heated with an oil-soluble radical initiator such as azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, etc., with a conversion rate of 10 to 8 while stirring vigorously.
Proceed the reaction to 0%, then add water and dispersion stabilizer,
The system may be brought into a suspended state, the reaction may be completed while stirring, and the copolymer may be separated and dried.

Incidentally, the graft copolymer of the present invention can be obtained by the above-mentioned method 1, but the graft copolymer thus obtained and the matrix phase of the graft copolymer in the absence of a rubbery polymer are separately prepared. A polymer obtained by copolymerizing a monomer mixture may be mixed.

In addition, when molding the graft copolymer of the present invention as a molding material, particularly by injection molding, it is preferable that the molten resin viscosity of the matrix phase is low, and the molding temperature conditions etc. are optimized. When polymerizing the monomer mixture of the present invention, a molecular weight regulator is used to adjust the molecular weight without adversely affecting heat resistance, mechanical strength, etc.!
You may use it by adjusting the @ range as appropriate.

(Example) The present invention will be explained in detail below using Examples, but the present invention is not limited to the following. All parts or percentages in the examples are based on weight.

Further, the physical properties shown in Examples were measured based on the following method.

Transparency: ASTM D1008 Bending test: ASTM D790 Heat distortion temperature: ASTM D648 Melt index: ASTM D1288 (280
C, 8800f load) The adhesive tarpsion was measured at a wavelength of 546 nm using a birefringence bipolarization microscope using the Senarmont compensator method.

Water absorption rate: 60 in distilled water according to ASTM D570
The water absorption rate was measured at ℃ for 24 hours.

Maximum bending deformation rate: ASTM D790 Example 1 Methyl methacrylate 47.5 = Ji amount%, cyclohexyl methacrylate) 47.5% by weight, refractive index 1.51
5, polybutadiene rubber (diene “N” manufactured by Asahi Kasei Industries)
F-85A) 95 parts of a raw material solution consisting of 5% by weight, an initiator solution prepared by dissolving 0.1 part of lauroyl peroxide, 0.01 part of benzoyl peroxide, and 5 parts of methyl methacrylate in a 0.5N jacket. Polymerization was carried out by feeding the mixture into a complete mixing reactor with an average residence time of 180 seconds.

The polymerization temperature was 160°C, and the pressure inside the tank was 6°C.

The jacket was then heated with a heating medium at 220°C.
After passing through a back type reactor with a length of 8 ocrIK to eliminate residual catalyst, the mixture was cooled to obtain a syrup at 40°C.

The polymerization conversion rate of the monolayer in syrup is 25%, 25
The viscosity at ℃ is 23 poise, and the average particle size of the dispersed rubber particles is 0.2 μm. A polymerizable liquid composition was prepared by dissolving 20 parts of phenyl methacrylate, 2 parts of methyl acrylate, 0.8 parts of lauroyl peroxide, and 0.2 parts of lauri oligomercaptan in 78 parts of this cold syrup, and 15 parts of water.
0 part and an aqueous medium made by dissolving 0.1 part of partially saponified polyvinyl alcohol as a suspension stabilizer into a tank-type reactor equipped with an agitator, and after being stirred and dispersed, the internal temperature reaches 9o C under a nitrogen atmosphere. The mixture was heated as described above and polymerized with stirring for 1 hour and 80 minutes, and further heat treated at an internal temperature of 100° C. for 80 minutes to complete the polymerization to obtain a bead-like polymer.

This polymer was injection molded at 270° C., and a molded article with a thickness of 8 mm had a total light transmittance of 92% and a haze value of 2.0%. Also, the melt index is 4 and the heat distortion temperature is 9.
8℃9 bending strength is 750ν, maximum bending deformation rate is 8.0%
Met.

120 m in diameter using this polymer.

When a disk-shaped test piece with a thickness of 1.2 μ was injection molded, no cracks were observed during release from the mold, and the distance was 3.0 cm from the center of the molded product.
The birefringence at the position was as low as 16 parts m. Further, the water absorption rate of this disk was 0.62%, which was extremely low hygroscopicity.

Example 2 Methyl methacrylate) 48fI amount%, cyclohexyl methacrylate 24% by weight, bornyl methacrylate) 24
% by weight, 6% by weight of the polybutadiene rubber used in Example 1
Partial polymerization was carried out in exactly the same manner as in Example 1, except that 95 parts of the raw material liquid consisting of the following were used to obtain a syrup having a dispersed rubber particle size of 0.2 μm. A solution obtained by dissolving 20 parts of phenyl methacrylate, 0.8 parts of lauroyl peroxide, and 0.1 part of lauryl mercaptan in 80 parts of this syrup was poured into a glass cell after degassing, heated at 80°C for 2 hours using a 6-trowel, and heated to 120°C. The reaction was carried out for 2 hours to obtain a sheet-like polymer having a thickness of 8 mm.

A physical property test piece was prepared from a 3-inch thick sheet and the physical properties were measured.

Aging ray transmittance 92% Haze value 2.0% Melt index l Heat deformation temperature 118°C Bending strength 920ν Maximum bending deformation rate 4.6% Also, by compression press molding this sheet at 240°C, a length of 1.2 m When the birefringence of the sheet was measured, it was as small as 3 gm, and the water absorption rate was 0.60%.

Example 8 From 44% by weight of methyl methacrylate, 60% by weight of methacrylic acid ester obtained from 8-hydroxy-tricyclo(512@1, g!, 8) decane and methacrylic acid, 6% by weight of the polybutadiene used in Example 1 Partial polymerization was carried out in exactly the same manner as in Example 1 except that 95 parts of the raw material liquid was used to obtain a syrup having a dispersed rubber particle size of 0.15 μm. A solution obtained by dissolving 15 parts of phenyl methacrylate, 2 parts of methyl acrylate, 0.8 parts of lauroyl peroxide, and 0.2 parts of lauryl mercaptan in 88 parts of this syrup was subjected to suspension polymerization in the same manner as in Example 1. Obtained union.

The physical properties of the obtained graft copolymer are shown below.
2.2% melt index
4 Heat deformation temperature 115°C Bending strength Maximum bending deformation of 720 8.0% Also, when this copolymer was used to mold the same disc as in Example 1 and the birefringence was measured, it was 18 parts m. . Furthermore, the water absorption rate is 0.6
It was 0%.

Comparative Example 1 8000 F pure water was put into a 5 g reactor equipped with a stirrer, and 2 F partially saponified polyvinyl alcohol was added as a suspension stabilizer and dissolved therein.

Further, 2000f of a monomer mixture consisting of 89% by weight of methyl methacrylate, 59% by weight of cyclohexyl methacrylate, and 2 parts by weight of methyl acrylate, 4f of n-dodecyl mercaptan, and 6t of lauroyl peroxide were added to carry out suspension polymerization. Injection molding was carried out in the same manner as in Example 1, and the bending strength was measured: 480! v, the maximum bending deformation rate was as low as 1.8%. In addition, cracks occasionally occurred during disk molding. The birefringence of the disk was 18 parts m, and the water absorption rate was 0.68%.

Comparative Example 2 Methyl methacrylate 80 was prepared in exactly the same manner as Comparative Example 1.
A monomer mixture containing 20% by weight of styrene was suspension polymerized to obtain a copolymer, which was then injection molded into a disk under the same conditions as in Comparative Example 1. The birefringence of the disc was as high as 110 nm, and the water absorption was 1.82%.

Comparative Example 3 2980f pure water was put into a 5f reactor equipped with a stirrer,
This was added to an acrylic rubber emulsion (composition: n-butyl acrylate/styrene/allyl methacrylate = 72/
26/2wt%, solid content 1 degree 3g wt%, average particle size 0.1μ) 250 f, lauryl sulfate) 4
ON, 0.015 F of ferrous sulfate, 0.06 F of ethylenediaminetetraacetate-disodium salt, and 62 F of ferrous sulfate were added and dissolved. After heating to 70°C, 600 t of methyl methacrylate, cyclohexyl methacrylate
) 795 f, methyl acrylate 301, cumene hydroperoxide 4.5 f, lauryl mercaptan 45
．． The monomer mixture solution of No. 2 was continuously added for 4 hours, and the polymerization was further carried out for 8 hours. The obtained emulsion was salted out, washed, and dried to obtain a polymer. This copolymer is molded,
Physical properties were measured.

Total light transmittance 9096 i Value
2.5% Melt index 4 Degree of black deformation 95°C Bending strength 495 mm Maximum bending deformation 1.9% (Effects of the invention) Compared to Invention 1, it has lower hygroscopicity, good dimensional stability, and heat resistance. A transparent resin with excellent mechanical strength can be obtained, and even when injection molding is used for birefringence, a very good product can be obtained. For this reason, the resin material of the present invention can be suitably used for optical materials such as lenses and prisms, particularly for optical recording substrates Iζ for video discs and the like.

In particular, the graft copolymer of the present invention has a methacrylic ester having an aromatic group on the alcohol side of the ester as an essential component, but polymers having an aromatic ring generally have a large photoelastic constant in the positive state (for example, Polymer Engineering Course 2, Polymer Physics JP, 110. Published in 1988, Chidai Shokan), unlike polystyrene, etc., although it is thought that birefringence is likely to occur during molding, injection molding It was unexpected that one with low birefringence could also be obtained.

Procedural amendment (spontaneous) 5/y, 1985 (:'-'qj First License Office Attorney General Ugahibe 1, Indication of the case 1985 Patent Application No. 145887 2, Title of invention Acrylic graft Copolymer manufacturing method 8, ?ll] Relationship with the corrective party Patent applicant address Sumitomo Chemical Co., Ltd., 5-15 Kitahama, Higashi-ku, Osaka Name Patent attorney (8597) Mitsuhiro Moroishi '1LfOC ) Tsu: 0-3404 ・'A1~゛1! 5. Column 6, Detailed Description of the Invention of the Specification Subject to Amendment, Contents of the Amendment (1) "Octahydro-4,7-Mentafindene" in Lines 4 to 5 of Page 10 of the Specification -1-ylmethanol" to "octahydro-4゜7-methanoindene-1
-ilmethanol”.

(2) [Me2.6 tricyclo methacrylate[:5,2,1.0)-decyl-8] in lines 1 and 2 of page 11 of the specification ．．
02.6]-dec-8-il".

that's all

Claims (1)

[Claims] In the presence of a diene-based rubbery polymer with a refractive index of about 1.50 or more, ▲There are mathematical formulas, chemical formulas, tables, etc.▼
is hydrogen, halogen, cyano group, alkyl group having 1 to 5 carbon atoms, or alkoxy group. n represents an integer of 0 or 1. ) or the methacrylic ester and the general formula CH_2=C(CH_3)COOR (wherein, R is an alicyclic hydrocarbon group having 6 to 20 carbon atoms). A monomer mixture consisting of methacrylic acid esters (a) 25 to 100% by weight, methyl methacrylate (b)
) 0 to 75% by weight, and 0 to 10% by weight of another unsaturated monomer (C) copolymerizable with these.