JPH0442180B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a methacrylic resin molded article having a matte surface. More specifically, a continuous phase consisting of a polymer obtained from methyl methacrylate alone or a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate, a polymer forming the continuous phase, and a specific refractive index. (meth)acrylic acid (meaning acrylic acid or methacrylic acid, hereinafter the same) ester alone or containing at least 50% by weight of at least one of the above (meth)acrylic esters, which has the following relationship and has a specific composition. A methacrylic resin molding having a matte surface obtained by stretch-molding a methacrylic resin composition comprising a dispersed phase made of a polymer obtained from a polymerizable unsaturated monomer mixture at a temperature equal to or higher than the heat distortion temperature. Regarding the manufacturing method of the product. As a method for obtaining a resin molded product with a matte surface using conventional technology, (1) a polymerizable unsaturated monomer or a partial polymer of a polymerizable unsaturated monomer is added to a mold whose surface has been previously matte; (2) A method of pressing a thermoplastic resin material onto a matte surface at a temperature higher than the heat deformation temperature of the resin material and copying the surface; (3) A method of copying the surface of the resin material. (4) An even simpler method is to apply active energy rays (low-pressure mercury lamps, carbon arc lamps, etc.) to the surface of thermoplastic resin. There is a method of obtaining a matte surface by irradiating the material with ultraviolet rays (by ultraviolet rays) and then stretch-molding it at a temperature higher than the heat distortion temperature. However, the above method requires a special process to obtain a matte surface, which complicates the manufacturing process. The object of the present invention is to create a methacrylic resin composition (hereinafter referred to as
The object of the present invention is to obtain a methacrylic resin molded product (hereinafter simply referred to as a methacrylic resin molded product) having a matte surface from a methacrylic resin material (simply referred to as a methacrylic resin material). As a result of intensive research for the above-mentioned purpose, the present inventors have discovered that a continuous phase consisting of a polymer having methyl methacrylate as the main constituent unit, and a dispersed phase consisting of a polymer of the specific (meth)acrylic ester of the present invention. The present invention was completed based on the discovery that a methacrylic resin molded product with a beautiful matte surface can be obtained by stretch-molding a methacrylic resin material composed of the following. That is, the present invention includes a polymer [A] forming a continuous phase of 80 to 99.9% by weight, and a polymer [B] forming a dispersed phase of 0.1 to 20% by weight, wherein the polymer [A] is Methyl methacrylate alone,
or a polymer obtained from a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate, and the polymer [B] has the following general formula [] [In the above formula, R ₁ represents a hydrogen atom or a methyl group,
_R2 represents a hydrocarbon group having 2 or more carbon atoms or a derivative thereof], or 50% by weight or more of the above general formula [] It is a polymer obtained from a polymerizable unsaturated monomer mixture containing at least one kind of polymerizable unsaturated monomer, and further, the refractive index n _A of the polymer [A] and the polymer [A] are A methacrylic resin composition having a matte surface, which is obtained by stretch-molding a methacrylic resin composition that satisfies the refractive index n _B of B] or the following relational expression: 0.998≦n _B /n _A ≦1.002 at a temperature higher than the heat distortion temperature. It is in the manufacturing method of resin molded products. In the present invention, the refractive index is a value measured at 20° C. with respect to the sodium D line. The present invention will be further explained below. In the present invention, the methacrylic resin material is composed of two phases: a continuous phase and a dispersed phase, with a polymer [A] forming the continuous phase and a polymer [B] forming the dispersed phase.
There is a specific relationship for the refractive index of polymer [A]
Between the refractive index n _A of the polymer [B] and the refractive index n _B of the polymer [B], n _B /
There is a relationship of 0.998≦n _B /n _A ≦1.002 for the value of n _A.
Therefore, when the methacrylic resin material provided by the present invention is not used in combination with a light diffusing agent such as titanium oxide, aluminum hydroxide, or styrene-methyl methacrylate copolymer, the resulting methacrylic resin material becomes a transparent plate. (Transparent here means that virtually no background blur is observed when the transmitted light is observed with the naked eye.) The n _B /n _A value of the methacrylic resin material is 0.998≦n _B /
n _A ≦1.002, but the n _B /n _A value is n _B /n _A <
Those in the range of 0.998 or 1.002<n _B /n _A are
The transparency of the resulting methacrylic resin material is poor, making it impossible to achieve the object of the present invention. Furthermore, in order to obtain a methacrylic resin molded product having a beautiful matte surface by stretch-molding the methacrylic resin material, it is required that the dispersed phase be uniformly dispersed in the continuous phase. Generally, it is desirable that the material be optically uniform to such an extent that no local non-uniformity is observed in the total light transmittance, light scattering properties, etc. when the transmitted light is observed with the naked eye. Further, the size of the dispersed particles of the dispersed phase when viewed microscopically is not particularly limited, but there is a preferable range. In the resin of the present invention, there are no particular restrictions on the form of the dispersed particles; if the radius of the dispersed particles is very small, the degree of surface matting of the methacrylic resin molded product is likely to be insufficient; , the surface matte state of the methacrylic resin molded product tends to deteriorate, which is not preferable. The size of the individual dispersed particles forming the dispersed phase of the present invention cannot be directly observed because the resulting methacrylic resin material is transparent, but the continuous phase formed from the same polymer as the methacrylic resin material of the present invention , and a dispersed phase, and the ratio of the refractive index of both polymers is different from that of the methacrylic resin material of the present invention. Estimated from a previously filed patent (Japanese Patent Application No. 186115-1983) regarding a light-diffusing methacrylic resin. Then, the radius is preferably 0.1 to 500 microns, more preferably 0.5 to 100 microns, when converted to the radius of an equivalent sphere having the same cross-sectional area. The methacrylic resin material of the present invention is composed of 80 to 99.9% by weight of polymer [A] forming a continuous phase and 0.1 to 20% by weight of polymer [B] forming a dispersed phase. Polymer [B] forming the dispersed phase is 0.1
If the amount of polymer [B] is less than 20% by weight, the degree of surface matteness of the methacrylic resin molded product is insufficient; on the other hand, if the amount of polymer [B] exceeds 20% by weight, the degree of surface matteness of the resulting resin molded product will be Although this is sufficient, it is generally unfavorable because it tends to deteriorate the weather resistance, solvent resistance, strength, and heat resistance of the methacrylic resin material or methacrylic resin molded product. Within the above range, it is more preferable that the amount of the polymer [A] forming the continuous phase is 90 to 99.5% by weight, and the amount of the polymer [B] forming the dispersed phase is 0.5 to 10% by weight. In the present invention, the polymer [A] forming the continuous phase of the methacrylic resin material is polymethyl methacrylate or a polymer [A] obtained from a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate. ] is formed from. Specific examples of other polymerizable unsaturated monomers that can be copolymerized with methyl methacrylate added to a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate include methyl acrylate, (Meth)acrylic acids such as ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. and a monohydric saturated alcohol, or an ester of (meth)acrylic acid and a monohydric unsaturated alcohol such as allyl (meth)acrylate, or an ester of ethylene glycol, or ethylene glycol di(meth)acrylate. ,
1,3-Butylene glycol di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylate ) esters of (meth)acrylic acid and polyhydric alcohol such as 2-hydroxypropyl acrylate, (meth)acrylic acid, styrene, and styrene derivatives. These polymerizable unsaturated monomers are added in an amount of 20% by weight or less. The amount of methyl methacrylate is 80% by weight
If it is less than that, the strength, weather resistance, and heat resistance of the resulting methacrylic resin material and molded product are likely to deteriorate, and raw material costs are likely to increase, which is not preferable. Among the polymerizable unsaturated monomers copolymerized with the above-mentioned methyl methacrylate, (meth)
Examples include esters of acrylic acid and monohydric saturated alcohols. Among these, specific examples include methyl acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Furthermore, a preferred embodiment of the present invention is that the amount of other polymerizable unsaturated monomers copolymerized with methyl methacrylate is 10% by weight or less. That is, as a preferred embodiment of the polymer [A] that forms the continuous phase of the methacrylic resin material,
Polymethyl methacrylate and methyl methacrylate
A mixture of 90% by weight or more and 10% by weight or less of a polymerizable unsaturated monomer selected from methyl acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples include polymers obtained from The polymer [B] forming the dispersed phase of the methacrylic resin material is one that satisfies the specific refractive index defined within the scope of the present invention and the polymer [A] forming the continuous phase, and has the above general formula [ ] or a polymer of at least one polymerizable unsaturated monomer represented by the general formula []
It is a polymer obtained from a mixture of polymerizable unsaturated monomers containing 50% by weight or more. Typical specific examples of the polymerizable unsaturated monomer represented by the general formula [] include the following compounds. Note that the numbers in parentheses represent the refractive index of the polymer. 2,2,2-trifluoroisopropyl methacrylate (1.4185) 2,2,2-trifluoroethyl methacrylate
(1.437) Isopropyl acrylate (1.456) 2-ethylhexyl acrylate (1.478) n-butyl acrylate (1.466) t-butyl methacrylate (1.467) Ethyl acrylate (1.4685) Isopropyl methacrylate (1.473) Monofluoroethyl methacrylate (1.478) n-hexyl methacrylate (1.481) n-butyl methacrylate (1.483) n-propyl methacrylate (1.484) ethyl methacrylate (1.485) 2-methylcyclohexyl methacrylate
(1.503) Cyclohexyl methacrylate (1.504) 2-chlorocyclohexyl methacrylate
(1.518) 2-cyclohexylcyclohexyl methacrylate
(1.518) 2-promoethyl methacrylate (1.543) Benzyl methacrylate (1.568) and isobutyl methacrylate, acrylic acid n
-hexyl, cyclohexyl acrylate, 2-ethylhexyl methacrylate, and the like. These polymerizable unsaturated monomers represented by the general formula [] may be used alone or in a suitable combination of two or more. From the perspective of the purpose of the present invention, the performance required of the polymer [B] forming the dispersed phase is that the refractive index ratio with respect to the polymer [A] forming the continuous phase is within a specific range; The primary requirement is that it can be dispersed in a preferable state in the continuous phase, but from the perspective of producing the methacrylic resin material of the present invention,
From the viewpoint of ease of handling, it is preferable that the polymer [B] is in a glass state at room temperature. Therefore, as a preferred embodiment for obtaining the methacrylic resin material of the present invention, monomers that provide a polymer with a relatively high Tg include tertiary butyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. Considering the refractive index, select a compound that will become the basic axis, and select one.
A species, a combination of two or more species, or a combination of one or more species with another compound represented by the general formula [] or other copolymerizable polymeric unsaturated monomers. producing a polymer that is in a glass state at room temperature and has a desired refractive index by polymerizing or copolymerizing with
One example of this is to use it as the polymer [B] that forms the dispersed phase. As the polymer [B] forming the dispersed phase of the methacrylic resin material, a polymer obtained by copolymerizing the polymerizable unsaturated monomer represented by the general formula [] with another polymerizable unsaturated monomer is used. In this case, specific examples of the copolymerizable polymerizable unsaturated monomer include styrene, styrene derivatives such as α-methylstyrene, methyl (meth)acrylate, or ethylene glycol di(meth)acrylate. ,
Combining (meth)acrylic acid such as 1,3-butylene glycol di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate with polyhydric alcohol Examples include esters. Among these compounds, styrene and methyl methacrylate can be cited as typical examples. The polymerizable unsaturated monomer copolymerizable with the compound represented by the general formula [] is added to the polymerizable unsaturated monomer mixture in an amount of less than 50% by weight. Addition amount of the compound represented by the general formula [] is 50% by weight
If it is less than 20%, even if the relationship of refractive index between polymer [A] and polymer [B] is within the range of the present invention, the state of dispersion of polymer [B] into polymer [A] cannot be controlled. difficult to perform and generally undesirable. Examples in which the amount of the polymerizable unsaturated monomer represented by the general formula [] added is 80% by weight or more within the above range provide examples of particularly preferred embodiments of the present invention. The continuous phase and the dispersed phase are formed from polymer [A] and polymer [B], respectively, characterized above. However, depending on the conditions for manufacturing the methacrylic resin material, a very small amount of the polymer [B] may exist in the polymer [A] that forms the continuous phase.
Alternatively, the polymer [A] may exist in a very small amount in the polymer [B] forming the dispersed phase, or the polymer [A] may be further dispersed in the polymer [B] forming the dispersed phase. However, such methacrylic resin materials are not excluded from the scope of the present invention. The methacrylic resin material is basically composed of two phases, the continuous phase and the dispersed phase as described above, but it may contain various additives that are added to normal methacrylic resin materials. Specific examples of these additives include dye antioxidants used for coloring, stabilizers such as ultraviolet absorbers, flame retardants, and release agents that facilitate the peeling of the resin from the mold. Alternatively, ordinary pigments such as titanium oxide, barium sulfate, calcium carbonate, aluminum hydroxide, etc., which are insoluble in the polymer forming the continuous phase and the dispersed phase and form a third phase, or polystyrene, styrene-methyl methacrylate, etc. Light diffusing agents such as polymers may also be mentioned as one type of additive. Generally, when a light diffusing plate to which the above-mentioned light diffusing agent is added is subjected to stretch molding, the light transmittance increases and the light diffusivity deteriorates. When a new dispersed phase consisting of the polymer [B] of the present invention is formed in such a light-diffusing resin material, it does not affect the optical properties of the methacrylic resin material at all, but it does not affect the optical properties of the methacrylic resin molded product. The surface becomes matte, which prevents the light diffusivity from worsening. As described above, a new methacrylic resin material whose optical properties are less dependent on the stretching rate, which utilizes the surface matting ability of the present invention, is also an example of the application of the present invention. The form of the methacrylic resin material is not particularly limited as long as it can be stretch-molded, but a specific example is a plate-shaped product. At this time, the thickness of the resin plate is not particularly limited, but generally
0.2 to 20 mm, and more commonly 1 to 10 mm. Next, a method for manufacturing the methacrylic resin material will be explained. The method for producing the methacrylic resin material is not particularly limited, but a preferred specific method is to use a polymer [B] that forms a dispersed phase in advance.
A polymerizable unsaturated monomer or a partial polymer thereof, a mixture of polymerizable unsaturated monomers, or a partial polymer thereof dissolved or dispersed in
Next, by polymerizing this polymerizable composition,
A method for producing a methacrylic resin material consisting of two phases: a continuous phase consisting of polymer [A] and a dispersed phase consisting of polymer [B], and a method for melt-mixing feed material [A] and polymer [B]. can be mentioned. That is, a polymer of the polymerizable unsaturated monomer represented by the general formula [] or a polymerizable unsaturated monomer mixture containing 50% by weight or more of the polymerizable unsaturated monomer represented by the general formula [] Polymer [B] 0.1 to 20% by weight obtained from methyl methacrylate to form a continuous phase [A], or a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate; Those partial polymers 80～
Formed from a continuous phase formed from polymer [A] and polymer [B] by dissolving or dispersing it in 99.9% by weight and polymerizing it in the presence of a radical polymerization initiator, usually in a mold. A methacrylic resin material composed of two dispersed phases can be produced. Polymer [B] that forms a dispersed phase in the above method
There are no particular limitations on the method for producing the polymer, and emulsion polymerization, solution polymerization, and bulk polymerization, which are usually carried out industrially, can also be employed, but suspension polymerization in an aqueous medium is generally preferred. When this suspension polymerization method is used, it is easy to handle the obtained polymer, and the polymer [B] can be dissolved or dispersed in the polymerizable composition to become the polymer [A] forming the continuous phase. It has the advantage of being relatively easy. The polymerizable composition to be modified into the polymer [A] forming the continuous phase of the methacrylic resin material includes methyl methacrylate alone or a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate; Any of these partial polymers may be used. In general, when considering productivity and the like, it is more advantageous to use a partially polymerized product. As a method for obtaining a partially polymerized product of this polymerizable composition, it is also possible to adopt a method in which a pre-produced polymer is dissolved in a polymerizable unsaturated monomer, but usually a polymerizable unsaturated monomer is used. A preferred specific example is a method in which a radical polymerization initiator is added to the mixture and the resulting composition is heated to its boiling point to obtain a partially polymerized product. The polymer [B] that forms the dispersed phase is dissolved or dispersed in the polymerizable composition that becomes the polymer [A] that forms the continuous phase, but the matte surface of the methacrylic resin molded product is optically uniform. In order to achieve this, it is preferable that the polymer [B] is uniformly dissolved in the polymerizable composition that becomes the polymer [A]. Whether the mixture is uniformly dissolved can be easily determined by the transparency of the mixture. As long as the mixture is transparent or slightly cloudy, the matte surface of the methacrylic resin molded article is generally optically uniform. A radical polymerization initiator is added to a mixture in which the polymer [B] is dissolved or dispersed in a polymerizable composition to become the polymer [A], and the mixture is poured into a desired mold and polymerized within the mold. Specific examples of polymerization initiators include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl -4-methoxyvaleronitrile), organic peroxides such as benzoyl peroxide and lauroyl peroxide, and so-called redox initiators that combine an oxidizing agent and a reducing agent. . When a redox initiator is used, heating may not be necessary during polymerization, but usually it is poured into a mold and then heated to 40°C to 150°C for polymerization. In particular, it is preferable to complete the polymerization by heating to 50° C. to 95° C. in the first stage and then heating to 100° C. to 140° C. in the second stage. In addition, a preferable example of the mold used during polymerization is a two-sided mold whose periphery is sealed with a soft gasket.
One example is a single-sided mirror-polished endless stainless steel belt that runs in the same direction and at the same speed, facing each other and having two tempered glass plates and a soft gasket sealed around the periphery. In the method for producing a methacrylic resin material as described above, a polymer [B] forming a dispersed phase is replaced with a polymer [A] forming a continuous phase with a polymerization rate of 15 to 25% by weight.
It is dissolved or dispersed in a polymerizable composition, an azo type or organic peroxide type initiator is added, and the mixture is moved in the same direction and at the same speed between two opposing sheets whose periphery is sealed with a soft gasket. A particularly preferred method of the present invention is to continuously pour the resin plate from the upstream end between endless stainless steel belts that are mirror-polished on one side, heat to complete polymerization, and continuously take out the resin plate from the downstream end. This is listed as an embodiment. Next, in order to obtain the methacrylic resin molded product having a matte surface of the present invention from the methacrylic resin material obtained as described above, the methacrylic resin material obtained by the manufacturing method described above is Stretch molding is performed at a temperature higher than the heat distortion temperature. In the methacrylic resin material obtained by the above method, the refractive index n _A of the polymer [A] forming the continuous phase and the refractive index n _B of the polymer [B] forming the dispersed phase are n _A / n _B value of 0.998. ≦
Since n _B /n _A is in the range of 1.002, the resulting methacrylic resin material becomes a transparent resin plate when not used in combination with other light diffusing agents. This methacrylic resin material is heated at a temperature higher than the heat distortion temperature, usually at least 10℃ higher.
A methacrylic resin molded product with a matte surface is obtained by stretch-molding by plane biaxial stretching, plane uniaxial stretching, curved surface biaxial stretching, curved surface uniaxial stretching, etc. using a tenter method or the like. The heat distortion temperature referred to here is ASTM
Shows the deflection temperature measured at D 648-45T.
Specific examples of biaxial stretching include common forming methods such as free blow molding, vacuum forming, and finish forming. The extent to which the surface is matte is the stretching ratio ({√ ₀
-1}×100%. d ₀ indicates the plate thickness before stretch forming, and d indicates the plate thickness after stretch forming. ) is 0
% to about 50%, the degree of surface matting gradually becomes noticeable as the stretching ratio changes, but when it increases to about 50% or more, the degree of surface matting that accompanies changes in the stretching ratio becomes gradual. The present invention will be explained below based on Examples. In the examples, % means % by weight, and parts means parts by weight. The glossiness was measured using a Tokyo Denshoku gloss meter at an incident angle of 60° and a reflection angle of 60°. The intrinsic viscosity of the polymer that becomes the dispersed phase is the value measured in chloroform at 25°C, and the total light transmittance of the resin is the JIS
Measured based on K 7105. Example 1 (1) Production of methacrylic cyclohexyl-tertiary butyl methacrylate copolymer [polymer (B) forming the dispersed phase] Equipped with a jacket equipped with a stirrer and a temperature sensor 50
In the autoclave Monomer phase cyclohexyl methacrylate Tertiary butyl methacrylate n-octyl mercaptane n-octyl mercaptane 2,2-azobis(isobutyronitrile) 13Kg (65 parts) 7Kg (35 parts) 0.4Kg (2 parts) 0.02 Kg (0.1 part) Dispersion medium Deionized sodium hydrosulfate Dispersion stabilizer (Methyl methacrylate and potassium (copolymer of methyl methacrylate and potassium sulfopropyl methacrylate) 30
Kg (150 parts), 0.1Kg (0.5 parts), 0.004Kg (0.02 parts), and while stirring at 200 rpm, nitrogen purge was carried out for 20 minutes.
Polymerization is carried out for 1 minute, and then hot water at 80°C is circulated to carry out polymerization. Check the peak of polymerization exotherm after 90 minutes,
When the temperature inside the pot drops below the temperature of the circulating water, the temperature is maintained at 115°C for 30 minutes using steam heating to complete the polymerization. Water was poured into the jacket to cool the contents, and the resulting copolymer was washed and dried at 60°C. Furthermore, this cyclohexyl methacrylate
The intrinsic viscosity of the tertiary butyl methacrylate copolymer was 0.0082/g. (2) Production of methacrylic resin material According to the conventional method, methyl methacrylate partial polymer (polymer content
21%) 96 parts cyclohexyl methacrylate-tertiary butyl methacrylate copolymer obtained in (1) 4 parts 2,2-azobis(2,4-dimethylvaleronitrile) 0.05 parts Tinuvin P (UV absorber manufactured by Ciba Geigy) agent)
A transparent composition consisting of 0.001 part of sodium dioctyl sulfosuccinate (release agent) is poured into the solution and left in a water bath kept at 82°C for 1 hour. Thereafter, the mixture was kept in a hot air circulation oven at 120°C for 2 hours to complete polymerization. In this way, a transparent methacrylic resin material with a thickness of 3 mm and no visible optical unevenness was obtained. The resin material had n _B /n _A of 0.999 and a heat distortion temperature of 91°C. (3) The 3 mm thick transparent methacrylic resin material obtained in (2) above was pushed up and molded at 170°C to obtain a methacrylic resin molded product with a beautiful matte surface. Table 1 shows the properties of the resin plate before and after stretch molding.

[Table] Examples 2 to 6, Comparative Example 1 Two endless stainless steel belts facing each other and traveling in the same direction at the same speed, the periphery of which is sealed with a soft gasket according to a conventional method. 2,2'-azobis(2,2'-azobis(2, 4-dimethylvaleronitrile) 0.05 part Tinuvin P (UV absorber manufactured by Ciba Geigy)
A transparent composition consisting of 0.01 part of sodium dioctyl sulfosuccinate (release agent) is injected, and after passing through a warm water shower zone at 82°C for 28 minutes, it is passed through a far-infrared heater heating zone where it is heated to a maximum temperature of 125°C and a gradual By passing through the cold zone for 14 minutes, a transparent methacrylic resin material with a thickness of 3 mm and no visible optical unevenness was obtained continuously from downstream. The obtained 3mm thick methacrylic resin material was heated to 170℃.
Stretch molding was performed to obtain a methacrylic resin molded product with a matte surface. Table 2 shows the optical properties before and after push-up molding.

[Table] Examples 7 to 9 In (1) of Example 1, the same operations were repeated except that the polymerizable unsaturated monomer mixture had the composition shown in Table 3, and the polymers forming the dispersed phase were obtained. A polymer [B] was obtained. Further, using the obtained copolymer, the same operation as in Example 1 (2) was repeated to obtain a 3 mm
A thick transparent methacrylic resin material was obtained, and this methacrylic resin material was further heated to 170°C and stretch-molded to obtain a methacrylic resin molded product with a beautiful matte surface. The results are shown in Table 3.

[Table] Example 10 Methyl methacrylate partial polymer (polymer content
6.5%) 95 parts cyclohexyl methacrylate-tertiary butyl methacrylate copolymer 5 parts (cyclohexyl methacrylate/tertiary butyl methacrylate weight ratio 65/35 intrinsic viscosity number 0.0082/g) 2,2'-azobis (2 , 4-dimethylvaleronitrile 0.025 parts Tinuvin P (UV absorber manufactured by Ciba Geigy)
0.01 part titanium oxide (“TITAC R-” manufactured by Sakai Chemical Industry Co., Ltd.)
550" (particle size 0.3-0.5 microns) was injected, immersed in a 65°C water bath for 5 hours, and then heated in a 120°C air bath for 2 hours to complete polymerization and form a 3mm thick sample. A white opaque methacrylic resin material with specular luster was obtained. The heat distortion temperature of the obtained methacrylic resin material was
It was 105℃. This methacrylic resin material was heated to 180°C in a hot air circulating oven, and then free blow molded into a hemispherical shape to obtain a methacrylic resin molded product with a beautiful matte surface. Comparative Example 2 The same procedure as in Example 10 was repeated except that the cyclohexyl methacrylate-tertiary butyl methacrylate copolymer was removed from the composition to be injected, to obtain a white opaque methacrylic resin material with a heat distortion temperature of 105°C. Ta. This methacrylic resin material was heated to 180° C. in the same manner as in Example 10, and then free blow molded into a hemispherical shape, resulting in a methacrylic resin molded product whose surface maintained a mirror gloss. Comparative Example 3 In a cell composed of two pieces of tempered glass and a gasket, 98 parts of methyl methacrylate-ethyl acrylate partial polymer (charged weight ratio 98/2) and polytertiarybutyl methacrylate (intrinsic viscosity number
0.015/g) 2 parts 2,2'-azobis(2,4-dimethylvaleronitrile) 0.045 parts sodium di-octylsulfosuccinate (stripping agent) 0.001 parts was injected and the same procedure as in Example 1 was carried out. Polymerization was carried out to obtain a 4 mm thick opaque resin plate with specular gloss. The n _B /n _A of this resin plate is
It was 0.983. This resin plate was placed in a hot air circulation furnace for 150 min.
After heating to ℃, free blow molding was performed into a hemispherical shape, and the obtained molded product became an opaque light-diffusing matte plate. Comparative Example 4 A resin plate containing 99 parts of polymethyl methacrylate as a continuous phase and 1 part of cyclohexyl methacrylate-benzyl methacrylate copolymer (charged weight ratio 70/30) as a dispersed phase was produced in the same manner as in Example 1. . This resin plate was opaque, and n _B /n _A was 1.021.
When this resin plate was subjected to push-up molding at 140°C with a stretching ratio of 81%, the gloss level decreased from 100% to 20%.

Claims (1)

[Scope of Claims] 1. A polymer [A] comprising a polymer [A] forming a continuous phase of 80 to 99.9% by weight and a polymer [B] forming a dispersed phase of 0.1 to 20% by weight; ] is a polymer obtained from methyl methacrylate alone or a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate, and the polymer [B] has the following general formula [] [In the above formula, R ₁ represents a hydrogen atom or a methyl group,
_R2 represents a hydrocarbon group having 2 or more carbon atoms or a derivative thereof], or 50% by weight or more of the above general formula [] It is a polymer obtained from a polymerizable unsaturated monomer mixture containing at least one kind of polymerizable unsaturated monomer, and the refractive index nA of the polymer [A] and the polymer [B ] A methacrylic resin having a matte surface, characterized in that a methacrylic resin composition whose refractive index nB satisfies the following relational expression: 0.998≦nB/nA≦1.002 is stretch-molded at a temperature equal to or higher than the heat distortion temperature. Method of manufacturing molded products.