JPH0153900B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a synthetic resin molded article having a novel matte surface. More specifically, a continuous phase consisting of a polymer whose main constituent unit is methyl methacrylate, and a dispersed phase consisting of a polymer of a certain (meth)acrylic acid (acrylic acid or methacrylic acid, hereinafter the same) ester. The present invention relates to a methacrylic resin molded product having a beautiful matte surface obtained by stretch-molding a light-diffusing methacrylic resin material composed of the following. Methacrylic resin molded products have excellent gloss and
Due to their weather resistance and weatherability, they are used for a variety of purposes, and among them, those with milky-tone light diffusing properties are often used for lighting materials, lamps, signboards, etc. When such a milk-and-half tone methacrylic resin molded product is used for lighting materials, light fixtures, etc., it is often preferred that the surface of the resin molded product has a matte finish. This is due to the superior effect provided by the matte surface, which reduces reflections on the surface when viewed in reflected light, and improves light diffusivity when viewed in transmitted light without reducing brightness. Conventionally, in order to manufacture resin molded products with matte surfaces, the methods of pouring a monomer or its partial polymer into a mold with a matte surface in advance and polymerizing it to copy the surface of the mold, and thermoplastic synthetic resins were used. A method of heating the resin to a temperature higher than its thermal deformation temperature and then copying the surface by pressing it onto a surface whose surface has been made matte in advance, or damaging the surface by bringing fine particles such as carborundum into contact with the resin surface. Furthermore, a matte surface can be created by pouring a monomer or its partial polymer added with an inorganic pigment such as barium sulfate into a mold, polymerizing it, and stretching and molding the resulting resin plate. A method of manufacturing a synthetic resin molded product having the following characteristics has been adopted. However, these conventional techniques have the following drawbacks, which severely restrict their use. In other words, the method of adding an inorganic pigment to create a matte appearance during stretch molding includes:
It is difficult to obtain a beautiful matte surface due to unevenness of matte due to poor dispersion of inorganic pigments, and the number of inorganic pigments that can be used in this method is severely limited. The disadvantage is that the optical properties of the resin molded product are limited to an extremely narrow range. On the other hand, other methods generally have drawbacks such as complicated steps, low productivity, and difficulty in adopting the method depending on the shape of the molded product. The present inventors have conducted intensive research on a method for manufacturing a resin molded product with a matte surface that can provide a wide range of optical properties using a simple method that overcomes the drawbacks of the prior art as described above. As a result, by stretch-molding a methacrylic resin material consisting of a continuous phase consisting of a polymer whose main constituent unit is methyl methacrylate and a dispersed phase consisting of a polymer of a specific (meth)acrylate ester, The present invention was completed by discovering that the material exhibits a beautiful matte surface. That is, the methacrylic resin molded product with a matte surface of the present invention has a continuous phase of 80 to 99.9% by weight.
It is composed of 0.1-20% by weight of the dispersed phase, and the continuous phase is
A polymer obtained from polymethyl methacrylate or a polymerizable unsaturated monomer containing 80% by weight or more of methyl methacrylate (hereinafter referred to as polymer [A])
The dispersed phase is formed by the following general formula [] (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents a hydrocarbon group having 2 or more carbon atoms or a derivative thereof.) 50% of the polymerizable unsaturated monomer
It is formed from a polymer obtained from a polymerizable unsaturated monomer mixture containing % by weight or more (hereinafter referred to as polymer [B]), and the refractive index n _A of polymer [A] and polymer [B] A light-diffusing methacrylic resin material whose refractive index _nB is _nB / _nA and satisfies 0.950≦ _nB / _nA <0.998 or 1.002< _nB / _nA ≦1.050 is heated by heating the resin material. It is obtained by stretch forming at a temperature higher than the deformation temperature. In addition, in the present invention, the refractive index is sodium D
Adopt the value measured at 20℃ against the line. The present invention will be further explained below. The light-diffusing methacrylic resin material (hereinafter simply referred to as resin material) used to produce the molded article of the present invention is composed of a continuous phase and a dispersed phase, and the polymer [A] forming the continuous phase There is a specific relationship between the refractive index of the polymer [B] that forms the dispersed phase, that is, the refractive index n _A of the polymer [A] and the refractive index n _B of the polymer [B].
There is a relationship in which the value of _nB / _nA is in the range of 0.950≦ _nB / _nA <0.998 or 1.002< _nB / _nA ≦1.050. If the value of n _B /n _A of the resin material is in the range of n _B /n _A <0.950 or 1.050 < n _B /n _A , the problem will be alleviated to some extent by the thickness reduction due to stretch forming. However, the resulting resin molded product has relatively strong reflection and low brightness, and the value of n _B /n _A is less than 0.998.
When n _B / n _A is in the range of <1.002, light diffusivity is imparted by the loss of gloss on the surface due to stretch molding, but the light diffusivity of the resin molded product may be insufficient depending on the stretching conditions, etc. Not. Therefore, in the present invention,
The value of n _B /n _A is appropriately selected depending on the light diffusivity required of the resin molded product. That is, when more emphasis is placed on brightness, the value of n _B /n _A is close to 1, whereas when more emphasis is placed on light diffusivity, the value of n B /n A is close to 1.
The value of n _B /n _A takes a value far from 1. When the background is viewed through the resin material, the background cannot be clearly recognized and begins to appear hazy when the value of β is about 2 to 3 degrees. Furthermore, as the value of β increases, the degree of haze in the background increases, but the total light transmittance generally decreases. The value of β required for a resin varies depending on its use. The disadvantage of conventional methacrylic resins that have been given light diffusing properties by adding light diffusing agents is that they require a relatively small β value, or even a relatively small β value. Even in cases where the above conditions are satisfied, the decrease in total light transmittance is significant. According to the present invention, it has become possible to obtain a sheet that has a high total light transmittance, has a diffusion effect β of 2° or more, and has a matte surface effect. The uniform dispersibility of the dispersed phase into the continuous phase in the resin material in the present invention is determined by the degree required by the use of the resin molded article. Generally, when observing transmitted light and reflected light with the naked eye, total light transmittance,
It is desirable that the light scattering performance be optically uniform to the extent that no local non-uniformity is observed. Further, there is a preferable range for the size of each dispersed particle of the dispersed phase when viewed microscopically. In other words, when the size of the dispersed particles is too small, the degree of matting of the resin molded product after stretch molding is often insufficient, which is undesirable.On the other hand, when the size of the dispersed particles is too large, the resin The surface of the molded product is difficult to achieve a beautiful matte state, which is undesirable. That is, the size of the dispersed particles is preferably a radius of 0.5 to 200 microns, more preferably 1 to 100 microns, in terms of a circular cross-sectional area. The resin material used in the present invention has a continuous phase of 80%
~99.9% by weight and a dispersed phase of 0.1-20% by weight. When the dispersed phase is less than 0.1% by weight, the light diffusion performance of the resulting resin is insufficient;
On the other hand, when the dispersed phase exceeds 20% by weight, the light diffusivity of the resulting resin is sufficient, but the total light transmittance of the resin decreases, and the weather resistance, solvent resistance, strength, and heat resistance decrease. tends to occur, which is generally undesirable. Within the above ranges, it is more preferred that the continuous phase is 90-99.5% by weight and the dispersed phase is 0.5-10% by weight. The continuous phase of the resin material in the present invention is formed from a polymer [A] obtained from polymethyl methacrylate alone or from a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate. Specific examples of other polymerizable unsaturated monomers that can be added to the polymerizable unsaturated monomer mixture and copolymerized with 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 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
(meth) of 2-hydroxypropyl acrylate, etc.
Examples include esters of acrylic acid and polyhydric alcohol, (meth)acrylic acid, styrene, and styrene derivatives. These polymerizable unsaturated monomers copolymerized with methyl methacrylate contain 20% of the polymerizable unsaturated monomer mixture.
It is added in an amount of % by weight or less. When the amount of methyl methacrylate added is less than 80% by weight, the strength, weather resistance, and heat resistance of the resulting resin tend to decrease,
Moreover, it is not preferable because it causes an increase in raw material cost. Among the polymerizable unsaturated monomers copolymerized with the above-mentioned methyl methacrylate, esters of (meth)acrylic acid and monovalent saturated alcohol are preferred. Furthermore, among these, methyl acrylate, (meth)
Ethyl acrylate, butyl (meth)acrylate,
Specific examples include 2-ethylhexyl (meth)acrylate. Furthermore, in a preferred embodiment of the present invention, 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] forming the continuous phase of the resin material in the present invention, polymethyl methacrylate and 90% by weight or more of methyl methacrylate, methyl acrylate, (meth)
Ethyl acrylate, butyl (meth)acrylate,
Examples include polymers obtained from a mixture with 10% by weight or less of a polymerizable unsaturated monomer selected from 2-ethylhexyl (meth)acrylate. Furthermore, the polymer [B] forming the dispersed phase of the resin material in the present invention satisfies the specific refractive index relationship defined within the scope of the present invention with the polymer [A] forming the continuous phase. , a polymer of at least one kind of polymerizable unsaturated monomer represented by the above general formula [], or a polymer containing at least one kind of polymerizable unsaturated monomer represented by the general formula [] in an amount of 50% by weight or more This is a polymer obtained from a mixture of polymerizable unsaturated monomers. Typical 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
(1.513) 2-Cyclohexylcyclohexyl methacrylate (1.519) 2-promoethyl methacrylate (1.543) Benzyl methacrylate (1.568) and isobutyl methacrylate, n-acrylate
Examples include hexyl, cyclohexyl acrylate, and 2-ethylhexyl methacrylate. 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 ratio of the refractive index with the polymer [A] forming the continuous phase is within a specific range, and The primary requirement is that the polymer [B] can be dispersed in a preferable state in the continuous phase, but from the viewpoint of manufacturing the resin molded article of the present invention, it is preferable that the polymer [B] is easy to handle. Preferably, it is in a glass state at room temperature. Therefore, as a preferred embodiment of obtaining the resin molded article of the present invention, t-butyl methacrylate, ethyl methacrylate, t-butyl methacrylate, ethyl methacrylate, From cyclohexyl methacrylate and benzyl methacrylate, select a base compound appropriately considering the desired refractive index, and use one of them, a combination of two or more of them, or one or more of them. General formula []
By polymerizing or copolymerizing in combination with other compounds represented by or other copolymerizable polymerizable unsaturated monomers, it is in a glass state at room temperature and has a desired refractive index. A polymer can be produced and used as the polymer [B] for forming the dispersed phase. Specifically, particularly preferred specific examples of the polymerizable unsaturated monomer represented by the general formula [] include t-butyl methacrylate (ratio of refractive index of the polymer to polymethyl methacrylate: 0.983, the same applies hereinafter), and ethyl methacrylate. (0.995), cyclohexyl methacrylate (1.010), benzyl methacrylate (1.051)
can be mentioned. The polymer [B] forming the dispersed phase of the resin material in the present invention is a polymer obtained by copolymerizing the polymerizable unsaturated monomer represented by the general formula [] with another polymerizable unsaturated monomer. 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, 1,3-butylene glycol di(meth)acrylate, trimethylolethane tri(meth)
Examples include esters of (meth)acrylic acid and polyhydric alcohols such as acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate. 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.
If the amount of the compound represented by the general formula [] is less than 50% by weight, even if the relationship of refractive index between the polymer [A] and the polymer [B] is within the range of the value of the present invention, It is difficult to control the state of dispersion of the coalesce [B] into the polymer [A] in a desirable state, and this is generally undesirable for the purpose of the present invention. Examples in which the amount of the compound 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 the polymer [A] and polymer [B], respectively, characterized above. However, depending on the conditions for manufacturing the resin molded article of the present invention, a very small amount of polymer [B] may exist in the continuous phase, or a very small amount of polymer [A] may exist in the dispersed phase. Alternatively, the polymer [A] may exist in a dispersed form in the dispersed phase, but the light-diffusing resin in such cases is not excluded from the scope of the present invention. The resin material used in the present invention is basically composed of two phases, a continuous phase and a dispersed phase as described above.
It may also contain various additives added to common methacrylic resins. Specific examples of these additives include dyes used for coloring, antioxidants, stabilizers such as ultraviolet absorbers, flame retardants, plasticizers, and release agents that make it easier to peel the resin from the mold. be able to. Alternatively, ordinary pigments such as titanium oxide, barium sulfate, calcium carbonate, aluminum hydroxide, etc., which are insoluble in both the continuous phase and the dispersed phase and form a third phase, or polystyrene, styrene-methyl methacrylate copolymer, etc. Also within the scope of the present invention are resins that have been given new light-diffusing performance by adding a conventional light-diffusing agent. Although the form of the resin material used in the present invention is not particularly limited, 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 m/m,
Furthermore, the thickness of 1 to 10 m/m is common. The method for producing the resin material used in the present invention is not particularly limited, but as a preferred specific method, a polymer [B] that forms a dispersed phase is produced in advance, and then the polymer [B] is mixed into a continuous phase polymer. [A]
Dissolved or dispersed in a polymerizable unsaturated monomer or a partial polymer thereof, a mixture of polymerizable unsaturated monomers, or a partial polymer to form a polymerizable composition, and then subjected this polymerizable composition to a polymerization step. A method for producing a resin material consisting of two phases, a continuous phase and a dispersed phase, can be mentioned. That is, the method for producing the resin material is a polymer of the polymerizable unsaturated monomer represented by the general formula [] or a polymerizable monomer containing 50% by weight or more of the polymerizable unsaturated monomer represented by the general formula []. Polymer obtained from unsaturated monomer mixture (hereinafter referred to as polymer [B])
Polymer [A] that forms a continuous phase in an amount of 0.1 to 20% by weight
It is dissolved or dispersed in methyl methacrylate, a polymerizable unsaturated monomer mixture containing 80% by weight or more of methyl methacrylate, or 80 to 99.9% by weight of a partial polymer thereof, and in the presence of a radical polymerization initiator. By polymerizing, usually in a mold, it is possible to produce a resin material composed of two phases: a continuous phase formed from the polymer [A] and a dispersed phase formed from the polymer [B]. Polymer [B] that forms a dispersed phase in the above method
There are no particular limitations on the method for producing the compound, and emulsion polymerization, solution polymerization, and bulk polymerization, which are usually carried out industrially, can also be employed, but in general, a method using suspension polymerization in an aqueous medium is preferred. When this suspension polymerization method is used, handling of the obtained polymer is easy, and the dissolution or dispersion of the polymer [B] into the polymerizable composition forming the continuous phase polymer [A] is comparatively easy. It has the advantage of being easy to use. The polymerizable composition to be converted into the polymer [A] forming the continuous phase of the resin material contains methyl methacrylate alone or 80% by weight of methyl methacrylate.
Any of the above-contained polymerizable unsaturated monomer mixtures and their partial polymers may be used. Generally, 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 the polymerizable unsaturated monomer is subjected to radical polymerization. A preferred example is a method in which a partially polymerized product is obtained by adding an initiator and heating the resulting composition to its boiling point. 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 degree of optical diffusivity of the resin obtained after polymerization is In order to have uniform brightness, it is preferable that the polymer [B] is uniformly dissolved in the polymerizable composition that becomes the polymer [A]. A radical polymerization initiator is added to a mixture in which polymer [B] is dissolved or dispersed in a polymerizable composition to become polymer [A], and the mixture is generally 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 to 150°C for polymerization. In particular, it is preferable to complete the polymerization by heating to 50 to 95°C in the first stage and then to 100 to 140°C in the second stage. Preferred specific examples of molds used during polymerization include two tempered glass plates whose peripheries are sealed with a soft gasket, and two opposing glass plates whose peripheries are sealed with a soft gasket in the same direction and at the same speed. An endless stainless steel belt with mirror polishing on one side can be used. Next, in order to obtain the resin molded article of the present invention, the resin material obtained as described above is stretch-molded at a temperature equal to or higher than the heat deformation temperature of the resin material. As a result, a resin molded article, which is the object of the present invention, can be obtained. In the present invention, the heat distortion temperature when stretch-molding is performed at a temperature higher than the heat distortion temperature in order to eliminate gloss on the surface of a resin material is the ASTM deflection temperature measured based on the test method of ASTM D-648-45T. shall be shown. The heating temperature for stretch-molding the resin material may be any temperature higher than the heat distortion temperature of the material, but it is usually preferable to stretch-form the resin material at a temperature higher than the heat distortion temperature +10°C. A specific method for stretch-molding a resin material is as follows:
Flat plate biaxial stretching or flat plate 1 by tenter method etc.
Examples include biaxial stretching on a curved surface by axial stretching, free-blow molding, push-up molding, vacuum forming, and the like. The gloss of the resulting resin molded product is determined by the stretching ratio, that is, {√( ₀ )-1}×100(%) (in the formula, d ₀ : thickness before stretching, d: thickness after stretching) from 0% to approximately
The degree of matting gradually becomes noticeable up to about 50%, and thereafter the degree of matting changes relatively slowly as the stretching ratio increases. On the other hand, the light diffusing ability inside the resin due to the inclusion of the dispersed phase monotonically decreases as the plate thickness decreases due to stretching. Therefore, the stretching ratio of the resin molded product is preferably selected appropriately depending on the degree of matteness and light diffusivity desired depending on the application. The present invention will be explained below based on specific examples.
In the examples, % means % by weight, and parts mean 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°, and the intrinsic viscosity of the polymer was measured in chloroform at 25°C. In addition, the total light transmittance of the resin is measured based on JIS K7105, and the maximum bending angle β indicates the degree of light diffusivity.
was measured by the following method. A tungsten lamp (2850〓) is lit on the optical table, and the incident illuminance of the sample is
Adjust the distance between the light source and the sample mounting table so that it is 10ft-cd. Place the sample on the mounting table, and place the luminance meter facing the sample. The brightness value (B ft-L) in the direction of 0° with respect to the optical axis is measured with a brightness meter. Next, measure the brightness value every 1 degree up to 5 degrees, and then measure the brightness value every 5 degrees up to 50 degrees. Gain G is calculated using the following formula. G=B ft-L/10ft-cd Take the bending angle on the horizontal axis and the gain on the vertical axis, draw a gain curve, read the angle where the gain is 33% of the 0° value from the diagram, and find it as the maximum bending angle β. do. The larger the value of the maximum bending angle β, the better the light diffusivity of the resin. Example 1 2 Proceeding in the same direction at the same speed according to the usual method
Methyl methacrylate partial polymer (polymer content
19%) 92.5 parts polycyclohexyl methacrylate (intrinsic viscosity number
0.013/g) 7.5 parts 2,2'-azobis(2,4-dimethylvaleronitrile) 0.045 parts sodium di-octylsulfosuccinate (removal agent) 0.001 parts was poured into a transparent composition and heated with hot water at 80°C. After passing through the zone for 28 minutes, the device passes through the far-infrared heater heating zone and slow cooling zone, which are heated to a maximum temperature of 135℃, for 14 minutes, allowing optical spots to be recognized with the naked eye at a thickness of 3 mm continuously from downstream. A light-diffusing resin plate with an unparalleled specular luster was obtained. This light-diffusing resin plate has a total light transmittance of 88%, a heat distortion temperature of 94.5°, a cross section of dispersed particles having a circular shape with an average radius of 7.1 microns, and n _B / n _A =
It was 1.008. The resin plate thus obtained was heated to 150℃ using a far-infrared heater.
The material was heated to 300°C and push-up molding was performed. By adjusting the conditions during molding, molded products with varying stretching ratios as shown in Table 1 were created. All of the molded products thus obtained had a beautiful matte surface. The relationship between the stretching ratio and glossiness, total light transmittance, and maximum bending angle β of the molded article was measured, and the results shown in Table 1 were obtained. This result also shows that the molded product has both high total light transmittance and relatively excellent light diffusivity.

[Table] Example 2 In the same manner as in Example 1, 98 parts of methyl methacrylate-ethyl acrylate copolymer (methyl methacrylate/ethyl acrylate, charge weight ratio 98/2, intrinsic viscosity number 0.026/g) was added. The continuous phase is polytertiarybutyl methacrylate (intrinsic viscosity
A light-diffusing resin plate with a thickness of 4 mm and having a specular gloss of 2 parts (0.015/g) as a dispersed phase was obtained. The total light transmittance of this resin plate was 87%, the heat distortion temperature was 95.1°C, the cross section of the dispersed particles was circular with an average radius of 3.6 microns, and n _B /n _A = 0.983. This light-diffusing resin plate was heated to 150°C in a hot air circulation oven, and then free blow molded into a hemispherical shape. The molded product thus obtained had a beautiful matte surface. Example 3 In the same manner as in Example 1, 97 parts of polymethyl methacrylate (intrinsic viscosity number 0.032/g) was used as a continuous phase, and cyclohexyl methacrylate-benzyl methacrylate copolymer (cyclohexyl methacrylate/benzyl methacrylate was charged). A light-diffusing resin plate having a mirror gloss and a thickness of 3 mm was obtained, having a weight ratio of 70/30 and 3 parts (intrinsic viscosity number of 0.017/g) as a dispersed phase. The total light transmittance of this resin plate is 87%, the heat distortion temperature is 98.4℃, and the cross section of the dispersed particles has an average radius of 4.3
It had a micron circular shape with n _B /n _A = 1.021. The light-diffusing resin plate thus obtained was heated to 140°C with a far-infrared heater and pushed up. By adjusting the conditions during molding, molded products with different stretching ratios as shown in Table 2 were created. All of the molded products thus obtained had a beautiful matte surface. The results shown in Table 2 were obtained when the relationship between the stretching ratio of the molded article, glossiness, total light transmittance, and maximum bending angle β was measured. This result shows that the molded product has both high total light transmittance and relatively excellent light diffusivity.

[Table] Example 4 According to a conventional method, a methyl methacrylate partial polymer (polymer content
6.5%) 95 parts tertiary butyl methacrylate-ethyl methacrylate copolymer 5 parts (tertiary butyl methacrylate/ethyl methacrylate charge weight ratio 60/40 intrinsic viscosity 0.033/g) 2,2'-Azobis(2 , 4-dimethylvaleronitrile 0.025 parts Tinuvin-P (UV absorber manufactured by Ciba Geigy)
0.01 part titanium oxide (“TITACR-550” manufactured by Sakai Chemical Industry Co., Ltd.)
A composition consisting of 0.9 parts (particle size: 0.3 to 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, resulting in a mirror surface with a thickness of 3 mm. A glossy white opaque plate with a thickness of 3 mm was obtained. The cross section of the dispersed particles made of tertiarybutyl methacrylate-ethyl methacrylate copolymer in this resin plate is an ellipse with an average major axis of 28 microns and an average minor axis of 20 microns, n _B / n _A = 0.987. It was hot. Further, the heat deformation temperature of this resin plate was 105.3°C. This resin plate was heated to 180°C in a hot air circulation oven and then free blow molded into a hemispherical shape. The molded product thus obtained had a beautiful matte surface. Comparative Example 1 The same procedure as in Example 4 was repeated except that the tertiary butyl methacrylate-ethyl methacrylate copolymer was removed from the composition to be injected to obtain a white opaque plate having a heat distortion temperature of 105.9°C.
This resin plate was heated to 180° C. in the same manner as in Example 4, and then free blow molded into a hemispherical shape. The surface of the molded product thus obtained maintained its specular gloss. In a cell composed of two sheets of tempered glass and a gasket, 98.25 parts of methyl methacrylate partial polymer, 1.75 parts of styrene-methyl methacrylate copolymer, and 0.045 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) Sodium di-octyl sulfosuccinate
0.001 part of the composition 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 obtain a resin plate. The maximum bending angle of this resin plate is 3°, and it functions as a diffuser plate, but the total light transmittance is as low as 78.2%, and the refractive index ratio between the continuous phase and the dispersed phase (n _B /n _A ) is
It was 1.053. Furthermore, this resin plate was heated and stretched in the same manner as in Example 1 to obtain the results shown in Table 3.

[Table] Comparative Example 3 Methyl methacrylate partial polymer as continuous phase
97.6 parts, cyclohexyl methacrylate-tertiary butyl methacrylate copolymer as the dispersed phase.
A transparent methacrylic resin plate with a thickness of 3 mm was obtained in the same manner as in Comparative Example 2, except that 2.4 parts were added. The n _B /n _A of this resin plate was 0.999. Further, when this resin plate was evaluated in the same manner as Comparative Example 2, the results shown in Table 4 were obtained.

【table】

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, and R ₂ represents a hydrocarbon group having 2 or more carbon atoms or a derivative thereof] At least one polymerizable unsaturated monomer represented by A polymer obtained from a polymerizable unsaturated monomer mixture containing 50% by weight or more of at least one polymerizable unsaturated monomer represented by the general formula [] , and the refractive index nA of the polymer [ _A ] and the refractive index _nB of the polymer [B] are expressed by the following relational expression: 0.950≦ _nB / _nA <0.998 or 1.002< _nB /n A methacrylic resin molded article having a matte surface obtained by stretch-molding a light-diffusing methacrylic resin material satisfying _A ≦1.050 at a temperature equal to or higher than the heat distortion temperature of the resin material. 2. Claim 1, wherein the size of each dispersed particle of the polymer [B] constituting the dispersed phase is 0.5 to 200 microns when converted to the radius of a sphere having the same cross-sectional area. A methacrylic resin molded product with the matte surface described.