CN1504773A - Synthetic resin molded product with excellent light transmission and diffusion properties - Google Patents

Abstract

Provided is a synthetic resin molded article which is easily removed from a mold, excellent in light transmission/diffusion while excellent repeated moldability is obtained. An irregularity form is formed on at least one side face of the light transmission/diffusion synthetic resin molding, and the tilt angle [theta] of the irregularity form is 20 to 60 degrees.

Description

Synthetic resin molded product with excellent light transmission and diffusion properties

technical field

The present invention relates to a synthetic resin molded product suitable for members having both properties of light transmission and diffusion, such as front panels of various displays, lighting covers and signboards, and light diffusion plates for backlights of liquid crystal displays.

Background technique

Various displays, lighting covers, signboards (signage boards), light diffusion plates for backlights of liquid crystal displays, etc., are required to be uniformly bright (high brightness) over the entire surface as a basic function. In recent years, displays of various types have been launched on the market, and the images thereof have become increasingly high-definition, high-brightness, and large-scale. The actual situation is that the illumination light sources used for these various displays, lighting covers, signboards, liquid crystal displays, etc. are increasingly advancing in high luminosity. These illuminating light sources are generally arranged on the back of the image display body in order to illuminate image information brightly. In this case, there is a problem that the light source image of the high-luminance illumination light source is directly reflected on the display image as it is. In order to solve this problem, methods such as using a material with high light-diffusing performance for the front panel itself, and attaching a light-scattering member (hereinafter abbreviated as a light-diffusing member) to the front of the illumination source are used.

Conventionally, light-diffusing members such as various displays, lighting covers, signboards, and backlights of liquid crystal displays have generally used synthetic resin materials in which inorganic or organic fine particles are dispersed in transparent synthetic resins. Using the difference in refractive index between these transparent synthetic resins and the dispersed fine particles, light rays are scattered by refraction and reflection at the interface between the base material resin and the dispersed fine particles, so that it has light diffusing properties.

Light-diffusing methacrylic synthetic resins obtained by dispersing inorganic or organic light-diffusing agents in methacrylic resins are used for lighting fixtures, glazing, signboards, various displays, rear projection screens, and Light diffusion plates for backlighting of liquid crystal displays such as LCD TVs, etc.

As a light-diffusing synthetic resin having high light-diffusing properties and high light-transmitting properties, for example, (a) making the transparent resin contain inorganic microparticles such as barium sulfate and calcium carbonate with an average particle diameter of 10 μm or less; powdered resin (see Patent Document 1); (b) disperse glass powder, quartz powder, calcium fluoride and other inorganic transparent substance powders in the transparent resin with an average particle size of 1-10 μm, or polystyrene, polymethacrylate , the resin of the organic transparent material powder of the fluoride of acrylate (referring to patent document 2); resin (see Patent Document 5); a resin in which polysiloxane, which is liquid at room temperature, is dispersed in a polymer mainly composed of methyl methacrylate (see Patent Document 6).

However, in the above-mentioned existing light-diffusing synthetic resins, when an inorganic substance powder is added as the light-diffusing powder, if the amount of powder added is reduced for the purpose of improving the total light transmittance, the haze value ( Haze value) is reduced, and the internal lighting is transparent and visible. On the other hand, if the added amount is increased for opacity to increase the haze value, there is a problem that the total light transmittance decreases.

In addition, when polysiloxane dispersed in a liquid state at room temperature is used as a light diffusing agent, it lacks compatibility and adhesion with the base material, and at the same time, the heat distortion temperature of the molded product is lowered, and it is heat-resistant near the light source. Insufficient in properties and bleeding depending on the blending amount, resulting in poor appearance of the product.

On the other hand, it has been proposed to form fine unevenness on the surface of the plate to improve light diffusivity (for example, see Patent Document 7). According to this invention, it is proposed to have a surface roughness shape with a ten-point average roughness (Rz) of 10-50 μm and an average peak spacing (Sm) of 30-70 μm in the surface roughness standard.

In order to manufacture a synthetic resin molded article with fine unevenness formed on the surface, the usual method is to use a mold in which the inverted shape of the unevenness is processed, and transfer it to the surface of the synthetic resin molded article. In this case, it is important in terms of industrial production to smoothly perform the process of releasing the shape-transferred synthetic resin molded article from the mold. However, in the above-mentioned predetermined shape, the surface of the molded glass is pulled out, or the molded product is pulled out from the side of the molded glass, etc., so that it is difficult to release the molded product, and the reproducibility of the concave and convex shape is not good, making industrial production difficult. At the same time, regarding optical performance, there is room for improvement in light diffusion performance in liquid crystal display applications and the like.

Therefore, the actual situation is that the appearance of a light-diffusing resin having high light diffusivity and high light transmittance without appearance problems is urgently desired, but practically it cannot fully satisfy the market demand.

(Patent Document 1)

Japanese Patent Laid-Open No. 60-139758 (Claims)

(Patent Document 2)

Japanese Patent Laid-Open No. 60-21662 (Claims)

(Patent Document 3)

Japanese Patent Laid-Open No. 60-184559 (Claims)

(Patent Document 4)

Japanese Patent Laid-Open No. 61-4762 (Claims)

(Patent Document 5)

Special Publication No. 5-16002 (Claims)

(Patent Document 6)

Japanese Patent Application Laid-Open No. 7-207101 (Claims)

(Patent Document 7)

Japanese Patent Application Publication No. 3-142401

Contents of the invention

The object of the present invention is to overcome the conventional problems and provide a synthetic resin molded product that has no appearance problem, is easy to release the molded product, has excellent repeatability, and has high light diffusivity and high light transmittance.

In order to obtain a synthetic resin molded article with excellent light transmission and diffusion properties, it is desirable that the light emitted from the point-shaped or rod-shaped light source arranged on the back surface be uniformly and brightly emitted to the surface side. In order to achieve this purpose, the inventors considered molding Ideal surface model for products. That is, focus on the following points: ① The light reflected from the surface of the molded product by the light incident on the molded product from the air layer, and the light reflected from the interface between the molded product and the air layer by the light emitted from the molded product to the air layer. Minimize as much as possible. In other words, as much light as possible from the light source arranged on the back is emitted to the opposite surface side, and (2) the diffusivity of the light from the light source is high.

Therefore, the concave-convex shape of the surface is specified by the ten-point average roughness (Rz) and the average peak spacing (Sm) (see Patent Document 7). Then, as shown in Fig. 1, the irregular shape of the surface is modeled, and as a parameter for specifying the shape, the average peak interval between peaks is denoted as P, the height of the irregularities, that is, the ten-point average roughness is expressed as Rz, and the unevenness The lengths of the flat parts of the peaks and valleys are denoted as a and b, and the inclination angle of the concavo-convex is denoted as θ. As a result of intensive research on these parameters, it was found that the inclination angle θ of the concavo-convex was greatly increased. Affects diffusion properties and total light transmission as well as release from molds.

Then, the present inventors found that the light-transmitting synthetic resin molded article having a specific concave-convex shape represented by introducing the inclination angle θ of the concave-convex as a new concept can solve the above-mentioned problems, and completed the present invention.

That is, the present invention relates to the above-mentioned light-transmitting and diffusing synthetic resin molded article, which is a light-transmitting and diffusing synthetic resin molded article having concavo-convex shapes formed on at least one surface, and the inclination angle θ of the concavo-convex shapes is 20° to 60°.

Furthermore, the present invention relates to the above-mentioned light-transmitting and diffusing synthetic resin molded article, wherein the average peak interval P of the concavo-convex shape is 5 μm to 50 μm, and the ten-point average roughness Rz in the surface roughness standard is 3 μm to 15 μm.

Also, the present invention relates to the above-mentioned light-transmitting and diffusing synthetic resin molded article having Rz/P=0.2-0.7.

Furthermore, the present invention relates to the above-mentioned light-transmitting and diffusing synthetic resin molded article, which is characterized in that it is obtained by polymerizing a monomer mixture containing 80-99.5% by mass of methyl methacrylate The main unsaturated monomer, and 20-0.5% by mass of a liquid reactive polysiloxane compound at normal temperature.

Furthermore, the present invention relates to the aforementioned light-transmitting and diffusing synthetic resin molded article, wherein the unsaturated monomer mainly composed of methyl methacrylate contains a monofunctional unsaturated monomer mainly composed of methyl methacrylate. 80-99.9% by mass of an unsaturated monomer, and 20-0.1% by mass of a crosslinkable vinyl monomer having two or more vinyl groups in the molecule.

Furthermore, the present invention relates to the above-mentioned light-transmitting and diffusing synthetic resin molded article, which further contains 0.01-0.05 parts by mass of a fluorescent dye selected from naphthalimide and perylene dye with respect to 100 parts by mass of the monomer mixture.

Further, the present invention relates to the above-mentioned light-transmitting and diffusing synthetic resin molded article, wherein cured particles of the reactive polysiloxane compound are dispersed with a primary particle size of 0.05-1 μm and a secondary particle size of 1-20 μm.

Furthermore, this invention relates to the light-diffusion plate containing the said light-transmitting diffusible synthetic resin molded article.

Moreover, this invention relates to the said light-diffusion plate for liquid crystal displays.

Furthermore, the present invention relates to a method for producing the above-mentioned light-transmitting and diffusing synthetic resin molded article, which is cast-polymerized using two glass plates as templates.

The surface shape of the light-transmitting and diffusing synthetic resin molded article of the present invention is defined by the concave-convex inclination angle θ, which is a new concept. The surface shape that satisfies this is compared with the past, and the size is finer. The performance balance is well improved, and the molding (release) is also easy, and the product is excellent in industrial productivity.

Even if P and RZ are the same, the inclination angle θ varies with the dimensions of a and b, and when θ is large, the diffusion performance increases while the total light transmittance decreases.

In addition, in conventional molded products, Rz is 10 μm to 50 μm. Since the height Rz of the unevenness is large, the surface of the molded glass is pulled out when the mold is released from the mold, or the molded product is pulled out by the side of the molded glass, etc. , Difficult demoulding of molded products. On the other hand, a preferred aspect of the light-transmitting diffusible synthetic resin molded article of the present invention having the above-mentioned inclination angle is the following shape: Rz is small, 3 μm-15 μm, and the mold release property is greatly improved. On the other hand, the P is fine-pitched to 5 μm to 50 μm, thereby preventing the inclination angle θ from becoming small. Therefore, although the light diffusing performance and the light transmittance are maintained, the releasability is excellent.

Also, in the light-transmitting and diffusing synthetic resin of the present invention, when using a methacrylic resin in which a reactive polysiloxane compound is mixed with an unsaturated monomer of methyl methacrylate and polymerized as a preferred embodiment, Molded products have excellent heat resistance, no bleeding, and excellent appearance.

Description of drawings

Fig. 1 is a diagram showing the surface irregularities of a synthetic resin molded sheet.

Detailed ways

The present invention will be described in detail below.

The synthetic resin molded article having excellent light transmission and diffusibility of the present invention has a roughness shape on the surface, and the inclination angle θ of the roughness is 20 degrees to 60 degrees. In addition, in order to satisfy the above θ and improve light transmission and diffusivity in a balanced manner, the height Rz is preferably 3 μm-15 μm, the pitch P is 5 μm-50 μm, and the ratio Rz/P of Rz to P is 0.2-0.7.

In order to maintain good light-diffusing performance, and to avoid damage to the mold and shape of the molded product, such as the surface of the mold glass being pulled out, the molded product being pulled out from the side of the mold glass, etc., when the synthetic resin molded product is taken out from the mold. To damage or greatly damage the quality, it is preferable that the height Rz is 5 μm-10 μm, P is 5 μm-30 μm, Rz/P is 0.25-0.6, and the inclination angle θ is 30-55 degrees.

The concavo-convex shapes that are present in many cases on the surface of the synthetic resin molded article of the present invention can be measured with devices such as optical microscopes, electron microscopes, magnifying projectors, stylus surface roughness measuring devices, and laser microscopes.

In addition, in the measurement of the average interval (Sm) of the unevenness by the conventional stylus-type surface roughness measuring device, when the shape is miniaturized, the number of damaged peaks and valleys increases, and the measurement becomes smaller than that obtained by microscope magnified observation. The value of the actual size is large; the discrete value of the value is extremely large and lacks reliability, so it may not be able to express the actual concave-convex size, and the above-mentioned problems exist. Therefore, in the synthetic resin molded article of the present invention, it is preferable to measure the average peak interval P and the inclination angle θ by observation with a microscope or the like.

The height of the unevenness, that is, the ten-point average roughness (Rz) is a value measured in accordance with the surface roughness standard JISB0601-1994.

In the synthetic resin molded article excellent in light transmission and diffusivity of the present invention, it is necessary to form the above-mentioned surface unevenness on at least one surface. When it is necessary to improve the light diffusion performance and reduce the warpage of the molded product due to the temperature difference between the front and back, it is better to form the surface unevenness on both the front and back sides.

As the synthetic resin material used in the present invention, a material with high light transmittance and excellent see-through is preferable. For example, methacrylic resin, MS resin, polycarbonate resin, polystyrene resin, polyethylene terephthalate resin, vinyl chloride resin etc. are mentioned. Among them, a methacrylic resin having a high light transmittance and little coloration due to ultraviolet rays is particularly preferable.

The so-called methacrylic resin is a polymer mainly composed of methyl methacrylate units, especially methyl methacrylate homopolymer, or methyl methacrylate and methyl acrylate, ethyl acrylate, n-propyl acrylate, etc. ester, isopropyl acrylate, n-butyl acrylate, acrylonitrile, maleic anhydride, styrene or α-methylstyrene, and the copolymer of methyl methacrylate homopolymer and the above-mentioned copolymer mixture etc.

The above-mentioned monomer is added to a polymerization initiator and molded into a plate shape. As the polymerization initiator, radical polymerization initiators such as oil-soluble organic peroxides and azo compounds can be used.

The compounding quantity of these polymerization initiators is preferably about 0.03-0.3 mass % with respect to a base material.

In addition, by mixing a crosslinking agent and casting polymerization, a methacrylic resin plate with a high deflection temperature under load can be obtained, and it can be used in a high-temperature environment and in applications where a temperature difference between the surface and the inside occurs, and the warpage of the plate is small. Synthetic resin board. This is an ideal characteristic for components such as various displays, lighting fixtures, and signboards.

Examples of the crosslinking agent herein include monomers having at least two (meth)acryloyl groups in the molecule and 10 or less atoms between the above-mentioned (meth)acryloyl groups. Monomers represented by the following formulas (1) to (3) are preferred.

MA-O-(CH ₂ ) _n -O-MA…(1)

(where n is an integer of 3-6, and MA represents a methacryloyl group.)

[chemical formula 1]

(Wherein, R ₁ represents H, CH ₃ , C ₂ H ₅ or CH ₂ OH group, R ₂ represents H, CH ₃ ,

[chemical formula 2]

(R ₄ represents H, CH ₃ group), or CH ₂ OH group, R ₃ represents H, CH ₃ group, R ₁ , R ₂ and R ₃ are not hydrogen at the same time, (M)A represents methacryloyl or acrylic Acyl. )

(M)AO-(-CH ₂ CH ₂ O-) _n -(M)A... (3)

(where n is 1 or 2.)

The compounding amount of the crosslinking agent, if considering the heat resistance of the finally obtained resin molded product and the deterioration of the weather resistance (yellowing, etc.) caused by the side chain with uncrosslinked double bonds in the resin molded product, etc. It is preferably 2 to 40 parts by weight, more preferably 2.5 to 30 parts by weight with respect to 100 parts by weight of the aforementioned synthetic resin raw material.

It is possible to disperse inorganic or organic fine particles as the light diffusing member in each synthetic resin. It is preferable to use transparent fine particles having a refractive index different from that of the synthetic resin material used as the substrate, for example, silicone resin, inorganic glass, acrylic resin, styrene resin, titanium oxide, silicon oxide, fluororesin, aluminum hydroxide, Microparticles such as barium sulfate and calcium carbonate.

Various particle shapes and particle sizes can be used as the diffusing member. They can be used singly or in combination.

The amount of the diffusing member can be determined in consideration of the balance between light transmittance and diffusing performance.

In the synthetic resin molded article of the present invention, the light diffusing member can also be dispersed in the synthetic resin as described above, but the reactive polysiloxane compound is dispersed and polymerized in an unsaturated monomer mainly composed of methyl methacrylate. The synthetic methacrylic resin can obtain high light diffusivity and high light transmittance, and is ideal as a material.

Specifically, it is formed by polymerizing a monomer mixture composed of 80-99.5% by mass of unsaturated monomer mainly composed of methyl methacrylate and 20-0.5% by mass of reactive polysiloxane compound which is liquid at normal temperature Synthetic resins are preferred.

The so-called unsaturated monomer mainly composed of methyl methacrylate means: relative to the total amount of unsaturated monomers, methyl methacrylate is contained in an amount of 50% by mass or more, preferably in an amount of 60% by mass or more, more preferably in an amount of 80% by mass. An unsaturated monomer or a mixture of unsaturated monomers may contain other unsaturated monomers in mass % or more.

Other unsaturated monomers that can be used in combination with methyl methacrylate are not particularly limited as long as they can be copolymerized with methyl methacrylate. Specific examples of such monomers include monohydric alcohols having 1 to 18 carbon atoms in one molecule, esters of monohydric phenol and acrylic acid, and monohydric alcohols having 2 to 18 carbon atoms in one molecule. Or ester of monohydric phenol and methacrylic acid, monoester of dihydric alcohol with 2-4 carbon atoms in one molecule and acrylic acid or methacrylic acid, acrylic acid, methacrylic acid, acrylonitrile, acrylamide, styrene , α-methylstyrene, vinyl acetate, vinyl chloride, vinylidene chloride, vinylidene fluoride, ethylene, maleic anhydride, maleic acid, fumaric acid, glycidyl (meth)acrylate and other monofunctional non- Saturated monomers and the like, but not limited to these. In addition, the other unsaturated monomer used together with methyl methacrylate may be a mixture of 2 or more types.

Moreover, it is preferable to use the crosslinkable vinyl monomer which has 2 or more vinyl groups in a molecule|numerator as another unsaturated monomer used together with methyl methacrylate. Specific examples of the crosslinkable vinyl monomer include (meth)acrylic acid, ethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, neopentyl glycol, 1,6- Hexylene glycol, tetramethylolmethane, dimethylolethane, trimethylolethane, dimethylolpropane, trimethylolpropane, pentaerythritol, dipentaerythritol and other polyol polyesters, (methyl ) allyl acrylate, divinylbenzene, triallyl isocyanurate and other polyfunctional unsaturated monomers; etc., but not limited to these. Furthermore, the so-called crosslinkable vinyl monomer having two or more vinyl groups in the molecule may constitute a mixture of two or more kinds. Particularly preferred are ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, and the like.

The unsaturated monomer mainly composed of methyl methacrylate is preferably composed of 80-99.9 mass % of monofunctional unsaturated monomer mainly composed of methyl methacrylate and It is composed of 20-0.1% by mass of a cross-linkable vinyl monomer having two or more vinyl groups in the molecule. The crosslinkable vinyl monomer is preferably 15-1% by mass, more preferably 12-2% by mass.

The reactive, liquid polysiloxane compound used in the present invention is preferably a compound composed of at least one compound represented by the following structural formula. In addition, in the present invention, the term that the polysiloxane compound is liquid at normal temperature means a state in which the viscosity at 25°C is 1 to 20000 mm ² /s.

[chemical formula 3]

In the formula, the organic group refers to -RNHR', amino group, -RCOOH, -ROH, -RSH, epoxy group (including epoxy propyl group, epoxy cycloalkyl group), polyether group, etc.; R and R' refer to the alkyl group or an alkylene group; m and n refer to integers.

[chemical formula 4]

In the formula, the organic group refers to epoxy group (including glycidyl group, epoxy cycloalkyl group), -RCOOH, -ROH, CH ₂ ═C(CH ₃ )COOR-, -RC ₆ H ₅ OH, amino, poly Ether group, etc.; R refers to an alkylene group; n refers to an integer.

[chemical formula 5]

In the formula, the organic group refers to epoxy group (including glycidyl group, epoxy cycloalkyl group), -RCOOH, -ROH, CH ₂ ═C(CH ₃ )COOR-, -RC ₆ H ₅ OH, amino, poly Ether group, etc.; R refers to an alkylene group; n refers to an integer.

[chemical formula 6]

In the formula, the organic group refers to -ROH, -R(OH) ₂ , epoxy group (including epoxypropyl group, epoxycycloalkyl group), CH ₂ ═C(CH ₃ )COOR-, etc.; R=alkyl or Alkylene; n refers to an integer.

[chemical formula 7]

In the formula, organic group refers to amino group, alkoxy group, etc.; R refers to alkyl group; m and n refer to integers.

Among these, it is particularly preferable to use a reactive polysiloxane compound having a double-end type structure in which two chemical formulas 5 are bonded from the viewpoint of easy generation of secondary particles due to phase separation.

The amount of the reactive polysiloxane compound is based on the monomer mixture composed of an unsaturated monomer mainly composed of methyl methacrylate and the reactive polysiloxane compound, if good light diffusivity is considered and cost, it is preferably 0.5-20% by mass, more preferably 1-10% by mass.

In addition, the reactive polysiloxane compound in such a light-transmitting and diffusing synthetic resin is preferably dispersed with a particle size of 0.05 to 20 μm during polymerization so that the red color of the transmitted light is not strong and does not cause transmission. .

The light-transmitting and diffusing synthetic resin obtained by mixing and polymerizing the above-mentioned reactive polysiloxane compound is characterized in that during the polymerization of the monomer mixture, the reactive polysiloxane compound formed is cured by phase separation. Particles, using their tiny particles, diffuse light. That is, it has the following effect: by combining the curing reaction of the reactive polysiloxane compound and the polymerization reaction of the unsaturated monomer including the unsaturated monomer, preferably the crosslinkable vinyl monomer, the polysiloxane is formed by phase separation during the polymerization. A microparticle-level secondary particle that is an aggregate of fine particles having a primary particle diameter of the submicron-level.

In such a light-transmitting and diffusing synthetic resin, the cured primary particles of the reactive polysiloxane aggregate to form secondary particles. In the light-transmitting diffusing synthetic resin, all the primary particles are preferably surrounded by secondary particles, but if there is a small amount, the primary particles may be individually dispersed. The secondary particles are aggregated and aggregated to such an extent that individual primary particles can be distinguished, and are not perfectly circular, but have a substantially circular or oblong cross-sectional shape with unevenness. The primary particle size is preferably 0.05-1 μm, more preferably 0.08-0.8 μm. The particle size of the secondary particles is preferably 1-20 μm, more preferably 1-10 μm.

In addition, by adjusting the compounding amount of the reactive polysiloxane compound, the type and amount of the crosslinkable vinyl monomer having two or more vinyl groups in the molecule, the polymerization conditions, the polymerization speed, etc., the phase separation process can be controlled. The particle diameter of the obtained reactive polysiloxane microparticles can be adjusted, and it is possible to disperse the microparticles with different particle diameters at the same time as the polymerization at a lower cost than the previously prepared microparticles.

Furthermore, by blending a cross-linkable vinyl monomer, the thermal rigidity of the light-diffusing plate made of the obtained light-transmitting diffusible synthetic resin can be increased, and warping due to temperature difference between the front and back and moisture absorption can be prevented.

The method of polymerizing and curing the monomer mixture composed of the above-mentioned reactive polysiloxane compound and the unsaturated monomer mainly composed of methyl methacrylate is not particularly limited, for example, free radical polymerization initiator A method of heating in the presence or absence of a radical polymerization initiator, a method using a so-called redox system composed of a radical polymerization initiator and an accelerator, and the like.

The method for producing the synthetic resin molded article excellent in light transmission and diffusibility of the present invention is not particularly limited, but cast polymerization molding (cast polymerization molding), press molding, extrusion molding, injection molding, etc. can be used. In these methods, the concave-convex shape of the present invention is transferred from a mold in which the concave-convex shape is formed in advance, thereby forming the concave-convex shape on the surface of the synthetic resin molded article. In terms of the degree of freedom in the dimensional reproducibility of the concave-convex shape and the function-imparting properties such as heat resistance by adding a cross-linking agent, a glass plate is used as a mold, and the resin raw material is injected into the mold, polymerized, and transferred. After cooling, the The cast polymerization molding method (cast polymerization) of mold release is most preferable.

The material of the mold for forming the concavo-convex shape used in the present invention is not particularly limited, and examples thereof include inorganic glass, stainless steel, and chrome-plated metal.

The method for forming the concave-convex shape on the mold is not particularly limited, and methods such as sand blasting, chemical etching, and a combination of sand blasting and chemical etching can be used.

The above-mentioned concavo-convex shape is obtained by mixing chemical solutions such as hydrofluoric acid, ammonium fluoride, sulfuric acid, and hydrochloric acid in various combinations, and changing the predetermined temperature, immersion time, and number of immersion times. In addition, care must be taken to obtain uneven shapes depending on the composition of the glass plate used.

In addition, in the polymerization reaction of the methacrylic resin polymerized with the above-mentioned reactive polysiloxane compound, in order to make the particle size of the primary particle and the particle size of the secondary particle fall within an appropriate range, the monomer is allowed to stand still in the mold. A casting polymerization method in which the mixture is polymerized is preferable, and specifically, a casting polymerization method in which a plate is molded simultaneously with polymerization between two templates is preferable. There are no particular limitations on the material of the mold used in cast polymerization, and any material such as metal, glass, ceramics, or resin can be used. Wherein, the formwork that will be made of the above-mentioned two glass plates that have the opposite surface shape of the surface shape of the light diffusion plate of the present invention is assembled by making the mold faces face each other through spacers such as vinyl chloride cylinders, The method of performing cast polymerization while maintaining the mold surface horizontally or vertically is preferable because the effect of the present invention can be appropriately exhibited.

In addition, UV absorbers, heat stabilizers, antioxidants, fluorescent whitening agents, antistatic agents, flame retardants, plasticizers, fluorescent dyes and other pigments, reinforcing agents, modifiers, mold release agents, etc. Various additives such as stabilizers and antibacterial agents. These additives should be used to greatly reduce the light transmittance of synthetic resin moldings, or to determine the amount of addition without greatly increasing the haze value.

The shape of the synthetic resin molded article of the present invention is not particularly limited, but a flat plate shape is preferably used. The thickness of the molded product is also not particularly limited, and good performance can be exhibited from a thin product of 0.1 mm to 5 mm to a thick product of about 60 mm.

Among them, the fluorescent dye selected from naphthalimide or perylene dye is blended in an amount of 0.01 to 0.05 parts by mass based on 100 parts by mass of the monomer mixture to obtain excellent light resistance. In addition, as a characteristic of this fluorescent dye, it converts near-ultraviolet light incident from a light source to the long-wavelength side, increases visible light, and improves visibility. It is possible to obtain more excellent high transmittance and high diffusivity of permanent synthetic resin.

Furthermore, in the synthetic resin of the present invention, relative to the mass of the light-transmitting diffusible synthetic resin, 5-30 mass % of the outermost layer composed of a methyl methacrylate polymer is contained, and the inner layer is composed of Polymer particles having a multilayer structure of at least one rubbery polymer layer composed of acrylic rubber or the like are also possible. Accordingly, the impact resistance and shape retention at high temperature are more excellent, and the occurrence of appearance defects such as warping can be prevented even after repeated use at high temperature and low temperature by turning off the light source or the like.

The light-transmitting and diffusing synthetic resin of the present invention can be preferably used in lighting fixtures, glazing, signboards, various displays, rear projection screens, and liquid crystal televisions due to its high light transmittance and high light diffusivity. Light diffusion plates for backlight sources of liquid crystal displays, etc. In particular, for liquid crystal displays such as large-screen TVs, in order to make the light source into a direct-type backlight and install a large number of linear light sources close to the light diffusion plate, it is required that the shape of the light source is not transparent and can be seen. Excellent light diffusivity , heat resistance, and it is necessary to faithfully reproduce the color tone of the image and the color temperature of the light source, so the characteristics of the present invention can be more effectively exerted.

Example

The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

Evaluations in Examples were performed by the following methods.

(1) Surface shape

The average height Rz of the shape model (FIG. 1) was measured in accordance with JIS B0601-1994 using a universal surface shape measuring device SE-3C manufactured by Kosaka Laboratories Co., Ltd. The interval (pitch) P between the peaks was measured using an optical microscope manufactured by Nippon Kogyo Co., Ltd. and an image analysis optical microscope manufactured by Keyence Co., Ltd. Microfield VH-8000. The inclination angle θ of the concavo-convex was measured with an ultra-deep shape microscope (laser microscope) VF-7500 manufactured by Keyence Co., Ltd.

(2) Evaluation of release properties

After the synthetic resin molded plate molded by casting polymerization was cooled to room temperature, a wedge was driven into the gap between two casting molds whose uneven surfaces faced each other, and the peeling of the molded plate from the mold was observed.

The case where a wedge is driven into the 4 corners once and the case is completely peeled off is marked as ○, and the case where the mold is hit and the wedge is driven many times and finally peeled off is marked as △, a part of the surface of the forming plate is pulled out by the side of the mold, on the contrary, The case where the glass mold was pulled out from the side of the molding plate was marked as x.

(3) Optical properties

The quality of the optical properties is evaluated by the total light transmittance τt, the diffusion coefficient D, and the evaluation of the light image from the perspective of the application field of the present invention.

①Total light transmittance τt

The measurement was carried out in accordance with JIS K7136; 2000 (ISO14782; 1999) using He-zume-ta HM-150 manufactured by Murakami Color Technology Research Institute Co., Ltd.

The larger the Tt, the brighter it is, and it is a preferable form.

② Diffusion coefficient D

Using the ゴニリオフオトメ-タ-GP-1R type manufactured by Murakami Color Technology Research Institute Co., Ltd., light is irradiated from the normal direction to the surface of the sample plate (50mm×50mm), and the light receiver arranged on the opposite side of the light source is opposite to the sample. The normal line can be varied from 0° to 90°, and the intensity (I _θ ) of the transmitted light at the respective angles from the normal line can be measured. The intensities at angles of 5°, 20°, and 70° are denoted as I5°, I20°, and I70°, respectively. Then, B _θ (B _θ =I _θ /COSθ) was obtained for each angle, and the diffusion coefficient D was obtained from the following formula.

D＝(B ₇₀ +B ₂₀ )/2×B ₅ (Formula)

The larger the diffusion coefficient D is, the more excellent the diffusibility of light is.

③ light source image (lamp image)

The light source image evaluation was carried out by the following two tests: Test 1 in which no diffusing fine particles were blended into the base resin and Test 2 in which diffusing fine particles were blended in the base resin.

Test 1: The test sample was placed 50mm away from the 40W fluorescent lamp. Pass the test sample at a distance of about 30 cm from the test sample, and observe the image of the fluorescent lamp with naked eyes. When the image of the fluorescent lamp was blurred and unclear, it was rated as ◯; if the image of the fluorescent lamp was discernible, it was rated as ×. Test 1 is a test method suitable for evaluation of general-purpose light-diffusing panels such as lighting covers and signboards.

Test 2: A test sample was placed in contact with a 200W incandescent light bulb (the cover glass was transparent). Pass the test sample at a distance of about 30 cm from the test sample, and observe the filament image of the incandescent light bulb with the naked eye. The case where the filament image cannot be seen is marked as ◎; the case where the filament image can be discerned although the filament image is blurred is marked as ○; the case where the filament image can always be discerned is marked as △ or ×. Test 2 is suitable for evaluation of a light-diffusing plate for a backlight of a liquid crystal display, and is a test method with stricter conditions than Test 1.

(4) Observation by electron microscope

After ion sputtering, the cut surface of the light diffusion plate was observed and photographed using a scanning electron microscope JSM6300F manufactured by JEOL Ltd.

(5) Light fastness test

The color change ΔE before and after the 100-hour xenon fading test was determined using a Ci65 weather-meter made by ATLAS and SM-7 of the Suga test mechanism, using a 2-degree field of view, a C light source, and a transmission method.

(6) Heat distortion temperature

According to JIS K7112, it is measured by deflection temperature under load without annealing.

Example 1 (embodiment)

(1) Production of molded glass

A glass plate with a thickness of 10 mm was dipped in a fluorine-based acid etchant [Glass Matting Agent Lerite SX-20 manufactured by SEPPIC (France)] for 60 seconds at room temperature and washed with water to produce a mold glass having a desired surface shape.

(2) Face them so that the surface formed with the desired surface shape is on the inside, sandwich a soft vinyl chloride resin gasket (gasket) so that the gap is 2 mm, and assemble it into a glass cell.

Then, 100 parts by weight of methyl methacrylate partial polymer, 0.1 part by weight of 2,2'-azobisisobutyronitrile, 0.03 parts by weight of 2-(2'-hydroxy-5-methylphenyl)benzotriazole parts by weight, 0.1 parts by weight of stearic acid. The slurry was poured into a glass tank, heated and polymerized in 60°C warm water for 2 hours, and heated in a 120°C furnace for 2 hours. After cooling, the glass tank is peeled off to obtain a synthetic resin molded board. Table 1 shows the evaluation results of releasability, surface shape, optical properties, and material properties during plate production.

Since this synthetic resin board eliminates the light source image of fluorescent lamps and emits bright white light as a whole, it is also extremely useful as a material for backlit illuminated signboards, as well as a display for craftsmanship and a display for shielding.

Example 2 (embodiment)

Using the molded glass used in Example 1, face it so that the surface formed with the desired surface shape is on the inside, sandwich a soft vinyl chloride resin gasket so that the gap is 2 mm, and assemble it into a glass cell .

Then, 5 parts by weight of commercially available silicone beads were mixed with 20 parts by weight of methyl methacrylate, and mixed and stirred for 15 minutes. Thereafter, 68.5 parts by weight of methyl methacrylate partial polymer, 7.0 parts by weight of neopentyl glycol dimethacrylate, and 0.03 parts by weight of 2-(2'-hydroxy-5-methylphenyl)benzotriazole were added. 0.01 parts by weight of stearic acid, 0.1 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) and 1,1-bis(tert-butyl peroxide)-3,3,5 - 0.1 part by weight of trimethylcyclohexane, stirred for 30 minutes. The slurry was poured into a glass tank, heated and polymerized in 60°C warm water for 2 hours, and heated in a 120°C furnace for 2 hours. After cooling, the glass tank is peeled off to obtain a synthetic resin molded board. Table 1 shows the evaluation results of releasability, surface shape, optical properties, and material properties during plate production.

This synthetic resin plate not only almost completely eliminates the backlight image of the fluorescent lamp, but also maintains a high total light transmittance. It is useful as a light diffuser for high-performance signboards and backlights for various displays.

Example 3-Example 8 (embodiment)

Change the type of fluorine-based acid etching solution, the time of immersion (10-300 seconds) and the number of times of immersion (1-3 times) to produce model glass with various surface shapes on a 10mm thick glass plate. The glass was opposed so that the surface forming the surface shape was on the inside, and a sealing gasket made of a soft vinyl chloride resin was sandwiched so that the gap was 2 mm, and a glass cell was assembled. The same slurry as in Example 2 was poured into this glass cell, and a synthetic resin molded plate was obtained in the same manner as in Example 1. Table 1 shows the evaluation results of releasability, surface shape, optical properties, and material properties during plate production.

Example 9 (embodiment)

Instead of silicone beads, 2 parts by weight of a reactive polysiloxane compound [X-24-4044 manufactured by Shin-Etsu Chemical Co., Ltd. (821 mm ² /s, acryloyl equivalent weight 3600 g/mol) having a structure represented by Chemical Formula 5 was blended. ], and obtained a synthetic resin plate with a thickness of 2 mm in the same manner as in Example 2. The evaluation results are shown in Table 1.

Example 10 (comparative example)

Two smooth glass plates with a thickness of 10 mm were opposed to each other, and a gasket made of a soft vinyl chloride resin was sandwiched so that the gap was 2 mm, and a glass cell was assembled. The same slurry as in Example 1 was poured into this glass cell, and a synthetic resin molded plate was obtained in the same manner as in Example 1.

Table 1 shows the evaluation results of releasability, surface shape, optical properties, and material properties during plate production.

Example 11 (comparative example)

Two smooth glass plates with a thickness of 10 mm were opposed to each other, and a gasket made of a soft vinyl chloride resin was sandwiched so that the gap was 2 mm, and a glass cell was assembled. The same slurry as in Example 2 was poured into this glass cell, and a synthetic resin molded plate was obtained in the same manner as in Example 2.

Table 1 shows the evaluation results of releasability, surface shape, optical properties, and material properties during plate production.

Example 12-15 (comparative example)

The type of fluorine-based acid etching solution, the time of immersion, and the number of times of immersion were changed by changing the type of fluorine-based acid etching solution on a 10mm thick glass plate to produce molded glass with various surface shapes. The glass was opposed so that the surface forming the surface shape was on the inside, and a sealing gasket made of a soft vinyl chloride resin was sandwiched so that the gap was 2 mm, and a glass cell was assembled. The same slurry as in Example 2 was poured into this glass cell, and a synthetic resin molded plate was obtained in the same manner as in Example 1. Table 1 shows the evaluation results of releasability, surface shape, optical properties, and material properties during plate production.

Table 1 Surface bump shape Mold release optical properties physical properties P(μm) Rz(μm) Rz/P θ (degrees) Total light transmittance τt(%) Diffusion coefficient D light source image Load deflection temperature (°C) Example 1 (embodiment) 10 5 0.5 50 ○ 80 0.28 ○ 110 Example 2 (embodiment) 10 5 0.5 50 ○ 51 0.98 ◎(Test 1) 117 Example 3 (embodiment) 15 10 0.67 55 ○-△ 49 0.982 ◎(Test 2) 117 Example 4 (embodiment) 20 10 0.5 50 ○ 50 0.98 ◎(Test 2) 117 Example 5 (embodiment) 15 5 0.33 40 ○ 51 0.98 ◎(Test 2) 117 Example 6 (embodiment) 20 5 0.25 30 ○ 52 0.975 ◎(Test 2) 117 Example 7 (embodiment) 40 12 0.3 30 ○ 52 0.96 ○(Test 2) 117 Example 8 (embodiment) 45 12 0.26 28 ○ 52 0.957 ○(Test 2) 117 Example 9 (embodiment) 10 5 0.5 50 ○ 56 0.80 ○(Test 1) 116 Example 10 (comparative example) 900 0.16 0.0002 0.25 ○ 92 0.01 ×(Test 1) 110 Example 11 (comparative example) 600 0.2 0.0003 0.3 ○ 51 0.94 ×(Test 2) 117 Example 12 (comparative example) 50 2 0.04 4.5 ○ 51 0.945 △(Test 2) 117 Example 13 (comparative example) 100 8 0.08 9 ○ 51 0.95 △(Test 2) 117 Example 14 (comparative example) 20 15 0.75 59 x Can't measure Can't measure Not determined 117 Example 15 (comparative example) 50 30 0.6 53 x Can't measure Can't measure Not determined 117

The synthetic resin molded sheet of the present invention in Example 1 has a high total light transmittance and maintains the overall brightness. Compared with Example 10 (comparative example), the diffusion coefficient is also high, and the image of the fluorescent lamp can be eliminated, and the image of the light source is also good.

The synthetic resin molded sheets of the present invention in Examples 2-8 have high total light transmittance and maintain the overall brightness. Compared with Examples 11-13 (comparative examples), the diffusion coefficient is also high and the light source image is also good. The synthetic resin molded sheet of the present invention in Example 9 not only eliminates the shadow of the fluorescent lamp, but also has a high total light transmittance and is bright. The synthetic resin molded sheet of the present invention has good releasability of the molded product. In Example 14 (comparative example) and Example 15 (comparative example), the mold release from the mold was not smooth, and the desired surface irregularities could not be obtained by synthetic resin molding. board, so subsequent evaluations could not be performed.

As a study of the material used for the light-transmitting and diffusing synthetic resin of the present invention, evaluation was performed on a methacrylic resin mixed with a reactive polysiloxane and polymerized.

Example 16 (reference example)

Add and mix 90 parts by mass of methyl methacrylate (MMA), 5 parts by mass of neopentyl glycol dimethacrylate (NPG), and X, manufactured by Shin-Etsu Chemical Co., Ltd. represented by Chemical Formula 5 as a reactive polysiloxane compound. -5 parts by mass of 24-4044 (viscosity 821 mm ² /s, acryloyl equivalent 3600 g/mol), 0.015 parts by mass of naphthalimide fluorescent dye Lumogen Fviolet570 (LFV570) manufactured by BASF, 2,2'-azo Bis(2,4-dimethylvaleronitrile) (ADVN) 0.11 parts by mass, 2-(2'-hydroxyl-5-methylphenyl) benzotriazole 0.03 parts by mass, after defoaming, from the mold ( A U-shaped vinyl chloride cylinder is sandwiched between two matte glass plates of 1000×1500×10 mm used in Example 12, and a mold composed of glass tanks is assembled, and vertically ground-maintained mold) into the tip, and kept in a water bath at 60°C for 2 hours, followed by keeping in an air bath at 120°C for 2 hours. After cooling, the glass plate of the glass cell was peeled off to obtain a light-transmitting and diffusing synthetic resin plate having a thickness of 2 mm.

Table 2 shows the optical properties. This light-transmitting and diffusing synthetic resin board eliminates the light source image of fluorescent lamps and emits bright white light as a whole, so it is also extremely useful as a material for backlit illuminated signboards, as well as a display for ingenuity and shielding. The state in which the submicron-order primary particles are aggregated to form secondary particles of several microns in size was observed using an electron microscope.

Example 17-21

Cast polymerization was carried out in the same manner as in Example 16, except that the amounts of the reactive polysiloxane compound, the crosslinkable vinyl monomer, and Lumogen Fviolet 570 (LFV570) were changed. The results are shown in Table 2.

Table 2 example 16 17 18 19 20 twenty one MMA (parts) 90.0 92.0 85.0 93.0 90.0 90.0 NPG(parts) 5.0 3.0 10.0 5.0 5.0 5.0 Reactive polysiloxane compound (parts) 5.0 5.0 5.0 2.0 5.0 5.0 LFV570(part) 0.015 - - 0 - - ADVN(parts) 0.11 0.11 0.11 0.11 0.055 0.22 Primary particle size (μm) 0.2～0.4 0.1～0.5 0.05～0.1 0.1～0.2 0.05～0.1 0.1～0.3 Secondary particle size (μm) 2～5 1～3 1～10 2～3 5～10 2～4 Total light transmittance τt(%) 45.7 45.3 46.2 58.1 44.1 43.4 Diffusion coefficient D 0.959 0.955 0.967 0.735 0.978 0.947 Light fastness test ΔE 0.74 0.68 0.70 0.75 0.76 0.70 Heat distortion temperature (°C) 116 109 126 116 116 116

Example 22-23 (reference example)

Cast polymerization was carried out in the same manner as in Example 16, except that the diffusing agents shown in Table 3 were blended instead of the reactive polysiloxane compound. The results are shown in Table 3.

table 3 example twenty two twenty three MMA (parts) 96.0 96.0 NPG(parts) - - Diffusion agent type calcium carbonate Barium sulfate Amount of diffusing agent (parts) 4.0 4.0 Particle size (μm) 5 3 Total light transmittance τt(%) 52.1 44.8 Diffusion coefficient D 0.923 0.956 Light fastness test ΔE 1.7 1.8 Heat distortion temperature (°C) 103 103

Synthetic resin obtained by mixing and polymerizing reactive polysiloxane compounds has high light transmission and high light diffusivity, and heat resistance, and is suitable for materials such as light diffusion plates. Using such a material, the evaluation of the synthetic resin which provided the surface uneven|corrugated shape was performed.

Example 24 (embodiment)

Using the glass used in Example 1, it was opposed so that the surface formed with the desired surface shape was on the inside, a soft vinyl chloride resin gasket was sandwiched so that the gap was 2 mm, and a glass cell was assembled.

Add and mix 90 parts by weight of methyl methacrylate (MMA), 5 parts by weight of neopentyl glycol dimethacrylate (NPG), and X, manufactured by Shin-Etsu Chemical Co., Ltd. as shown in Chemical Formula 5 as a reactive polysiloxane compound. -5 parts by weight of 24-4044 (viscosity 821 mm ² /s, acryloyl equivalent 3600 g/mol), 0.015 parts by weight of naphthalimide fluorescent dye Lumogen Fviolet570 (LFV570) manufactured by BASF, 2,2'-azo 0.11 parts by weight of bis(2,4-dimethylvaleronitrile) (ADVN), 0.03 parts by weight of 2-(2'-hydroxyl-5-methylphenyl)benzotriazole, after defoaming, inject the slurry into In a glass cell, it was kept in a water bath at 60° C. for 2 hours, and then kept in an air bath at 120° C. for 2 hours. After cooling, the glass plate of the glass cell was peeled off to obtain a light-transmitting and diffusing synthetic resin plate having a thickness of 2 mm. Table 4 shows the evaluation results of mold release properties, surface irregularities, electron microscope observation, optical properties, and material properties during plate production. The synthetic resin board not only almost completely eliminates the filament image of the incandescent light bulb, but also keeps the total light transmittance high. It is extremely useful as a backlight light diffuser for high-performance signage and various displays.

Example 25 (embodiment)

Except for changing the addition amount of methyl methacrylate (MMA), reactive polysiloxane compound (X-24-4044), and Lumogen Fviolet 570, a light-transmitting diffusible compound with a thickness of 2 mm was obtained in the same manner as in Example 24. Resin board. The evaluation results are shown in Table 4.

Example 26-31 (embodiment)

Using the mold glass with various surface irregularities used in Examples 3-8, and making the addition amount of Lumogen Fviolet 570 the same as that of Example 25, a light-transmitting and diffusing synthetic resin plate with a thickness of 2 mm was obtained. The evaluation results are shown in Table 4.

Table 4 example twenty four 25 26 27 28 29 30 31 composition MMA (parts) 90 90.6 90 90 90 90 90 90 Reactive polysiloxane compound (parts) 5 4.4 5 5 5 5 5 5 LFV570(part) 0.015 0 0 0 0 0 0 0 particle size Primary particle size (μm) 0.2～0.4 0.1～0.2 0.1～0.5 0.2～0.5 0.1～0.4 0.2～0.5 0.05～0.2 0.1～0.5 Secondary particle size (μm) 2～5 1～3 2～5 2～8 3～5 2～6 3～7 2～5 Surface bump shape P(μm) 10 10 15 20 15 20 40 45 Rz(μm) 5 5 10 10 5 5 12 12 Rz/P 0.5 0.5 0.67 0.5 0.33 0.25 0.3 0.26 θ (degrees) 50 50 55 50 40 30 30 28 productivity Mold release ○ ○ ○～△ ○ ○ ○ ○ ○ optical properties τt(%) 45 50 43 45 47 47 48 49 D. 0.99 0.985 0.995 0.99 0.985 0.975 0.97 0.96 Light Source Image (Test 2) ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ physical properties Load deflection temperature (°C) 116 114 116 117 115 116 117 115

The synthetic resin molded article of the present invention maintains high diffusion performance and light transmittance, and at the same time has good releasability of the molded article, and is a molded article excellent in industrial productivity.

Claims (10)

1. light transmission diffusibility synthetic resin formed product, it has formed concaveconvex shape at least one surface, and the tiltangle of concaveconvex shape is 20 degree-60 degree.

2. light transmission diffusibility synthetic resin formed product according to claim 1, wherein, the average peak of concaveconvex shape P at interval is 5 μ m-50 μ m, 10 mean roughness Rz in the surfaceness standard are 3 μ m-15 μ m.

3. light transmission diffusibility synthetic resin formed product according to claim 2, wherein, Rz/P is 0.2-0.7.

4. according to each described light transmission diffusibility synthetic resin formed product of claim 1-3, it is characterized in that it is by being polymerized for the monomer mixture of liquid reactive polysiloxane compound at normal temperatures based on the unsaturated monomer of methyl methacrylate and 20-0.5 quality % of containing 80-99.5 quality %.

5. light transmission diffusibility synthetic resin formed product according to claim 4, it is characterized in that, contain: based on the simple function unsaturated monomer unsaturated monomer 80-99.9 quality % of methyl methacrylate with the bridging property vinyl monomer 20-0.1 quality % of the vinyl more than 2 is arranged in molecule based on the unsaturated monomer of methyl methacrylate.

6. according to claim 4 or 5 described light transmission diffusibility synthetic resin formed products, wherein, with respect to monomer mixture 100 mass parts, also further contain the 0.01-0.05 mass parts from naphthalimide with the fluorochrome of selecting the perylene dyestuff.

7. according to each described light transmission diffusibility synthetic resin formed product of claim 4-6, wherein the curing of reactive polysiloxane compound particle disperse with 1 particle diameter 0.05-1 μ m, 2 particle diameter 1-20 μ m.

8. light diffusing sheet comprises each described light transmission diffusibility synthetic resin formed product of claim 1-7.

9. the purposes of the light diffusing sheet that light diffusing sheet according to claim 8 is used as LCD.

10. the manufacture method of the described light transmission diffusibility synthetic resin formed product of each of claim 1-7 is characterized in that, is that the pattern plate carries out cast polymerization with two glass plates.

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