JP4910311B2 - Thermoplastic transparent resin - Google Patents

Description

  The present invention relates to a thermoplastic transparent resin, a thermoplastic resin sheet using the thermoplastic transparent resin, a processed product of the thermoplastic resin sheet, and an optical article manufactured by injection molding of the thermoplastic transparent resin.

  Thermoplastic resin sheets are applied to transparent sheet substrates of various display devices, display front panels, and glazing in hospitals. Examples of the thermoplastic resin used include methacrylic resin (PMMA), polyethylene terephthalate resin (PET), polycarbonate resin (PC), and vinyl chloride resin (PVC). Although PMMA is excellent in surface hardness and weather resistance, it is poor in heat distortion resistance and low water absorption, and PET is excellent in impact resistance, but the surface hardness is not sufficient. PC is excellent in heat distortion resistance and impact resistance, but surface hardness, weather resistance, and chemical resistance are insufficient, and PVC has features such as low cost and flame retardancy. There is a problem of being scarce.

  Methyl methacrylate-styrene copolymer (hereinafter abbreviated as MS resin), which has been modified by copolymerization to give low water absorption, is widely used as a transparent sheet substrate for various display devices. Since it has a skeleton, its transparency is inferior to that of methacrylic resin, and its use may be limited. Further improvements are also required in terms of dimensional stability and heat distortion resistance.

  On the other hand, plastic optical articles such as plastic lenses and light guide plates manufactured by injection molding have been required to have high melt fluidity in addition to the physical properties described above. This is to increase the fluidity of the resin itself when it melts so that the resin reaches the mold details and precisely transfer the cavity shape.

  The fluidity of the molten resin can be controlled to some extent by the resin structure, molecular weight, and molding temperature. However, if the primary structure of the resin is changed to reduce the glass transition temperature, the heat distortion resistance of the molded article cannot be obtained. Lowering the molecular weight can also improve fluidity, but there are limitations in terms of mechanical properties. The higher the molding temperature, the higher the fluidity of the molten resin.However, the mechanical properties deteriorate due to thermal degradation, coloring, and the appearance of the molded product becomes poor due to gas generated from volatile components. Is limited.

  In particular, deterioration of color tone due to coloring is the most serious problem in optical article applications. In addition, a high degree of heat decomposability is also required from the viewpoint of recovering, crushing, remolding and reusing the molded end material. Until now, attempts have been made to improve thermal decomposition with additives, but in optical article applications, it is necessary to eliminate additives as much as possible to enhance optical purity. Therefore, it is required to improve the heat decomposability of the resin itself so that coloring due to decomposition or the like does not occur.

  The technology for hydrogenating aromatic rings of styrene resins (hydrogenation of aromatic double bonds) has been known for a long time. Polyvinylcyclohexane obtained from polystyrene has the disadvantage of being inferior in mechanical strength. It is a resin with excellent heat distortion resistance. Due to its excellent transparency and heat distortion resistance, application to optical disk substrates has been studied (see Patent Document 1). Examples have been disclosed in which a resin having a specific monomer composition obtained by hydrogenating an aromatic double bond of MS resin is applied to optical disk applications and plastic lens applications (see Patent Document 2 and Patent Document 3). However, since the resins disclosed therein contain 50% or more of the vinylcyclohexane repeating units, the adhesiveness with the metal is insufficient and the heat distortion resistance is not always sufficient. For this reason, the performance required for the optical disk substrate may not be fully exhibited. Moreover, in the case of a plastic lens or the like, practical performance may not be satisfied in terms of mechanical properties.

  A specific example of the optical article is a backlight type light guide plate of a surface light emitting device. A light guide plate of 20 inches or less is often manufactured by injection molding, and a light guide plate used for a large surface light emitting device exceeding 20 inches is often manufactured by cutting out from a thermoplastic resin sheet. In particular, in recent years, liquid crystal display devices have become larger in size, and surface light-emitting devices having high luminance and uniform light emission performance without uneven brightness have been demanded. In addition, with the increasing demand for color display, there is currently a demand for surface light emitting devices that are excellent in color tone reproducibility and color tone stability. Furthermore, in recent years, in order to improve the brightness, the surface light emitting device is operated under more severe conditions, so that the light guide plate is deteriorated and colored, and the color tone of the emitted light changes. Yes.

  As a solution to these problems, many attempts have been made to add various antioxidants and UV absorbers, and to correct the color tone using additives. However, this results in uneven brightness and uneven colors, resulting in fine color display. Making it difficult.

  Further, with the increase in size of the screen, further low water absorption has been required. This is because when the resin absorbs water, warping occurs, resulting in luminance unevenness and color unevenness.

  An optical screen such as a transmissive screen of a projection television is usually composed of a lens unit such as a Fresnel lens sheet or a lenticular lens sheet. The Fresnel lens sheet is obtained by forming a Fresnel lens on a thermoplastic resin substrate, and the lenticular lens sheet is obtained by forming a lenticular lens on a thermoplastic resin substrate. A Fresnel lens is a lens whose lens surface is stepped, not continuous, and can also be considered as a concentric prism. A lenticular lens is a plate-like lens array in which semi-cylindrical lenses are arranged side by side so that their longitudinal axes are parallel. As the resin for the substrate, an acrylic resin is employed from the viewpoint of transparency, and includes an acrylic resin to which a rubber component having a multilayer structure is added (see Patent Document 4) and a tertiary butyl cyclohexyl methacrylate unit. A methacrylic resin (see Patent Document 5), a methyl methacrylate-styrene copolymer resin (see Patent Document 6) in which styrene is copolymerized at a ratio of 36% by weight, and the like are disclosed.

  If a resin with high water absorption such as PMMA is used as the resin for the substrate, the dimensional change of the screen is likely to occur. Conversely, when a resin with low polarity such as polystyrene is selected, the water absorption is small but the surface adhesion is small. In some cases, the lens made of an ultraviolet curable resin formed on the substrate may peel off. In recent years, the light source has been changed from a CRT to a liquid crystal display device, and the substrate is strongly required to have no birefringence. That is, there is a demand for a resin for a substrate that has a good balance of low water absorption, low birefringence, and good adhesion to an ultraviolet curable resin.

  Furthermore, there is a front panel of a display device as an example of an optical article. Antireflection performance, scratch resistance, antifouling performance, etc. are important. In addition, it is essential that the transmitted light be as homogeneous as possible in the visible light region as well as not causing warpage due to water absorption.

  On the other hand, optical articles that require a plate shape or a complicated structure, such as a light guide plate with a small size, are mainly manufactured by injection molding.

  An example of another optical article manufactured by injection molding is a plastic lens. It is important that the material has good transferability (reproducibility of the cavity shape) of the thin portion. In recent years, in order to improve the recording density of optical information recording media, it has been studied to shorten the laser wavelength for recording and reproducing information, particularly 350 to 450 nm, and a lens that can cope with this is required. ing.

  Vinyl alicyclic hydrocarbon-based resins (see Patent Document 7) have been disclosed as resins suitable for plastic lenses, particularly resins capable of dealing with a blue laser of around 405 nm, but they have moldability, transparency and light resistance. Inadequate in terms. In addition, even when the lens is molded without any problem, there is a problem of low practical mechanical properties such as the lens holding portion being cracked during mounting.

Polycarbonate is mainly used for optical recording medium substrates, which are other specific examples of optical articles, but recordings represented by the development of large-capacity magneto-optical recording disks, the development of digital versatile disks, and the development of blue lasers. As the density increases, birefringence and warping are becoming problems. Hydrogenated polystyrene has been proposed as an alternative material for polycarbonate (see Patent Document 8). Further, a hydride of a styrene-conjugated diene block copolymer in which a rubber component is introduced by block copolymerization of a conjugated diene such as isoprene or butadiene with styrene has been reported (see Patent Document 9). However, these hydrogenated styrene-based aromatic hydrocarbon polymers may have high haze when the hydrogenation is incomplete, and there is a problem in using them as an optical recording medium substrate.
Japanese Patent Laid-Open No. 63-43910 JP-A-6-25326 JP-A-4-75001 Japanese Patent Laid-Open No. 1-128059 JP-A-2-254434 JP-A-9-302176 JP 2001-272501 A Japanese Examined Patent Publication No. 7-114030 Japanese Patent No. 2730053

  The present invention provides a thermoplastic transparent resin having an excellent balance of transparency, heat distortion resistance, heat decomposition resistance, mechanical properties, low water absorption, weather resistance, and light resistance required for the thermoplastic transparent resin described above. The purpose is to do. Another object of the present invention is a plastic optical article excellent in balance of transparency, heat distortion resistance, heat decomposition resistance, mechanical properties, low water absorption, weather resistance, light resistance, etc., using the thermoplastic transparent resin. Is to provide.

  The resin in which the aromatic double bond of the MS resin (MMA constituent unit / styrene constituent unit = 0.92 or less) disclosed in Patent Document 2 and Patent Document 3 having a low MMA copolymerization rate is hydrogenated is a machine In some cases, the strength is not always sufficient and it cannot be practically used. As a result of intensive studies in view of the above circumstances, the present inventors have obtained a copolymer comprising a specific constituent unit composition obtained by polymerizing a monomer composition containing a (meth) acrylic acid ester monomer and an aromatic vinyl monomer. Thermoplastic resin obtained by hydrogenating 70% or more of aromatic double bonds has very good transparency, heat distortion resistance, heat decomposition resistance, mechanical properties, low water absorption, weather resistance, and light resistance. It has been found that there is a balance, and the present invention has been reached.

  That is, the present invention is obtained by polymerizing a monomer composition containing at least one (meth) acrylic acid ester monomer and at least one aromatic vinyl monomer, and is a structural unit derived from an aromatic vinyl monomer (B Obtained by hydrogenating 70% or more of the aromatic double bond of the copolymer whose molar ratio (A / B) of the structural unit (A mole) derived from the (meth) acrylic acid ester monomer to (mol) is 1-4. The present invention relates to a thermoplastic transparent resin.

  Furthermore, the present invention provides a thermoplastic resin sheet made of the thermoplastic transparent resin, a multilayer thermoplastic resin sheet having a layer made of the thermoplastic transparent resin, and a backlight type light guide plate produced using the thermoplastic transparent resin. The present invention relates to an optical article such as a lens unit, a display front panel, a light guide plate, a plastic lens, and an optical recording medium substrate.

  The thermoplastic transparent resin obtained by the present invention is particularly excellent in thermal decomposition resistance. When the optical material composition containing the thermoplastic transparent resin is molded, it is possible to produce a molded article such as an optical article that has few molding defects due to thermal deterioration or the like and has excellent color tone. Furthermore, since the balance of transparency, heat distortion resistance, mechanical properties, low water absorption, low birefringence, weather resistance, light resistance, etc. is excellent, a high-quality optical article can be produced.

  Specific examples of (meth) acrylate monomers used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, and (meth) acrylic. (Meth) acrylic acid alkyls such as stearyl acid, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate; (meth) acrylic acid (2-hydroxyethyl) and (meth) acrylic acid (2-hydroxypropyl), Hydroxyalkyl (meth) acrylates such as (meth) acrylic acid (2-hydroxy-2-methylpropyl); (meth) acrylic acid (2-methoxyethyl), (meth) acrylic acid (2-ethoxyethyl), etc. (Meth) acrylic acid alkoxyalkyls; benzyl (meth) acrylate and (meth) acrylic (Meth) acrylic acid esters having an aromatic ring such as phenyl acid; and (meth) acrylic acid esters having a phospholipid-like functional group such as 2- (meth) acryloyloxyethyl phosphorylcholine, etc. From the balance of physical properties, it is preferable to use alkyl methacrylate alone or to use alkyl methacrylate and alkyl acrylate together. Furthermore, it is preferable to use methyl methacrylate 80-100 mol% and alkyl acrylate 0-20 mol%. Of the alkyl acrylates, methyl acrylate or ethyl acrylate is particularly preferred. In the present invention, (meth) acrylic acid refers to methacrylic acid and / or acrylic acid.

  Specific examples of the aromatic vinyl monomer used in the present invention include aromatic vinyl compounds such as styrene, α-methylstyrene, p-hydroxystyrene, alkoxystyrene, and chlorostyrene, and styrene is preferably used.

  A known method can be used for the polymerization of the (meth) acrylic acid ester monomer and the aromatic vinyl monomer, but industrially, a method based on radical polymerization may be simple. For the radical polymerization, a known method such as a bulk polymerization method, a solution polymerization method, an emulsion polymerization method or a suspension polymerization method can be appropriately selected. For example, the bulk polymerization method and the solution polymerization are performed by a continuous polymerization method in which a monomer composition containing a monomer, a chain transfer agent, and a polymerization initiator is continuously fed to a complete mixing tank and polymerized at 100 to 180 ° C. . In the solution polymerization method, hydrocarbon solvents such as toluene, xylene, cyclohexane and methylcyclohexane; ester solvents such as ethyl acetate; ketone solvents such as acetone and methyl ethyl ketone; ether solvents such as tetrahydrofuran and dioxane; methanol, isopropanol and the like A solvent such as an alcohol solvent is fed to the polymerization tank together with the monomer composition. After the polymerization, the reaction solution can be extracted from the polymerization tank, and the volatile matter can be removed with an extruder or a vacuum tank to obtain a copolymer.

  In the case of a methacrylic copolymer, the constituent unit ratio of the copolymer does not necessarily coincide with the charged monomer ratio, and is determined by the amount of monomer actually incorporated into the copolymer by the polymerization reaction. The constitutional unit ratio of the copolymer is the same as the charged monomer ratio when the polymerization conversion rate of the monomer is 100%, but in fact, it is often produced at a polymerization conversion rate of 50 to 80% and is highly reactive. Since the monomer is more easily incorporated into the polymer, there is a difference between the monomer charging ratio and the constituent unit ratio of the copolymer. For this reason, a desired monomer unit ratio is obtained by appropriately adjusting the charged monomer ratio.

  The constituent unit molar ratio ((meth) acrylic acid ester monomer unit / aromatic vinyl monomer unit = A / B) of the copolymer used for the hydrogenation reaction in the present invention is 1 to 4. If it is less than 1, the mechanical strength is inferior and may not be practically used. When it exceeds 4, since there are few aromatic double bonds hydrogenated, effects, such as a glass transition temperature improvement by a hydrogenation reaction, may be insufficient. The structural unit molar ratio (A / B) is preferably from 1 to 2.5, more preferably from 1 to 2, from the viewpoint of balance of physical properties.

  The copolymer is dissolved in a suitable solvent to perform a hydrogenation reaction. The hydrogenation reaction solvent and the polymerization solvent may be the same or different. As the hydrogenation reaction solvent, a solvent that has a high solubility in the copolymer and hydrogen before and after the hydrogenation reaction and is inert to the hydrogenation reaction is preferable. For example, hydrocarbon solvents such as cyclohexane and methylcyclohexane; ester solvents such as ethyl acetate; ketone solvents such as acetone and methyl ethyl ketone; ether solvents such as tetrahydrofuran and dioxane; alcohol solvents such as methanol and isopropanol are used. .

  The hydrogenation reaction is preferably performed at a hydrogen pressure of 3 to 30 MPa and a reaction temperature of 60 to 250 ° C. using a known method such as a batch reaction or a continuous flow reaction. If the reaction temperature is too low, the reaction does not proceed easily. If the reaction temperature is too high, the molecular weight may be reduced due to the cleavage of the molecular chain, or the ester moiety may be hydrogenated. In order to prevent molecular weight reduction due to molecular chain scission and allow the reaction to proceed smoothly, the temperature, hydrogen pressure, etc., depend on the type of catalyst used, the concentration in the reaction system, the concentration of the copolymer in the reaction system, the molecular weight, etc. Is preferably selected as appropriate.

  A known hydrogenation catalyst can be used. Specifically, metals such as nickel, palladium, platinum, cobalt, ruthenium and rhodium, or compounds such as oxides, salts and complexes of such metals are used as porous carriers such as carbon, alumina, silica, silica / alumina, and diatomaceous earth. Examples include a supported solid catalyst. Among these, a catalyst in which nickel, palladium, or platinum is supported on carbon, alumina, silica, silica / alumina, or diatomaceous earth is preferably used. The supported amount is preferably 0.1 to 30 wt% of the carrier.

  The hydrogenation rate is 70% or more of the total aromatic double bond, preferably 80% or more, more preferably 90% or more (including 100%). If it is less than 70%, the resin may become cloudy and the transparency may be lowered, and the performance improvement effect due to the improvement of the glass transition temperature is also small.

Since the thermoplastic transparent resin of the present invention transmits light in the visible light region satisfactorily, the appearance is transparent. Since the loss due to reflection on the surface of the molded product is unavoidable, the upper limit of the total light transmittance depends on the refractive index (n _D ). The reflectivity R of the surface is R = (n _D −1) ² / (n _D +1) ² in the case of normal incidence, and the total light transmittance of the material represented by the refractive index n _D is two times on the front and back sides. Since there is reflection, 100 × (1-2R)% is the upper limit. The total light transmittance of the molded product having a thickness of 3.2 mm according to the present invention is preferably 90% or more. When used as an optical material, higher transparency may be required, and the total light transmittance is more preferably 91% or more, and most preferably 92% or more.

  The thermoplastic transparent resin of the present invention is particularly excellent in thermal decomposition resistance under a nitrogen atmosphere. In the vicinity of 260 ° C. where the methacrylic resin is actually molded by injection molding or extrusion molding, zipper decomposition specific to the methacrylic resin occurs. This is known to proceed starting from the terminal double bond. By suppressing the thermal decomposition in the vicinity of 260 ° C., molding defects such as silver streak generation and foaming can be reduced, and stable optical articles can be produced without deteriorating the color tone. In the present invention, the thermal decomposition resistance was evaluated using a thermogravimetric analyzer. 5 mg of resin was placed on a platinum pan and 300 ml / min. The weight loss change when held at 260 ° C. (± 2.0 ° C.) for 3 hours in a nitrogen stream was measured, and the thermal weight loss rate was evaluated as thermal decomposition resistance. The thermal weight loss rate is preferably 5 wt% or less, more preferably 3 wt% or less, and most preferably 2 wt% or less (including zero). As described above, the hydrogenation rate of the thermoplastic transparent resin of the present invention is 70% or more of the total aromatic double bond, but the hydrogenation rate is deeply involved in the expression of heat decomposability. Since the hydrogenation of the terminal double bond proceeds in preference to the hydrogenation of the aromatic double bond, the thermal decomposition resistance is improved when the hydrogenation rate of the aromatic double bond is 70% or more.

  The bending strength of the thermoplastic transparent resin of the present invention is preferably 70 to 130 MPa, more preferably 74 to 130 MPa, and has sufficient mechanical properties for use as an optical material.

  The thermoplastic transparent resin of the present invention can be heated and melted to have a desired shape. Molding can be performed by a known injection molding method or extrusion molding method. Since the thermoplastic transparent resin of the present invention is particularly excellent in heat decomposability, it is possible to produce a molded product excellent in color tone with few molding defects due to thermal degradation or the like by any method. Specific uses of molded products include various light guide plates, various light guides, optical fibers, display front panels, plastic lenses, prisms, lens unit substrates, optical filters, optical films, optical recording media bases, and the like that transmit light. Optical articles to be used can be given.

  In addition, since the thermoplastic transparent resin of the present invention has a low birefringence, the optical article is optimal for applications that need to transmit polarized light regardless of molding means and shape. Specifically, it can be particularly suitably used for a light guide plate of a liquid crystal display, a plastic lens, a substrate of a lens unit, an optical recording medium substrate, and the like.

The thermoplastic transparent resin of the present invention preferably contains as few foreign particles as possible. The foreign substances are substances that are not compatible with the resin, such as impurities mixed from the outside, catalyst residues, gelled products, side reaction products, and the like mixed in the polymer production process. Except for the case where a light diffusing agent is added and the transmitted light is intentionally scattered to be used, in applications that do not use scattered light, a large number of foreign particles is not preferable because the loss of transmitted light increases. The thermoplastic transparent resin preferably contains substantially no foreign particles having a particle size of 1 μm or more, and the content of foreign particles having a particle size of 0.5 μm or more and less than 1 μm is 3 × 10 ⁴ particles / g or less. It is preferable that it is 2 × 10 ⁴ pieces / g or less. The particle size is measured using a light scattering fine particle detector. In particular, when high transparency is required, the content of foreign particles having a particle size of 0.5 μm or more and less than 1 μm is preferably 5 × 10 ³ particles / g or less. The method for reducing the content of the foreign particles is not particularly limited, but in the production process of the thermoplastic transparent resin, the solution containing the polymer is a membrane filter having a pore size of 0.5 μm or less, preferably 0.2 μm or less, Examples thereof include a method of filtering at least once or a method of filtering with a filter having a charge-capturing function. Contain foreign particles by performing exposure to the atmosphere in a clean environment as much as possible, such as cooling the strand melted and discharged from the extruder, pelletizing process, sheeting process, and introducing pellets into the injection molding machine. The amount can be reduced. It is preferable to perform at least one of these steps in an environment having a cleanliness of class 5 or higher as defined by ISO 14644-1.

  The content of volatile components other than various additives in the thermoplastic transparent resin of the present invention is preferably 3000 ppm or less, more preferably 1000 ppm or less, and even more preferably 500 ppm or less (including zero). In particular, in order to obtain a high-quality optical article, the content of volatile components is preferably reduced to 500 ppm or less, more preferably 300 ppm or less, and particularly preferably 200 ppm or less. Examples of the volatile component include an organic solvent, an unreacted monomer, or a modified product thereof. When there are many volatile components, flow marks, voids, surface defects and the like are likely to occur during molding, and the homogeneity of the obtained optical article is impaired. The method for reducing the volatile component is not particularly limited, and examples include performing the polymer extrusion step under conditions suitable for solvent removal.

(A) Thermoplastic resin sheet The most important usage pattern of the thermoplastic transparent resin of the present invention is a thermoplastic resin sheet obtained by extrusion molding. In general, thermoplastic resin sheets are manufactured by the casting method, in which the resin is dissolved in a solvent and cast, and the solvent is volatilized, or the resin pellets are placed in a plate-shaped mold and heated to apply pressure. However, it is preferable to produce the resin by melt extrusion molding with a sheet extruder equipped with a T-die (also referred to as a flat die) in a single-screw extruder or a twin-screw extruder.

  The thermoplastic resin sheet preferably has a thickness in the range of 0.01 to 10 mm. Within the above range, the mechanical strength is sufficient, and the secondary workability by thermoforming is also good. Although thickness changes with uses, More preferably, it is 0.1-8 mm, More preferably, it is 0.5-5 mm.

  The resin temperature during extrusion is 200 to 300 ° C. If it is less than 200 ° C., the fluidity of the resin is insufficient, the shape of the roll surface is not transferred, and the transferability of the sheet surface is poor. On the other hand, when the temperature exceeds 300 ° C., the resin is decomposed, which causes coloring, deterioration of heat distortion resistance, deterioration of working environment due to odor, and the like, which is not preferable. The resin temperature during extrusion is more preferably 220 to 280 ° C.

  The thermoplastic resin sheet of the present invention is transparent in appearance because it transmits light in the visible light region well unless an additive such as a light diffusing agent or pigment is added or the surface is roughened. The total light transmittance of a blank sheet (thickness 3.2 mm) made of only a thermoplastic resin is 90% or more. Since the loss of light due to reflection on the surface of the molded product is unavoidable, the upper limit of this total light transmittance depends on the refractive index, but when used as an optical material, higher transparency may be required. More preferably, it is 91% or more, and most preferably 92% or more.

Since the thermoplastic resin sheet of the present invention has excellent transparency in a wide wavelength range, it has good weather resistance and light resistance. This is in response to market demands for reducing the change in color tone when used indoors and outdoors for a long period of time. The change in color tone can be evaluated using the change in YI value (ΔYI). A small change in YI value indicates excellent weather resistance and light resistance. Since YI is a method for evaluating yellowness, it is possible to reduce ΔYI to some extent by adding a colorant, but since the color tone is blackish, the light transmittance decreases. There is. Moreover, although weather resistance and light resistance improve also by addition of a ultraviolet absorber and antioxidant, in this invention, it evaluated using the thermoplastic resin sheet which does not mix | blend color mixing or an additive. Although weather resistance and light resistance are not the same, they are common in terms of their ability to withstand resin degradation caused by light. Accordingly, in the present invention, the light resistance is measured by irradiation with a mercury lamp, and thereby the weather resistance is estimated. When the mercury lamp is irradiated for 600 hours under conditions of a distance to the sample of 30 cm, 0.8 mW / cm ² and a sample surface temperature of 60 ° C., the ΔYI of the 2.0 mm optical path length of the thermoplastic resin sheet of the present invention is preferably Is less than 2.

  The thermoplastic resin sheet of the present invention has high surface hardness and excellent scratch resistance. A thermoplastic resin sheet having low scratch resistance is easily scratched at the time of production or construction, and is therefore often subjected to a hard coat treatment. Of course, it is also possible to apply a hard coat to the thermoplastic resin sheet of the present invention. Since the performance of the hard coat also depends on the hardness of the sheet surface, the thermoplastic resin sheet of the present invention exhibits particularly high scratch resistance by applying the hard coat. In the present invention, the surface hardness was evaluated by pencil hardness. The surface hardness of the thermoplastic resin sheet of the present invention that has not been subjected to a hard coat treatment is preferably 2H or more, more preferably 3H or more. When the hard coat treatment is performed, the surface hardness is preferably 4H or more, more preferably 5H or more.

  The thermoplastic resin sheet of the present invention is also excellent in heat distortion resistance. The practical heat-resistant temperature varies depending on the shape of the molded body and distortion during molding, but is mainly determined by the glass transition temperature of the raw material. The glass transition temperature of the thermoplastic resin of the present invention is preferably 110 to 140 ° C.

  The thermoplastic resin sheet of the present invention has a small saturated water absorption rate and is excellent in dimensional stability. In general, a sheet-like molded body is required to have a low saturated water absorption rate because warpage and deflection occur when a distribution of water absorption occurs in the thickness direction. The saturated water absorption rate of the thermoplastic resin sheet of the present invention is preferably 0.1 to 1.2 wt%, more preferably 0.2 to 0.8 wt%.

  The thermoplastic resin sheet of the present invention has high heat decomposability without blending an antioxidant or the like, but the oxidation decomposability can be improved by blending an appropriate antioxidant. . Known antioxidants can be used, and specific examples include hindered phenolic antioxidants and phosphoric acid antioxidants, which may be used alone or in combination. The addition amount is preferably about 50 to 10,000 ppm with respect to the resin.

  In addition, other additives such as antistatic agents, colorants such as pigments and dyes, light diffusing agents, ultraviolet absorbers, release agents, as long as the physical property balance of the thermoplastic transparent resin of the present invention is not impaired as necessary. You may mix | blend a plasticizer, a lubricant, a flame retardant, a fungicide, etc.

  Since the thermoplastic transparent resin of the present invention is excellent in thermal decomposition resistance, it can be used by crushing the offcut discharged at the time of manufacturing the thermoplastic resin sheet and mixing it with the raw material resin, thus greatly improving the product yield. be able to. Usually, when a thermoplastic resin is repeatedly thermoformed, the thermoplastic resin deteriorates and becomes colored due to thermal history. However, the thermoplastic transparent resin of the present invention can minimize deterioration coloring. Of course, it is possible to re-mold the thermoplastic resin sheet only from the end material discharged during the production of the thermoplastic resin sheet, but in order to stabilize the quality of the thermoplastic resin sheet, it is preferable to mix it with the raw material resin. The mixing ratio of the mill ends is preferably 20% by weight or less, more preferably 10% by weight or less, and particularly preferably 5% by weight or less based on the total of the resin and the mill ends.

  The thermoplastic resin sheet of the present invention may be a single layer, but may have a multilayer structure by coextrusion molding. The layer structure, that is, the number of layers and the type of resin to be used can be arbitrarily determined. For example, in a two-layer / three-layer multilayer sheet, the resin of the present invention is used as a surface layer (skin layer). Surface characteristics such as scratch resistance are improved. At this time, a sheet excellent in weather resistance, light resistance, and low birefringence can be obtained. In particular, the core layer is formed of a resin having a benzene ring by coextrusion molding, and the skin layer is formed of the resin of the present invention. Then, in addition to excellent mechanical properties and low water absorption property balance, a multilayer sheet excellent in weather resistance, light resistance, and low birefringence can be obtained. As described above, when the surface layer is formed of the resin of the present invention, the weather resistance, light resistance, and low birefringence of the multilayer sheet can be remarkably improved even when the thickness is small. This is because weather resistance, light resistance, and low birefringence strongly depend on the properties of the surface layer resin. Specific examples of the resin having a benzene ring include styrene resin, MS resin, polycarbonate resin, polyester resin, and polyarylate resin. Among these, it is optimal to use MS resin from the viewpoint of balance of physical properties.

  Co-extrusion molding is performed by a known method, and using a co-extrusion molding machine equipped with a plurality of extruders and a die having a molten resin joining portion, various resins and the resin of the present invention are co-extruded and then cooled. Can be obtained. Although the thickness of a skin layer is not specifically limited, 10-1000 micrometers is preferable, More preferably, it is 50-500 micrometers, More preferably, it is 70-300 micrometers. The thickness of the core layer is preferably 0.01 to 10 mm, more preferably 0.1 to 8 mm, and still more preferably 0.5 to 5 mm.

(B) Light guide plate The thermoplastic resin sheet of the present invention is used for production of various optical articles. For example, a backlight type light guide plate can be produced by cutting out a thermoplastic resin sheet or a multilayer thermoplastic resin sheet. The light guide plate of the present invention is used for the purpose of emitting a line light source or a point light source in a planar shape. In order to achieve uniform surface emission (diffusibility) and prevent the image of the light source from appearing on the light exit surface (concealment), it is known that fine particles are dispersed in a thermoplastic resin sheet to scatter incident light. Use technology. Various studies have been made on the type, size, and amount of fine particles (see JP-A-7-214684).

  The type of fine particles is not particularly limited, but for example, organic fine particles such as methyl methacrylate polymer crosslinked particles, styrene polymer crosslinked particles, methyl methacrylate-styrene copolymer crosslinked particles, crosslinked siloxane fine particles, calcium carbonate, barium sulfate. Inorganic fine particles such as titanium oxide can be used, and one or more of these can be arbitrarily selected and used. If the fine particle has a large difference in refractive index with the resin, the light diffusion performance is large and the addition amount may be small. A range of 15. The average particle diameter of the fine particles is preferably 0.1 to 20 μm. If it is less than 0.1 μm, not only light diffusion performance cannot be obtained, but also the color tone of the light-emitting surface of the light guide plate changes to yellow, which is not preferable. If it exceeds 20 μm, the light diffusibility is lowered and the surface smoothness may be inferior. The average particle diameter is more preferably 0.1 to 15 μm, and further preferably 2 to 10 μm.

  The backlight type light guide plate of the present invention is excellent in light resistance, and it is not particularly necessary to add an antioxidant or an ultraviolet absorber, but it is a known oxidation as long as it does not adversely affect color tone reproducibility and color tone stability. Inhibitors and UV absorbers can be used. Specific examples include hindered phenolic antioxidants and phosphoric acid antioxidants, which may be used alone or in combination. The addition amount is preferably about 50 to 500 ppm relative to the resin.

  In addition, glycerin fatty acid esters such as glycerin monostearate, higher alcohols such as stearyl alcohol, higher fatty acids such as stearic acid may be added as a release agent, colorant, antistatic agent, impact modifier, etc. May be added. The addition amount is in a range that does not impair the object of the present invention, and is usually preferably 5000 ppm or less.

(C) Lens unit using thermoplastic resin sheet as substrate The thermoplastic resin sheet or multilayer thermoplastic resin sheet can be used as a substrate of a lens unit. A lens unit is obtained by forming at least one type of lens on one or both sides of a substrate (sheet) cut out from the sheet. Specifically, the substrate is a substrate used for a lens unit of an optical screen, for example, a transmissive screen of a projection television.

  When the lens unit is a Fresnel lens sheet, a Fresnel lens may be formed on the surface of the sheet by hot press molding of the sheet (substrate), or an ultraviolet curable resin is cured on the surface of the sheet to form a Fresnel lens. It may be formed. In the case of a lenticular lens sheet, the lenticular lens can be formed on the sheet surface simultaneously with the sheet molding by extrusion molding through a mold roll provided with a cavity having the shape of a lenticular lens. From the viewpoint of productivity, it is preferable to attach a film on which a lens is formed in advance, or to form a lens using an ultraviolet curable resin.

  The lens unit substrate of the present invention is improved in light diffusion agent, ultraviolet absorber, antioxidant, colorant, plasticizer, mold release agent, colorant, antistatic agent, impact resistance when forming a sheet, if necessary. One or more additives such as an agent can be blended.

(D) Front panel A display front panel can be produced by cutting out from the thermoplastic resin sheet or the multilayer thermoplastic resin sheet. As described above, it is known that the hard coat reflects the surface hardness of the substrate surface to some extent. That is, even if a hard coat is applied to a material having a low surface hardness, a hard coat with sufficient hardness may not be obtained. Since the display front panel of the present invention has a high surface hardness and scratch resistance, the surface characteristics can be further improved by subjecting the surface to a hard coat treatment. If necessary, one or more additives such as a light diffusing agent, an ultraviolet absorber, an antioxidant, a colorant, a plasticizer, a mold release agent, a colorant, an antistatic agent, and an impact resistance improving agent may be used during sheet molding. Two or more kinds can be blended.

  The hard coat layer may be a known one used for this purpose. The hard coat layer is made of, for example, a polyfunctional polymerizable compound containing two or more (meth) acryloyl groups such as urethane (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate, such as ultraviolet rays and electron beams. It can be formed by a method of polymerizing and curing by an activation energy ray, a method of curing a silicon-based, melamine-based, or epoxy-based crosslinkable resin material by heat. The hard coat layer may contain inorganic oxide particles such as silicon dioxide, aluminum oxide, magnesium oxide, tin oxide, silicon monoxide, zirconium oxide, and titanium oxide. In order to form the hard coat layer, the hard coat raw material liquid is applied to the substrate by a known method such as a spin coat method or a roll coat method, and then the hard coat raw material is cured by ultraviolet rays, electron beams, or heat. At this time, the hard coat raw material liquid may be diluted with various solvents for easy adhesion of the coating film or for adjusting the film thickness of the coating film.

  An antireflection layer may be formed on the front panel. The forming method is not particularly limited, and it is formed by a known method. As the antireflection layer, for example, a single layer or multilayer thin film of an inorganic oxide or an inorganic halide formed by a known method such as a vacuum deposition method, an ion plating method, a sputtering method, or a fluorine-containing polymer is coated. The thin layer etc. which are formed are mentioned.

  In addition, for the purpose of imparting near-infrared light absorbing ability and electromagnetic wave shielding ability, a metal salt such as a copper salt can be contained, or a conductive layer can be provided.

  As described above, the thermoplastic resin sheet of the present invention may be used in the form of a sheet as it is, but may be further processed into a sheet molded body having a desired shape by a known thermoforming such as vacuum / pressure forming. Good. Specific examples of the sheet molded body include the optical articles described above, automobile and aircraft instrument panels, laminate sheet base materials, medical device housings, building materials, and the like.

(E) Injection-molded optical article Although extrusion molding for producing a sheet-like molded product has been described as the resin molding method of the present invention, another important molding method is injection molding. The cylinder temperature for injection molding is preferably 220 to 320 ° C, more preferably 230 to 300 ° C. If the cylinder temperature is too high, the resin may be decomposed or deteriorated, resulting in reduced strength characteristics or coloring. If it is too low, residual stress will be generated in the molded product, resulting in increased birefringence, cavity shape, etc. The transferability of the ink may deteriorate. The mold temperature is preferably 50 to 180 ° C, more preferably 80 to 150 ° C. If the mold temperature is too high, mold release failure occurs, and the molding cycle becomes longer, resulting in poor productivity. If it is too low, the birefringence becomes large or the transferability becomes poor. The injection pressure is preferably 30 to 200 MPa, more preferably 60 to 150 MPa. The pressure holding time is preferably 1 to 300 seconds, more preferably 5 to 150 seconds. If the pressure holding time is too long, decomposition or deterioration of the resin occurs, and if it is too short, molding shrinkage increases. The cooling time is preferably 5 to 300 seconds, more preferably 10 to 150 seconds. If the cooling time is too long, the productivity decreases, and if it is too short, the birefringence increases or the transferability deteriorates. When the molding conditions are in the above range, the mechanical strength, birefringence, releasability, transferability, productivity, etc. of the optical article are balanced.

(F) Injection-molded light guide plate As described above, display light guide plates having a size of 20 inches or less are often manufactured by injection molding. In the planar light emitting device of this size, the direct method is not adopted, and an edge that emits light from the incident direction to the vertical direction by laying a cold cathode tube or LED light source as a linear light source from the end surface of the wedge-shaped injection molded plate A planar light emitting device of a light (also referred to as a side light) type is common.

  This light guide plate is subjected to various processing in order to uniformly emit incident light in a plane shape on the exit surface, for example, a light diffusion process for making the exit light uniform on the light exit surface, In order to make the emitted light uniform on the surface opposite to the light emitting surface, dot printing using white ink is performed or prism-shaped fine processing is performed. Moreover, you may perform processes, such as sticking light reflection layers, such as a silver vapor deposition sheet | seat and a white film, around circumference | surroundings other than the light-projection surface of a light guide. Although it may be processed after injection molding, it is more efficient and preferable to form a surface shape at the same time by applying a pattern to the mold during molding.

    Since the light guide plate obtained by injection molding the resin of the present invention has a high visible light transmittance, by incorporating the light guide, it is possible to provide a high-performance planar light emitting device with high emission light brightness. It is possible. The planar light emitting device includes a light guide plate and a light source. For example, it is used for mobile phones, mobile terminals, cameras, watches, notebook computers, displays, lighting, signals, automobile tail lamps, heat display of electromagnetic cookers, etc., with a light source placed on the thick end of a wedge-shaped light guide plate. Edge type surface light source. As a light source, a self-luminous body such as a cold cathode tube, an LED, and an organic EL can be used in addition to a fluorescent lamp.

(G) Injection-molded plastic lens A plastic lens can be produced by injection-molding the resin of the present invention. The plastic lens of the present invention is most suitable for an optical information recording medium such as an optical disk and a magneto-optical disk, and an optical lens for a pickup device of an optical recording / reproducing apparatus for recording and reproducing information.

  In general, a residual stress is generated in an optical article manufactured by injection molding, and birefringence is generated. When a plastic lens having a large birefringence is used in an optical pickup device, the spot shape is deformed into an elliptical shape, and recording and reproduction of the optical information recording medium cannot be performed satisfactorily. When the resin of the present invention is used, a molded product having a small birefringence can be obtained.

(H) Injection-molded optical recording medium substrate The resin of the present invention is also suitably used for production of an optical recording medium substrate by injection molding. By using the resin of the present invention, it is possible to produce an excellent substrate for an optical recording medium having performances such as high light transmittance, low haze, low water absorption, and low birefringence.

  Using a differential scanning calorimetry (DSC) apparatus of the resin of the present invention for producing an optical recording medium substrate, 10 ° C./min. The glass transition temperature measured at is preferably from 105 to 140 ° C, more preferably from 110 to 140 ° C. Within the above range, the fine structure applied to the optical recording medium substrate, that is, the land-groove structure and the pits can be stably maintained even when used in a high temperature environment, for example, at a high temperature of 80 ° C.

  The light transmittance of the optical recording medium substrate in the present invention is preferably 90% or more. Here, the light transmittance is obtained by measuring the total light transmittance of a molded plate having a thickness of 2 mm in accordance with JIS K7105-1981 (Measurement Method A). When the light transmittance is less than 90%, the light is absorbed in the resin, and thus it is not suitable as an optical recording medium substrate for the purpose of transmitting light.

  Further, the haze of the optical recording medium substrate in the present invention is desirably 1% or less. Here, haze is a value obtained by measuring the haze of a molded plate having a thickness of 2 mm in accordance with JISK7105. If the haze is greater than 1%, light is scattered, making it difficult to read information, which is not suitable as an optical recording medium substrate.

  The optical recording medium substrate of the present invention is used after being provided with a recording layer, a reflective layer, a protective layer and the like according to the purpose, and then pasted according to circumstances.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by these examples. The evaluation methods for the thermoplastic transparent resin, the thermoplastic resin sheet, the multilayer thermoplastic resin sheet, the backlight type light guide plate, the lens unit, the injection molded light guide plate, and the optical recording medium substrate are as follows.

I Evaluation method of thermoplastic transparent resin (1) Molar ratio of structural units in copolymer
^It calculated from the measured value of ¹ H-NMR (400 MHz: CDCl ₃ ).
(2) Hydrogenation rate It calculated | required by the decreasing rate of the absorption of 260 nm in the UV spectrum measurement before and behind hydrogenation reaction. From the absorbance A _{1 at} the concentration C ₁ of the resin before the hydrogenation reaction and the absorbance A _{2 at} the concentration C ₂ of the resin after the hydrogenation reaction, it was calculated from the following equation.
Hydrogenation rate = 100 × [1- (A ₂ × C ₁ ) / (A ₁ × C ₂ )]
(3) Thermal decomposability 5 mg of resin was placed on a platinum pan and 300 ml / min. Was measured for weight loss when kept at 260 ° C. (± 2.0 ° C.) for 3 hours, and the thermal weight reduction rate was defined as thermal decomposition resistance. A smaller number indicates that thermal decomposition does not occur, and is superior in heat decomposition resistance. The thermogravimetric analysis was performed using an RTG220 thermogravimetric measurement (TGA) apparatus manufactured by Seiko Electronics Industry.
(4) Glass transition temperature (Tg)
Using a DSC220 type differential scanning calorimetry (DSC) apparatus manufactured by Seiko Denshi Kogyo Co., Ltd., the resin amount was 10 mg, 10 ° C./min. The measurement was performed under the conditions described above, and the midpoint method was used.
(5) Total light transmittance A 3.2 mm-thick flat plate was measured by a transmission method using Z-Sensor Σ80NDH manufactured by Nippon Denshoku Industries Co., Ltd.
(6) Bending test Each 126 × 12 × 3.4 (mm) rectangular parallelepiped test piece obtained by injection molding was annealed for 16 hours at a temperature 20 ° C. lower than Tg, and 88 hours under conditions of 23 ° C. and 50 RH. This was done after conditioning. The bending strength and flexural modulus were measured according to JIS K7203.

II Evaluation Method for Thermoplastic Resin Sheet (7) Total Light Transmittance and Haze 2.0 mm thick thermoplastic obtained by melt extrusion using Nippon Denshoku Industries Co., Ltd. COH-300A The total light transmittance and haze of the resin sheet were measured by a transmission method.
(8) Light resistance A test piece cut into a 150 mm × 70 mm shape from a 2.0 mm thick thermoplastic resin sheet obtained by melt extrusion molding was placed in a sample holder of a fade meter. The light source of the fade meter was a mercury lamp H400-F for discoloration test manufactured by Harrison Toshiba Lighting Co., and the distance from the light source to the sample was 30 cm, before and after irradiation of the sample irradiated for 600 hours at an irradiation intensity of 0.8 mW / cm ² . The difference (ΔYI) in YI value was determined. The YI value was measured using a color / turbidity measuring machine COH-300A manufactured by Nippon Denshoku Industries Co., Ltd. The temperature of the sample surface during irradiation was 60 ° C.
(9) Surface Hardness Using a 2.0 mm thick thermoplastic resin sheet obtained by melt extrusion molding as a test piece, a pencil hardness test based on JIS K-5400 was performed and evaluated.
(10) Saturated water absorption A 50 mm square test piece was cut out from a 2.0 mm thick thermoplastic resin sheet obtained by melt extrusion molding. The test piece was dried with a hot air dryer at 80 ° C. until there was no change in weight, and the dry weight was determined. After being immersed in distilled water at room temperature and the water absorption amount was saturated, the weight of the test piece was determined (water absorption weight). The saturated water absorption was calculated by the following formula.
Saturated water absorption (%) = [(water absorption weight) − (dry weight)] / (dry weight) × 100
(11) Recyclability The end material discharged during the production of the thermoplastic resin sheet was crushed, and a predetermined amount was mixed with the raw material resin to form a 2.0 mm extruded resin sheet (recycled molded product). The YI values of the recycled molded body and the original molded body (excluding end materials) were measured, and the recyclability was evaluated by the difference, ΔYI. The YI value was measured using a chromaticity / turbidity measuring machine COH-300A manufactured by Nippon Denshoku Industries Co., Ltd. In general, the resin is colored yellow by receiving a thermal history. Therefore, the smaller the ΔYI, the better the recyclability.

III Evaluation method for multilayer thermoplastic resin sheet (12) Birefringence of sheet (retardation)
Retardations at 9 points were measured on test pieces cut out from a multilayer thermoplastic resin sheet to 150 mm × 150 mm using an automatic birefringence measuring apparatus ADR-130N manufactured by Oak Manufacturing Co., Ltd. The average value of the measured values was evaluated as birefringence. The smaller the value, the lower the birefringence.
In addition, the total light transmittance and light resistance were evaluated in the same manner as the thermoplastic resin sheet evaluation method.

IV. Evaluation Method for Backlight Type Light Guide Plate A thermoplastic resin sheet prepared by adding a light diffusing agent was cut out to obtain a thermoplastic resin sheet for a light guide plate.
In addition, the total light transmittance, haze, saturated water absorption, and light resistance were evaluated in the same manner as the thermoplastic resin sheet evaluation method.

V Lens Unit Evaluation Method An ultraviolet curable urethane resin was applied to 50 to 150 [mu] m using a dispenser on a mold for preparing a Fresnel lens that had been pre-chrome plated. Subsequently, the thermoplastic resin sheet was pressure-laminated so that air would not enter from above the resin filled in the mold. The ultraviolet curable urethane resin was cured by irradiating ultraviolet rays using a high pressure mercury lamp, and then released to obtain a Fresnel lens unit. The adhesion of the obtained Fresnel lens was evaluated by the following method.

(13) Adhesiveness A grid (10 × 10) was put in a 1 mm width with a knife in a cured ultraviolet curable urethane resin, and a cellophane tape was attached. When the cellophane tape was peeled off, the number of grids (cured resin) peeled from the thermoplastic resin sheet was counted. The case of zero was A, the case of 10 to 10 was B, and the case of 11 or more was C. If it is A, there is no problem, but B is a practical limit. In C, peeling may occur at the time of production, and the reliability of quality during long-term use is lacking, so that it cannot be used.
In addition, light resistance was evaluated similarly to the evaluation method of a thermoplastic resin sheet.

VI Evaluation Method of Injection Molded Light Guide Plate (14) Transferability of Cavity Shape The prism surface of the molded light guide plate was observed with an optical microscope, and those with defects such as sink marks, scratches and roughness were regarded as defective products. Of the 100 light guide plates produced, A was used when there were no defective products, B was used when there were 1 to 10 defective products, and C was used when there were 11 or more defective products.

(15) Uniformity of emitted light Using a molded piece judged as a non-defective product in the above evaluation, a white polyester reflector is laid on the lower side of the concavo-convex pattern forming surface, a cold cathode tube is arranged at the thick end, and the surface A light emitting device was produced. A luminance meter was installed at a position 30 cm above the uneven pattern non-forming surface side, and the luminance was measured. Nine different points were measured, and the emitted light uniformity was evaluated based on the difference between the maximum and minimum luminances.
VII Plastic Lens Evaluation Method (16) Cavity Shape Transferability The molded plastic lens was observed with an optical microscope, and defectives such as sink marks, surface depressions, and roughness were regarded as defective products. Of the 100 discs produced, A was the case where there was no defective product, B was the case where there were 1-10 defective products, and C was the case where there were 11 or more defective products.
VIII Optical Recording Medium Substrate Evaluation Method (17) Cavity Shape Transferability The molded disk was observed with an optical microscope, and defectives such as sink marks, surface dents, and roughness were regarded as defective products. Of the 100 discs produced, A was the case where there was no defective product, B was the case where there were 1-10 defective products, and C was the case where there were 11 or more defective products.
(18) Heat resistance After holding the disk at 80 ° C. for 24 hours, the same observation as in the transferability evaluation was performed once again. The case where the microstructure was maintained was evaluated as A, and the case where even one defect was observed was evaluated as C.

Production Example 1 Production of Copolymer Methyl methacrylate 59.9 mol% and styrene 39.9 mol% as monomer components, and 2.1 × 10 ⁻³ mol% t-amylperoxy 2-ethylhexa as a polymerization initiator A monomer composition comprising noate was continuously fed at a rate of 1 kg / hour to a 10 liter complete mixing vessel equipped with a helical ribbon blade, and continuous polymerization was carried out at an average residence time of 2.5 hours and a polymerization temperature of 150 ° C.

The polymerization liquid is drawn out from the bottom with a gear pump so that the polymerization tank liquid level is constant, and while maintaining at 150 ° C., it is introduced into an extruder equipped with a vent port to devolatilize and extrude into a strand, Cutting into pellets (resin A1). At this time, the molar ratio (A / B) of the structural units in the copolymer was 1.5.
The NMR chart of the obtained resin A1 is shown in FIG. A strong signal derived from the protons of the aromatic ring is seen from 6.5 to 7.3 ppm. Moreover, 16.4 mg of Resin A1 was dissolved in 15 mL of chloroform, and the absorbance measured at 260 nm was 1.093.

Example 1 Thermoplastic transparent resin The resin A1 was dissolved in dioxane to prepare a 10 wt% dioxane solution. A 1000 mL autoclave was charged with 500 parts by weight of a 10 wt% dioxane solution and 1 part by weight of 10 wt% Pd / C (manufactured by NE Chemcat), and the hydrogenation reaction was carried out by maintaining the hydrogen pressure at 10 MPa at 200 ° C. for 15 hours. After removing the catalyst with a filter, dioxane was distilled off by heating to concentrate the reaction solution to 50 wt%. Dilution to 10 wt% with toluene was repeated to replace the solvent to obtain a 50 wt% toluene solution. This was again introduced into an extruder equipped with a vent port to volatilize volatile components, extruded into a strand, and cut to obtain a thermoplastic transparent resin pellet (resin A2). The hydrogenation reaction rate was 96%.
The NMR chart of Resin A2 is shown in FIG. The strong signal derived from the protons of the aromatic ring from 6.5 to 7.3 ppm of the resin A1 shown in FIG. 2 shows that the area was greatly reduced in FIG. 3 and the aromatic double bond was hydrogenated. ing. Further, 62.5 mg of Resin A2 was dissolved in 5 mL of chloroform, and the absorbance measured at 260 nm was 0.521. From the absorbance of the resin A1 at 260 nm and the concentration of the measurement sample, the hydrogenation rate was calculated to be 96%.
The thermal decomposition resistance of Resin A2 was measured. The results are shown in Table 1. Moreover, various test pieces were produced at a cylinder temperature of 260 ° C. by an injection molding machine (FANUC AUTOSHOT100B) using the resin A2, and the glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated. The results are shown in Table 1.

Example 2 Thermoplastic Transparent Resin A thermoplastic transparent resin having a different hydrogenation rate (hydrogenation rate 72%, resin A3) was obtained in the same manner as in Example 1 except that the hydrogenation reaction time of resin A1 was shortened to 10 hours. Obtained. Using resin A3, in the same manner as in Example 1, the heat decomposability, the glass transition temperature, the total light transmittance, the bending strength, and the bending elastic modulus were evaluated. The results are shown in Table 1.

Comparative Example 1 Copolymer Characteristics Resin A1 was used in the same manner as in Example 1 to evaluate thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus. The results are shown in Table 2.

Comparative Example 2 Thermoplastic Resin Thermoplastic resins having different hydrogenation rates (hydrogenation rate 52%, resin A4) were obtained in the same manner as in Example 1 except that the hydrogenation reaction time of resin A1 was shortened to 3 hours. . Resin A4 was used, and the thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Production Example 2 Production of Copolymer A copolymer was synthesized in the same manner as in Production Example 1 except that 80.0 mol% methyl methacrylate and 19.8 mol% styrene were used as monomer components (Resin B1). The molar ratio (A / B) of the structural units in the copolymer was 4.0.

Example 3 Thermoplastic transparent resin A thermoplastic transparent resin was obtained by a hydrogenation reaction in the same manner as in Example 1 except that the resin B1 was used (resin B2). The hydrogenation rate was 100%. Resin B2 was used and evaluated in the same manner as in Example 1 for thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus. The results are shown in Table 1.

Example 4 Thermoplastic Transparent Resin A thermoplastic transparent resin having a different hydrogenation rate (hydrogenation rate 76%, resin B3) in the same manner as in Example 3 except that the hydrogenation time of the resin B1 was reduced to 3 hours. Got. Using resin B3, the thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 Copolymer Characteristics Resin B1 was used in the same manner as in Example 1 to evaluate thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus. The results are shown in Table 2.

Comparative Example 4 Thermoplastic Resin Thermoplastic resins having different hydrogenation rates (hydrogenation rate 45%, resin B4) in the same manner as in Example 3 except that the time for the hydrogenation reaction of resin B1 was shortened to 1.5 hours. Got. Using resin B4, in the same manner as in Example 1, the thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated. The results are shown in Table 2.

Production Example 3 Production of Copolymer A copolymer was produced in the same manner as in Production Example 1 except that 50.7 mol% methyl methacrylate, 9.3 mol% methyl acrylate, and 39.8 mol% styrene were used as monomer components. Was synthesized (resin C1). The molar ratio (A / B) of the structural units in the copolymer was 1.6.

Example 5 Thermoplastic transparent resin A thermoplastic transparent resin was obtained by a hydrogenation reaction in the same manner as in Example 1 except that the resin C1 was used (resin C2). The hydrogenation rate was 97%. Resin C2 was used and evaluated in the same manner as in Example 1 for thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus. The results are shown in Table 1.

Example 6 Thermoplastic Transparent Resin A thermoplastic transparent resin having a different hydrogenation rate (hydrogenation rate 72%, resin C3) was obtained in the same manner as in Example 5 except that the hydrogenation reaction time of the resin C1 was shortened to 3 hours. Obtained. Using resin C3, the thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 5 Copolymer Physical Properties Resin C1 was used in the same manner as in Example 1 to evaluate thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus. The results are shown in Table 2.

Comparative Example 6 Thermoplastic Resin A thermoplastic resin having a different hydrogenation rate (hydrogenation rate 50%, resin C4) was obtained in the same manner as in Example 5 except that the hydrogenation reaction time of the resin C1 was reduced to 1.5 hours. Obtained. Resin C4 was used, and the thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Production Example 4 Physical Properties of Copolymer A copolymer was synthesized in the same manner as in Production Example 1 except that 20.4 mol% methyl methacrylate and 79.4 mol% styrene were used as monomer components (Resin D1). The molar ratio (A / B) of the structural units in the copolymer was 0.25.

Comparative Example 7 Thermoplastic Resin A hydrogenation reaction was performed in the same manner as in Example 1 except that the resin D1 was used (resin D2). The hydrogenation rate was 95%. Resin D2 was used, and the thermal decomposition resistance, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 8 Thermoplastic Resin A thermoplastic resin having a different hydrogenation rate (hydrogenation rate: 76%, resin D3) was obtained in the same manner as in Comparative Example 7 except that the hydrogenation reaction time of the resin D1 was shortened to 3 hours. . Using the resin D3, the heat decomposability, glass transition temperature, total light transmittance, bending strength, and bending elastic modulus were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 7 Thermoplastic resin sheet Using a resin extruder A2 and a 65 mm diameter sheet extruder equipped with a T-die, a 2.0 mm thick single layer sheet was produced at a resin temperature of 265 ° C. Rate, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 3.

Example 8 Thermoplastic resin sheet Using the resin A3, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 3.

Example 9 Thermoplastic resin sheet Using the resin B2, a 2.0 mm thick sheet was prepared in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 3.

Example 10 Thermoplastic resin sheet Using the resin B3, a 2.0 mm thick sheet was prepared in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 3.

Example 11 Thermoplastic resin sheet Using the resin C2, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 3.

Example 12 Thermoplastic resin sheet Using the resin C3, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 3.

Comparative Example 9 Thermoplastic Resin Sheet Using the resin A1, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 10 Thermoplastic Resin Sheet Using resin A4, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 11 Thermoplastic Resin Sheet Using the resin B1, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 12 Thermoplastic Resin Sheet Using resin B4, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 13 Thermoplastic Resin Sheet Using the resin C1, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 14 Thermoplastic resin sheet Using the resin C4, a 2.0 mm thick sheet was prepared in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 15 Thermoplastic Resin Sheet Using the resin D1, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Comparative Example 16 Thermoplastic Resin Sheet Using the resin D2, a 2.0 mm thick sheet was produced in the same manner as in Example 7, and the total light transmittance, saturated water absorption, light resistance, and surface hardness were evaluated. The results are shown in Table 4.

Example 13 Recycled Thermoplastic Resin Sheet In the same manner as in Example 7, a 2.0 mm thick sheet was formed using the resin A2. After crushing the discharged end material at this time into a flaky shape, 10% by weight of the end material is mixed (dry blended) with respect to the total of the resin A2 and the end material, and a 2.0 mm thick sheet (recycled molded product) Was molded. Table 5 shows the results obtained by measuring the recyclability (ΔYI) of the obtained sheet.

Example 14 Recycled Thermoplastic Resin Sheet A 2.0 mm thick sheet (recycled molded product) was molded in the same manner as in Example 7 except that resin B2 was used instead of resin A2, and the recyclability (ΔYI) was evaluated. . The results are shown in Table 5.

Example 15 Recycled Thermoplastic Resin Sheet A 2.0 mm thick sheet (recycled molded product) was molded in the same manner as in Example 7 except that the resin C2 was used instead of the resin A2, and the recyclability (ΔYI) was evaluated. . The results are shown in Table 5.

Comparative Example 17 Recycled Thermoplastic Resin Sheet A 2.0 mm thick sheet (recycled molded product) was molded in the same manner as in Example 7 except that the resin A1 was used instead of the resin A2, and the recyclability (ΔYI) was evaluated. . The results are shown in Table 5.

Comparative Example 18 Recycled Thermoplastic Resin Sheet A 2.0 mm thick sheet (recycled molded product) was molded in the same manner as in Example 7 except that resin B1 was used instead of resin A2, and the recyclability (ΔYI) was evaluated. . The results are shown in Table 5.

Comparative Example 19 Recycled Thermoplastic Resin Sheet A 2.0 mm thick sheet (recycled molded product) was formed in the same manner as in Example 7 except that the resin C1 was used instead of the resin A2, and the recyclability (ΔYI) was evaluated. . The results are shown in Table 5.

Example 16 Multi-layer thermoplastic resin sheet A 65 mm diameter sheet single screw main extruder equipped with a T-die, a 30 mm diameter single screw sub-extruder, a transfer roll, and an extruder formed of a winding device were used. A multilayer sheet was created. MS resin (manufactured by Nippon Steel Chemical Co., Ltd .: Estyrene MS200) is extruded as a core layer resin from a single screw main extruder (barrel temperature 250 ° C.) at a discharge rate of 20 kg / hr, and a single screw sub extruder (barrel temperature 250). ° C) as a skin layer resin, resin A2 is extruded at a discharge rate of 2 kg / h to form skin layers on both sides of the core layer, and the total thickness is 2.0 mm (core layer 1.8 mm, skin layer 0.1 mm) Two types and three layers of multilayer sheets were formed. Using the obtained multilayer sheet, total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6.

Example 17 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the resin A3 was used as the skin layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6.

Example 18 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the resin B2 was used as the skin layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6.

Example 19 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the resin C2 was used as the skin layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6.

Comparative Example 20 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the resin A1 was used as the skin layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6.

Comparative Example 21 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the resin A4 was used as the skin layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6.

Comparative Example 22 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the resin D2 was used as the skin layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. The results are shown in Table 6. At the time of manufacturing this multi-layer sheet, problems such as a part of the edge being cut when the sheet was cut occurred.

Comparative Example 23 Multilayer Thermoplastic Resin Sheet A multilayer sheet was prepared in the same manner as in Example 16 except that the same MS resin was used as the skin layer resin and the core layer resin, and the total light transmittance, light resistance, and birefringence were evaluated. did. The results are shown in Table 6.

Example 20 Backlight-type light guide plate 0.6 parts by weight of siloxane cross-linked light diffusing fine particles (average particle size 2 μm, refractive index 1.43) is blended with 100 parts of pellets of resin A2, Then, a 2.0 mm thick thermoplastic resin sheet was prepared and cut out to obtain a thermoplastic resin sheet for a backlight type light guide plate. Table 7 shows the results of evaluating the total light transmittance, haze, saturated water absorption, and light resistance.

Example 21 Backlight type light guide plate A thermoplastic resin sheet for a backlight type light guide plate was prepared in the same manner except that the resin used in Example 20 was changed to Resin A3, and the total light transmittance, haze, saturated water absorption rate were obtained. Table 7 shows the results of evaluating the light resistance.

Example 22 Backlight type light guide plate A thermoplastic resin sheet for a backlight type light guide plate was prepared in the same manner except that the resin used in Example 20 was changed to the resin B2, and the total light transmittance, haze, saturated water absorption rate were prepared. Table 7 shows the results of evaluating the light resistance.

Example 23 Backlight type light guide plate A thermoplastic resin sheet for a backlight type light guide plate was prepared in the same manner except that the resin used in Example 20 was changed to the resin C2, and the total light transmittance, haze, saturated water absorption rate were prepared. Table 7 shows the results of evaluating the light resistance.

Comparative Example 24 Backlight type light guide plate The resin used in Example 20 was changed to resin A1, and the light diffusing fine particles were changed to siloxane crosslinked light diffusing fine particles having a refractive index of 1.46 and a particle diameter of 2 μm. Table 7 shows the results of preparing a thermoplastic resin sheet and evaluating the total light transmittance, haze, saturated water absorption, and light resistance.

Comparative Example 25 Backlight Type Light Guide Plate A thermoplastic resin sheet was prepared in the same manner except that the resin used in Example 20 was changed to resin B1, and the total light transmittance, haze, saturated water absorption rate, and light resistance were evaluated. The results are shown in Table 7.

Comparative Example 26 Backlight-type light guide plate The resin used in Example 20 was changed to resin C1, and the light diffusing fine particles were changed to siloxane crosslinked light diffusing fine particles having a refractive index of 1.46 and a particle size of 2 μm. Table 7 shows the results of preparing a thermoplastic resin sheet and evaluating the total light transmittance, haze, saturated water absorption, and light resistance.

Comparative Example 27 Backlight-type light guide plate A thermoplastic resin sheet was prepared in the same manner except that the resin used in Example 20 was replaced with commercially available PMMA (Kuraray Co., Ltd. EH-1000S). Table 7 shows the results of evaluating haze, saturated water absorption, and light resistance.

Example 24 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Example 16. Table 8 shows the results of evaluation of light resistance and adhesion.

Example 25 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Example 17. Table 8 shows the results of evaluation of light resistance and adhesion.

Example 26 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Example 18. Table 8 shows the results of evaluation of light resistance and adhesion.

Example 27 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Example 19. Table 8 shows the results of evaluation of light resistance and adhesion.

Comparative Example 28 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Comparative Example 20. Table 8 shows the results of evaluation of light resistance and adhesion.

Comparative Example 29 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Comparative Example 21. Table 8 shows the results of evaluation of light resistance and adhesion.

Comparative Example 30 Lens Unit A lens unit was produced using the multilayer thermoplastic resin sheet produced in Comparative Example 22. Table 8 shows the results of evaluation of light resistance and adhesion.

Example 28 Front Panel The resin sheets obtained in Examples 7 to 12 were cut out and used as they were as the front panel of a projection television. As shown in Table 3, it is possible to produce a front panel which is hard to be damaged due to high surface hardness in any sheet, has little warpage due to water absorption, and does not cause uneven color of the image. did it.

Examples 29 to 34 Injection molding light guide plate Using an injection molding machine (manufactured by FANUC, AUTOSHOT 100B), the resin temperature is 290 ° C., the width is 40 mm, the length is 60 mm, the thin portion is 0.7 mm, and the thick portion is 1.0 mm. A light guide plate having a wedge-shaped cross section formed by forming a prism-shaped uneven pattern on the surface was formed. The prism shape was a pitch of 200 μm and a depth of 5 μm. The light guide plate was manufactured while changing various molding conditions, the state of the mirror surface opposite to the prism surface was visually observed, and the transferability and emitted light uniformity were evaluated as good products without sink or silver. The results are shown in Table 9.

Examples 35 to 40 Plastic Lens Using an injection molding machine (manufactured by FANUC, AUTOSHOT 100B), at a resin temperature of 260 ° C. and a mold temperature of 100 ° C., an optical effective diameter of 2.8 mm, a minimum thickness of 0.45 mm, and a thickness on the optical axis A biconvex lens having a thickness of 1.8 mm was molded. The transferability of the obtained plastic lens was evaluated. The results are shown in Table 10.

Examples 41 to 46 Optical Recording Medium Substrate Using an injection molding machine (manufactured by FANUC, AUTOSHOOT 100B), a 120 mm DVD mold (stamper groove depth: 160 nm, stamper groove pitch: 0.80 μm), thickness 0.6 mm Disc (optical recording medium substrate) was prepared. Transferability and heat resistance were evaluated. The results are shown in Table 11.

The thermogravimetric decrease curve obtained by thermal decomposition resistance evaluation of Example 1 of this invention and Comparative Example 1 is shown. The NMR chart of resin A1 manufactured by manufacture example 1 is shown. The NMR chart of resin A2 manufactured in Example 1 is shown.

Claims (4)

The core layer made of a resin having a benzene ring, and which is formed on one surface or both surfaces of the core layer, coextruded multilayer thermoplastic resin sheet comprising a skin layer consisting of the following resin (X).
Resin (X): a structural unit (B) obtained by polymerizing a monomer composition containing at least one (meth) acrylic acid ester monomer and at least one aromatic vinyl monomer, and derived from an aromatic vinyl monomer Obtained by hydrogenating 70% or more of the aromatic double bond of the copolymer whose molar ratio (A / B) of the structural unit (A mole) derived from the (meth) acrylic acid ester monomer to (mol) is 1-4. A thermoplastic transparent resin characterized by that. A backlight type light guide plate comprising the thermoplastic resin sheet according to claim 1 . A lens unit comprising a substrate comprising the thermoplastic resin sheet according to claim 1 and at least one type of lens formed on one or both sides of the substrate. A display front panel comprising the thermoplastic resin sheet according to claim 1 .

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