JP2008100422A - Resin laminate for covering indicator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin material for covering an indicator which is excellent in pencil hardness, impact resistance, and punching quality even when its thickness is below 0.8 mm as an indicator protecting cover and is inhibited in the occurrence of warpage, a defective appearance, or the like even during printing or vapor deposition processing. <P>SOLUTION: A paint film layer having a thickness of 2-12 μm and being made of an ultraviolet curable resin which contains at least 3 wt.% of an at least bifunctional urethane acrylate compound is laminated on at least one side of an impact resistant acrylic resin sheet having a thickness of 0.35-0.75 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin laminate for a display body cover having a hard coat layer suitable as a display body protection cover for industrial electronic devices such as mobile phones, and more specifically, has excellent pencil hardness, impact resistance, and punching workability. It is related with the resin laminated body for display body covers which has.

  In industrial electronic devices having display bodies such as mobile phones, with the diversification of design, thinning, and large area, there is an increasing demand for thinning the display cover. Generally used acrylic resin sheets and polycarbonate resin sheets are used. In the case of acrylic resin sheet with hard coat, it has excellent pencil hardness, but when punching, it is easy to crack due to impact, especially in punching considering high speed and continuous economic efficiency. The typical minimum thickness is limited to about 0.8 mm. On the other hand, in the case of a polycarbonate resin sheet subjected to a hard coat, since the impact resistance is high and it is not easily broken, and the punching process is easy, the practical minimum thickness is about 0.4 mm. The pencil hardness was low and it was easy to be scratched.

  In order to solve these problems, there has been proposed (Patent Document 1) in which an acrylic resin-based sheet including an acrylic resin layer in which rubber particles are dispersed in a resin component is subjected to a hard coat treatment. However, even with such a sheet, the impact resistance actually decreases when the thickness of the substrate is less than 0.8 mm, and there is a practical problem in dealing with the reduction in thickness. Moreover, the punching workability was not taken into consideration.

  On the other hand, there has been proposed a laminate (Patent Document 2) obtained by laminating an acrylic resin layer on one side of a polycarbonate resin layer and subjecting the acrylic resin layer surface to a hard coat treatment. This laminate has a certain level of impact resistance, pencil hardness, and punchability. However, since the acrylic resin layer on the surface and the polycarbonate resin layer as the base material are laminated together, the front and back are asymmetrical resins. It is a layer structure, and when printing processing or metal deposition processing as a display cover in the next process is performed, it is subject to environmental changes such as temperature and humidity, and it is easy to cause appearance defects due to warpage and peeling of the coating film. There was a problem.

From the above situation, as used in display covers of industrial electronic devices such as mobile phones, it has a thickness of less than 0.8 mm, has excellent pencil hardness, impact resistance, and punching workability. There is a demand for a resin material for a display cover that has improved problems such as warpage and poor appearance.
JP 2004-143365 A JP 2006-103169 A

  The present invention has been made in view of the above-described problems, and has excellent pencil hardness, impact resistance and punching workability even when the thickness is less than 0.8 mm, and at the time of printing and vapor deposition. Another object of the present invention is to provide a resin material for a display body cover that is less likely to warp or have poor appearance.

  As a result of diligent research to achieve the above object, the inventor used an impact-resistant acrylic resin sheet as a base material, and the coating layer made of an ultraviolet curable resin containing a specific urethane acrylate on the sheet surface has a specific thickness. It has been found that the above problem can be solved by laminating.

  That is, the invention according to claim 1 is a coating film comprising an ultraviolet curable resin containing at least 3% by weight of at least a bifunctional urethane acrylate on at least one side of an impact-resistant acrylic resin sheet having a thickness of 0.35 mm to 0.75 mm. The gist is a resin laminate for a display body cover in which layers are laminated at a thickness of 2 to 12 μm.

  The gist of the invention according to claim 2 is the resin laminate for a display body cover according to claim 1, wherein the impact-resistant acrylic resin sheet is produced by a melt extrusion method.

  The gist of the invention according to claim 3 is that the impact-resistant acrylic resin sheet has a glass transition temperature of 90 ° C. or higher. The resin laminate for display body cover according to claim 1 or 2. .

  Moreover, the invention which concerns on Claim 4 WHEREIN: The said ultraviolet curable resin is 3-50 weight% of at least 1 type of bifunctional urethane acrylate, 20-50 weight% of at least 1 type of 4-6 functional acrylate, and at least The summary of the resin laminate for a display body cover according to any one of claims 1 to 3, which contains 3 to 30% by weight of one kind of 1-2 functional acrylate monomer.

  Further, the invention according to claim 5 is characterized in that the bifunctional urethane acrylate has a glass transition temperature of 10 ° C. or lower, and the resin laminate for a display body cover according to any one of claims 1 to 4.

  In the invention according to claim 6, the coating layer has a thickness of 2 to 5 μm on the impact-resistant acrylic resin sheet surface on the display body side, and 5 on the impact-resistant acrylic resin sheet surface on the opposite side of the display body. The summary of the resin laminate for a display body cover according to any one of claims 1 to 5, wherein the resin laminate is laminated with a thickness of -12 μm.

  As described above, the resin laminate for a display cover according to the present invention contains at least one bifunctional urethane acrylate at least 3% by weight on at least one side of an impact-resistant acrylic resin sheet having a thickness of 0.35 mm to 0.75 mm. By laminating a coating film layer made of a mold resin at a thickness of 2 to 12 μm, even if the sheet thickness is less than 0.8 mm, it has excellent pencil hardness, impact resistance and punching workability, In addition, there is an effect that problems such as warping and poor appearance hardly occur during printing and vapor deposition. This is suitably used as a cover material for protecting a display body of an industrial electronic device such as a portable device.

  Moreover, by making the said impact-resistant acrylic resin sheet manufactured by the melt-extrusion method, the obtained resin laminated body for display body covers has good surface smoothness, and is excellent in economical efficiency.

  Moreover, when the impact-resistant acrylic resin sheet has a glass transition temperature of 90 ° C. or higher, when a coating layer made of an ultraviolet ray curable resin is dried and cured, it can be heat-treated at a high temperature. The production efficiency is better, and the obtained resin laminate for a display body cover is more economical.

  Further, the ultraviolet curable resin comprises 3 to 50% by weight of at least one bifunctional urethane acrylate, 20 to 50% by weight of at least one 4 to 6 functional acrylate, and at least one 1 to 2 functional acrylate. By containing the monomer in an amount of 3 to 30% by weight, the balance of pencil hardness, impact resistance, punching workability and the like is particularly good.

  In addition, when the bifunctional urethane acrylate has a glass transition temperature of 10 ° C. or less, impact resistance can be stably secured without being influenced by environmental changes such as temperature. .

  The coating layer is laminated with a thickness of 2 to 5 μm on the impact-resistant acrylic resin sheet surface on the display body side and with a thickness of 5 to 12 μm on the impact-resistant acrylic resin sheet surface on the opposite side of the display body. As a result, it is possible to obtain an excellent balance of pencil hardness, impact resistance, punching workability, and the like, and to reliably prevent warpage due to environmental changes such as temperature and humidity. .

  In order to explain the present invention, each component constituting the ultraviolet curable resin according to the present invention will be described first.

<Bifunctional urethane acrylate>
The bifunctional urethane acrylate used in the present invention is a reaction product of an isocyanate compound obtained by reacting a polyol with a diisocyanate and an acrylate monomer having a hydroxyl group.

  Examples of the polyol include polyester polyol, polyether polyol, and polycarbonate diol. The manufacturing method of a polyester polyol is not specifically limited, A well-known manufacturing method can be employ | adopted. For example, the diol and dicarboxylic acid or dicarboxylic acid chloride may be subjected to a polycondensation reaction, or the diol or dicarboxylic acid may be esterified and subjected to an ester exchange reaction. Examples of the dicarboxylic acid include adipic acid, succinic acid, glutaric acid, pimelic acid, sebacic acid, azelaic acid, maleic acid, terephthalic acid, isophthalic acid, and phthalic acid. As the diol, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol or the like is used. Examples of the polyether polyol include polyethylene oxide, polypropylene oxide, and ethylene oxide-propylene oxide random copolymerization. Examples of the polycarbonate diol include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, polyoxyethylene glycol, and the like are used, and one kind or two kinds You may use the above together.

  As the diisocyanate, linear or cyclic aliphatic diisocyanate or aromatic diisocyanate is used. Typical examples of linear or cyclic aliphatic diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylylene diisocyanate. Examples of the aromatic diisocyanate include tolylene diisocyanate and xylylene diisocyanate.

  Examples of the acrylate monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, and polyethylene glycol monoacrylate.

<4-6 functional acrylate>
As the 4-6 functional acrylate used in the present invention, urethane acrylate, epoxy acrylate, polyester acrylate and the like can be used.

  The epoxy acrylate can be obtained, for example, by an esterification reaction between an oxirane ring of a low molecular weight bisphenol type epoxy resin or a novolac epoxy resin and acrylic acid. Moreover, as polyester acrylate, it is obtained by esterifying the hydroxyl group of the polyester which has a hydroxyl group in the both ends obtained by condensation of polyhydric carboxylic acid and a polyhydric alcohol with acrylic acid, for example. Alternatively, it can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with acrylic acid.

  Of these, urethane acrylate is most preferable. This is because, together with the hardness required for a hard coat, more excellent wear resistance and scratch resistance can be obtained. Moreover, it is because the curing shrinkage is relatively small compared with other polyfunctional acrylates while realizing performance as a hard coat film layer such as hardness and abrasion resistance.

  Urethane acrylate is a reaction product of an isocyanate compound obtained by reacting a polyol and diisocyanate and an acrylate monomer having a hydroxyl group, and examples of the polyol include polyester polyol, polyether polyol, and polycarbonate diol.

  The manufacturing method of the said polyester polyol is not specifically limited, A well-known manufacturing method can be employ | adopted. For example, the diol and dicarboxylic acid or dicarboxylic acid chloride may be subjected to a polycondensation reaction, or the diol or dicarboxylic acid may be esterified and subjected to an ester exchange reaction. Examples of the dicarboxylic acid include adipic acid, succinic acid, glutaric acid, pimelic acid, sebacic acid, azelaic acid, maleic acid, terephthalic acid, isophthalic acid, and phthalic acid. Examples of the diol include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, and tetrapropylene glycol.

  The polyether polyol is preferably a polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide random copolymer having a number average molecular weight of less than 600. If it is 600 or more, the cured product may be too soft and hard coat performance may not be obtained.

  Examples of the polycarbonate diol include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, polyoxyethylene glycol, and the like are used, and one kind or two kinds You may use the above together.

  As the diisocyanate, a linear or cyclic aliphatic diisocyanate is used. Of course, aromatic diisocyanates can also be used, and it is possible to easily obtain excellent hard coat properties such as hardness and scratch resistance. On the other hand, polyfunctional oligomers are the main components that form the hard coat skeleton. This is because when the component is used, the light resistance is lowered, and yellowing easily occurs upon exposure to light, so that the function as a transparent hard coat is impaired in practical use. Typical examples of linear or cyclic aliphatic diisocyanates include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylylene diisocyanate.

  Examples of acrylate monomers having a hydroxyl group include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, Examples include polyethylene glycol monoacrylate.

  In addition, examples of the 4- to 6-functional acrylate that can be used in the present invention include dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, and the like.

<1-2 functional acrylate monomer>
Examples of the 1-2 functional acrylate used in the present invention include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, polyethylene glycol monoacrylate, acryloylmorpholine, N-vinylpyrrolidone, N vinylformamide, isobornyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated hydrogenated bisphenol A diacrylate, ethoxylated cyclohesane dimethanol diacrylate, tricyclodecane dimethanol di Acrylate can be mentioned.

  The ultraviolet curable resin according to the present invention is constituted by using one or all of the components described above. In the present invention, 3% by weight of the bifunctional urethane acrylate is included in the ultraviolet curable resin. It is necessary to be contained and configured. By doing so, the coating layer made of this ultraviolet curable resin can be given appropriate flexibility while maintaining the surface hardness, and the obtained resin laminate for the display body cover has pencil hardness and impact resistance. It becomes possible to achieve both sexes. On the other hand, when the content of the bifunctional urethane acrylate is less than 3% by weight of the ultraviolet curable resin composition, the effect cannot be obtained.

  Furthermore, in the present invention, the ultraviolet curable resin is 3 to 50% by weight of at least one bifunctional urethane acrylate, 20 to 50% by weight of at least one 4 to 6 functional acrylate, and at least one 1 It is preferable to comprise 3 to 30% by weight of a bifunctional acrylate monomer. By such composition distribution, the balance of pencil hardness, impact resistance, punching workability, etc. is good, and it is more preferable as a display body protective cover for industrial electronic devices such as mobile phones. At this time, if the content of the bifunctional urethane acrylate is less than 3% by weight, the content is too small, so that the effect of improving the impact resistance and punching processability cannot be obtained, and if the ratio exceeds 50% by weight, the pencil hardness decreases. Too much. Further, when the content of the 4-6 functional acrylate is less than 20% by weight, the desired pencil hardness cannot be obtained, and when it exceeds 50% by weight, impact resistance and punching workability are deteriorated. When the content of the 1-2 functional acrylate monomer is less than 3% by weight, it becomes difficult to obtain the adhesion between the coating layer and the substrate. When the content exceeds 30% by weight, the appearance of the coating film deteriorates and the pencil hardness decreases. Be looked at.

  Furthermore, the glass transition temperature of the bifunctional urethane acrylate used in the present invention is preferably 10 ° C. or lower. By carrying out like this, the obtained laminated body is hard to be influenced by environmental changes, such as temperature, and can ensure impact resistance more stably. On the other hand, when the glass transition temperature is 10 ° C. or higher, the impact resistance cannot be ensured stably and sufficiently.

  The glass transition temperature of the bifunctional urethane acrylate can be mainly adjusted by the type of polyol used, the molecular weight, and the combination thereof, and it is also an auxiliary adjustment depending on the type of diisocyanate to be combined and the type of acrylate monomer having a hydroxyl group. Is possible.

  The component constituting the ultraviolet curable resin in the present invention may include a trifunctional or hexafunctional polyfunctional acrylate, or an oligomer or polymer having no reactivity, in addition to the component in the present invention. is not.

  The ultraviolet curable resin in the present invention is applied to at least one side of an impact-resistant acrylic resin sheet and cured by ultraviolet irradiation to form a hard coat coating layer. At that time, a photopolymerization initiator, a diluted solution of an organic solvent, and the like are added to the composition.

  The photopolymerization initiator has a function as a polymerization initiator when the photopolymerizable compound is cured by ultraviolet rays, and a known one can be used alone or in combination, such as benzoin, benzoin methyl ether, Benzoin or benzoin alkyl ethers such as benzoin ethyl ether and benzoin isopropyl ether, aromatic ketones such as benzophenone and benzoylbenzoic acid, alpha-dicarbonyls such as benzyl, benzyl ketals such as benzyldimethyl ketal and benzyl diethyl ketal, Acetophenone, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propan-1-one , 1- Acetophenones such as 4-isopropylphenyl) -2-hydroxy-2-methyl-propan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 2-methyl Anthraquinones such as anthraquinone, 2-ethylanthraquinone and 2-t-butylanthraquinone, thioxanthones such as 2,4-dimethylthioxanthone, 2-isopropylthioxanthone and 2,4-diisopropylthioxanthone, bis (2,4,6-trimethyl) Phosphine oxides such as benzoyl) -phenylphosphine oxide, alpha-acyloximes such as 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, ethyl p-dimethylaminobenzoate, p-Dimethylaminobenzoic acid It can be used amines such as isoamyl.

  Moreover, in order to obtain an excellent coating film appearance, it is preferable that a surface conditioner such as a fluorine type or a modified silicone type is added to the paint. As the fluorine-based or modified silicone-based surface conditioner, polyether-based, alkyl-based, or polyester-based ones can be used, but polyether-based is particularly preferable. An acrylic copolymer can also be used as a surface conditioner. These surface conditioners can also be used in combination.

  In addition, for the purpose of imparting antistatic performance, relaxation of internal stress due to curing shrinkage of the coating film, imparting specific irregularities to the surface, absorption and reflection of specific wavelengths such as ultraviolet rays and infrared rays, imparting design properties, etc. If necessary, inorganic and / or organic fillers can be mixed into the ultraviolet curable resin of the present invention.

  The resin component is applied to the impact-resistant acrylic resin sheet as a base material after being diluted and dissolved with an organic solvent as necessary to obtain a coating liquid. Commercially available organic solvents can be used, such as aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, ethanol, propanol and butanol, methyl ethyl ketone, 2 -Use of ketones such as pentanone and isophorone, esters such as ethyl acetate, butyl acetate and methoxypropyl acetate, cellosolve solvents such as ethyl cellosolve, and glycol solvents such as methoxypropanol, ethoxypropanol and methoxybutanol alone or in combination it can. The viscosity and resin concentration of the coating liquid can be appropriately selected according to the situation, purpose, and application method.

  The impact-resistant acrylic resin sheet of the present invention is obtained by molding an impact-resistant acrylic resin into a sheet shape. As the impact-resistant acrylic resin, those obtained by imparting impact resistance to a methacrylic resin, or publicly known Commercial products produced by the method can be used. As the methacrylic resin, a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and another copolymerizable comonomer is applied. Examples of the copolymerizable comonomer include acrylic acid esters such as methyl acrylate and butyl acrylate, aromatic vinyl compounds such as styrene, vinylcyan compounds such as acrylonitrile, and the like.

  As a method for imparting impact resistance to a methacrylic resin, it is common to disperse rubber particles in the methacrylic resin. As the rubber particles, acrylic rubber, butadiene rubber, styrene-butadiene rubber, etc. can be used. For the intended use of the present invention, acrylic rubber has transparency and hardness. From the standpoint of balance of physical properties such as impact resistance. Examples of the acrylic rubber particles include those having a single layer structure made of an elastic polymer mainly composed of alkyl acrylate such as butyl acrylate, and inner layers made of a hard polymer mainly composed of methyl methacrylate. Known acrylic rubber particles such as those having a multilayer structure in which an outer layer made of an elastic polymer mainly composed of an alkyl acrylate such as butyl acrylate is provided can be used. Those in which a small amount of a crosslinkable polyfunctional monomer is copolymerized with an elastic polymer can also be used.

The type and ratio of the copolymer compound, the component and average particle diameter of the rubber particles, and the amount added thereof can be selected as appropriate, and are not particularly limited. The total light transmittance is 90% or more (JIS K7361-1), the haze value is 0.7% or less (JIS K7136), the hardness is 60 or more in Rockwell hardness (JIS K7202 / M scale), As the impact resistance, it is desirable to select a Charpy impact value of 2.5 kJ / m ² or more (JIS K7111 / notched). Further, as the heat resistance, a glass transition temperature of 90 ° C. or higher is particularly desirable. When the glass transition temperature is 90 ° C or higher, the base material can be heated to about 80 ° C when the UV curable resin is applied as a paint and dried and cured, so that the coating properties of the UV curable resin are extremely improved. It is because it can do.

  In dispersing the rubber particles in the methacrylic resin, various additives such as ultraviolet absorbers, organic dyes, pigments, inorganic dyes, antioxidants, antistatic agents, surfactants, and the like are added as necessary. You may mix | blend.

  As a method for producing the impact-resistant acrylic resin sheet used in the present invention, various known methods such as a melt casting method, a melt extrusion method such as a T-die method and an inflation method, and a calendar method can be used. However, it is preferable that it is manufactured by the melt extrusion method. As the melt extrusion method, an impact-resistant acrylic resin is melt-kneaded using an extruder, extruded through a T-die, and the molten sheet material is rolled and cooled by a cooling roll to make the surface temperature uniform, and draw. The method of manufacturing by taking up with a take-off roll is mentioned. The specifications of the extruder are not particularly limited, but a single screw extruder or a different-direction twin screw extruder is particularly suitable. As the rolling method, a method in which the impact-resistant acrylic resin is melt-extruded from a T-die and at least both surfaces of the obtained sheet-like material are brought into contact with a roll or a belt is preferable in that a sheet having good surface properties can be obtained.

  The resin laminate for a display cover according to the present invention can be obtained by diluting the ultraviolet curable resin with a solvent to obtain a curable coating, and applying, drying and curing the impact resistant acrylic resin sheet.

  The curable paint can be applied to the impact-resistant acrylic resin sheet using a known method such as a roll coater, a flow coater, a spray coater, a curtain flow coater, a dip coater, or a slit die coater. be able to. A simultaneous or sequential method can be used as the coating method on both sides.

  The coating layer thickness of the curable coating applied to the impact-resistant acrylic resin sheet is set so that the thickness of the coating layer when dried is in the range of 2 to 12 μm. When the thickness is less than 2 μm, sufficient pencil hardness cannot be obtained, and when the thickness exceeds 12 μm, impact resistance, punching workability and the like are deteriorated.

  In the present invention, the curable coating is preferably applied to both sides of the impact-resistant acrylic resin sheet, and in this case, the surface on the display body side has a thickness of 2 to 5 μm when the coating layer is dried. Further, it is more preferable that the surface on the opposite side of the display body has a thickness of 5 to 12 μm when the coating layer is dried. By doing so, it becomes possible for the obtained resin laminate for a display body cover to obtain a better balance between pencil hardness, impact resistance, punching workability, and the like. Further, the occurrence of warping can be surely prevented even by environmental changes such as humidity and temperature.

  The curable paint obtained by diluting the ultraviolet curable resin with a solvent is applied to the impact-resistant acrylic resin sheet, and then the atmospheric temperature is raised to 50 ° C. or higher, desirably 80 ° C. or higher, and the diluted solvent is sufficiently evaporated. In the heated state, ultraviolet rays are irradiated to cure the coating film. Here, the degree of curing can be quantified by measuring the remaining amount of reactive groups by infrared absorption analysis, as is widely known. For the ultraviolet irradiation, a general electroded or electrodeless high-pressure mercury lamp or metal halide lamp can be used. Of course, a low voltage electron beam irradiation apparatus of about 100 keV can also be used. When an electron beam is used as the curing means, a polymerization initiator as exemplified above is not necessary.

  The resin laminate for display body cover thus obtained is suitably used as a protective cover for information display sections such as monitors for portable devices, household electrical appliances, industrial electronic devices, automotive electronic devices, etc. Required as a protective cover (1) Pencil hardness (JIS K5600) is 2H or higher, preferably 3H or higher. (2) As impact resistance, a 30g steel ball must be dropped from a height of 1m and not cracked. , (3) As a workability, punching is possible, (4) As a stability at the time of printing and vapor deposition, there is no requirement for appearance defects such as warping after high temperature heating (80 ° C. × 15 minutes). It will be satisfactory.

  Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto.

<Examples 1 and 2>
As an impact-resistant acrylic resin, an impact-resistant methacrylic resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumipex HT55X) was used, melted and kneaded with an extruder (manufactured by Toshiba Machine Co., Ltd., 65 mm diameter single screw extruder), and then passed through a T die The sheet-like product was extruded and rolled with cooling so that both surfaces were completely in contact with the polishing roll, and an impact-resistant acrylic resin sheet having a thickness of 0.5 mm was obtained.

  On the other hand, bifunctional urethane acrylate [trade name: Ebecryl 8411, manufactured by Daicel Cytec Co., Ltd.], hexafunctional acrylate [aliphatic isocyanate-based hexafunctional acrylate, trade name: Ebecryl 1290, Daicel Cytec Co., Ltd.] Product], 6-functional acrylate [dipentaerythritol hexaacrylate], and 2-functional acrylate monomer [1,6-hexanediol diacrylate], and these components are blended as shown in Table 1 to form an ultraviolet curable resin. Got.

  The ultraviolet curable resin is diluted with a polar diluent 1-methoxy-2-propanol so that the amount is 20% by weight in the solution, and a photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, trade name: Irgacure 184 (manufactured by Ciba Specialty Chemicals) was added so that the solid content ratio was 4% by weight with respect to the total amount of the diluted solution to prepare a curable coating.

  The curable coating was sufficiently mixed with stirring, and then applied to one side of the impact-resistant acrylic resin sheet using a metal bar coater so that the thickness of the coating layer when dried was 5 μm.

  Next, the impact-resistant acrylic resin sheet coated with the curable coating material is placed in a hot air circulation oven at 80 ° C. and dried for 10 minutes, and then a 160 W / cm metal halide lamp (manufactured by Ushio Electric Co., Ltd.) is used. Then, ultraviolet rays were irradiated to sufficiently cure the curable paint, and a resin laminate for a display body cover was produced. In addition, the irradiation method at this time was performed by moving on the conveyor at a speed of 6.0 m / min while keeping the distance between the metal halide lamp and the coating layer at 9 cm.

  About the obtained resin laminated body for display body covers, various physical properties were measured and evaluated by the following evaluation methods. The results are shown in Table 1.

<Measurement and evaluation of various physical properties>
<Appearance>
The coating film in the resin laminated body for display body cover was observed visually, and the following evaluation was performed.
When the coating surface was smooth and transparent from any angle, it was judged as good (◯), and when the coating surface was rough or when it was cloudy when viewed from the front, it was judged as poor (x).
<Pencil hardness>
Based on JIS K 5600, the measurement was performed under a load of 750 g.
<Impact resistance>
A sample sheet obtained by cutting a resin laminate for a display body cover into a size of 60 mm × 60 mm is fixed on a table having a 45 mm × 35 mm window open, and a steel ball having a weight of 30 g toward the sample sheet in the window portion. Was dropped from a height of 100 cm, and the presence or absence of cracks in the sheet was confirmed.
<Punching workability>
Using a punching die equipped with a Thomson blade with a vertical and horizontal length of 91 mm x 54 mm and a corner R of 3.0 mm, the display body cover resin laminate was punched with a press machine. The state of occurrence was observed. A case where no cracks or burrs were generated on the surface was considered good.
<Curl / War>
A sample sheet obtained by cutting the resin laminate for a display body cover into a size of 100 mm × 100 mm was placed on a flat plate, and the maximum value of the distance between the flat plate and the sample was visually measured and evaluated as follows.
Particularly good when the distance between the flat plate and the sample sheet is less than 1.0 mm (◯), good when the distance between the flat plate and the sample is 1.0 mm or more and less than 2.0 mm (Δ), and the distance between the flat plate and the sample is 2 Those with a thickness of 0 mm or more were regarded as defective (x).
<Heat-resistant deformation>
A sample sheet obtained by cutting a resin laminate for a display body cover to a size of 100 mm × 100 mm is placed in an oven and left for 15 minutes in an environment of 80 ° C., then the sample is placed on a flat plate, and the distance between the flat plate and the sample The maximum value of was measured visually and evaluated as follows.
Particularly good when the distance between the flat plate and the sample sheet is less than 1.0 mm (◯), good when the distance between the flat plate and the sample is 1.0 mm or more and less than 2.0 mm (Δ), and the distance between the flat plate and the sample is 2 Those with a thickness of 0 mm or more were regarded as defective (x).
<Coating film adhesion>
After immersing the display laminate cover resin laminate in boiling water for 60 minutes, wiping off the moisture and drying at room temperature for 2 hours or more, a cross-cut tape peeling test (conforming to JIS K5600) is performed as follows. Evaluated.
The case where no peeling is observed in 25 of 25 squares is considered to have a very strong adhesion (○), and the case where any of the squares peels is regarded as a practical problem. Defective (x).

<Example 3>
Using the same ultraviolet curable resin as in Example 1 and using a metal bar coater, except that the coating layer was applied to a thickness of 3 μm when dried, the same as in Example 1, A resin laminate for a display cover was prepared. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are shown in Table 1.

<Example 4>
Using the same ultraviolet curable resin as in Example 1 and using a metal bar coater, except that the coating layer was applied to a thickness of 10 μm when dried, the same as in Example 1, A resin laminate for a display cover was prepared. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are shown in Table 1.

<Examples 5-7>
As a component constituting the ultraviolet curable resin, polyfunctional urethane acrylate [trade name: Unidic 17-806, manufactured by Dainippon Ink & Chemicals, Inc.] was used instead of the hexafunctional acrylate and the bifunctional acrylate monomer in Example 1. A resin laminate for a display body cover was produced in the same manner as in Example 1 except that it was blended as shown in Table 1. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are shown in Table 1.

<Examples 8 to 10>
As a component constituting the ultraviolet curable resin, polyfunctional urethane acrylate [trade name: SN-5X 3623, manufactured by San Nopco Co., Ltd.] is used instead of the hexafunctional acrylate and bifunctional acrylate monomer in Example 1, and the results are shown in Table 1. A resin laminate for a display body cover was produced in the same manner as in Example 1 except that it was blended as described above. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are shown in Table 1.

<Comparative Example 1>
A resin laminate for a display cover is obtained in the same manner as in Example 1 except that the hexafunctional acrylate and the bifunctional acrylate monomer in Example 1 are blended as shown in Table 2 as the components constituting the ultraviolet curable resin. Produced. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are shown in Table 2.

<Comparative example 2>
Instead of the bifunctional urethane acrylate, hexafunctional acrylate, and bifunctional acrylate monomer in Example 1, as a component constituting the ultraviolet curable resin, a polyfunctional urethane acrylate [trade name: Unidic 17-806, Dainippon Ink & Chemicals, Inc. Kogyo Kogyo Co., Ltd.] was used, and 50 parts of this polyfunctional urethane acrylate was mixed with 150 parts of 1-methoxy-2-propanol as a solvent to prepare a curable paint, and the same as in Example 1. Then, a resin laminate for a display body cover was produced. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are also shown in Table 2.

<Comparative Example 3>
As a component constituting the ultraviolet curable resin, in place of the bifunctional urethane acrylate, hexafunctional acrylate, and bifunctional acrylate monomer in Example 1, only polyfunctional urethane acrylate [trade name: SN-5X 3623, manufactured by San Nopco] For the display cover, in the same manner as in Example 1 except that 50 parts of this polyfunctional urethane acrylate was mixed with 150 parts of 1-methoxy-2-propanol as a solvent to prepare a curable paint. A resin laminate was produced. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are also shown in Table 2.

<Comparative Example 4>
Using the same ultraviolet curable resin as in Example 1 and using a metal bar coater, except that the coating layer was applied to a thickness of 15 μm when dried, the same as in Example 1, A resin laminate for a display cover was prepared. About the obtained resin laminated body for display body covers, the measurement and evaluation of various physical properties were performed by the same evaluation method as Example 1. The results are also shown in Table 2.

  As apparent from Table 1, in Examples 1 to 10 according to the present invention, even when the sheet thickness is less than 0.8 mm, the appearance, pencil hardness, impact resistance, punching workability, curl / warp, It turns out that it is excellent in all the evaluation items of heat-resistant deformation property and coating-film adhesiveness. On the other hand, in Comparative Examples 1-4 which deviate from this invention in Table 2, it was inferior to either of the said evaluation items. Thus, it can be seen that the resin laminate for display body cover shown in the examples of the present invention is suitably used as a cover material for protecting the display body of industrial electronic devices such as portable devices.

Claims (6)

  At least one surface of an impact-resistant acrylic resin sheet having a thickness of 0.35 mm to 0.75 mm is coated with a coating layer made of an ultraviolet curable resin containing at least 3% by weight of a bifunctional urethane acrylate at a thickness of 2 to 12 μm. Laminated resin laminate for display cover.   The resin laminate for a display body cover according to claim 1, wherein the impact-resistant acrylic resin sheet is produced by a melt extrusion method.   The resin laminate for a display body cover according to claim 1, wherein the impact-resistant acrylic resin sheet has a glass transition temperature of 90 ° C. or higher.   The UV curable resin comprises 3 to 50% by weight of at least one bifunctional urethane acrylate, 20 to 50% by weight of at least one type of 4 to 6 functional acrylate, and at least one type of 1 to 2 functional acrylate monomer. The resin laminated body for display body covers in any one of Claims 1-3 containing 3-30 weight%.   The resin laminate for a display body cover according to any one of claims 1 to 4, wherein the bifunctional urethane acrylate has a glass transition temperature of 10 ° C or lower.   The said coating-film layer was laminated | stacked with the thickness of 2-5 micrometers on the surface used as the display body side of an impact-resistant acrylic resin sheet, and the thickness of 5-12 micrometers on the surface used as the other side of a display body, respectively. The resin laminate for a display body cover according to any one of 5.