JP2010150557A - Scratch resistant resin plate and display window protective plate for personal digital assistant using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scratch resistant resin plate suitable to a protective plate for a displaying window of a portable information terminal. <P>SOLUTION: A cured film on a methacrylic resin plate is formed by a curable paint containing a compound with at least six (meth)acryloyloxy groups in the molecule and a compound containing four or five (meth)acryloyloxy groups in the molecule or a compound with at least seven (meth)acryloyloxy groups and a compound with 3 to 6 (meth)acryloyloxy groups in the molecule. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a scratch-resistant resin plate suitable as a display window protective plate for a portable information terminal, and a display window protective plate for a portable information terminal using the same.

  In recent years, portable telephones such as cellular phones and PHS (Personal Handy-phone System) have become popular with the Internet, and in addition to simple voice transmission functions, portable information terminals have a function to display text information and image information. Has been widely spread as. In addition to such portable telephones, PDAs (Personal Digital Assistants) that have functions such as an address book as well as Internet functions and e-mail functions are also widely used. In this specification, such mobile phones, PHS, PDAs, and the like are collectively referred to as “portable information terminals”. That is, the “portable information terminal” in the present specification is a generic name for a device that has a window (display) for displaying character information, image information, and the like that is large enough to be carried by a person.

  These portable information terminals display character information and image information by a method such as liquid crystal or EL (electroluminescence). The display window is made of a transparent resin as a protective plate. In general, methacrylic resin plates are preferably used from the viewpoint of transparency (see, for example, Patent Documents 1 to 3). In order to prevent scratches on the surface of the protective plate, it has been proposed to provide a scratch-resistant (hard coat) cured film with a curable coating. A compound having at least two (meth) acryloyloxy groups, that is, a compound containing a polyfunctional (meth) acrylate is mainly studied (see the patent document).

Japanese Patent Laid-Open No. 2002-6676 JP 2004-143365 A JP 2004-299199 A

  Conventionally proposed display window protection plates for portable information terminals are not yet sufficient in the scratch resistance of the cured coating. Therefore, the present inventors have conducted intensive research to provide a scratch-resistant resin plate suitable as a display window protection plate for a portable information terminal provided with a cured film having high scratch resistance. As a result, the methacrylic resin plate And found that a desired scratch-resistant resin plate can be obtained by forming a cured film on the surface of the film using a curable paint containing a plurality of kinds of polyfunctional (meth) acrylates. It came to do.

  That is, the present invention includes a compound having at least 7 (meth) acryloyloxy groups in the molecule and a compound having 3 to 6 (meth) acryloyloxy groups in the molecule on the surface of the methacrylic resin plate. It is an object of the present invention to provide a scratch-resistant resin plate characterized in that a cured film is formed from a curable coating.

  Furthermore, according to the present invention, there is also provided a display window protection plate for a portable information terminal made of these scratch-resistant resin plates.

  The scratch-resistant resin plate of the present invention has a cured film having high scratch resistance. By using this scratch-resistant resin plate as a display window protection plate for a portable information terminal, the display window can be effectively used. Can be protected.

  The scratch-resistant resin plate of the present invention comprises a methacrylic resin plate as a substrate and a cured film formed on the surface thereof. The methacrylic resin constituting this substrate is a polymer mainly composed of methacrylic acid ester, and may be a homopolymer of methacrylic acid ester, 50% by weight or more of methacrylic acid ester, and other monomer 50 It may be a copolymer with a weight percent or less. In the case of a copolymer, the proportion of the methacrylic acid ester in all the monomers is preferably 70% by weight or more, and more preferably 90% by weight or more. As the methacrylate ester, alkyl methacrylate is preferably used, and methyl methacrylate is particularly preferably used. Examples of monomers other than methacrylic acid esters include acrylic acid esters such as methyl acrylate and ethyl acrylate, aromatic alkenyl compounds such as styrene and methyl styrene, and unsaturated carboxylic acids such as acrylic acid and methacrylic acid. And alkenyl cyanide compounds such as acrylonitrile and methacrylonitrile.

  The methacrylic resin plate may have a flat surface like a normal plate (sheet) or film, or may have a curved surface like a convex lens or a concave lens. . Further, a fine structure such as fine irregularities may be provided on the surface.

  The methacrylic resin plate may be colored with a dye or a pigment, if necessary, or may contain an antioxidant, an ultraviolet absorber, rubber particles, or the like. The thickness of the methacrylic resin plate is preferably 0.1 mm or more and 3.0 mm or less.

  A scratch-resistant cured film is formed on at least one surface of the methacrylic resin plate. In one embodiment of the present invention, at least 6 (metabolites) are used as the curable compound in order to form this cured film. ) A curable coating containing a compound having an acryloyloxy group and a compound having 4 or 5 (meth) acryloyloxy groups in the molecule [hereinafter sometimes referred to as a curable coating (A)] is used. In another embodiment of the present invention, the curable compound has at least 7 (meth) acryloyloxy groups in the molecule and 3 to 6 (meth) acryloyloxy groups in the molecule. A curable coating containing a compound [hereinafter sometimes referred to as curable coating (B)] is used. By using such a curable paint containing a plurality of types of polyfunctional (meth) acrylates, a cured film having high scratch resistance can be formed.

  In the present specification, the (meth) acryloyloxy group means an acryloyloxy group or a methacryloyloxy group, and “(meth)” in the case of (meth) acrylate, (meth) acrylic acid, etc. is the same. Meaning.

  Examples of the polyfunctional (meth) acrylates that can be contained in the curable paints (A) to (B) are compounds having at least 7 (meth) acryloyloxy groups in the molecule, and 6 (meta) in the molecule. ) When divided into compounds having an acryloyloxy group, compounds having 4 or 5 (meth) acryloyloxy groups in the molecule, and compounds having 3 (meth) acryloyloxy groups in the molecule, Examples of the compound having at least 7 (meth) acryloyloxy groups in the molecule include tripentaerythritol hepta (meth) acrylate, tripentaerythritol octa (meth) acrylate, and the like, Examples of compounds having a (meth) acryloyloxy group include dipentaerythritol hexa (meth) acrylate. DOO, etc. tripentaerythritol hexa (meth) acrylate.

  Examples of compounds having 4 or 5 (meth) acryloyloxy groups in the molecule include pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth) acrylate. Examples of compounds having three (meth) acryloyloxy groups in the molecule include glycerin tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, Examples include tris [(meth) acryloyloxyethyl] isocyanurate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, and the like.

  Further, a urethane (meth) acrylate compound obtained by a reaction between a compound having m isocyanato groups in the molecule and a compound having hydroxyl groups and n (meth) acryloyloxy groups in the molecule, m An ester (meth) acrylate compound obtained by a reaction between a compound having one halocarbonyl group and a compound having a hydroxyl group and n (meth) acryloyloxy groups in the molecule is converted into m × n ( Examples of the compound having a (meth) acryloyloxy group can be given.

  In the curable coating (A), the ratio of the compound having at least 6 (meth) acryloyloxy groups and the compound having 4 or 5 (meth) acryloyloxy groups in the molecule is the total amount of both. Based on 100 parts by weight, the former is usually 5 to 95 parts by weight and the latter is 95 to 5 parts by weight, preferably 30 to 70 parts by weight for the former and 70 to 30 parts by weight for the latter. In addition, the curable coating (A) may include a curable compound other than the above, for example, a compound having three (meth) acryloyloxy groups in the molecule, as exemplified above, or ethylene as necessary. Two (meth) acryloyloxy groups in the molecule, such as glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate Although the compound which has it may be contained, the quantity is 20 parts weight or less normally with respect to 100 weight part of said both total amounts.

  In the curable coating (B), the ratio of the compound having at least 7 (meth) acryloyloxy groups and the compound having 3 to 6 (meth) acryloyloxy groups in the molecule is the sum of both. Based on the amount of 100 parts by weight, the former is usually 5 to 95 parts by weight and the latter is 95 to 5 parts by weight, preferably 30 to 70 parts by weight for the former and 70 to 30 parts by weight for the latter. The curable paint (B) also contains a curable compound other than the above, for example, a compound having two (meth) acryloyloxy groups in the molecule as exemplified above, if necessary. However, the amount is usually 20 parts by weight or less with respect to 100 parts by weight of the total amount of both.

  The curable coating material may contain conductive fine particles as necessary. By containing the conductive fine particles, a cured film having antistatic performance and antistatic performance can be formed.

  Examples of the conductive fine particles include metal oxides such as antimony oxide, indium / tin composite oxide (ITO), tin / antimony composite oxide (ATO), antimony / zinc composite oxide, and doping with phosphorus. And fine particles such as tin oxide.

  The conductive fine particles preferably have a particle size of 0.001 to 0.1 μm. When the particle size is too small, industrial production is difficult, and when the particle size is too large, the transparency of the cured film is lowered, which is not preferable. Moreover, it is preferable that the usage-amount of electroconductive fine particles is 1-100 weight part with respect to 100 weight part of curable compounds. If the amount used is too small, a sufficient antistatic effect cannot be obtained, and if it is too large, the scratch resistance of the cured film is lowered or the film formability is lowered.

  In addition, the curable paint may contain a solvent in order to adjust the viscosity, the thickness of the cured film, and the like. Examples of the solvent include methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol, 2-butanol (sec-butyl alcohol), 2-methyl-1-propanol (isobutyl alcohol), 2 Alcohols such as methyl-2-propanol (tert-butyl alcohol), 2-ethoxyethanol, 2-butoxyethanol, 3-methoxy-1-propanol, 1-methoxy-2-propanol, 1-ethoxy-2- Alkoxy alcohols such as propanol, ketols such as diacetone alcohol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, aromatic hydrocarbons such as toluene, xylene, ethyl acetate, butyl acetate, etc. D Such as ethers, and the like. The amount of the solvent used is appropriately adjusted according to the substrate material, shape, coating method, desired thickness of the cured film, etc., but usually the total amount of the curable compound and the conductive fine particles used as necessary. The amount is about 20 to 10,000 parts by weight with respect to 100 parts by weight.

  Furthermore, the curable paint (A) or (B) may contain additives such as a stabilizer, an antioxidant, a colorant, and a leveling agent as necessary. By containing the leveling agent, the smoothness and scratch resistance of the cured film can be improved.

  As the leveling agent, silicone oil is preferably used. Examples thereof include dimethyl silicone oil, phenylmethyl silicone oil, alkyl / aralkyl modified silicone oil, fluorosilicone oil, polyether modified silicone oil, fatty acid ester modified silicone oil, methyl Hydrogen silicone oil, silanol group-containing silicone oil, alkoxy group-containing silicone oil, phenol group-containing silicone oil, methacryl-modified silicone oil, amino-modified silicone oil, carboxylic acid-modified silicone oil, carbinol-modified silicone oil, epoxy-modified silicone oil, mercapto Examples include modified silicone oil, fluorine-modified silicone oil, and polyether-modified silicone oil. These silicone oils may be used alone or in combination of two or more.

  The usage-amount of a silicone oil is 0.01-20 weight part normally with respect to 100 weight part of total amounts of a sclerosing | hardenable compound and the electroconductive fine particles used as needed. If the amount used is too small, it is difficult to obtain the intended effect, and if it is too large, the strength of the cured film is lowered, which is not preferable.

  After applying the curable coating described above to the surface of the methacrylic resin plate, it is dried if necessary, and then the formed coating film is cured to cure the surface of the methacrylic resin plate with high scratch resistance. A film can be formed.

  The curable coating can be applied by a method such as a micro gravure coating method, a roll coating method, a dipping coating method, a spin coating method, a die coating method, a cast transfer method, a flow coating method, or a spray coating method.

  The coating film is suitably cured by irradiating with an activation energy ray. Examples of the activation energy rays include electron beams, ultraviolet rays, and visible rays, and are appropriately selected according to the type of curable compound. In the case where ultraviolet rays or visible light is used as the activation energy ray, a photopolymerization initiator is usually used.

  Examples of the photopolymerization initiator include acetophenone, acetophenone benzyl ketal, anthraquinone, 1- (4-isopropylphenyl-2-hydroxy-2-methylpropan-1-one, carbazole, xanthone, 4-chlorobenzophenone, 4,4 '-Diaminobenzophenone, 1,1-dimethoxydeoxybenzoin, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2,2-dimethoxy-2-phenylacetophenone, 1- (4-dodecylphenyl) -2-hydroxy 2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, triphenylamine, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 1-hydroxy Chlohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, fluorenone, fluorene, benzaldehyde, benzoin ethyl ether, benzoisopropyl ether, benzophenone, Michler's ketone, 3-methylacetophenone, 3,3 ′, 4,4′-tetra-tert-butylperoxycarbonylbenzophenone (BTTB), 2- (dimethylamino) -1- [4- (morpholinyl) phenyl] -2- (phenylmethyl) -1-butanone, 4-benzoyl -4'-methyldiphenyl sulfide, benzyl and the like.

  The photopolymerization initiator may be used in combination with a dye sensitizer. Examples of the dye sensitizer include xanthene, thioxanthene, coumarin, and ketocoumarin. Examples of the combination of the photopolymerization initiator and the dye sensitizer include a combination of BTTB and xanthene, a combination of BTTB and thioxanthene, a combination of BTTB and coumarin, and a combination of BTTB and ketocoumarin.

Since said photoinitiator is marketed, such a commercial item can be used.
Examples of commercially available photopolymerization initiators include “IRGACURE 651”, “IRGACURE 184”, “IRGACURE 500”, “IRGACURE 1000”, “IRGACURE 2959”, sold by Ciba Specialty Chemicals, Inc., respectively. “DAROCUR 1173”, “IRGACURE 907”, “IRGACURE 369”, “IRGACURE 1700”, “IRGACURE 1800”, “IRGACURE 819”, and “IRGACURE 784”, respectively, “KAYACURE” sold by Nippon Kayaku Co., Ltd. “ITX”, “KAYACURE DETX-S”, “KAYACURE BP-100”, “KAYACURE BMS”, “KAYACURE 2-EAQ”, etc. It is.

  When using a photoinitiator, the usage-amount is 0.1 weight part or more normally with respect to 100 weight part of curable compounds. If the amount used is too small, the curing rate tends not to increase as compared with the case where no photopolymerization initiator is used. In addition, the upper limit of the usage-amount of a photoinitiator is about 10 weight part normally with respect to 100 weight part of curable compounds.

  Moreover, the intensity | strength and irradiation time of an activation energy ray are suitably adjusted according to the kind of curable compound, the thickness of the coating film, etc. The activation energy ray may be irradiated in an inert gas atmosphere, and as this inert gas, nitrogen gas, argon gas, or the like can be used.

  The thickness of the cured film thus formed is preferably 1 to 10 μm, more preferably 2 to 6 μm. If the thickness is too small, the scratch resistance may be insufficient, and if it is too large, cracks are likely to occur when exposed to high temperature and high humidity. The thickness of the cured coating can be adjusted by adjusting the amount per area of the curable coating applied to the surface of the methacrylic resin plate and the concentration of the solid content contained in the curable coating.

  The scratch-resistant resin plate of the present invention thus obtained has a cured film with high scratch resistance formed on the surface of a methacrylic resin plate, and is used as a display window protection plate for portable information terminals typified by mobile phones. It can be used suitably. Further, it can be used as various members in fields where scratch resistance is required, such as a finder portion of a digital camera or a handheld video camera, or a display window protection plate of a portable game machine.

  In order to produce a display window protection plate for a portable information terminal from the scratch-resistant resin plate of the present invention, first, if necessary, processing such as printing and drilling may be performed and cut to a required size. After that, if it is set on the display window of the portable information terminal, a display window with high scratch resistance can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

  The thickness of the cured film of the scratch-resistant resin plate obtained in each example was measured using a film thickness measuring device [F-20 from Filmmetrics].

In addition, the scratch resistance of the cured film of the scratch-resistant resin plate obtained in each example was scratched with steel wool # 0000 with a load of 2000 g / 4 cm ² at 10 reciprocations, 150 reciprocations, and 100 reciprocal steps. Were rubbed until visually confirmed, and evaluated by the number of reciprocations.

Example 1
Dipentaerythritol hexaacrylate 50 parts and pentaerythritol tetraacrylate 50 parts as a curable compound, photopolymerization initiator [IRGACURE 184 of Ciba Specialty Chemicals Co., Ltd.], and isobutyl alcohol 125 parts and 1-methoxy- as a solvent A curable coating was prepared by mixing 125 parts of 2-propanol.

This paint was applied to both surfaces of a methacrylic resin plate (Sumitex E, Sumitomo Chemical Co., Ltd.) having a thickness of 2 mm and a size of 100 mm × 60 mm by a dipping coating method, followed by drying at room temperature for 5 minutes and further at 10 ° C. at 10 ° C. The coating film was formed on the surface of the methacrylic resin plate by drying for minutes. Next, the coating film was cured by irradiating with an ultraviolet ray of 0.5 J / cm ² using a 120 W high-pressure mercury lamp to obtain a scratch-resistant resin plate having a cured coating thickness of 2.0 μm. Moreover, the dipping conditions were changed to obtain a scratch-resistant resin plate having a cured coating thickness of 3.1 μm.
The results of evaluating the scratch resistance of these scratch-resistant resin plates are shown in Table 1.

Comparative Example 6
A scratch-resistant resin plate having a cured coating thickness of 1.8 μm, which was operated in the same manner as in Example 1 except that 72 parts of dipentaerythritol hexaacrylate and 28 parts of pentaerythritol tetraacrylate were used as the curable compound. Got. Moreover, the dipping conditions were changed to obtain a scratch-resistant resin plate having a cured coating thickness of 3.1 μm. The results of evaluating the scratch resistance of these scratch-resistant resin plates are shown in Table 1.

Comparative Example 7
A scratch-resistant resin plate having a cured coating thickness of 3.9 μm, which was carried out in the same manner as in Example 1 except that 28 parts of dipentaerythritol hexaacrylate and 72 parts of pentaerythritol tetraacrylate were used as the curable compound. Got. Table 1 shows the results of evaluating the scratch resistance of the scratch-resistant resin plate.

Example 4
A scratch-resistant resin having a cured coating thickness of 3.6 μm, the same operation as in Example 1 except that 50 parts of tripentaerythritol octaacrylate and 50 parts of dipentaerythritol hexaacrylate were used as the curable compound. I got a plate. Table 1 shows the results of evaluating the scratch resistance of the scratch-resistant resin plate.

Example 5
A scratch-resistant resin plate having a cured coating thickness of 3.1 μm, which is the same as in Example 1, except that 50 parts of tripentaerythritol octaacrylate and 50 parts of pentaerythritol tetraacrylate are used as the curable compound. Got. Table 1 shows the results of evaluating the scratch resistance of the scratch-resistant resin plate.

Example 6
A scratch-resistant resin plate having a cured coating thickness of 3.1 μm, the same operation as in Example 1 except that 50 parts of tripentaerythritol octaacrylate and 50 parts of pentaerythritol triacrylate were used as the curable compound. Got. Table 1 shows the results of evaluating the scratch resistance of the scratch-resistant resin plate.

Comparative Example 1
Except for using only 100 parts of dipentaerythritol hexaacrylate as the curable compound, the same operation as in Example 1 was performed to obtain a scratch-resistant resin plate having a cured coating thickness of 3.2 μm. Moreover, the dipping conditions were changed to obtain a scratch-resistant resin plate having a cured coating thickness of 4.5 μm. The results of evaluating the scratch resistance of these scratch-resistant resin plates are shown in Table 1.

Comparative Example 2
Except for using only 100 parts of pentaerythritol tetraacrylate as the curable compound, the same operation as in Example 1 was performed to obtain a scratch-resistant resin plate having a cured coating thickness of 2.7 μm. Moreover, the dipping conditions were changed to obtain a scratch-resistant resin plate having a cured coating thickness of 3.6 μm. The results of evaluating the scratch resistance of these scratch-resistant resin plates are shown in Table 1.

Comparative Example 3
A scratch-resistant resin having a cured coating thickness of 2.7 μm, the same operation as in Example 1 except that 50 parts of dipentaerythritol hexaacrylate and 50 parts of tetraethylene glycol diacrylate were used as the curable compound. I got a plate. Moreover, the dipping conditions were changed to obtain a scratch-resistant resin plate having a cured coating thickness of 5.0 μm. The results of evaluating the scratch resistance of these scratch-resistant resin plates are shown in Table 1.

Comparative Example 4
Except for using only 100 parts of tripentaerythritol octaacrylate as the curable compound, the same operation as in Example 1 was performed to obtain a scratch-resistant resin plate having a cured coating thickness of 4.0 μm. Table 1 shows the results of evaluating the scratch resistance of the scratch-resistant resin plate.

Comparative Example 5
Except for using only 100 parts of pentaerythritol triacrylate as the curable compound, the same operation as in Example 1 was performed to obtain a scratch-resistant resin plate having a cured coating thickness of 3.6 μm. Table 1 shows the results of evaluating the scratch resistance of the scratch-resistant resin plate.

TPEOA: tripentaerythritol octaacrylate DPEHA: dipentaerythritol hexaacrylate PETeA: pentaerythritol tetraacrylate PETrA: pentaerythritol triacrylate TEGDA: tetraethylene glycol diacrylate

Claims (3)

  Cured by a curable coating containing a compound having at least 7 (meth) acryloyloxy groups in the molecule and a compound having 3 to 6 (meth) acryloyloxy groups in the molecule on the surface of the methacrylic resin plate A scratch-resistant resin plate characterized in that a film is formed.   The scratch-resistant resin plate according to claim 1, wherein the thickness of the methacrylic resin plate is 0.1 to 3 mm.   A display window protective plate for a portable information terminal comprising the scratch-resistant resin plate according to claim 1.