JP5317406B2 - Adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive tape usable for fixing a liquid crystal display module unit and a back-light unit of LCD and exhibiting the functions of reflectivity and light-shielding property within a thickness range meeting the demand of thin and light-weight LCD. <P>SOLUTION: The adhesive tape is composed of a substrate and an adhesive layer formed on at least one surface of the substrate. The substrate has layers colored in white color, a color other than white and black colors and black color in the order. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an adhesive tape. The pressure-sensitive adhesive tape of the present invention has a function of reflecting light and shielding light of a specific wavelength, and in a lighting / external light type liquid crystal display device (LCD) suitable for mobile phones and PDA applications, etc. It is useful as an adhesive tape for fixing the liquid crystal display module unit and the backlight unit.

  As shown in FIG. 6, a lighting / external light type LCD used for a mobile phone or the like has a liquid crystal display module unit and a backlight unit fixed with an adhesive tape. The pressure-sensitive adhesive tape is required to have light reflectivity and light shielding properties with respect to a specific wavelength. The purpose of reflectivity is to reduce the power consumption by reflecting the light of the backlight to increase the brightness and efficiently using the reflected light. On the other hand, the light shielding property is intended to suppress the occurrence of poor visual recognition due to backlight light leaking to the LCD surface.

  Conventionally, pressure-sensitive adhesive tapes that have both reflectivity and light shielding properties have been studied. In general, the pressure-sensitive adhesive tape is provided with a colored layer on one side of a base film or a colored pressure-sensitive adhesive layer. In order to reflect the light of the backlight, a white layer is generally disposed on the backlight side, and a black layer is generally disposed on the liquid crystal display module side in order to shield the backlight from being leaked. For example, in an adhesive tape using a white base film colored white, a transparent adhesive layer is provided on the backlight side, and a black colored layer or a black colored adhesive layer is provided on the liquid crystal display module side. Yes. In addition, in a pressure-sensitive adhesive tape using a black base film colored black, a white colored layer on the backlight side or a white-colored pressure-sensitive adhesive layer is provided with a transparent pressure-sensitive adhesive layer on the liquid crystal display module side. Tape is provided. Moreover, in the pressure-sensitive adhesive tape using the transparent substrate film, the white colored layer or the white colored adhesive layer on the backlight side, the black colored layer or the black colored adhesive layer on the liquid crystal display module side. Is provided.

  However, in order to achieve both light reflectivity and light-shielding properties with the adhesive tape, each colored layer must be stacked or thickened. As a result, there has been a problem that the total thickness of the adhesive tape is increased, making it impossible to cope with thin and light mobile phones.

  The present invention is an adhesive tape that can be used for fixing a liquid crystal display module unit and a backlight unit in an LCD, and can exhibit reflective and light-shielding functions within a thickness range that can be reduced in thickness and weight. An object is to provide an adhesive tape.

It is another object of the present invention to provide a liquid crystal display device in which a liquid crystal display module unit and a backlight unit are fixed by the adhesive tape .

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the adhesive tape shown below, and have come to solve the present invention.

That is, the present invention relates to a liquid crystal display module unit and a pressure-sensitive adhesive tape having reflectivity and light shielding properties used for fixing a backlight unit, wherein the pressure-sensitive adhesive tape comprises a base material and an adhesive on at least one side of the base material. The present invention relates to a pressure-sensitive adhesive tape having reflectivity and light-shielding property, wherein the base material has a support base material and a colored layer, and the thickness of the pressure-sensitive adhesive layer is 10 to 50 μm .

In the pressure-sensitive adhesive tape of the present invention, since the thickness of the pressure-sensitive adhesive layer is 10 to 50 μm , the pressure- sensitive adhesive tape is used for fixing the liquid crystal display module unit and the backlight unit in the lighting / external light type LCD. , it is possible to reduce the total thickness of the pressure-sensitive adhesive tape can be applied to a thinner and lighter.

As said adhesive tape, it is preferable that the thickness of the said colored layer is 1-10 micrometers.

Moreover, as said adhesive tape, it is preferable that the said support base material is a polyethylene terephthalate.

In the pressure-sensitive adhesive tape, the support substrate preferably has a thickness of 4 to 70 μm .

In the pressure-sensitive adhesive tape, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive, and the acrylic pressure-sensitive adhesive is a homopolymer of an alkyl (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms. Or a copolymer of the above (meth) acrylic acid alkyl ester and a copolymerizable monomer such as another functional monomer as a base polymer, and in the total copolymer monomer component constituting the base polymer, the (meth) The acrylic acid alkyl ester is preferably contained in an amount of 50% by weight or more, and the acrylic pressure-sensitive adhesive preferably contains a tackifier resin and a crosslinking agent in addition to the base polymer.

  The present invention also relates to a liquid crystal display module unit and a liquid crystal display device in which a backlight unit is fixed by the adhesive tape.

  The adhesive tape of the present invention will be described below with reference to the drawings. The pressure-sensitive adhesive tape of the present invention has a base material 1 and a pressure-sensitive adhesive layer 2 on at least one side of the base material 1. In FIG. 1, the adhesive layer 2 is provided on both surfaces of the substrate 1. The substrate 1 has a white layer (hereinafter also referred to as W layer), a color layer other than white and black (hereinafter also referred to as S layer), and a black layer (hereinafter also referred to as B layer) in this order. The pressure-sensitive adhesive tape of the present invention can be used in the form of a sheet.

  In addition, the colored layer of this invention is represented by chromaticity. The chromaticity can be represented by L of L · a · b measured by a chromaticity meter. The white layer (W layer) has a chromaticity measured by a chromaticity meter in a range of L: 92 ± 5, and the black layer (B layer) has a chromaticity measured by a chromaticity meter of L: 25 ± 10. What is in range.

  If the adhesive tape of this invention has the said W layer, S layer, and B layer in this order as the base material 1, there will be no restriction | limiting in particular. For example, as shown to FIGS. 2-5, the base material 1 can illustrate what has the support base material 12 and the colored layer 11. FIG.

  In FIG. 2, an 11W layer, an 11S layer, and an 11B layer are formed in this order as the colored layer 11 from the support base material 12 side. In FIG. 4, an 11B layer, an 11S layer, and an 11W layer are formed in this order as the colored layer 11 from the support base material 12 side. 2 and 4, the support substrate 12 may be a transparent substrate film. That is, if the base material 1 has a W layer, an S layer, and a B layer in this order, the base material 1 may include a transparent layer.

  Moreover, in FIG. 2, it can also be set as the white base film 12W so that the support base material 12 itself may become a W layer. In FIG. 4, it can also be set as the black base film 12B so that the support base material 12 itself may become B layer. That is, if the base material 1 has the W layer, the S layer, and the B layer in this order, each of the W layer, the S layer, and the B layer may be one layer or a plurality of two or more layers. Also good.

  In FIG. 3, the 11S layer and the 11B layer are formed in this order as the colored layer 11 from the support base material 12 side. In FIG. 3, the supporting base material 12 itself is a white base film 12 </ b> W having a W layer. In FIG. 5, the 11S layer and the 11W layer are formed in this order as the colored layer 11 from the support base material 12 side. In FIG. 5, the supporting base material 12 itself is a black base material film 12B which is a B layer.

  In the pressure-sensitive adhesive tape of the present invention, the B layer contributes to light shielding properties, while the W layer contributes to reflectivity. In general, it is generally more difficult to obtain reflectivity from the W layer than to obtain light shielding properties from the B layer. From these, as the pressure-sensitive adhesive tape of the present invention, in the pressure-sensitive adhesive tape as shown in FIG. 2 or FIG. 3, an embodiment in which a white base film 12 </ b> W is used as the support base 12 is preferable.

  In addition, as an aspect of the pressure-sensitive adhesive tape of the present invention other than the above, the support substrate 12 itself is a film 12S colored so as to be an S layer, and an 11B layer is provided as a colored layer on one side, and the other side is provided. The support substrate 12 itself has a W layer, an S layer, and a B layer in this order.

  The material of the support substrate 12 is not particularly limited, and various materials can be used. Examples thereof include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; polyvinyl alcohol and polyvinylidene chloride. Among these, polyesters such as polyethylene terephthalate are preferable in terms of transparency and strength.

  The thickness of the support base 12 is not particularly limited, but is about 4 to 70 μm, preferably 10 to 50 μm, from the viewpoints of thin and light weight and workability. In addition, when making the support base material 12 into a white base film, a black base film, etc., the pigment etc. according to each coloring are mix | blended.

  The colored layer 11 can be formed by applying a compound containing a pigment, a binder, and a solvent on the support substrate 12. As the binder, those used for forming the colored layer can be used without particular limitation. For example, polyurethane, phenol resin, epoxy resin, urea melamine resin, polymethyl methacrylate and the like are exemplified. The solvent is appropriately selected according to the type of pigment and binder. As the pigment, a pigment corresponding to each colored layer of the W layer, the S layer, and the B layer is appropriately selected.

  The thickness of the colored layer 11 is generally about 1 to 10 μm in total thickness. The thickness of each colored layer is usually preferably about 1 to 2 μm. In addition, the formation method of a colored layer can employ | adopt without limitation especially the means conventionally employ | adopted for formation of a colored layer, such as gravure printing, flexographic printing, and offset printing.

  As for the pigment used for coloring the support substrate 12 and the colored layer 11, a white pigment is used for the W layer and a black pigment is used for the B layer. Examples of white pigments include titanium dioxide, zinc white, and lead white. Examples of black pigments include carbon black, acetylene black, pine smoke, and graphite.

  The S layer is not particularly limited as long as it is a color other than white and black. For example, the S layer can be colored silver, blue, red, or the like. Among these, the S layer is preferably silver because it can exhibit light-shielding properties and reflectivity in multiple stages. Examples of silver pigments include aluminum. The S layer preferably has a chromaticity measured by a chromaticity meter in the range of L: 70 ± 10.

  As an adhesive which comprises the adhesive layer 2, various adhesives, such as an acrylic adhesive, a rubber adhesive, and a silicone adhesive, can be used without a restriction | limiting in particular.

  As the acrylic pressure-sensitive adhesive, in particular, a homopolymer of an alkyl group having 1 to 18 carbon atoms (meth) acrylic acid alkyl ester, or a copolymerization property of the above (meth) acrylic acid alkyl ester and other functional monomers. What uses the copolymer with a monomer for a base polymer is used suitably.

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, octyl acrylate, 2-ethyl ester acrylate, isooctyl acrylate, acrylic Illustrative examples include decyl acid, isodecyl acrylate, lauryl acrylate, stearyl acrylate, and corresponding alkyl methacrylates.

  Examples of the functional monomer include a monomer having a hydroxyl group, a monomer having a carboxyl group, and a monomer having an amide group. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate. Monomers having a carboxyl group include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; maleic acid monoalkyl esters such as butyl maleate; unsaturated compounds such as maleic acid, fumaric acid and itaconic acid Examples of the dibasic acid anhydride include dibasic acid anhydrides such as maleic anhydride. Examples of the monomer having an amide group include acrylamide, dimethyl (meth) acrylamide, alkyl (meth) acrylamide such as diethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide and the like. Examples thereof include alkoxymethyl (meth) acrylamide and diacetone (meth) acrylamide. Examples of the monomer having an amino group include dimethylaminoethyl (meth) acrylate. As copolymerizable monomers other than those described above, vinyl acetate, styrene, α-methylstyrene, vinyl chloride, acrylonitrile, ethylene, propylene, and the like can also be used.

  In order to produce a copolymer of (meth) acrylic acid alkyl ester, it is preferable that 50% by weight or more of (meth) acrylic acid alkyl ester is contained in all copolymerization monomer components. When the proportion of the (meth) acrylic acid alkyl ester is less than 50% by weight, the pressure-sensitive adhesive may not exhibit sufficient tackiness. The ratio of the (meth) acrylic acid alkyl ester is more preferably 60% by weight or more.

  Moreover, in addition to a base polymer, a tackifier, a crosslinking agent, etc. are mix | blended with said adhesives, such as an acrylic adhesive, as needed. Examples of tackifiers include rosin resins, polyterpene resins, coumarone-indene resins, petroleum resins, and terpene-phenol resins. Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent.

  Rubber-based adhesives include rubber elastic materials such as natural rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, polyisoprene, polybutene, polyisobutylene, and ethylene-vinyl acetate copolymer. Examples include polymers. For the rubber elastic body, for example, an appropriate amount of a tackifier such as rosin resin, polyterpene resin, coumarone-indene resin, petroleum resin, terpene-phenol resin, and liquid polybutene, mineral oil, liquid poly Softeners such as isoprene and liquid polyacrylate are blended. As the silicone-based pressure-sensitive adhesive, one having polydimethylsiloxane as a main component is used.

  In addition, an appropriate amount of various additives such as an anti-aging agent such as butylhydroxytoluene can be added to the adhesive.

  The pressure-sensitive adhesive layer 2 can be formed by forming it on one side or both sides of the substrate 1. The method for forming the pressure-sensitive adhesive layer 2 is not particularly limited, and is a method in which a solution or emulsion containing a pressure-sensitive adhesive is directly applied to the substrate 1 using a comma coater, top feed reverse coater or the like, and dried. After forming the pressure-sensitive adhesive layer 2 on the mold film, a method of bonding them to the substrate 1 can be employed.

The thickness of the adhesive layer 2, a pressure-sensitive adhesive tape, in the liquid crystal display device applied to a cellular phone or the like, for use as an adhesive tape for fixing a liquid crystal display module unit and a backlight unit, in terms of thickness and weight reduction 10 to 50 μm.

  The pressure-sensitive adhesive layer 2 is usually transparent, but can be colored white or black. That is, in the base material 1, the pressure-sensitive adhesive layer 2 on the W layer side can be colored white, and the pressure-sensitive adhesive layer 2 on the B layer side can be colored black.

  A separator is provided on the pressure-sensitive adhesive layer 2 as necessary. Examples of the constituent material of the separator include paper, synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate. The surface of the separator may be subjected to mold release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc., if necessary, in order to improve the peelability from the pressure-sensitive adhesive layer. The thickness of a separator is 10-200 micrometers normally, Preferably it is about 25-100 micrometers.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement of chromaticity was performed on a chromaticity meter CR-200 manufactured by Minolta.

Example 1
White (chromaticity L: 92), silver (chromaticity L: 75), black (chromaticity L: 75) as a colored layer on one side of a white substrate film (polyethylene terephthalate, chromaticity L: 92) having a thickness of 38 μm. A film on which three layers were printed in the order of 25) was used as a substrate. NB-500 manufactured by Dainichi Seika Kogyo Co., Ltd. was used as the ink used for printing the colored layer. The thickness of each layer of the colored layer was 1 μm. A transparent acrylic pressure-sensitive adhesive was applied to both sides of the substrate and dried to obtain a double-sided pressure-sensitive adhesive tape provided with an adhesive layer having a thickness of 20 μm.

Example 2
On one side of a white substrate film (polyethylene terephthalate, chromaticity L: 92) having a thickness of 38 μm, as a colored layer, silver (chromaticity L: 75), black (chromaticity L: 25), black (chromaticity L: A film on which three layers were printed in the order of 25) was used as a substrate. NB-500 manufactured by Dainichi Seika Kogyo Co., Ltd. was used as the ink used for printing the colored layer. The thickness of each layer of the colored layer was 1 μm. A transparent acrylic pressure-sensitive adhesive was applied to both sides of the substrate and dried to obtain a double-sided pressure-sensitive adhesive tape provided with an adhesive layer having a thickness of 20 μm.

Comparative Example 1
A film obtained by printing a black layer (chromaticity L: 25) as a colored layer on one side of a white substrate film (polyethylene terephthalate, chromaticity L: 92) having a thickness of 38 μm was used as a substrate. NB-500 manufactured by Dainichi Seika Kogyo Co., Ltd. was used as the ink used for printing the colored layer. The thickness of the colored layer was 1 μm. A transparent acrylic pressure-sensitive adhesive was applied to both sides of the substrate and dried to obtain a double-sided pressure-sensitive adhesive tape provided with an adhesive layer having a thickness of 20 μm.

Comparative Example 2
A white substrate film (polyethylene terephthalate, chromaticity L: 92) having a thickness of 38 μm was used as the substrate. A transparent acrylic pressure-sensitive adhesive was applied to one side of the substrate and dried to provide an adhesive layer having a thickness of 20 μm. On the other side, an acrylic pressure-sensitive adhesive colored in black with a black pigment mixed with the acrylic adhesive was applied, dried, and a black adhesive layer having a thickness of 20 μm (chromaticity L: 25) and a double-sided pressure-sensitive adhesive tape was obtained.

  About the double-sided adhesive tape obtained by the said Example and comparative example, it tested on the following conditions. Measured from the white side of the adhesive tape. The results are shown in Table 1.

(Transmittance)
The transmittance in the wavelength region of 550 nm was measured using an integrating sphere type spectral transmittance measuring device manufactured by Murakami Color Research Laboratory.

(Reflectance)
Using a spectrophotometer manufactured by Shimadzu Corporation, the diffuse reflectance in the 550 nm wavelength region was measured.

  It is recognized that the reflectance of the adhesive tape of the example is improved as compared with the adhesive tape of the comparative example, and the adhesive tape is used for a liquid crystal display module unit and a backlight unit in a lighting / external light type LCD. By using it for fixing, the luminance can be increased. On the other hand, the adhesive tape of the example has a transmittance of 0% and good light shielding properties, and can suppress the occurrence of poor visibility due to the backlight light leaking to the LCD surface.

It is sectional drawing of an example of the adhesive tape of this invention. It is sectional drawing of an example of the adhesive tape of this invention. It is sectional drawing of an example of the adhesive tape of this invention. It is sectional drawing of an example of the adhesive tape of this invention. It is sectional drawing of an example of the adhesive tape of this invention. It is the conceptual diagram which used the adhesive tape for fixation of a liquid crystal display module unit and a backlight unit.

Explanation of symbols

1: Base material 11: Colored layer 12: Support base material B: White layer S: Layer of color other than white and black B: Black layer 2: Adhesive layer

Claims (6)

A liquid crystal display module unit and an adhesive tape having reflectivity and light shielding properties used for fixing a backlight unit,
The adhesive tape has a base material and an adhesive layer on at least one side of the base material,
The substrate has a supporting substrate and a colored layer;
The colored layer has a white layer, a layer of a color other than white and black, and a black layer in this order,
The black layer has light shielding properties;
The white layer is reflective;
The black layer has a chromaticity L represented by L of L · a · b measured by a chromaticity meter of 25 ± 10,
The chromaticity L of the white layer is 92 ± 5;
The thickness of the colored layer is 1 to 10 μm,
The chromaticity L of the color layer other than white and black is 70 ± 10;
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive,
The acrylic pressure-sensitive adhesive is a homopolymer of an alkyl group having 1 to 18 carbon atoms (meth) acrylic acid alkyl ester, or a copolymerizable monomer of the above (meth) acrylic acid alkyl ester and another functional monomer. Using the copolymer as the base polymer,
A pressure-sensitive adhesive tape having reflectivity and light-shielding properties, wherein the copolymer monomer component constituting the base polymer contains 50% by weight or more of the alkyl (meth) acrylate.   The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 10 to 50 μm.   The pressure-sensitive adhesive tape having reflectivity and light shielding properties according to claim 1, wherein the support substrate is polyethylene terephthalate.   The thickness of the said support base material is 4-70 micrometers, The adhesive tape which has the reflective property and light-shielding property of any one of Claims 1-3 characterized by the above-mentioned.   The acrylic pressure-sensitive adhesive contains a tackifying resin and a crosslinking agent in addition to the base polymer, and has reflectivity and light shielding properties according to any one of claims 1 to 4. Adhesive tape.   A liquid crystal display device, wherein the liquid crystal display module unit and the backlight unit are fixed by the adhesive tape according to claim 1.

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