JP2007153954A - Adhesive tape for shading - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive tape for shading, capable of exerting functions such as adhesion property and punchability and showing no exudation of a glue. <P>SOLUTION: The adhesive tape for shading comprises a substrate, a shading layer formed on at least one surface of the substrate and an adhesive layer. The adhesive layer is formed from an adhesive containing a synthetic rubber component and a tackifier resin, wherein the synthetic rubber component is obtained by mixing a styrene-isoprene copolymer (A) having an SI diblock content of 25-35%, an average molecular weight of 150,000-250,000 and a styrene content of 18-21% and a styrene-isoprene copolymer (B) having an SI diblock content of 50-60%, an average molecular weight of 120,000-220,000 and a styrene content of 14-17% in a weight ratio (A):(B) of from 40:60 to 60:40. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-blocking pressure-sensitive adhesive tape that can be effectively used for, for example, adhering and fixing a liquid crystal display panel and a backlight unit.

  An LCD (Liquid Crystal Display) module is used as a display device for electronic devices such as electronic notebooks and mobile phones, which have been increasingly miniaturized in recent years. Among LCD modules, a sidelight type backlight type LCD module generally includes a backlight unit in which a reflective sheet, a light guide plate, a diffusion sheet, a prism sheet, and an LCD panel are sequentially laminated. A lamp reflector is provided, and a light source such as an LED (Light Emitting Diode) is disposed.

  A double-sided adhesive tape formed in a frame shape is usually sandwiched between the LCD panel and the backlight unit, fixing each member and preventing intrusion of dust, and its cushioning properties Protects each member from impact.

  In addition, LCD modules are becoming larger and smaller with lighter and smaller sizes and the amount of information is increasing. As the position of the light source and the LCD panel gets closer, light from the light source leaks through the adhesive tape. There is a risk that the appearance of the display surface of the LCD panel deteriorates.

  Therefore, the adhesive tape sandwiched between the LCD panel and the backlight unit is required to have a high light-shielding property, improving the appearance of the display surface of the LCD panel, and a driver for driving the LCD panel. Therefore, it was required to block the entrance of light and prevent malfunction.

  As such an adhesive tape, one in which a pressure sensitive adhesive containing a black colorant is coated on one side or both sides of a base film having a light transmittance of 1% or less has already been proposed (Patent Document 1). reference).

  By the way, in recent years, in order to reduce the thickness, size, and weight of mobile devices, the functions of reducing the thickness and weight of these double-sided tape members have been demanded. Further, along with the narrowing and miniaturization of the liquid crystal display module unit and the backlight unit, more fixed adhesive force and punching workability than before are required.

  In addition, after a liquid crystal module and a backlight module are combined with a tape, when a defect is found by inspection or the like, an operation for disassembling a liquid crystal module that is more expensive than the backlight module will be performed. However, if glue remains on the glass surface on the side of the liquid crystal module at that time, it becomes difficult to reuse. Further, when a sheet is punched by using a sheet having a low cohesive force and then peeled off, there may be a problem in quality due to occurrence of a lump of glue or stringing.

JP 2002-215053 A

  In view of the above circumstances, an object of the present invention is to provide a light-shielding pressure-sensitive adhesive tape that can exhibit the functions of adhesiveness and punching workability, and that does not cause paste stains.

  In order to achieve the above object, a light-shielding pressure-sensitive adhesive tape according to the present invention comprises a base material, a light-shielding layer formed on at least one surface of the base material, and a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer has an SI diblock amount of 25 to 35%, an average molecular weight of 1 to 250,000 and a styrene amount of 18 to 21%, and an SI diblock amount of SI copolymer. A styrene-isoprene copolymer (B) having a weight ratio of 50 to 60%, an average molecular weight of 1 to 220,000, and a styrene amount of 14 to 17% is styrene-isoprene copolymer (A): styrene-isoprene copolymer. It is characterized by being formed of a pressure-sensitive adhesive containing a synthetic rubber component mixed in a ratio of coalescence (B) = 40: 60 to 60:40 and a tackifying resin.

  In the present invention, the synthetic rubber component comprises a styrene-isoprene copolymer (A) and a styrene-isoprene copolymer (B) in a weight ratio of styrene-isoprene copolymer (A): styrene-isoprene copolymer. It is necessary to mix | blend in the ratio of unification (B) = 40: 60-60: 40.

  The styrene-isoprene copolymer (A) is not particularly limited, and commercially available products such as “trade name: Nipol” manufactured by Nippon Zeon Co., Ltd. can be used. Further, the styrene-isoprene copolymer (B) is not particularly limited, and for example, commercially available products such as “trade name: Asahi Tech” manufactured by Asahi Chemical Synthesis Co., Ltd. can be used.

  Although it does not specifically limit as tackifying resin, For example, "brand name: quinton" by Nippon Zeon, "brand name: Superester" by Arakawa Chemical Co., etc. are mentioned, Among them, Softening point 85-100 degreeC, Bromine An aliphatic hydrocarbon resin having a value of 30 to 40 g / 100 g and a number average molecular weight of 1000 to 1200 is preferred.

  The blending ratio of the tackifying resin is appropriately determined depending on the type of the resin. For example, the tackifying resin is not particularly limited. For example, the softening point is 85 to 100 ° C., the bromine number is 30 to 40 g / 100 g, When an aliphatic hydrocarbon resin having a number average molecular weight of 1000 to 1200 is used, it is preferably about 50 to 150 parts by weight with respect to 100 parts by weight of the synthetic rubber component.

Moreover, you may make it add a solvent, an anti-aging agent, etc. to the adhesive used by this invention as needed other than the said synthetic rubber component and tackifying resin.
Although it does not specifically limit as a solvent, For example, acetone, toluene, ethyl acetate, etc. are mentioned.
The blending ratio of the solvent is not particularly limited, but is preferably 150 to 200 parts by weight with respect to 100 parts by weight of the synthetic rubber component. When the blending ratio of the solvent is out of the above range, there may be a problem in appearance.
Although it does not specifically limit as an anti-aging agent, A bisphenol-type thing is preferable.

  Furthermore, the light-shielding pressure-sensitive adhesive tape of the present invention preferably has a thin coating layer between the light-shielding layer and the pressure-sensitive adhesive layer. That is, the thin coat layer can have an anchoring effect that improves the adhesive force of the pressure-sensitive adhesive layer to the printed layer, and this anchor effect causes adhesive residue on the glass surface due to interface peeling between the light-shielding layer and the pressure-sensitive adhesive layer. It is possible to expect the effect of reducing the above.

The thin coating layer is obtained by coating the coating agent so as to cover the surface of the light shielding layer before the adhesive is applied, and the thickness is preferably about 0.1 μm to 1.5 μm.
The coating agent is not particularly limited as long as it can prevent blocking of the light shielding layer, and examples thereof include primary amine-grafted acrylic polymers, and commercial products such as trade names such as Poliment NK-350 and Poliment NK-380 manufactured by Nippon Shokubai Co., Ltd. Can be used.

Although it does not specifically limit as a base material used in this invention, For example, the sheet-like molded object which consists of paper, a nonwoven fabric, polyester, polyolefin, a polyurethane, a polychloroprene, a vinyl chloride resin, an acrylic resin etc. is mentioned.
The thickness of a base material is suitably determined according to the use for which an adhesive tape is used.

In the present invention, the light shielding layer may be provided only on one side of the substrate, or may be provided on both sides.
Further, a light-shielding layer made of a black ink composition may be provided on one side of the substrate, and a reflective layer such as a white print layer or a metal foil layer made of a white ink composition may be provided on the other side.

  Although it does not specifically limit as black ink used for the light shielding layer of this invention, For example, an acrylic type printing ink is mentioned, A thing with a carbon content of less than 12 weight% is preferable. Specifically, commercially available black inks (“trade name: univia A-300” manufactured by Dainippon Ink & Chemicals, Inc., “trade name: NB300-701 black” manufactured by Dainichi Seika Kogyo Co., Ltd.) can be used.

  The black ink composition of the present invention also contains an isocyanate curing agent, but the isocyanate curing agent is not particularly limited. For example, tolylene diisocyanate, naphthylene-1,5-diisocyanate, diphenylmethane diisocyanate, hexa Examples include methylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, and trimethylolpropane modified tolylene diisocyanate.

  The printing method for forming the light shielding layer is not particularly limited, and examples thereof include known and commonly used printing methods such as letterpress printing, dry offset printing, and gravure printing. A layer may be used.

  In the case of the pressure-sensitive adhesive tape of the present invention, a release sheet may be laminated on the pressure-sensitive adhesive layer.

  Since it is configured as described above according to the present invention, it can exhibit the functions of adhesiveness and punching workability, and there is no paste bleeding.

  In addition, if a thin coat layer is provided between the light shielding layer and the pressure-sensitive adhesive layer, an anchor effect that improves the adhesive force of the pressure-sensitive adhesive layer to the printed layer can be provided. The effect of reducing adhesive residue on the glass surface due to interfacial peeling between the light shielding layer and the pressure-sensitive adhesive layer can be expected.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
FIG. 1 shows one embodiment of a light-shielding pressure-sensitive adhesive tape according to the present invention.

As shown in FIG. 1, this light-shielding pressure-sensitive adhesive tape (hereinafter referred to as “adhesive tape” only) 1 has a pressure-sensitive adhesive layer 3 laminated on both surfaces of a tape body 2.
The tape body 2 includes a base material 4, a light shielding layer 5, and a thin coat layer 6.
The light shielding layer 5 is formed on both surfaces of the base material layer 4 by printing a black ink composition containing an acrylic ink and an isocyanate curing agent, and the total thickness is 7 μm or more.

The thin coat layer 6 is formed by applying and drying a coating agent such as a primary amine graft acrylic polymer on the surface of the light shielding layer 5.
The pressure-sensitive adhesive layer 3 has a styrene-isoprene copolymer (A) having an SI diblock amount of 25 to 35%, an average molecular weight of 1 to 250,000 and a styrene amount of 18 to 21%, and an SI diblock amount of 50 to 60. %, Styrene-isoprene copolymer (B) having an average molecular weight of 12-220,000 and a styrene amount of 14-17%, by weight ratio, styrene-isoprene copolymer (A): styrene-isoprene copolymer (B ) = A synthetic rubber component mixed at a ratio of 40:60 to 60:40, an aliphatic system having a softening point of 85 to 100 ° C. as a tackifier resin, a bromine number of 30 to 40 g / 100 g, and a number average molecular weight of 1000 to 1200 It forms on both surfaces of the tape main body 2 obtained by the adhesive containing a hydrocarbon resin.

  Specific examples of the present invention will be described in detail below in comparison with comparative examples.

Example 1
[Adhesive]
50 parts by weight of a styrene-isoprene copolymer (A) (manufactured by Nippon Zeon "trade name: Nipol"; SI diblock amount 30%, average molecular weight 200,000, styrene amount 19%) and styrene-isoprene copolymer ( B) (Asahi Chemical Synthesis Co., Ltd. “trade name: Asahi Tech”; SI diblock amount 50%, average molecular weight 160,000, styrene amount 15%) 50 parts by weight and tackifying resin (manufactured by Zeon Corporation “trade name” : Quinton "; softening point 98 ° C., bromine number 35 g / 100 g, number average molecular weight 1100) 90 parts by weight, bisphenol anti-aging agent 1 part by weight, toluene 180 parts by weight.

[Black ink composition]
An isocyanate-based curing agent was blended at a ratio of 7% by weight with black ink (Dainippon Ink & Chemicals, “trade name: Unibia A-3008”).

  Using the black ink composition, a 12 μm-thick polyethylene terephthalate tape-shaped substrate was formed with a first light-shielding layer having a thickness of 2 μm on one surface and a second light-shielding layer having a thickness of 5 μm on the other surface. The curing curing was performed for 8 to 24 hours for each layer.

Next, a coating agent (“trade name: Poliment NK-350” manufactured by Nippon Shokubai Co., Ltd.) was applied to the surfaces of both light shielding layers to form a thin coating layer having a thickness of 0.1 μm to obtain a tape body.
And the said adhesive was apply | coated to the surface of both thin coat layers, ie, both surfaces of a tape main body, the 25-micrometer-thick adhesive layer was formed, and the adhesive tape of thickness 88 micrometers was obtained.

(Example 2)
Except that the styrene-isoprene copolymer (A) was 60 parts by weight and the styrene-isoprene copolymer (B) was 40 parts by weight, an adhesive having the same composition as in Example 1 was used. An adhesive tape was obtained in the same manner.

(Example 3)
Except that the styrene-isoprene copolymer (A) was 40 parts by weight and the styrene-isoprene copolymer (B) was 60 parts by weight, an adhesive having the same composition as that of Example 1 was used. An adhesive tape was obtained in the same manner.

Example 4
An adhesive tape was obtained in the same manner as in Example 1 except that the thin coat layer was not provided.

(Comparative Example 1)
Except that 70 parts by weight of the styrene-isoprene copolymer (A) and 30 parts by weight of the styrene-isoprene copolymer (B) were used, an adhesive having the same composition as in Example 1 was used. An adhesive tape was obtained in the same manner.

(Comparative Example 2)
Except that the styrene-isoprene copolymer (A) was 30 parts by weight and the styrene-isoprene copolymer (B) was 70 parts by weight, an adhesive having the same composition as that of Example 1 was used. An adhesive tape was obtained in the same manner.

(Comparative Example 3)
As an adhesive, 100 parts by weight of an acrylic resin (“trade name: DB153A” manufactured by Soken Chemical Co., Ltd.), 10 parts by weight of a phenolic resin (“trade name: YS Polystar” manufactured by Yasui Chemicals), and a curing agent (Nippon Polyurethane) “Trade name: Coronate L55” manufactured by the company) An adhesive tape was obtained in the same manner as in Example 1 except that 2.2 parts by weight and 77.8 parts by weight of ethyl acetate as a solvent were used.

(Comparative Example 4)
As an adhesive, 100 parts by weight of an acrylic resin (“trade name: DB153A” manufactured by Soken Chemical Co., Ltd.), 10 parts by weight of a rosin resin (“trade name: Pencel D125” manufactured by Arakawa Chemical Co., Ltd.), and a curing agent (Nippon Polyurethane) “Trade name: Coronate L55” manufactured by the company) An adhesive tape was obtained in the same manner as in Example 1 except that 2.2 parts by weight and 77.8 parts by weight of ethyl acetate as a solvent were used.

(Comparative Example 5)
As an adhesive, 100 parts by weight of an acrylic resin (“trade name: DB153A” manufactured by Soken Chemical Co., Ltd.), 10 parts by weight of a rosin resin (“trade name: Harrier Star” manufactured by Harima Kasei Co., Ltd.), and a curing agent (Nippon Polyurethane) “Trade name: Coronate L55” manufactured by the company) An adhesive tape was obtained in the same manner as in Example 1 except that 2.2 parts by weight and 77.8 parts by weight of ethyl acetate as a solvent were used.

(Comparative Example 6)
As an adhesive, 100 parts by weight of an acrylic resin (trade name: DB153A, manufactured by Soken Chemical Co., Ltd.), 10 parts by weight of a xylene-based resin (trade name: Nikatrulen, manufactured by Mitsubishi Chemical Corporation), and a curing agent (manufactured by Nippon Polyurethane Co., Ltd.) "Product name: Coronate L55") An adhesive tape was obtained in the same manner as in Example 1 except that 2.2 parts by weight and 77.8 parts by weight of ethyl acetate as a solvent were used.

The pressure-sensitive adhesive tapes obtained in Example 1 and Comparative Examples 1 to 6 were subjected to a 180 ° peel test cohesive strength test and a paste smearing test and examined for the presence of stringing. The results are shown in Table 1. .

The 180 ° peel test was performed in accordance with JISZ0237.
In the cohesive strength test, the amount of displacement of the pressure-sensitive adhesive sheet when a load of 200 g was applied was measured.
In the paste smearing test, a load of 500 g was applied on the pressure-sensitive adhesive sheet, the paste smearing was visually observed.
The stringing was visually evaluated.

  For the adhesive tape of Example 1 and Comparative Example 3, after fixing the LCD module and the backlight unit, the backlight unit was separated from the LCD module by applying an external load, and the presence or absence of adhesive residue was observed. The results are shown in Table 2. In Table 2, “◯” indicates that there is no glue residue, and “×” indicates that there is glue residue.

  As shown in Table 3, no adhesive residue was generated on the backlight unit side and the LCD panel side of the adhesive tape of Example 1, and only the LCD panel could be separated from the backlight unit. In the case of Example 1, since the thin coating layer is provided, it is considered that the glue can be prevented from sticking to the glass due to an anchor (adhesive force) effect with the adhesive layer of the thin coating layer. Therefore, if a thin coating layer is provided as in Example 1, after the LCD module and the backlight unit are combined with the adhesive tape, a defect is found by inspection or the like, and the adhesive is peeled off when the backlight unit is peeled and decomposed. It is considered that it is easy to reuse the expensive LCD module without remaining.

  The light-blocking pressure-sensitive adhesive tape according to the present invention is used for adhesively fixing an LCD panel and a backlight unit, for example, in an electronic device equipped with a liquid crystal display screen such as a mobile phone, a portable game machine, and a car navigation system. It can be used effectively.

It is sectional drawing showing one embodiment of the adhesive tape for light shielding concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light shielding adhesive tape 2 Tape main body 3 Adhesive layer 4 Base material 5 Light shielding layer 6 Thin coat layer

Claims (3)

A light-shielding pressure-sensitive adhesive tape comprising a base material, a light-shielding layer formed on at least one surface of the base material, and an adhesive layer,
The pressure-sensitive adhesive layer has a styrene-isoprene copolymer (A) having an SI diblock amount of 25 to 35%, an average molecular weight of 1 to 250,000, and a styrene amount of 18 to 21%;
A styrene-isoprene copolymer (B) having an SI diblock amount of 50 to 60%, an average molecular weight of 1 to 220,000 and a styrene amount of 14 to 17%, and a styrene-isoprene copolymer (A) by weight ratio: Styrene-isoprene copolymer (B) = A light-blocking pressure-sensitive adhesive tape formed of a pressure-sensitive adhesive containing a synthetic rubber component mixed in a ratio of 40:60 to 60:40 and a tackifying resin. . The light-blocking pressure-sensitive adhesive tape according to claim 1, wherein the tackifying resin is an aliphatic hydrocarbon resin having a softening point of 85 to 100 ° C, a bromine number of 30 to 40 g / 100 g, and a number average molecular weight of 1000 to 1200.   The light-shielding pressure-sensitive adhesive tape according to claim 1 or 2, further comprising a thin coat layer between the light-shielding layer and the pressure-sensitive adhesive layer.

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