JP5637792B2 - Double-sided adhesive tape and display device with touch panel - Google Patents

Description

  The present invention relates to a double-sided adhesive tape and a display device with a touch panel. More specifically, the present invention is a laminate in which a pressure-sensitive adhesive layer having a specific property is provided on both surfaces of a core material having a specific property, for example, for fixing a member in a mobile product such as a mobile phone or a touch panel. Adhesive suitability to steps, excellent adhesion and water resistance, and double-sided pressure-sensitive adhesive tape having irregularity followability used for waterproofing to a portable information terminal with a narrow frame width provided around the display screen, etc. And a display device with a touch panel using the double-sided adhesive tape.

In portable information terminal devices such as mobile phones, PHS, and music players, double-sided adhesive tape is used for fixing various portions such as an information display unit and a casing, a camera periphery, and a keypad. In recent years, portable information terminal devices having a wide variety of functions have been developed, and as one of them, waterproof performance is required.
As a double-sided tape having waterproof performance, for example, a double-sided pressure-sensitive adhesive tape having a foam base material and a pressure-sensitive adhesive layer is disclosed (for example, see Patent Documents 1 and 2).
The waterproof double-sided pressure-sensitive adhesive tape described in Patent Documents 1 and 2 has a polyolefin-based foam base material and an acrylic pressure-sensitive adhesive. Since the base material is foamed, the base material and the adhesive are firmly bonded at the interface. Moreover, since the above-mentioned foam base material has an independent foam structure, even if one surface of the double-sided pressure-sensitive adhesive tape gets wet with water, it does not penetrate to the other surface and exhibits waterproofness. Furthermore, the foam base material is excellent in uneven followability.
However, in the case of a very narrow tape width of about 1 mm, a waterproof double-sided tape using a foam may not be able to secure a sufficient bubble wall of closed cells for controlling water penetration in the width direction. Water resistance is not achieved. In addition, there is a limit to the size of the foam shape, and it is difficult to finely control the size.
In recent years, mobile phones with a large display screen are increasing due to demands on design and functionality, and accordingly, the frame portion around the display screen is designed to be as narrow as possible. The double-sided tape used for these is assumed to be used in the form of a narrow frame with a width of 2 mm or less, but the waterproof double-sided tape has a width of the frame for the reason derived from the foam structure as described above. There is a problem that it is difficult to make it narrow and difficult to apply to a mobile phone with a large display screen. Moreover, although it is necessary to fix a member firmly even if it becomes a narrow frame specification, since the base material is foaming, there exists a problem that the intensity | strength of a base material is low and adhesiveness does not come out easily.

JP 2009-108314 A JP 2009-242541 A

  The present invention has been made under such circumstances, and is a laminate in which an adhesive layer is provided on both surfaces of a core material, and is suitable for fixing members in mobile products such as mobile phones and touch panels. It is intended to provide a double-sided pressure-sensitive adhesive tape that has excellent conformability to a step, adhesiveness and water resistance, and has a concave-convex follow-up property used for waterproofing etc. in a portable information terminal with a narrow frame width. is there.

As a result of intensive studies to achieve the above object, the present inventors have obtained the following knowledge.
As a core material, a synthetic resin film having specific properties, preferably a film formed using an olefin polymer such as an ethylene-methacrylic acid copolymer or an ethylene-vinyl acetate copolymer, It has been found that the object can be achieved by a double-sided pressure-sensitive adhesive tape which is a laminate comprising an acrylic pressure-sensitive adhesive layer having specific properties on both sides.
The present invention has been completed based on such findings.

That is, the present invention
[1] A double-sided pressure-sensitive adhesive tape comprising a laminate having a core material not having a foam structure and pressure-sensitive adhesive layers provided on both surfaces thereof,
(A) The core material has a 5% tensile stress of 3 to 100 N and a bending resistance (Gurley method) of 0.2 mN or less,
(B) The two pressure-sensitive adhesive layers contain 1 to 60 parts by mass of a tackifying resin and 100 parts by mass of the (meth) acrylic acid ester copolymer and 100 parts by mass of the copolymer, respectively. It is formed by thermally cross-linking the pressure-sensitive adhesive composition,
It has a form that is punched into a frame shape with a width of 0.1 to 2 mm,
Double-sided adhesive tape used for fixing inside portable information terminal equipment,
[2] The double-sided pressure-sensitive adhesive tape according to the above [1], wherein the (meth) acrylic acid ester copolymer has a weight average molecular weight of 60 to 1,800,000.
[3] The double-sided pressure-sensitive adhesive tape according to the above [1] or [2], wherein the surface bonding strength measured under the following measurement conditions is 120 N or more,
(Measurement conditions) Double-sided pressure-sensitive adhesive tape processed into a frame shape with an outer dimension of 60 mm long × 40 mm wide and 2 mm wide, an ink layer in which UV curable ink is applied on one side of an acrylic plate, and a hole with a diameter of 2 cm in the center Bonded with the # 600 polished surface of a stainless steel plate that penetrates the surface, the hole is opened and the ink coating surface of the acrylic plate is exposed to the bottom surface of the measuring section of the universal tensile compression tester. A jig in which a cube made of resin is fixed is pressed in the surface direction at a speed of 10 mm / min, and the peak value of the load when the double-sided adhesive tape is peeled off is defined as the surface bonding strength.
[4] Double-sided adhesive according to any one of [1] to [3] above, wherein the core material is a film formed using an olefin polymer having 60 to 100% by mass of olefin monomer units. tape,
[5] The double-sided pressure-sensitive adhesive tape according to item [4], wherein the olefin polymer is an ethylene-methacrylic acid copolymer and / or an ethylene-vinyl acetate copolymer,
[6] The double-sided pressure-sensitive adhesive according to any one of [1] to [5], wherein the core material has a thickness of 2 to 400 μm and the two pressure-sensitive adhesive layers each have a thickness of 2 to 80 μm. tape,
[7] The double-sided pressure-sensitive adhesive tape according to any one of [1] to [6], and [8] the double-sided pressure-sensitive adhesive tape according to any one of [1] to [7], used for waterproofing. A display device with a touch panel, characterized in that the housing is fixed by
Is to provide.

  According to the present invention, it is a laminate in which an adhesive layer is provided on both surfaces of a core material, and suitable for fixing a member in, for example, a mobile product such as a mobile phone or a touch panel. To provide a double-sided pressure-sensitive adhesive tape that has excellent adhesiveness and water resistance and has a concave-convex followability used for waterproofing or the like for a portable information terminal with a narrow frame width, and a display device with a touch panel using the double-sided pressure-sensitive adhesive tape. it can.

It is a top view of the sample for a measurement used for the waterproofness evaluation test of a double-sided adhesive tape. It is the sectional view on the AA line in the said FIG. It is the BB sectional view taken on the line in the said FIG. It is explanatory drawing which shows the measuring method of surface bonding force.

First, the double-sided pressure-sensitive adhesive tape of the present invention will be described.
[Double-sided adhesive tape]
The double-sided pressure-sensitive adhesive tape of the present invention is a laminate having a core material and a pressure-sensitive adhesive layer provided on both surfaces thereof,
(A) 5% tensile stress of the core material is 3 to 100 N, and the bending resistance (Gurley method) is 0.2 mN or less,
(B) The two pressure-sensitive adhesive layers contain 1 to 60 parts by mass of a tackifying resin and 100 parts by mass of the (meth) acrylic acid ester copolymer and 100 parts by mass of the copolymer, respectively. The pressure-sensitive adhesive composition is formed by thermal crosslinking.
It is characterized by.

(Core material)
In the double-sided pressure-sensitive adhesive tape of the present invention, the core material constituting the laminate needs to have a 5% tensile stress in the range of 3 to 100 N and a bending resistance (Gurley method) of 0.2 mN or less.
By setting the 5% tensile stress of the core material to 3 to 100 N, high surface bonding force is obtained, and excellent workability and narrow frame shape workability are maintained, while having an appropriate flexibility, and therefore excellent in unevenness followability. . The tensile stress is preferably 4 to 80N, and particularly preferably 5 to 50N.
On the other hand, by setting the bending resistance (Gurley method) of the core material to 0.2 mN or less, the core material has an appropriate flexibility, and therefore has excellent unevenness followability.
Although it does not specifically limit as thickness of a core material, From a viewpoint of workability and thickness reduction, 2-400 micrometers is preferable, More preferably, it is 10-200 micrometers, and 50-150 micrometers is especially preferable. By setting it as 2 micrometers or more, the workability of the core material itself, the cutting processability of the double-sided tape, the punching processability and the strength can be secured, and the flexibility can be secured by setting it to 400 micrometers or less.

The 5% tensile stress and the bending resistance (Gurley method) are values measured by the following method.
<Method for measuring 5% tensile stress of core material>
The core material is cut into a width of 15 mm and a length of 50 mm to prepare a measurement sample. Using a tensile and compression tester, both end portions of the measurement sample are set to 10 mm, and a measurement point with a width of 15 mm and a length of 30 mm is set. The stress when stretched 5% at a pulling speed of 200 mm / min is measured.

<Measuring method of bending resistance (Gurley method) of core material>
The core material is cut into a length of 38 mm and a width of 25 mm to prepare a measurement sample. Using a Gurley type bending resistance tester, according to “JIS L 1085 (1998) 6.10.3 Gurley method”. Measure bending resistance.

  The core material constituting the laminate of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited as long as it satisfies the above-described properties, and can be appropriately selected from conventionally known synthetic resin films. .

As a synthetic resin film having the above-mentioned properties constituting the core material, for example, the olefin monomer unit is about 60 to 100% by mass, preferably 70 to 97% by mass, more preferably 80 to 94% by mass. A film formed using an olefin-based polymer containing can be suitably used.
Specific examples of such an olefin polymer include an ethylene-methacrylic acid copolymer and an ethylene-vinyl acetate copolymer. One of these olefin polymers may be used alone, or two or more thereof may be used in combination.

The synthetic resin film constituting the core material is subjected to surface treatment or primer treatment on both surfaces by an oxidation method or an unevenness method, if desired, for the purpose of improving the adhesion with the adhesive layer provided on both surfaces thereof. Can be applied. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone / ultraviolet irradiation treatment and the like, and examples of the unevenness method include a sand blast method and a solvent treatment method. Etc. These surface treatment methods are appropriately selected according to the type of the synthetic resin film, but in general, the corona discharge treatment method is preferably used from the viewpoints of effects and operability.
In addition, there is no restriction | limiting in particular about the color of the said core material, A colorless thing may be sufficient and it may be colored by the appropriate color.
Moreover, it is preferable that the said core material is not a foam structure. With a waterproof double-sided tape using a core material having a foam structure, it is not possible to sufficiently secure a closed cell foam wall for controlling the penetration of water in the width direction.

(Adhesive layer)
In the double-sided tape of the present invention, the two pressure-sensitive adhesive layers provided on both surfaces of the synthetic resin film constituting the core material described above are each a (meth) acrylic acid ester copolymer and 100 parts by mass of this copolymer. On the other hand, it is formed by thermally crosslinking an acrylic pressure-sensitive adhesive composition containing 1 to 60 parts by mass of a tackifier resin and a crosslinking agent.
In the double-sided pressure-sensitive adhesive tape of the present invention, the two pressure-sensitive adhesive layers may have the same composition and properties as long as each property satisfies the requirements described above, or have different compositions and properties. However, from the viewpoint of productivity, those having the same composition and properties are preferable.

<(Meth) acrylic acid ester copolymer>
In the acrylic pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer, the (meth) acrylic acid ester copolymer contained as a main component is not particularly limited and conventionally used as a main component of an acrylic pressure-sensitive adhesive ( Any one of the (meth) acrylic acid ester copolymers can be appropriately selected and used. As such a (meth) acrylic acid ester copolymer, for example, a (meth) acrylic acid ester having 1 to 20 carbon atoms in the alkyl group of the ester portion, a monomer having a functional group having active hydrogen, Preferred examples include copolymers with other monomers used as desired. In addition, (meth) acrylic acid ester means methacrylic acid ester and / or acrylic acid ester.

  Here, examples of the (meth) acrylic acid ester having 1 to 20 carbon atoms in the alkyl group of the ester portion include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and isopropyl (meth) acrylate. , Butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate Decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  On the other hand, examples of the monomer having a functional group having active hydrogen include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl ( Hydroxyalkyl (meth) acrylate such as (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl Monoalkylaminoalkyl (meth) acrylates such as (meth) acrylate and monoethylaminopropyl (meth) acrylate; ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, etc. But It is below. These monomers may be used independently and may be used in combination of 2 or more type.

  Examples of other monomers used as desired include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene Styrene monomers such as α-methylstyrene; diene monomers such as butadiene, isoprene and chloroprene; nitrile monomers such as acrylonitrile and methacrylonitrile; acrylamide, N-methylacrylamide, N, N- Examples include acrylamides such as dimethylacrylamide. These may be used alone or in combination of two or more.

In the acrylic pressure-sensitive adhesive composition, the (meth) acrylic acid ester copolymer used as a main component is not particularly limited as to its copolymerization form, and may be any of random, block, and graft copolymers. Good. In addition, the molecular weight is preferably 300,000 or more, more preferably 500,000 to 2,500,000 in terms of weight average molecular weight. If the weight average molecular weight is less than 300,000, the adhesion to the adherend and the durable adhesion may be insufficient. In view of adhesiveness and durable adhesiveness, the weight average molecular weight is preferably 600,000 to 1,800,000.
In addition, the said weight average molecular weight is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.
Further, in this (meth) acrylic acid ester copolymer, the content of the monomer unit having a functional group having active hydrogen is preferably in the range of 0.01 to 10% by mass. If the content is less than 0.01% by mass, the number of crosslinking points is too small, and crosslinking may be insufficient, which may cause cohesive failure of the pressure-sensitive adhesive layer. May decrease. The more preferable content of the monomer unit having a functional group having active hydrogen is 0.05 to 6.0% by mass, and the range of 0.2 to 5.0% by mass is particularly preferable.

<Tackifying resin>
In the double-sided pressure-sensitive adhesive tape of the present invention, a tackifier resin is used in order to improve adhesion to an adherend from the viewpoint that sufficient unevenness followability, adhesion, and processability can be obtained as the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. It is necessary to use. The tackifying resin is not particularly limited, and can be appropriately selected from those conventionally used as a tackifying resin in conventional pressure-sensitive adhesives. Examples of the tackifying resin include rosin resins (raw rosin, hydrogenated rosin, polymerized rosin, rosin ester), xylene resin, terpene-phenol resin, petroleum resin, coumarone indene resin, terpene resin, styrene resin, and the like. It is done.

Specific examples of commercially available products include Pine Crystal KE-359 (Arakawa Chemical Industries), Super Ester A-75 (Arakawa Chemical Industries), Super Ester A-100 (Arakawa Chemical Industries), Super Ester A. -125 [Arakawa Chemical Industries, Ltd.] and other rosin esters, Pencel D125 (Arakawa Chemical Industries, Ltd.), Pencel D160 (Arakawa Chemical Industries, Ltd.), Rikatak PCJ (Rika Finetech), etc. HP-100 [Mitsubishi Gas Chemical Co., Ltd.], Nikanol HP-150 [Mitsubishi Gas Chemical Co., Ltd.], xylene resin such as Nikanol H-80, YS Polystar T-115 [Yasuhara Chemical Co., Ltd.], Mytec G125 [Yasuhara Chemical Co., Ltd.] ] Terpene-phenol resin, FTR-6120 [manufactured by Mitsui Chemicals], FTR-6 00 there is such as petroleum resin [manufactured by Mitsui Chemicals, Inc.], and the like.
These tackifier resins may be used alone or in combination of two or more. Among them, rosin ester type is preferable from the viewpoint of tackifying effect and the like.
In the said adhesive composition, this tackifying resin needs to be 1-60 mass parts with respect to 100 mass parts of (meth) acrylic acid ester copolymers mentioned above, and is 3-50 mass parts. It is preferable that it is 5 to 40 parts by mass. By including the tackifying resin in the above range, the adhesion with the adherend becomes good.

<Crosslinking agent>
In the acrylic pressure-sensitive adhesive composition, the crosslinking agent contained is not particularly limited, and any one of those conventionally used as a crosslinking agent in an acrylic pressure-sensitive adhesive composition can be appropriately selected and used. Can do. Examples of such crosslinking agents include polyisocyanate compounds, epoxy resins, melamine resins, urea resins, dialdehydes, methylol polymers, aziridine compounds, metal chelate compounds, metal alkoxides, and metal salts. A compound is preferably used.
Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate. Polyisocyanates, etc., and biurets, isocyanurates, and adducts that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. Can be mentioned.

In this invention, this crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type. The amount used depends on the type of the crosslinking agent, but is usually 0.01 to 20 parts by mass, preferably 0.1 to 100 parts by mass of the solid content of the (meth) acrylic acid ester copolymer. It is selected in the range of -10 parts by mass.
In the acrylic pressure-sensitive adhesive composition, various additives such as a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, as long as the object of the present invention is not impaired. A colorant and the like can be contained as desired.
In the double-sided tape of the present invention, the thickness of the two pressure-sensitive adhesive layers formed using the acrylic pressure-sensitive adhesive composition is not particularly limited, but is preferably 2 to 80 μm, and preferably 5 to 60 μm. It is particularly preferred. By setting it as 2 micrometers or more, it is excellent in uneven | corrugated followable | trackability and adhesiveness with a to-be-adhered body, and is excellent in workability by setting it as 80 micrometers or less.

<Peeling sheet>
In the double-sided pressure-sensitive adhesive tape of the present invention, a laminate of release sheets is preferred for convenience during transportation and use. The double-sided pressure-sensitive adhesive tape of the present invention may be sandwiched between two release sheets, or may be laminated with a single release sheet having releasability on both sides and wound as it is.
Although various release sheets can be used as the release sheet used for the double-sided pressure-sensitive adhesive tape of the present invention, it is typically composed of a release sheet substrate having release properties on the surface. As the release sheet substrate, polyethylene terephthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, Resin films such as ethylene (meth) acrylic acid copolymer, polystyrene, polycarbonate, fluororesin, low density polyethylene, linear low density polyethylene, triacetyl cellulose, fine paper, coated paper, glassine paper, laminate paper, etc. It is done. Among these, a polyethylene terephthalate film that is inexpensive and firm is preferable. The thickness of the release sheet substrate is preferably 5 μm to 300 μm, and more preferably 10 μm to 200 μm.
In order to give the surface of the release sheet substrate a release property, it is provided by applying a release agent such as a silicone resin, a fluorine resin, or a long chain alkyl group resin to the surface. Of these, silicone resins that are inexpensive and provide stable performance are preferred. The thickness of the release agent layer is preferably 0.05 μm to 2.0 μm, and more preferably 0.1 μm to 1.5 μm.
When producing the double-sided pressure-sensitive adhesive tape of the present invention, it is preferable to make a difference in the peeling force of each release sheet. If there is a difference in the peel force, when peeling only the light release sheet side, the adhesive layer may float from the heavy release sheet side, or the adhesive layer will stretch and deform to follow both release sheets Fear can be prevented. In addition, even in the case of a double-sided pressure-sensitive adhesive tape that is laminated and wound as it is with a single release sheet that has releasability on both sides, The effect is obtained.

(Manufacture of double-sided adhesive tape)
Next, a method for producing the double-sided pressure-sensitive adhesive tape of the present invention will be described.
First, a solvent is added to the above-mentioned acrylic pressure-sensitive adhesive composition as necessary to adjust the viscosity to be suitable for coating, and a coating solution is prepared.
Next, on the release treatment surface of the light release sheet (or heavy release sheet), for example, a bar coating method or reverse so that the film thickness after drying the coating liquid is about 2 to 80 μm, preferably 5 to 60 μm. The coating is performed by a conventionally known coating method such as a roll coating method, a knife coating method, a roll knife coating method, a gravure coating method, an air doctor coating method, a doctor blade coating method, etc., and at a temperature of about 80 to 120 ° C. for several tens of seconds. After heating and drying for several minutes to thermally crosslink the pressure-sensitive adhesive composition layer, a core material is bonded thereto to produce a single-sided pressure-sensitive adhesive film.
Next, coating is performed in the same manner as described above on the release treatment surface of the heavy release sheet (or light release sheet) so that the film thickness after drying the coating solution is about 2 to 80 μm, preferably 5 to 60 μm. The double-sided pressure-sensitive adhesive tape of the present invention can be obtained by heat drying and bonding with the core surface of the single-sided pressure-sensitive adhesive film after thermal crosslinking.

  The thus obtained double-sided pressure-sensitive adhesive tape of the present invention preferably has a surface bonding strength of 120 N or more, particularly preferably 170 N or more, measured under the measurement conditions described later. By setting it to 120 N or more, excellent adhesiveness for fixing members can be obtained.

Next, the use of the double-sided pressure-sensitive adhesive tape of the present invention will be described.
[Use of double-sided adhesive tape]
The double-sided pressure-sensitive adhesive tape of the present invention is a laminate in which an acrylic pressure-sensitive adhesive layer having specific properties is provided on both surfaces of a core film having specific properties, and is a member in mobile products such as mobile phones and touch panels. Suitable for fixing, etc., excellent in bonding ability to steps, adhesion and water resistance, and used as a waterproof double-sided tape for portable information terminals with narrow frame specifications.
Since the double-sided pressure-sensitive adhesive tape of the present invention uses a synthetic resin film having specific properties as a core material, it has no pores, is excellent in water resistance, has a width of 0.1 to 2 mm, and further has a thickness of 0.1. It is used for waterproofing with a width of 2 to 1 mm. That is, it can be applied as a waterproof double-sided tape to a portable information terminal with a narrow frame specification.
As a form of the double-sided adhesive tape of this invention, it can be set as the frame shape form by which a peeling sheet is stuck on both surfaces.
Moreover, the double-sided adhesive tape of this invention can make black any layer or all the layers of a core material layer and an adhesive layer. In particular, when the double-sided pressure-sensitive adhesive tape is in a frame shape, a black one is preferable.
The blackening of the core material and the pressure-sensitive adhesive layer can be performed by mixing carbon black or a black pigment or dye.

  The present invention also provides a display device with a touch panel, in which a casing is fixed by the double-sided pressure-sensitive adhesive tape of the present invention described above.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the various characteristics of the double-sided adhesive tape obtained in each example were calculated | required according to the following method.
(1) Thickness of core material and pressure-sensitive adhesive layer The thickness of the core material and pressure-sensitive adhesive layer obtained in each example was determined according to JIS K 7130 by using a constant pressure thickness measuring instrument [manufactured by Teclock Corporation, product name “PG -02 "].
(2) 5% tensile stress of core material The core material obtained in each example was cut into a width of 15 mm and a length of 50 mm to prepare a measurement sample. Then, using a tensile tester [manufactured by Shimadzu Corporation, model number “AG-IS”], set both ends 10 mm of the sample for measurement, and measure the measurement location with a width of 15 mm and a length of 30 mm at a temperature of 23 ° C. The stress when stretched 5% at a pulling speed of 200 mm / min was measured.
(3) Bending softness of core material (Gurley method)
The core material is cut into a length of 38 mm and a width of 25 mm to prepare a measurement sample, and the product name is “JIS L 1085 (1998)” manufactured by Toyo Seiki Co., Ltd., product name “Gurley type flexibility tester”. It was measured according to “6.13 Gurley method”.
(4) Waterproof test The evaluation was performed according to “Test for the second characteristic number 7 in a temporary diving state of JIS C 0920 (2003) 14.2.7, 0.15 to 1 m in depth”. FIG. 1 is a plan view of a measurement sample, FIG. 2 is a cross-sectional view taken along line AA in the plan view, and FIG. 3 is a cross-sectional view taken along line BB in the plan view. In the test, a sample for measurement in which two transparent acrylic plates 1a and 1b having a length of 70 mm, a width of 50 mm, and a thickness of 2 mm are bonded together with a frame-shaped laminated member 2 having an outer dimension of 60 mm × width 40 mm and a width of 1 mm. Was made. One acrylic plate 1a of the measurement sample has a step having a cross-shaped black print 3 having a height of 10 μm and a width of 5 mm, and the other used a smooth acrylic plate 1b having no step (FIGS. 1 to 1). (See FIG. 3). After preparing the measurement sample, 24 hours later, submerge the measurement sample to a depth of 1 m and let it stand for 30 minutes, and then visually check whether water has entered the specimen and waterproof it according to the following criteria. Sex was evaluated.
○: No penetration of water into the test piece (pass).
X: There is water intrusion inside the specimen (failed).
(5) Surface bonding force An acrylic plate [Mitsubishi Rayon Co., Ltd., product name “Acrylite L001”, 70 × 50 × 2 mm ”] was prepared, and UV curable ink [Empire Ink Co., Ltd., product name“ POS- 911 ink "] was applied to the entire surface. Next, a stainless steel plate [manufactured by Partec Co., Ltd., product name “SUS304 # 600”, 150 × 70 × 0.5 mm, single-sided # 600 polishing] having a hole with a diameter of 2 cm in the center thereof was prepared.
Next, the ink layer of the acrylic plate and the # 600 polished surface of the stainless steel plate were bonded together with a double-sided tape processed into a frame shape having an outer dimension of 60 mm long × 40 mm wide and 2 mm wide. Then, at a speed of 10 mm / min, using a universal tensile / compression tester [Instron, product name “Instron 5581 type”], the portion where the ink coating surface of the acrylic plate is exposed is shown Jig fixed to the measurement part of the tensile and compression tester (cube made of polycarbonate resin with a side of 10 mm fixed to the bottom of the measurement part with adhesive tape, the contact part between the measurement part and the acrylic plate is a 10 mm × 10 mm square) The stress (load peak value) when the double-sided tape was peeled off was measured by pressing in the surface direction.
FIG. 4 is an explanatory diagram showing a method for measuring the surface bonding force. 4, (a) is a cross-sectional view, (b) is a perspective view, 10 is a double-sided adhesive tape, 11 is a stainless steel plate having holes, 12 is an acrylic plate having an ink layer 14 on the double-sided adhesive tape side, 13 Is the pushing direction.
(6) Narrow width workability When cutting into a shape of 1 mm wide and 50 mm long using an NT cutter, using a micro gauge, confirm that the sample width is 1 mm ± 0.2 mm, 1 mm If it was within the range of ± 0.2 mm, it was marked as ◯, and if it was outside the range, it was marked as x.

Preparation Example 1 Preparation of Adhesive Forming Coating Liquid 1 Acrylate ester copolymer (2EHA / BA / AAc) containing butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), and acrylic acid (AAc) as monomer components (Mass ratio = 80/19/1, weight average molecular weight 600,000, solid content 55 mass%) 100 mass parts, tackifier resin [Arakawa Chemical Industries, product name “Pine Crystal KE-359”] 5 mass parts, Isocyanate-based crosslinking agent [manufactured by Toyo Ink Co., Ltd., product name “BHS-8515”, solid content: 37.5% by mass] 3.6 parts by mass (2.45 parts per 100 parts by mass of the acrylic ester copolymer solids) Parts by mass) and mixed to prepare a coating solution 1 for forming an adhesive.

Preparation Example 2 Preparation of Adhesive Forming Coating Liquid 2 Acrylate ester copolymer (BA / AAc / HEA mass) containing butyl acrylate (BA), acrylic acid (AAc), and 2-hydroxyethyl acrylate (HEA) as monomer components Ratio = 98 / 1.5 / 0.5, weight average molecular weight 600,000, solid content 40% by mass) and 100 parts by mass of tackifier resin [Arakawa Chemical Industries, product name “Pine Crystal KE-359”] 20 Parts by mass, isocyanate-based crosslinking agent [manufactured by Toyo Ink Co., Ltd., product name “BHS-8515”, solid content 37.5% by mass] 1 part by mass (based on 100 parts by mass of the solid content of the acrylate copolymer) 94 parts by mass) were mixed to prepare an adhesive coating solution 2.

Preparation Example 3 Preparation of Adhesive-Forming Coating Liquid 3 Acrylate ester copolymer [BA / MA / AAc mass ratio = 77] containing butyl acrylate (BA), methyl acrylate (MA), and acrylic acid (AAc) as monomer components / 20/3, copolymer having a weight average molecular weight of 800,000, solid content of 28% by mass) and 100 parts by mass of an isocyanate-based crosslinking agent [product name “BHS-8515” manufactured by Toyo Ink Co., Ltd., solid content of 37.5 mass %] 1.8 parts by mass (2.41 parts by mass with respect to 100 parts by mass of the solid content of the acrylate copolymer) and an aluminum chelate-based crosslinking agent [M-5A, solid content 4.95, manufactured by Soken Chemical Co., Ltd. % By mass] (0.32 parts by mass with respect to 100 parts by mass of the solid content of the acrylate copolymer) was mixed to prepare a coating solution 3 for forming an adhesive.

Preparation Example 4 Preparation of Adhesive Forming Coating Liquid 4 Acrylate ester copolymer (BA / MA / 4HBA mass) containing butyl acrylate (BA), methyl acrylate (MA), 4-hydroxybutyl acrylate (4HBA) as monomer components Ratio = 79/20/1, copolymer having a weight average molecular weight of 900,000, solid content of 30% by mass) and 100 parts by mass of an isocyanate-based crosslinking agent [manufactured by Soken Chemical Co., Ltd., product name “TD-75”, solid content of 75 Mass%] 0.05 parts by mass (0.13 parts by mass with respect to 100 parts by mass of the solid content of the acrylate copolymer) was mixed to prepare a coating solution 4 for forming an adhesive.

Example 1
An ethylene-methacrylic acid copolymer [Mitsui / DuPont Polychemical Co., Ltd., product name “N0903HC”, olefinic monomer unit 91 mass%] is formed to a thickness of 100 μm and subjected to corona treatment on both sides to form a core material A film was obtained. Next, the pressure-sensitive adhesive forming coating solution 1 is applied to the release-treated surface of a light release sheet [manufactured by Lintec Corporation, trade name “SP-PET381031”] using a knife coater so that the thickness after drying becomes 50 μm. And then thermally crosslinked at 100 ° C. for about 2 minutes. Thereafter, the above core material film was laminated on the pressure-sensitive adhesive layer to obtain a single-sided pressure-sensitive adhesive film.
Next, the pressure-sensitive adhesive-forming coating solution 1 is applied to the release-treated surface of the heavy release sheet [manufactured by Lintec Corporation, trade name “SP-PET3811”] using a knife coater so that the thickness after drying becomes 50 μm. After applying and drying by heating at 100 ° C. for about 2 minutes and thermally cross-linking, the double-sided pressure-sensitive adhesive tape was prepared by bonding to the core material film surface of the single-sided pressure-sensitive adhesive film.

Example 2
A double-sided pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that the adhesive-forming coating solution 2 was used in place of the adhesive-forming coating solution 1 in Example 1.

Example 3
In Example 1, the same procedure as in Example 1 was performed except that a corona treatment was applied to both sides of a polyethylene film [manufactured by Tamapoly, product name “A-1”, thickness of 100 μm] as the core film. A double-sided adhesive tape was prepared.

Example 4
In Example 1, an ethylene-vinyl acetate copolymer [manufactured by Sumitomo Chemical Co., Ltd., product name “Evertate D2045, olefin monomer unit 95 mass%] as a core film was formed to a thickness of 100 μm, and both sides were formed. A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that a corona-treated one was used.

Comparative Example 1
A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that the adhesive-forming coating solution 3 was used instead of the adhesive-forming coating solution 1 in Example 1.

Comparative Example 2
A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that the adhesive-forming coating solution 4 was used instead of the adhesive-forming coating solution 1 in Example 1.

Comparative Example 3
In Example 1, a double-sided pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that a black polyolefin-based foam having a thickness of 100 μm [manufactured by Sekisui Chemical Co., Ltd., product name “Borara”] was used as the core material film. Was made.

Comparative Example 4
A double-sided pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that a polyethylene terephthalate (PET) film having a thickness of 100 μm [product name “Lumirror T-60” manufactured by Toray Industries, Inc.] was used as the core material. .

Comparative Example 5
The pressure-sensitive adhesive forming coating solution 1 was dried on a release surface of a heavy release sheet [manufactured by Lintec Corporation, trade name “SP-PET3811”] with a knife coater, and the thickness after drying with a knife coater was 50 μm. After applying and drying by heating at 120 ° C. for about 2 minutes and thermally cross-linking, a light release sheet [manufactured by Lintec Co., Ltd., trade name “SP-PET 381031”] was bonded. Next, three sheets of the obtained pressure-sensitive adhesive were bonded together to produce a double-sided pressure-sensitive adhesive tape. The 5% tensile stress and the bending resistance of Comparative Example 5 were measured by regarding the middle layer of the three sheets as a core material.
Table 1 shows the evaluation results of various characteristics of the double-sided pressure-sensitive adhesive tapes produced in Examples 1 to 4 and Comparative Examples 1 to 5.

  The double-sided pressure-sensitive adhesive tape of the present invention is a laminate in which pressure-sensitive adhesive layers are provided on both surfaces of a core material, and is suitable for fixing a member in a mobile product such as a mobile phone or a touch panel. It is excellent in suitability, adhesiveness and water resistance, and is used for waterproofing etc. in a portable information terminal having a narrow frame width.

DESCRIPTION OF SYMBOLS 1a Transparent acrylic board 1b Transparent acrylic board 2 Frame-shaped laminated member 3 Cross-shaped black printing 10 Double-sided adhesive tape 11 Stainless steel board which has a hole 12 Acrylic board which double-sided adhesive tape side has an ink layer 13 Pushing direction 14 Ink layer

Claims (8)

A double-sided pressure-sensitive adhesive tape comprising a laminate having a core material that is not a foam structure and an adhesive layer provided on both surfaces thereof,
(A) The core material has a 5% tensile stress of 3 to 100 N and a bending resistance (Gurley method) of 0.2 mN or less,
(B) Each of the two pressure-sensitive adhesive layers contains 1 to 60 parts by mass of a tackifying resin and a crosslinking agent with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer and the copolymer, respectively. It is formed by thermally cross-linking the pressure-sensitive adhesive composition,
It has a form that is punched into a frame shape with a width of 0.1 to 2 mm,
Double-sided adhesive tape used for fixing inside portable information terminal equipment.   The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the (meth) acrylic acid ester copolymer has a weight average molecular weight of 60 to 1,800,000. The double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein the surface bonding strength measured under the following measurement conditions is 120 N or more.
(Measurement conditions) Double-sided pressure-sensitive adhesive tape processed into a frame shape with an outer dimension of 60 mm long × 40 mm wide and 2 mm wide, an ink layer in which UV curable ink is applied on one side of an acrylic plate, and a hole with a diameter of 2 cm in the center Bonded with the # 600 polished surface of a stainless steel plate that penetrates the surface, the hole is opened and the ink coating surface of the acrylic plate is exposed to the bottom surface of the measuring section of the universal tensile compression tester. A jig in which a cube made of resin is fixed is pressed in the surface direction at a speed of 10 mm / min, and the peak value of the load when the double-sided adhesive tape is peeled off is defined as the surface bonding strength.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein the core material is a film formed using an olefin polymer having 60 to 100% by mass of an olefin monomer unit.   The double-sided pressure-sensitive adhesive tape according to claim 4, wherein the olefin polymer is an ethylene-methacrylic acid copolymer and / or an ethylene-vinyl acetate copolymer.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein the thickness of the core material is 2 to 400 µm, and the thicknesses of the two pressure-sensitive adhesive layers are 2 to 80 µm, respectively.   The double-sided pressure-sensitive adhesive tape according to claim 1, which is used for waterproofing.   A display device with a touch panel, wherein the casing is fixed by the double-sided pressure-sensitive adhesive tape according to claim 1.

Images