TWI538974B - Double sided pressure sensitive adhesive tape and display device having a touch panel - Google Patents

Description

Double-sided adhesive tape and display device with touch panel

The present invention relates to a double-sided adhesive tape and a display device having the touch panel. More specifically, the present invention relates to a double-sided adhesive tape and a display device having the touch panel using the double-sided adhesive tape, which is a laminated body in which a specific property is possessed An adhesive layer is provided on both sides of the core material, and the tape is suitable for use in, for example, fixing of components in a mobile product such as a mobile phone or a touch panel, and has a good fit and water resistance, and is provided on The concave-convex adaptability in the case of waterproofing or the like in the mobile information terminal having a narrow frame margin around the screen.

A mobile product such as a mobile phone or a touch panel is a device that is used without selecting an environment, and recently, there is a tendency to apply a mobile product to various occasions. In particular, the use of places with water such as coasts or bathrooms has increased, and the attendant troubles have also increased.

As a countermeasure against this, for example, Patent Document 1 discloses a double-sided adhesive tape for waterproofing, which is a double-sided adhesive tape having a foam base material and an adhesive layer, characterized in that the foam base material is 25 The % compressive strength is in the range of 40 to 160 kPa, and the tensile strength is in the range of 30 to 1500 N/cm ² . In addition, in this technique, the substrate and the adhesive are firmly bonded at the interface by foaming the substrate. . Further, since the foam base material has a separate foam structure, even when one surface of the double-sided adhesive tape is wetted by water, the water does not permeate to the other surface and exhibits water repellency. Further, the foam base material is excellent in unevenness.

However, in the case of a very narrow tape of about 1 mm, in the double-sided adhesive tape for waterproofing using a foam, there is a risk that the independent air bubble wall for controlling the penetration of water cannot be sufficiently ensured in the width direction, and sufficient space cannot be achieved. Waterproof. In addition, the size of the foam shape has a limit, and it is difficult to finely control its size.

In the mobile phone of recent years, the type of display screen is increased in terms of appearance and function, and in this case, the frame portion around the display screen is designed to be as narrow as possible. It is assumed that the double-sided adhesive tapes used are in the form of narrow frame edges having a width of 2 mm or less, but in the case of a very narrow adhesive tape width of 2 mm or less, the waterproof doubles using the foam as described above are used. In the surface adhesive tape, there is a risk that the bubble wall of the closed cells that can prevent the penetration of water is sufficiently ensured in the width direction, and there is a problem that sufficient water repellency cannot be achieved.

Prior art literature

Patent Document 1 Japanese Patent Laid-Open Publication No. 2009-108314

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a double-sided adhesive tape which is a laminated body formed by providing an adhesive layer on both faces of a core material, and is suitable for, for example, a mobile phone or a touch. In the case where the member is fixed in a moving product such as a control panel, the difference in the appropriateness of the step and the water resistance are excellent, and the unevenness is adaptable, and the concave-convex adaptability is used for waterproofing or the like in the mobile information terminal having a narrow frame edge. .

In order to achieve the above object, the inventors of the present invention conducted intensive studies, and as a result, obtained the following findings.

In other words, it has been found that a synthetic resin film having a specific property is preferably used as the core material, and an olefin polymer such as an ethylene-methacrylic acid copolymer or an ethylene-vinyl acetate copolymer is preferably used. Providing a layered body having a specific property of an adhesive layer, preferably an acrylic adhesive layer, wherein the storage elastic modulus at 0 ° C is within a specific range, according to the double-sided adhesive tape having the above structure To achieve the above objectives.

The present invention has been completed in view of the above points.

(1) A double-sided adhesive tape formed of a laminated body having a core material and an adhesive layer provided on both faces of the core material, characterized in that:

(a) The storage elastic modulus of the above laminated body at 0 ° C is in the range of 0.6 to 3.7 MPa;

(b) the tan δ (loss tangent) at 23 ° C of the above two adhesive layers are respectively 0.6 or more;

(c) The 5% tensile stress of the above core material is in the range of 3 to 100 N, and the hardness (Gorefa) is 0.2 mN or less.

(2) The double-sided adhesive tape according to the above item (1), wherein the core material is a synthetic resin film having a thickness in the range of 3 to 200 μm, and the thickness of each of the two adhesive layers is 20 to 100 μm. Within the scope.

(3) The double-sided adhesive tape according to the above item (1) or (2), wherein the adhesive constituting the two adhesive layers is an acrylic adhesive.

(4) The double-sided adhesive tape according to the above item (2) or (3), wherein the core material is an olefin polymer film.

(5) The double-sided adhesive tape according to the above item (4), wherein the olefin polymer film is an ethylene-methacrylic acid copolymer and/or an ethylene-vinyl acetate copolymer and/or polyethylene. The formed film.

(6) The double-sided adhesive tape according to any one of the above-mentioned (1), wherein the double-sided adhesive tape has a shape of a frame shape of a width of 0.1 to 2 mm.

(7) The double-sided adhesive tape according to any one of the above (1) to (6), which is used for fixing inside the mobile information terminal device.

(8) The double-sided adhesive tape according to any one of the above (1) to (7), which is for waterproofing.

(9) A display device including a touch panel, wherein the frame is fixed by the double-sided adhesive tape according to any one of the above (1) to (8).

According to the present invention, there can be provided a double-sided adhesive tape and a display device having the touch panel using the double-sided adhesive tape, wherein the double-sided adhesive tape is a laminated body in which two of the core materials are An adhesive layer is disposed on the surface, and the double-sided adhesive tape is suitable for use in, for example, fixing of components in a mobile product such as a mobile phone or a touch panel, and has a good fit and water resistance, and is used for the frame edge. The width and width of the mobile information terminal is limited to the unevenness of the weather.

First, the double-sided adhesive tape of the present invention will be described.

[double-sided adhesive tape]

The double-sided adhesive tape of the present invention is a laminate comprising a core material and an adhesive layer disposed on both faces of the core material, characterized in that: (a) the storage elastic modulus of the laminate at 0 ° C In the range of 0.6~3.7MPa;

(b) the tan δ (loss tangent) at 23 ° C of the above two adhesive layers is above 0.6;

(c) The 5% tensile stress of the above core material is in the range of 3 to 100 N, and the hardness (Gorefa) is 0.2 mN or less.

(Core)

In the double-sided adhesive tape of the present invention, the 5% tensile stress of the core material constituting the laminated body is required to be in the range of 3 to 100 N, and the soft hardness (Gore method) is 0.2 mN or less. When the tensile stress is less than 3 N, the workability is lowered. On the other hand, if it exceeds 100 N, the adhesion of the uneven surface is lowered, and the water resistance is insufficient. The tensile stress is preferably in the range of 3 to 50 N, more preferably 5 to 5 Within the range of 20N.

In addition, the hardness (Gore method) is required to be 0.2 mN or less. If the softness exceeds 0.2 mN, the surface joining force is lowered. From the viewpoint of surface bonding force, the softness is preferably 0.15 mN or less, more preferably 0.1 mN or less. The lower limit of the softness is not particularly limited, and is usually about 0.01 mN.

Further, the core material is preferably a synthetic resin film having a thickness in the range of 2 to 400 μm, more preferably a film having a thickness in the range of 10 to 200 μm, and particularly preferably a film having a thickness in the range of 50 to 150 μm.

If the thickness of the core material film is less than 2 μm, the workability of the core material itself, the shear processing suitability of the double-sided adhesive tape, the adaptability and strength of press processing cannot be sufficiently obtained. On the other hand, when it exceeds 200 μm, the unevenness and the like are lowered, and the water resistance tends to be insufficient.

Further, the above 5% tensile stress and softness (Gore method) are values measured by the following methods.

<Method for Measuring 5% Tensile Stress of Core Material>

The core material was cut to have a width of 15 mm and a length of 50 mm, and a sample for measurement was prepared. The both ends of the sample for measurement were set to 10 mm by a universal tensile tester, and the measurement was performed at a tensile speed of 200 mm/min and a width of 15 mm. The measurement portion having a length of 30 mm was a stress at 5% stretching.

<Measurement Method of Softness of Core Material (Gore Method)>

The core material was cut in a size of 38 mm in length and 25 mm in width to prepare a sample for measurement, and the softness was measured in accordance with "JIS L 1085 (1998) 6.10.3 Gore method" using a GRAY type softness tester.

The core material constituting the laminated body of the double-sided adhesive tape of the present invention satisfies the above properties and will be described below. The storage elastic modulus at 0 ° C of the laminate having the core material and the adhesive layer disposed on both faces of the core material is required to be in the range of 0.6 to 3.7 MPa, preferably in the range of 1.0 to 3.6 MPa. More preferably, it is in the range of 1.5 to 3.4 MPa. In this case, it is not particularly limited, and can be appropriately selected from conventionally known synthetic resin films.

The synthetic resin film having the above properties constituting the core material is, for example, contained in the range of 80 to 100% by mass, preferably 85 to 99% by mass, more preferably 90 to 98% by mass of the olefin monomer unit. A film formed of an olefin polymer.

Specific examples of such an olefin polymer include an ethylene-methacrylic acid copolymer, an ethylene-vinyl acetate copolymer, and polyethylene. These olefin polymers may be used singly or in combination of two or more kinds.

In order to improve the adhesion of the adhesive layer provided on the both surfaces of the film, the synthetic resin film constituting the core material may be oxidized, embossed, or the like on both sides as needed. Surface treatment or primer treatment. Examples of the oxidation method include, for example, a corona discharge treatment, a plasma discharge treatment, a chromic acid treatment (wet), a hot air treatment, an ozone ‧ an ultraviolet irradiation treatment, and the like, and the embossing treatment method includes, for example, a sand blast method or a solvent treatment. Law and so on. These surface treatment methods are appropriately selected depending on the type of the synthetic resin film, but it is preferable to use a corona discharge treatment method from the viewpoints of effects, workability, and the like.

Further, the color of the core material is not particularly limited, and it may be colorless or colored in an appropriate color.

Further, it is preferred that the core material is not a foam structure. In the double-sided adhesive tape using the core material having a foam structure, the bubble walls of the closed cells which control the penetration of water cannot be sufficiently ensured in the width direction.

(adhesive layer)

In the double-sided adhesive tape of the present invention, it is required that the two adhesive layers provided on both surfaces of the synthetic resin film constituting the core material have tan δ (loss tangent) at 23 ° C of 0.6 or more. When the tan δ is less than 0.6, the surface bonding force with the adherend is insufficient. It is preferable that tan δ is 0.7 or more, and the upper limit thereof is not particularly limited, and is usually 2.0.

Further, the thickness of the above two adhesive layers is preferably in the range of 20 to 100 μm, more preferably in the range of 40 to 70 μm. When the thickness of the adhesive layer is less than 20 μm, it is difficult to obtain sufficient surface bonding strength. On the other hand, if it exceeds 100 μm, the workability tends to be lowered.

Further, the method for measuring tan δ (loss tangent) of the adhesive layer at 23 ° C is as follows.

<Method for measuring tanδ at 23 °C>

The adhesive was laminated, and the thickness was 2 mm, and the sample for measurement was prepared by cutting with a column having a diameter of 8 mm. Next, tan δ at a temperature of 23 ° C was measured using a dynamic viscoelasticity measuring apparatus.

In the double-sided adhesive tape of the present invention, for the laminate having the core material and the adhesive layer provided on both faces of the core material, the storage elastic modulus at 0 ° C is required to be in the range of 0.6 to 3.7 MPa. If the storage modulus is less than 0.6 MPa, sufficient shearing workability cannot be obtained. On the other hand, if it exceeds 3.7 MPa, the surface joining strength is lowered. From such a viewpoint, the storage modulus is preferably in the range of 5 to 30 MPa, more preferably in the range of 1.5 to 3.4 MPa.

Further, the method for measuring the storage modulus of the laminate at 0 ° C is as follows.

<Method for Measuring Storage Elasticity at 0 ° C of Laminated Body>

A plurality of laminated bodies were stacked, and the thickness was about 2 mm, and a sample for measurement was prepared by cutting a column having a diameter of 8 mm. Next, the storage elastic modulus at a frequency of 1 Hz and a temperature of 0 ° C was measured using a dynamic viscoelasticity measuring apparatus.

In the double-sided adhesive tape of the present invention, if the corresponding properties of the two adhesive layers satisfy the above conditions, they may have the same composition and properties, or may have different compositions and properties, but from the viewpoint of productivity In terms of, it is preferred to have the same composition and properties.

The type of the adhesive constituting the two adhesive layers in the double-sided adhesive tape of the present invention satisfies the above conditions, and is not particularly limited, and various adhesives such as an acrylic adhesive and a rubber adhesive can be used. A solvent, an anthrone-based adhesive, a polyurethane adhesive, a polyester adhesive, and an ultraviolet-curable adhesive, etc., among these, from the viewpoints of weather resistance, adhesive properties, economy, and the like, preferably used Acrylic adhesive.

<Acrylic Adhesive>

In the double-sided adhesive tape of the present invention, the acrylic adhesive constituting the two adhesive layers is preferably a (meth) acrylate copolymer as a main component, and an adhesive composition containing a crosslinking agent as needed. The material is obtained by thermal crosslinking. The (meth) acrylate copolymer is not particularly limited, and any of the (meth) acrylate copolymers conventionally used as the resin component of the conventional acryl-based adhesive can be appropriately selected and used. As the (meth) acrylate copolymer, for example, a (meth) acrylate having an alkyl group of an ester moiety in a range of from 1 to 20; a monomer including a functional group having an active hydrogen; A copolymer of other monomers used as needed. Further, (meth) acrylate means methacrylate and/or acrylate.

Here, examples of the (meth) acrylate in which the number of carbon atoms of the alkyl group in the ester moiety is from 1 to 20 include methyl (meth)acrylate and ethyl (meth)acrylate. Base) propyl acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, isobutyl (meth) acrylate, amyl (meth) acrylate, (A) Ethyl hexyl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, lauric (meth) acrylate Ester, tetradecyl (meth)acrylate, cetyl (meth)acrylate, octadecyl (meth)acrylate, and the like. These may be used singly or in combination of two or more kinds.

On the other hand, examples of the monomer including a functional group having an active hydrogen include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. a (meth)acrylic acid hydroxyalkyl ester such as ester, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; (meth)acrylic acid (meth)acrylic acid such as monomethylaminoethyl ester, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate An alkylaminoalkyl ester; an ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid or citraconic acid. These may be used singly or in combination of two or more kinds.

Moreover, examples of other monomers used as needed include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and isobutylene; and vinyl chloride, vinylidene chloride, and the like. Halogenated olefins; styrene monomers such as styrene and α-methylstyrene; diene monomers such as butadiene, isoprene, and chloroprene; acrylonitrile, methacrylonitrile, etc. Nitrile monomers; acrylamides such as acrylamide, N-methyl acrylamide, N,N-dimethyl decylamine, and the like. These may be used singly or in combination of two or more kinds.

The copolymerization form of the above (meth) acrylate copolymer used as the resin component is not particularly limited, and may be any of random, block, and graft copolymers. Further, the molecular weight, the weight average molecular weight is preferably in the range of 300,000 or more, more preferably in the range of 5 to 2.5 million. When the weight average molecular weight is less than 300,000, the adhesion to the bonded body and the durability adhesiveness may be insufficient. The weight average molecular weight is preferably in the range of 70 to 1.8 million in consideration of adhesiveness, durability, and the like.

Further, the above weight average molecular weight is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

Further, in the (meth) acrylate 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. When the content is less than 0.01% by mass, the crosslinking point is too small, the crosslinking is insufficient, and the adhesive layer is likely to be agglomerated and broken. When the content is more than 10% by mass, the viscosity is increased and the coating suitability is lowered. A more preferable content of the monomer unit including a functional group having the active hydrogen is in the range of 0.05 to 6.0% by mass, particularly preferably in the range of 0.2 to 5.0% by mass.

<Crosslinking agent>

The crosslinking agent is not particularly limited, and any one of those conventionally used as a crosslinking agent in a conventional acrylic resin can be appropriately selected and used in any type. Examples of such a crosslinking agent include a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin, a dialdehyde, a methylol polymer, an aziridine compound, a metal chelate compound, and a metal alkoxide. A metal salt or the like is preferably a polyisocyanate compound.

Here, examples of the polyisocyanate compound include an aromatic polyisocyanate such as tolylene diisocyanate, diphenylmethane diisocyanate or xylylene diisocyanate, and an aliphatic polyisocyanate such as hexamethylene diisocyanate. An alicyclic polyisocyanate such as sulfone diisocyanate or hydrogenated diphenylmethane diisocyanate; and such biuret, isocyanurate, and ethylene glycol, propylene glycol, and neopentyl glycol An adduct of a reactant of a low molecular weight active hydrogen-containing compound such as trimethylolpropane or castor oil.

In the present invention, the crosslinking agent may be used singly or in combination of two or more. Further, the amount thereof is also dependent on the kind of the crosslinking agent, and is usually selected in the range of 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, per 100 parts by mass of the solid content of the (meth) acrylate copolymer. Selected within the scope.

If necessary, various additives such as a decane coupling agent, an adhesion-imparting agent, an antioxidant, an ultraviolet absorber, a light stabilizer, and the like may be contained in the above-mentioned adhesive composition insofar as the object of the present invention is not impaired. Softeners, fillers, colorants, etc.

<release sheet>

In the double-sided adhesive tape of the present invention, it is preferable to have a type in which a release sheet is stacked, from the viewpoint of convenience in transportation or use. The double-sided adhesive tape of the present invention may be in the form of being sandwiched by two release sheets, or may be overlapped with one release sheet having mold release properties on both sides, in this state being wound up. form.

The release sheet used in the double-sided adhesive tape of the present invention may be various release sheets, but as a representative embodiment, it is composed of a release sheet substrate having release properties on the surface. Examples of the substrate for a release sheet include polyethylene terephthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, and vinyl chloride copolymer. Polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene (meth)acrylic copolymer, polystyrene, polycarbonate, fluororesin, low density polyethylene, A resin film such as a linear low-density polyethylene or a triethyl fluorenyl cellulose; a high-grade paper, a coated paper, a cellophane, a laminated paper, or the like. Among these, a film of polyethylene terephthalate which is inexpensive and tough is preferable. The thickness of the substrate for release sheet is preferably in the range of 5 μm to 300 μm, more preferably in the range of 10 μm to 200 μm.

In order to impart release property to the surface of the release sheet substrate, a release agent such as an fluorenone resin, a fluorine resin, or a long-chain alkyl resin is applied to the surface thereof. Among these, an anthrone-based resin which is low in price and which has stable properties is preferable. The thickness of the release agent layer is preferably in the range of 0.05 μm to 2.0 μm, more preferably in the range of 0.1 μm to 1.5 μm.

In the manufacture of the double-sided adhesive tape of the present invention, it is preferred that the release forces of the respective release sheets have a difference. If the release force is different in advance, the risk of the adhesive layer floating from the side of the release sheet and the deformation of the adhesive layer accompanying both of the release sheets can be prevented when only the side of the light release sheet is peeled off. Danger. In addition, in the case of a double-sided adhesive tape which is wound on one side and has a release property on both sides, the release force of the inner and outer surfaces of the release sheet is different, Get the same effect.

(Manufacture of double-sided adhesive tape)

Next, a method of manufacturing the double-sided adhesive tape of the present invention will be described.

First, a solvent is added to the above-mentioned adhesive composition as needed, and the viscosity is suitable for coating to prepare a coating liquid.

Next, on the release-treated surface of the light release sheet (or the release sheet), for example, a bar coating method or a reverse roll coating method in such a manner that the film thickness after drying is in the range of 20 to 100 μm. The coating liquid is applied by a conventionally known coating method such as a doctor blade coating method, a roll coating method, a gravure coating method, a gas knife coating method, or a blade coating method, and is dried at a temperature in the range of 80 to 120 ° C. For tens of seconds to several minutes, then, the core material is bonded to make a single-sided adhesive film.

Thereafter, the coating liquid is applied to the release-treated surface of the release sheet (or the light release sheet) in the same manner as the above, in the range of 20 to 100 μm after the film thickness after drying. After drying, it is bonded to the core surface of the above-mentioned single-sided adhesive film, whereby the double-sided adhesive tape of the present invention is obtained.

Next, the use of the double-sided adhesive tape of the present invention will be described.

(Use of double-sided adhesive tape)

The double-sided adhesive tape of the present invention is a laminate in which an adhesive layer having a specific property is provided on both faces of the core film, and the storage elasticity at 0 ° C is within a specific range, and the double-sided adhesive The belt is suitable for use in, for example, fixing of a member in a mobile product such as a mobile phone or a touch panel, and has excellent fit and water resistance, and is used as a waterproof double-sided in a narrow frame-edge mobile information terminal. Adhesive tape and so on.

In the double-sided adhesive tape of the present invention, the core material adopts a synthetic resin film having specific properties, thereby having no pores and excellent water resistance, and the width is in the range of 0.1 to 2 mm, particularly in the range of 0.2 to 1 mm. For waterproofing. That is, in the action information terminal of the narrow frame type, it can be used as a double-sided adhesive tape for waterproofing.

The double-sided adhesive tape of the present invention may be in the form of a frame-like shape in which the release sheets are adhered on both faces.

Further, in the double-sided adhesive tape of the present invention, any or all of the core layer and the adhesive layer may be black. In particular, the double-sided adhesive tape is preferably black in the case where the double-sided adhesive sheet for bonding the transparent protective sheet to the outer casing is a periphery of the transparent protective plate in the display panel or the like (box) The case of the edge shape.

The black treatment of the core material or the adhesive layer can be carried out by mixing carbon black or black pigments, dyes, or the like.

The present invention also provides a display device with a touch panel, characterized in that the touch panel element and the display body are fixed by the double-sided adhesive tape of the present invention described above.

Example

Next, the present invention will be more specifically described based on the examples, but the present invention is hardly limited to these examples.

Further, each characteristic of the double-sided adhesive tape obtained in each example was determined by the following method.

(1) Storage modulus of 0°C of laminated body (double-sided adhesive tape)

The samples of the nine laminated bodies were stacked to have a thickness of about 2 mm, and were cut by a cylinder having a diameter of 8 mm to prepare a sample for measurement. Next, a storage elastic modulus at a temperature of 0 ° C was measured using a dynamic viscoelasticity measuring apparatus (manufactured by Rheometric Co., Ltd., model name "DYNAMIC ANALYZER RDA-II").

(2) tan δ (loss tangent) at 23 ° C of the adhesive layer

The adhesive was laminated, and the thickness was 2 mm, and the sample was cut according to a column having a diameter of 8 mm to prepare a sample for measurement. Next, tan δ at a frequency of 1 Hz and a temperature of 23 ° C was measured using a dynamic viscoelasticity measuring apparatus (manufactured by Rheometric Co., Ltd., model name "DYNAMIC ANALYZER RDA-II").

(3) Thickness of core material and adhesive layer

The thickness of the core material and the adhesive layer obtained in each example was measured by a constant pressure thickness gauge (manufactured by TECLOCK, product name "PG-02") in accordance with JIS K 7130.

(4) 5% tensile stress of the core material

The core material was cut at a width of 15 mm and a length of 50 mm to prepare a sample for measurement. Then, a universal tensile tester (product name "Instron 5581" manufactured by Instron Co., Ltd.) was used, and both ends of the sample for measurement were set to 10 mm, and the measurement was performed at 5% elongation at a tensile speed of 200 mm/min: a width of 15 mm. Stress at the measurement site of 30 mm in length.

(5) Softness of core material (Gorefa)

The core material was cut according to the length of 38 mm and the width of 25 mm, using [Dongyang Seiki Co., Ltd., product name "Gore-type hardness tester"], in accordance with [JIS L 1085 (1998) 6.10.3 Gorey ], the measurement was carried out.

(6) Water resistance test

The evaluation was carried out in accordance with "JIS C 0920 (2003) 14.2.7, Test of the second characteristic number 7 of the temporary diving state with a depth of 0.15 to 1 m". 1 is a plan view of a sample for measurement, FIG. 2 is a cross-sectional view taken along line A-A in the plan view, and FIG. 3 is a cross-sectional view taken along line B-B in the plan view. At the time of the test, the following test samples were prepared in which two transparent acrylate plates 1a and 1b having a longitudinal direction of 70 mm, a lateral direction of 50 mm, and a thickness of 2 mm were formed by a longitudinal dimension of 60 mm × a lateral direction of 40 mm and a width of 1 mm. The frame-like laminated member 2 is bonded to each other. The one acrylate plate 1a of the sample for measurement has a step of a black printing 3 having a cross shape of a height of 10 μm and a width of 5 mm, and the other acrylate plate is made of a smooth acrylate plate 1b having no step (see Fig. 1). 3). After the test sample was prepared, the test sample was allowed to sink to a depth of 1 m and allowed to stand for 30 minutes. Then, the presence or absence of water in the inside of the sample piece was visually confirmed, and the following criteria were used. Evaluation of water repellency.

○: There is no intrusion of water inside the sample piece (qualified)

×: Intrusion of water inside the sample piece (failed)

(7) Surface bonding force

Equipped with acrylate board (produced by Mitsubishi Rayon, product name "ACRYLITE L001", 70 × 50 × 2mm), fully coated with UV-curable ink on one side (produced by Imperial INK, the product name "POS-911 ink") ). Next, a plate made of a stainless steel plate (manufactured by PALTEK, product name "SUS304 #600", 150 × 70 × 0.5 mm, and single-sided #600) was passed through a plate having a hole having a diameter of 2 cm.

Next, the ink layer of the acrylate plate and the #600 polished surface of the stainless steel plate were bonded to a double-sided adhesive tape having a frame shape of 60 mm in the longitudinal direction, 40 mm in the lateral direction, and 2 mm in width. Then, at a speed of 10 mm/min, a universal tensile tester (manufactured by Instron Co., Ltd., product name "Instron 5581") was attached to a measuring portion of a universal tensile tester (10 mm on one side). The cube formed of a polycarbonate resin is fixed to the bottom surface of the measuring portion by an adhesive tape, and the contact portion of the measuring portion and the acrylate plate is a square of 10 mm × 10 mm), and the perforated acrylic is pressed in the surface direction. The portion where the ink application surface of the ester plate was exposed was measured, and thereby the stress (peak value of the load) when the double-sided tape was peeled off was measured.

4 is an explanatory view showing a method of measuring a surface joining force. 4(a) is a cross-sectional view, FIG. 4(b) is a perspective view, reference numeral 10 is a double-sided adhesive tape, reference numeral 11 denotes an acrylate plate having a hole, and reference numeral 12 denotes an acrylate having an ink layer 14 on the double-sided adhesive tape side. The plate, reference numeral 13, indicates the press-in direction.

(8) Strict width processing

When the NT cutter is used for cutting in a shape of a width of 1 mm and a length of 50 mm, the microgauge is used to confirm that the sample width is 1 mm ± 0.2 mm, and if it is within the range of 1 mm ± 0.2 mm, it is expressed as ○, if it is outside the range, it is represented as ×.

Preparation Example 1 Preparation of Coating Liquid 1 for Adhesive Formation

Acrylic copolymer with butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), 2-hydroxyethyl acrylate (HEA) as monomer component (BA/2EHA/HEA mass ratio = 80: 19:1, a weight average molecular weight of 800,000, and a concentration of 55 mass%) 100 parts by mass, 10 parts by mass of a binding agent (product name "PINECRYSTAL KE-359", manufactured by Arakawa Chemical Co., Ltd.), and toluene diisocyanate were added. Tri-functional group adduct (produced by Japan POLYURETHANE Co., Ltd., product name "CORONATE L", concentration: 75 mass%) 1.8 parts by mass (relative to 100 parts by mass of the solid component of the acrylate copolymer is 2.45 parts by mass), by methyl ethyl The base ketone was diluted to prepare a coating liquid 1 for forming an adhesive having a nonvolatile content of 40% by mass.

Preparation Example 2 Preparation of Coating Liquid 2 for Adhesive Formation

Acrylic copolymer with butyl acrylate (BA), acrylic acid (AA) and 2-hydroxyethyl acrylate (HEA) as monomer components (BA/AA/HEA mass ratio = 98:1.5:0.5, weight average) 30 parts by mass of the adhesive agent (product name "PINECRYSTAL KE-359", manufactured by Arakawa Chemical Industries Co., Ltd.) was added to 100 parts by mass of the molecular weight of 800,000, and the concentration was 40% by mass, and it was added to the 3-functional group of toluene diisocyanate. (manufactured by Japan POLYURETHANE Co., Ltd., product name "CORONATE L", concentration: 75 mass%) 0.5 parts by mass (relative to 100 parts by mass of the solid component of the acrylate copolymer, 0.94 parts by mass), diluted with methyl ethyl ketone, prepared The coating liquid 2 for forming an adhesive having a nonvolatile content of 30% by mass.

Preparation Example 3 Preparation of Coating Liquid 3 for Adhesive Formation

Acrylic copolymer with 2-ethylhexyl acrylate (2EHA), cyclohexyl acrylate (CHA) and 2-hydroxyethyl acrylate (HEA) as monomer components (2EHA/CHA/HEA mass ratio = 59.7 : 40:0.3, weight average molecular weight: 800,000, concentration: 40% by mass), 100 parts by mass, mixed isocyanate crosslinking agent (produced by Toyo Ink Co., product name "BHS-8515", concentration: 37.5 mass%) 3 parts by mass ( The amount of the solid component of the acrylate copolymer was 2.81 parts by mass based on 100 parts by mass of the acrylate copolymer, and the coating liquid 3 for forming an adhesive having a nonvolatile content of 30% by mass was prepared by diluting with methyl ethyl ketone.

Preparation Example 4 Modulation of Coating Liquid 4 for Adhesive Formation

Acrylic copolymer with 2-ethylhexyl acrylate (2EHA), cyclohexyl acrylate (CHA) and 2-hydroxyethyl acrylate (HEA) as monomer components (2EHA/CHA/HEA mass ratio = 59.7 : 40:0.3, weight average molecular weight: 800,000, concentration: 40% by mass) 100 parts by mass of mixed isocyanate crosslinking agent (produced by Toyo Ink Co., Ltd., product name "BHS-8515", concentration: 37.5 mass%) 0.1 parts by mass ( The 100 parts by mass of the solid content of the acrylate copolymer was 0.09 parts by mass, and diluted with methyl ethyl ketone to prepare a coating liquid 4 for forming an adhesive having a nonvolatile content of 30% by mass.

Preparation Example 5 Modulation of Coating Liquid 5 for Adhesive Formation

Acrylic copolymerization with 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA), vinyl acetate (Vac), acrylic acid (AA), 2-hydroxyethyl acrylate (HEA) as a monomer component (2EHA/BA/Vac/AA/HEA mass ratio=46.9:46.9:5:1:0.2, weight average molecular weight: 800,000, concentration: 52% by mass), 100 parts by mass, mixed to impart an adhesive (Arakawa Chemical Industry) The company produces, product name "PINECRYSTAL KE-359") 30 parts by mass, isocyanate cross-linking agent (produced by Toyo Ink Co., product name "BHS-8515", concentration 37.5 mass%) 2 parts by mass (relative to acrylate copolymer) 100 parts by mass of the solid component was 1.44 parts by mass, and the coating liquid 5 for forming an adhesive having a nonvolatile content of 40% by mass was prepared by diluting with methyl ethyl ketone.

Example 1

A film of an ethylene-methacrylic acid copolymer (manufactured by Mitsui ‧DU PONT POLYCHEMICALS, product name "N0903HC", olefin monomer unit 91% by mass) was prepared in a thickness of 100 μm, and corona treatment was performed on both surfaces to obtain a core material. membrane. Next, a coating applicator was applied to a release-treated surface of a light release sheet (manufactured by LINTEC, product name "SP-PET381031") so as to have a thickness of 50 μm after drying. The liquid 1 was dried by heating at 100 ° C for about 2 minutes to carry out thermal crosslinking. Then, the above core film was laminated on the adhesive layer to obtain a one-sided adhesive film.

Then, a blade applicator was applied to the release surface of the release sheet (manufactured by LINTEC Co., Ltd., product name "SP-PET3811") so as to have a thickness of 50 μm after drying, and the application for applying an adhesive was applied. The liquid 1 was dried by heating at 100 ° C for about 2 minutes to carry out thermal crosslinking. Then, it was bonded to the surface of the core film of the single-sided adhesive film to prepare a double-sided adhesive tape.

Example 2

In the same manner as in Example 1, except that the coating liquid 1 for forming an adhesive was used instead of the coating liquid 1 for forming an adhesive, the double-sided adhesive tape was produced.

Example 3

In the same manner as in Example 1, except that a polyethylene film (manufactured by TAMAPOLY Co., Ltd., product name "A-1", thickness: 100 μm] was used as the core material film, a double-sided adhesive tape was produced.

Example 4

In the case of Example 1, except that the core material film was formed to have a thickness of 100 μm, an ethylene-vinyl acetate copolymer (produced by Sumitomo Chemical Co., Ltd., product name "EVATATE D2045", olefin monomer unit: 95% by weight) was formed. A double-sided adhesive tape was produced in the same manner as in Example 1 except that the film was subjected to corona treatment on both surfaces.

Comparative example 1

The coating liquid for coating agent formation 1 was applied to a release sheet (manufactured by LINTEC Co., Ltd., product name "SP-PET3811"), and heated at a temperature of 100 ° C for 2 minutes to form a thickness of 50 μm on the release sheet. Adhesive layer. Further, a release sheet of a light release sheet (manufactured by LINTEC Co., Ltd., product name "SP-PET3801") was laminated on the adhesive layer to form an adhesive sheet sandwiched between two release sheets. The release-release sheet and the light-release sheet of the adhesive obtained by the release type were bonded together to form a double-sided adhesive tape. The 5% tensile stress and softness of Comparative Example 1 were measured by taking the middle layer of three as the core material.

Comparative example 2

A double-sided adhesive tape was produced in the same manner as in Example 1 except that a black polyolefin foam (manufactured by Sekisui Chemical Co., Ltd., product name "BO LA LA") having a thickness of 100 μm was used.

Comparative example 3

A double-sided fabric was produced in the same manner as in Example 1 except that a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., product name "LUMIRROR T-60") having a thickness of 100 μm was used. Adhesive tape.

Comparative example 4

In the same manner as in Example 1, except that the coating liquid for forming an adhesive 1 was used instead of the coating liquid 1 for forming an adhesive, the double-sided adhesive tape was produced.

Comparative Example 5

In the same manner as in Example 1, except that the coating liquid 1 for forming an adhesive was used instead of the coating liquid 1 for forming an adhesive, the double-sided adhesive tape was produced.

Comparative Example 6

In the same manner as in Example 1, except that the coating liquid 5 for forming an adhesive was used instead of the coating liquid 1 for forming an adhesive, the double-sided adhesive tape was produced.

Table 1 shows the evaluation results of the respective characteristics of the double-sided adhesive tape produced in accordance with the above Examples 1 to 4 and Comparative Examples 1 to 6.

Industrial use possibilities

The double-sided adhesive tape of the present invention is a laminated body formed by providing an adhesive layer on both faces of a core material, and the adhesive tape is suitable for use in a member such as a mobile phone or a touch panel, etc. The suitability and water resistance are excellent, and it is used for waterproofing or the like in a wide mobile information terminal of the frame edge.

1a. . . Transparent acrylate board

1b. . . Transparent acrylate board

2. . . Frame-like laminated member

3. . . Cross-shaped black printing

10. . . Double-sided adhesive tape

11. . . Acrylate board with holes

12. . . Acrylate board with ink layer on the side of the double-sided adhesive tape

13. . . Pressing direction

14. . . Ink layer

1 is a plan view of a sample for measurement used in a waterproof evaluation test of a double-sided adhesive tape;

Figure 2 is a cross-sectional view taken along line A-A of Figure 1;

Figure 3 is a cross-sectional view taken along line B-B of Figure 1;

4(a) and 4(b) are explanatory views showing a method of measuring the surface joining force.

Claims (10)

A double-sided adhesive tape comprising a laminated body having a core material and an adhesive layer disposed on two faces of the core material, wherein the double-sided adhesive tape has a width of 0.1 to 2 mm, The core material is not a foam structure, (a) the storage elastic modulus of the laminate at 0 ° C is in the range of 0.6 to 3.7 MPa; (b) the loss tangent tan δ of the two adhesive layers at 23 ° C is 0.6 Above; (c) The 5% tensile stress of the above core material is in the range of 3 to 20 N, and the hardness of the Gore method is 0.2 mN or less. The double-sided adhesive tape of claim 1, wherein the core material is a synthetic resin film having a thickness in the range of 3 to 200 μm, and the thickness of the two adhesive layers is in the range of 20 to 100 μm, respectively. For example, in the double-sided adhesive tape of claim 1, wherein the adhesives constituting the two adhesive layers are respectively acrylic adhesives. For example, the double-sided adhesive tape of claim 2, wherein the adhesives constituting the two adhesive layers are respectively acrylic adhesives. A double-sided adhesive tape according to any one of claims 2 to 4, wherein the core material is an olefin polymer film. A double-sided adhesive tape according to claim 5, wherein the olefin polymer film is a film formed using an ethylene-methacrylic acid copolymer and/or an ethylene-vinyl acetate copolymer and/or polyethylene. The double-sided adhesive tape according to any one of claims 1 to 4, which has a form which is punched in a frame shape. A double-sided adhesive tape according to any one of claims 1 to 4, which is used for fixing inside the mobile information terminal device. A double-sided adhesive tape according to any one of claims 1 to 4, which is used for waterproofing. A display device having a touch panel, which is fixed to the frame by a double-sided adhesive tape according to any one of claims 1 to 8.