TWI793330B - double sided adhesive tape - Google Patents

Abstract

The problem to be solved by the present invention is to provide a double-sided adhesive tape, which can be well attached to various parts with three-dimensional curved surfaces, especially parts for electronic equipment, and can provide good impact resistance and water resistance even if it is processed into a narrow width. and reworkability. The solution of the present invention is a double-sided adhesive tape, which has one or two or more adhesive layers on both sides of the substrate directly or through other layers, and is characterized in that: among the adhesive layers, the most The storage elastic modulus of the outer adhesive layer (1) at 25°C is 50~200kPa, the glass transition temperature (Tg) of the adhesive layer (2) other than the outermost layer is below 0°C, and the thickness of the substrate layer 3~30μm.

Description

double sided adhesive tape

The present invention relates to a double-sided adhesive tape that can be used in the production of various items represented by electronic devices such as navigation systems, computers, televisions, and smartphones.

Double-sided adhesive tapes used in portable electronic devices such as smartphones require impact resistance that does not peel off due to impacts such as when the device is dropped. Therefore, the double-sided adhesive tape used in this application needs to have a shock absorbing layer.

In addition, a waterproof function is required for portable electronic devices, and the double-sided adhesive tape used for fixing parts is also required to prevent water from entering. High bond strength. In addition, in recent years, more and more curved surfaces or complex-shaped panels are used from the viewpoint of design, and it is expected that the double-sided adhesive tape can not only be attached to unevenness or a large height difference, but also can be attached Performance on curved surfaces or complex shapes (Patent Document 1).

On the other hand, in the assembly process of an electronic device using a double-sided adhesive tape with a release paper on both sides, after peeling off one of the release papers of the double-sided adhesive tape, it is attached to the casing, along the direction perpendicular to the The pressure is applied in the direction of the attachment surface, and then the other release paper of the double-sided adhesive tape is peeled off and attached to the display, and the pressure is applied in the direction perpendicular to the attachment surface in the same way. When the bonding part of the display is a three-dimensional curved surface, because the force applied by the pressure will be vectorized, it is impossible to apply the same force to all positions of the attachment surface, and it is difficult to achieve complete attachment. Therefore, for three-dimensional curved surfaces, the accompanying property of the double-sided adhesive tape is greatly reduced. In the case where the double-sided adhesive tape is not completely attached to the case or the display, there is a problem that peeling occurs due to a slight gap in the area, and the gap becomes a path for water to enter, and there is a problem that the waterproof performance cannot be ensured.

In addition, foam double-sided adhesive tapes conventionally used for waterproofing portable electronic devices with flat displays cannot avoid the inclusion of relatively large air bubbles called voids due to their manufacturing methods. In recent years, due to the expansion of the display portion of portable electronic equipment, the junction between the display and the casing has become narrower. If the tape width is smaller than the air bubble diameter, it will become a water entry path and lose waterproofness.

In addition, it is considered that by making a double-sided adhesive tape obtained by using a soft resin layer instead of a foam base material and laminating an adhesive layer with good adhesion, in addition to achieving shock resistance, In addition to the accessory, it also achieves waterproofness in a narrow width. However, since the adhesive laminate system is easily torn during peeling, it is easy to remain on the adherend, so when it is damaged in the assembly process of portable electronic devices, it can be peeled off beautifully without reworkability of residue There will be problems. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2015-98554

[Problem to be Solved by the Invention]

The problem to be solved by the present invention is to provide a double-sided adhesive tape, which can be well attached to various parts with three-dimensional curved surfaces, especially parts for electronic equipment, and can still provide good shock resistance, water resistance and reworkability. [Means to solve the problem]

The inventors of the present invention found that by laminating a shock-absorbing adhesive layer on one or both sides of the substrate, and laminating an adhesive layer with good adhesion on the outermost layers of the front and back sides, even if the width is narrow, the adhesion , shock resistance, water resistance and reworkability are still excellent double-sided adhesive tape.

That is, the present invention relates to a double-sided adhesive tape, which has one or more adhesive layers on both sides of the substrate directly or through other layers, and is characterized in that: among the adhesive layers, the most The storage elastic modulus of the outer adhesive layer (1) at 25°C is 50~200kPa, the glass transition temperature (Tg) of the adhesive layer (2) other than the outermost layer is below 0°C, and the thickness of the substrate layer 3~30μm. [Effect of Invention]

The double-sided adhesive tape of the present invention exhibits proper adhesion to the adherend with a three-dimensional curved surface, and can effectively prevent water from entering through the adhesion gap even if the width is narrow, and has an excellent waterproof function. In addition, even if the electronic device is subjected to a shock when the electronic device is dropped, it will not peel off, and the adhesive tape will not be torn when the electronic device is disassembled, and can be easily disassembled. Therefore, even with advances in advanced design, waterproof performance and shock resistance performance can be effectively imparted to electronic devices having a three-dimensional curved surface at the joint between the case and the display.

The double-sided adhesive tape of the present invention is attached to both sides of the substrate directly or through other layers, each having one or more than two adhesive layers, and is characterized in that: among the adhesive layers, the outermost adhesive The storage elastic modulus of layer (1) at 25°C is 50~200kPa, the glass transition temperature (Tg) of the adhesive layer (2) other than the outermost layer is below 0°C, and the thickness of the substrate layer is 3~30μm .

[adhesive layer] The storage elastic modulus of the outermost adhesive layer (1) of the double-sided adhesive tape of the present invention is 50-200kPa at 25°C, preferably 52-150kPa, more preferably 55-100kPa, further preferably 60-90kPa . By selecting the storage elastic modulus at 25°C from the above-mentioned range, it is possible to achieve appropriate adherence to three-dimensional curved surfaces, and to achieve good reprocessing where the adhesive does not remain on the adherend when it is peeled off by hand sex.

The glass transition temperature (Tg) of the adhesive layer (2) other than the outermost surface is below 0°C, preferably -40~0°C, more preferably -30~-5°C, especially preferably -20~-10°C. By setting the glass transition temperature (Tg) of the adhesive layer other than the outermost surface within the above-mentioned range, when an electronic device etc. bonded by a double-sided adhesive tape is dropped, the impact can be properly absorbed to prevent peeling.

In addition, the thickness of each adhesive layer is preferably 1-100 μm, more preferably 5-90 μm, further preferably 20-80 μm. By making the thickness of the adhesive layer into this range, it can exhibit appropriate adhesive force.

(adhesive composition) The adhesive composition constituting the adhesive layer of the double-sided adhesive tape of the present invention may be any adhesive composition generally used in double-sided adhesive tapes as long as it can form an adhesive layer having the above characteristics. As for the adhesive composition, the following acrylic adhesive composition can be suitably used: acrylic acid composed of a single (meth)acrylate or a copolymer of (meth)acrylate and other monomers It is an acrylic adhesive composition obtained by blending additives such as adhesion-imparting resin or cross-linking agent, etc., to the base polymer based on a copolymer.

Examples of (meth)acrylate monomers that can be used in the production of the acrylic copolymer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate , Isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, (meth) ) cyclohexyl acrylate, 2-ethylhexyl methacrylate, and the like, and one or more of these can be used. Among them, it is preferable to use (meth)acrylates with an alkyl group of 1 to 12 carbons, more preferably to use (meth)acrylates with an alkyl group of 4 to 8 carbons, use n-butyl acrylate, acrylic acid-2 -Ethylhexyl ester, either or both, is preferable since it is easy to secure the adhesion with the adherend and has excellent cohesive force.

With respect to the total amount of monomers used in the production of the above-mentioned acrylic copolymer, the above-mentioned (meth)acrylate monomer is preferably used in an amount of 60% by mass or more, more preferably in the range of 80% by mass to 98.5% by mass, and in the range of 90% by mass The range of %~98.5% by mass is more preferable because it is easy to ensure the adhesion with the adherend and the cohesion is excellent.

For other monomers, highly polar vinyl monomers are suitable, especially vinyl monomers with hydroxyl groups, vinyl monomers with carboxyl groups, and vinyl monomers with amide groups. These other monomers can be used alone or in combination of two or more.

As the vinyl monomer having a hydroxyl group, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, Hydroxyl-containing (meth)acrylates such as 6-hydroxyhexyl (meth)acrylate.

As the vinyl monomer having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth)acrylic acid dimer, crotonic acid, etc. can be used, among which acrylic acid is preferably used.

啉、丙烯酸醯胺、N,N-二甲基丙烯酸醯胺等。For vinyl monomers having amide groups, N-vinylpyrrolidone, N-vinylcaprolactam, acrylamide

Phyline, Acrylamide, N,N-Dimethacrylamide, etc.

As far as other highly polar vinyl monomers are concerned, besides the above-mentioned ones, vinyl acetate, ethylene oxide modified succinic acid acrylate, 2-acrylamide-2-methylpropanesulfonic acid, etc. Acid-based monomers, etc.

The content of the above-mentioned other monomers is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and still more preferably 2.5 to 10% by mass in the monomer components constituting the acrylic copolymer. When the content is within this range, it is easy to secure the adhesiveness with the adherend, and the cohesive force is excellent, so it is preferable.

When using a cross-linking agent described later as the adhesive, it is preferable to use an acrylic polymer having a functional group that reacts with a functional group of the cross-linking agent as the acrylic polymer. As a functional group which the said acrylic polymer may have, a hydroxyl group is mentioned, for example.

The above-mentioned hydroxyl group can be introduced into an acrylic polymer by using, for example, a vinyl monomer having a hydroxyl group as the above-mentioned monomer. In addition, when an isocyanate-based cross-linking agent is used as the cross-linking agent, the vinyl monomer having a hydroxyl group is preferable as a vinyl monomer having a functional group that can react with it, especially (meth)acrylic acid-4 -Hydroxybutyl ester, 6-hydroxyhexyl (meth)acrylate. The content of the vinyl monomer having a hydroxyl group reactive with the isocyanate-based crosslinking agent is preferably 0.01 to 1.0% by mass of the monomer components constituting the acrylic copolymer, more preferably 0.03 to 0.6% by mass, especially preferably 0.05% by mass %~0.3% by mass.

Acrylic copolymers can be obtained by copolymerization using known polymerization methods such as solution polymerization, block polymerization, suspension polymerization, and emulsion polymerization. In consideration of the water resistance of the adhesive, solution polymerization or block polymerization. The initiation method of polymerization can also be arbitrarily selected, and the initiation by heat using peroxide-based thermal polymerization initiators such as benzoyl peroxide and lauryl peroxide, and azo-based thermal polymerization initiators such as azobisisobutyronitrile method, or the initiation method by ultraviolet irradiation using acetophenone-based, benzoin ether-based, benzyl ketal-based, acylphosphine oxide-based, benzoin-based, or benzophenone-based photopolymerization initiators, Or the method caused by irradiation of electron beams.

The molecular weight of the above-mentioned acrylic copolymer is determined by gel permeation chromatography (GPC), and the weight average molecular weight in terms of standard polystyrene is 400,000 to 3 million, and it is more suitable to use 600,000 to 2 million. The weight average molecular weight.

In addition, the said weight average molecular weight means the value calculated by the gel permeation chromatography method (GPC method) and performing standard polystyrene conversion. Specifically, the weight average molecular weight can be measured under the following conditions using a GPC device (HLC-8320GPC) manufactured by Tosoh Corporation.

Sample concentration: 1.0% by mass (tetrahydrofuran solution) Sample injection volume: 100μL Eluent: Tetrahydrofuran Flow rate: 0.8mL/min Measuring temperature: 40°C Main column: TSKgel GMHHR-H(S) 2 pieces Guard column: TSKguradcolumn HHR(S) Detector: Differential refractometer Weight average molecular weight of standard polystyrene: 10,000 to 20 million (manufactured by Tosoh Co., Ltd.)

In the acrylic adhesive composition used in the present invention, in order to improve the adhesiveness with the adherend, it is preferable to use an adhesion-imparting resin. Examples of tack-imparting resins include rosin, polymerized rosin, polymerized rosin ester, rosin phenol, stabilized rosin ester, disproportionated rosin ester, hydrogenated rosin ester, terpene, and terpene phenol. resins, petroleum resins, (meth)acrylate resins, etc. When used in an emulsified adhesive composition, it is advisable to use an emulsified adhesive resin.

Among them, disproportionated rosin ester-based tackifying resins, polymerized rosin ester-based tackifying resins, rosin-phenol-based tackifying resins, hydrogenated rosin ester-based tackifying resins, (meth)acrylate-based resins, terpene-phenolic resins, Petroleum resin.

As for the above-mentioned tackifying resin, it is preferable to use one with a softening point in the range of 30°C to 180°C, and one with a softening point in the range of 70°C to 140°C is preferable because it is easy to ensure adhesion with the adherend and has excellent cohesive force. When using the above-mentioned (meth)acrylate tackifying resin, the (meth)acrylate tackifying resin preferably has a glass transition temperature of 30°C to 200°C, more preferably 50°C to 160°C.

The blending ratio of the acrylic copolymer and the tackifying resin is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, based on 100 parts by mass of the tackifying resin based on 100 parts by mass of the acrylic copolymer. By making the ratio of both into this range, it becomes easy to ensure the adhesiveness with an adherend.

In the acrylic adhesive composition, in order to improve the cohesion of the adhesive layer, the adhesive should be cross-linked. As such a crosslinking agent, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, a metal chelate type crosslinking agent, an aziridine type crosslinking agent etc. are mentioned. Among them, a crosslinking agent of the type that is added after the completion of the polymerization to advance the crosslinking reaction is preferable, and an isocyanate crosslinking agent and an epoxy crosslinking agent that are highly reactive with (meth)acrylic copolymers are preferable. . Examples of isocyanate-based crosslinking agents include cresyl diisocyanate, 1,5-naphthyl diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and diisocyanate Xylyl ester, trimethylolpropane modified toluene diisocyanate, etc. In particular, trifunctional polyisocyanate compounds are preferred. Examples of the trifunctional isocyanate compound include toluene diisocyanate, trimethylolpropane tri-adducts thereof, triphenylmethane isocyanate, and the like.

As an indicator of the degree of crosslinking, the value of the gel fraction obtained by measuring the insoluble part after immersing the adhesive layer in toluene for 24 hours was used. The gel fraction is preferably 25 to 70% by mass, more preferably 30 to 60% by mass, and still more preferably 35 to 55% by mass. If it is the said range, it is easy to ensure the adhesiveness with an adherend, and since cohesive force is excellent, it is preferable.

In addition, the gel fraction was measured by the following method. Apply the above-mentioned adhesive to the release liner surface after drying so that the thickness after drying becomes 50 μm, dry at 100°C for 3 minutes, and then age at 40°C ( aging) for 2 days to form an adhesive layer. Cut the above-mentioned adhesive layer into a square with a length of 50 mm and a width of 50 mm as a test piece. After measuring the mass of the test piece (G1, excluding the release liner), the test piece was immersed in toluene for 24 hours in an environment of 23°C. After the immersion, the mixture of the test piece and toluene was filtered through a 300-mesh metal mesh to extract toluene-insoluble components. The mass (G2) obtained by drying the said insoluble component in 110 degreeC environment for 1 hour was measured. The gel fraction was calculated based on the mass (G1), mass (G2) and the following formula.

Gel fraction (mass%)=(G2/G1)×100 As the above-mentioned acrylic adhesive composition, in terms of additives, plasticizers, softeners, antioxidants, fillers such as glass or plastic fibers, balloons, beads, and metal powders, pigments, and dyes can be optionally added as required. Colorants, leveling agents, tackifiers, water repellents, defoamers and other known agents are added to the acrylic adhesive composition.

The temperature indicated by the peak value of the loss tangent (tanδ) of the adhesive layer used in the double-sided adhesive tape of the present invention at a frequency of 1 Hz is preferably -40°C~15°C, more preferably -20°C~5°C. By setting the peak value of the loss tangent of the adhesive layer within this range, it becomes easy to provide good adhesion to an adherend at normal temperature.

The above loss tangent (tanδ) is obtained from the storage elastic modulus (G') and the loss elastic modulus (G'') obtained from the dynamic viscoelasticity measurement by temperature dispersion, by tanδ=G''/G' The formula is obtained. The temperature represented by the peak value of the loss tangent (tan δ) at a frequency of 1 Hz was obtained from the dynamic viscoelasticity measurement by temperature dispersion.

In addition, the 25°C storage elastic modulus of the adhesive layer of the double-sided adhesive tape of the present invention is 50-200kPa, preferably 52-150kPa, more preferably 55-100kPa, and further preferably 60-90kPa. This is because, when the storage elastic modulus of the adhesive layer is extremely high, the adhesion to the three-dimensional curved surface is reduced, and in the case of the storage elastic modulus of the adhesive layer is extremely low, the cohesive force decreases and the Reduced peel resistance.

By appropriately selecting the type or ratio of the monomers used in the copolymer constituting the adhesive, the type or amount of the polymerization initiator, the type or amount of the crosslinking agent or the adhesion-imparting resin, the polymerization method, etc. to adjust the dynamic viscoelastic properties.

In addition, the dynamic viscoelastic properties of the above-mentioned adhesive layer are defined by using the loss tangent, or loss tangent and storage elastic modulus of the dynamic viscoelastic spectrum at a specific frequency and a specific temperature, and further using the dynamic viscoelastic spectrum in a specific frequency The temperature represented by the peak of the loss tangent of the graph, or the peak value of the loss tangent is defined. In the measurement of dynamic viscoelasticity, a viscoelasticity testing machine (manufactured by TA Instruments Japan Inc., trade name: ARES G2) was used to hold a test piece (diameter 8 mm, formed into an adhesive layer with a thickness of about 2 mm) between the same The storage elastic modulus (G') and the loss elastic modulus (G'') are measured at a frequency of 1 Hz from -50°C to 150°C between parallel discs made of stainless steel with a diameter of 8 mm in the measuring part of the testing machine.

The thickness of the adhesive layer of the double-sided adhesive tape of the present invention is preferably 10-100 μm on one side, more preferably 25-80 μm, considering that it is easy to ensure the adhesion with the adherend when it is made into a thin tape.

[Substrate] The thickness of the substrate of the double-sided adhesive tape of the present invention is 3-30 μm, preferably 4-20 μm, more preferably 5-15 μm. By using a base material having a thickness in this range, even in the combination of rigid bodies having a three-dimensional curved surface shape, excellent adhesion without creating voids into which water or the like can enter can be realized.

In terms of the breaking strength of the above base material, it is preferably 4~85N/10mm, more preferably 7~80N/10mm, and further preferably 8~35N/10mm. At this time, the breaking strength was set to the maximum value of the tensile strength obtained by performing a tensile test on a base material with a width of 10 mm at 300 m/min. When a base material having a breaking strength within this range is selected, the base material will not be torn even when the double-sided adhesive tape is peeled off by hand. In addition, by having a certain degree of rigidity, the rebound of the base material is small, and it has excellent adhesion that can be properly attached even to an adherend having a three-dimensional curved surface shape, a concave-convex shape, or a rough surface.

In addition, the type of the above-mentioned base material is not particularly limited, for example, polyolefin resin films such as polyethylene film, polypropylene film, ethylene-propylene copolymer film, ethylene-vinyl acetate copolymer film, and polyurethane film can be used. Ester resin film, acrylic resin film, rubber film made of elastomer, etc., polyethylene foam sheet, polypropylene foam sheet, ethylene-propylene copolymer foam sheet, Polyolefin foam sheets such as ethylene-vinyl acetate copolymer foam sheets, polyurethane foam sheets, acrylic foam sheets, and the like. Among these substrates, polyester films, polyurethane resin films, and acrylic resin films are preferred from the standpoint of dimensional stability and shock resistance when the double-sided adhesive tape is processed into a window frame shape with a narrow width. Resin film, polyolefin foam sheet, polyurethane foam sheet, acrylic foam sheet. In addition, these substrates may be used singly or by laminating two or more kinds.

[Double-sided adhesive tape] The double-sided adhesive tape of the present invention, by using the above-mentioned adhesive layer and base material, can exhibit proper adhesion to the adherend with a three-dimensional curved surface, and can effectively prevent water from coming in especially when used for fixing parts of electrical equipment. Close gaps enter, with excellent waterproof function.

The double-sided adhesive tape of the present invention is basically constituted by providing adhesive layers on both sides of the substrate. The base material and the adhesive layer can be laminated directly, or other layers can be interposed. Specifically, it can be composed of 5 layers of adhesive layer (1)-adhesive layer (2)-substrate-adhesive layer (2)-adhesive layer (1), or it can be adhesive layer (1) -adhesive layer (2)-substrate-adhesive layer (1) consists of 4 layers. In addition, if the storage elastic modulus at 25°C is 50~200kPa, and the glass transition temperature (Tg) is below 0°C, the adhesive system can be applied to both the adhesive layer (1) and the adhesive layer (2). . That is, the adhesive layer (1) and the adhesive layer (2) can be laminated with the same adhesive layer.

These aspects can be appropriately selected according to the purpose of use. In the case of giving the tape more dimensional stability or tensile strength, a laminated layer such as polyester film can be provided, and in the case of giving the tape concealment or light-shielding properties, it can be provided. A light-shielding layer may be provided with a light-reflecting layer when light reflectivity is ensured. When providing such another layer, you may use a waterproof layer as this other layer.

As the light-shielding layer, inks containing colorants such as pigments can be easily used, and layers made of black inks are preferably used because of their excellent light-shielding properties. As the reflective layer, a layer formed of white ink can be used easily. The thickness of these layers is preferably 2 to 20 μm, more preferably 3 to 10 μm, particularly preferably 4 to 6 μm. When the thickness is within this range, curling of the base material due to hardening and shrinkage of the ink is less likely to occur, and the processability of the tape becomes good.

The double-sided adhesive tape of the present invention can be manufactured by known and commonly used methods. For example, a direct printing method in which an acrylic adhesive composition is directly applied to a substrate and allowed to dry, or applied to the surface of another layer laminated on a substrate and allowed to dry, or an acrylic adhesive A transfer method in which the composition is coated on a release sheet, dried, and then attached to the surface of a substrate or other layers.

The thickness of the double-sided adhesive tape of the present invention can be adjusted appropriately according to the usage, and it is 70-1400 μm. For fixing parts of electronic equipment, especially in the case of small and thin portable electronic equipment, since a thin tape thickness is required, it should be 80~1000μm, more preferably 100~500μm, especially 200μm~400μm. By setting the thickness of the tape to this thickness, it is easy to ensure the adhesion with the adherend even for thin and small portable electronic devices, and it has excellent cohesive force, so it is suitable for use, and a good waterproof function can also be realized.

The double-sided adhesive tape of the present invention exhibits proper adhesion to the adherend, can effectively prevent water from entering through the adhesion gap, and has excellent waterproof function. Therefore, the waterproof function can be effectively imparted to portable electronic devices such as portable electronic devices where it is difficult to install other waterproof mechanisms due to the progress in thickness reduction and the strict limitation of the capacity in the casing. In terms of specific usage, for example, it can be suitably used as the protective panel of the information display part in electronic notebooks, mobile phones, smart phones, tablet terminals, PHS, cameras, music players, etc. Bonding with the casing, bonding of the casings with each other, bonding of the casing with input devices such as tablet numeric keypads or touch panels, bonding of the casing with decorative sheets, and bonding of various other parts or modules fixed etc. [Example]

Examples are specifically described below, but the present invention is not limited to these Examples.

(Preparation of Adhesive A) Add 95.9 parts by mass of n-butyl acrylate, 4 parts by mass of acrylic acid, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 200 parts by mass of ethyl acetate into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen gas introduction tube, and a thermometer , while stirring, the temperature was raised to 72° C. while blowing nitrogen gas.

To this mixture, 2 parts by mass of 2,2'-azobis(2-methylbutyronitrile) solution previously dissolved in ethyl acetate (0.1 mass % of solid content) was added, and the mixture was maintained at 72° C. for 4 hours while stirring. After 1 hour, it was maintained at 75°C for 5 hours. By filtering with a 200-mesh metal mesh, an acrylic polymer solution A (33.3% by mass of non-volatile matter) having a weight average molecular weight of 1,040,000 was obtained.

Then, 10 parts by mass of the above-mentioned acrylic polymer A, polymerized rosin ester-based tackifying resin D-125 (manufactured by Arakawa Chemical Co., Ltd.) and disproportionated rosin ester-based tackifying resin A-100 (manufactured by Arakawa Chemical Co., Ltd.) ) Co., Ltd.) 10 parts by mass were mixed and stirred, and ethyl acetate was added to obtain an adhesive solution A with a solid content of 38%.

With respect to 100 parts by mass of the above-mentioned adhesive solution A, BURNOCK D-40 (manufactured by DIC Co., Ltd., a trimethylolpropane adduct of diisocyanate cresyl) was added as a crosslinking agent, and the isocyanate group content was 7 % by mass, non-volatile content (40% by mass) 1.2 parts by mass, stirring and mixing to make it uniform, and then filtering with a 100-mesh metal mesh to obtain the adhesive A.

(Preparation of Adhesive B) In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, add 60.94 parts by mass of n-butyl acrylate, 35 parts by mass of 2-ethylhexyl acrylate, 4 parts by mass of acrylic acid, and 4-hydroxybutyl acrylate. 0.06 mass parts of esters and 200 mass parts of ethyl acetate were heated up to 72 degreeC, blowing in nitrogen gas, with stirring.

To the above mixture, 2 parts by mass of 2,2'-azobis(2-methylbutyronitrile) solution (solid content: 0.1 mass%) previously dissolved in ethyl acetate was added, and the mixture was maintained at 72°C for 4 After 1 hour, it was maintained at 75°C for 5 hours. By filtering with a 200-mesh metal mesh, an acrylic polymer solution B (33.3% by mass of non-volatile matter) having a weight average molecular weight of 900,000 was obtained.

5 parts by mass of the above-mentioned acrylic polymer B, polymerized rosin ester-based adhesion-imparting resin D-125 (manufactured by Arakawa Chemical Industry Co., Ltd.), and disproportionated rosin ester-based adhesion-imparting resin A-100 (manufactured by Arakawa Chemical Industry Co., Ltd.) 10 parts by mass) were mixed and stirred, and ethyl acetate was added to obtain an adhesive solution B with a solid content of 31%.

With respect to 100 parts by mass of the above-mentioned adhesive solution B, BURNOCK D-40 (manufactured by DIC Co., Ltd., a trimethylolpropane adduct of diisocyanate cresyl) was added as a crosslinking agent, and the isocyanate group content was 7 % by mass, non-volatile content (40% by mass) 2.4 parts by mass, stirred and mixed to make it uniform, and then obtained the adhesive B by filtering with a 100-mesh metal mesh.

(Preparation of Adhesive C) Add 80.94 parts by mass of n-butyl acrylate, 5 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of cyclohexyl acrylate, and 4 parts by mass of acrylic acid parts, 0.06 parts by mass of 4-hydroxybutyl acrylate, and 200 parts by mass of ethyl acetate were heated up to 72°C while blowing nitrogen gas under stirring.

To the above mixture, 2 parts by mass of 2,2'-azobis(2-methylbutyronitrile) solution (solid content: 0.1% by mass) previously dissolved in ethyl acetate was added, and the mixture was maintained at 72°C for 4 After 1 hour, it was maintained at 75°C for 5 hours. By filtering with a 200-mesh metal mesh, an acrylic polymer solution C (33.3% by mass of non-volatile matter) having a weight average molecular weight of 1,200,000 was obtained.

Then, 5 parts by mass of the above-mentioned acrylic polymer C, polymerized rosin ester-based tackifying resin D-125 (manufactured by Arakawa Chemical Co., Ltd.), and disproportionated rosin ester-based tackifying resin A-100 (manufactured by Arakawa Chemical Co., Ltd.) After mixing and stirring 15 parts by mass manufactured by the company, ethyl acetate was added to obtain an adhesive solution C having a solid content of 31%.

With respect to 100 parts by mass of the above-mentioned adhesive solution C, BURNOCK D-40 (manufactured by DIC Co., Ltd., a trimethylolpropane adduct of diisocyanate cresyl) was added as a crosslinking agent, and the isocyanate group content was 7 % by mass, non-volatile content (40% by mass) 1.0 parts by mass, stirred and mixed to make it uniform, and then obtained adhesive C by filtering with a 100-mesh metal mesh.

(Preparation of Adhesive D) To 100 parts by mass of SK-Dyne 2094 (manufactured by Soken Chemical Co., Ltd.), BURNOCK D-40 (manufactured by DIC Co., Ltd., a trimethylolpropane adduct of diisocyanate cresyl) was added as a crosslinking agent, and the isocyanate group contained 7% by mass, 40% by mass of non-volatile matter) 1.2 parts by mass, stirred and mixed to make it uniform, and obtained the adhesive D by filtering with a 100-mesh metal mesh.

(Preparation of Adhesive E) To 100 parts by mass of the above-mentioned acrylic polymer solution A (non-volatile content 33.3% by mass), BURNOCK D-40 (manufactured by DIC Co., Ltd., trimethylolpropane addition of cresyl diisocyanate) was added as a crosslinking agent The product, isocyanate group content rate 7% by mass, non-volatile matter 40% by mass) 1.2 mass parts, after stirring and mixing to make it uniform, the adhesive agent E was obtained by filtering with a 100-mesh metal mesh.

(Preparation of Adhesive F) To 100 parts by mass of SK-Dyne 1502C (manufactured by Soken Chemical Co., Ltd.), BURNOCK D-40 (manufactured by DIC Co., Ltd., a trimethylolpropane adduct of diisocyanate cresyl) was added as a crosslinking agent, and the isocyanate group contained 7% by mass, 40% by mass non-volatile matter) 1.5 parts by mass, stirred and mixed to make it uniform, and then filtered through a 100-mesh metal mesh to obtain the adhesive F.

(Example 1) The above-mentioned adhesive A was coated on the surface of a silicone-treated release liner (manufactured by Sumika Paper Co., Ltd.) using a coating bar so that the thickness of the adhesive layer after drying was 62 μm. It was dried at 80°C for 3 minutes to obtain an adhesive layer (1). In the same way, an adhesive layer (2) was formed on the surface of a silicone-treated release liner (manufactured by Sumika Paper Co., Ltd.) so that the thickness of the above-mentioned adhesive B after drying became 60 μm. .

Then, attach the above-mentioned adhesive layer (2) to both sides of a polyester film base material with a thickness of 6 μm, and attach the above-mentioned adhesive layer (1) to the two sides to make it the outermost layer, and then maintain it in an environment of 40°C After 48 hours, a double-sided adhesive tape with a thickness of 250 μm was produced.

(Example 2) Except having used the polyester film base material of thickness 12 micrometers instead of the polyester film base material of thickness 6 micrometers, it was the method similar to Example 1, and the double-sided adhesive tape was produced.

(Example 3) In the adhesive agent layer (2), except having used the adhesive agent C instead of the adhesive agent B, it carried out similarly to Example 1, and produced the double-sided adhesive tape.

(Example 4) In the adhesive agent layer (2), except having used the adhesive agent C instead of the adhesive agent B, it carried out similarly to Example 2, and produced the double-sided adhesive tape.

(Example 5) In the adhesive layer (1), the adhesive B was used instead of the adhesive A, and in the adhesive layer (2), the adhesive A was used instead of the adhesive B. In addition, the same method as in Example 1 was used to make a double Adhesive tape.

(Example 6) In the adhesive agent layer (2), except having used the adhesive agent C instead of the adhesive agent A, it manufactured the double-sided adhesive tape by the method similar to Example 5.

(Example 7) In the adhesive agent layer (1), except having used the adhesive agent C instead of the adhesive agent B, it manufactured the double-sided adhesive tape by the method similar to Example 5.

(Embodiment 8) In the adhesive agent layer (2), except having used the adhesive agent B instead of the adhesive agent A, the double-sided adhesive tape was produced by the method similar to Example 5.

(Example 9) The above-mentioned adhesive A was coated on the surface of a silicone-treated release liner (manufactured by Sumika Paper Co., Ltd.) using a coating bar so that the thickness of the adhesive layer after drying became 77 μm. It was dried at 80°C for 3 minutes to make the adhesive layer (1). In the same manner, an adhesive layer (2) was formed on the surface of a silicone-treated release liner (manufactured by Sumika Paper Co., Ltd.) so that the thickness of the adhesive B after drying became 90 μm.

Then, stick the above-mentioned adhesive layer (2) on one side of the polyester film substrate with a thickness of 6 μm, and stick the above-mentioned adhesive layer (1) on both sides to make it the outermost layer. Under curing for 48 hours to make a double-sided adhesive tape with a thickness of 250 μm.

(comparative example 1) Except having used the polyester film base material of thickness 2 micrometers instead of the polyester film base material of thickness 6 micrometers, it was the same method as Example 1, and the double-sided adhesive tape was produced.

(comparative example 2) Except having used the polyester film base material of thickness 38 micrometers instead of the polyester film base material of thickness 6 micrometers, it was the same method as Example 1, and the double-sided adhesive tape was produced.

(comparative example 3) In the adhesive agent layer (1), except having used the adhesive agent D instead of the adhesive agent B, the double-sided adhesive tape was produced by the method similar to Example 5.

(comparative example 4) In the adhesive agent layer (1), except having used the adhesive agent E instead of the adhesive agent B, the double-sided adhesive tape was produced by the method similar to Example 5.

(comparative example 5) In the adhesive agent layer (2), except having used the adhesive agent F instead of the adhesive agent B, it manufactured the double-sided adhesive tape by the method similar to Example 1.

(comparative example 6) The above-mentioned adhesive A was coated on the surface of a silicone-treated release liner (manufactured by Sumika Paper Co., Ltd.) using a coating bar so that the thickness of the adhesive layer after drying became 25 μm. ℃ drying for 3 minutes to make the adhesive A layer. Then, the above-mentioned adhesive A layer was pasted on both sides of the polyolefin-based foam substrate A with a thickness of 200 μm, and cured at 40° C. for 48 hours to produce a double-sided adhesive tape with a thickness of 250 μm.

(Accompanying, waterproof test) Cut the double-sided adhesive tapes produced in the examples and comparative examples into an outer diameter of 136mm×66mm, a width of 0.5mm, and a curvature of four corners of the outer diameter of 4mm, and make a frame-shaped sample as shown in Figure 1. . After sticking to the acrylic adherend A shown in Figure 2 and Figure 3, stick it to the acrylic adherend B shown in Figure 4, and pressurize with a pressure of 20N/ ^cm2 for 10 seconds, What was left still for 24 hours was used as a test piece. However, the parts of the adherend A and the adherend B to which the frame-like samples are attached are three-dimensional curved surfaces.

After leaving the test piece at a depth of 1m for 30 minutes (according to IPX7 of JISC0920), evaluate whether there is water entering the frame of the frame-shaped double-sided adhesive tape. ○: No water ingress, good attachment to three-dimensional curved surfaces ×: There is water ingress, and the attachment to three-dimensional curved surfaces is not good

(reprocessing test) Disassemble the sample used in the waterproof test, and peel off the double-sided adhesive tape by hand. At this time, check whether the adhesive tape is torn or whether there is residual glue remaining on the adherend. ○: No tearing and no glue residue ×: There is tearing, or there is residual glue

(shock resistance test) The double-sided adhesive tapes obtained in Examples and Comparative Examples were cut to make two adhesive tapes with a width of 5 mm and a length of 400 mm. Then, in an environment with a temperature of 23°C and a relative humidity of 50%RH, the above two pieces of adhesive tape were attached to a flat surface with a thickness of 2mm, a width of 50mm, and a length of 50mm in such a way that there was an interval of 45mm in the width direction. One side of the acrylic board (MITSUBISHI CHEMICAL CORPORATION, Acrylite MR200 "trademark", hue: transparent) (Figure 5).

Then, place an acrylonitrile butadiene styrene plate (ABS plate, thickness 2mm, width 100mm and length 150mm) on the surface of the adhesive tape, and roll it back and forth once on the surface with a 5kg roller, and heat it at 23°C and relative humidity. The test piece was obtained by standing still for 24 hours under the environment of 50%RH (FIG. 6). Then set a ㄇ-shaped measuring platform (made of aluminum with a thickness of 5mm) with a length of 150mm, a width of 100mm, and a height of 45mm on the base of a Dupont-type impact tester (manufactured by TESTER SANGYO CO,. LTD.), and the above-mentioned test piece is formed by The acrylic plate is placed on the ㄇ-shaped measuring platform with the acrylic plate facing down (Figure 7). Then, from the side of the above-mentioned ABS plate, a hammer core made of stainless steel with a diameter of 25 mm and a mass of 300 g was dropped 5 times from a height of 10 cm.

In the above test, the drop height was increased step by step by 10cm and the test was repeated, and the impact resistance of the adhesive tape was evaluated based on the drop height (cm) when the peeling of the adhesive tape or the separation of the acrylic sheet was confirmed. sex. ◯: The above-mentioned drop height is 70 cm or more. ×: The above-mentioned drop height is less than 70 cm.

【Table 1】

【Table 2】

【table 3】

【Table 4】

1‧‧‧Double-sided adhesive tape 2‧‧‧acrylic sheet 3‧‧‧ABS board 4‧‧‧ㄇ font measuring platform 5‧‧‧Hammer core

[Fig. 1] A plan view of a frame-shaped sample of the double-sided adhesive tape of the present invention. [Fig. 2] Plan view (lattice part is a curved shape) and cross-sectional view of the adherend A. [Fig. 3] A three-dimensional cross-sectional view of the adherend A. [Fig. 4] Plan view (lattice part is curved shape) and cross-sectional view of adherend B. [FIG. 5] An explanatory diagram of a sample for a shock resistance test of the double-sided adhesive tape of the present invention. [Fig. 6] An explanatory diagram of a sample for a shock resistance test of the double-sided adhesive tape of the present invention. [ Fig. 7 ] An explanatory diagram of a sample for a shock resistance test of the double-sided adhesive tape of the present invention.

Claims (6)

A double-sided adhesive tape, which is directly attached to both sides of a base material or through other layers, and has one or more than two layers of adhesive layers, and is characterized in that two or more layers of adhesive are provided on at least one side of the base material The adhesive layer, among the adhesive layers, the outermost adhesive layer (1) has a storage elastic modulus of 50 to 200 kPa at 25°C, and has adhesiveness at room temperature, and the adhesive layer other than the outermost layer (2) The glass transition temperature (Tg) is below 0°C, and the thickness of the substrate layer is 3-30 μm. For example, the double-sided adhesive tape of claim 1, wherein the adhesive constituting the adhesive layer is an acrylic adhesive composition containing an acrylic copolymer. For example, the double-sided adhesive tape of item 2 of the patent scope, wherein the weight average molecular weight of the acrylic copolymer is 400,000 to 3 million. The double-sided adhesive tape according to any one of claims 1 to 3 of the patent application, wherein the gel fraction of the adhesive constituting the adhesive layer is 25-70% by mass. For example, the double-sided adhesive tape of any one of items 1 to 3 in the scope of the patent application is attached to a three-dimensional curved surface. For example, the double-sided adhesive tape of any one of items 1 to 3 in the scope of the patent application is used for fixing parts of electronic equipment, and imparts waterproof performance to the fixed part of the electronic equipment.

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