JPWO2015041313A1 - Double-sided adhesive tape for portable electronic devices - Google Patents

Abstract

The present invention is for portable electronic devices that can adhere and fix components constituting a portable electronic device to the device main body, and the base material is not destroyed even when a strong impact is applied, and peeling of the component from the device main body can be suppressed. It aims at providing a double-sided adhesive tape. The present invention is a double-sided pressure-sensitive adhesive tape for portable electronic devices having adhesive layers on both sides of a base material, and the base material has a break elongation at 23 ° C. in the MD direction of 480 to 580% and an apparent density. A monomer comprising 0.4 to 0.6 g / cm3, a polyolefin foam having a 25% compressive strength in the thickness direction of 200 to 600 kPa, and at least one pressure-sensitive adhesive layer includes butyl acrylate and 2-ethylhexyl acrylate It is a double-sided pressure-sensitive adhesive tape for portable electronic devices containing 100 parts by weight of an acrylic copolymer having a weight average molecular weight of 400,000 to 1,000,000 obtained by copolymerizing a mixture and 30 to 50 parts by weight of a tackifier resin.

Description

The present invention is for portable electronic devices that can adhere and fix components constituting a portable electronic device to the device main body, and the base material is not destroyed even when a strong impact is applied, and peeling of the component from the device main body can be suppressed. It relates to a double-sided adhesive tape.

Mobile electronic devices such as mobile phones and personal digital assistants (PDAs) are designed so that they do not come off or break even if an impact is applied in consideration of falling from the user's hand to the foot. Fixed arrangements or device body designs are being considered. Therefore, a double-sided pressure-sensitive adhesive tape that is used for fixing the component to the main body of the device is desired to prevent the component from coming off even when an impact is applied, and not to apply a strong shock to the component. ing.

For example, in Patent Documents 1 and 2, an acrylic pressure-sensitive adhesive layer is laminated and integrated on at least one surface of a base material layer as a shock absorbing tape that fixes a component constituting a portable electronic device to the device body. An impact absorbing tape is described in which the layer is a cross-linked polyolefin resin foam sheet having a specific degree of cross-linking and an aspect ratio of cells.

However, in recent years, there has been a demand for a design that makes the portable electronic device thinner and lighter, and when the portable electronic device falls, a much stronger impact than ever is applied. Also, a strong impact may be applied depending on the environment in which the portable electronic device falls. For this reason, when such a strong impact was applied, the problem that components will peel from an apparatus main body has arisen.

JP 2009-242541 A JP 2009-258274 A

The present invention is for portable electronic devices that can adhere and fix components constituting a portable electronic device to the device main body, and the base material is not destroyed even when a strong impact is applied, and peeling of the component from the device main body can be suppressed. It aims at providing a double-sided adhesive tape.

The present invention is a double-sided pressure-sensitive adhesive tape for portable electronic devices having adhesive layers on both sides of a base material, and the base material has a break elongation at 23 ° C. in the MD direction of 480 to 580% and an apparent density. It is 0.4 to 0.6 g / cm ³ and is made of a polyolefin foam having a 25% compressive strength in the thickness direction of 200 to 600 kPa, and at least one pressure-sensitive adhesive layer contains butyl acrylate and 2-ethylhexyl acrylate A double-sided pressure-sensitive adhesive tape for portable electronic devices comprising 100 parts by weight of an acrylic copolymer having a weight average molecular weight of 400,000 to 1,000,000 obtained by copolymerizing a monomer mixture and 30 to 50 parts by weight of a tackifying resin. .
The present invention is described in detail below.

The present inventor has found that the cause of the peeling of the component from the device body when a strong impact is applied to the portable electronic device is the destruction of the substrate of the double-sided adhesive tape for portable electronic device, and the strength of the substrate Was considered to raise. However, when the strength of the base material is increased too much, the flexibility of the base material is remarkably impaired, causing a problem of peeling at the interface with the pressure-sensitive adhesive layer.
In response to such problems, the present inventor has obtained a 25 ° C. compressive elongation at 23 ° C. in the MD direction, an apparent density, and a 25% compression in the thickness direction of a polyolefin foam that is a base material for a double-sided pressure-sensitive adhesive tape for portable electronic devices. It has been found that by setting the strength within a specific range, both strength and flexibility can be improved. Furthermore, the present inventor has a pressure-sensitive adhesive layer having a high adhesive strength containing a specific acrylic copolymer and a tackifying resin on at least one surface of a substrate excellent in both strength and flexibility. It has been found that a double-sided pressure-sensitive adhesive tape for portable electronic devices has a base material that is not destroyed even when a strong impact is applied, and can suppress the peeling of components from the device body (that is, has excellent impact resistance). The present invention has been completed.

The present invention is a double-sided pressure-sensitive adhesive tape for portable electronic devices having pressure-sensitive adhesive layers on both sides of a substrate.
The base material has a breaking elongation at 23 ° C. in the MD direction of 480 to 580%, an apparent density of 0.4 to 0.6 g / cm ³ , and a 25% compressive strength in the thickness direction of 200 to 600 kPa. It consists of a certain polyolefin foam. By setting the breaking elongation at 23 ° C. in the MD direction, the apparent density, and the 25% compressive strength in the thickness direction of the polyolefin foam within the above ranges, both strength and flexibility can be improved.

The polyolefin foam has a breaking elongation at 23 ° C. in the MD direction of 480 to 580%. When the breaking elongation at 23 ° C. in the MD direction is less than 480%, the polyolefin foam is less flexible and easily peels off at the interface with the pressure-sensitive adhesive layer when a strong impact is applied. When the breaking elongation at 23 ° C. in the MD direction exceeds 580%, the polyolefin foam has a reduced strength and is easily broken when subjected to a strong impact. The preferable lower limit of 23 degreeC breaking elongation of MD direction is 505%, a preferable upper limit is 565%, a more preferable minimum is 510%, and a more preferable upper limit is 555%.
In addition, MD direction (machine direction) means the extrusion direction at the time of extruding a polyolefin foam in a sheet form. The elongation at break is obtained by measuring the elongation at break a (%) in accordance with JISK-6767 and correcting the measured elongation at break a (%) based on the following formula (1). Say.
Elongation at break (%) = Measured elongation at break a × (1 / (18 × b)) (1)
However, b represents the apparent density (g / cm < ³ >) of polyolefin foam.

The polyolefin foam has an apparent density of 0.4 to 0.6 g / cm ³ . When the apparent density is less than 0.4 g / cm ³ , the polyolefin foam has a reduced strength and is easily broken when subjected to a strong impact. When the apparent density exceeds 0.6 g / cm ³ , the polyolefin foam is less flexible and easily peels off at the interface with the pressure-sensitive adhesive layer when a strong impact is applied. The apparent lower limit of the density is 0.42 g / cm ^3, a preferred upper limit is 0.57 g / cm ^3, more preferable lower limit is 0.45 g / cm ^3, and a more preferred upper limit is 0.55 g / cm ^3.
The apparent density can be measured and calculated using an electronic hydrometer (trade name “ED120T”) manufactured by Mirage in accordance with JISK-6767.

The polyolefin foam has a 25% compressive strength in the thickness direction of 200 to 600 kPa. When the 25% compressive strength in the thickness direction is less than 200 kPa, the polyolefin foam is reduced in strength and easily broken when subjected to a strong impact. When the 25% compressive strength in the thickness direction exceeds 600 kPa, the polyolefin foam is less flexible and easily peels off at the interface with the pressure-sensitive adhesive layer when a strong impact is applied. The preferable lower limit of the 25% compressive strength in the thickness direction is 250 kPa, the preferable upper limit is 500 kPa, the more preferable lower limit is 300 kPa, and the more preferable upper limit is 400 kPa.
The 25% compressive strength in the thickness direction can be measured according to JISK-6767. For example, a 25 cm-thick laminate is produced by superimposing polyolefin foams cut into 5 cm × 5 cm and left at room temperature, and then the 25% compressive strength in the thickness direction of the laminate is measured at room temperature. .

The polyolefin foam is not particularly limited as long as it is a foam containing a polyolefin resin, and examples thereof include a polyethylene foam, a polypropylene foam, an ethylene-propylene foam, and the like. In order to adjust the breaking elongation, apparent density, and 25% compressive strength in the thickness direction to the above ranges, a polyolefin-based resin obtained using a metallocene compound containing a tetravalent transition metal as a polymerization catalyst is included. A foam (also referred to herein as a “metallocene polyolefin foam”) is preferred. Among these, a foam containing a polyethylene resin obtained by using a metallocene compound (also referred to as “metallocene polyethylene foam” in the present specification) is more preferable.
Examples of the metallocene compounds include Kaminsky catalysts.

As a polyethylene resin obtained using the metallocene compound contained in the metallocene polyethylene foam, for example, using the metallocene compound, ethylene and another α-olefin blended as necessary may be used. Examples thereof include polyethylene-based resins obtained by polymerization. Examples of the other α-olefin include propene, 1-butene, 1-pentene, 1-hexene and the like.

The metallocene polyethylene foam may further contain another olefin resin in addition to the polyethylene resin obtained using the metallocene compound. Examples of the other olefin-based resin include polyethylene, polypropylene, ethylene-propylene copolymer, and the like.
In this case, the content of the polyethylene resin obtained by using the metallocene compound in the metallocene polyethylene foam is preferably 40% by weight or more. When the content of the polyethylene resin obtained by using the metallocene compound is 40% by weight or more, high compressive strength can be obtained even if the metallocene polyethylene foam is thin.

The polyolefin foam is preferably cross-linked. By cross-linking the polyolefin foam, it is easy to adjust the breaking elongation at 23 ° C. in the MD direction, the apparent density, and the 25% compressive strength in the thickness direction to the above ranges.
The method for crosslinking the polyolefin foam is not particularly limited. For example, a method of irradiating the polyolefin foam with ionizing radiation such as electron beam, α ray, β ray, γ ray, Examples include a method of decomposing the organic peroxide by heating.

The method for producing the polyolefin foam is not particularly limited, but a foamable resin composition containing a polyolefin resin and a foaming agent is prepared, and the foamable resin composition is extruded into a sheet using an extruder. In this case, it is preferable to foam the foaming agent and crosslink the obtained polyolefin foam as necessary.

Although the thickness of the said polyolefin foam is not specifically limited, 120-300 micrometers is preferable. When the thickness is less than 120 μm, the polyolefin foam has a reduced strength and may be destroyed when a strong impact is applied. When the thickness exceeds 300 μm, the polyolefin foam is reduced in flexibility, and may be peeled off at the interface with the pressure-sensitive adhesive layer when a strong impact is applied. Also, along the shape of the adherend It may be difficult to stick them together.

In the double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention, at least one pressure-sensitive adhesive layer has a weight average molecular weight of 400,000 to 1,000,000 obtained by copolymerizing a monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate. Contains 100 parts by weight of an acrylic copolymer and 30-50 parts by weight of a tackifying resin. By setting it as such a composition, the adhesive force of an adhesive layer can be raised.
In the double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention, as long as at least one pressure-sensitive adhesive layer has such a composition, the double-sided pressure-sensitive adhesive layers may have the same composition or different compositions. May be.

The acrylic copolymer is obtained by copolymerizing a monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate.
The preferable content of butyl acrylate in the total monomer mixture is 40 to 80% by weight. When the content of butyl acrylate is less than 40% by weight, the pressure-sensitive adhesive layer becomes too soft and the cohesive force is lowered, and may be peeled off when a strong impact is applied. When the content of butyl acrylate exceeds 80% by weight, the pressure-sensitive adhesive layer becomes hard and the adhesive strength or tack is lowered, and may be peeled off when a strong impact is applied.
The preferable content of 2-ethylhexyl acrylate in the total monomer mixture is 10 to 40% by weight. When the content of 2-ethylhexyl acrylate is less than 10% by weight, the pressure-sensitive adhesive layer may be peeled off when the adhesive force is reduced and a strong impact is applied. When the content of 2-ethylhexyl acrylate exceeds 40% by weight, the pressure-sensitive adhesive layer becomes too soft and the cohesive force is lowered, and may be peeled off when a strong impact is applied.

The monomer mixture may contain other polymerizable monomers other than butyl acrylate and 2-ethylhexyl acrylate as necessary.
Examples of other polymerizable monomers that can be copolymerized include, for example, carbon number of alkyl groups such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth) acrylate. 1 to 3 (meth) acrylic acid alkyl ester, tridecyl methacrylate, and (meth) acrylic acid alkyl ester having 13 to 18 carbon atoms such as stearyl (meth) acrylate, hydroxyalkyl (meth) acrylate , Glycerin dimethacrylate, glycidyl (meth) acrylate, 2-methacryloyloxyethyl isocyanate, (meth) acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, fumaric acid and the like.

In order to copolymerize the monomer mixture to obtain the acrylic copolymer, the monomer mixture may be radically reacted in the presence of a polymerization initiator. As a method of radical reaction of the monomer mixture, that is, a polymerization method, a conventionally known method is used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization and the like.
The said polymerization initiator is not specifically limited, For example, an organic peroxide, an azo compound, etc. are mentioned. Examples of the organic peroxide include 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5 -Dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy Examples include isobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination of two or more.

The acrylic copolymer has a weight average molecular weight (Mw) of 400,000 to 1,000,000. When the weight average molecular weight is less than 400,000, the pressure-sensitive adhesive layer has a reduced cohesive force and an adhesive force at the adherend interface. When the weight average molecular weight exceeds 1,000,000, the pressure-sensitive adhesive layer has a low adhesive force and is easily peeled off when a strong impact is applied. The preferable lower limit of the weight average molecular weight is 500,000, and the preferable upper limit is 700,000.
In order to adjust the weight average molecular weight within the above range, polymerization conditions such as a polymerization initiator and a polymerization temperature may be adjusted.
In addition, a weight average molecular weight (Mw) is a weight average molecular weight of standard polystyrene conversion by GPC (Gel Permeation Chromatography: gel permeation chromatography).

The pressure-sensitive adhesive layer contains 30 to 50 parts by weight of a tackifier resin with respect to 100 parts by weight of the acrylic copolymer.
When the content of the tackifying resin is less than 30 parts by weight, the pressure-sensitive adhesive layer is easily peeled off from the adherend due to peeling stress caused by deformation of the adherend when a strong impact is applied. When the content of the tackifying resin exceeds 50 parts by weight, the pressure-sensitive adhesive layer becomes hard and the adhesive force or tack is lowered, and may be peeled off when a strong impact is applied.

Examples of the tackifying resin include rosin ester resins, hydrogenated rosin resins, terpene resins, terpene phenol resins, coumarone indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, and C9 resins. Examples thereof include petroleum resins and C5-C9 copolymer petroleum resins. These tackifying resins may be used alone or in combination of two or more.

In the pressure-sensitive adhesive layer, a crosslinking structure may be formed between main chains of the resin (the acrylic copolymer and / or the tackifying resin) constituting the pressure-sensitive adhesive layer by adding a crosslinking agent. preferable.
The said crosslinking agent is not specifically limited, For example, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy-type crosslinking agent, a metal chelate type crosslinking agent etc. are mentioned. Of these, isocyanate-based crosslinking agents are preferred. By adding an isocyanate-based crosslinking agent to the pressure-sensitive adhesive layer, the isocyanate group of the isocyanate-based crosslinking agent reacts with the alcoholic hydroxyl group in the resin constituting the pressure-sensitive adhesive layer, thereby cross-linking the pressure-sensitive adhesive layer. It becomes loose. Therefore, the pressure-sensitive adhesive layer can disperse the peeling stress applied intermittently, and has a resistance to peeling from the adherend against the peeling stress caused by the deformation of the adherend when a strong impact is applied. More improved.
The addition amount of the crosslinking agent is preferably 0.01 to 10 parts by weight and more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the acrylic copolymer.

Even if the degree of crosslinking of the pressure-sensitive adhesive layer is too high or too low, the pressure-sensitive adhesive layer may be easily peeled off from the adherend due to the peeling stress caused by the deformation of the adherend. 40 weight% is preferable, 10-40 weight% is more preferable, 15-35 weight% is especially preferable.
The degree of cross-linking of the pressure-sensitive adhesive layer was determined by collecting W1 (g) of the pressure-sensitive adhesive layer, immersing this pressure-sensitive adhesive layer in ethyl acetate at 23 ° C. for 24 hours, and filtering the insoluble matter with a 200-mesh wire mesh. The residue on the wire net is vacuum-dried, and the weight W2 (g) of the dry residue is measured, and calculated by the following formula (2).
Crosslinking degree (% by weight) = 100 × W2 / W1 (2)

Although the thickness of the said adhesive layer is not specifically limited, It is preferable that the thickness (thickness of the adhesive layer of one side) of an adhesive layer is 10-150 micrometers. When the thickness is less than 10 μm, the pressure-sensitive adhesive layer may have reduced impact resistance. When the thickness exceeds 150 μm, the pressure-sensitive adhesive layer may have impaired reworkability or removability.

As for the double-sided adhesive tape for portable electronic devices of this invention, it is preferable that the total thickness of a double-sided adhesive tape is 150-400 micrometers. When the total thickness is less than 150 μm, the impact resistance of the double-sided pressure-sensitive adhesive tape may be lowered. When the total thickness exceeds 400 μm, the double-sided pressure-sensitive adhesive tape may not be suitable for use in bonding and fixing components constituting the portable electronic device to the device body.

As a manufacturing method of the double-sided adhesive tape for portable electronic devices of this invention, the following methods are mentioned, for example.
First, a solution of an adhesive A is prepared by adding a solvent to an acrylic copolymer, a tackifier resin, and a cross-linking agent as necessary, and the solution of the adhesive A is applied to the surface of the substrate. The solvent is completely removed by drying to form the pressure-sensitive adhesive layer A. Next, the release film is superimposed on the pressure-sensitive adhesive layer A so that the release treatment surface faces the pressure-sensitive adhesive layer A.
Next, a release film different from the above release film is prepared, the adhesive B solution is applied to the release treatment surface of the release film, and the solvent in the solution is completely removed by drying, thereby releasing the release film. A laminated film in which the pressure-sensitive adhesive layer B is formed on the surface of the mold film is produced. The obtained laminated film is laminated on the back surface of the base material on which the pressure-sensitive adhesive layer A is formed, with the pressure-sensitive adhesive layer B facing the back surface of the base material to produce a laminate. And by pressing the said laminated body with a rubber roller etc., the double-sided adhesive tape which has an adhesive layer on both surfaces of a base material, and the surface of the adhesive layer was covered with the release film can be obtained.

In addition, two sets of laminated films are produced in the same manner, and a laminated body is produced by superposing these laminated films on both sides of the base material with the adhesive layer of the laminated film facing the base material. By pressing the laminate with a rubber roller or the like, a double-sided pressure-sensitive adhesive tape having an adhesive layer on both surfaces of the base material and having the surface of the adhesive layer covered with a release film may be obtained.

The use of the double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention is not particularly limited, but the use of bonding and fixing components constituting the portable electronic device to the device body is preferable. Specifically, the double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention can be used, for example, as a double-sided pressure-sensitive adhesive tape for bonding and fixing a liquid crystal display panel of a portable electronic device to a device body.
Moreover, the shape of the double-sided pressure-sensitive adhesive tape for portable electronic devices of the present invention in these uses is not particularly limited, and examples thereof include a rectangle, a frame shape, a circle, an ellipse, and a donut shape.

According to the present invention, a portable electronic device that can adhere and fix components constituting a portable electronic device to the device main body, and even if a strong impact is applied, the base material is not destroyed and the separation of the component from the device main body can be suppressed. A double-sided adhesive tape for equipment can be provided.

It is a schematic diagram of the drop impact test of the double-sided adhesive tape obtained by the Example and the comparative example.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

(Preparation of adhesive (1))
In a reactor equipped with a thermometer, a stirrer, and a condenser, 76 parts by weight of butyl acrylate, 21 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, 0.2 parts by weight of 2-hydroxyethyl acrylate, and 80 parts by weight of ethyl acetate After adding nitrogen and replacing with nitrogen, the reactor was heated to start refluxing. Subsequently, 0.1 part by weight of azobisisobutyronitrile was added as a polymerization initiator in the reactor. The solution was refluxed at 70 ° C. for 5 hours to obtain a solution of the acrylic copolymer (a). When the weight average molecular weight of the obtained acrylic copolymer (a) was measured by a GPC method using “2690 Separations Model” manufactured by Water as a column, it was 710,000.
14 parts by weight of polymerized rosin ester, 10 parts by weight of terpene phenol, 10 parts by weight of hydrogenated rosin ester with respect to 100 parts by weight of the solid content of acrylic copolymer (a) contained in the resulting solution of acrylic copolymer (a) Part, 125 parts by weight of ethyl acetate (Fuji Chemical Co., Ltd.), 2.2 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L45” manufactured by Nippon Polyurethane Co., Ltd.), stirred, and pressure-sensitive adhesive (1) Got.

(Preparation of adhesive (2))
Acrylic copolymer (a) except that 58 parts by weight of butyl acrylate, 34 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of ethyl acrylate, 3 parts by weight of acrylic acid, and 0.1 part by weight of 2-hydroxyethyl acrylate were used. Similarly, a solution of an acrylic copolymer (b) having a weight average molecular weight of 680,000 was obtained.
14 parts by weight of polymerized rosin ester, 10 parts by weight of terpene phenol, 10 parts by weight of hydrogenated rosin ester with respect to 100 parts by weight of the solid content of acrylic copolymer (b) contained in the resulting solution of acrylic copolymer (b) Part, 125 parts by weight of ethyl acetate (Fuji Chemical Co., Ltd.), 2.2 parts by weight of an isocyanate-based cross-linking agent (trade name “Coronate L45” manufactured by Nippon Polyurethane Co., Ltd.), stirred, and pressure-sensitive adhesive (2) Got.

(Preparation of adhesive (3))
A weight average was obtained in the same manner as in the acrylic copolymer (a) except that 79 parts by weight of butyl acrylate, 19 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl acrylate were used. A solution of an acrylic copolymer (c) having a molecular weight of 450,000 was obtained.
For 100 parts by weight of the solid content of the (meth) acrylic copolymer (c) contained in the resulting acrylic copolymer (c) solution, 14 weights of polymerized rosin ester, ethyl acetate (produced by Fuji Chemical Co., Ltd.) ) 125 parts by weight, 1.4 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L45” manufactured by Nippon Polyurethane Co., Ltd.) were added and stirred to obtain an adhesive (3).

(Preparation of adhesive (4))
Acrylic copolymer (a) except that 50 parts by weight of butyl acrylate, 32 parts by weight of 2-ethylhexyl acrylate, 15 parts by weight of ethyl acrylate, 3 parts by weight of acrylic acid, and 0.2 parts by weight of 2-hydroxyethyl acrylate were used. Similarly, a solution of an acrylic copolymer (d) having a weight average molecular weight of 1.26 million was obtained.
14 parts by weight of polymerized rosin ester, 10 parts by weight of terpene phenol, 10 parts by weight of hydrogenated rosin ester with respect to 100 parts by weight of the solid content of acrylic copolymer (d) contained in the resulting solution of acrylic copolymer (d). Part, 125 parts by weight of ethyl acetate (Fuji Chemical Co., Ltd.) and 1.2 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L45” manufactured by Nippon Polyurethane Co., Ltd.) Got.

(Preparation of adhesive (5))
60 parts by weight of terpene phenol and 125 parts by weight of ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) with respect to 100 parts by weight of the solid content of the acrylic copolymer (a) contained in the solution of the obtained acrylic copolymer (a) Part of an isocyanate-based crosslinking agent (trade name “Coronate L45” manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred to obtain an adhesive (5).

Example 1
A release paper having a thickness of 150 μm was prepared, the pressure-sensitive adhesive (1) was applied to the release-treated surface of the release paper, and dried at 100 ° C. for 5 minutes, thereby forming a pressure-sensitive adhesive layer having a thickness of 30 μm. This pressure-sensitive adhesive layer was made of a crosslinked metallocene polyethylene foam having a thickness of 140 μm (breaking elongation at 23 ° C. in MD direction: 552%, apparent density: 0.44 g / cm ³ , 25% compression strength in the thickness direction: 208 kPa). Bonded to the surface. Next, in the same manner, the same pressure-sensitive adhesive layer as above was bonded to the opposite surface of the crosslinked metallocene polyethylene foam. This obtained the double-sided adhesive tape covered with the 150-micrometer-thick release paper.

(Examples 2 to 10, Comparative Examples 1 to 13)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the types and thicknesses of the base material and the pressure-sensitive adhesive were changed as described in Tables 2 and 3.

(Evaluation)
The following evaluation was performed about the double-sided adhesive tape obtained by the Example and the comparative example. The evaluation results are shown in Tables 2 and 3.

(1) Drop impact test <Production of test equipment>
In FIG. 1, the schematic diagram of the drop impact test of the double-sided adhesive tape obtained by the Example and the comparative example is shown. The obtained double-sided adhesive tape was punched into an outer diameter of 46 mm, a length of 61 mm, an inner diameter of 44 mm, and a length of 59 mm to produce a frame-shaped test piece having a width of 1 mm. Next, as shown in FIG. 1 (a), the square hole is approximately in the center of the test piece 1 from which the release paper has been peeled off from the polycarbonate plate 3 having a thickness of 38 mm and a square hole having a width of 50 mm and a thickness of 2 mm. After being pasted so that the test piece 1 is positioned, a polycarbonate plate 2 having a width of 55 mm, a length of 65 mm, and a thickness of 1 mm is pasted from the upper surface of the test piece 1 so that the test piece 1 is located substantially in the center, and the test apparatus was assembled. .
Thereafter, a pressure of 5 kgf was applied for 10 seconds from the side of the polycarbonate plate positioned on the upper surface of the test apparatus, and the polycarbonate plate positioned on the upper and lower sides and the test piece were pressed and left at room temperature for 24 hours.

<Drop impact resistance judgment>
As shown in FIG. 1 (b), the produced test apparatus was turned over and fixed to the support base, and an iron ball 4 weighing 300 g passing through the square hole was dropped so as to pass through the square hole. Gradually increase the height at which the iron ball is dropped, measure the height at which the iron ball was dropped when the test piece and the polycarbonate plate were peeled off by the impact applied by dropping the iron ball, The result of “impact test [cm]” was obtained.

In addition, the frame-shaped test piece of width 2mm was produced, and the result of the "drop impact test [cm] at 2 mm width" was obtained by the same method using the obtained test piece.
Furthermore, when the result of the “drop impact test at 1 mm width [cm]” is 60 cm or more and the result of the “drop impact test at 2 mm width [cm]” is 120 cm or more, the drop impact resistance Was determined as ◯, and in the cases other than the above, the drop impact resistance was determined as ×.

According to the present invention, a portable electronic device that can adhere and fix components constituting a portable electronic device to the device main body, and even if a strong impact is applied, the base material is not destroyed and the separation of the component from the device main body can be suppressed. A double-sided adhesive tape for equipment can be provided.

1 Test piece (frame shape)
2 Polycarbonate plate (thickness 1mm)
3 Polycarbonate plate (thickness 2mm)
4 Iron balls (300 g)

Claims (3)

A double-sided pressure-sensitive adhesive tape for portable electronic devices having a pressure-sensitive adhesive layer on both sides of the substrate,
The base material has a breaking elongation at 23 ° C. in the MD direction of 480 to 580%, an apparent density of 0.4 to 0.6 g / cm ³ , and a 25% compressive strength in the thickness direction of 200 to 600 kPa. Consisting of a polyolefin foam,
At least one of the pressure-sensitive adhesive layers comprises 100 parts by weight of an acrylic copolymer having a weight average molecular weight of 400,000 to 1,000,000 obtained by copolymerizing a monomer mixture containing butyl acrylate and 2-ethylhexyl acrylate, and a tackifying resin. A double-sided pressure-sensitive adhesive tape for portable electronic devices, comprising 30 to 50 parts by weight. The thickness of a base material is 120-300 micrometers, The double-sided adhesive tape for portable electronic devices of Claim 1 characterized by the above-mentioned. The double-sided pressure-sensitive adhesive tape for portable electronic devices according to claim 1, wherein the total thickness of the double-sided pressure-sensitive adhesive tape is 150 to 400 μm.

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