JP2016183275A - Adhesive composition and adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition capable of exhibiting a high adhesive strength and a high-temperature holding strength, which can suitably be used in areas for fixing electronic equipment components or fixing vehicle components, and to provide an adhesive tape using the adhesive composition.SOLUTION: An adhesive composition contains a (meth)acrylic acid ester random copolymer having a polar group, a (meth)acrylic tri-block copolymer, and a tackifier resin, and does not contain (meth)acrylic di-block copolymer, in which the (meth)acrylic acid ester random copolymer has a weight average molecular weight (Mw) of 1,000,000 or more, and the content of the (meth)acrylic tri-block copolymer per 100 pts.wt. of the (meth)acrylic acid ester random copolymer having a polar group is 40 to 250 pts.wt..SELECTED DRAWING: None

Description

The present invention is an adhesive composition that can be suitably used for electronic device parts fixing applications and vehicle parts fixing applications, and can exhibit high adhesive strength and high temperature holding power, and an adhesive tape using the adhesive composition. About.

In a portable electronic device (for example, a mobile phone, a portable information terminal, etc.) equipped with an image display device or an input device, a double-sided adhesive tape is used for assembly. Specifically, for example, a double-sided adhesive tape is used to bond a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to bond a touch panel module and a display panel module. It has been. Such a double-sided pressure-sensitive adhesive tape is used, for example, by being punched into a frame shape or the like and arranged around the display screen (for example, Patent Documents 1 and 2). In addition, double-sided adhesive tape is also used for fixing vehicle parts (for example, a vehicle-mounted panel) to a vehicle body.

In applications such as adhesive bonding of parts and adhesive fixation of vehicle parts in recent large portable electronic devices, it is necessary to bond heavy parts or members, and the load on the double-sided adhesive tape is increasing. Also, in recent portable electronic devices, so-called narrower frames, in which the periphery of the display screen is narrowed to ensure a wider screen, are progressing, and the width of the peripheral portion of the screen is extremely narrow in narrowed portable electronic devices. For this reason, there is a demand for high adhesive strength that can reliably fix the member even if the bonding area is small. Further, in the adhesion and fixing of vehicle parts, a high high temperature holding force that does not peel even when exposed to a high temperature in a car in summer is important.
As described above, double-sided pressure-sensitive adhesive tapes used for fixing electronic device parts and in-vehicle parts are required to have higher adhesive force and higher temperature holding force than ever before.

JP 2009-242541 A JP 2009-258274 A

In view of the present situation, the present invention is a pressure-sensitive adhesive composition capable of exhibiting high adhesive strength and high-temperature holding power, which can be suitably used for electronic device component fixing applications and vehicle component fixing applications, and the pressure-sensitive adhesive composition. An object of the present invention is to provide an adhesive tape using the.

The present invention contains a (meth) acrylic ester random copolymer having a polar group, a (meth) acrylic triblock copolymer, and a tackifying resin, and contains a (meth) acrylic diblock copolymer The (meth) acrylic acid ester random copolymer has a weight average molecular weight (Mw) of 1,000,000 or more, and the (meth) acrylic acid ester random copolymer has the polar group. It is an adhesive composition whose content of the said (meth) acrylic triblock copolymer with respect to 100 weight part is 40-250 weight part.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have remarkably improved adhesive strength and holding power by combining a (meth) acrylic ester random copolymer having a polar group with a (meth) acrylic triblock copolymer. As a result, the present invention has been completed. Surprisingly, such an effect of improving the adhesive strength is exhibited only when the (meth) acrylic triblock copolymer is used, and the (meth) acrylic is substituted for the (meth) acrylic triblock copolymer. It has also been found that when a diblock copolymer is used or a (meth) acrylic diblock copolymer is used in combination with a (meth) acrylic triblock copolymer, the desired effect cannot be exhibited. .

The (meth) acrylic acid ester random copolymer having the polar group can be obtained by copolymerizing a (meth) acrylic acid alkyl ester and a monomer mixture containing a polar group-containing monomer.
Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, and the like. These (meth) acrylic acid alkyl esters may be used alone or in combination of two or more.
Examples of the polar group-containing monomer include hydroxyalkyl (meth) acrylate, glycerin dimethacrylate, glycidyl (meth) acrylate, 2-methacryloyloxyethyl isocyanate, (meth) acrylic acid, itaconic acid, maleic anhydride, and croton. An acid, maleic acid, fumaric acid, etc. are mentioned. These polar group-containing monomers may be used alone or in combination of two or more.
Among these, (meth) acrylic acid ester random copolymers having a polar group obtained by copolymerizing a monomer mixture containing butyl (meth) acrylate and (meth) acrylic acid have particularly high adhesive strength and high temperature holding power. It is preferable because

When the monomer mixture contains butyl (meth) acrylate and (meth) acrylic acid, the preferred range of the amount of the (meth) acrylic acid to 100 parts by weight of butyl (meth) acrylate is 1 to 10 parts by weight. is there. Within this range, particularly high adhesive strength and high temperature holding power can be exhibited. The more preferable range of the said compounding quantity is 3-5.

When the monomer mixture contains butyl (meth) acrylate and (meth) acrylic acid, it is preferable to further contain 2-hydroxyethyl (meth) acrylate. Thereby, higher adhesive force and high temperature holding power can be exhibited.
When the monomer mixture contains 2-hydroxyethyl (meth) acrylate, the preferable range of the amount of 2-ethylhexyl (meth) acrylate to 100 parts by weight of butyl (meth) acrylate is 0.01 to 1 part by weight. is there.

In order to obtain a (meth) acrylic acid ester random copolymer having the polar group by copolymerizing the monomer mixture, 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. By adjusting the polymerization conditions such as the polymerization initiator and the polymerization temperature at this time, the weight average molecular weight and the like of the resulting copolymer can be adjusted.

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 (meth) acrylic acid ester random copolymer having a polar group has a weight average molecular weight (Mw) of 1,000,000 or more. By using a (meth) acrylic acid ester random copolymer having a weight average molecular weight (Mw) of 1,000,000 or more, a pressure-sensitive adhesive composition having particularly high adhesive strength can be obtained. The weight average molecular weight (Mw) is preferably 1.2 million or more.
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 (meth) acrylic triblock copolymer has, for example, a structure represented by a general formula ABA. Here, the polymer block represented by A and the polymer block represented by B are both polymer blocks mainly composed of (meth) acrylic acid ester units and have different structures.
Here, the difference in structure means that the polymer block represented by A and the polymer block represented by B have different types of monomer units constituting each polymer block, or the monomer unit composition is different. It means that the structures of the polymer block represented by A and the polymer block represented by B are different from each other due to different or different stereoregularity.

In the (meth) acrylic triblock copolymer, it is preferable that A is a methacrylic acid ester polymer block and B is an acrylic acid ester polymer block. By combining the acrylic triblock copolymer having such a structure with the (meth) acrylic acid ester random copolymer having the polar group, the resulting pressure-sensitive adhesive composition has particularly high adhesive strength and high-temperature holding power. Can be demonstrated.
Hereinafter, the (meth) acrylic triblock copolymer in which A is a methacrylic acid ester polymer block and B is an acrylic acid ester polymer block will be described in more detail.

Examples of the methacrylic acid ester monomer constituting the methacrylic acid ester polymer block include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, and methacrylic acid t. -Butyl, 2-ethylhexyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, 2-cyanoethyl methacrylate, phenyl methacrylate and the like. These methacrylic acid ester monomers may be used alone or in combination of two or more.

Examples of the acrylate monomer constituting the acrylate polymer block include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and acrylic acid sec. -Butyl, n-tetradecyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate and the like. These acrylate monomers may be used alone or in combination of two or more.

The methacrylic acid ester polymer block and the acrylic acid ester polymer block may be an acrylic acid ester monomer or a methacrylic acid ester monomer, or ethyl, propylene, etc. Other constituents (structural units) such as olefins, lactones such as ε-caprolactone and parerolactone may be contained.

The ratio of A (methacrylic ester polymer block) to B (acrylic ester polymer block) in the (meth) acrylic triblock copolymer is not particularly limited, but is 5:95 to 80:20 by weight. Preferably there is. By setting the ratio in this range, high adhesive force can be exhibited without reducing the cohesive force of the adhesive composition.

The said (meth) acrylic triblock copolymer has a preferable minimum of 50,000 and a preferable upper limit of 300,000 of a weight average molecular weight (Mw). By setting the weight average molecular weight (Mw) within this range, the cohesive force of the pressure-sensitive adhesive composition is not lowered, and higher adhesive force can be exhibited. The minimum with a more preferable weight average molecular weight (Mw) is 60,000, and a more preferable upper limit is 200,000.
The (meth) acrylic triblock copolymer has a preferred lower limit of 1.1 and a preferred upper limit of 2.8 for the molecular weight distribution (Mw / Mn). By setting the molecular weight distribution molecular weight distribution (Mw / Mn) within this range, the cohesive force of the pressure-sensitive adhesive composition is not lowered, and higher adhesive force can be exhibited.
The molecular weight distribution (Mw / Mn) is a ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn). A weight average molecular weight (Mw) and a number average molecular weight (Mn) are measured as polystyrene conversion molecular weight by GPC (Gel Permeation Chromatography).

As a commercial item of the said (meth) acrylic triblock copolymer, Clarity La2330, La2140e, La2250, La4825 (all are the Kuraray company make) etc. are mentioned, for example.

The pressure-sensitive adhesive composition of the present invention does not contain a (meth) acrylic diblock copolymer. The (meth) acrylic diblock copolymer is used instead of the (meth) acrylic triblock copolymer, or the (meth) acrylic diblock copolymer is added to the (meth) acrylic triblock copolymer. If used together, the expected performance cannot be demonstrated. Although the reason for this is unclear, it is thought that the diblock copolymer is unlikely to have a sea-island structure like the triblock copolymer and the cohesive force is lowered.
The (meth) acrylic diblock copolymer has a structure represented by, for example, the general formula AB, and A, B, etc. constituting the copolymer are the above (meth) acrylic triblock copolymers. The same as in the case of the polymer.

In the pressure-sensitive adhesive composition of the present invention, the lower limit of the content of the (meth) acrylic triblock copolymer with respect to 100 parts by weight of the (meth) acrylic acid ester random copolymer having the polar group is 40 parts by weight, and the upper limit is 250 parts by weight. By setting the content of the (meth) acrylic triblock copolymer within this range, high adhesive force and high temperature holding power can be exhibited. The preferable lower limit of the content of the (meth) acrylic triblock copolymer is 50 parts by weight, the preferable upper limit is 200 parts by weight, the more preferable lower limit is 80 parts by weight, and the more preferable upper limit is 125 parts by weight.

Examples of the tackifier resins include rosin ester resins, hydrogenated rosin resins, terpene resins, terpene phenol resins, coumarone indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, C9. Based petroleum resin, C5-C9 copolymerized petroleum resin and the like. These tackifying resins may be used alone or in combination of two or more. Among these, at least one selected from the group consisting of terpene phenol resins and rosin resins is preferable.

Although content of the said tackifying resin is not specifically limited, The preferable minimum with respect to 100 weight part of (meth) acrylic acid ester random copolymers which have the said polar group is 10 weight part, and a preferable upper limit is 60 weight part. When the content of the tackifying resin is less than 10 parts by weight, the adhesive strength of the pressure-sensitive adhesive composition may be reduced. When content of the said tackifying resin exceeds 60 weight part, the said adhesive composition may become hard and adhesive force or tack may fall. The minimum with more preferable content of the said tackifying resin is 15 weight part, and a more preferable upper limit is 30 weight part.

The pressure-sensitive adhesive composition of the present invention may further contain a crosslinking agent. By containing a crosslinking agent, the gel fraction can be adjusted when the pressure-sensitive adhesive composition of the present invention is used to form a pressure-sensitive adhesive layer of a pressure-sensitive adhesive tape.
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.
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 (meth) acrylic acid ester random copolymer having the polar group.

The pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition of the present invention is also one aspect of the present invention.
The pressure-sensitive adhesive tape may be a non-support tape having no base material, may be a single-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one side of the base material, and has a pressure-sensitive adhesive layer on both sides of the base material. A double-sided adhesive tape may be used.

The substrate is not particularly limited. For example, a base having a single layer or a multilayer structure containing at least one selected from the group consisting of a polyester film, a polyolefin foam, a rubber elastomer, an acrylic elastomer, and a urethane elastomer. A material is preferred.

The pressure-sensitive adhesive layer has a preferred lower limit of the gel fraction of 15% by weight and a preferred upper limit of 60% by weight. If the gel fraction is less than 15% by weight, the pressure-sensitive adhesive layer may become too soft, and the adhesive force and high-temperature holding power may decrease. When the gel fraction exceeds 60% by weight, the cross-linking density of the pressure-sensitive adhesive layer becomes too high, and the pressure-sensitive adhesive tape may be easily peeled off. A more preferable lower limit of the gel fraction is 20% by weight, and a more preferable upper limit is 50% by weight.
The gel fraction is measured as follows. First, the adhesive tape was cut into a flat rectangular shape of 50 mm × 100 mm to prepare a test piece. After the test piece was immersed in ethyl acetate at 23 ° C. for 24 hours, the test piece was taken out from ethyl acetate and subjected to a condition of 110 ° C. For 1 hour. The weight of the test piece after drying is measured, and the gel fraction is calculated using the following formula (1). In addition, the release film for protecting an adhesive layer shall not be laminated | stacked on the test piece.
Gel fraction (% by weight) = 100 × (W2-W0) / (W1-W0) (1)
(W0: weight of substrate, W1: weight of test piece before immersion, W2: weight of test piece after immersion and drying)

Although the thickness of the said adhesive layer is not specifically limited, A preferable minimum is 10 micrometers and a preferable upper limit is 100 micrometers. When the thickness of the pressure-sensitive adhesive layer is less than 10 μm, the pressure-sensitive adhesive strength and high-temperature holding power of the pressure-sensitive adhesive tape may be reduced. When the thickness of the pressure-sensitive adhesive layer exceeds 100 μm, the reworkability or removability of the pressure-sensitive adhesive tape may be impaired.

In the pressure-sensitive adhesive tape of the present invention, the preferable lower limit of the total thickness of the pressure-sensitive adhesive tape (the total thickness of the base material and the pressure-sensitive adhesive layer) is 100 μm, and the preferable upper limit is 2000 μm. When the total thickness of the pressure-sensitive adhesive tape is less than 100 μm, the pressure-sensitive adhesive strength and high-temperature holding power of the pressure-sensitive adhesive tape may be reduced. When the total thickness of the pressure-sensitive adhesive tape exceeds 2000 μm, it may not be suitable for applications such as adhesive fixing of parts constituting mobile electronic devices and adhesive fixing of in-vehicle parts. The more preferable lower limit of the total thickness of the pressure-sensitive adhesive tape is 150 μm, and the more preferable upper limit is 1500 μm.

As a manufacturing method of the adhesive tape of this invention, when an adhesive tape is a double-sided adhesive tape, the following methods are mentioned, for example.
First, a (meth) acrylic acid ester random copolymer having the above polar group, a (meth) acrylic triblock copolymer, a tackifier resin, and a crosslinking agent, if necessary, a solvent is added to the adhesive A solution. Then, the pressure-sensitive adhesive A solution is applied to the surface of the substrate, and the solvent in the solution is completely removed by drying to form the acrylic pressure-sensitive adhesive layer A. Next, a release film is overlaid on the formed acrylic pressure-sensitive adhesive layer A so that the release treatment surface faces the acrylic 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 acrylic pressure-sensitive adhesive layer B is formed on the surface of the mold film is produced. The obtained laminated film is superposed on the back surface of the base material on which the acrylic pressure-sensitive adhesive layer A is formed, with the acrylic pressure-sensitive adhesive layer B facing the back surface of the base material to produce a laminate. Then, by pressing the laminate with a rubber roller or the like, a double-sided pressure-sensitive adhesive tape having an acrylic pressure-sensitive adhesive layer on both surfaces of the base material and having the surface of the acrylic pressure-sensitive adhesive layer covered with a release film can be obtained. it can.

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 acrylic adhesive layer of the laminated film facing the base material. Then, by pressing this laminate with a rubber roller or the like, a double-sided pressure-sensitive adhesive tape having an acrylic pressure-sensitive adhesive layer on both surfaces of the base material and the surface of the acrylic pressure-sensitive adhesive layer covered with a release film can be obtained. Good.

Although the use of the adhesive tape of this invention is not specifically limited, It can use especially suitably for fixation of electronic equipment components, and fixation of vehicle-mounted components. Specifically, the pressure-sensitive adhesive tape of the present invention can be used for adhesive fixing of electronic device parts in large-sized portable electronic devices, adhesive fixing of in-vehicle components (for example, in-vehicle panels), and the like.
The shape of the pressure-sensitive adhesive tape of the present invention in these applications is not particularly limited, and examples thereof include a rectangle, a frame shape, a circle, an ellipse, and a donut shape.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can be used suitably for an electronic device component fixation use or a vehicle component fixation use, and can exhibit high adhesive force and high temperature holding power, and this adhesive composition were used. An adhesive tape can be provided.

It is a schematic diagram explaining the evaluation method of PUSH adhesive strength of an adhesive tape. It is a schematic diagram explaining the evaluation method of the high temperature holding power of an adhesive tape.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Preparation of (meth) acrylic acid ester random copolymer (A))
To a reactor equipped with a thermometer, a stirrer, and a condenser tube, 100 parts by weight of butyl acrylate, 3 parts by weight of acrylic acid, 0.1 part by weight of 2-hydroxyethyl acrylate and 80 parts by weight of ethyl acetate were added, and the reaction was carried out with nitrogen. The vessel was heated to begin refluxing. Subsequently, 0.15 parts by weight of azoisobutyronitrile (AIBN) was added as a polymerization initiator in the reactor. The solution was refluxed at 70 ° C. for 5 hours to obtain a solution of a (meth) acrylic acid ester random copolymer (A). When the weight average molecular weight of the obtained (meth) acrylic acid ester random copolymer (A) was measured by a GPC method using “2690 Separations Model” manufactured by Water as a column, it was 1,200,000.

(Preparation of (meth) acrylic acid ester random copolymer (B))
A (meth) acrylate random copolymer (B) is obtained in the same manner as in the case of the (meth) acrylate random copolymer (A) except that the amount of AIBN added is 0.1 parts by weight. It was. When the weight average molecular weight of the obtained (meth) acrylic acid ester random copolymer (B) was measured by a GPC method using “2690 Separations Model” manufactured by Water as a column, it was 1.24 million.

(Preparation of (meth) acrylic acid ester random copolymer (C))
After adding 100 parts by weight of butyl acrylate and 80 parts by weight of ethyl acetate to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and replacing with nitrogen, the reactor was heated to start refluxing. Subsequently, 10 parts by weight of AIBN was added as a polymerization initiator in the reactor. The solution was refluxed at 100 ° C. for 5 hours to obtain a solution of a (meth) acrylic acid ester random copolymer (C). With respect to the obtained (meth) acrylic acid ester random copolymer (C), the weight average molecular weight was measured by a GPC method using “2690 Separations Model” manufactured by Water Co. as a column, which was 50,000.

(Preparation of (meth) acrylic acid ester random copolymer (D))
A (meth) acrylate random copolymer (D) was obtained in the same manner as in the case of the (meth) acrylate random copolymer (C) except that only 100 parts by weight of butyl acrylate was used as the monomer. . With respect to the obtained (meth) acrylic acid ester random copolymer (D), the weight average molecular weight was measured by GPC method using “2690 Separations Model” manufactured by Water Co. as a column.

(Preparation of (meth) acrylic acid ester random copolymer (E))
A (meth) acrylate random copolymer (E) is obtained in the same manner as in the case of the (meth) acrylate random copolymer (A) except that the amount of AIBN added is 0.3 parts by weight. It was. When the weight average molecular weight of the obtained (meth) acrylic acid ester random copolymer (E) was measured by a GPC method using “2690 Separations Model” manufactured by Water as a column, it was 850,000.

Example 1
The (meth) acrylic triblock is based on 100 parts by weight of the solid content of the (meth) acrylic acid ester random copolymer (A) contained in the solution of the obtained (meth) acrylic acid ester random copolymer (A). 250 parts by weight of “La2330” manufactured by Kuraray as a copolymer, 20 parts by weight of a polymerized rosin ester having a softening point of 135 ° C. as a tackifier, and 1.5 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L45” manufactured by Nippon Polyurethane) Part was added and stirred to obtain an adhesive composition.

A release paper was prepared, the pressure-sensitive adhesive composition was applied to the release-treated surface of this release paper, and dried at 100 ° C. for 5 minutes to form a pressure-sensitive adhesive layer having a thickness of 50 μm. This pressure-sensitive adhesive layer was bonded to the surface of a 150 μm thick substrate made of a polyethylene foam substrate (foaming ratio 1.8 times). Next, in the same manner, the same pressure-sensitive adhesive layer as above was bonded to the opposite surface of the substrate. This obtained the double-sided adhesive tape covered with the release paper.
About the adhesive layer of the obtained double-sided adhesive tape, when the gel fraction was measured, it was 17%.

(Examples 2-12, Comparative Examples 1-14)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the (meth) acrylic acid ester random copolymer and the like were changed to those shown in Tables 1 to 4.

<Evaluation>
The following evaluation was performed about the double-sided adhesive tape obtained by the Example and the comparative example. The results are shown in Tables 1-4.

(1) Evaluation of PUSH adhesive strength FIG. 1 is a schematic diagram illustrating an evaluation method of PUSH adhesive strength of a double-sided adhesive tape. 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.

As shown in FIG. 1 (b), the prepared test apparatus is turned over and fixed to a support base, and a load 4 is slowly applied through a square hole at a speed of 10 mm / min, and the test piece and the polycarbonate plate are peeled off by the load. The load value was measured.
Based on the measured values obtained, PUSH adhesive strength was determined according to the following criteria.
○: Load at peeling is 75N or more ×: Load at peeling is less than 75N

(2) Evaluation of high temperature holding power FIG. 2 is a schematic diagram for explaining an evaluation method of the high temperature holding power of the double-sided pressure-sensitive adhesive tape. The obtained double-sided pressure-sensitive adhesive tape was punched into a strip shape having a width of 25 mm to produce a test piece 5. Next, as shown in FIG. 2, the test piece 5 from which the release paper on one surface was peeled was attached to a polycarbonate plate 6 having a thickness of 2 mm. The affixing was performed by reciprocating the 2 kg roller once at a speed of 300 mm / min under a condition of 23 ° C. At this time, the adhesion area was set to 25 mm × 25 mm so that one end of the test piece 5 protruded from the polycarbonate plate 6. Next, a 1 kg weight 7 was attached to one end of the test piece, hung and left at 85 ° C. for 24 hours, and then the deviation of the adhesive tape was visually observed to determine the high temperature holding force according to the following criteria.
○: No deviation was found on the adhesive tape ×: The adhesive tape dropped

ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can be used suitably for an electronic device component fixation use or a vehicle component fixation use, and can exhibit high adhesive force and high temperature holding power, and this adhesive composition were used. An adhesive tape can be provided.

1 Double-sided adhesive tape test piece (frame shape)
2 Polycarbonate plate 3 Polycarbonate plate 4 Load 5 Double-sided adhesive tape test piece 6 Polycarbonate plate 7 Weight

Claims (9)

A pressure-sensitive adhesive composition containing a (meth) acrylic acid ester random copolymer having a polar group, a (meth) acrylic triblock copolymer, and a tackifying resin, and not containing a (meth) acrylic diblock copolymer A thing,
The (meth) acrylic acid ester random copolymer has a weight average molecular weight (Mw) of 1 million or more,
Content of the said (meth) acrylic triblock copolymer with respect to 100 weight part of (meth) acrylic acid ester random copolymers which have the said polar group is 40-250 weight part, The adhesive composition characterized by the above-mentioned. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth) acrylic triblock copolymer is such that A is a methacrylic acid ester polymer block and B is an acrylic acid ester polymer block. The (meth) acrylic triblock copolymer has a weight average molecular weight (Mw) of 50,000 to 300,000 and a molecular weight distribution (Mw / Mn) of 1.1 to 2.8. The pressure-sensitive adhesive composition according to 1. The pressure-sensitive adhesive composition according to claim 1, 2 or 3, wherein the tackifying resin is at least one selected from the group consisting of a terpene phenol resin and a rosin resin. An adhesive tape comprising an adhesive layer comprising the adhesive composition according to claim 1, 2, 3 or 4. 6. A base material having a single layer or a multilayer structure containing at least one selected from the group consisting of a polyester film, a polyolefin foam, a rubber elastomer, an acrylic elastomer and a urethane elastomer. Adhesive tape. The pressure-sensitive adhesive tape according to claim 5 or 6, wherein the pressure-sensitive adhesive layer has a thickness of 10 to 100 µm. The pressure-sensitive adhesive tape according to claim 5, 6 or 7, wherein the pressure-sensitive adhesive tape is used for fixing electronic device parts. 8. The pressure-sensitive adhesive tape according to claim 5, 6 or 7, wherein the pressure-sensitive adhesive tape is used for fixing vehicle parts.

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