Temperature-sensitive adhesive

Abstract

To provide a temperature-sensitive adhesive that develops adhesion force at a temperature of normal temperature to below normal temperature and decreases the adhesive force by lowering the temperature more than the temperature where the adhesive force was developed.MEANS FOR SOLVING THE PROBLEM: A temperature-sensitive adhesive composition containing a 4-methyl-1-pentene and α-olefin copolymer as an elastomer component, where an adhesive sheet provided with an adhesive layer made of the temperature-sensitive adhesive composition on at least one surface of a substrate has a lower limit adhesion force developing temperature Tlow capable of maintaining a level where adhesive strength against BA-SUS plate is 0.15 N / 10 mm or more within the temperature range of 10°C to 25°C, and in a temperature lower by 5°C than the lower limit adhesive strength developing temperature Tlow (Tlow-5°C), the adhesive strength against the BA-SUS plate shows adhesive behavior with an adhesion strength of 0.12 N / 10 mm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a heat-sensitive adhesive composition and an adhesive sheet having an adhesive layer formed from the composition, and in particular to a heat-sensitive adhesive composition and an adhesive sheet which exhibit adhesive strength at temperatures equal to or lower than room temperature (25°C). [Background technology]

[0002] 2. Description of the Related Art Thermosensitive adhesives, the adhesive strength of which can be controlled by heat, and adhesive sheets using such adhesives in their adhesive layers are known. For example, a thermosensitive adhesive has been proposed that contains a side-chain crystalline polymer and exhibits adhesive strength at a temperature equal to or higher than the melting point of the side-chain crystalline polymer. When the thermosensitive adhesive is cooled to a temperature below the melting point, the side-chain crystalline polymer crystallizes, causing a decrease in adhesive strength (Patent Documents 1, 2, etc.). Furthermore, as a thermosensitive adhesive that can firmly adhere to polyimide-based adherends at room temperature and whose adhesive strength decreases at temperatures above the melting point of the thermosensitive resin, allowing easy peeling, a thermosensitive adhesive has been proposed that contains a base resin and a non-carboxyl group-containing side chain crystalline polymer, and whose adhesive strength to polyimide-based adherends decreases at temperatures above the melting point of the non-carboxyl group-containing side chain crystalline polymer (Patent Document 3). Furthermore, a heat-sensitive adhesive sheet has been proposed, which has an adhesive layer formed from an adhesive composition containing a (meth)acrylic acid ester polymer (A), a crosslinking agent (B), and a polyrotaxane compound (C), and which has an adhesive strength to glass of less than 1.5 N / 25 mm at 20°C and an adhesive strength to glass of 2.0 N / 25 mm or more at 80°C (Patent Document 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-251923 [Patent Document 2] JP 2010-202809 A [Patent Document 3] JP 2019143065 A [Patent Document 4] Patent No. 7017442 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a temperature-sensitive adhesive that exhibits adhesive strength at room temperature or below, and that reduces its adhesive strength when cooled to a temperature lower than the temperature at which it exhibits its adhesive strength. [Means for solving the problem]

[0005] That is, the present invention relates to the following heat-sensitive adhesive composition and adhesive sheet. [1] A heat-sensitive adhesive composition containing a 4-methyl-1-pentene / α-olefin copolymer as an elastomer component, The adhesive sheet having an adhesive layer made of the heat-sensitive adhesive composition on at least one surface of a substrate has a lower limit of adhesive strength development temperature T at which the adhesive strength against a BA-SUS plate can be maintained at a level of 0.15 N / 10 mm or more within a temperature range of 10° C. to 25° C. low and the lower limit of the adhesive strength development temperature T low 5°C lower than the temperature (T low At -5°C, the adhesive strength against BA-SUS plate is 0.12N / 10mm or less. Adhesive composition. [2] The 4-methyl-1-pentene / α-olefin copolymer is The pressure-sensitive adhesive composition according to [1], which is a copolymer containing 70 mol % to 90 mol % of a unit structure derived from 4-methyl-1-pentene, 10 mol % to 30 mol % of a unit structure derived from an α-olefin having 2 or 3 carbon atoms, and further containing 0 to 10 mol % of other unit structures (with the total of all unit structures being 100 mol %). [3] The pressure-sensitive adhesive composition according to [1], further comprising a tackifier resin and a softener. [4] The pressure-sensitive adhesive composition according to [2], wherein the tackifier resin is at least one selected from the group consisting of aliphatic hydrocarbon resins, aromatic modified terpene resins, and alicyclic hydrogenated petroleum resins. [5] The pressure-sensitive adhesive composition according to [3], wherein the softener is at least one selected from the group consisting of oils, waxes, and polybutene. [6] A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [5] on at least one surface of the substrate. Effect of the Invention

[0006] The thermosensitive adhesive composition of the present invention can provide a thermosensitive adhesive composition and an adhesive sheet which exhibit adhesive strength at room temperature or lower and can be attached to an adherend, and which exhibits reduced adhesive strength at a temperature slightly lower than the temperature at which the adhesive strength is exhibited and can be easily peeled off from the adherend. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [Thermosensitive adhesive composition] The heat-sensitive adhesive composition according to the present invention contains a polyolefin elastomer, specifically, a 4-methyl-1-pentene·α-olefin copolymer.

[0008] The 4-methyl-1-pentene-α-olefin copolymer may contain, for example, 70 mol % to 90 mol % of unit structures derived from 4-methyl-1-pentene and 10 mol % to 30 mol % of unit structures derived from an α-olefin having 2 or 3 carbon atoms. The copolymer may further contain 10 mol % or less of unit structures derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene (the total of all unit structures is 100 mol %).

[0009] The proportion of unit structures derived from 4-methyl-1-pentene in the 4-methyl-1-pentene·α-olefin copolymer can be, for example, 72 mol % to 89 mol %, or 72 mol % to 85 mol %. The proportion of unit structures derived from an α-olefin having 2 or 3 carbon atoms in the 4-methyl-1-pentene·α-olefin copolymer can be, for example, 11 mol % to 28 mol %, or 15 mol % to 28 mol %.

[0010] Examples of the α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene include linear or branched α-olefins, cyclic olefins, aromatic vinyl compounds, conjugated dienes, non-conjugated polyenes, functional vinyl compounds, etc. Examples of the functionalized vinyl compounds include hydroxyl group-containing olefins, halogenated olefins, unsaturated carboxylic acids, unsaturated amines, unsaturated acid anhydrides, halides of the unsaturated carboxylic acids, and unsaturated epoxy compounds. Among these, the α-olefins having 4 to 20 carbon atoms include 1-butene, 1 At least one selected from the group consisting of 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, vinylcyclohexane, and styrene. When the 4-methyl-1-pentene / α-olefin copolymer contains a unit structure derived from the α-olefin having 4 to 20 carbon atoms, the copolymer may contain only one type of unit structure derived from the α-olefin having 4 to 20 carbon atoms, or may contain two or more types of unit structures derived from the α-olefin having 4 to 20 carbon atoms. The proportion of the unit structure derived from the α-olefin having 4 to 20 carbon atoms in the 4-methyl-1-pentene / α-olefin copolymer is, for example, 5 mol % or less, 3 mol % or less, or can be 1 mol % or less, and the copolymer can be an embodiment that does not contain such unit structure.

[0011] The 4-methyl-1-pentene·α-olefin copolymer may be a commercially available product, and for example, Absoutomer (registered trademark) EP-1001, EP-1013, etc. manufactured by Mitsui Chemicals, Inc. may be preferably used.

[0012] The heat-sensitive adhesive composition according to the present invention may further contain a tackifier resin. Examples of tackifying resins include rosin resins such as gum rosin, tall rosin, wood rosin, disproportionated rosin, and polymerized rosin; rosin ester resins such as glycerin esters and pentaerythritol esters of these rosins; and hydrogenated products thereof; terpene resins such as terpene resins, hydrocarbon-modified terpene resins, aromatic-modified terpene resins, and hydrogenated products thereof; terpene phenolic resins such as terpene phenolic resins and hydrogenated products of terpene phenolic resins; petroleum resins (hydrocarbon resins) such as aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, dicyclopentadiene petroleum resins, pure monomer petroleum resins, and hydrogenated products thereof; and styrene-based resins, coumarone-indene-based resins, alkylphenol-based resins, xylene-based resins, dammar, copal, and shellac. In the present invention, from the viewpoint of compatibility with the above-mentioned 4-methyl-1-pentene·α-olefin copolymer, for example, aliphatic hydrocarbon resins, aromatic modified terpene resins, alicyclic hydrogenated petroleum resins, etc. Also, tackifier resins other than these may be blended as long as they do not impair the effects of the present invention.

[0013] As the tackifier resin, a commercially available product can be used. Commercially available products of the aliphatic hydrocarbon resin include Quinton (registered trademark) A100, B170, K100, M100, R100, and C200S manufactured by Zeon Corporation. Commercially available products of the aromatic modified terpene resin include the YS Resin TO series manufactured by Yasuhara Chemical Co., Ltd. Examples of commercially available alicyclic hydrogenated petroleum resins include Arcon (registered trademark) P-90 and P-100 manufactured by Arakawa Chemical Industries, Ltd. These tackifier resins can be used alone or in combination of two or more kinds. The tackifier resin can be blended in an amount of, for example, 30 to 200 parts by mass, or 30 to 150 parts by mass, relative to 100 parts by mass of the 4-methyl-1-pentene·α-olefin copolymer.

[0014] The pressure-sensitive adhesive composition according to the present invention may further contain a softener, if necessary. The softener has the function of adjusting the adhesive properties at low temperatures, and examples of the softener include oils such as paraffin oil and naphthene oil; waxes such as paraffin wax; and liquid polybutene (low molecular weight polybutene) having an average molecular weight of about 200 to 5000. The softening agent can be mixed in an amount of, for example, 20 to 80 parts by mass with respect to 100 parts by mass of the 4-methyl-1-pentene·α-olefin copolymer.

[0015] In addition to the above-mentioned components, the pressure-sensitive adhesive composition according to the present invention may appropriately contain other components such as a plasticizer, an inorganic filler such as calcium carbonate or silica, an antioxidant, a vulcanization accelerator, a thickener, a surfactant, a preservative, an antifoaming agent, and a dispersant.

[0016] <Adhesive behavior> The heat-sensitive adhesive composition of the present invention is characterized in that it exhibits specific adhesive behavior in an adhesive sheet having an adhesive layer made of the composition provided on at least one surface of a substrate. That is, the pressure-sensitive adhesive sheet has a lower limit adhesive strength development temperature T at which the adhesive strength against the BA-SUS plate can be maintained at a level of 0.15 N / 10 mm or more within the temperature range of 10° C. to 25° C. low and the lower limit of the adhesive strength development temperature T low 5°C lower than the temperature (T low At -5°C, the adhesive strength against BA-SUS plate is 0.12 N / 10 mm or less. By exhibiting such adhesive behavior, the thermosensitive adhesive composition according to the present invention is useful, for example, for use as a process film in semiconductor manufacturing processes. The adherend to which the adhesive sheet used as such a process film is directed has a very smooth mirror surface and is very low in impurities such as dust. Furthermore, the pressure-bonding process of the adhesive tape to the adherend is also in a usage environment in which a uniform, even, and sufficient load is stably applied, so that the adhesive strength that can be said to be functionally sufficient is easily expressed at a lower pressure than in the usage environment of a general adhesive tape, that is, even if the adhesive strength is lower than the general adhesive strength, it can function sufficiently. Thus, the thermosensitive adhesive composition according to the present invention is a pressure-sensitive adhesive composition that is applied to an adherend at a temperature of about 25°C to a room temperature or lower, and is applied to an adherend by expressing sufficient adhesive strength (0.15N / 10mm or more) to a very smooth surface, and can be easily peeled off from the adherend by, if necessary, lowering the temperature of the application surface slightly below the temperature at which the adhesive strength is expressed. In addition, in the above adhesive behavior, the lower limit of the adhesive strength is 0.15 N / 10 mm or more, for example, 0.20 N / 10 mm, and the adhesive strength development temperature T low 5°C lower than the temperature (T low The adhesive strength at -5°C is 0.12 N / 10 mm or less, for example 0.10 N / 10 mm or less.

[0017] [Adhesive sheet] The present invention also relates to a pressure-sensitive adhesive sheet having a substrate and a pressure-sensitive adhesive layer formed from the above-mentioned temperature-sensitive pressure-sensitive adhesive composition on at least one surface of the substrate. The adhesive sheet is not particularly limited in its application or use, and can be used in a variety of applications, such as an industrial process film, a pressure-sensitive adhesive sheet or tape, a general-purpose pressure-sensitive adhesive sheet or tape, or a patch for application to human skin, etc.

[0018] Examples of the substrate (also referred to as support) include films, sheets, nonwoven fabrics, Japanese paper, cotton fabrics, knitted fabrics, woven fabrics, laminated composites of nonwoven fabrics and films, etc. These substrates can be appropriately selected depending on the application of the pressure-sensitive adhesive sheet. Examples of materials for these substrates include natural materials such as cotton, silk, hemp, and paper; polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyamides, polyimides, polyurethanes, polycarbonates, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-polypropylene copolymers, and synthetic resins such as polyvinyl chloride. The substrate may have either a single-layer structure or a multi-layer structure, and the thickness of the substrate is, for example, 5 to 500 μm. In order to enhance adhesion to the pressure-sensitive adhesive layer, the surface of the substrate on which the pressure-sensitive adhesive layer is to be formed may be subjected to a surface treatment, such as a corona treatment, a plasma treatment, a blast treatment, a chemical etching treatment, or a primer treatment.

[0019] The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet according to the present invention can be formed by, for example, coating the pressure-sensitive adhesive composition on at least one surface of the above-mentioned substrate. The method for forming the adhesive layer is not particularly limited, and any conventionally known method can be used, such as the solvent method (dissolving in an organic solvent and coating), which is a common method for producing adhesive sheets, patches, etc., the ointment coating method (a method in which heating is minimized during the mixing and drying steps), the emulsion method (dissolving in an aqueous solvent and coating), the hot melt method, the calendar method, etc. For example, the pressure-sensitive adhesive layer can be formed by supplying a pressure-sensitive adhesive composition to the upper surface of the substrate (support) or one of the upper surfaces of a release liner described later by a coating method, an extrusion molding method, etc. Alternatively, the pressure-sensitive adhesive layer can be produced by supplying a pressure-sensitive adhesive between the substrate and a release liner described later, or by co-extrusion molding the substrate and the pressure-sensitive adhesive layer.

[0020] For example, examples of a coating means for coating the above-mentioned pressure-sensitive adhesive composition on the above-mentioned substrate include an applicator, a coater, etc. Examples of the coater include a knife coater, a roll coater, a calendar coater, a comma coater, a gravure coater, and a rod coater.

[0021] The thickness of the pressure-sensitive adhesive layer can be, for example, from 5 to 60 μm, alternatively from 10 to 60 μm, or alternatively from 10 to 50 μm.

[0022] In addition, when the pressure-sensitive adhesive layer is laminated on both sides of the substrate, the pressure-sensitive adhesive layer on the other side is not particularly limited as long as the pressure-sensitive adhesive layer on one side is made of the above-mentioned pressure-sensitive adhesive composition. When the pressure-sensitive adhesive layer on the other side is composed of, for example, the above-mentioned pressure-sensitive adhesive composition, its composition may be the same as or different from the composition of the pressure-sensitive adhesive layer on one side. The adhesive layer on the other side may be made of, for example, a pressure-sensitive adhesive such as a natural rubber adhesive, a synthetic rubber adhesive, a styrene / butadiene latex-based adhesive, or an acrylic adhesive. When the pressure-sensitive adhesive layer is laminated on both sides of the substrate, the thickness of the pressure-sensitive adhesive layer on one side may be the same as or different from the thickness of the pressure-sensitive adhesive layer on the other side.

[0023] In the pressure-sensitive adhesive sheet according to the present invention, a release film (also called a separator, release liner, etc.) may be laminated on the pressure-sensitive adhesive layer. The release film may be one commonly used in the technical fields of adhesive sheets, patches, etc., and may be, for example, a film made of polyethylene terephthalate or the like, coated with a release agent having release properties, such as silicone resin or fluororesin. The thickness of the release film is preferably 5 to 500 μm, more preferably 25 to 250 μm. The release film may be peeled off when the adhesive sheet is used. EXAMPLES

[0024] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0025] <Preparation of Pressure-Sensitive Adhesive Composition and Fabrication of Pressure-Sensitive Adhesive Sheet> The components were mixed according to the formulations shown in Tables 2 to 4 to prepare heat-sensitive adhesive compositions of Examples 1 to 26. The pressure-sensitive adhesive layer-forming compositions of Examples 1 to 26 were applied in a coating amount per unit area of ​​15 to 40 g / m 2 The adhesive composition was applied to a support (see Tables 1 and 2 to 4) (corona-treated surface (PET) or primer layer (NK350-PET)) so that the adhesive layer had a thickness of 15 to 40 μm, forming a pressure-sensitive adhesive layer (thickness 15 to 40 μm). The blending ratios of the pressure-sensitive adhesive compositions shown in Tables 2 to 4 are solids ratios obtained by removing the solvent (here, toluene) from the pressure-sensitive adhesive liquid. Furthermore, a release film (silicone-treated polyethylene terephthalate, thickness 25 μm) was laminated as a separator on the exposed surface of the formed adhesive layer to obtain a laminate in which the substrate, adhesive layer, and separator were laminated in this order. The laminate was cut with a cutter to obtain an adhesive sheet (adhesive tape: width 20 mm) and subjected to an adhesive strength measurement test described later. The separator was removed at each measurement described later. In the following description, the example number of the adhesive composition will also be treated as the example number of the adhesive sheet prepared using the same and the adhesive strength evaluation thereof. Details of each component and the support used are shown in Table 1.

[0026] [Table 1]

[0027] As a reference example, two types of temperature-sensitive adhesive sheets (Intellimer) manufactured by Nitta Corporation are TM Tape cool-off type Plafix, product numbers CS2325NA2 (Reference Example 1: NA2) and CS2325NA4 (Reference Example 2: NA4) were used and subjected to the adhesive strength measurement test described below.

[0028] <Adhesive strength measurement test> The adhesive strength of the pressure-sensitive adhesive sheets of Examples 1 to 26 and the pressure-sensitive adhesive sheets of Reference Examples 1 and 2 was measured in accordance with JIS Z0237. Specifically, the pressure-sensitive adhesive sheet was first cut as necessary to obtain a 20 mm-wide rectangular test sample for measuring adhesive strength. The test sample, the BA-SUS plate as the adherend, and the pressure roller used in the test were allowed to stand at each of the prescribed temperatures shown in Table 3 (adhesive strength measurement temperature: 0°C to 50°C) for 120 minutes or more to allow temperature acclimation. Then, under the specified temperature environment, the test sample was attached to a BA-SUS plate by rolling it back and forth twice at a speed of 300 mm / min with a 2 kg rubber roll. Then, under the specified temperature environment, the test sample was peeled off from the BA-SUS plate within 1 minute after attachment under the conditions of a peel angle of 180° and a peel speed of 300 mm / min, and the adhesive strength (N / 20 mm) was measured. The obtained measured value was divided by 2 to convert it to an adhesive strength (N / 10 mm) per 10 mm width. The results are shown in Tables 2 to 4.

[0029] [Table 2]

[0030] [Table 3]

[0031] [Table 4]

[0032] As shown in Tables 2 and 3, the pressure-sensitive adhesive sheets of Examples 1 to 21 have a lower limit adhesive strength development temperature T at which the adhesive strength against a BA-SUS plate can be maintained at a level of 0.15 N / 10 mm or more in the temperature range of 10° C. or more and 25° C. or less. low and at a temperature 5° C. lower than the lower limit temperature, the adhesive strength is 0.12 N / 10 mm or less. Furthermore, as shown in Table 4, the adhesive sheet of Example 22, which used a SIS block copolymer commonly used in the fields of adhesive sheets and patches as the elastomer, exhibited and maintained a high adhesive strength of 4 N / 10 mm or more in the temperature range of 10°C to 25°C, and maintained a high adhesive strength of 3 N / 10 mm even in an environment of 5°C, which is 5°C lower than 10°C, and exhibited adhesive behavior in which the adhesive strength decreased in higher temperature ranges. The pressure-sensitive adhesive sheets of Examples 23 to 26 did not exhibit a level of adhesive strength to BA-SUS plate of 0.15 N / 10 mm or more (0.01 N or less) in the temperature range of 10° C. to 25° C. These pressure-sensitive adhesive sheets had no tackiness of the adhesive in the temperature range of 25° C. or less, and did not exhibit any adhesive strength at all. Furthermore, Reference Examples 1 and 2, which are commercially available temperature-sensitive adhesive sheets, exhibited adhesive behavior in which the adhesive strength reached a maximum at 35° C. to 40° C. The adhesive sheets of Reference Examples 1 and 2 also had no tackiness at all in the temperature range of 25° C. or lower, and no adhesive strength was expressed at all.

[0033] As described above, according to the present invention, adhesive strength is exhibited at room temperature (25° C.) or below, and adhesive strength is maintained. It is possible to provide a heat-sensitive adhesive composition and a heat-sensitive adhesive sheet in which the adhesive strength is reduced by lowering the temperature below the temperature at which the adhesive strength is expressed.

Claims

1. A heat-sensitive adhesive composition containing a 4-methyl-1-pentene / α-olefin copolymer as an elastomer component, The adhesive sheet, which has an adhesive layer made of the heat-sensitive adhesive composition provided on at least one surface of a substrate, has an adhesive strength to a BA-SUS plate of 0.15 N / 10 mm or more in a temperature range of 10° C. to 25° C., and the adhesive strength is the lowest adhesive strength development temperature T ｌｏｗ and the lower limit of the adhesive strength development temperature T ｌｏｗ 5°C lower than the temperature (T ｌｏｗ At -5°C, the adhesive strength against BA-SUS plate is 0.12 N / 10 mm or less. Adhesive composition.

2. The 4-methyl-1-pentene / α-olefin copolymer is a copolymer containing 70 mol % to 90 mol % of a unit structure derived from 4-methyl-1-pentene, 10 mol % to 30 mol % of a unit structure derived from an α-olefin having 2 or 3 carbon atoms, and 0 to 10 mol % of other unit structures (however, the total of all unit structures is 100 mol %); The pressure-sensitive adhesive composition according to claim 1 .

3. The pressure-sensitive adhesive composition further contains a tackifier resin and a softener. The pressure-sensitive adhesive composition according to claim 1 .

4. The tackifier resin is at least one selected from the group consisting of an aliphatic hydrocarbon resin, an aromatic modified terpene resin, and an alicyclic hydrogenated petroleum resin. The pressure-sensitive adhesive composition according to claim 3.

5. The softener is at least one selected from the group consisting of oils, waxes, and polybutene. The pressure-sensitive adhesive composition according to claim 3.

6. A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to claim 1 on at least one surface of the substrate.

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