JP6974405B2 - (Meta) Acrylic adhesives and adhesive tapes - Google Patents

Description

The present invention relates to a (meth) acrylic pressure-sensitive adhesive using a (meth) acrylic copolymer and a cross-linking agent. The present invention also relates to an adhesive tape provided with the above (meth) acrylic pressure-sensitive adhesive.

Conventionally, gorilla glass has been widely used as a cover glass for smartphones and the like. When gorilla glass is used as the cover glass, scratches and cracks can be suppressed to some extent. However, it may be further required to suppress the occurrence of scratches and cracks. Therefore, as an alternative material to gorilla glass, sapphire glass having high hardness has been attracting attention in recent years.

By the way, a cover glass of a smartphone or the like is usually used by being polished to make it smooth. The polishing process is performed using a polishing cloth fixed to the surface plate of the polishing machine. Adhesive tape is usually used to secure the polishing cloth to the surface plate of the polishing machine.

Further, a (meth) acrylic pressure-sensitive adhesive is used for the double-sided pressure-sensitive adhesive tape. The following Patent Document 1 contains a (meth) acrylic acid alkyl ester, an acrylic polymer composed of a carboxyl group-containing monomer and a hydroxyl group-containing monomer as monomer components, a tackifier resin, and a pressure-sensitive adhesive. Adhesive tapes formed by the agent composition are disclosed. The adhesive tape of Patent Document 1 is used for fixing a lens of a mobile phone, fixing a key module member of a mobile phone, an impact material of an electronic device, fixing a decoration panel of a TV, a battery pack protection application of a personal computer, and a lens waterproof of a digital video camera. It can be used for various purposes.

Japanese Unexamined Patent Publication No. 2011-252095

Patent Document 1 does not particularly describe the use of an adhesive tape for fixing the polishing cloth to the surface plate of the polishing machine in the polishing process. Although it is not the application described in Patent Document 1, if the polishing cloth is fixed with an adhesive tape as in Patent Document 1 and a hard material such as glass is polished for a long time, the polishing cloth is peeled off from the adhesive tape. Sometimes. In particular, the harder the hard material, the easier it is for the polishing cloth to peel off from the adhesive tape during polishing. As a result of diligent studies by the inventors of the present application on the cause of this, high pressure and heat are applied to the adhesive tape when polishing a hard material. It was found that the polishing cloth was easily peeled off.

An object of the present invention is to provide a (meth) acrylic pressure-sensitive adhesive having excellent shear adhesive strength at high temperatures, and an adhesive tape provided with the (meth) acrylic pressure-sensitive adhesive.

According to a broad aspect of the present invention, the (meth) acrylic copolymer comprises a (meth) acrylic material in which a crosslinkable composition containing a (meth) acrylic copolymer and a cross-linking agent has been cross-linked, and the (meth) acrylic copolymer is described. It is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer and a hydroxyl group-containing monomer, and in the mixed monomer, the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer. The content of the hydroxyl group-containing monomer is 0.1 parts by weight or more, 0.3 parts by weight or less, and the gel content is 53% by weight or more with respect to 100 parts by weight of the (meth) acrylic pressure-sensitive adhesive. Is provided.

In certain aspects of the (meth) acrylic pressure-sensitive adhesive according to the present invention, it comprises a tackifier resin having a softening point of 130 ° C. or higher.

In a specific aspect of the (meth) acrylic pressure-sensitive adhesive according to the present invention, the content of the tackifier resin with respect to 100 parts by weight of the (meth) acrylic material is 35 parts by weight or more and 43 parts by weight or less.

In a specific aspect of the (meth) acrylic pressure-sensitive adhesive according to the present invention, the shear storage elastic modulus at a frequency of 10 Hz and a temperature of 80 ° C. is 5.0 × 10 ⁴ Pa or more.

In certain aspects of the (meth) acrylic pressure-sensitive adhesive according to the present invention, the hydroxyl group-containing monomer is hydroxyalkyl (meth) acrylate.

According to a broad aspect of the present invention, the substrate comprises a substrate and a first pressure-sensitive adhesive layer laminated on the first surface of the substrate, the first pressure-sensitive adhesive layer being configured according to the present invention. Adhesive tapes, which are (meth) acrylic pressure-sensitive adhesives, are provided.

According to a broad aspect of the invention, a substrate, a first pressure-sensitive adhesive layer laminated on a first surface of the substrate, and a second surface opposite to the first surface of the substrate. A (meth) acrylic pressure-sensitive adhesive having a second pressure-sensitive adhesive layer laminated on the surface, and the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are each configured according to the present invention, and both sides thereof. Adhesive tapes, which are adhesive tapes, are provided.

In certain aspects of the adhesive tape according to the present invention, it is used to fix the polishing cloth to the surface plate of the polishing machine.

In a specific aspect of the adhesive tape according to the present invention, it is used to fix a polishing cloth to the surface plate of the polishing machine when polishing a hard material having a Vickers hardness of 7 or more by using a polishing machine.

In certain aspects of the adhesive tape according to the present invention, when polishing sapphire glass using a polishing machine, it is used to fix the polishing cloth to the surface plate of the polishing machine.

The (meth) acrylic pressure-sensitive adhesive according to the present invention contains a (meth) acrylic material in which cross-linking of a cross-linking composition containing a (meth) acrylic copolymer and a cross-linking agent is promoted, and the above-mentioned (meth) acrylic is used together. The polymer is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer, and a hydroxyl group-containing monomer, and in the mixed monomer, the (meth) acrylic acid ester monomer and the (meth) acrylic acid ester monomer and (meth). ) The content of the hydroxyl group-containing monomer is 0.1 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the total amount of the acrylic acid monomer, and the gel content is 53% by weight or more, so that the temperature is high. Has excellent shear adhesive strength.

FIG. 1 is a schematic front sectional view of an adhesive tape according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining a method for testing a holding force. FIG. 3 is a schematic diagram for explaining a test method of shear adhesive force. FIG. 4 is a schematic diagram for explaining the method of the cohesive force test.

Hereinafter, the details of the present invention will be described.

The (meth) acrylic pressure-sensitive adhesive according to the present invention includes a (meth) acrylic material in which cross-linking of a cross-linking composition containing a (meth) acrylic copolymer and a cross-linking agent is promoted. The (meth) acrylic copolymer is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer, and a hydroxyl group-containing monomer. In the mixed monomer, the content of the hydroxyl group-containing monomer is 0.1 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the total amount of the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer. .. The gel fraction of the (meth) acrylic pressure-sensitive adhesive according to the present invention is 53% by weight or more.

Since the (meth) acrylic pressure-sensitive adhesive according to the present invention has the above-mentioned structure, it has excellent shear pressure-sensitive adhesive strength at high temperatures.

Further, in the adhesive tape according to the present invention, the pressure-sensitive adhesive layer, which is the (meth) acrylic pressure-sensitive adhesive, is laminated on the surface of at least one side of the base material. Therefore, when the polishing cloth is fixed to the surface plate using the adhesive tape of the present invention, the polishing cloth is difficult to peel off even if the hard material is polished. Therefore, the adhesive tape of the present invention is excellent in reliability. In particular, when polishing a hard material, it is necessary to polish at high speed, at high pressure, or for a long time. Therefore, when polishing a hard material, the adhesive tape is exposed to a higher temperature. In the present invention, since the shear adhesive force at high temperature can be increased, the adhesive tape can be suitably used when polishing a hard material.

In particular, the (meth) acrylic pressure-sensitive adhesive according to the present invention and the pressure-sensitive adhesive tape according to the present invention can be suitably used for polishing hard materials having a Vickers hardness of 7 or more and sapphire glass. For example, conventional (meth) acrylic adhesives and adhesive tapes, even if they can be applied to the polishing process of gorilla glass, cannot be applied to the polishing process of hard materials with higher Vickers hardness than gorilla glass and sapphire glass. There is. In the present invention, even if it is a hard material having a considerably high altitude, it is possible to sufficiently suppress the peeling of the polishing cloth during the polishing process.

[(Meta) acrylic adhesive]
The (meth) acrylic pressure-sensitive adhesive according to the present invention includes a (meth) acrylic material. The (meth) acrylic material is a composition in which cross-linking of a cross-linking composition containing a (meth) acrylic copolymer and a cross-linking agent is promoted. The (meth) acrylic material includes a crosslinked product in which cross-linking of the (meth) acrylic copolymer is advanced by a cross-linking agent. The (meth) acrylic material may contain an unreacted (meth) acrylic copolymer and a cross-linking agent that do not contribute to cross-linking. The degree of progress of cross-linking is appropriately adjusted in consideration of the gel fraction and the like.

The (meth) acrylic copolymer is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer, and a hydroxyl group-containing monomer. In the mixed monomer, the content of the hydroxyl group-containing monomer is 0.1 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the total amount of the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer. ..

The gel fraction of the (meth) acrylic pressure-sensitive adhesive of the present invention is 53% by weight or more. When the gel fraction is at least the above lower limit, the cohesive force of the (meth) acrylic pressure-sensitive adhesive is enhanced. Further, from the viewpoint of further enhancing the adhesive strength of the (meth) acrylic pressure-sensitive adhesive, the gel fraction is preferably 62% by weight or less.

The gel fraction is measured as follows.

W1 (g) of the (meth) acrylic pressure-sensitive adhesive is collected, and the insoluble matter when the collected (meth) acrylic pressure-sensitive adhesive is immersed in ethyl acetate at 23 ° C. for 24 hours is filtered through a 200-mesh wire mesh. .. The residue on the wire mesh is heated and dried at 110 ° C., and the weight W2 (g) of the obtained dried residue is measured. The gel fraction (crosslinking degree) is calculated by the following formula (1).

Gel fraction (% by weight) = 100 x W2 / W1 ... (1)

From the viewpoint of achieving both the adhesive force and the cohesive force of the (meth) acrylic adhesive at a high level and further enhancing the shear adhesive force at high temperature, the gel content of the (meth) acrylic adhesive is 55 weight by weight. % Or more, preferably 65% by weight or less, and more preferably 62% by weight or less.

Further, the (meth) acrylic pressure-sensitive adhesive of the present invention preferably has a shear storage elastic modulus of 5.0 × 10 ⁴ Pa or more at a frequency of 10 Hz and a temperature of 80 ° C. When the shear storage elastic modulus is at least the above lower limit, the cohesive force of the (meth) acrylic pressure-sensitive adhesive can be further increased. Further, from the viewpoint of further enhancing the adhesive strength of the (meth) acrylic pressure-sensitive adhesive, the shear storage elastic modulus is ^{preferably 10 × 10 4} Pa or less.

The shear storage elastic modulus is measured by dynamic viscoelasticity measurement. The dynamic viscoelasticity measurement is performed using a dynamic viscoelasticity measuring device in a solid shear mode under the conditions of a frequency of 10 Hz and a strain of 0.1%.

From the viewpoint of achieving both the adhesive force and the cohesive force of the (meth) acrylic adhesive at a high level and further enhancing the shear adhesive force at high temperatures, the shear storage elastic modulus of the (meth) acrylic adhesive is 6. It is preferable that it is × 10 ^{4 Pa or more.}

Hereinafter, the details of the materials constituting the (meth) acrylic pressure-sensitive adhesive of the present invention will be described.

((Meta) acrylic material)
The (meth) acrylic material is a composition in which cross-linking of a cross-linking composition containing a (meth) acrylic copolymer and a cross-linking agent is promoted.

(Meta) acrylic copolymer;
The (meth) acrylic copolymer is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer, and a hydroxyl group-containing monomer.

The (meth) acrylic acid ester monomer is not particularly limited, and is, for example, an alkyl such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth) acrylate. Alkyl esters of (meth) acrylic acid having 1-3 carbon atoms; butyl (meth) acrylate; tridecyl (meth) acrylic acid, stearyl (meth) acrylic acid, and other alkyl groups having 13 to 18 carbon atoms ( Meta) Acrylic acid alkyl ester can be mentioned. The above (meth) acrylic acid ester monomer may be used alone or in combination of two or more.

The content of the (meth) acrylic acid ester monomer in 100% by weight of the mixed monomer is preferably 75% by weight or more, preferably 100% by weight or less. The content of the (meth) acrylic acid monomer in 100% by weight of the mixed monomer is preferably 3% by weight or more, preferably 7% by weight or less.

The hydroxyl group-containing monomer is not particularly limited, and is, for example, (meth) hydroxyalkyl acrylate such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; allyl. Examples thereof include alcohol and (meth) acrylic acid ester having a diethylene glycol group. The hydroxyl group-containing monomer may be used alone or in combination of two or more. From the viewpoint of further enhancing the shear adhesive force of the (meth) acrylic pressure-sensitive adhesive at high temperatures, the hydroxyl group-containing monomer is preferably hydroxyalkyl (meth) acrylate.

In the mixed monomer, the content of the hydroxyl group-containing monomer is 0.1 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the total amount of the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer. .. Since the content of the hydroxyl group-containing monomer is not less than the above lower limit and not more than the above upper limit, the (meth) acrylic pressure-sensitive adhesive of the present invention is excellent in shear adhesive force at high temperature. From the viewpoint of further enhancing the shear adhesive force of the (meth) acrylic pressure-sensitive adhesive at high temperatures, the content of the hydroxyl group-containing monomer with respect to 100 parts by weight of the total amount of the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer is , 0.1 part by weight or more and preferably 0.2 parts by weight or less.

The mixed monomer may contain other polymerizable monomers that can be copolymerized, if necessary.

Examples of the other copolymerizable monomer include isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycerin dimethacrylate, glycidyl (meth) acrylate, 2-methacryloyloxyethyl isocyanate, and itaconic acid. Examples thereof include functional monomers such as acid, maleic anhydride, crotonic acid, maleic acid, and fumaric acid.

The weight average molecular weight (Mw) of the (meth) acrylic polymer is not particularly limited, but is preferably 650,000 or more, preferably 1.2 million or less. When the weight average molecular weight (Mw) is equal to or higher than the lower limit and lower than the upper limit, the adhesive force and the cohesive force of the (meth) acrylic pressure-sensitive adhesive can be compatible at a high level, and the shear adhesive force at a high temperature can be achieved. Can be further enhanced.

In order to adjust the weight average molecular weight (Mw) to the above range, the polymerization conditions such as the polymerization initiator and the polymerization temperature may be adjusted. The weight average molecular weight (Mw) indicates the polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC).

To obtain the (meth) acrylic copolymer by copolymerizing the mixed monomer, for example, the mixed monomer is subjected to a radical reaction in the presence of a polymerization initiator. As a method for radically reacting the mixed monomer, that is, a polymerization method, a conventionally known method is used. Examples of the polymerization method include a solution polymerization method (boiling point polymerization method or constant temperature polymerization method), an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method and the like.

The polymerization initiator is not particularly limited, and examples thereof include organic peroxides and azo compounds. 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-butylper Examples thereof include oxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate and the like. Examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. The above-mentioned polymerization initiator may be used alone or in combination of two or more.

Crosslinker;
In the (meth) acrylic material, the cross-linking of the (meth) acrylic copolymer is proceeding with the cross-linking agent.

The cross-linking agent is not particularly limited, and for example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, a melamine-based cross-linking agent, a peroxide-based cross-linking agent, a urea-based cross-linking agent, a metal alkoxide-based cross-linking agent, and a metal chelate-based cross-linking agent. Examples thereof include agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and amine-based cross-linking agents. The above-mentioned cross-linking agent may be used alone or in combination of two or more.

From the viewpoint of further enhancing the shear adhesive force of the (meth) acrylic pressure-sensitive adhesive at high temperatures, the cross-linking agent preferably contains the isocyanate-based cross-linking agent.

Examples of the isocyanate-based cross-linking agent include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate. , Alicyclic polyisocyanates such as hydrogenated tolylene diisocyanate and hydrogenated xylene diisocyanate; aromatics such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate. Examples include polyisocyanate. The isocyanate-based cross-linking agent may be used alone or in combination of two or more.

In the crosslinkable composition before the progress of crosslinking, the content of the crosslinking agent is not particularly limited, but is 1.5 parts by weight or more and 4 parts by weight with respect to 100 parts by weight of the (meth) acrylic copolymer. It is preferably less than or equal to a portion. When the content of the cross-linking agent is not less than the above lower limit and not more than the above upper limit, the adhesive force and the cohesive force of the (meth) acrylic pressure-sensitive adhesive can be compatible at a high level, and the shear adhesive force at a high temperature can be obtained. It can be further enhanced.

(Adhesive-imparting resin)
The (meth) acrylic pressure-sensitive adhesive of the present invention may further contain a tack-imparting resin. The (meth) acrylic pressure-sensitive adhesive of the present invention may contain the above-mentioned (meth) acrylic material and a tackifier resin.

The tackifier resin is not particularly limited, but is, for example, a petroleum-based resin such as an aliphatic copolymer, an aromatic copolymer, an aliphatic / aromatic copolymer, and an alicyclic copolymer. Examples thereof include kumaron-inden-based resin; terpene-based resin; terpenephenol-based resin; rosin-based resin such as polymerized rosin; phenol-based resin; xylene-based resin and the like. These resins may be hydrogenated resins. The tackifier resin may be used alone or in combination of two or more.

From the viewpoint of achieving both the adhesive strength and the cohesive strength of the (meth) acrylic adhesive at a high level and further enhancing the shear adhesive strength at high temperatures, the softening point of the tackifier resin should be 110 ° C. or higher. It is preferably 130 ° C. or higher, more preferably 150 ° C. or higher, and more preferably 170 ° C. or lower.

The content of the tackifier resin is not particularly limited, but is preferably 30 parts by weight or more, more preferably 35 parts by weight or more, based on 100 parts by weight of the (meth) acrylic material. It is preferably 50 parts by weight or less, and more preferably 43 parts by weight or less. When the content of the tackifying resin is equal to or higher than the lower limit and lower than the upper limit, the adhesive force and the cohesive force of the (meth) acrylic pressure-sensitive adhesive can be compatible at a high level, and the shear adhesive force at a high temperature can be achieved. Can be further enhanced.

The (meth) acrylic pressure-sensitive adhesive further contains conventionally known additives such as a filler, an antioxidant, and an ultraviolet absorber, if necessary, within a range that does not impair the effects of the present invention. May be good.

Further, the tackifier resin may be mixed with the crosslinkable composition before proceeding with the crosslinking of the crosslinkable composition, or may be used by advancing the crosslinking of the crosslinkable composition (meth) acrylic. After obtaining the material, it may be mixed with the above (meth) acrylic material and used.

[Adhesive tape]
Hereinafter, specific embodiments of the adhesive tape according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic front sectional view showing an adhesive tape according to an embodiment of the present invention. As shown in FIG. 1, the pressure-sensitive adhesive tape 1 includes a base material 2, a first pressure-sensitive adhesive layer 3, and a second pressure-sensitive adhesive layer 4.

The base material 2 has a first surface 2a and a second main surface 2b. The first surface 2a and the second surface 2b face each other. The first pressure-sensitive adhesive layer 3 is laminated on the first surface 2a. A second pressure-sensitive adhesive layer 4 is laminated on the second surface 2b. The adhesive tape 1 is a double-sided adhesive tape in which adhesive layers are provided on both sides of the base material 2. In the present invention, the pressure-sensitive adhesive layer may be provided only on one surface of the base material 2. More specifically, the first pressure-sensitive adhesive layer 3 may be provided only on the first surface 2a of the base material 2, or the second pressure-sensitive adhesive layer 4 may be provided only on the second surface 2b. It may be provided.

The material of the base material 2 is not particularly limited, and examples thereof include synthetic resin films such as polyester-based resin and polypropylene-based resin. Among them, the material is flat, has a small thickness fluctuation, and has a certain strength. Therefore, a polyester-based resin film can be preferably used.

The first and second pressure-sensitive adhesive layers 3 and 4 are the (meth) acrylic pressure-sensitive adhesives of the present invention described above.

In the present invention, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be the above-mentioned (meth) acrylic pressure-sensitive adhesives, respectively, and only the first pressure-sensitive adhesive layer is described above (meth). ) It may be an acrylic pressure-sensitive adhesive.

The thicknesses of the first and second pressure-sensitive adhesive layers are not particularly limited, but are preferably 30 μm or more, more preferably 50 μm or more, preferably 100 μm or less, and more preferably 90 μm or less.

The pressure-sensitive adhesive tape according to the present invention, such as the pressure-sensitive adhesive tape 1, has the above-mentioned structure, and since the pressure-sensitive adhesive layer is the (meth) acrylic pressure-sensitive adhesive of the present invention, it is excellent in shear adhesive strength at high temperatures. Therefore, when the polishing cloth is fixed to the surface plate by using the (meth) adhesive tape of the present invention when polishing a hard material using a polishing machine, the polishing cloth is not easily peeled off from the adhesive by polishing.

The (meth) acrylic pressure-sensitive adhesive and the pressure-sensitive adhesive tape of the present invention can be suitably used for fixing a polishing cloth to a surface plate of a polishing machine. In particular, since the (meth) acrylic pressure-sensitive adhesive and the pressure-sensitive adhesive tape of the present invention have excellent shear adhesive strength at high temperatures, the platen of the above-mentioned polishing machine is used when polishing a hard material having a Vickers hardness of 7 or more. It can be more preferably used for fixing a polishing cloth to a cloth. Sapphire glass can be preferably used as the hard material having a Vickers hardness of 7 or more.

When the adhesive tape of the present invention is used for fixing the polishing pad to the platen of the polishing machine, it is applied to the surface of the base material on the polishing pad side from the viewpoint of suppressing the polishing pad from peeling from the adhesive layer. It is desirable that a pressure-sensitive adhesive layer, which is the (meth) acrylic pressure-sensitive adhesive of the present invention, is provided.

(Other details of adhesive tape)
Examples of the method for producing the adhesive tape of the present invention include the following methods.

First, a tackifier resin or the like is added to the (meth) acrylic polymer and the cross-linking agent, if necessary, and a solvent is added to prepare a solution of the pressure-sensitive adhesive. A solution of this adhesive is applied to one side surface of the substrate. The solvent in the solution is dried and removed, and the (meth) acrylic polymer is crosslinked to form a pressure-sensitive adhesive layer. Next, the release film is superposed on the formed pressure-sensitive adhesive layer so that the release-treated surface faces the pressure-sensitive adhesive layer. As a result, an adhesive tape having a laminated structure of a release film / adhesive layer / base material can be obtained. When the adhesive tape is a double-sided adhesive tape, the adhesive tape can be manufactured by forming an adhesive layer on the other side surface of the base material in the same manner.

The solvent for preparing the solution of the pressure-sensitive adhesive is not particularly limited, and examples thereof include ethyl acetate, toluene, dimethyl sulfoxide, ethanol, acetone, and diethyl ether.

Examples of the method for drying the solvent include a method of putting it in a drying oven such as an IR heater or an oven to dry it. Drying may be carried out under normal pressure or under reduced pressure.

The shape of the adhesive tape of the present invention is not particularly limited, and examples thereof include a rectangular shape, a circular shape, an elliptical shape, and an annular shape.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples.

(Example 1)
Preparation of (meth) acrylic adhesive;
95 parts by weight of butyl acrylate (BA), 5 parts by weight of acrylic acid (AAc), 0.1 part by weight of 2-hydroxyethyl acrylate (HEA) in a reaction device equipped with a stirrer, a cooler, a thermometer and a nitrogen gas inlet. A reaction solution containing 100 parts by weight of ethyl acetate as a solvent was charged with the mixed monomer, and the dissolved oxygen was removed by bubbling with nitrogen gas for 30 minutes.

Then, the inside of the apparatus was replaced with nitrogen gas, and the temperature of the reaction solution was raised in an oil bath until the reaction solution reached the reflux temperature while stirring the reaction solution. When the reaction solution reaches the reflux temperature, a polymerization initiator solution prepared by dissolving 0.1 part by weight of azobisisobutyronitrile in 1.35 parts by weight of cyclohexane is added to the reaction solution over 7 hours to add a mixed monomer. Copolymerized. To the acrylic copolymer solution obtained after the completion of polymerization, 2.9 parts by weight of coronate as a cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "L-55") and terpenphenol resin as a tackifying resin (manufactured by Yasuhara Chemical Co., Ltd.) , Trade name "T160", softening point 160 ° C.) 40 parts by weight was added and stirred to prepare a pressure-sensitive adhesive solution.

Preparation of double-sided adhesive tape;
A polyethylene terephthalate film having a mold release treatment on one side was prepared. The pressure-sensitive adhesive solution obtained above is applied to the release-treated surface of this polyethylene terephthalate film so that the thickness after drying is 80 μm, dried at 110 ° C. for 5 minutes, and the acrylic in the acrylic copolymer solution is used. Crosslinking of the copolymer was promoted to prepare a laminated sheet having an adhesive layer on the release-treated surface of the polyethylene terephthalate film. In the same manner, another laminated sheet was produced to obtain a total of two laminated sheets.

Next, a polyethylene terephthalate film (thickness 23 μm) was prepared as a base material. One of the above laminated sheets was laminated on the surface of one side of the base material from the pressure-sensitive adhesive layer surface, and the pressure-sensitive adhesive layer was transferred to the base material and integrated by laminating. The other laminated sheet was laminated on the other surface of the base material from the pressure-sensitive adhesive layer surface, and the pressure-sensitive adhesive layer was transferred to the base material and integrated by laminating. As a result, a double-sided adhesive tape having an adhesive layer having a thickness of 80 μm provided on both sides of the base material was obtained.

(Examples 2 to 4, Reference Examples 5 and 6 and Comparative Examples 1 to 4)
Select a monomer from butyl acrylate (BA), acrylic acid (AAac), 2-ethylhexyl acrylate (2EHA), 2-hydroxyethyl acrylate (HEA), vinyl acetate (VAc) and methyl methacrylate (MMA). The same as in Example 1 except that the mixed monomers mixed at the mixing ratio shown in Table 1 below were used, and the gel fraction was set as shown in Table 1 below by adjusting the drying conditions. And obtained a double-sided adhesive tape.

(Example 7)
A polymerized rosin ester (manufactured by Arakawa Chemical Industry Co., Ltd., trade name "D160", softening point 160 ° C.) was used as the tackifying resin, and the drying conditions were adjusted to set the gel fraction as shown in Table 1 below. A double-sided adhesive tape was obtained in the same manner as in Example 1.

(Example 8)
As the tackifying resin, terpene phenol (manufactured by Yasuhara Chemical Co., Ltd., trade name "T160", softening point 160 ° C.) and polymerized rosin ester (manufactured by Arakawa Chemical Industry Co., Ltd., trade name "D160", softening point 160 ° C.) are listed in Table 1 below. A double-sided adhesive tape was obtained in the same manner as in Example 1 except that the mixture ratio was used as shown and the gel fraction was set as shown in Table 1 below by adjusting the drying conditions.

( Reference example 9)
Except for the fact that Nikanol (manufactured by Fudo Chemical Co., Ltd., trade name "HP120", softening point 120 ° C.) was used as the tackifier resin, and that the gel fraction was set as shown in Table 1 below by adjusting the drying conditions. Obtained a double-sided adhesive tape in the same manner as in Example 1.

<Evaluation>
(Meta) acrylic pressure-sensitive adhesive (adhesive) constituting the double-sided adhesive tape and double-sided adhesive tape obtained in Examples 1 to 4, Reference Examples 5 and 6, Examples 7 and 8, Reference Example 9 and Comparative Examples 1 to 4. The (meth) acrylic copolymer used for the agent layer) and the (meth) acrylic pressure-sensitive adhesive was evaluated as follows. The results are shown in Table 1 below.

(1) Molecular Weight of (Meta) Acrylic Copolymer For the (meth) acrylic copolymer before cross-linking used to prepare the double-sided adhesive tape, a column (manufactured by Showa Denko Co., Ltd., product name "LF-804") was used. It was analyzed by gel permeation chromatography (GPC) and polystyrene-converted to determine the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the (meth) acrylic copolymer.

(2) Tg
Using a dynamic viscoelasticity measuring device (manufactured by IT Measurement Control Co., Ltd., product number "DVA-310"), in solid shear mode, frequency 10 Hz, strain 0.1%, temperature -40 ° C to 140 ° C, temperature rise. Dynamic viscoelasticity measurement of (meth) acrylic pressure-sensitive adhesive (adhesive layer) test piece (thickness 1.2 mm, length 11 mm x width 6 mm) was performed under the condition of a speed of 3 ° C./min, and it is the peak value of tan δ. Tg was measured.

(3) Gel fraction W1 (g) of (meth) acrylic adhesive (adhesive layer) was collected from the double-sided adhesive tape, and the collected adhesive was immersed in ethyl acetate at 23 ° C for 24 hours. The lysate was filtered through a 200 mesh wire mesh. The residue on the wire mesh was heated and dried at 110 ° C., the weight W2 (g) of the obtained dried residue was measured, and the gel fraction (crosslinking degree) was calculated by the following formula (1).

Gel fraction (% by weight) = 100 x W2 / W1 ... (1)

(4) Shear storage elastic modulus (meth) The shear storage elastic modulus of the acrylic pressure-sensitive adhesive (adhesive layer) was measured by dynamic viscoelasticity measurement. The above dynamic viscoelasticity measurement is performed in a solid shear mode using a dynamic viscoelasticity measuring device (manufactured by IT Measurement Control Co., Ltd., product number "DVA-310"), frequency 10 Hz, strain 0.1%, temperature-. The measurement was performed under the conditions of 40 ° C. to 140 ° C. and a heating rate of 3 ° C./min under the conditions of a (meth) acrylic pressure-sensitive adhesive (tacky agent layer) test piece (thickness 1.2 mm, length 11 mm × width 6 mm).

(5) Holding force FIG. 2 is a schematic diagram for explaining a holding force test method. As shown in FIG. 2, the test piece 5 and the first SUS plate 7 are bonded to each other using the double-sided adhesive tape 6 produced by the above method, and then a 1 kg first weight 8 is attached to one end of the test piece 5. It was lowered and the distance of the deviation after 1 hour and 24 hours was measured at a temperature of 100 ° C.

(6) High-temperature shearing adhesive force A double-sided adhesive tape cut out to a size of 10 × 10 mm is sandwiched between two aluminum plates, then ^{crimped at a pressure of 2} kg / cm 2 for 20 minutes, and then at 40 ° C. and 0.3 MPa. Two aluminum plates were attached by crimping using an autoclave (manufactured by Hirayama Seisakusho Co., Ltd., model number "PTU30SVIII") to obtain a test piece. The prepared test piece was stored in an oven at 80 ° C. for 1 hour, and then the shear adhesive force was measured at a rate of 200 mm / min in an atmosphere of 80 ° C. More specifically, as shown in FIG. 3, both ends of the first and second aluminum plates 9 and 10 bonded by the double-sided adhesive tape 6 are pulled in the direction of the arrow shown in FIG. 3, and the joint is broken. The maximum load was measured.

(7) Cohesive force test FIG. 4 is a schematic diagram for explaining a method of the cohesive force test. As shown in FIG. 4, the second and third SUS plates 11 and 12 at 80 ° C. are bonded together with a 40 mm × 20 mm double-sided adhesive tape 6, one end of the second SUS plate 11 is fixed, and the third SUS is fixed. The displacement amount when the second weight 13 of 200 g was hung on one end of the plate 12 for 3 minutes was measured, and the return amount after 3 minutes was precisely measured by removing the second weight 13.

(8) Polishing machine evaluation Both sides obtained in Examples 1 to 4, Reference Examples 5 and 6, Examples 7 and 8, Reference Example 9 and Comparative Examples 1 to 4 on the surface of a sapphire substrate having a thickness of 500 μm and a diameter of 6 inches. The work with the adhesive tape attached was used. The double-sided adhesive tape side of the sapphire substrate, which is the work, is vacuum-sucked to the suction head of the polishing device, and then the suction head is rotated and lowered at 100 rpm to slide the sapphire surface on the polishing surface plate rotating at 120 rpm. The polishing process was started while rubbing and applying a pressure of 120 g / cm ² , and the polishing process was completed when the allowance of 12 μm was reached. During the polishing process, a diamond abrasive grain dispersion polishing agent slurry liquid having a diameter of 0.5 to 1.5 μm was supplied onto the polishing surface plate. After 100 hours of these operations, the state of the polishing cloth adhered on the polishing platen was observed and evaluated according to the following evaluation criteria.

[Criteria for grinding machine evaluation]
◯… No peeling or floating was observed even after 100 hours of polishing.
Δ: Slight peeling or floating was observed to the extent that polishing could be continued before 100 hours had passed after polishing.
X ... Peeling or floating was observed before 100 hours had passed after polishing.

1 ... Adhesive tape 2 ... Base material 2a ... First surface 2b ... Second surface 3,4 ... First, second adhesive layer 5 ... Test piece 6 ... Double-sided adhesive tape 7, 11, 12 ... First , 2nd and 3rd SUS plates 8, 13 ... 1st and 2nd weights 9, 10 ... 1st and 2nd aluminum plates

Claims (5)

A crosslinked product of a crosslinkable composition comprising a (meth) acrylic copolymer and a crosslinking agent, comprising a (meth) acrylic material.
The (meth) acrylic copolymer is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer, and a hydroxyl group-containing monomer.
In the mixed monomer, the content of the hydroxyl group-containing monomer is 0.1 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the total amount of the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer. ,
The gel fraction is 53% by weight or more,
The shear storage elastic modulus at a frequency of 10 Hz and a temperature of 80 ° C. is 5.0 × 10 ⁴ Pa or more and 10 × 10 ⁴ Pa or less .
The content of the (meth) acrylic acid monomer in 100% by weight of the mixed monomer is 3% by weight or more.
(Meta) acrylic adhesives, excluding (meth) acrylic adhesives containing conductive particles. A crosslinked product of a crosslinkable composition comprising a (meth) acrylic copolymer and a crosslinking agent, comprising a (meth) acrylic material.
The (meth) acrylic copolymer is a copolymer of a mixed monomer containing a (meth) acrylic acid ester monomer, a (meth) acrylic acid monomer, and a hydroxyl group-containing monomer.
In the mixed monomer, the content of the hydroxyl group-containing monomer is 0.1 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the total amount of the (meth) acrylic acid ester monomer and the (meth) acrylic acid monomer. ,
The gel fraction is 55% by weight or more,
The shear storage elastic modulus at a frequency of 10 Hz and a temperature of 80 ° C. is 5.0 × 10 ⁴ Pa or more and 10 × 10 ⁴ Pa or less .
A (meth) acrylic pressure-sensitive adhesive in which the content of the (meth) acrylic acid monomer is 3% by weight or more in 100% by weight of the mixed monomer. The (meth) acrylic pressure-sensitive adhesive according to claim 2, excluding the (meth) acrylic pressure-sensitive adhesive containing conductive particles. With an adhesive layer,
An adhesive tape in which the pressure-sensitive adhesive layer is the (meth) acrylic pressure-sensitive adhesive according to any one of claims 1 to 3. The pressure-sensitive adhesive tape according to claim 4, wherein the pressure-sensitive adhesive layer has a thickness of 30 μm or more.

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