JP2017008327A - (meth)acrylic adhesive agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a (meth)acrylic adhesive agent excellent in shear adhesive power at high temperature.SOLUTION: The (meth)acrylic adhesive agent according to the present invention contains a (meth)acrylic material proceeding crosslink of a crosslinkable composition containing a (meth)acrylic copolymer and crosslinking agent, where the (meth)acrylic copolymer is a copolymer of a mixed monomer containing a (meth)acrylic ester monomer, a (meth)acrylic acid monomer and a hydroxyl group-containing monomer, the content of the hydroxyl group-containing monomer in the mixed monomer is 0.1 pt.wt. to 0.3 pt.wt. based on 100 pts.wt. of the total amount of the (meth)acrylic acid ester monomer and the (meth)acrylic acid monomer and gel fraction is 53 wt.% or more.SELECTED DRAWING: None

Description

  The present invention relates to a (meth) acrylic pressure-sensitive adhesive using a (meth) acrylic copolymer and a crosslinking agent. Moreover, this invention relates to an adhesive tape provided with the said (meth) acrylic-type 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, the suppression of the occurrence of scratches and cracks may be further demanded. Therefore, sapphire glass having high hardness has recently attracted attention as an alternative material for gorilla glass.

  By the way, a cover glass such as a smartphone is usually used by being smoothed by polishing. The polishing process is performed using a polishing cloth fixed to a surface plate of a polishing machine. Usually, an adhesive tape is used to fix the polishing cloth to the surface plate of the polishing machine.

  A (meth) acrylic pressure-sensitive adhesive is used for the double-sided pressure-sensitive adhesive tape. Patent Document 1 listed below includes a (meth) acrylic acid alkyl ester, a carboxyl group-containing monomer, and an acrylic polymer composed of a hydroxyl group-containing monomer as monomer components, a tackifier resin and a cross-linking agent. An adhesive tape formed by the agent composition is 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, impact material of an electronic device, fixing a decoration panel of a TV, protecting a battery pack of a personal computer, and waterproofing a lens of a digital video camera. It can be used for purposes.

JP 2011-252095 A

  Patent Document 1 does not specifically describe the use of an adhesive tape in order to fix the polishing cloth to the surface plate of the polishing machine in the polishing process. Although it is not the use described in Patent Document 1, if a 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 peels off from the adhesive tape. Sometimes. In particular, the harder the hard material, the easier the polishing cloth peels from the adhesive tape during polishing. As a result of intensive studies by the inventors of the present invention on this cause, high pressure and heat are applied to the adhesive tape when polishing a hard material. Therefore, in an adhesive tape with insufficient shear adhesive strength at high temperatures, It was found that the abrasive cloth was easy to peel off.

  The objective of this invention is providing the adhesive tape provided with the (meth) acrylic-type adhesive which is excellent in the shear adhesive force in high temperature, and this (meth) acrylic-type adhesive.

  According to a wide aspect of the present invention, the (meth) acrylic copolymer includes a (meth) acrylic material that has been subjected to crosslinking of a crosslinkable composition including a (meth) acrylic copolymer and a crosslinking agent, 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 (Meth) acrylic pressure-sensitive adhesive, wherein the content of the hydroxyl group-containing monomer is from 0.1 parts by weight to 0.3 parts by weight and the gel fraction is 53% by weight or more based on 100 parts by weight of the total Is provided.

  In a specific aspect of the (meth) acrylic pressure-sensitive adhesive according to the present invention, a tackifying resin having a softening point of 130 ° C. or higher is included.

  On the specific situation with the (meth) acrylic adhesive which concerns on this invention, content of the said tackifying resin with respect to 100 weight part of said (meth) acrylic materials is 35 weight part or more and 43 weight part 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 a specific aspect of the (meth) acrylic pressure-sensitive adhesive according to the present invention, the hydroxyl group-containing monomer is hydroxyalkyl (meth) acrylate.

  According to a wide aspect of the present invention, a substrate and a first pressure-sensitive adhesive layer laminated on the first surface of the substrate are provided, and the first pressure-sensitive adhesive layer is configured according to the present invention. An adhesive tape that is a (meth) acrylic adhesive is provided.

  According to a wide aspect of the present invention, a base material, a first pressure-sensitive adhesive layer laminated on the first surface of the base material, and a second opposite to the first surface of the base material A second pressure-sensitive adhesive layer laminated on the surface, and each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is a (meth) acrylic pressure-sensitive adhesive configured according to the present invention, An adhesive tape is provided that is an adhesive tape.

  In a specific aspect of the pressure-sensitive adhesive tape according to the present invention, the pressure-sensitive adhesive tape is used for fixing a polishing cloth to a surface plate of a polishing machine.

  In a specific aspect of the pressure-sensitive adhesive tape according to the present invention, when a hard material having a Vickers hardness of 7 or more is polished using a polishing machine, the pressure-sensitive adhesive tape is used for fixing a polishing cloth on a surface plate of the polishing machine.

  In a specific aspect of the pressure-sensitive adhesive tape according to the present invention, when polishing sapphire glass using a polishing machine, the adhesive tape is used for fixing a polishing cloth to a surface plate of the polishing machine.

  The (meth) acrylic pressure-sensitive adhesive according to the present invention includes a (meth) acrylic material in which crosslinking of a crosslinkable composition containing a (meth) acrylic copolymer and a crosslinking agent is advanced, 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. In the mixed monomer, the (meth) acrylic acid ester monomer and the (meta ) The content of the hydroxyl group-containing monomer with respect to 100 parts by weight of the total amount of acrylic acid monomers is 0.1 parts by weight or more and 0.3 parts by weight or less, and the gel fraction is 53% by weight or more. 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 holding force test method. FIG. 3 is a schematic diagram for explaining a test method of shear adhesive strength. FIG. 4 is a schematic diagram for explaining a cohesive strength test method.

  Details of the present invention will be described below.

  The (meth) acrylic pressure-sensitive adhesive according to the present invention includes a (meth) acrylic material in which crosslinking of a crosslinkable composition containing a (meth) acrylic copolymer and a crosslinking agent is advanced. 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 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 0.3 part by weight or less. . The gel fraction of the (meth) acrylic adhesive according to the present invention is 53% by weight or more.

  Since the (meth) acrylic adhesive according to the present invention has the above-described configuration, it is excellent in shear adhesive strength at high temperatures.

  Moreover, in the adhesive tape which concerns on this invention, the adhesive layer which is the said (meth) acrylic-type adhesive is laminated | stacked on the surface of the at least one side of a base material. Therefore, when the polishing cloth is fixed to the surface plate using the pressure-sensitive adhesive tape of the present invention, the polishing cloth is difficult to peel off even if the hard material is polished. Therefore, the pressure-sensitive adhesive tape of the present invention is excellent in reliability. In particular, when polishing a hard material, it is necessary to polish at a high speed, polish at a high pressure, or polish for a long time. Therefore, the adhesive tape is exposed to a higher temperature when polishing a hard material. In this invention, since the shear adhesive force at high temperature can be improved, an adhesive tape can be used suitably at the time of grinding | polishing of 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 a hard material having a Vickers hardness of 7 or more and sapphire glass. For example, conventional (meth) acrylic adhesives and adhesive tapes cannot be applied to hard materials with higher Vickers hardness than gorilla glass or sapphire glass, even if applied to gorilla glass polishing. There is. In the present invention, even when a hard element material having a considerably high altitude is used, peeling of the polishing cloth can be sufficiently suppressed during polishing.

[(Meth) acrylic adhesive]
The (meth) acrylic adhesive according to the present invention includes a (meth) acrylic material. The said (meth) acrylic material is a composition which advanced the bridge | crosslinking of the crosslinkable composition containing a (meth) acryl copolymer and a crosslinking agent. The said (meth) acrylic material contains the crosslinked body which the bridge | crosslinking of the said (meth) acryl copolymer advanced with the crosslinking agent. The (meth) acrylic material may contain an unreacted (meth) acrylic copolymer that does not contribute to crosslinking and a crosslinking agent. The degree of progress of crosslinking 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 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 parts by weight or more and 0.3 parts by weight or less. .

  The gel fraction of the (meth) acrylic pressure-sensitive adhesive of the present invention is 53% by weight or more. When the said gel fraction is more than the said minimum, the cohesion force of a (meth) acrylic-type adhesive is raised. From the viewpoint of further increasing 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 (meth) acrylic pressure-sensitive adhesive was collected, and the insoluble content when the collected (meth) acrylic pressure-sensitive adhesive was immersed in ethyl acetate at 23 ° C. for 24 hours was filtered through a 200-mesh wire mesh. . The residue on the wire net is heated and dried at 110 ° C., and the weight W2 (g) of the obtained dry residue is measured. The gel fraction (crosslinking degree) is calculated by the following formula (1).

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

  From the viewpoint of making the adhesive strength and cohesive strength of the (meth) acrylic pressure-sensitive adhesive compatible at a high level and further increasing the shear pressure-sensitive adhesive strength at high temperature, the gel fraction of the (meth) acrylic pressure-sensitive adhesive is 55% by weight. % Or more, preferably 65% by weight or less, and more preferably 62% by weight or less.

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 modulus is equal to or higher than the lower limit, the cohesive force of the (meth) acrylic pressure-sensitive adhesive can be further increased. Moreover, from the viewpoint of further increasing the adhesive strength of the (meth) acrylic adhesive, the shear storage elastic modulus is preferably 10 × 10 ⁴ Pa or less.

  The shear storage 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 conditions of a frequency of 10 Hz and a strain of 0.1%.

From the viewpoint of making the adhesive strength and cohesive strength of the (meth) acrylic pressure-sensitive adhesive compatible at a high level and further increasing the shear pressure-sensitive adhesive strength at high temperatures, the shear storage modulus of the (meth) acrylic pressure-sensitive adhesive is 6 It is preferable that it is x10 ⁴ Pa or more.

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

((Meth) acrylic material)
The said (meth) acrylic material is a composition which advanced the bridge | crosslinking of the crosslinkable composition containing a (meth) acryl copolymer and a crosslinking agent.

(Meth) acrylic copolymers;
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.

  Although it does not specifically limit as said (meth) acrylic acid ester monomer, For example, alkyl, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, etc. (Meth) acrylic acid alkyl ester having 1 to 3 carbon atoms; butyl (meth) acrylate; trimethyl (meth) acrylate, stearyl (meth) acrylate and the like having an alkyl group having 13 to 18 carbon atoms ( Examples include (meth) acrylic acid alkyl esters. The said (meth) acrylic acid ester monomer may be used independently and may use multiple together.

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

  Although it does not specifically limit as said hydroxyl-containing monomer, For example, (meth) acrylic acid hydroxyalkyl, such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate; Examples include (meth) acrylic acid esters having an alcohol and a diethylene glycol group. The above hydroxyl group-containing monomers may be used alone or in combination. From the viewpoint of further increasing the shear adhesive strength of the (meth) acrylic pressure-sensitive adhesive at high temperature, the hydroxyl group-containing monomer is preferably the hydroxyalkyl (meth) acrylate.

  In the mixed monomer, 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 parts by weight or more and 0.3 parts by weight or less. . 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 strength at high temperatures. From the viewpoint of further increasing the shear adhesive strength of the (meth) acrylic pressure-sensitive adhesive at a high temperature, 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 parts by weight or more and 0.2 parts by weight or less is preferable.

  The mixed monomer may contain another polymerizable monomer that can be copolymerized as necessary.

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

  Although the weight average molecular weight (Mw) of the said (meth) acrylic polymer is not specifically limited, Preferably it is 650,000 or more, Preferably it is 1.2 million or less. When the weight average molecular weight (Mw) is not less than the above lower limit and not more than the above upper limit, the adhesive strength and cohesive strength of the (meth) acrylic adhesive can be compatible at a high level, and the shear adhesive strength at high temperature. Can be further increased.

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

  In order to copolymerize the mixed monomer to obtain the (meth) acrylic copolymer, for example, the mixed monomer is subjected to a radical reaction in the presence of a polymerization initiator. A conventionally known method is used as a method for radical reaction of the mixed monomer, that is, a polymerization method. 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, and a bulk polymerization method.

  It does not specifically limit as said polymerization initiator, 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-butylper Examples thereof include oxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. The said polymerization initiator may be used independently and may use 2 or more types together.

Cross-linking agent;
In the (meth) acrylic material, the crosslinking of the (meth) acrylic copolymer is advanced by a crosslinking agent.

  The crosslinking agent is not particularly limited, and for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, a peroxide crosslinking agent, a urea crosslinking agent, a metal alkoxide crosslinking agent, a metal chelate crosslinking agent. Agents, metal salt crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, amine crosslinking agents and the like. The above crosslinking agents may be used alone or in combination.

  From the viewpoint of further increasing the shear adhesive strength of the (meth) acrylic pressure-sensitive adhesive at a high temperature, the cross-linking agent preferably contains the isocyanate-based cross-linking agent.

  Examples of the isocyanate crosslinking 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. , Cycloaliphatic 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, xylylene diisocyanate Polyisocyanate etc. are mentioned. The said isocyanate type crosslinking agent may be used independently and may use multiple together.

  In the crosslinkable composition before the crosslinking proceeds, 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. Part or less. When the content of the crosslinking agent is not less than the above lower limit and not more than the above upper limit, the adhesive strength and cohesive strength of the (meth) acrylic adhesive can be compatible at a high level, and shear adhesive strength at high temperature can be achieved. It can be further increased.

(Tackifying resin)
The (meth) acrylic pressure-sensitive adhesive of the present invention may further contain a tackifier resin. The (meth) acrylic adhesive of the present invention may contain the above (meth) acrylic material and a tackifying resin.

  The tackifying resin is not particularly limited, and examples thereof include petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymers, and alicyclic copolymers. Coumarone-indene resin; terpene resin; terpene phenol resin; rosin resin such as polymerized rosin; phenol resin; xylene resin. These resins may be hydrogenated resins. The tackifying resins may be used alone or in combination.

  From the viewpoint of making the adhesive strength and cohesive strength of the (meth) acrylic adhesive compatible at a high level and further increasing the shear adhesive strength at high temperature, the softening point of the tackifying resin is 110 ° C. or higher. Preferably, it is 130 ° C or higher, more preferably 150 ° C or higher, and preferably 170 ° C or lower.

  Further, the content of the tackifying resin is not particularly limited, but is preferably 30 parts by weight or more, more preferably 35 parts by weight or more, with respect to 100 parts by weight of the (meth) acrylic material. The amount 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 not less than the above lower limit and not more than the above upper limit, the adhesive strength and cohesive strength of the (meth) acrylic adhesive can be compatible at a high level, and shear adhesive strength at high temperature Can be further increased.

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

  The tackifier resin may be used by mixing with the crosslinkable composition before proceeding with the crosslinking of the crosslinkable composition, or (meth) acrylic by proceeding with the crosslinking of the crosslinkable composition. After obtaining the material, it may be used by mixing with the (meth) acrylic material.

[Adhesive tape]
Hereinafter, specific embodiments of the pressure-sensitive 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 substrate 2 has a first surface 2a and a second main surface 2b. The first surface 2a and the second surface 2b are opposed to each other. A 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 pressure-sensitive adhesive tape 1 is a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is provided on both surfaces of a base material 2. In the present invention, the pressure-sensitive adhesive layer may be provided only on one surface of the substrate 2. More specifically, the 1st adhesive layer 3 may be provided only on the 1st surface 2a of the base material 2, and the 2nd adhesive layer 4 is provided only on the 2nd surface 2b. It may be provided.

  Although it does not specifically limit as a material of the base material 2, For example, synthetic resin films, such as a polyester-type resin and a polypropylene-type resin, are mentioned, Especially, it is flat, a thickness fluctuation is small, and it has fixed intensity | strength. Therefore, a polyester resin film can be suitably used.

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

  In the present invention, each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be the above-described (meth) acrylic pressure-sensitive adhesive, and only the first pressure-sensitive adhesive layer is the above-described (meta). ) Acrylic adhesive may be used.

  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, 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-described configuration, and since the pressure-sensitive adhesive layer is the (meth) acrylic pressure-sensitive adhesive of the present invention, it has excellent shear adhesive strength at high temperatures. Therefore, when polishing a hard material using a polishing machine, if the polishing cloth is fixed to a surface plate using the (meth) adhesive tape of the present invention, the polishing cloth is hardly 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 the purpose of fixing a polishing cloth to a surface plate of a polishing machine. In particular, the (meth) acrylic pressure-sensitive adhesive and pressure-sensitive adhesive tape of the present invention are excellent in shear adhesive strength at high temperatures. Therefore, when polishing a hard material having a Vickers hardness of 7 or more, the surface plate of the above polishing machine It can be used more suitably for the purpose of fixing the polishing cloth to the surface. In addition, as a hard material whose said Vickers hardness is 7 or more, a sapphire glass can be used suitably.

  Moreover, when using the adhesive tape of the present invention for the purpose of fixing the polishing cloth to the surface plate of the polishing machine, from the viewpoint of suppressing the peeling of the polishing cloth from the adhesive layer, the surface of the substrate on the polishing cloth side is used. 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)
As a manufacturing method of the adhesive tape of this invention, the following methods are mentioned, for example.

  First, a tackifying resin or the like is added to the (meth) acrylic polymer and the crosslinking agent as necessary, and a solvent is added to prepare a solution of the pressure-sensitive adhesive. This adhesive solution is applied to one surface of the substrate. While removing the solvent in the solution by drying, the crosslinking of the (meth) acrylic polymer proceeds to form the pressure-sensitive adhesive layer. Next, a release film is overlaid on the formed pressure-sensitive adhesive layer so that the release treatment surface faces the pressure-sensitive adhesive layer. As a result, an adhesive tape having a laminate structure of release film / adhesive layer / base material is obtained. In addition, when an adhesive tape is a double-sided adhesive tape, an adhesive tape can be manufactured by forming an adhesive layer on the other side surface of a base material by the same method.

  The solvent for preparing the adhesive solution 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 drying in a drying furnace such as an IR heater or an oven. Drying may be performed under normal pressure or under reduced pressure.

  The shape of the pressure-sensitive adhesive tape of the present invention is not particularly limited, and examples thereof include a rectangle, a circle, an ellipse, 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 a (meth) acrylic adhesive;
In a reactor equipped with a stirrer, a cooler, a thermometer and a nitrogen gas inlet, 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) A reaction solution containing a mixed monomer obtained by mixing 100 parts by weight of ethyl acetate as a solvent was charged, and dissolved oxygen was removed by bubbling with nitrogen gas for 30 minutes.

  Thereafter, the inside of the apparatus was replaced with nitrogen gas, and the temperature of the reaction solution was increased with an oil bath while stirring the reaction solution until the reaction solution reached the reflux temperature. When the reaction solution reaches the reflux temperature, a polymerization initiator solution in which 0.1 part by weight of azobisisobutyronitrile is dissolved in 1.35 parts by weight of cyclohexane is added to the reaction solution over 7 hours. Copolymerized. To the acrylic copolymer solution obtained after completion of the polymerization, 2.9 parts by weight of coronate (manufactured by Nippon Polyurethane Co., Ltd., trade name “L-55”) as a crosslinking agent and terpene phenol resin (manufactured by Yasuhara Chemical Co., Ltd.) as a tackifier resin (Trade name “T160”, softening point 160 ° C.) 40 parts by weight were added and stirred to prepare an adhesive solution.

Production of double-sided adhesive tape;
A polyethylene terephthalate film whose one surface was release-treated was prepared. The pressure-sensitive adhesive solution obtained above was applied to the release surface of the polyethylene terephthalate film so that the thickness after drying was 80 μm, dried at 110 ° C. for 5 minutes, and the acrylic copolymer solution in the acrylic copolymer solution was dried. Crosslinking of the copolymer was advanced to produce a laminated sheet having an adhesive layer on the release treated surface of the polyethylene terephthalate film. Another one of the above laminated sheets was produced in the same manner to obtain a total of two of the above laminated sheets.

  Next, a polyethylene terephthalate film (thickness: 23 μm) was prepared as a substrate. One of the 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 laminated and integrated. The other laminated sheet was laminated on the surface of the other side of the substrate from the pressure-sensitive adhesive layer surface, and the pressure-sensitive adhesive layer was transferred to the substrate and laminated and integrated. Thereby, a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer having a thickness of 80 μm was provided on both surfaces of the substrate was obtained.

(Examples 2-6 and Comparative Examples 1-4)
A monomer is selected from butyl acrylate (BA), acrylic acid (AAc), 2-ethylhexyl acrylate (2EHA), 2-hydroxyethyl acrylate (HEA), vinyl acetate (VAc) and methyl methacrylate (MMA). In the same manner as in Example 1, except that the mixed monomer mixed at the mixing ratio shown in Table 1 below was used, and that the gel fraction was set as shown in Table 1 below by adjusting the drying conditions. Thus, a double-sided adhesive tape was obtained.

(Example 7)
The polymerized rosin ester (trade name “D160”, softening point 160 ° C., manufactured by Arakawa Chemical Industries, Ltd.) was used as the tackifier resin, and the gel fraction was set as shown in Table 1 by adjusting the drying conditions. Except having done, it carried out similarly to Example 1, and obtained the double-sided adhesive tape.

(Example 8)
Table 1 below shows terpene phenols (trade name “T160”, softening point 160 ° C.) and polymerized rosin ester (trade name “D160”, softening point 160 ° C., manufactured by Arakawa Chemical Industries, Ltd.) as tackifying resins. A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the mixture was used at the indicated mixing ratio and that the drying conditions were adjusted and the gel fraction was set as shown in Table 1 below.

Example 9
Other than using Nikanol (trade name “HP120”, softening point 120 ° C., manufactured by Fudou Chemical Co., Ltd.) as the tackifying resin, and adjusting the drying conditions to set the gel fraction as shown in Table 1 below. Obtained a double-sided pressure-sensitive adhesive tape in the same manner as in Example 1.

<Evaluation>
(Meth) acrylic pressure-sensitive adhesive (pressure-sensitive adhesive layer) constituting the double-sided pressure-sensitive adhesive tapes and double-sided pressure-sensitive adhesive tapes obtained in Examples 1 to 9 and Comparative Examples 1 to 4 and (meth) acrylic pressure-sensitive adhesives (Meta ) The following evaluation was performed on the acrylic copolymer. The results are shown in Table 1 below.

(1) Molecular weight of (meth) acrylic copolymer About the (meth) acrylic copolymer before cross-linking used for producing the double-sided pressure-sensitive adhesive tape, a column (product name “LF-804” manufactured by Showa Denko KK) is used. Analysis by gel permeation chromatography (GPC) was performed, and polystyrene conversion was performed 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 (product number “DVA-310” manufactured by IT Measurement Control Co., Ltd.), in a solid shear mode, a frequency of 10 Hz, a strain of 0.1%, a temperature of −40 ° C. to 140 ° C., and a temperature increase It is a peak value of tan δ by measuring dynamic viscoelasticity of a (meth) acrylic pressure-sensitive adhesive (pressure-sensitive adhesive layer) test piece (thickness 1.2 mm, length 11 mm × width 6 mm) under the condition of a speed of 3 ° C./min. Tg was measured.

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

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

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

(5) Holding power FIG. 2 is a schematic diagram for explaining a holding power test method. As shown in FIG. 2, the test piece 5 and the first SUS plate 7 are bonded together 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. The distance of the deviation after 1 hour and 24 hours was measured at a temperature of 100 ° C.

(6) High-temperature shear adhesive strength Double-sided adhesive tape cut out to 10 × 10 mm is sandwiched between two aluminum plates, and then crimped for 20 minutes at a pressure of ² kg / cm ² , and further at 40 ° C. and 0.3 MPa. Two aluminum plates were attached by pressure bonding using an autoclave (manufactured by Hirayama Seisakusho, 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 strength was measured at a rate of 200 mm / min in an atmosphere at 80 ° C. More specifically, as shown in FIG. 3, both ends of the first and second aluminum plates 9 and 10 bonded together by the double-sided adhesive tape 6 are pulled in the direction of the arrow shown in FIG. The maximum load was measured.

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

(8) Polishing machine evaluation The thing which stuck the double-sided adhesive tape obtained in Examples 1-9 and Comparative Examples 1-4 on the surface of a sapphire board of thickness 500 micrometers and a 6-inch diameter was used as a workpiece | work. The double-sided adhesive tape surface side of the sapphire substrate, which is a workpiece, is vacuum-adsorbed to the suction head of the polishing apparatus, and then the suction head is rotated and lowered at 100 rpm and the sapphire surface is slid on the polishing surface plate rotating at 120 rpm The polishing process was started while applying a pressure of 120 g / cm ² , and the polishing process was terminated when the machining allowance was 12 μm. During the polishing process, a 0.5 to 1.5 μm diameter diamond abrasive dispersed abrasive slurry was supplied onto the polishing surface plate. After 100 hours of these operations, the state of the polishing cloth adhered on the polishing surface plate was observed and evaluated according to the following evaluation criteria.

[Criteria for polishing machine evaluation]
○: Even after polishing for 100 hours, neither peeling nor floating is observed.
Δ: Before polishing for 100 hours, slight peeling or floating was observed to such an extent that polishing could be continued.
X: Peeling or floating was observed before 100 hours had passed after polishing.

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

Claims (3)

Including a (meth) acrylic material that has been crosslinked by a crosslinkable composition comprising a (meth) acrylic copolymer and a crosslinking agent;
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 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 0.3 part by weight or less. ,
A (meth) acrylic pressure-sensitive adhesive having a gel fraction of 53% by weight or more. The (meth) acrylic pressure-sensitive adhesive according to claim 1, wherein 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.   The (meth) acrylic adhesive according to claim 1 or 2, wherein the hydroxyl group-containing monomer is hydroxyalkyl (meth) acrylate.

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