JP7490399B2 - Removable adhesive tape - Google Patents

Description

The present invention relates to a removable adhesive tape.

In recent years, as wafers become thinner, adhesive tapes are being used as support materials in various semiconductor manufacturing processes. In semiconductor manufacturing processes, the properties required for each step are different, and therefore the materials used for adhesives and substrates are becoming more diverse. As a result, sufficient anchoring strength between the substrate and adhesive may not be ensured. As a method for improving anchoring strength to the substrate, it has been proposed to form an undercoat layer on the substrate (e.g., Patent Documents 1 to 3). However, there are problems in that sufficient anchoring strength cannot be ensured and that the undercoat layer itself cannot be formed.

In addition, because they are easy to remove, adhesive tapes using active energy ray-curable adhesives have been proposed. When active energy ray-curable adhesives are irradiated with active energy rays, the double bonds of the materials contained in the adhesive cure and shrink. In particular, adhesives using polymers with double bonds introduced into the side chains tend to have poor anchoring properties to the substrate because the polymer itself cures and shrinks, and adhesive residue may be left on the adherend when peeled off. In particular, when the side chain of the polymer has a substituent with a long carbon chain, there is a problem of even poorer anchoring properties.

JP 2005-231119 A JP 2009-224375 A JP 2012-214585 A

The present invention was made to solve the above-mentioned problems of the conventional technology, and its purpose is to provide a removable adhesive tape with excellent anchoring strength between the adhesive layer and the substrate.

The removable adhesive tape of the present invention comprises, in this order, a substrate, an undercoat layer containing a binder resin and a filler, and an adhesive layer, wherein at least a part of the filler has a protrusion protruding from the undercoat layer into the adhesive layer, and the interface between the undercoat layer and the adhesive layer has an uneven surface.
In one embodiment, the filler is at least one selected from the group consisting of silica, aluminum oxide, and calcium carbonate.
In one embodiment, the binder resin is a urethane-based resin.
In one embodiment, the pressure-sensitive adhesive layer contains an active energy ray-curable pressure-sensitive adhesive.
In one embodiment, the base polymer of the active energy ray-curable pressure-sensitive adhesive is an acrylic resin having a side chain double bond introduced therein.
In one embodiment, 50% or more of the side chains of the acrylic resin having a double bond introduced into the side chain are substituents having 8 or more carbon atoms.
In one embodiment, the pressure-sensitive adhesive layer further contains an isocyanate-based crosslinking agent.
In one embodiment, the height of the protrusion is 1 μm or more.
In one embodiment, the number of the protrusions is 10 or more per mm.
In one embodiment, the average particle size of the filler is 0.2 μm to 2.0 μm.
In one embodiment, the adhesive layer has an anchoring strength of 2 N/50 mm or more.
In one embodiment, the substrate contains at least one resin selected from the group consisting of polyethylene terephthalate-based resins, polyethylene naphthalate-based resins, and polyolefin-based resins.
In one embodiment, the removable adhesive tape is used in semiconductor processing applications.

According to the present invention, it is possible to provide a removable adhesive tape that has excellent anchoring power between the adhesive layer and the substrate. In the removable adhesive tape of the present invention, at least a part of the filler has a protrusion that protrudes from the undercoat layer into the adhesive layer, and the interface between the undercoat layer and the adhesive layer has unevenness. As a result, the surface area of contact between the undercoat layer and the adhesive layer is increased, and the affinity between the functional group of the adhesive contained in the adhesive layer and the filler can be improved. Furthermore, the reactivity with the crosslinking agent at the interface between the undercoat layer and the adhesive layer can also be improved. As a result, the anchoring power can be improved. Therefore, even when an adhesive containing a side chain double bond-introduced polymer is used, it is possible to prevent adhesive residue on the adherend.

1 is a schematic cross-sectional view of a removable adhesive tape according to one embodiment of the present invention. 2A, 2B, and 2C are SEM photographs of cross sections of a removable adhesive tape according to an embodiment of the present invention, taken at a magnification of 2000x, 5000x, and 10000x, respectively. FIG. 2 is a schematic diagram illustrating a method for measuring the height of a protrusion in the removable adhesive tape of the present invention.

A. Overall configuration of removable adhesive tape FIG. 1 is a schematic cross-sectional view of a removable adhesive tape according to one embodiment of the present invention. The removable adhesive tape 100 of the present invention comprises a substrate 10, an undercoat layer 20 containing a binder resin and a filler, and an adhesive layer 30, in this order. The removable adhesive tape 100 has a protruding portion 40 in which at least a part of the filler protrudes from the undercoat layer 20 to the adhesive layer 30, due to the undercoat layer containing a filler. Due to this protruding portion 40, the interface between the undercoat layer 20 and the adhesive layer 30 has unevenness. Therefore, the surface area in contact between the undercoat layer 20 and the adhesive layer 30 is increased, and the reactivity at the interface between the undercoat layer and the adhesive layer can be improved. As a result, the anchoring force can be improved.

2 is a SEM photograph of a cross section of a removable adhesive tape in one embodiment of the present invention. FIG. 2(a) is a photograph taken at a magnification of 2000 times, FIG. 2(b) is a photograph taken at a magnification of 5000 times, and FIG. 2(c) is a photograph taken at a magnification of 10000 times. In the SEM photographs taken at all magnifications, it can be confirmed that the filler contained in the undercoat layer has a protrusion protruding into the adhesive layer. In one embodiment, a filler having a wide particle size distribution is used as the filler. By using such a filler, unevenness can also occur between the fillers. Therefore, many protrusions can be formed at the interface between the adhesive layer and the undercoat layer (for example, FIG. 2(a) and FIG. 2(b)). In addition, it can be confirmed that fine unevenness is also formed at the interface between the undercoat layer and the adhesive layer by including a filler with a smaller particle size (for example, FIG. 2(c)).

The height of the protrusion is preferably 1 μm or more, more preferably 1.2 μm or more, and even more preferably 1.5 μm or more. When the height of the protrusion is in the above range, the surface area of contact between the undercoat layer and the adhesive layer is increased, and the anchoring property can be improved. The height of the protrusion may be adjusted to a value that matches the thickness of the undercoat layer and the adhesive layer and prevents dents on the substrate when the removable adhesive tape is rolled, and is, for example, 5.0 μm or less. In this specification, the height of the protrusion refers to the distance between the part where the interface between the undercoat layer and the adhesive layer is flat and the highest part of the filler. The height of the protrusion can be measured by any appropriate method. For example, the removable adhesive tape can be cut by any appropriate method to prepare a cross section, and the cross section can be observed by a scanning electron microscope.

The removable adhesive tape preferably has 10 or more protrusions per mm in the cross section, more preferably 15 or more protrusions per mm, and even more preferably 20 or more protrusions per mm. The above range of protrusions can improve the anchoring properties of the removable adhesive tape. The more protrusions there are, the more preferable, for example, 150 or less protrusions per mm. In this specification, the number of protrusions refers to the number of protrusions per length of a cross section prepared by cutting using any suitable method. The number of protrusions can be measured using any suitable method. In this specification, the removable adhesive tape is cut using any suitable method to prepare a cross section, the number of protrusions within a range of 250 μm is measured at three random points on the cross section, and the average of the numbers at the three points is converted to mm, which is referred to as the number of protrusions.

The thickness of the removable adhesive tape can be set to any appropriate value depending on the application to which it is to be used. The thickness of the removable adhesive tape is preferably 25 μm to 800 μm, more preferably 30 μm to 600 μm, and even more preferably 30 μm to 450 μm.

B. Adhesive Layer Any suitable adhesive can be used as the adhesive composition forming the adhesive layer. The removable adhesive tape of the present invention has excellent anchoring power. Therefore, even an adhesive with high adhesive power can be suitably used.

In one embodiment, the adhesive layer contains an active energy ray curable adhesive. The active energy ray curable adhesive has low elasticity and high flexibility when applied, and is easy to handle and has excellent adhesive properties. On the other hand, in situations where peeling is required, the adhesive strength is reduced by irradiation with active energy rays, resulting in a removable adhesive tape that can be easily peeled off. In addition, the active energy ray curable adhesive has a problem that the double bond cures and shrinks, resulting in poor anchoring to the substrate and leaving adhesive residue on the adherend when peeled off. The removable adhesive tape of the present invention can exhibit excellent anchoring strength even when the adhesive layer contains an active energy ray curable adhesive. Examples of active energy rays include gamma rays, ultraviolet rays, visible light, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flow, ionizing rays, particle beams, etc. UV rays are preferred.

Any suitable adhesive can be used as the active energy ray curable adhesive. For example, it may be an adhesive in which an ultraviolet-curable monomer and/or oligomer is added to any suitable adhesive such as an acrylic adhesive, a rubber adhesive, a silicone acrylic adhesive, or a polyvinyl ether adhesive, or it may be an adhesive using a polymer having a carbon-carbon double bond in the side chain (hereinafter also referred to as a side chain double bond-introduced polymer) as the base polymer.

As the ultraviolet-curable monomer and oligomer, any suitable monomer or oligomer can be used. Examples of the ultraviolet-curable monomer include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Examples of the radiation-curable oligomer include urethane-based oligomers, polyether-based oligomers, polyester-based oligomers, polycarbonate-based oligomers, and polybutadiene-based oligomers. As the oligomer, those having a molecular weight of about 100 to 30,000 are preferably used. Only one type of monomer and oligomer may be used, or two or more types may be used in combination.

The monomer and/or oligomer may be used in any appropriate amount depending on the type of adhesive used. For example, it is preferably used in an amount of 5 to 500 parts by weight, more preferably 40 to 150 parts by weight, per 100 parts by weight of the base polymer constituting the adhesive.

In one embodiment, the adhesive layer preferably contains an active energy ray curable adhesive containing a side chain double bond-introduced polymer. In an active energy ray curable adhesive containing a side chain double bond-introduced polymer, the polymer itself undergoes cure shrinkage, so anchoring to the substrate is more required. By having the above-mentioned removable adhesive tape have protruding portions, it is possible to prevent adhesive residue on the adherend, even when an active energy ray curable adhesive containing a side chain double bond-introduced polymer is used.

When using an adhesive containing a side-chain double bond-introduced polymer, a polymer having a polymerizable carbon-carbon double bond in the side chain and having adhesive properties is used as the base polymer. Examples of such polymers include polymers in which a polymerizable carbon-carbon double bond has been introduced into a resin such as a (meth)acrylic resin, a vinyl alkyl ether resin, a silicone acrylic resin, a polyester resin, a polyamide resin, a urethane resin, or a styrene-diene block copolymer. Preferably, a (meth)acrylic resin in which a polymerizable carbon-carbon double bond has been introduced into a (meth)acrylic resin (hereinafter also referred to as a side-chain double bond-introduced acrylic resin) is used. By using such a (meth)acrylic polymer, it is easy to adjust the storage modulus and tensile modulus of the adhesive layer, and an adhesive tape with an excellent balance between adhesive strength and peelability can be obtained. In addition, "(meth)acrylic" refers to acrylic and/or methacrylic.

Any suitable (meth)acrylic resin can be used as the (meth)acrylic resin. Examples of (meth)acrylic resins include polymers obtained by polymerizing a monomer composition containing one or more esters of acrylic acid or methacrylic acid having a linear or branched alkyl group.

The linear or branched alkyl group is preferably an alkyl group having 30 or less carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, and even more preferably an alkyl group having 4 to 18 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, octyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl, and dodecyl groups.

In one embodiment, the side chain double bond-introduced acrylic resin preferably has 50 mol % or more of the side chains with a substituent having 8 or more carbon atoms. An acrylic resin having a long-chain substituent having 8 or more carbon atoms in the side chain can prevent adhesive residue on the adherend. On the other hand, an acrylic resin having a long-chain substituent having 8 or more carbon atoms in the side chain can have a problem with anchoring to the substrate. According to the present invention, even if 50 mol % or more of the side chains are long-chain substituents having 8 or more carbon atoms, the substrate and the adhesive layer can have excellent anchoring properties. Therefore, both anchoring properties between the substrate and the adhesive layer and prevention of adhesive residue on the adherend can be achieved. More preferably, the side chain double bond-introduced acrylic resin has 60 mol % or more of the side chains with a substituent having 8 or more carbon atoms, and even more preferably, the side chain double bond-introduced acrylic resin has 70 mol % or more of the side chains with a substituent having 8 or more carbon atoms.

The monomer composition forming the (meth)acrylic resin may contain any suitable other monomer. Examples of other monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and 4-hydroxyethyl (meth)acrylate. Examples of the monomers include hydroxyl group-containing monomers such as hydroxymethylcyclohexyl)-methyl acrylate, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and functional group-containing monomers such as phosphate group-containing monomers such as 2-hydroxyethylacryloylphosphate. By including a functional group-containing monomer, a (meth)acrylic resin in which a polymerizable carbon-carbon double bond is easily introduced can be obtained. The content of the functional group-containing monomer is preferably 4 to 30 parts by weight, more preferably 6 to 20 parts by weight, based on 100 parts by weight of the total monomers in the monomer composition.

As the other monomer, a polyfunctional monomer may be used. By using a polyfunctional monomer, the cohesive strength, heat resistance, adhesiveness, etc. of the adhesive can be increased. In addition, since the amount of low molecular weight components in the adhesive layer is reduced, an adhesive tape that is less likely to contaminate the adherend can be obtained. Examples of polyfunctional monomers include hexanediol (meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and urethane (meth)acrylate. The content ratio of the polyfunctional monomer is preferably 1 part by weight to 100 parts by weight, more preferably 5 parts by weight to 50 parts by weight, based on 100 parts by weight of the total monomers in the monomer composition.

The weight average molecular weight of the (meth)acrylic resin is preferably 300,000 or more, more preferably 500,000 or more, and even more preferably 800,000 to 3,000,000. Within such a range, bleeding of low molecular weight components can be prevented, and a low-staining adhesive tape can be obtained. The molecular weight distribution (weight average molecular weight/number average molecular weight) of the (meth)acrylic resin is preferably 1 to 20, and more preferably 3 to 10. By using a (meth)acrylic resin with a narrow molecular weight distribution, bleeding of low molecular weight components can be prevented, and a low-staining adhesive tape can be obtained. The weight average molecular weight and number average molecular weight can be determined by gel permeation chromatography measurement (solvent: tetrahydrofuran, polystyrene equivalent).

A polymer having a polymerizable carbon-carbon double bond in a side chain can be obtained by any suitable method. For example, it can be obtained by reacting (e.g., condensation reaction, addition reaction) a resin obtained by any suitable polymerization method with a compound having a polymerizable carbon-carbon double bond. Specifically, when a (meth)acrylic resin is used, the polymer can be obtained by polymerizing a (meth)acrylic resin (copolymer) having a structural unit derived from a monomer having any suitable functional group in any suitable solvent, and then reacting the functional group of the acrylic resin with a compound having a polymerizable carbon-carbon double bond that can react with the functional group. The amount of the compound having a polymerizable carbon-carbon double bond to be reacted is preferably 4 to 30 parts by weight, more preferably 4 to 20 parts by weight, relative to 100 parts by weight of the resin. Any suitable solvent can be used as the solvent, and examples of such solvents include various organic solvents such as ethyl acetate, methyl ketone, and toluene.

When reacting a resin with a compound having a polymerizable carbon-carbon double bond as described above, it is preferable that the resin and the compound having a polymerizable carbon-carbon double bond each have a functional group capable of reacting with each other. Examples of functional group combinations include a carboxyl group/epoxy group, a carboxyl group/aziridine group, and a hydroxyl group/isocyanate group. Among these functional group combinations, the combination of a hydroxyl group and an isocyanate group is preferable because of the ease of tracking the reaction.

Examples of the compound having a polymerizable carbon-carbon double bond include 2-isocyanatoethyl methacrylate, methacryloisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc.

B-1. Additives The active energy ray-curable pressure-sensitive adhesive may contain any suitable additive as necessary. Examples of the additives include photopolymerization initiators, crosslinking agents, catalysts (e.g., platinum catalysts), tackifiers, plasticizers, pigments, dyes, fillers, antioxidants, conductive materials, UV absorbers, light stabilizers, release regulators, softeners, surfactants, flame retardants, solvents, etc.

In one embodiment, the active energy ray-curable adhesive preferably contains a photopolymerization initiator. Any suitable initiator can be used as the photopolymerization initiator.

The photopolymerization initiator may be used in any appropriate amount. The content of the photopolymerization initiator is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 7 parts by weight, relative to 100 parts by weight of the ultraviolet-curable adhesive. If the content of the photopolymerization initiator is less than 0.1 parts by weight, there is a risk that the adhesive will not cure sufficiently when irradiated with active energy rays. If the content of the photopolymerization initiator is more than 10 parts by weight, there is a risk that the storage stability of the adhesive will decrease, and precipitation on the surface of the adhesive layer and outgassing will increase.

In one embodiment, the active energy ray curable adhesive further contains a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, chelate-based crosslinking agents, and melamine-based crosslinking agents. The content of the crosslinking agent is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 7 parts by weight, and even more preferably 0.025 to 5 parts by weight, relative to 100 parts by weight of the base polymer contained in the active energy ray curable adhesive. The flexibility of the adhesive layer can be controlled by the content of the crosslinking agent. If the content of the crosslinking agent is less than 0.01 parts by weight, the adhesive may become a sol, and the adhesive layer may not be formed. If the content of the crosslinking agent is more than 10 parts by weight, the adhesion to the adherend may decrease, and the adherend may not be sufficiently protected.

In one embodiment, an isocyanate-based crosslinking agent is preferably used. Isocyanate-based crosslinking agents are preferred because they can react with a wide variety of functional groups. Particularly preferably, a crosslinking agent having three or more isocyanate groups is used. By using an isocyanate-based crosslinking agent as the crosslinking agent and setting the content of the crosslinking agent within the above range, a pressure-sensitive adhesive layer can be formed that has excellent peelability and significantly less adhesive residue even after heating.

The thickness of the adhesive layer can be set to any appropriate value. The thickness of the adhesive layer is preferably 4 μm to 500 μm, more preferably 5 μm to 400 μm, and even more preferably 5 μm to 330 μm. By having the thickness of the adhesive layer within the above range, it is possible to exhibit sufficient adhesion to the adherend, and to exhibit sufficient embedding of bumps and embedding into unevenness.

The anchoring force of the adhesive layer (adhesion of the adhesive layer to the substrate) is preferably 2 N/50 mm or more, more preferably 3 N/50 mm or more, and even more preferably 5 N/50 mm or more. The higher the anchoring force of the adhesive layer, the better. In this specification, the anchoring force of the adhesive layer refers to the peeling force (anchor force) when the adhesive layer is irradiated with active energy rays to harden the adhesive layer, an adhesive tape is attached to the hardened adhesive layer, and the layer is peeled off at a tensile speed of 300 mm/min using a T-type peel. When this measurement method is used, the anchoring force may be low if the adhesive layer contains a large amount of release agent.

C. Undercoat layer The undercoat layer contains a binder resin and a filler. The undercoat layer contains the filler, and thus at least a part of the filler has a protrusion protruding from the undercoat layer into the pressure-sensitive adhesive layer. The presence of this protrusion increases the surface area of contact between the undercoat layer and the pressure-sensitive adhesive layer, and as a result, the anchoring force can be improved.

C-1. Binder resin Any suitable resin can be used as the binder resin. Examples include urethane resin, polyester resin, and acrylic resin. Preferably, urethane resin is used. Specific examples of urethane resin include polyacrylic urethane, polyester urethane, or precursors thereof. This is because coating and application to a substrate is simple, and a wide variety of resins can be selected industrially and are inexpensively available. The urethane polymer is, for example, a polymer consisting of a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl group-containing monomer (e.g., a hydroxyl group-containing acrylic compound or a hydroxyl group-containing ester compound). The binder resin may or may not contain a structure derived from an aromatic compound in the molecule.

C-2. Filler Any suitable filler can be used as the filler. Examples include metal oxides such as silica, alumina, calcium carbonate, titanium oxide, magnesium oxide, and zinc oxide, and talc. Preferably, at least one selected from the group consisting of silica, alumina, and calcium carbonate is used. These fillers have hydroxyl groups on the surface, so they have a higher affinity with the functional groups contained in the adhesive, and when an isocyanate-based crosslinking agent is used, they also have good reactivity with the isocyanate-based crosslinking agent, so the anchoring force can be further improved. Only one type of filler may be used, or two or more types may be used in combination.

The average particle size of the filler is preferably 0.2 μm to 2.0 μm, more preferably 0.2 μm to 1.5 μm, and even more preferably 0.2 μm to 1.2 μm. By having the average particle size within the above range, it is possible to prevent the occurrence of dents on the substrate film caused by the opposite surface of the undercoat layer when the removable adhesive tape is rolled.

In one embodiment, the wider the particle size distribution of the filler, the more preferable. By using a filler with a wide particle size distribution, particles with a particle size substantially larger than the average particle size are also included, and the height of the protrusions can be made sufficiently high. In addition, as the variation in particle size between fillers increases, steps are also generated between the fillers, resulting in increased unevenness at the interface between the adhesive layer and the undercoat layer, and the contact surface area can be increased. As a result, the anchoring property can be further improved. Any appropriate method can be used as a method for widening the particle size distribution of the filler. For example, a filler with a large variation in particle size may be used, or two or more fillers with different particle sizes may be mixed and used.

As the filler, for example, a filler having a particle size distribution of 0.01 μm to 10 μm in particle size can be used, preferably a filler having a particle size distribution of 0.05 μm to 7 μm in particle size can be used, and more preferably a filler having a particle size distribution of 0.08 μm to 5 μm in particle size can be used. The particle size distribution of the filler can be measured by any appropriate method. For example, image analysis, the Coulter method, the stretching sedimentation method, the laser diffraction scattering method, etc. can be used.

Fillers of any suitable shape can be used. Examples include spherical, flat, random, and the like. From the viewpoint of improving the stability of the undercoat layer-forming composition, spherical fillers are preferably used. Fillers of one shape may be used alone, or two or more shapes may be used in combination.

The filler content is preferably 10 to 65 parts by weight, more preferably 12 to 60 parts by weight, and even more preferably 15 to 60 parts by weight, per 100 parts by weight of the binder resin. By keeping the filler content within the above range, the anchoring properties can be improved.

The undercoat layer can be formed by any suitable method. For example, the undercoat layer can be formed by applying an undercoat layer-forming composition containing a binder resin and a filler to a substrate. In addition to the binder resin and the filler, the undercoat layer-forming composition may further contain any suitable additives, such as a crosslinking agent.

The thickness of the undercoat layer may be set to any appropriate value. The thickness of the undercoat layer is preferably 1.0 μm to 4.0 μm, more preferably 1.2 μm to 3.0 μm, and even more preferably 1.5 μm to 2.5 μm. The undercoat layer may be a single layer or two or more layers. When it is two or more layers, it is sufficient that at least the layer in contact with the pressure-sensitive adhesive layer contains a binder resin and a filler, and the other layers may be formed only of a binder resin.

D. Substrate The substrate may be made of any suitable resin. Examples of the resin include polyolefins such as low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, and polymethylpentene, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester (random, alternating) copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, polyurethanes, polyesters such as polyethylene naphthalate, polyimides, polyether ketones, polystyrenes, polyvinyl chlorides, polyvinylidene chlorides, fluororesins, silicone resins, cellulose-based resins, and crosslinked products thereof. Preferably, at least one resin selected from the group consisting of polyethylene terephthalate-based resins, polyethylene naphthalate-based resins, and polyolefin-based resins is used. By using these resins, the anchoring property can be further improved.

The thickness of the substrate is preferably 12 μm to 210 μm, more preferably 17.5 μm to 150 μm, and even more preferably 25 μm to 100 μm. Within this range, a removable adhesive tape having appropriate rigidity, easy application, and excellent handling properties can be obtained.

The surface of the substrate may be subjected to any surface treatment to improve adhesion to the undercoat layer, retention, etc. Examples of the surface treatment include chemical or physical treatments such as corona treatment and plasma treatment, and coating treatment.

E. Manufacturing method of releasable adhesive tape The releasable adhesive tape can be manufactured by any suitable method. For example, it can be obtained by applying an adhesive solution (active energy ray curable adhesive) to a separator, drying it to form an adhesive layer on the separator, and then laminating it to a substrate on which an undercoat layer is formed. In addition, the adhesive solution may be applied to a substrate on which an undercoat layer is formed, and then dried to obtain a releasable adhesive tape. As a method for applying the adhesive solution, various methods such as bar coater application, air knife application, gravure application, gravure reverse application, reverse roll application, lip application, die application, dip application, offset printing, flexographic printing, and screen printing can be adopted. As a drying method, any suitable method can be adopted. In one embodiment, the adhesive layer can be formed through any suitable curing treatment.

The undercoat layer can be formed by any suitable method. For example, it can be formed by applying an undercoat layer-forming composition containing a binder resin and a filler to the substrate and drying it. The application method can be the same as that used to form the pressure-sensitive adhesive layer by application.

F. Uses The removable adhesive tape can be used for any suitable use. For example, it can be used in the processing of semiconductors and LEDs. In one embodiment, the removable adhesive tape can be suitably used for semiconductor processing. Specifically, it can be suitably used as a dicing tape, a back grinding tape, a masking tape, etc.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are by weight unless otherwise specified.

[Production Example 1] Preparation of Side Chain Double Bond-Introduced Acrylic Polymer 1 Acrylic polymer 1 was obtained by addition reaction of 12 parts of 2-methacryloyloxyethyl isocyanate (MOI) to a copolymer prepared by polymerization using 100 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of 2-hydroxyethyl acrylate (HEA), and 25 parts of acryloylmorpholine (ACMO).

[Production Example 2] Preparation of acrylic polymer 2 having a double bond introduced into a side chain Acrylic polymer 2 was obtained by addition reaction of 40 parts of MOI with a copolymer obtained by polymerizing 100 parts of ethyl acrylate (EA), 100 parts of butyl acrylate (BA), and 40 parts of HEA.

[Production Example 3] Preparation of Side Chain Double Bond-Introduced Acrylic Polymer 3 Acrylic Polymer 3 was obtained by addition reaction of 12 parts of 2-methacryloyloxyethyl isocyanate (MOI) with a copolymer obtained by polymerizing 88.8 parts of 2-ethylhexyl acrylate (2EHA) and 11.2 parts of 2-hydroxyethyl acrylate (HEA).

[Example 1]
100 parts by weight of acrylic polymer 1, 3 parts by weight of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name: Coroneto L), and 7 parts by weight of a photopolymerization initiator (manufactured by IGM Resins B.V., product name: Omnirad 651) were mixed to obtain a pressure-sensitive adhesive layer-forming composition 1.
A two-component urethane ink containing no aromatic dicarboxylic acid component was gravure printed to a thickness of 1 μm on a corona-treated substrate (polyethylene naphthalate film, thickness 25 μm, manufactured by Teijin Limited, product name: Teonex Q51C). Next, 100 parts by weight of a polyester urethane resin containing no aromatic dicarboxylic acid component was mixed with 60 parts by weight of alumina (manufactured by Admatechs Co., Ltd., product name: Admafine AO-502, average particle size: 0.2 μm to 0.3 μm) to prepare a filler-containing undercoat layer-forming composition 1. The obtained filler-containing undercoat layer-forming composition 1 was applied to a thickness of 2 μm to form a filler-containing undercoat layer.
Separately, the pressure-sensitive adhesive layer-forming composition 1 was applied to a polyethylene terephthalate separator having a thickness of 38 μm to a thickness of 20 μm. Next, the pressure-sensitive adhesive layer was attached to the filler-containing undercoat layer to transfer the pressure-sensitive adhesive layer, thereby obtaining a removable pressure-sensitive adhesive tape.

[Example 2]
A removable adhesive tape was obtained in the same manner as in Example 1, except that a 150 μm-thick polyolefin film (manufactured by Achilles Corporation, trade name: POVIC) was used as the substrate.

[Example 3]
A pressure-sensitive adhesive layer-forming composition 2 was obtained in the same manner as in Example 1, except that acrylic polymer 2 was used.
A removable adhesive tape was prepared in the same manner as in Example 1, except that the pressure-sensitive adhesive layer-forming composition 2 was used and a 100 μm-thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name: Lumirror ES-10) was used as the substrate.

[Example 4]
A pressure-sensitive adhesive layer-forming composition 3 was obtained in the same manner as in Example 1, except that acrylic polymer 3 was used.
A removable adhesive tape was obtained in the same manner as in Example 1, except that the obtained adhesive layer-forming composition 3 was used.

[Example 5]
16 parts by weight of silica (manufactured by Admatechs Co., Ltd., product name: ADMAFINE SO-C4, average particle size: 0.9 μm to 1.2 μm) was mixed with 100 parts by weight of a polyester urethane resin containing no aromatic dicarboxylic acid component to prepare a filler-containing undercoat layer-forming composition 2. A removable adhesive tape was obtained in the same manner as in Example 1, except that the obtained filler-containing undercoat layer-forming composition 2 was used and that the polyethylene terephthalate film used in Example 3 was used as the substrate.

[Example 6]
A removable adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer-forming composition 3 and the filler-containing undercoat layer-forming composition 2 were used.

[Example 7]
A removable adhesive tape was obtained in the same manner as in Example 1, except that adhesive layer-forming composition 2 was used, filler-containing undercoat layer-forming composition 2 was used, and the polyethylene naphthalate film used in Example 3 was used as the substrate.

[Example 8]
A removable adhesive tape was obtained in the same manner as in Example 1, except that adhesive layer-forming composition 2 was used, filler-containing undercoat layer-forming composition 2 was used, and the polyolefin film used in Example 2 was used as the substrate.

[Example 9]
A pressure-sensitive adhesive layer-forming composition 4 was obtained by mixing 100 parts by weight of an acrylic copolymer as a base polymer (monomer composition ratio: BA 100 parts, EA 30 parts, acrylic acid 100 parts, HEA 1 part), 80 parts by weight of a polyfunctional oligomer (urethane acrylate, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name: UV-1700TL), 3 parts by weight of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name: Coroneto L), and 7 parts by weight of a photopolymerization initiator (manufactured by IGM Resins B.V., product name: omnirad651).
A removable adhesive tape was obtained in the same manner as in Example 1, except that the obtained adhesive layer-forming composition 4 was used.

[Example 10]
A removable adhesive tape was obtained in the same manner as in Example 1, except that adhesive layer-forming composition 4 was used, the polyethylene terephthalate film used in Example 3 was used as the substrate, and undercoat layer-forming composition 2 was used.

[Example 11]
A removable adhesive tape was obtained in the same manner as in Example 1, except that the polyolefin film used in Example 2 was used as the substrate.

(Comparative Example 1)
A two-component urethane ink containing no aromatic dicarboxylic acid component was gravure printed to a thickness of 1 μm on a substrate (a 100 μm-thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name: Lumirror ES-10)). Next, a polyester urethane resin containing no aromatic dicarboxylic acid component was applied to a thickness of 2 μm to form an undercoat layer. A removable adhesive tape was obtained in the same manner as in Example 1.

(Comparative Example 2)
A removable adhesive tape was obtained in the same manner as in Example 1, except that no undercoat layer was formed and the adhesive layer was transferred to the corona-treated surface of the substrate.

<Evaluation>
The removable adhesive tapes obtained in the Examples and Comparative Examples were subjected to the following evaluations. The results are shown in Table 1.

1. Height of protrusions and number of fillers A cross section was prepared for each of the removable adhesive tapes obtained in the examples and comparative examples using an ion polishing device (manufactured by Leica, product name: EMTIC 3X). The prepared cross section was observed with a scanning electron microscope (SEM) at a magnification range of 500 times to 5000 times, and the height of the protrusions and the number of protrusions (the number per length of the cross section of the removable adhesive tape) were measured. The measurement was performed at three random locations within a length range of 250 μm. The height of the protrusions was determined as the distance between the part where the interface between the undercoat layer and the adhesive layer was flat and the highest part of the filler. FIG. 3 is a schematic diagram illustrating a method for measuring the height of the protrusions. The distance from the highest part of the protrusion 40 to the undercoat layer 20 and the adhesive layer 30 (both arrows in the illustrated example) was determined. The number of fillers was converted to the number per mm, and the average of the three locations was determined as the number of fillers. In addition, for those in which the filler had fallen off during preparation of the cross section, the height and number of the filler particles were measured for the hollow portions formed by the fallen off filler.
2. Anchoring strength The substrates used in each Example and Comparative Example were subjected to a corona treatment. Next, the filler-containing undercoat layer forming composition used in each Example was applied to the corona-treated surface of the substrate to a thickness of 3 μm to form an undercoat layer. Thereafter, the adhesive layer forming composition used in each Example and Comparative Example was applied to the undercoat layer to a thickness of 20 μm to form an adhesive layer, and an evaluation sample was obtained. The evaluation sample was irradiated with ultraviolet light of 460 mJ/cm ² from a high-pressure mercury lamp to cure the adhesive layer, and then a cutter was used to make a cut in the adhesive layer in a direction perpendicular to the peeling direction. Thereafter, an adhesive tape (manufactured by Nitto Denko, product name: BT-315) was attached to the cured adhesive layer, and heated at 50° C. for 48 hours. Thereafter, the peeling strength (anchoring strength) was measured using a Tensilon tester (manufactured by A&D, product name: RTG-1210) when peeled at a tensile speed of 300 mm/min by T-peel. With regard to the peel strength (anchor strength) between the substrate and the undercoat layer, if the anchor strength is high, the adhesive layer and the adhesive tape will peel off first. In this case, the anchor strength was set to 8.0 N/50 mm or more.
If the anchoring force is 3.0 N/50 mm or more, the anchoring property is good.

The removable adhesive tape of the present invention can be suitably used in semiconductor processing applications.

REFERENCE SIGNS LIST 10: Substrate 20: Undercoat layer 30: Pressure-sensitive adhesive layer 40: Protruding portion 100: Removable pressure-sensitive adhesive tape

Claims (11)

A removable adhesive tape comprising, in this order, a substrate, an undercoat layer containing a binder resin and a filler, the filler being contained in an amount of 15 to 60 parts by weight per 100 parts by weight of the binder resin , and an adhesive layer containing an active energy ray-curable adhesive, the base polymer of which is an acrylic resin having a side chain double bond introduced therein;
At least a part of the filler has a protrusion protruding from the undercoat layer into the pressure-sensitive adhesive layer,
The interface between the undercoat layer and the pressure-sensitive adhesive layer has projections and recesses. The removable adhesive tape according to claim 1, wherein the filler is at least one selected from the group consisting of silica, aluminum oxide, and calcium carbonate. The removable adhesive tape according to claim 1 or 2, wherein the binder resin is a urethane resin. The removable adhesive tape according to any one of claims 1 to 3, wherein 50 mol % or more of the side chains of the acrylic resin with side chain double bonds are substituents having 8 or more carbon atoms. The removable adhesive tape according to any one of claims 1 to 4, wherein the adhesive layer further contains an isocyanate-based crosslinking agent. The removable adhesive tape according to any one of claims 1 to 5, wherein the height of the protrusions is 1 μm or more. The removable adhesive tape according to any one of claims 1 to 6, in which the number of protrusions is 10 or more per mm. The removable adhesive tape according to any one of claims 1 to 7, wherein the average particle size of the filler is 0.2 μm to 1.2 μm. The removable adhesive tape according to any one of claims 1 to 8, wherein the adhesive layer has an anchoring strength of 2N/50mm or more. The removable adhesive tape according to any one of claims 1 to 9, wherein the substrate contains at least one resin selected from the group consisting of polyethylene terephthalate resins, polyethylene naphthalate resins, and polyolefin resins. The removable adhesive tape according to claim 1 , which is used for semiconductor processing applications.