JP2000230159A - Substrate for adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substrate which is used for adhesive tapes exhibiting high adhesive strengths and has high adhesivity. SOLUTION: This substrate for adhesive tapes is obtained by forming an acrylic polymer layer having a thickness of 0.1-5 μm and having carboxyl groups in an amount of >=5 mgKOH/g. The substrate for adhesive tapes is also obtained by molding a photocation-polymerizable composition comprising 100 pts.wt. of a cation-polymerizable compound and 0.01-30 pts.wt. of a photocation- polymerization initiator into a sheet-like shape, and then irradiating the sheet- like product with light. Therein, 25-65 wt.% of the cation-polymerizable compound comprises an acrylic polymer consisting mainly of an alkyl acrylate and having a weight-average mol.wt. of >=10,000, and the photocation- polymerizable composition has a total cation-polymerizable functional group equivalent of <=5,000 g-resin/mol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate for an adhesive tape.

[0002]

2. Description of the Related Art Paper, cloth, nonwoven fabric, plastic film and the like have been used as a base material for an adhesive tape. However, depending on the use of the adhesive tape, for example, a polyethylene terephthalate (PET) film having excellent transparency and strength may be used. Polyethylene films with excellent chemical inertness may be used as base materials for pressure-sensitive adhesive tapes, respectively, and the surface of these base materials for pressure-sensitive adhesive tapes may be subjected to surface treatment such as corona discharge treatment, flame treatment, and ultraviolet treatment. Means have been taken to modify the surface of the base material by applying it to increase wettability and enhance anchor performance of the pressure-sensitive adhesive.

In particular, heat-resistant adhesive tapes used for fixing masking tapes and other electronic parts in the production of printed circuit boards have a heat-resistant adhesive property that does not peel off in a solder bath at a temperature exceeding 200 ° C. or in a firing step. Is required. As the pressure-sensitive adhesive component of such a heat-resistant pressure-sensitive adhesive tape, for example, a silicone-based pressure-sensitive adhesive or a thermosetting or light-curing pressure-sensitive adhesive having excellent heat resistance is used. For example, a polyimide film, a polyethylene naphthalate (PEN) film, a polyphenylene sulfide (PPS) film, a liquid crystal polymer (LCP) film, or the like having excellent heat resistance is used.

[0004] However, these heat-resistant base materials for adhesive tapes generally do not have sufficient anchoring performance with respect to the adhesive, and even when subjected to the above-mentioned surface treatment such as corona discharge treatment, flame treatment, and ultraviolet treatment, In particular, a double-sided pressure-sensitive adhesive tape may not be able to impart sufficient adhesive strength.

Japanese Patent Application Laid-Open No. Hei 9-279103 discloses that, prior to light irradiation, the adhesive has a tackiness, the curing proceeds slowly after the light irradiation, and the tackiness is not immediately lost. A new adhesive that can be adhered to the adherend by a simple means such as a laminator, and gradually cures even after the end of light irradiation, finally revealing a strong adhesive structure like an adhesive An ultraviolet post-curing adhesive sheet or the like has been proposed. The ultraviolet post-curing adhesive sheet,
Adhesive strength is dramatically improved compared to conventional adhesive tapes using adhesives. There is a risk of being destroyed.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above facts, and has been developed for pressure-sensitive adhesive tapes requiring high heat resistance and pressure-sensitive adhesive tapes exhibiting high adhesive strength. It is an object of the present invention to provide a pressure-sensitive adhesive tape base material having a high adhesiveness suitable for use as a base material. In addition, the "adhesive tape" in the present invention includes a "adhesive tape" whose adhesive strength is increased like an adhesive by a post-curing reaction.

[0007]

According to a first aspect of the present invention, there is provided a pressure-sensitive adhesive tape base material having a thickness of 0.1 to 5 μm and having a carboxyl group of at least 5 mgKOH / g on at least one surface of a film-like support. It is characterized in that a polymer layer is formed.

[0008] The base material for an adhesive tape according to the second aspect of the present invention provides a sheet of a cationic photopolymerizable composition containing 100 parts by weight of a cationically polymerizable compound and 0.01 to 30 parts by weight of a cationic photopolymerization initiator. A pressure-sensitive adhesive tape substrate formed and irradiated with light, comprising 25 to 6 cationically polymerizable compounds.
5% by weight is composed of an acrylic polymer whose main component is an alkyl acrylate and has a weight-average molecular weight of 10,000 or more, and the cationically polymerizable functional group equivalent of the entire photocationically polymerizable composition is 5000 g-resin / mol or less. It is characterized by the following.

The pressure-sensitive adhesive tape substrate according to the first aspect of the present invention has a thickness of 0.1 to 5 μm having a carboxyl group of 5 mgKOH / g or more on at least one surface of a film-like support.
The layer is not particularly limited as long as a layer of an acrylic polymer (hereinafter, abbreviated as a primer layer) is formed. Examples thereof include a polyester resin, a polyolefin resin, a polystyrene resin, and a polyvinyl acetate resin. Resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, chlorinated polyvinylidene chloride resin, polyamide resin, polyamideimide resin, polyimide resin, polyetherimide Resin, polyacetal resin, polyether sulfone resin, polysulfone resin, polyethylene naphthalate resin, polyarylate resin, polyphenylene sulfide resin, cellulose resin,
Synthetic resin films such as cellulose acetate resin,
Paper, cellophane, woven fabric, non-woven fabric, metal foil, metallized film, glass cloth, carbon cloth, etc. or a single piece of cloth, composite film of these films,
Alternatively, a primer layer may be formed on at least one surface of a film other than these or a reinforced film reinforced with a fibrous reinforcing material.

[0010] Among them, polyamide resin, polyamideimide resin, polyacetal resin, polyimide resin,
So-called engineering plastic resin films such as polyetherimide resin, polyethersulfone resin, polysulfone resin, polyethylene naphthalate resin, polyarylate resin, polyphenylene sulfide resin, etc. It is suitably used for applications.

These films or cloths are subjected to a surface treatment such as a corona discharge treatment, a flame treatment, and an ultraviolet irradiation treatment in order to further enhance the adhesion to the primer layer, and the surface thereof is made highly polar to enhance the activity. Is also good. Means for forming the primer layer on the film or cloth surface is not particularly limited, and examples thereof include a solvent casting method, an extrusion (lamination) method, a dipping method, and a roll coating method.

The primer layer comprises a layer of an acrylic polymer having a thickness of 0.1 to 5 μm and having a carboxyl group in the molecule of 5 mgKOH / g or more. The carboxyl group is introduced into the acrylic polymer molecule. Means for carrying out the method are not particularly limited. For example, acrylic acid, methacrylic acid, (anhydride) maleic acid, crotonic acid, fumaric acid, 2-acryloyloxyethyl (propyl) phthalic acid, β-acryloxypropionic acid (Acrylic acid dimer), β-acryloxypropionic acid-acrylic acid adduct (acrylic acid trimer), acrylic acid tetramer,
A monomer having a carboxyl group in a molecule such as 2-acryloyloxyethyl (propyl) succinic acid is copolymerized with another acrylic monomer, or an acrylic polymer is synthesized using a silane-based or thiol-based coupling agent. Examples of the method include modification with a carboxyl group-containing compound.

The acrylic monomer other than the monomer having a carboxyl group constituting the acrylic polymer is not particularly limited, and examples thereof include alkyl acrylate, alkyl methacrylate, acrylamide, acrylonitrile and the like. Can be These acrylic polymers may be copolymerized with a non-acrylic monomer or a functional group-containing vinyl monomer required for crosslinking, if necessary. Although these monomers are not particularly limited, for example, styrene, butadiene, isoprene, cumarone, vinyl acetate,
N-vinylpyrrolidone, N-vinyloxazoline, 2-
Hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, ε-caprolactam (meth) acrylate, diethylaminoethyl acrylate, and the like; macromonomers; and the like.

The means for copolymerization is not particularly limited, and a polymerization method such as radical polymerization or ionic polymerization can be adopted. In the former case, for example, the polymerization is performed by radical polymerization such as solution polymerization or bulk polymerization. There is no limitation on the use of a radical polymerization initiator, a chain transfer agent, a polymerization inhibitor, a radical activator (auxiliary agent) and the like which are activated by light, heat or the like used in the copolymerization reaction.

The weight average molecular weight of the obtained acrylic polymer is not particularly limited, but is preferably 1
It is about 10,000 to 3,000,000. If the weight average molecular weight of the acrylic polymer is too small, the cohesive strength may be insufficient and the adhesive strength may be reduced. If the weight average molecular weight is too large, the viscosity may be increased and the applicability may be reduced.

The glass transition temperature (Tg) of the obtained acrylic polymer layer is preferably 50 ° C. or less. Tg
If it is too high, the elastic modulus at room temperature increases, for example, when an impact force such as peeling off the tape is applied, cracks are likely to occur, and when these breaking strengths are high, cracks enter the primer layer, The tape substrate may be broken.

As one of means for lowering the Tg of the acrylic polymer to 50 ° C. or lower, a compounding ratio of an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms as an acrylic monomer to be copolymerized is used. There are ways to enhance it. In particular, when the compounding ratio of the alkyl acrylate having 1 to 4 carbon atoms in the alkyl group is increased, the high polarity increases the adhesive strength between the adhesive tape substrate and the adhesive, and the impact force when the tape is peeled off. Cracks generated in the primer layer can be prevented to increase fracture toughness.

Examples of the alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate,
Examples thereof include n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, and isononyl acrylate.

The acrylic polymer forming the primer layer further increases the cohesive force by crosslinking, and can particularly increase the breaking strength in the shear direction.
The degree of crosslinking of the acrylic polymer is not particularly limited, but is preferably 60% or more as an insoluble component (gel component) in ethyl acetate because a high adhesive force can be obtained.

The means for crosslinking the acrylic polymer is not particularly limited, and examples thereof include a method using a crosslinking agent, a method using heat, an electron beam, an electromagnetic wave (light), and the like. Examples of the crosslinking agent that react with a functional group include, for example, isocyanate-based, chelate-based, epoxy-based, silane-based, and thiol-based crosslinking agents.
Examples of a type in which a crosslinkable monomer is copolymerized during polymerization of an acrylic polymer include polyfunctional acrylates such as hexanediol diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate.

The thickness of the primer layer made of the acrylic polymer is 0.1 to 5 μm. When the thickness of the primer layer is less than 0.1 μm, sufficient adhesion between the adhesive tape substrate and the adhesive cannot be obtained. When the thickness exceeds 5 μm, the cohesive force is insufficient, and the adhesive force of the adhesive is insufficient. If the primer layer is too high, the primer layer may be agglomerated and destroyed, and the adhesive strength is not increased in proportion to the thickness but saturates.

The cationically polymerizable compound used in the pressure-sensitive adhesive tape substrate according to the second aspect of the present invention is a compound having a cationically polymerizable functional group in the molecule. These cationically polymerizable functional groups are not particularly limited, but include, for example, epoxy, alicyclic epoxy, hydroxyl, episulfide, ethyleneimine, and vinyl ether groups. The system compound is preferably used because it has high reactivity and high heat resistance.

As the epoxy compound, for example,
Bisphenol A type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin and the like, and trade names such as "Epicoat" manufactured by Yuka Shell Epoxy, "Adeka Resin" and "Adeka Optomer" manufactured by Asahi Denka Co., Ltd. It is commercially available at

In the present invention, the cationically polymerizable compound is
25 to 65% by weight of which has an alkyl acrylate as a main component and a weight average molecular weight of 10,000 or more, preferably 100,000 to
It is composed of 3,000,000, more preferably 300,000 to 2,000,000 acrylic polymers. If the molecular weight of the acrylic polymer is too large, the viscosity will increase, and the film-forming property will decrease. If the molecular weight is too low, the cohesive force will decrease, and the strength of the resulting adhesive tape base will be reduced.

As the acrylic polymer, those having the above-mentioned cationically polymerizable functional group in the molecule are used. The acrylic polymer has an alkyl acrylate as a main component, and a compound having a cationically polymerizable functional group, for example, glycidyl (meth) acrylate, hydroxyalkyl acrylate, ε-caprolactam acrylate, epoxy acrylate, or the like is copolymerized to form an intramolecular compound. Can be introduced with a cationically polymerizable functional group.

These acrylic polymers may be copolymerized with a monomer other than an acrylic polymer or a functional group-containing vinyl monomer required for crosslinking, if necessary. Although these monomers are not particularly limited, for example, styrene, butadiene, isoprene, coumarone, indene, vinyl acetate, N-vinylpyrrolidone, N-vinyloxazoline, 2-hydroxyethyl (meth) acrylate, Hydroxybutyl (meth) acrylate,
ε-caprolactam (meth) acrylate, diethylaminoethyl acrylate, etc .; macromonomers;

When the weight fraction of the acrylic polymer in the cationically polymerizable compound is less than 25% by weight, the adhesion to the pressure-sensitive adhesive is reduced, and the adhesive strength of the pressure-sensitive adhesive tape produced using the same is lowered. When the content exceeds 65% by weight, the heat resistance decreases, so that the content is limited to the above range of 25 to 65% by weight.

Further, the cationically polymerizable functional group equivalent of the entire photocationically polymerizable composition is 5000 g-resin /
If the amount exceeds mol, the crosslinking density is reduced and the heat resistance is reduced, so that it is limited to the above range.

The cationic photopolymerization initiator may be either an ionic photoacid generating type or a nonionic photoacid generating type, and is used in an amount of 0.01 to 30 parts by weight based on 100 parts by weight of the cationic polymerizable compound. Is done. If the amount is less than 0.01 part by weight, the curing rate is small, and the unreacted material may lower the strength of the base material. Conversely, if the amount exceeds 30 parts by weight, the reaction starts with low energy, so that it is weak like room light. The curing reaction may proceed even with light, shortening the pot life,
The curing speed itself reaches saturation, which is economically disadvantageous.

Examples of the ionic photoacid generating type photocationic polymerization initiator include onium salts such as aromatic diazonium salts, aromatic halonium salts, and aromatic sulfonium salts;
Organometallic complexes such as iron-allene complex, titanocene complex, and arylsilanol-aluminum complex are exemplified. Examples of commercially available photocationic polymerization initiators of the ionic photoacid generation type include, for example, Asahi Denka Co., Ltd.
Product name "Optomer SP-150", "SP-17
0 ”, manufactured by General Electric Company, trade name“ UVE-
1014 ", manufactured by Sartomer, Inc., trade name" CD-101 "
2 "and the like.

Examples of the nonionic photoacid generating type cationic photopolymerization initiator include, for example, nitrobenzyl ester,
Phosphoric acid esters, sulfonic acid derivatives, phenolsulfonic acid derivatives, N-hydroxyimidosulfonates, diazonaphthoquinones and the like can be mentioned. These photocationic polymerization initiators may be used alone or in combination of two or more. The curing reaction may be performed in two or more steps by using a plurality of kinds of cationic photopolymerization initiators having different effective active wavelengths. Furthermore, these photopolymerization initiators may be used in combination with other photopolymerization initiators such as, for example, a photoradical polymerization initiator and a photoanionic polymerization initiator. In this case, the wavelength of the light for activating the photo-radical polymerization initiator or the photo-anionic polymerization initiator does not necessarily need to be the same as the wavelength of the light for activating the photo-cationic polymerization initiator.

The light that activates the cationic photopolymerization initiator is:
Infrared, visible, ultraviolet, X-ray, α-ray, β-ray, γ-ray,
An electron beam or the like is used, but ultraviolet rays and light having a longer wavelength are preferably used from the viewpoint of cost, safety, etc.
Ultraviolet rays with a wavelength of 00 to 400 nm have a high energy amount and are easy to handle, so that they can be used very effectively.
Examples of the ultraviolet light source include a mercury lamp, a metal halide lamp, and a chemical lamp.

The base material for an adhesive tape of the present invention may be optionally provided, for example, without departing from the spirit of the present invention.
Polyester resin, polyamide resin, polyolefin resin, silicone resin, urethane resin, urea resin, cellulose resin, cellulose acetate resin, vinyl chloride resin, vinylidene chloride resin, vinyl butyral resin,
Various rubbers, inorganic fillers, organic fibers such as rayon, inorganic fibers, woven fabrics, nonwoven fabrics, paper, metal foils and the like can be mixed or laminated. By combining with these materials, the elastic modulus and hardness of the adhesive tape substrate of the present invention can be adjusted. In particular, by compounding a flexible material such as urethane resin or rubber, impact resistance, flexibility, deformation followability can be further enhanced, and inorganic fillers and fibers,
By combining woven fabric, nonwoven fabric, etc., the elastic modulus and mechanical strength can be further enhanced.

The substrate for an adhesive tape of the present invention is prepared by forming a film from these compositions and combining the above-mentioned various materials. Means for forming the above composition into a film is not particularly limited, and examples thereof include an extrusion method, a casting method, a rolling method, and a laminating method. In the film-forming step, various auxiliary materials such as a solvent, a lubricant, a film-forming stabilizer, an antifoaming agent, a filler, a plasticizer, an antioxidant, an anti-blocking agent, and a separator may be used.

The thickness of the pressure-sensitive adhesive tape substrate of the present invention is determined by the use of the pressure-sensitive adhesive tape, and is not particularly limited.
Those having a thickness of about 0 μm are widely used.

The photocationic polymerizable composition formed into a film may be irradiated with light having an active wavelength of the photocationic polymerization initiator to react at least 70% of the cationic polymerizable functional groups in the composition. Preferably, light irradiation may be performed until the surface becomes tack-free. The cationic photopolymerization reaction can be adjusted by heat or humidity. If the reaction rate is lower than 70%, not only the strength of the obtained film is lowered but also the heat resistance may be lowered. The reaction rate is calculated by quantifying the cationically polymerizable functional group in the composition by a titration method or an IR method.

The pressure-sensitive adhesive tape substrate of the present invention may be coated on both sides with a pressure-sensitive adhesive to form a double-sided pressure-sensitive adhesive tape. Is also good. As these pressure-sensitive adhesives, for example, various pressure-sensitive adhesives and pressure-sensitive adhesives such as silicone-based, acrylic-based, rubber-based, urethane-based, polyester-based, and olefin-based pressure-sensitive adhesives are used depending on the application. In particular, in the case of the adhesive tape substrate according to claim 2, a carboxyl group, a sulfonium group,
When a pressure-sensitive adhesive containing a hydroxyl group, an amino group, an ethyleneimine group, a phosphoric acid group, or the like is used, it reacts with the cationically polymerizable functional group of the base material to obtain high adhesion strength.

The means for applying the pressure-sensitive adhesive is not particularly limited, and the pressure-sensitive adhesive may be directly coated on one or both sides of the substrate for a pressure-sensitive adhesive tape by a method such as a casting method or an extrusion method. It may be applied by a transfer method. Further, after applying the pressure-sensitive adhesive by a method such as a casting method or an extrusion method simultaneously or continuously with the formation of the film for the pressure-sensitive adhesive tape substrate of the present invention, photocationic polymerization may be advanced by light irradiation.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described. (Example 1) 70 parts by weight of methyl methacrylate, 30 parts by weight of acrylic acid, and a radical photopolymerization initiator (BASF) were applied to one side of a 50 μm-thick PET film that had been subjected to corona discharge treatment so that the surface wetting tension became 51 dyn / cm. Co., Ltd., trade name "Lucillin TPO") 1 part by weight of a photo-radical polymerizable resin composition is applied by a gravure roll, and the coated surface is irradiated with ultraviolet light having a central wavelength of 365 nm by a mercury lamp in a nitrogen inert atmosphere. A substrate for a pressure-sensitive adhesive tape having a 2 μm-thick carboxyl-containing acrylic polymer layer was formed. The weight average molecular weight of the obtained acrylic polymer determined by GPC analysis was 590,000.

Example 2 75 parts by weight of ethyl acrylate, 25 parts by weight of acrylic acid and 0.0 part of dodecanethiol
5 parts by weight were dissolved in 150 parts by weight of ethyl acetate, nitrogen was sufficiently blown into the separable flask to purge dissolved oxygen, and the mixture was heated with stirring at 76 ° C. under a nitrogen atmosphere to obtain azobisisobutyronitrile (AIBN). ) 0.1 part by weight was added and subjected to thermal radical polymerization to prepare a solution of an acrylic polymer having a carboxyl group in ethyl acetate. The weight average molecular weight of the obtained acrylic polymer was 440,000.

On one side of a PET film of the same type as used in Example 1, an ethyl acetate solution of an acrylic polymer obtained by a two-roll coater was applied, and dried in a drying oven.
It dried at 0 degreeC for 4 minutes, and produced the base material for adhesive tapes in which the 1-micrometer-thick acrylic polymer layer containing a carboxyl group was formed.

Example 3 In place of the heat-radical polymerizable composition of Example 2, 87 parts by weight of butyl acrylate and β-
10 parts by weight of carboxyethyl acrylate, 3 parts by weight of 2-hydroxyethyl acrylate, 0.2 parts by weight of dodecanethiol, 100 parts of ethyl acetate and 0.1 parts of AIBN.
A carboxyl group-containing acrylic polymer ethyl acetate solution was prepared in the same manner as in Example 2 except that 1 part by weight was used. The weight average molecular weight of the obtained acrylic polymer was 270,000. Next, an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., based on 100 parts by weight of the obtained carboxyl-containing acrylic polymer.
An ethyl acetate solution of an acrylic polymer to which 0.2 part by weight of trade name "Coronate L" was added was applied on one side of a PET film of the same type as used in Example 1 by a two-roll coater, and then dried in a drying furnace. And dried at 120 ° C. for 4 minutes, and then aged at 50 ° C. for 72 hours to be cured, thereby producing a base material for a pressure-sensitive adhesive tape having a carboxyl group-containing acrylic polymer layer having a thickness of 0.8 μm. .

Comparative Example 1 A substrate for an adhesive tape was produced in the same manner as in Example 1 except that the thickness of the acrylic polymer layer containing a carboxyl group was 0.05 μm.

Comparative Example 2 Except that the thickness of the acrylic polymer layer containing a carboxyl group was 10 μm,
In the same manner as in Example 2, a substrate for an adhesive tape was produced.

(Comparative Example 3) Instead of the acrylic polymer obtained in Example 2, an amino group-containing acrylic polymer (trade name "Polyment NK350", manufactured by Nippon Shokubai Co., Ltd., T
g = 40 ° C., amine hydrogen equivalent is 400 g-solid /
eq. ) Was used in the same manner as in Example 2 except that the substrate for pressure-sensitive adhesive tape was prepared.

Comparative Example 4 The same kind of PET film as used in Example 1 was used as it was as a substrate for an adhesive tape.

To evaluate the performance of the pressure-sensitive adhesive tape substrates obtained in Examples 1 to 3 and Comparative Examples 1 to 4, the gel fraction and Tg of the acrylic polymer layer containing a carboxyl group were evaluated.
Was measured by the following method. Table 1 shows the measurement results.

The gel fraction was measured by immersing the sample in a 200-fold amount of ethyl acetate of the resin component of the acrylic polymer layer, shaking it with a shaker at 120 reciprocations / minute, at an amplitude of 45 mm for 24 hours, and using a 200 mesh mesh. The weight of the solids separated by filtration was measured and indicated by weight fraction.

The Tg was measured by measuring the dynamic viscoelastic spectrum of the resin component of the sample acrylic polymer layer,
It was determined from the peak value of tan δ.

Further, in order to evaluate the performance of the adhesive tape base materials obtained in Examples 1 to 3 and Comparative Examples 1 to 4, adhesive tapes were prepared from the following adhesive compositions by a transfer method.

(Preparation of pressure-sensitive adhesive composition and pressure-sensitive adhesive tape) Poly (ethyl acrylate / glycidyl methacrylate) =
98 parts by weight / 2 parts by weight, weight average molecular weight by GPC 5
50,000, Tg = −18 ° C.) 50 parts by weight, bisphenol A
30 parts by weight of a type epoxy resin (trade name “Epicoat # 828” manufactured by Yuka Shell Epoxy) and a flexible epoxy resin (trade name “Epicoat # 29” manufactured by Yuka Shell Epoxy)
2 ") 50 μm thick PET obtained by releasing a pressure-sensitive adhesive composition comprising 20 parts by weight and 2 parts by weight of a cationic photopolymerization initiator (trade name“ OPTMER SP170 ”manufactured by Asahi Denka Co., Ltd.)
The film was applied to a thickness of 100 μm to form a pressure-sensitive adhesive layer.
The adhesive tape was prepared by transferring to a carboxyl group-containing acrylic polymer layer of a substrate for an adhesive tape or a surface-treated surface equivalent thereto at a temperature of 5 ° C., a linear pressure of 5 kg / cm, and a speed of 0.8 m / min.

(Preparation of test piece) The release PET of the pressure-sensitive adhesive tape prepared above was peeled off, and a UV ray having a center wavelength of 360 nm was applied to the pressure-sensitive adhesive layer using a mercury lamp at a wavelength of 3 J / cm ² (“UVIMAP” manufactured by ETI). Measurement), and one minute after the irradiation, the laminate was laminated so as to be in contact with the primer layer of the other tape base material. The laminate was further cured at 60 ° C. for 3 days.
A test piece for mold peel strength measurement was prepared. Further, a test piece for measuring a shear adhesive force having an adhesive area of 10 mm × 10 mm was prepared.

(T-Type Peeling Strength Test) With respect to the T-type peeling strength test specimen, the peeling speed was set to 300 mm / min.
m / min, the peel strength was measured at room temperature, and the peel (break) form was observed. (Shear Adhesion Test) The shear adhesion of the test piece for measuring shear adhesion was measured at a shear rate of 10 mm / min. The test results are shown in Table 1.

[0054]

[Table 1]

The pressure-sensitive adhesive tapes using the pressure-sensitive adhesive tape substrates of Examples 1 to 3 are all pressure-sensitive adhesive tape-based pressure-sensitive adhesive tape substrates of Comparative Example 4 which are made of a PET film that has just been subjected to a corona discharge treatment. It shows high adhesive strength as compared with. This is presumed to be due to an increase in the adhesion between the PET film of the substrate and the pressure-sensitive adhesive via the acrylic polymer layer containing a carboxyl group. In the pressure-sensitive adhesive tape using the pressure-sensitive adhesive tape base material of Comparative Example 1, the thickness of the carboxyl group-containing acrylic polymer layer was too small to exhibit a sufficient anchor effect. When the thickness of the acrylic polymer layer containing a carboxyl group becomes too thick, such as a pressure-sensitive adhesive tape using a base material, the adhesive strength increases to some extent, but causes cohesive failure in the acrylic polymer layer. No improvement in adhesion can be expected.

The pressure-sensitive adhesive tape using the pressure-sensitive adhesive tape substrate of Example 1 was cut by the material destruction of the substrate in the high-speed peeling test, whereas the pressure-sensitive adhesive tape substrate of Example 2 was used. The pressure-sensitive adhesive tape shows high peel strength until cohesive failure occurs in the pressure-sensitive adhesive layer. This is presumed to be due to the fact that the Tg of the carboxyl group-containing acrylic polymer layer was high, the destructive force was concentrated instantaneously when the layer was peeled, cracks were formed, and the substrate was torn by the impact. In contrast, the carboxyl group-containing acrylic polymer layer of Example 2 has a low Tg and is flexible, so that the above-mentioned breaking stress is not concentrated on the layer, but is presumed to be caused by being dispersed in the pressure-sensitive adhesive layer. Is done.

Further, in the pressure-sensitive adhesive tape using the pressure-sensitive adhesive tape base material of Example 3, the acrylic polymer layer containing a carboxyl group was crosslinked to exhibit a high gel fraction, and the shear adhesive strength was greatly improved. . On the other hand, Example 1 or 2
In the acrylic polymer, the primer layer was displaced due to non-crosslinking, and as a result, the shear adhesive strength as in Example 3 could not be obtained.

As described above, by lowering the Tg of the acrylic polymer layer containing a carboxyl group, it is possible to alleviate the instantaneous destruction and the impactful destructive force at the time of high-speed peeling. It can be seen that the strength can be increased and a strong adhesion state can be exhibited.

(Example 4) Bisphenol A type epoxy resin (trade name "Epicoat #", manufactured by Yuka Shell Epoxy Co., Ltd.)
828 "), 50 parts by weight of a copolymer (weight average molecular weight: 670,000) consisting of 50 parts by weight, 95% by weight of ethyl acrylate and 5% by weight of glycidyl methacrylate, and a cationic photopolymerization initiator (trade name" OPTMER SP17 "manufactured by Asahi Denka Co., Ltd.)
0 ") 1 part by weight and 150 parts by weight of ethyl acetate were uniformly stirred and dissolved, cast on a release-treated PET film having a thickness of 50 μm so that the thickness after drying would be 50 μm, and 100 ° C. After drying for 4 minutes in a hot oven, a cast film was obtained.
After irradiating with UV at 1 J / cm ^{2, the} substrate was cured in a hot oven at 150 ° C. for 1 minute to prepare a substrate for an adhesive tape. The reaction rate of the photopolymerization reaction was measured by a titration method,
6%.

Example 5 An alicyclic epoxy resin (trade name “OPTMER K” manufactured by Asahi Denka Co., Ltd.) was used in place of the bisphenol A type epoxy resin of the cationic photopolymerizable composition of Example 4.
RM2110 ”) and 60 parts by weight of a copolymer (weight average molecular weight: 670,000) composed of 95% by weight of ethyl acrylate and 5% by weight of glycidyl methacrylate.
A base material for an adhesive tape was produced in the same manner as in Example 4 except that the amount was 0 parts by weight. The conversion of the photopolymerization reaction was measured by a titration method, and was 99%.

(Example 6) Bisphenol A type epoxy resin and 95% by weight of ethyl acrylate, glycidyl methacrylate 5 in the cationic photopolymerizable composition of Example 4
Acrylic rubber-dispersed bisphenol A type epoxy resin (trade name “Eposet 328”, manufactured by Nippon Shokubai Co., Ltd.) 45 is used instead of the copolymer (wt.
Except that 55 parts by weight of a copolymer (weight average molecular weight: 500,000) consisting of 95 parts by weight, methyl acrylate 95% by weight, and glycidyl methacrylate 5% by weight was used, a substrate for an adhesive tape was produced in the same manner as in Example 4. . The reaction rate of the photopolymerization reaction was 79% as measured by a titration method.

(Comparative Example 5) A PET film having a thickness of 50 μm (trade name “S-5” manufactured by Teijin Limited) as a base material for an adhesive tape.
0 ").

Comparative Example 6 A polyimide film having a thickness of 50 μm (trade name “Kapton 200H” manufactured by DuPont) was used as a base material for an adhesive tape.

In order to evaluate the heat resistance of the pressure-sensitive adhesive tape substrates obtained in Examples 4 to 6 and Comparative Examples 5 and 6, each substrate was left in an oven at 250 ° C. without load for 10 minutes. The heat shrinkage was measured. All measurements were performed in the MD direction. Table 2 shows the measurement results.

Further, in order to evaluate the performance of the base materials for pressure-sensitive adhesive tapes obtained in Examples 4 to 6 and Comparative Examples 5 and 6, pressure-sensitive adhesive compositions having the following compositions and pressure-sensitive adhesive tapes were prepared by a transfer method. .

(Preparation of pressure-sensitive adhesive composition and pressure-sensitive adhesive tape) 100% by weight of a copolymer (weight-average molecular weight: 700,000) composed of 96% by weight of butyl acrylate, 3% by weight of acrylic acid and 1% by weight of 2-hydroxyethyl methacrylate Parts were uniformly dissolved in 100 parts by weight of ethyl acetate, and 0.1 part by weight of an epoxy-based curing agent "E-5C" (manufactured by Soken Chemical Co., Ltd.) was blended as a crosslinking agent, and a 50 μm-thick release-treated P was mixed.
Apply it on a ET film with a roll coater so that the thickness after drying becomes 50 μm,
Dried for minutes. The obtained pressure-sensitive adhesive layer was laminated on both surfaces of the pressure-sensitive adhesive tape substrates obtained in Examples 4 to 6 and Comparative Examples 5 and 6 at room temperature to prepare a double-sided pressure-sensitive adhesive tape.

Each of the obtained double-sided adhesive tapes was subjected to JIS
A SUS304 steel plate polished according to Z0237 was laminated at room temperature under the conditions of a linear pressure of 2 kg / cm and a speed of 1 m / min, and a SUS304 steel foil having a thickness of 50 μm was similarly bonded. After bonding, leave in an oven at 100 ° C for 1 hour,
The 180 ° peel adhesion was measured in an atmosphere at 100 ° C. The measurement results are shown in Table 2. The functional group equivalents of the pressure-sensitive adhesive tape substrates of Examples 4 to 6 are also shown in Table 2.

[0068]

[Table 2]

As is clear from Table 2, the double-sided pressure-sensitive adhesive tapes using the pressure-sensitive adhesive tape substrates of Examples 4 to 6 exhibited high adhesive strength in the 180-degree peeling adhesive strength test, and all exhibited cohesion in the pressure-sensitive adhesive layer. It was broken, and it was confirmed that the adhesive tape base material and the adhesive layer had high adhesion. On the other hand, the double-sided pressure-sensitive adhesive tapes using the base materials of Comparative Examples 5 and 6 both show base-material interfacial destruction, low 180-degree peel adhesion, and insufficient adhesion between the base material and the pressure-sensitive adhesive layer. Is shown.

Further, the base materials for pressure-sensitive adhesive tapes of Examples 4 to 6 all have a low heat shrinkage and show excellent heat resistance, whereas the base material of Comparative Example 5 has a particularly large heat shrinkage. It could not be used for applications requiring heat resistance.

[0071]

Since the substrate for pressure-sensitive adhesive tape of the present invention is constituted as described above, high adhesiveness with the pressure-sensitive adhesive can be obtained without performing any special surface treatment on the substrate. In the case of the pressure-sensitive adhesive tape substrate according to the second aspect, since a certain amount or more is cured by the polymerization of the cationically polymerizable compound, the substrate exhibits high heat resistance.

Continued on the front page F-term (reference) 4F006 AA02 AA12 AA15 AA16 AA17 AA18 AA20 AA32 AA35 AA38 AA39 AA40 AA51 AB24 AB62 AB64 AB65 AB66 BA01 CA00 EA00 EA01 EA03 4F100 AK25A AK25B AK25 BA03 BA02 BA03 BA07 BA02BA07 BA02BA03A YY00B 4J004 AA05 AA07 AA10 AA11 AA14 AB01 CA02 CA03 CA04 CA05 CA06 CA08 CB01 CB02 CC03 CD05 FA05 FA08

Claims (2)

[Claims] 1. A film-like support having at least one surface provided with
Thickness having a carboxyl group of 5 mgKOH / g or more.
A substrate for an adhesive tape, comprising a layer of an acrylic polymer having a thickness of 1 to 5 μm. 2. A pressure-sensitive adhesive tape base obtained by molding a photo-cationic polymerizable composition containing 100 parts by weight of a cationically polymerizable compound and 0.01 to 30 parts by weight of a photo-cationic polymerization initiator into a sheet and irradiating the sheet with light. 25-65% by weight of the cationically polymerizable compound is composed of an acrylic polymer having an alkyl acrylate as a main component and having a weight average molecular weight of 10,000 or more, and the cationically polymerizable composition as a whole is cationically polymerizable. A substrate for an adhesive tape, wherein the functional group equivalent is 5000 g-resin / mol or less.