JPH06346033A - Production or pressure-sensitive adhesive tape - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive tape excellent in prevention of disturbance between two acrylic adhesive layers, adjusting property of adhesive characteristics, resistance to shearing stress, workability and economical efficiency by carrying out crosslinking reaction of a specific group with a specific group in the interface between these adhesive layers and a photosetting layer through the photosetting layer between these acrylic adhesive layers. CONSTITUTION:Two adhesive layers consisting essentially of (meth)acrylic acid alkyl ester-based polymers are laminated through a photosetting layer being liquid at ambient temperature, and then, this photosetting layer is subjected to photosetting and crosslinking reaction between an active hydrogen- containing functional group such as hydroxyl group or carboxyl group and a reactive functional group such as isocyanate group, epoxy group or aziridine group at the interface between this photosetting layer and the two adhesive layer to provided the objective adhesive tape having a multilayer structure consisting of the adhesive layer, the photosetting layer and the adhesive layer multilayered in this order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pressure-sensitive adhesive tape having a multi-layered adhesive layer having excellent shear stress resistance.

[0002]

2. Description of the Related Art Conventionally, a pressure-sensitive adhesive tape such as a double-sided adhesive tape has a high wettability to an adherend,
It has been required to have both the adhesive properties and the contradictory properties of high cohesive strength. Further, when the adherends have different surface characteristics, it is difficult for the pressure-sensitive adhesive having the same composition to exert good adhesive properties on both adherends. Often processed in a way that balances the intermediate characteristics of.

In order to improve these, two or more kinds of pressure-sensitive adhesives having different compositions are used to form a multilayer structure.
It improves the adhesiveness and anchoring property to different adherends and supports, and changes the composition and physical properties of the surface layer that requires a strong bond with the adherend and the internal layer that requires high cohesion There is an attempt to do the control of.

For example, Japanese Patent Application Laid-Open No. 54-139946 discloses a pressure-sensitive adhesive tape having a multi-layered adhesive layer composed of two or more compositions having different shear creep compliances. However, it is said that this tape is particularly useful for applications such as diaper tapes and cloth display labels where the adherend has an irregular surface and is subjected to various external stresses during use.

However, a pressure-sensitive adhesive tape having an adhesive layer having a multi-layered structure as described above has a weak bonding force between the layers,
There is a drawback that the layers are easily peeled off due to external stress such as shearing force. This is because the above-mentioned multilayer structure is simply a film-like adhesive layer made by a solution cast method or the like, so that sufficient mixing, permeation, and bonding of molecules between each layer are difficult to occur, It is presumed that the layers are connected only by intermolecular force, ionic bond force, and relatively weak force.

[0006] Therefore, Jim Mahman et al.
No. 790, consisting of a plurality of superposed layers, at least one outer layer being a pressure sensitive adhesive layer, adjacent layers defining an interface between the adjacent layers, each of which is photopolymerized. Polymer chains, which extend from one matrix of the layers through this interface into the matrix of the adjacent layer, and the polymer chains are separated from the matrix of each adjacent layer before polymerization. We propose a pressure-sensitive adhesive tape consisting of polymerized monomers that have migrated, thus preventing the layers from delaminating.

Further, Murakami et al., JP-A-1-263182.
In the publication, the number of carbon atoms of the alkyl group on the carrier is 2 to
14 (meth) acrylic acid alkyl esters 50 to 1
00% by weight and vinyl monomer 50 copolymerizable therewith
Of at least two types of partial polymer films having a residual ratio of 1 to 60% by weight, obtained by partially polymerizing an acrylic monomer of 1 to 0% by weight. It is shown that the bonding strength between the layers can be increased by polymerizing the residual monomers in each film after laminating and pressure bonding so that the compositions are different.

[0008]

However, in the method of Jimma-Mann et al., It is necessary to successively coat a coatable composition containing a monomer in multiple layers, and at that time, mechanical coating between layers is required. There is a problem that various mixing occurs. For this reason, Jimma-Mann et al. In JP-A-1-121386 propose a method of coating in parallel in multiple layers by coextrusion. However, in order to prevent mixing between layers, the composition There is a problem that the viscosity is required to be restricted and the coating device becomes expensive. Further, in the method of Murakami et al., The mechanical strength of the partial polymer film is weak, so that there is a problem that workability in the laminating step is deteriorated.

In order to solve such a problem, a method of laminating two layers polymerized in advance can be considered, but it is difficult to obtain a sufficient bond strength between the layers by simply sticking them together. Generally, it is known to use an undercoating agent to improve the bond strength between layers (for example, Japanese Patent Publications No. 50-20108 and 39-30054), but there are problems such as an increase in treatment steps. It is not a preferable method because it occurs newly.

In view of the above-mentioned conventional circumstances, the present invention provides a pressure-sensitive adhesive tape having a multi-layered adhesive layer having a high bond strength between layers, which has good workability and economical efficiency without causing inter-layer mixing. The object is to provide a method that can be manufactured.

[0011]

[Means for Solving the Problems] To solve the above-mentioned problems, the present inventors have laminated two adhesive layers via a photocurable composition layer which is liquid at room temperature, and then the composition described above. When the layer is photo-cured and a specific cross-linking reaction is carried out at the interface between the photo-cured layer and each adhesive layer, the adhesive layer having a multi-layer structure with a large bond strength between layers causes disturbance between the layers. The present invention has been accomplished by knowing that the workability and the economical efficiency can be obtained without causing the occurrence.

That is, according to the present invention, two adhesive layers containing a (meth) acrylic acid alkyl ester polymer as a main component are laminated via a photocurable composition layer which is liquid at room temperature, and The composition layer is photocured, and at the interface between the photocurable layer and the two adhesive layers, a crosslinking reaction is caused by the active hydrogen-containing functional group and the reactive functional group,
The present invention relates to a method for producing a pressure-sensitive adhesive tape, which is characterized in that a pressure-sensitive adhesive tape having a multilayer structure including an adhesive layer, a photocurable layer and an adhesive layer is obtained.

[0013]

In the present invention, first, two adhesive layers containing an alkyl (meth) acrylic acid ester polymer (hereinafter referred to as an acrylic polymer) as a main component are formed. Both adhesive layers may be the same or different, but the photocurable layer contains a reactive functional group in order to cause a crosslinking reaction at the interface with the photocurable layer. In this case, a functional group containing active hydrogen needs to be contained, and when the same layer contains a functional group containing active hydrogen, a reactive functional group needs to be contained.

In order to include these functional groups in the adhesive layer, for example, when synthesizing an acrylic polymer, the main component is (meth) acrylic acid alkyl ester, and
A monomer containing a reactive functional group may be used, or a monomer containing a functional group containing active hydrogen may be used. Also, even if a polyfunctional crosslinking agent is further reacted with an acrylic polymer synthesized using a monomer containing a functional group containing active hydrogen, a reactive functional group may be introduced into the acrylic polymer. Good.

Examples of alkyl (meth) acrylates include methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Those in which the alkyl group such as isooctyl (meth) acrylate and isononyl (meth) acrylate have a carbon number in the range of 1 to 14 are preferably used. As the reforming monomer, various vinyl-based monomers such as vinyl acetate and styrene are used, and 50% by weight or less of the total amount of the monomers, preferably 30
You may use it in the ratio of less than weight%.

As the monomer containing a reactive functional group, a monoethylenically unsaturated monomer in which the above functional group is an isocyanate group, an epoxy group or an aziridine group is used, and an example thereof is isocyanate ethyl. Isocyanate group-containing monomers such as methacrylate, glycidyl acrylate, glycidyl group-containing monomers such as glycidyl methacrylate, and aziridine group-containing such as 2- (1-aziridinyl) ethyl methacrylate I can mention the monomer.

The amount of the monomer containing the reactive functional group used is
Usually, the amount is 0.001 to 10% by weight, preferably 0.01 to 2% by weight, based on the whole monomer. If the amount is too small, the crosslinking reaction at the interface with the photocurable layer is insufficient, and sufficient interlayer adhesion cannot be obtained. If the amount is too large, crosslinking proceeds too much to obtain sufficient adhesive properties.

The monomer containing an active hydrogen-containing functional group is preferably a monoethylenically unsaturated monomer whose functional group is a hydroxyl group or a carboxyl group.
There are carboxyl group-containing monomers such as (meth) acrylic acid and itaconic acid, and hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. Further, 2-acrylamidopropanesulfonic acid whose functional group is a sulfonic acid group, and whose functional group is a methylol group, an amino group or a silanol group.
For example, a monoethylenically unsaturated monomer such as a vinyl group may be used.

A monomer containing a functional group containing active hydrogen is
The functional group is directly involved in the cross-linking reaction with the photo-curable layer, or when it is reacted with the polyfunctional cross-linking agent to be converted into the reactive functional group and then involved in the cross-linking reaction. At the same time, it may itself function as a component that contributes to the improvement of adhesive properties. The amount of the monomer containing the active hydrogen-containing functional group is usually 1 to 30% by weight, preferably 2% by weight of the whole monomer in consideration of the above-mentioned function.
It is preferable to be in the range of 20% by weight. Outside this range, sufficient interlayer adhesiveness may not be obtained, or the adhesive properties may be impaired, which is not preferable.

The polyfunctional cross-linking agent introduces a reactive functional group into the acrylic polymer by reacting with a functional group containing active hydrogen, so that two or more isocyanate groups and an epoxy group are introduced into the molecule. Those having a group or an aziridine group are used. This polyfunctional crosslinking agent functions not only for introducing the above-mentioned reactive functional group, but also as a component that contributes to the crosslinking structure of the adhesive layer itself.

Examples of the polyfunctional crosslinking agent having an isocyanate group include dimethylsilyl diisocyanate, methylsilyl triisocyanate, tetraisocyanate silane, phenylsilyl triisocyanate and ethoxysilane. Silicon isocyanate compounds such as triisocyanate, 2,4-tolylene diisocyanate, paraphenylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate Or a diisocyanate compound such as block type isocyanate [for example, Coronate 250 manufactured by Nippon Polyurethane Industry Co., Ltd.]
7, ibid. 2513, ibid. 2515, etc.].

As the polyfunctional crosslinking agent having an epoxy group, 1,3-bis (NN-diglycidylaminomethyl) cyclohexanone, diglycidyl orthotoluidine, N, N, N ', N'-tetraglycidyl m There are glycidyl amine compounds such as xylene diamine, neopentyl glycol diglycidyl ether, and glycidyl ether compounds such as 1,6-hexanediol diglycidyl ether.

Examples of the polyfunctional crosslinking agent having an aziridine group include trimethylolpropane tris [3- (1-aziridinyl) propionate] and trimethylolpropane tris [3- (1- (2-methyl) azide]. Aziridine compounds such as lysinylpropionate)].

The amount of these polyfunctional crosslinking agents used is usually 0.001 per 100 parts by weight of the acrylic polymer.
To 5 parts by weight, preferably 0.01 to 2 parts by weight. If the amount added is too small, sufficient interlayer adhesion cannot be obtained, and if too large, crosslinking of the adhesive layer proceeds too much and sufficient adhesive properties cannot be obtained.

The adhesive layer is formed by a photopolymerization-based method (hereinafter referred to as method A) or a polymerization-based method other than photopolymerization including solution polymerization ( Hereinafter, it will be referred to as method B). In some cases, the above-mentioned methods A and B may be combined appropriately.

In the method A, a composition for photopolymerization containing the above-mentioned monomer and a photopolymerization initiator is prepared, and the composition is coated on a release paper, and then ultraviolet rays of about 400 to 2,000 mj / cm ² are applied. By irradiating and photopolymerizing, the adhesive layer is formed at the same time as the synthesis of the acrylic polymer. In order to facilitate coating, the composition for photopolymerization may be previously irradiated with a small amount of ultraviolet rays, and a part thereof may be polymerized to increase the viscosity.
When a polyfunctional crosslinking agent is used, it is usually added after the partial polymerization and reacted.

In the method B, for example, in the solution polymerization method, the above-mentioned monomer and a thermal polymerization initiator such as benzoylperoxide are used to carry out solution polymerization by a conventional method to obtain a solution of an acrylic polymer. After coating the release paper with the solution, heating and drying is usually performed at 100 to 130 ° C. If a polyfunctional crosslinking agent is used, it is added to the above solution. Further, a monomer containing a reactive functional group or a functional group containing active hydrogen may be added to the above solution to further polymerize it during heating and drying.

Examples of the photopolymerization initiator used in Method A include benzoin ethers such as benzoin methyl ether and benzoin isopropyl ether, and anizoin methyl ether.
Substituted benzoin ethers such as Ter, 2,2-diethoxyacetophenone, 2,2-Dimethoxy-2-phenone Substituted acetophenones such as acetophenone, and 2-methyl-2-hydroxypropionenone Substitution-α
-Ketols, aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride, and 1-phenone-
There are photoactive oximes such as 1,1-propanedione-2- (o-ethoxycarbonyl) oxime.

The photopolymerization initiator of the method A and the thermal polymerization initiator of the method B are both in the range of usually 0.01 to 4 parts by weight, preferably 0.1 to 100 parts by weight of the above-mentioned monomer.
Used in the range of up to 3 parts by weight.

In forming the adhesive layer by the method A and the method B, in order to improve the cohesive force of the adhesive layer, a crosslinkable monomer having two or more monoethylenically unsaturated groups in one molecule.
May be added to the composition or polymer solution for photopolymerization. The addition amount is preferably 1% by weight or less based on the total amount of the monomer, and if the amount is too much, excessive crosslinking will result and the adhesive properties will be deteriorated.

Examples of the crosslinkable monomer include polyethylene glycol di (meth) acrylate and pentaerythritol.
Luge (meth) acrylate, trimethylol propane tri (meth) acrylate, hexanediolgeol (meth)
Examples thereof include acrylate, epoxy acrylate, urethane acrylate and the like.

If desired, various additives such as a chain transfer agent, a thickener, a thixotropic agent, and a filler may be added to the photopolymerization composition or polymer solution. Chain transfer agents include alkyl mercaptans, thioglycolic acid, and diphenyl sulfides. Thickeners include chloroprene rubber and acrylic rubber. Fillers include inorganic compounds such as calcium carbonate, clay, and silica. There are fillers, inorganic hollow bodies such as glass balun and silas balun, organic hollow bodies such as acrylic balun and vinylidene chloride balun, and plastic beads.

The adhesive layer thus obtained has a monomer polymerization rate of 70% by weight or more, preferably 90% by weight or more, from the viewpoint of shape retention. When the polymerization rate is less than the above value, the solid content concentration (polymer base) is adjusted to be the above value or more by means such as heat drying. If the solid content concentration is too low, it is difficult to handle the adhesive layer, and the workability in the subsequent steps deteriorates. The thickness of the adhesive layer is not particularly limited, but is usually 25 to 1,000.
The thickness is 0 μm, preferably about 100 to 500 μm.

In the present invention, two adhesive layers of the same kind or different kinds obtained as described above are then laminated via a photocurable composition layer which is liquid at room temperature. This stack is
Since the composition layer is liquid at room temperature, good adhesion can be achieved without the need for a special device such as a laminator. Moreover, since the two adhesive layers are prepolymerized and have a good shape-retaining property, there is no problem if they are mixed with each other at the interface with the composition layer.

The photocurable composition layer that is liquid at room temperature used here is polymerized and cured by irradiation with light such as ultraviolet rays, and causes a crosslinking reaction at the interface with the adhesive layer. When R contains a reactive functional group, a functional group containing active hydrogen may be contained, and when the layer contains a functional group containing active hydrogen, it may contain a reactive functional group. It does not matter whether or not it exhibits adhesiveness after photocuring. In the case of forming a relatively soft photo-curable layer, the adhesiveness of the two adhesive layers gives a good result, while in the case of forming a relatively hard photo-curable layer, the adhesive force can be increased. Depending on the composition, it can be useful for improving the interlayer strength and the adhesive property.

From the viewpoint of compatibility with two adhesive layers containing an acrylic polymer as a main component, a composition containing a (meth) acrylic acid alkyl ester as a main component and a photopolymerization initiator added thereto is preferable. At that time, a monomer having an active hydrogen-containing functional group or a reactive functional group is introduced to introduce the functional group or reactive group.
A polyfunctional crosslinking agent is used. Further, if necessary, various additives such as a crosslinkable monomer and other chain transfer agents, thickeners, thixotropic agents, and fillers may be added.

The types and amounts of these monomers, polyfunctional crosslinking agents, photopolymerization initiators and various additives are almost the same as in the case of the acrylic polymer for the adhesive layer. It can be appropriately set according to the characteristics required for the photocured layer.

In order to interpose such a photocurable composition layer between two adhesive layers, one adhesive layer may be coated and then the other adhesive layer may be superposed on the coated surface. . In order to facilitate the coating, a small amount of light such as ultraviolet rays may be previously irradiated, and a part thereof may be photopolymerized to increase the viscosity. The total coating thickness of the two adhesive layers is usually 100 to 5,000 μm, preferably 200 to
It is preferable that the thickness is about 3,000 μm.

After laminating the two adhesive layers in this way, 400 to 2,000 mj /
The photocurable composition layer interposed between the adhesive layers is photocured by irradiating with ultraviolet rays of about cm ² . At the same time as this photo-curing, and further by aging at room temperature or under heating thereafter, a functional group containing active hydrogen and a reactive functional group are formed at the interface between the photo-curing layer and the two adhesive layers. Cause a bridge reaction. The residual monomer after the photo-curing and crosslinking reaction is 5% by weight or less, preferably 1% by weight or less.

In order to carry out the crosslinking reaction quickly, a catalyst can be added in advance. Examples of the catalyst include amines such as triethylamine, triethylenediamine, dimethylaminonityl acrylate and diethylaminoethyl acrylate, metal salts such as stannic chloride, ferric chloride and antimony trichloride, and dibutyltin dilaurate. Examples thereof include organic metal compounds such as sodium salt, tetra (2-ethylhexyl) titanate, and sodium orthophenylphenate.

These catalysts may be added to either of the two adhesive layers or the photocurable composition layer, but are preferably added to the adhesive layer side. The amount of these catalysts used is
For example, when it is added to the adhesive layer side, the amount is usually 0.01 to 5 parts by weight with respect to 100 parts by weight of the monomer constituting this layer.

The pressure-sensitive adhesive tape thus obtained has a multi-layer structure consisting of an adhesive layer, a photo-curing layer and an adhesive layer, and each layer is chemically and firmly bonded by a crosslinking reaction. Therefore, it exhibits excellent shear resistance without being easily peeled off between layers.

[0043]

As described above, according to the method of the present invention,
Two adhesive layers with acrylic polymer as the main component can be laminated with great bond strength without using special equipment such as laminator, without disturbing the layers, and with good workability and economical efficiency. Therefore, in the case where the two adhesive layers have different adhesive properties, the two properties can be used as they are and the two types of adherends can be successfully adhered and fixed.

If the two adhesive layers are of the same type,
By setting the thickness and composition of the photocurable layer, the adhesive properties such as the adhesive force and cohesive force of the entire tape can be adjusted arbitrarily. In particular, when the photocurable layer is thickened, the above-mentioned adhesive property is improved, so that the desired adhesive property according to the type of adherend can be obtained by adjusting the thickness.

[0045]

EXAMPLES Next, as an example of the present invention, a mode in which the two adhesive layers are of the same type will be described more specifically. Hereinafter, "parts" means "parts by weight". Further, the adhesive force and the shear holding force are measured by the following methods.

<Adhesive Strength> According to JIS Z-1522, a stainless steel plate was used as an adherend for measurement. The unit is g / 20 mm width.

<Shear holding power> 10 mm double-sided adhesive tape
Cut into a size of 10 mm and attach the other ends of two aluminum plates with this adhesive tape. One aluminum plate was fixed, and a load of 500 g was applied to the other aluminum plate in the horizontal direction of the adhesive tape and the plate was left in an atmosphere of 40 ° C., and the time until the aluminum plate dropped was measured.

Example 1 90 parts of n-butyl acrylate, 10 parts of acrylic acid, 0.4 parts of benzoylperoxide and 210 parts of toluene were charged into a flask and the system was sufficiently replaced with nitrogen gas. Solution polymerization was performed by heating and stirring at 80 ° C. to obtain an acrylic polymer solution having a viscosity of 160 poise, a polymerization rate of 98% by weight, and a solid content concentration of 36% by weight.

Into this acrylic polymer solution, tetraglycidyl-1,3-bisaminomethylcyclohexane 1.
While mixing 5 parts, this is coated on a release-treated polyester film and heat-treated at 100 ° C. for 15 minutes in a hot-air dryer to promote the reaction of the above polyfunctional crosslinking agent, Volatile components mainly consisting of toluene were removed by evaporation. This gives a solids content of 97% by weight and a thickness of 50%.
μm film-like adhesive layer (hereinafter referred to as adhesive film A1
I got).

Separately from this, n-butyl acrylate 90
Parts, 10 parts of acrylic acid, and 0.2 parts of 2,2-dimethoxy-2-phenylacetophenone were irradiated with a small amount of ultraviolet rays with a high-pressure mercury lamp to partially photopolymerize the composition. 1 part of trimethylolpropane triacrylate as a crosslinkable monomer and 2,2-dimethoxy-2-
A photocurable composition which is liquid at room temperature by mixing with 0.1 part of phenylacetophenone (hereinafter referred to as liquid composition B1)
Got

Next, two sheets of the above-mentioned adhesive film A1 were prepared, one of which was coated with the above liquid composition B1, and the other adhesive film A1 was superposed on the coated surface. The coating amount of the liquid composition B1 was such that the total thickness of the entire laminate including the two adhesive films A1 was 200 μm.
After being laminated in this way, the liquid composition B1 was photopolymerized by irradiating ultraviolet rays from one side with a high pressure mercury lamp. As a result, a pressure-sensitive adhesive tape having a solid content of 97% by weight was obtained.

Example 2 98 parts of 2-ethylhexyl acrylate, 2 acrylic acid
And 0.2 part of 2,2-dimethoxy-2-phenylacetophenone were irradiated with a small amount of ultraviolet rays with a high pressure mercury lamp to partially polymerize the composition. To this, 10 parts of 2-hydroxyethyl acrylate and 0.1 part of trimethylolpropane triacrylate as a crosslinkable monomer were mixed, and then coated on a release-treated polyester film. By further irradiating with ultraviolet light in a nitrogen gas atmosphere to perform photopolymerization, a film-like adhesive layer (hereinafter referred to as adhesive film A2) having a solid content of 95% by weight and a thickness of 50 μm was obtained.

Separately, 90 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid and 2,2-dimethoxy-
A composition comprising 0.2 part of 2-phenylacetophenone was partially photopolymerized by irradiating it with a small amount of ultraviolet rays from a high pressure mercury lamp, and then 1,6-hexanedio- was added as a polyfunctional crosslinking agent. 2 parts of diglycidyl ether, 0.5 part of trimethylolpropane triacrylate as a crosslinkable monomer, and 0.1 part of 2,2-dimethoxy-2-phenylacetophenone are mixed. Thus, a photocurable composition that was liquid at room temperature (hereinafter, referred to as liquid composition B2) was obtained.

Next, two sheets of the above-mentioned adhesive film A2 were prepared, one of which was coated with the above liquid composition B2, and the other adhesive film A2 was superposed on the coated surface. The coating amount of the liquid composition B2 was such that the total thickness of the entire laminate including the two adhesive films A2 was 200 μm.
After being laminated in this way, the liquid composition B2 was photopolymerized by irradiating ultraviolet rays from one side with a high pressure mercury lamp. As a result, a pressure-sensitive adhesive tape having a solid content of 98% by weight was obtained.

Example 3 90 parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid
Parts, benzoylperoxide 0.4 parts and toluene 210 parts were charged in a flask and the system was sufficiently replaced with nitrogen gas, and then solution polymerization was carried out by heating and stirring at 60 to 80 ° C., and the viscosity was 100 poises. An acrylic polymer solution having a polymerization rate of 98% by weight and a solid content concentration of 30% by weight was obtained.

To the acrylic polymer solution, 1.7 parts of 1,6-hexamethylene diisocyanate as a polyfunctional crosslinking agent was mixed with 100 parts of its solid content, and this was subjected to a mold release treatment. Was coated on the above polyester film and heat-treated at 100 ° C. for 15 minutes in a hot-air dryer to promote the reaction of the above polyfunctional crosslinking agent and to volatilize and remove volatile components mainly of toluene. . As a result, a film-like adhesive layer having a solid content of 95% by weight and a thickness of 50 μm (hereinafter referred to as an adhesive film A3) was obtained.

Next, two sheets of the above-mentioned adhesive film A3 were prepared, one of which was coated with the liquid composition B1 prepared in Example 1, and the coated surface was overlaid with the other adhesive film A3. The coating amount of the liquid composition B1 was such that the total thickness of the entire laminate including the two adhesive films A3 was 200 μm. After being laminated in this way, the liquid composition B1 was photopolymerized by irradiating ultraviolet rays from one side with a high pressure mercury lamp. As a result, a pressure-sensitive adhesive tape having a solid content of 98% by weight was obtained.

Comparative Example 1 The acrylic polymer solution obtained in Example 1 was mixed with 100 parts of the solid content of trimethylol as a crosslinkable monomer.
0.1 parts of propane acrylate triacrylate and 0.5 parts of benzoylperoxide are mixed and coated on a polyester film which has been subjected to a mold release treatment.
By heat treatment at 00 ° C. for 15 minutes, the volatile components mainly including toluene were removed by volatilization along with the reaction of the above-mentioned crosslinkable monomer.

The solid content thus obtained was 94% by weight,
Two film-like adhesive layers having a thickness of 50 μm (hereinafter referred to as adhesive film A4) were prepared, and one of them was used in Example 1
The liquid composition B1 prepared in 1. was applied, and the other adhesive film A4 was overlaid on the applied surface. The coating amount of the liquid composition B1 was such that the total thickness of the entire laminate including the two adhesive films A4 was 200 μm. After being laminated in this way, the liquid composition B1 was photopolymerized by irradiating ultraviolet rays from one side with a high pressure mercury lamp. As a result, a pressure-sensitive adhesive tape having a solid content of 95% by weight was obtained.

Comparative Example 2 90 parts of n-butyl acrylate, 10 parts of acrylic acid, 2,
A composition consisting of 0.2 parts of 2-dimethoxy-2-phenylacetophenone was irradiated with a small amount of ultraviolet rays with a high pressure mercury lamp to partially photopolymerize it. To this, 1 part of trimethylolpropane triacrylate as a crosslinkable monomer,
2,2-dimethoxy-2-phenylacetophenone 0.
After mixing with 1 part, it is coated on a polyester film which has been subjected to a mold release treatment, and further irradiated with ultraviolet rays in a nitrogen gas atmosphere to perform photopolymerization, so that the solid content is 98% by weight,
A film-like composition layer having a thickness of 100 μm was obtained.

Next, the adhesive film A1 obtained in Example 1
Was prepared, and the above-mentioned film-shaped composition layer was interposed between both films, and laminated and pressure-bonded by a laminator roll to obtain a pressure-sensitive adhesive tape.

Comparative Example 3 85 parts of n-butyl acrylate, 15 parts of ethyl acrylate
And 0.2 part of 2,2-dimethoxy-2-phenylacetophenone were irradiated with a small amount of ultraviolet rays with a high pressure mercury lamp to partially polymerize the composition. In addition to this, trimethylolpropane triacrylate 1 as a crosslinkable monomer
And 0.1 part of 2,2-dimethoxy-2-phenylacetophenone were mixed to obtain a photocurable composition that was liquid at room temperature (hereinafter referred to as liquid composition B3).

Next, the adhesive film A1 obtained in Example 1
Was prepared, one of which was coated with the above liquid composition B3, and the other adhesive film A1 was superposed on the coated surface. The coating amount of the liquid composition B3 is two adhesive films A
The total thickness of the entire laminate including No. 1 was set to 200 μm. After being laminated in this way, the liquid composition B3 was photopolymerized by irradiating ultraviolet rays from one side with a high pressure mercury lamp. As a result, a pressure-sensitive adhesive tape having a solid content of 93% by weight was obtained.

The pressure-sensitive adhesive tapes produced in the above Examples 1 to 3 and Comparative Examples 1 to 3 were examined for adhesive force and shear holding force. The results are shown in Table 1 below. In the table, * means that the anchor was broken at the interface between the adhesive layer and the photocurable layer.

[0065]

[Table 1]

As is clear from the results shown in Table 1 above, the pressure-sensitive adhesive tapes shown in Examples 1 to 3 of the present invention are liquid at room temperature in which two adhesive layers are interposed between the two layers. Due to the photo-curing of the photo-curable composition layer and the bridging reaction between the functional groups at the interface between the photo-curing layer and the adhesive layer, a strong bond is formed, resulting in excellent shearing. It can be seen that this indicates the holding power.

On the other hand, even when a photocurable composition layer which is liquid at room temperature is interposed between two adhesive layers to be photocured, the photocurable layer and the adhesive layer have an interface at the interface. Comparison using pressure-sensitive adhesive tapes shown in Comparative Examples 1 and 3 in which no bridging reaction between functional groups occurs, and a film-like material preliminarily photocured in place of the photocurable composition layer which is liquid at room temperature. It can be seen that the pressure-sensitive adhesive tape of Example 2 is inferior in shear holding force because the bonding strength between the adhesive layer and the photocurable layer is weak.

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Claims (2)

[Claims] 1. An adhesive layer mainly comprising a (meth) acrylic acid alkyl ester-based polymer is laminated via a photocurable composition layer which is liquid at room temperature, and then the above composition layer is formed. Photocuring, and at the interface between the photocuring layer and the two adhesive layers, a crosslinking reaction is caused by the active hydrogen-containing functional group and the reactive functional group to form an adhesive layer-photocuring layer-adhesion. A method for producing a pressure-sensitive adhesive tape, which comprises obtaining a pressure-sensitive adhesive tape having a multilayer structure composed of an agent layer. 2. The method for producing a pressure-sensitive adhesive tape according to claim 1, wherein the reactive functional group is an isocyanate group, an epoxy group or an aziridine group, and the active hydrogen-containing functional group is a hydroxyl group or a carboxyl group. .