JPH04175356A - Self-adhesive composition and self-adhesive tape or sheet prepared therefrom - Google Patents

Abstract

PURPOSE:To prepare a self-adhesive compsn. causing no degradation in the adhesion to or holding of an adherend comprising a plasticized polyvinyl chloride resin by compounding a specific acrylic copolymer with a specified amt. of a plasticizer. CONSTITUTION:100 pts.wt. acrylic copolymer comprising 40wt.% or higher butyl (meth)acrylate, 10-30wt.% methyl (meth)acrylate and/or ethyl (meth) acrylate, and 3-30wt.% N-vinylpyrrolidone is compounded with 5-50 pts.wt. plasticizer (e.g. dioctyl phthalate).

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an adhesive composition constituting an adhesive layer of an adhesive tape, an adhesive sheet, etc. When the material film layer or the adherend to which it is attached is mainly composed of vinyl chloride resin softened by the addition of a plasticizer (hereinafter referred to as soft vinyl chloride resin), the above base material The present invention relates to an acrylic pressure-sensitive adhesive layer that does not cause a decrease in adhesive strength due to a plasticizer in a film layer or a plasticizer in an adherend.

The present invention also relates to an adhesive tape or sheet comprising a base film layer mainly composed of a soft vinyl chloride resin and an acrylic adhesive layer.

(Prior Art) Rubber adhesives and acrylic adhesives are usually used as this type of adhesive. Rubber adhesives include natural rubber, NBR (acrylonitrile-butadiene rubber),
The main components are synthetic rubber such as SBR (styrene-butadiene rubber) and a tackifying resin, and the acrylic adhesive is mainly composed of an acrylic acid ester copolymer. These adhesives can be used by themselves to bond adherends, or they can be held in layers on a base material and used in the form of adhesive tapes or adhesive sheets, or double-sided adhesive tapes covered on both sides with release paper. It is used in the form of

By the way, when a soft vinyl chloride resin product containing a plasticizer is used as an adherend and the adhesive itself is applied or an adhesive tape or adhesive sheet is attached to the adherend, a soft vinyl chloride resin plate containing a plasticizer is also applied. When bonding with double-sided adhesive tape, the plasticizer in the resin migrates over time to the adhesive itself or to the adhesive layer of the adhesive tape, adhesive sheet, or surface-adhesive tape, which significantly reduces the adhesive performance of the adhesive. The problem is that it can be degraded.

Even when a tape or sheet made of a soft vinyl chloride resin containing a plasticizer is used as a base material for an adhesive tape or adhesive sheet, the same problem caused by plasticizer migration as described above occurs.

Conventionally, as a countermeasure against the decrease in adhesiveness due to plasticizer migration, for acrylic adhesives, for example, Japanese Patent Laid-Open No. 53-945
Mixing a resol-type phenolic resin with an adhesive as described in Japanese Patent Publication No. 1989, or using a resin that imparts adhesion with an adhesive as described in Japanese Patent Application Laid-open No. 58-1.0972,
As described in JP-A No. 1-101384, a cross-linking monomer and a metal complex are used together in an adhesive, and JP-A-1-101384
As described in Japanese Patent No. 230783, many studies have been conducted to improve adhesives, such as mixing nitrified cotton with adhesives.

However, in recent years, with the expansion of applications such as adhesive tape,
The performance required for this has also increased, and it has been difficult to solve the above-mentioned problems caused by plasticizer migration only by improving the adhesive as described above.

Therefore, Japanese Patent Application Publication No. 56-136871 and Japanese Patent Publication No. 64
As described in Publication No. 9352, a primer is first applied to the surface of a soft vinyl chloride resin product to be an adherend,
A method of applying adhesive or pasting adhesive tape on top of the brimer has been proposed and put into practical use. However, in other words, this method is not practical unless the adhesive is used in combination with a primer, and therefore an extra step of applying a primer is required. Furthermore, for example, during outdoor on-site construction, it is extremely difficult to evenly apply the brimer to the surface of a large area of soft vinyl chloride resin adherend.

(Problems to be Solved by the Invention) From the above points, there has been a strong desire for an adhesive that can prevent a decrease in adhesive strength caused by plasticizer migration without using a primer.

The purpose of the present invention is to meet this demand, and when the base material of an adhesive tape or adhesive sheet or the adherend to which it is attached is made of a soft vinyl chloride resin containing a plasticizer, An object of the present invention is to provide an acrylic adhesive that can effectively suppress a decrease in adhesive strength and holding power due to transfer of plasticizer from a resin to an adhesive, and an adhesive tape or sheet using the same.

(Means for Solving the Problems) The present inventors synthesized copolymers consisting of various acrylic monomers, and measured the adhesion of the obtained acrylic adhesives to soft vinyl chloride resins. As a result, we found that N-vinylpyrrolidone exerts an extremely excellent effect as a cohesive force imparting component.As a result of further investigation, we surprisingly found that if the content of active hydrogen-containing monomers such as acrylic acid is small, It was found that the smaller the value, the more suppressed is the decrease in adhesive strength after plasticizer migration.

In addition, when various acrylic adhesives were attached to soft vinyl chloride resins such as dioctyl phthalate and the extent to which the plasticizer in the resin migrated to the adhesive was measured, it was found that butyl (meth)acrylate was the main component. It has been found that the saturation absorption amount of plasticizer in the adhesive layer is definitely lower when using a monomer-based adhesive than when using an adhesive whose main monomer is 2-ethylhexyl acrylate or isooctyl acrylate. .

Furthermore, we copolymerized butyl (meth)acrylate with various monomers and measured the saturated absorption amount of plasticizer in the adhesive layer made of the resulting copolymer. When using acids, highly polar monomers such as maleic anhydride, itaconic acid, and vinyl acetate, the saturated absorption amount does not decrease much, and methyl (meth)acrylate, ethyl (
It has been found that the saturated absorption amount is significantly reduced only when meth)acrylate is used.

The present invention has been made based on the above-mentioned findings.

That is, the adhesive composition according to the present invention contains 40% by weight or more of butyl (meth)acrylate and 1% or more of methyl (meth)acrylate and/or ethyl (meth)acrylate.
The main component is an acrylic copolymer containing 0 to 30% by weight and 3 to 30% by weight of N-vinylpyrrolidone, and 5 to 50 parts by weight of a plasticizer is added to 100 parts by weight of the copolymer. It is characterized by the fact that

Further, the adhesive tape or sheet according to the present invention is an adhesive tape or sheet consisting of a base film layer mainly composed of a vinyl chloride resin containing a plasticizer and an acrylic adhesive layer, in which the adhesive is made of butyl chloride. 40% by weight or more of (meth)acrylate and 10-30% of methyl (meth)acrylate and/or ethyl (meth)acrylate
% by weight, and an acrylic copolymer comprising 3 to 30% by weight of N-vinylpyrrolidone, the copolymer 1
A monodeal characterized in that 5 to 50 parts by weight of a plasticizer is added to 00 parts by weight.

(T) Normal acrylic adhesive is butyl (meth)
The main monomers are monomers with low polarity and low glass transition temperature such as acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate, and (meth)acrylic acid,
Reactive highly polar α such as itaconic acid and maleic acid,
It has a structure in which the main component is a copolymer containing β-unsaturated carboxylic acid as a cohesive force-imparting component, and is crosslinked with a required crosslinking agent using the above-mentioned highly polar monomer as a reaction site. In particular, acrylic acid has good compatibility and reactivity with the above-mentioned acrylic monomers, and it is easy to balance the three basic physical properties of adhesives, such as adhesive strength (i.e., peeling force), holding power, and tack, and it is compatible with the above-mentioned crosslinking agent. It is a monomer often used in acrylic adhesives because of its good reactivity, the ability to obtain suitable crosslinked adhesives, and its low cost.

The feature of the present invention is that the cohesive force imparting component constituting the acrylic copolymer does not substantially use α,β unsaturated carboxylic acid having reactive active hydrogen as described above, and N-vinylpyrrolidone is used instead. An acrylic copolymer containing the required amount of butyl (meth)acrylate as the main monomer and the required amount of methyl (meth)acrylate and/or ethyl (meth)acrylate to be copolymerized therewith. The key point is that an acrylic pressure-sensitive adhesive is used, which has a polymer as its main component, and a required amount of plasticizer is added to the copolymer.

Butyl (meth)acrylate, which is the main monomer, has low polarity and a low glass transition temperature. Butyl (meth)
The content of acrylate is limited to a range of 40% by weight or more. The reason for this is that if the content is less than 40% by weight, the adhesive becomes too hard and its adhesive strength decreases. A particularly preferred content of butyl (meth)acrylate is 50% by weight or more.

The content of methyl (meth)acrylate and/or ethyl (meth)acrylate copolymerized with butyl (meth)acrylate is limited to a range of 10 to 30% by weight. The reason for this is that if the content is less than 10% by weight, the cohesive force will be low, whereas if the content is more than 30% by weight, the adhesive physical properties will not be balanced.

A particularly preferred content of methyl (meth)acrylate and/or ethyl (meth)acrylate is in the range from 20 to 30% by weight.

The content of N-vinylpyrrolidone is limited to a range of 3 to 30% by weight. The reason for this is that when this content is less than 3% by weight, the cohesive force of the adhesive decreases and the adhesive remains on the adherend when it is peeled off. This is because if the amount is too high, the adhesive becomes hard and loses its adhesive strength at low temperatures. A particularly preferred content of N-vinylpyrrolidone is in the range from 5 to 20% by weight.

(100) The acrylic pressure-sensitive adhesive of the present invention contains 5 to 50 parts by weight of a plasticizer per 100 parts by weight of the acrylic copolymer. The reason for this is as follows.

When the plasticizer gradually migrates from the adherend or base film mainly composed of soft vinyl chloride resin to the adhesive layer, the plasticizer migration eventually reaches a concentration equilibrium, and the concentration of the plasticizer in the adhesive increases. The amount of plasticizer is saturated. Since this process is a diffusion process,
If a plasticizer is mixed in the adhesive before applying the adhesive layer to the adherend or the base film, the plasticizer will immediately migrate and the state will be the same as when the concentration equilibrium has been reached. The plasticizer concentration in this equilibrium state depends on the plasticizer concentration in the soft vinyl chloride resin and the composition of the adhesive.

In conventional adhesive compositions, the equilibrium was shifted toward the adhesive, and the concentration of plasticizer in the adhesive was higher than the concentration in the soft vinyl chloride resin.

In contrast, the acrylic adhesive of the present invention uses butyl acrylate as the main monomer and copolymerizes it with methyl (meth)acrylate and/or ethyl (meth)acrylate, thereby changing the concentration equilibrium state. The concentration of plasticizer in the adhesive can be made equal to or lower than the concentration in the soft vinyl chloride resin.

Even if an adhesive with this composition is attached to a soft vinyl chloride resin for a long period of time, the saturation concentration of migrating plasticizer is low, so it can maintain higher adhesive strength than conventional adhesives. .

The amount of plasticizer added is limited to 5 to 50 parts by weight per 100 parts by weight of the acrylic copolymer. The reason for this is that if the amount added is less than 5 parts by weight per 100 parts by weight of the acrylic copolymer, the concentration equilibrium state described above cannot be obtained; This is because the cohesive force decreases when the amount exceeds 100%. A particularly preferable addition amount of the plasticizer is 10 to 100 parts by weight of the acrylic copolymer.
The range is 30 parts by weight.

(iii) The acrylic copolymer is prepared by dissolving the required amounts of butyl acrylate, methyl (meth)acrylate and/or ethyl (meth)acrylate and N-vinylpyrrolidone in a suitable solvent, and further copolymerizing as necessary. It is prepared by adding a required amount of a possible unsaturated monomer, adding a polymerization initiator, raising the temperature of the mixture, and carrying out a polymerization reaction. The polymerization reaction is practically carried out by solution polymerization. In this case, the reaction solvent generally includes esters such as methyl acetate and ethyl acetate; aromatic hydrocarbons such as benzene, toluene, and xylene; alicyclic hydrocarbons such as cyclohexane; and ketones such as acetone and methyl ethyl ketone. , these may be used alone or in combination as appropriate. In addition to solution polymerization, any method such as emulsion polymerization and suspension polymerization can be used as the polymerization method. Further, as the polymerization initiator, known polymerization initiators such as various peroxides such as benzoyl peroxide and lauryl peroxide, and azo compounds such as azobisisobutyronitrile can be appropriately used alone or in combination. These are usually 0.00 parts per 100 parts by weight of monomer.
It is used in a proportion of 0.01 to 1 part by weight.

The molecular weight of the acrylic copolymer is not particularly limited, but the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography is 100,000 to 1,000,000, preferably 30
It is between 10,000 and 700,000.

Acrylic copolymers are used to maintain the physical properties of adhesives even at high temperatures, enhance adhesive strength and cohesive force to highly polar adherends such as vinyl chloride resin, and increase the cohesive force of double-sided tapes. , preferably crosslinked. As the crosslinking agent, a crosslinking agent such as an isocyanate compound, an epoxy compound, or an organometallic complex is used.

Crosslinking is performed by known methods such as electron beam irradiation, thermal crosslinking using a peroxide such as peroxide as a catalyst, and curing using an isocyanate crosslinking agent. In the case of crosslinking using an isocyanate crosslinking agent, 2
- Copolymerize 0.1 to 1% of a monomer serving as a crosslinking starting point such as hydroxy (meth)acrylate with the main monomer.

When using α, β unsaturated carboxylic acid as a crosslinking starting point monomer, it is better to use as little amount as possible, and 0
．． It is 5% by weight or less, preferably 0.1% by weight or less.

In addition to the acrylic copolymer, the adhesive according to the present invention includes:
A tackifier resin such as xylene resin, phenol-modified xylene resin, phenol resin, chroman resin, rosin or rosin-modified resin may be added as necessary. The amount of tackifying resin added is 100% of the acrylic copolymer.
The amount is 0 to 30 parts by weight.

(iv) The base film layer of the adhesive tape or sheet according to the present invention contains a soft vinyl chloride resin as a component, and does not need to have a specific formulation or shape. This resin has a polymerization degree of 500 to 20, for example.
00 vinyl chloride resin (may be a copolymer containing 80% or more of vinyl chloride) as the main component, and may also contain stabilizers, plasticizers, pigments, fillers, etc. As the plasticizer, there is no need to use a non-migratory but expensive polyester polymer plasticizer, but a migratory low-molecular plasticizer such as dioctyl phthalate-1 and dioctyl adipate may be used. The thickness of the base film is preferably 0.
．． 03 to 0.5 μm.

The adhesive tape or sheet of the present invention may be in the form of an adhesive layer (2) formed on one side of a base film layer (1) as shown in the attached Figure 1, or as shown in Figure 2. , a structure in which an undercoat layer (4) is interposed between a base film layer (1) and an adhesive layer (2) in the form shown in FIG.
As shown in the figure, in the form shown in Fig. 2, an undercoat layer (4) is also formed on the other side of the base film layer (1), and as shown in Fig. 4, an adhesive layer (2) is formed on the other side of the base film layer (1). ) is sandwiched between the base film layer (1) and the release paper (3), as shown in Figure 5. In the configuration shown in Figure 4, the base film layer (1) and the adhesive layer ( Primer layer (4) between 2)
As shown in FIG. 6, a mold release agent layer (5) is formed on the other side of the base film layer (1) in the form of FIG. 4, as shown in FIG. As shown in FIG. 6, the base film layer (1) and the release agent layer (5)
There is one in which an undercoat layer (4) is interposed between the layers.

(Function) (j) The adhesive composition according to the present invention contains a required amount of N-
Since it contains an acrylic copolymer containing vinylpyrrolidone, even if plasticizer migrates from the adherend or base film layer, the adhesive strength and holding power will be reduced by the plasticizer. There is nothing or very little to be done.

Although the reason for this is not clear, it is thought to be as follows.

With conventional adhesives that are mainly composed of copolymers containing α,β-unsaturated carboxylic acids containing active hydrogen as a cohesive force imparting component, plasticizers migrate into the adhesive and soft chloride When it accumulates at the interface with the vinyl resin, the adhesive force and holding power decrease, and the reason for this decrease in performance is the phenomenon in which functional groups such as carboxyl groups that have active hydrogen are denatured. it is conceivable that.

On the other hand, the adhesive of the present invention substantially uses α,β unsaturated carboxylic acid having a reactive active hydrogen as described above as a cohesive force imparting component, and uses a required amount of N-vinylpyrrolidone. Therefore, there is no room for the above-mentioned metamorphosis to occur, and therefore it is thought that even if the plasticizer migrates, the adhesive strength and holding power will not decrease.

(fD) The adhesive of the present invention has butyl (
Since it uses meth)acrylate, the saturated amount of plasticizer absorbed is smaller than that of adhesives whose main monomers are 2-ethylhexyl acrylate, isooctyl acrylate, or the like. The reason for this is thought to be due to the difference in compatibility with plasticizers. In other words, adhesives whose main monomer is a monomer having an alkyl group of about 8 carbon atoms, such as 2-ethylhexyl acrylate and isooctyl acrylate, are based on butyl (butyl) having an alkyl group of about 4 carbon atoms. Meta)
Adhesives with 8 carbon atoms such as dioctyl phthalate and diisononyl phthalate are better than adhesives with acrylate as the main monomer.
It is believed to have good compatibility with plasticizers having ~9 alkyl chains.

However, even if the main monomer butyl (meth)acrylate is copolymerized with a large amount of a highly polar monomer to increase the polarity of the entire adhesive, the saturated absorption amount of the plasticizer does not decrease significantly, and the main monomer A significant decrease in saturated absorption occurs only when methyl (meth)acrylate or ethyl (meth)acrylate is copolymerized with the polymer.

(iiD) In the adhesive composition according to the present invention, 5 to 50 parts by weight of a plasticizer is added to 100 parts by weight of the acrylic copolymer.The action of the plasticizer is as follows.

When the plasticizer gradually migrates from the adherend or base film mainly composed of soft vinyl chloride resin to the adhesive layer, the plasticizer migration eventually reaches a concentration equilibrium, and the concentration of the plasticizer in the adhesive increases. The amount of plasticizer is saturated. Although this process is a diffusion process,
If a plasticizer is mixed with the adhesive in advance before applying the adhesive layer to the adherend or base film, the plasticizer will immediately migrate and the state will be the same as when the concentration equilibrium has been reached. The plasticizer concentration in this equilibrium state depends on the plasticizer concentration in the soft vinyl chloride resin and the composition of the adhesive.

In conventional adhesive compositions, the equilibrium was shifted toward the adhesive side, and the concentration of plasticizer in the adhesive was higher than that in the soft vinyl chloride resin, but in the acrylic adhesive of the present invention, as the main monomer, Butyl acrylate was used, and methyl (
By copolymerizing meth)acrylate and/or ethyl(meth)acrylate, the concentration equilibrium state can be changed and the plasticizer concentration in the adhesive can be made equal to or lower than the concentration in the flexible vinyl chloride resin. . Even if an adhesive with this composition is attached to a soft vinyl chloride resin for a long period of time, the saturation concentration of migrating plasticizer is low, so it can maintain higher adhesive strength than conventional adhesives. .

Also, if you add a plasticizer to the adhesive like this,
Since concentration equilibrium is reached at a lower concentration than conventional products, the total amount of plasticizer added can be reduced and higher adhesive strength can be obtained. The effect of reducing the amount of plasticizer added is particularly large when the plasticizer in the soft vinyl chloride resin is a migratory low-molecular plasticizer, and the most noticeable effect is the addition of a migratory low-molecular plasticizer. If the amount is large, that is, vinyl chloride resin 100
It is obtained when the plasticizer is contained in 40 parts or more per part.

(Example) Next, a reference example regarding the −j determination of the amount of plasticizer transferred, an example of the present invention, and some comparative examples to be compared with this will be listed, and performance tests of each adhesive will be shown.

Reference Example 1 In a reactor equipped with a thermometer, a stirrer, and a dropping funnel, 94 parts by weight of butyl acrylate and 6 parts by weight of itaconic acid as comonomers for copolymerization were dissolved in 100 parts by weight of ethyl acetate, and polymerization was added to this solution. 0.2 parts by weight of benzoyl peroxide was added as an initiator. This mixed solution was stirred at 80° C. for 8 hours under nitrogen reflux to carry out a polymerization reaction to obtain an adhesive solution.

After adding 1.0 parts by weight of an isocyanate-based crosslinking agent (trade name "Coronate L" manufactured by Nippon Polyurethane Co., Ltd.) to this adhesive solution, the resulting coating solution was separated so that the thickness after drying was 70μ. It was applied onto a paper pattern and dried at a temperature of 100°C for 5 minutes. A pressure-sensitive adhesive sheet was thus prepared.

Reference Example 2 A pressure-sensitive adhesive sheet was prepared in the same manner as in Reference Example 1, except that 75 parts by weight of butyl acrylate and 25 parts by weight of acrylic acid were used as copolymerization monomers.

Reference Example 3 Isooctyl acrylate 94 as a monomer for copolymerization
A pressure-sensitive adhesive sheet was prepared in the same manner as in Reference Example 1 except that 25 parts by weight and 25 parts by weight of itaconic acid were used.

Reference Example 4 A pressure-sensitive adhesive sheet was prepared in the same manner as in Reference Example 1, except that 94 parts by weight of 2-ethylhexyl acrylate and 6 parts by weight of itaconic acid were used as copolymerization monomers.

Reference Example 5 The same operation as in Reference Example 1 was performed except that 69.5 parts by weight of butyl acrylate, 30 parts by weight of ethyl acrylate, and 0.5 parts by weight of acrylic acid were used as monomers for copolymerization. A sheet was prepared.

Reference Example 6 The same operation as in Reference Example 1 was performed except that 69.5 parts by weight of butyl acrylate, 30 parts by weight of methyl acrylate, and 0.5 parts by weight of acrylic acid were used as monomers for copolymerization. A sheet was prepared.

Reference Example 7 The same operation as in Reference Example 1 was performed except that 79.5 parts by weight of butyl acrylate, 20 parts by weight of methyl methacrylate, and 0.5 parts by weight of acrylic acid were used as monomers for copolymerization. A sheet was prepared.

Reference Example 8 The same operation as in Reference Example 1 was performed except that 69.5 parts by weight of butyl acrylate, 30 parts by weight of vinyl acetate, and 0.5 parts by weight of acrylic acid were used as monomers for copolymerization. A sheet was prepared.

Measurement of the amount of plasticizer transfer A sample piece (25 m
m x 50 mm) was attached to a plate (30 mm x 60 mm x 5 mm) made of a soft vinyl chloride resin with the formulation shown in Table 1 as an adherend, and aging was accelerated for one week in an atmosphere at a temperature of 90°C to transfer the plasticizer. . Thereafter, the adhesive was peeled off, and the amount of plasticizer transferred was measured by gravimetric method, and this value was taken as the saturated absorption amount of plasticizer. The results are summarized in Table 1.

(Leaving space below) Table 1 In Table 1, the saturated adsorption amount is the weight fraction of the plasticizer in the adhesive, and the calculated SP value (solubility parameter) is from the Japan Adhesive Association Journal Vo 1.22, page 564 (1986 It was determined by the method of Fedors et al. described in ).

As is clear from Table 1, the saturated absorption amount of plasticizer in the adhesive does not correlate with the SP value. In addition, in the case of the sample piece of Reference Example 2, although a decrease in the saturated absorption amount is observed, when 25 parts by weight of acrylic acid is copolymerized with 75 parts by weight of butyl acrylate, the glass transition is such that the pressure-sensitive adhesiveness at room temperature disappears. This test piece is not preferred because the temperature will rise.

As a result, as shown in Reference Examples 5.6 and 7, the only polar monomers that can be applied as adhesives and have a plasticizer are methyl (meth)acrylate and ethyl (meth)acrylate.

Example 1 In a reactor equipped with a thermometer, a stirrer and a dropping funnel, 70 parts by weight of butyl acrylate, 10 parts by weight of vinylpyrrolidone and 20 parts by weight of ethyl acrylate as comonomers were dissolved in 100 parts by weight of ethyl acetate. Then, 0.2 parts by weight of benzoyl peroxide was added as a polymerization initiator to this solution. This mixture was heated at 80°C under nitrogen reflux.
After stirring for 8 hours to carry out the polymerization reaction, 30 parts by weight of dioctyl phthalate was added as a plasticizer to the reaction solution,
An adhesive solution was obtained.

This adhesive solution was applied to a polyester film with a thickness of 38μ so that the layer thickness after drying was 70μ, and the temperature was 100μ.
Dry at ℃ for 5 minutes. Then, the obtained layer was crosslinked by irradiating it with an electron beam to prepare an adhesive tape having a crosslinked adhesive layer.

Example 2 An adhesive tape was prepared in the same manner as in Example 1, except that 40 parts by weight of butyl acrylate, 30 parts by weight of vinylpyrrolidone, and 30 parts by weight of methyl acrylate were used as copolymerization monomers. .

Example 3 As monomers for copolymerization, 65 parts by weight of butyl acrylate, 5 parts by weight of vinylpyrrolidone, 1 part by weight of methyl methacrylate
using 0 parts by weight and 20 parts by weight of ethyl acrylate,
An adhesive tape was prepared in the same manner as in Example 1 except that 50 parts by weight of dioctyl phthalate was used.

Example 4 As monomers for copolymerization, 79.8 parts by weight of butyl acrylate, 10 parts by weight of vinylpyrrolidone, 10 parts by weight of ethyl acrylate and 0.2 parts by weight of 2-hydroxyethyl acrylate were used, and 10 parts by weight of dioctyl phthalate. An adhesive tape was prepared in the same manner as in Example 1, except that crosslinking was carried out using 0.5 parts by weight of an isocyanate crosslinking agent (trade name: Coronate HLJ, manufactured by Nippon Polyurethane Co., Ltd.).

Comparative Example 1 The same operation as in Example 1 was carried out except that 30 parts by weight of butyl acrylate, 30 parts by weight of vinylpyrrolidone and 40 parts by weight of ethyl acrylate were used as copolymerization monomers, and 60 parts by weight of dioctyl phthalate was used. An adhesive tape was prepared.

Comparative Example 2 The same operation as in Example 1 was performed except that 90 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of vinylpyrrolidone, and 5 parts by weight of methyl acrylate were used as monomers for copolymerization. A tape was prepared.

Comparative Example 3 The same operation as in Example 1 was carried out except that 85 parts by weight of butyl acrylate, 10 parts by weight of vinyl pyrrolidone and 5 parts by weight of acrylic acid were used as monomers for copolymerization.
An adhesive tape was prepared.

Comparative Example 4 Inoctyl acrylate 59 as a copolymerization monomer
．． 7 parts by weight, 35 parts by weight of vinylpyrrolidone, 5 parts by weight of acrylic acid, and 0 parts by weight of 2-hydroxyethyl acrylate.
An adhesive tape was prepared in the same manner as in Example 4, except that 3 parts by weight of dioctyl phthalate, 30 parts by weight of dioctyl phthalate, and 0.6 parts by weight of the isocyanate crosslinking agent were used.

Example 5 The same operation as in Example 1 was performed to obtain an adhesive solution.

This adhesive solution was coated on a silicone-treated release paper to a dry thickness of 70μ and heated to 100°C.
and dried for 5 minutes. The resulting coating layer was then irradiated with an electron beam to effect crosslinking.

Next, the pressure-sensitive adhesive thus obtained was transferred onto a 200 μm thick base film made of a soft vinyl chloride resin having the formulation shown in Table 2. An adhesive tape was thus prepared.

Example 6 An adhesive tape was prepared in the same manner as in Example 5, except that 40 parts by weight of butyl acrylate, 30 parts by weight of vinylpyrrolidone, and 30 parts by weight of methyl acrylate were used as copolymerization monomers. .

Example 7 As monomers for copolymerization, 65 parts by weight of butyl acrylate, 5 parts by weight of vinylpyrrolidone, 1 part by weight of methyl methacrylate
using 0 parts by weight and 20 parts by weight of ethyl acrylate,
An adhesive tape was prepared in the same manner as in Example 5 except that 50 parts by weight of dioctyl phthalate was used.

Example 8 As monomers for copolymerization, 79.8 parts by weight of butyl acrylate, 10 parts by weight of vinylpyrrolidone, 10 parts by weight of ethyl acrylate and 0.2 parts by weight of 2-hydroxyethyl acrylate were used, and 10 parts by weight of dioctyl phthalate. An adhesive tape was prepared in the same manner as in Example 5, except that crosslinking was carried out using 0.5 parts by weight of an isocyanate crosslinking agent (trade name: Coronate HLJB, manufactured by Honpolyurethane Co., Ltd.).

Comparative Example 5 The same operation as in Example 5 was carried out except that 30 parts by weight of butyl acrylate, 30 parts by weight of vinylpyrrolidone and 40 parts by weight of ethyl acrylate were used as copolymerization monomers, and 60 parts by weight of dioctyl phthalate was used. An adhesive tape was prepared.

Comparative Example 6 The same operation as in Example 5 was performed except that 90 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of vinylpyrrolidone, and 5 parts by weight of methyl acrylate were used as monomers for copolymerization. A tape was prepared.

Comparative Example 7 The same operation as in Example 5 was carried out except that 85 parts by weight of butyl acrylate, 10 parts by weight of vinylpyrrolidone and 5 parts by weight of acrylic acid were used as monomers for copolymerization.
An adhesive tape was prepared.

Comparative Example 8 Isooctyl acrylate 59 as a copolymerization monomer
．． 7 parts by weight, 35 parts by weight of vinylpyrrolidone, 5 parts by weight of acrylic acid, and 0 parts by weight of 2-hydroxyethyl acrylate.
An adhesive tape was prepared in the same manner as in Example 8, except that 3 parts by weight of dioctyl phthalate, 30 parts by weight of dioctyl phthalate, and 0.6 parts by weight of the isocyanate crosslinking agent were used.

Table 2 Performance Test (A) 1) Adhesive Strength (Peeling Strength) Test Regarding the adhesive tapes prepared in Examples 1 to 4 and Comparative Examples 1 to 4, adhesive tape,
A 180'' peel test was conducted.

That is, an adhesive tape test piece (25 mm x 125 mm
) to the soft chlorinated vinyl resin board shown in Table 2 above.
Pressure bonding was carried out by one reciprocation of a roller of g. Then paste 2
After 0 minutes, the above 180@ peel test was performed.

In addition, the adhesive tape was aged in an atmosphere at a temperature of 90° C. for one week to transfer the plasticizer in the base film into the adhesive layer of the adhesive tape. In this state, the adhesive tape was subjected to a 180@ peel test according to JIS Z0237, and changes in peel force were measured.

2) Holding power test After applying the adhesive tape test piece to the adherend in the same manner as above to accelerate aging, a holding power test was conducted using a 1 kg weight at a temperature of 80°C in accordance with JIS 20237.
The time required for the adhesive tape to peel off from the adherend and fall was measured.

In this test, a 15 mm x 25 mm adhesive tape test piece was used.

The results of each test are summarized in Table 3.

(Margin below) Table 3 In Table 3, ◎ means excellent, and × means poor.

As is clear from Table 3, it is recognized that the adhesive according to the present invention is superior to conventional adhesives in all aspects of adhesive strength, holding power, and stability over time after heat aging.

Performance test (B) 1) Adhesive strength (peel strength) test For the adhesive tapes prepared in Examples 5 to 8 and Comparative Examples 5 to 8, a specified stainless steel plate was used instead of the soft vinyl chloride resin plate, and other Point 1 of performance test (A)
), a 180@ peel test of the adhesive tape was conducted in accordance with JIS Z0237, and changes in peel force were measured.

2) Holding power test After applying the adhesive tape test piece to the adherend using the same procedure as above to accelerate aging, a holding power test was conducted using a 1 kg weight at a temperature of 80°C in accordance with JIS Z0237.
The time required for the adhesive tape to peel off from the adherend and fall was measured.

In this test, a 15 mm x 25 mm adhesive tape test piece was used.

The results of each test are summarized in Table 4.

(Margins below) Table 4 In Table 4, the meanings of ◎ and × are the same as in Table 3.

As is clear from Table 4, the adhesive tape according to the present invention is
It is recognized that this tape is superior to conventional tapes in all aspects, including adhesive strength, holding power, and stability over time after heat aging.

(Effects of the Invention) Since the pressure-sensitive adhesive composition according to the present invention is configured as described above, the base film layer of the pressure-sensitive adhesive tape, pressure-sensitive adhesive sheet, etc. or the adherend to which it is pasted is soft and flexible. When the adhesive is made of vinyl chloride resin, it is possible to effectively suppress a decrease in adhesive strength and holding power due to transfer of plasticizer from the soft vinyl chloride resin to the adhesive.

[Brief explanation of drawings]

1 to 7 are all cross-sectional views showing the form of the adhesive tape or sheet of the present invention. (1)...Base film layer, (2)...Adhesive layer,
(3)...Release paper, (4)...Undercoat layer, (5)...
...Mold release agent layer. Patent applicant: Sekisui Chemical Co., Ltd. Figure 4

Claims (2)

[Claims] (1) 40% by weight or more of butyl (meth)acrylate;
The main component is an acrylic copolymer comprising 10 to 30% by weight of methyl (meth)acrylate and/or ethyl (meth)acrylate and 3 to 30% by weight of N-vinylpyrrolidone, and 100 parts by weight of the copolymer. 5-50 for
An adhesive composition characterized in that a weight part of a plasticizer is added. (2) An adhesive tape or sheet consisting of a base film layer mainly composed of a vinyl chloride resin containing a plasticizer and an acrylic adhesive layer, in which the adhesive contains 40% by weight or more of butyl (meth)acrylate. 10 to 30% by weight of methyl (meth)acrylate and/or ethyl (meth)acrylate, and 3 to 30% by weight of N-vinylpyrrolidone. An adhesive tape or sheet, characterized in that a plasticizer is added in an amount of 5 to 50 parts by weight.