JPH07100784B2 - Adhesive composition and adhesive tape or sheet using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive composition that constitutes a pressure-sensitive adhesive layer such as a pressure-sensitive adhesive tape or a pressure-sensitive adhesive sheet, and more specifically, a base such as a pressure-sensitive adhesive tape or a pressure-sensitive adhesive sheet. In the case where the material film layer or the adherend to be attached is composed mainly of a vinyl chloride resin softened by the addition of a plasticizer (hereinafter referred to as soft vinyl chloride resin), the above-mentioned substrate The present invention relates to an acrylic pressure-sensitive adhesive layer that does not cause a decrease in adhesive strength due to the plasticizer in the film layer or the plasticizer in the adherend.

The present invention also relates to an adhesive tape or sheet comprising a base film layer containing a soft vinyl chloride resin as a main component and an acrylic adhesive layer.

(Prior Art) Usually, a rubber adhesive and an acrylic adhesive are used as this type of adhesive. Rubber adhesives include natural rubber, NBR (acrylonitrile-butadiene rubber), SBR
The main component is a synthetic rubber such as (styrene-butadiene rubber) and a tackifying resin, and the acrylic pressure-sensitive adhesive contains an acrylic acid ester copolymer as a main component. These pressure sensitive adhesives are used by themselves for adhesion of adherends, and are used in the form of pressure sensitive adhesive tapes or pressure sensitive adhesive sheets or sheets held on a base material, or double-sided pressure sensitive adhesive tapes whose both sides are covered 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 a pressure sensitive adhesive sheet is attached thereto, a soft vinyl chloride resin plate containing a plasticizer is used. In the case of joining with a double-sided adhesive tape, the plasticizer in the resin migrates over time to the adhesive itself or the adhesive layer of the adhesive tape, the adhesive sheet or the surface adhesive tape, which significantly increases the adhesive performance of the adhesive. There is a problem that it can be lowered. Even when a tape or sheet made of a soft vinyl chloride resin containing a plasticizer is used as a base material for the adhesive tape or sheet, the same problem as described above is caused by migration of the plasticizer.

Conventionally, as a countermeasure for the decrease in adhesiveness due to the migration of the plasticizer, an acrylic adhesive has been disclosed in, for example, JP-A-53-94519.
JP-A No. 1-10
In many cases such as using a crosslinkable monomer and a metal complex in the adhesive as described in 1384 or mixing nitrified cotton with the adhesive as described in JP-A-63-230783. Research has been done and attempts have been made to improve adhesives.

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

Therefore, as described in JP-A-56-136871 and JP-B-64-9352, a primer is first applied to the surface of a soft vinyl chloride resin product as an adherend, and an adhesive is applied on the primer. A method of applying or applying an adhesive tape has been proposed and put into practical use. But this method
In other words, the pressure-sensitive adhesive cannot withstand practical use unless a primer is also used, and therefore an extra step of applying the primer is required. In addition, for example, it is very difficult to apply the primer evenly to the surface of the adherend made of a soft vinyl chloride resin having a large area at the time of construction outdoors.

(Problems to be Solved by the Invention) From the above points, there has been a strong demand for a pressure-sensitive adhesive that can prevent a decrease in the pressure-sensitive adhesive force due to the migration of a plasticizer without using a primer.

In order to meet this demand, an object of the present invention is to provide a soft vinyl chloride-based resin when a substrate such as a pressure-sensitive adhesive tape or a pressure-sensitive adhesive sheet or an adherend to be attached is made of a soft vinyl chloride-based resin containing a plasticizer. Another object of the present invention is to provide an acrylic pressure-sensitive adhesive capable of effectively suppressing a decrease in the pressure-sensitive adhesive force and holding power due to the transfer of a plasticizer from a resin to the pressure-sensitive adhesive, and a pressure-sensitive adhesive tape or sheet using the same.

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

In addition, various acrylic adhesives were attached to soft vinyl chloride resins such as dioctyl phthalate, and the extent to which the plasticizer in the resin transferred to the adhesive was measured. It has been found that the pressure-sensitive adhesive as a monomer surely lowers the saturated absorption amount of the plasticizer in the pressure-sensitive adhesive layer as compared with the pressure-sensitive adhesive as a main monomer containing 2-ethylhexyl acrylate or isooctyl acrylate.

Further, various monomers were copolymerized with butyl (meth) acrylate, and the saturated absorption amount of the plasticizer in the pressure-sensitive adhesive layer composed of the obtained copolymer was measured. Saturation absorption does not decrease significantly when using highly polar monomers such as acid, maleic anhydride, itaconic acid, and vinyl acetate, and only when using methyl (meth) acrylate or ethyl (meth) acrylate It has been found that the amount of absorption is significantly reduced.

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

That is, the pressure-sensitive adhesive composition according to the present invention comprises 40% by weight or more of butyl (meth) acrylate and 10% of methyl (meth) acrylate and / or ethyl (meth) acrylate.
To 30% by weight and 3 to 30% by weight of N-vinylpyrrolidone as the main component of the copolymer
It is characterized in that 5 to 50 parts by weight of a plasticizer is added to 100 parts by weight.

The pressure-sensitive adhesive tape or sheet according to the present invention is a pressure-sensitive adhesive tape or sheet comprising a base film layer containing a vinyl chloride resin containing a plasticizer as a main component and an acrylic pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive is butyl. 40% by weight or more of (meth) acrylate and 10 to 30% by weight of methyl (meth) acrylate and / or ethyl (meth) acrylate
And an acrylic copolymer containing 3 to 30% by weight of N-vinylpyrrolidone as a main component, and 5 to 50 parts by weight of a plasticizer is added to 100 parts by weight of the copolymer. And the monodeal.

(I) A typical acrylic pressure-sensitive adhesive has a low-polarity and low glass transition temperature monomer such as butyl (meth) acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate as a main monomer, and (meth) Acrylic acid, itaconic acid, maleic acid and other highly polar α, β
It has a structure in which a copolymer containing an unsaturated carboxylic acid as a cohesive force-imparting component is contained as a main component, and the above-mentioned highly polar monomer is used as a reaction point to crosslink with a required crosslinking agent. Acrylic acid in particular has good compatibility and reactivity with the acrylic monomer, and it is easy to balance the basic three physical properties of the adhesive such as adhesive strength (that is, peeling strength), holding power and tack, It is a monomer that is frequently used in acrylic pressure-sensitive adhesives because it has good reactivity and a suitable cross-linking pressure-sensitive adhesive can be obtained and is inexpensive.

The feature of the present invention is that N-vinylpyrrolidone is required without substantially using α, β unsaturated carboxylic acid having reactive active hydrogen as described above as a cohesive force imparting component constituting an acrylic polymer. Acrylic copolymer containing a required amount of butyl (meth) acrylate as a main monomer and a required amount of methyl (meth) acrylate and / or ethyl (meth) acrylate copolymerized therewith The point is that an acrylic pressure-sensitive adhesive is used, which is mainly composed of a coalesce and to which a required amount of a plasticizer is added to the copolymer.

Butyl (meth) acrylate as the main monomer has low polarity and low glass transition temperature. Butyl (meta)
The content of acrylate is limited to the range of 40% by weight or more. The reason is that if the content is less than 40% by weight, the pressure-sensitive adhesive becomes too hard and the pressure-sensitive adhesive strength decreases. Particularly preferred content of butyl (meth) acrylate is 50% by weight
That is all.

The content of methyl (meth) acrylate and / or ethyl (meth) acrylate copolymerized with butyl (meth) acrylate is limited to the range of 10 to 30% by weight. The reason is that if the content is less than 10% by weight, the cohesive force is low, and conversely if the content is more than 30% by weight, the adhesive physical properties cannot be balanced. Methyl (meta)
A particularly preferred content of acrylate and / or ethyl (meth) acrylate is in the range of 20 to 30% by weight.

The content of N-vinylpyrrolidone is limited to the 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 there is a phenomenon that the adhesive remains on the adherend when peeled off. This is because if the amount is large, the adhesive becomes hard and loses its adhesive strength at low temperatures. A particularly preferred content of N-vinylpyrrolidone is in the range of 5 to 20% by weight.

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

When the plasticizer gradually migrates from the adherend or substrate film containing soft vinyl chloride resin as the main component to the adhesive layer, the migration of the plasticizer finally reaches the concentration equilibrium, The amount of plasticizer is saturated. Since this process is a diffusion process, if a plasticizer is mixed in advance with the pressure-sensitive adhesive layer before attaching the pressure-sensitive adhesive layer to the adherend or substrate film, the migration of the plasticizer occurs immediately and the concentration equilibrium occurs. It will be in the same state as what it has 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 the conventional pressure-sensitive adhesive composition, the equilibrium was biased toward the pressure-sensitive adhesive side, and the plasticizer concentration in the pressure-sensitive adhesive was higher than that in the soft vinyl chloride resin.

On the other hand, in the acrylic pressure-sensitive adhesive of the present invention, butyl acrylate is used as the main monomer, and methyl (meth) acrylate and / or ethyl (meth) acrylate is copolymerized therewith to change the concentration equilibrium state. The concentration of the plasticizer in the pressure-sensitive adhesive can be made equal to or less than the concentration in the soft vinyl chloride resin. The pressure-sensitive adhesive of this composition can maintain a high pressure-sensitive adhesive strength as compared with the conventional pressure-sensitive adhesive even when it is stuck to the soft vinyl chloride resin for a long time because the saturated concentration of the plasticizer that migrates is low. .

The addition amount of the plasticizer is limited to the range of 5 to 50 parts by weight with respect to 100 parts by weight of the acrylic copolymer. The reason is that if the addition amount is less than 5 parts by weight based on 100 parts by weight of the acrylic copolymer, the above concentration equilibrium cannot be obtained, and conversely 50 parts by weight based on 100 parts by weight of the copolymer. This is because the cohesive strength becomes low when the content exceeds the range. A particularly suitable amount of the plasticizer added is in the range of 10 to 30 parts by weight based on 100 parts by weight of the acrylic copolymer.

(Iii) The acrylic polymer can be further copolymerized by dissolving butyl acrylate and methyl (meth) acrylate and / or ethyl (meth) acrylate and N-vinylpyrrolidone in required amounts in a suitable solvent and further copolymerizing them as required. It is prepared by adding a required amount of such an unsaturated monomer, adding a polymerization initiator, and raising the temperature of the mixed solution to carry out a polymerization reaction. The polymerization reaction is practically carried out by solution polymerization. In this case, the reaction solvent is generally an ester such as methyl acetate or ethyl acetate; benzene, toluene,
Examples thereof include aromatic hydrocarbons such as xylene; alicyclic hydrocarbons such as cyclohexane; ketones such as acetone and methyl ethyl ketone. These are used alone or in combination as appropriate. As a polymerization method, in addition to solution polymerization, any method such as emulsion polymerization and suspension polymerization can be carried out. As the polymerization initiator, various peroxides such as benzoyl peroxide and lauryl peroxide,
Known polymerization initiators such as azo compounds such as azobisisobutyronitrile may be appropriately applied alone or in combination. These are usually 0.01 to 1 with respect to 100 parts by weight of the monomer.
Used in parts by weight.

The molecular weight of the acrylic copolymer is not particularly limited, but the polystyrene reduced weight average molecular weight by gel permeation chromatography is 100,000 to 1,000,000, and preferably 300,000 to 70.
In many cases.

Acrylic copolymer is for the purpose of maintaining the physical properties of the pressure-sensitive adhesive even at high temperature, enhancing the cohesive force and cohesive force for highly polar adherends such as vinyl chloride resin, and increasing the cohesive force of double-sided tape. , Preferably cross-linked. As the cross-linking agent, a cross-linking agent such as an isocyanate compound, an epoxy compound or an organic metal complex is used. Cross-linking
It is carried out by a known method such as an electron beam irradiation method, a thermal crosslinking method using a peroxide such as benzoyl peroxide as a catalyst, or a curing method using an isocyanate crosslinking agent. In the case of crosslinking with an isocyanate-based crosslinking agent, 0.1 to 1% of a main monomer is copolymerized with a monomer serving as a crosslinking origin such as 2-hydroxy (meth) acrylate. When using α, β unsaturated carboxylic acid as the crosslinking origin monomer, the amount used is preferably as small as possible, 0.5 wt% or less,
It is preferably 0.1% by weight or less.

In the pressure-sensitive adhesive according to the present invention, in addition to the acrylic copolymer,
If necessary, a tackifying resin such as a xylene resin, a phenol-modified xylene resin, a phenol resin, a chroman resin, a rosin or a rosin-modified resin may be added. The addition amount of the tackifying resin is 0 to 30 parts by weight based on 100 parts by weight of the acrylic copolymer.

(Iv) The base film layer of the pressure-sensitive adhesive tape or sheet according to the present invention contains a soft vinyl chloride resin as a main component and does not have to have a specific composition or shape. This resin contains, for example, a vinyl chloride resin having a degree of polymerization of 500 to 2000 (may be a copolymer containing 80% or more of vinyl chloride) as a main component, a stabilizer, a plasticizer, a pigment,
It may contain a filler or the like. As the plasticizer, a non-migratory but low-molecular plasticizer such as dioctyl phthalate or dioctyl adipate may be used without particularly using an expensive polyester polymer plasticizer. The thickness of the substrate film is preferably 0.03 ~ 0.5μ
m.

As the form of the pressure-sensitive adhesive tape or sheet of the present invention, as shown in the attached FIG. 1, one having a pressure-sensitive adhesive layer (2) formed on one side of a base film layer (1), as shown in FIG. In the embodiment shown in FIG. 1, an undercoat layer (4) is interposed between the base film layer (1) and the adhesive layer (2), as shown in FIG. An undercoating agent layer (4) formed on the other surface of the base film layer (1). As shown in FIG. 4, the pressure-sensitive adhesive layer (2) is separated from the base film layer (1) and the release paper. Sandwiched in (3), as shown in FIG. 5, an undercoat layer (4) is provided between the base film layer (1) and the pressure-sensitive adhesive layer (2) in the form of FIG. As shown in FIG. 6, the release agent layer (5) is formed on the other surface of the base film layer (1) as shown in FIG. Things, as shown in FIG. 7,
In the embodiment shown in FIG. 6, there is a base film layer (1) and a release agent layer (5) in which an undercoat layer (4) is interposed.

(Operation) (i) Since the pressure-sensitive adhesive composition according to the present invention includes an acrylic copolymer containing a required amount of N-vinylpyrrolidone, an adherend or a base film layer is added to the acrylic copolymer. Even if the plasticizer is transferred from the plasticizer, the adhesive strength and the holding power are not or hardly reduced by the plasticizer.

The reason for this is not clear, but it is considered as follows.

In the conventional pressure-sensitive adhesives containing a copolymer containing α, β-unsaturated carboxylic acid containing active hydrogen as a cohesive force-imparting component, the plasticizer may migrate into the pressure-sensitive adhesive or soft chloride. When it accumulates at the interface with vinyl resin, the adhesive strength and holding power will decrease, so the cause of this performance deterioration is that the functional groups such as carboxyl groups having active hydrogen are modified. it is conceivable that.

On the other hand, in the pressure-sensitive adhesive of the present invention, α-β unsaturated carboxylic acid having reactive active hydrogen as described above is not substantially used as a cohesive force imparting component, and N-vinylpyrrolidone is used in a required amount. Therefore, it is considered that there is no room for the above-mentioned transformation, and therefore the adhesive force and the holding force do not decrease even if the plasticizer migrates.

(Ii) Since the pressure-sensitive adhesive of the present invention uses butyl (meth) acrylate as the main monomer, it is more plastic than the pressure-sensitive adhesive having 2-ethylhexyl acrylate or isooctyl acrylate as the main monomer. The saturated absorption of the agent is small. The reason is considered to be due to the difference in compatibility with the plasticizer. That is, it has 8 carbon atoms like 2-ethylhexyl acrylate and isooctyl acrylate.
Adhesives whose main monomer is a monomer having about 4 alkyl groups are more dioctyl phthalate and diisononyl than adhesives whose main monomer is butyl (meth) acrylate having an alkyl group with 4 carbon atoms. 8 carbon atoms like phthalate
It is considered to have good compatibility with a plasticizer having 9 alkyl chains.

However, even if the main monomer butyl (meth) acrylate is copolymerized with a large amount of highly polar monomer to increase the polarity of the entire pressure-sensitive adhesive, the saturated absorption amount of the plasticizer does not significantly decrease, and the main monomer Only when the body is copolymerized with methyl (meth) acrylate or ethyl (meth) acrylate, the saturated absorption amount is remarkably reduced.

(Iii) In the pressure-sensitive 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 substrate film containing soft vinyl chloride resin as the main component to the adhesive layer, the migration of the plasticizer finally reaches the concentration equilibrium, The amount of plasticizer is saturated. Since this process is a diffusion process, if a plasticizer is mixed in advance with the adhesive before attaching the adhesive layer to the adherend or substrate film, the plasticizer will migrate immediately and reach a concentration equilibrium. It will be in the same state as what you did. 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 the conventional pressure-sensitive adhesive composition, the equilibrium is biased toward the pressure-sensitive adhesive side, and the plasticizer concentration in the pressure-sensitive adhesive was higher than that in the soft vinyl chloride resin, but in the acrylic pressure-sensitive adhesive of the present invention, as the main monomer, By using butyl acrylate and copolymerizing it with methyl (meth) acrylate and / or ethyl (meth) acrylate, the concentration equilibrium state is changed, and the plasticizer concentration in the pressure-sensitive adhesive is changed to that in the soft vinyl chloride resin. It can be equal or less. The pressure-sensitive adhesive of this composition can maintain a high pressure-sensitive adhesive strength as compared with the conventional pressure-sensitive adhesive even when it is stuck to the soft vinyl chloride resin for a long time because the saturated concentration of the plasticizer that migrates is low. .

Also, if you add a plasticizer to the adhesive like this,
Since the concentration equilibrium is reached at a concentration lower than that of 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 low molecular weight plasticizer with migration properties, and the most remarkable effect is the addition of a low molecular weight plasticizer with migration properties. It is obtained when the amount is large, that is, when 40 parts or more of the plasticizer is contained with respect to 100 parts of the vinyl chloride resin.

(Examples) Next, the performance test of each pressure-sensitive adhesive will be shown by giving reference examples relating to the measurement of the transfer amount of the plasticizer, examples of the present invention, and some comparative examples to be compared therewith.

Reference Example 1 In a reactor equipped with a thermometer, a stirrer and a dropping funnel, 94 parts by weight of butyl acrylate as a monomer for copolymerization and 6 parts by weight of itaconic acid were dissolved in 100 parts by weight of ethyl acetate, and polymerization was initiated in this solution. 0.2 parts by weight of benzoyl peroxide was added as an agent. This mixture is placed under nitrogen reflux for 8 hours.
Polymerization reaction was carried out by stirring at 0 ° C. for 8 hours to obtain a pressure-sensitive adhesive solution.

After adding 1.0 part by weight of an isocyanate cross-linking agent (trade name "Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd.) to this pressure-sensitive adhesive solution, the resulting coating solution was dried on a release paper so that the thickness after drying was 70 μm. And was dried at a temperature of 100 ° C. for 5 minutes. Thus, an adhesive sheet was 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 the copolymerization monomer.

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

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 monomers for copolymerization.

Reference Example 5 As a copolymerization monomer, butyl acrylate 69.5 parts by weight, ethyl acrylate 30 parts by weight and acrylic acid 0.5
A pressure-sensitive adhesive sheet was prepared in the same manner as in Reference Example 1, except that parts by weight were used.

Reference Example 6 As a copolymerization monomer, 69.5 parts by weight of butyl acrylate, 30 parts by weight of methyl acrylate and 0.5 parts of acrylic acid
A pressure-sensitive adhesive sheet was prepared in the same manner as in Reference Example 1, except that parts by weight were used.

Reference Example 7 79.5 parts by weight of butyl acrylate, 20 parts by weight of methyl methacrylate and 0.
An adhesive sheet was prepared in the same manner as in Reference Example 1, except that 5 parts by weight was used.

Reference Example 8 A pressure-sensitive adhesive sheet was prepared in the same manner as in Reference Example 1, 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 the monomers for copolymerization. .

Measurement of transfer amount of plasticizer Sample pieces of each adhesive sheet (25 mm ×
50 mm) is a sheet material (30 mm × 60 mm × 5 mm) made of a soft vinyl chloride resin having the composition shown in Table 1 as an adherend, which is attached to this to promote aging in a 90 ° C atmosphere for 1 week and a plasticizer Was transferred. After that, the pressure-sensitive adhesive was peeled off, and the migration amount of the plasticizer was measured by the weight method, and this value was taken as the saturated absorption amount of the plasticizer. The results are summarized in Table 1.

In Table 1, the saturated adsorption amount is the weight fraction of the plasticizer in the adhesive, and the measured SP value (solubility parameter) is the Japan Adhesive Association Journal.
It was obtained by the method of Fedors et al. Described in Vol. 22, p. 564 (1986).

As is clear from Table 1, the saturated absorption amount of the plasticizer in the pressure-sensitive adhesive does not correlate with the SP value. In addition, in the case of the sample piece of Reference Example 2, although the saturated absorption amount was decreased, when 25 parts by weight of acrylic acid was copolymerized with 75 parts by weight of butyl acrylate, the glass transition was such that the pressure-sensitive adhesive property at room temperature disappeared. This test piece is not preferable because the temperature rises.

As a result, it can be seen that the polar monomers that can be applied as an adhesive and have a plasticizer are only methyl (meth) acrylate and ethyl (meth) acrylate as shown in Reference Examples 5, 6 and 7.

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

This adhesive solution was applied to a polyester film with a thickness of 38μ so that the layer thickness after drying would be 70μ, and the temperature was 100 ° C.
Allow to dry for minutes. Then, the obtained layer was irradiated with an electron beam for crosslinking to prepare an adhesive tape having a crosslinked adhesive layer.

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

Example 3 65 parts by weight of butyl acrylate as a monomer for copolymerization,
An adhesive tape was prepared in the same manner as in Example 1 except that 5 parts by weight of vinylpyrrolidone, 10 parts by weight of methyl methacrylate and 20 parts by weight of ethyl acrylate were used, and 50 parts by weight of dioctyl phthalate was used.

Example 4 As a monomer for copolymerization, 79.8 parts by weight of butyl acrylate, 10 parts by weight of vinylpyrrolidone, 10 parts of ethyl acrylate
Parts by weight and 0.2 parts by weight of 2-hydroxyethyl acrylate, 10 parts by weight of dioctyl phthalate, and 0.5 parts by weight of an isocyanate-based crosslinking agent (trade name "Coronate HL" manufactured by Nippon Polyurethane Co., Ltd.) were used for crosslinking. The same operation as in Example 1 was performed to prepare an adhesive tape.

Comparative Example 1 30 parts by weight of butyl acrylate as a monomer for copolymerization,
30 parts by weight of vinyl pyrrolidone and 40 parts of ethyl acrylate
A pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, except that 60 parts by weight of dioctyl phthalate was used.

Comparative Example 2 A pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, 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 the monomers for copolymerization. Prepared.

Comparative Example 3 85 parts by weight of butyl acrylate as a monomer for copolymerization,
An adhesive tape was prepared in the same manner as in Example 1, except that 10 parts by weight of vinylpyrrolidone and 5 parts by weight of acrylic acid were used.

Comparative Example 4 Isooctyl acrylate 59.7 as a monomer for copolymerization
Example 4 except that parts by weight, 35 parts by weight of vinylpyrrolidone, 5 parts by weight of acrylic acid and 0.3 parts by weight of 2-hydroxyethyl acrylate were used, 30 parts by weight of dioctyl phthalate and 0.6 parts by weight of an isocyanate cross-linking agent were used.
A pressure-sensitive adhesive tape was prepared in the same manner as in.

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 so that the thickness after drying would be 70μ, and the temperature was 100 ° C.
Allow to dry for minutes. Then, the obtained coating layer was irradiated with an electron beam to crosslink.

Next, the pressure-sensitive adhesive thus obtained was transferred to a base film having a thickness of 200 μm and made of a soft vinyl chloride resin having the composition shown in Table 2. Thus, the adhesive tape was prepared.

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

Example 7 65 parts by weight of butyl acrylate as a monomer for copolymerization,
An adhesive tape was prepared in the same manner as in Example 5, except that 5 parts by weight of vinylpyrrolidone, 10 parts by weight of methyl acrylate and 20 parts by weight of ethyl acrylate were used, and 50 parts by weight of dioctyl phthalate was used.

Example 8 As a monomer for copolymerization, 79.8 parts by weight of butyl acrylate, 10 parts by weight of vinylpyrrolidone, 10 parts of ethyl acrylate
Parts by weight and 0.2 parts by weight of 2-hydroxyethyl acrylate, 10 parts by weight of dioctyl phthalate, and 0.5 parts by weight of an isocyanate-based crosslinking agent (trade name "Coronate HL" manufactured by Nippon Polyurethane Co., Ltd.) were used for crosslinking. In the same manner as in Example 5, an adhesive tape was prepared.

Comparative Example 5 30 parts by weight of butyl acrylate as a monomer for copolymerization,
30 parts by weight of vinyl pyrrolidone and 40 parts of ethyl acrylate
An adhesive tape was prepared in the same manner as in Example 5, except that 60 parts by weight of dioctyl phthalate was used.

Comparative Example 6 A pressure-sensitive adhesive tape was prepared in the same manner as in Example 5, 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 the copolymer monomer. Prepared.

Comparative Example 7 85 parts by weight of butyl acrylate as a monomer for copolymerization,
An adhesive tape was prepared in the same manner as in Example 5, except that 10 parts by weight of vinylpyrrolidone and 5 parts by weight of acrylic acid were used.

Comparative Example 8 Isooctyl acrylate 59.7 as a monomer for copolymerization
Example 8 except that parts by weight, 35 parts by weight of vinylpyrrolidone, 5 parts by weight of acrylic acid and 0.3 parts by weight of 2-hydroxyethyl acrylate were used, 30 parts by weight of dioctyl phthalate and 0.6 parts by weight of an isocyanate crosslinking agent were used.
A pressure-sensitive adhesive tape was prepared in the same manner as in.

Performance Test (A) 1) Adhesive Strength (Peeling Force) Test The adhesive tapes prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to a 180 ° peeling test according to JIS Z0237. That is, adhesive tape test piece (25 mm x
125 mm) on the soft vinyl chloride resin plate shown in Table 2 above.
The roller was pressed back and forth once with a kg roller. Then attach 20
After 180 minutes, the above 180 ° peel test was conducted.

The pressure-sensitive adhesive tape was aged for 1 week in an atmosphere at a temperature of 90 ° C. to transfer the plasticizer in the base film into the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape. In this state, a 180 ° peel test of the adhesive tape was performed according to JIS Z0237 to measure the change in peel force.

2) Holding power test Adhesive tape test pieces were attached to the adherend by the same procedure as above to promote aging, and then 1 kg at a temperature of 80 ° C according to JIS Z0237.
A holding force test was performed using a weight, and the time until the adhesive tape was peeled from the adherend and dropped was measured. In this test, a 15 mm × 25 mm adhesive tape test piece was used.

The results of each test are summarized in Table 3.

In Table 3, ⊚ means excellent, and × means not good.

As is apparent from Table 3, the pressure-sensitive adhesive according to the present invention is superior to the conventional pressure-sensitive adhesives in all aspects of the adhesive strength after heat aging, the holding power, and the stability over time.

Performance Test (B) 1) Adhesive Strength (Peeling Force) Test Regarding the adhesive tapes prepared in Examples 5-8 and Comparative Examples 5-8, a prescribed stainless steel plate was used in place of the soft vinyl chloride resin plate, and other The point was subjected to the same operation as in 1) of the performance test (A), and a 180 ° peel test of the adhesive tape was carried out in accordance with JIS Z0237 to measure the change in peel force.

2) Holding power test Adhesive tape test pieces were attached to the adherend by the same procedure as above to promote aging, and then 1 kg at a temperature of 80 ° C according to JIS Z0237.
A holding force test was performed using a weight, and the time until the adhesive tape was peeled from the adherend and dropped was measured. In this test, a 15 mm × 25 mm adhesive tape test piece was used.

The results of each test are summarized in Table 4.

In Table 4, ⊚ and x have the same meaning as in Table 3.

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

(Effect of the invention) Since the pressure-sensitive adhesive composition according to the present invention is configured as described above, the base film layer such as a pressure-sensitive adhesive tape, a pressure-sensitive adhesive sheet or the adherend to be stuck is a soft soft vinyl chloride. When it is made of a system resin, it is possible to effectively suppress the decrease of the adhesive force and the holding force due to the transfer of the plasticizer from the soft vinyl chloride resin to the adhesive.

[Brief description of drawings]

1 to 7 are sectional views showing the forms of the adhesive tape or sheet of the present invention. (1) ... Base film layer, (2) ... Adhesive layer,
(3) ... Release paper, (4) ... Undercoat layer, (5) ... Release agent layer.

Claims (2)

[Claims] 1. An acryl comprising 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. A pressure-sensitive adhesive composition comprising a copolymer as a main component, and 5 to 50 parts by weight of a plasticizer per 100 parts by weight of the copolymer. 2. A pressure-sensitive adhesive tape or sheet comprising a base film layer containing a vinyl chloride resin containing a plasticizer as a main component, and an acrylic pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive is 40 wt% of butyl (meth) acrylate. % Or more, methyl (meth) acrylate and / or ethyl (meth) acrylate 10 to 30% by weight, and N-vinylpyrrolidone 3 to 30% by weight as the main component, An adhesive tape or sheet, characterized in that 5 to 50 parts by weight of a plasticizer is added to 100 parts by weight of the coalescence.