JP5653890B2 - Water-dispersed pressure-sensitive adhesive composition and pressure-sensitive adhesive tape - Google Patents

Description

The present invention relates to a water-dispersed pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape. The water-dispersed pressure-sensitive adhesive composition of the present invention is suitable as a re-peeling pressure-sensitive adhesive, and is widely used for, for example, a surface protective film and a coating masking tape.

Conventionally, to prevent scratches, contamination, and corrosion during transportation, storage, and processing of metal and plastic products, the surface is temporarily protected, and after the above purpose has been achieved, easy and integrated peeling Surface protective films that can be used are used. Accordingly, the surface protective film is required to have an initial adhesive force that does not peel off when being applied, but is required to have an appropriate peeling force (adhesive force) that can be easily peeled off during peeling. The peeling speed in a normal peeling operation is about 10 to 50 m / min, and it is preferable that the peeling force is good in this speed region.

Acrylic pressure-sensitive adhesives are widely used in place of conventional rubber pressure-sensitive adhesives in terms of their excellent adhesive properties and weather resistance. In addition, from the viewpoint of environmental measures, resource saving, safety, etc., development of water-dispersed acrylic pressure-sensitive adhesives that do not use organic solvents has progressed, and the amount of use has also increased. There is also an example in which this water-dispersed acrylic pressure-sensitive adhesive is applied to a surface protective film. However, conventionally, water-dispersed acrylic pressure-sensitive adhesives for surface protection films tend to have an increased adhesive force due to changes over time after being attached to an adherend, requiring time for the peeling operation and removing adhesive residue. May occur. In addition, the water-dispersed acrylic pressure-sensitive adhesive used for the surface protective film has a high peeling force during high-speed peeling on a smooth surface, for example, an adherend having Ra = 0.1 μm or less, and improvement thereof has been desired. As a method for improving these, for example, there is a method of adding a peeling glaze to the pressure-sensitive adhesive, but this peeling aid may cause adherend contamination after the surface protective film is peeled off.

An object of the present invention is to provide a water-dispersed pressure-sensitive adhesive composition having a suitable initial adhesiveness and a suitable peeling force after bonding to an adherend, and a pressure-sensitive adhesive tape using the water-dispersed pressure-sensitive adhesive composition. And

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the following water-dispersed pressure-sensitive adhesive composition, and have completed the present invention.

That is, the present invention is a water-dispersed pressure-sensitive adhesive composition comprising an acrylic polymer cross-linked product (A) and a cross-linking agent (B) obtained by emulsion polymerization, wherein the acrylic polymer cross-linked product (A) Is an acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group (a) of 50% by weight or more, a methacrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group (b) of 30 to 45% by weight, a crosslinking agent ( Emulsion polymerization of a monomer compound containing 0.5 to 2.5% by weight of the functional monomer (c) not involved in crosslinking with B) and the functional monomer (d) involved in crosslinking with the crosslinking agent (B) It is related with the water dispersion-type adhesive composition characterized by the above-mentioned.

The water-dispersed pressure-sensitive adhesive composition of the present invention has a suitable initial adhesiveness and adhesion by using a monomer blend in which a specific monomer is blended at a specific ratio as a monomer blend constituting an acrylic polymer crosslinked product. It achieves an appropriate peeling force after body bonding.

The alkyl acrylate ester (a) having 4 to 12 carbon atoms in the alkyl group is the main component of the monomer blend, and is used at 50% by weight or more in the monomer blend. When the proportion of the alkyl acrylate ester (a) is small, it is not possible to obtain a good initial adhesive force and peeling force necessary for a pressure-sensitive adhesive tape. The alkyl acrylate ester (a) is preferably 53 to 65% by weight in the monomer blend.

The alkyl methacrylate having 1 to 4 carbon atoms in the alkyl group (b) is used for controlling the increase in the daily peeling force after adhering the adherend, and is 30 to 45% by weight in the monomer composition. Used. If the proportion of the alkyl methacrylate (b) is small, the peel strength after pasting of the adherend increases, so the proportion of the alkyl methacrylate (b) is 30% by weight or more, and further 35%. % Or more is preferable. On the other hand, if the ratio of the alkyl methacrylate (b) is large, the adhesive strength at the initial stage of bonding is insufficient, and the adhesive tape floats from the adherend over the past days, so that the alkyl methacrylate (b) The proportion is preferably 45% by weight or less, more preferably 43% by weight or less.

The functional monomer (c) that does not participate in crosslinking with the crosslinking agent (B) ensures the adhesion at the initial stage of bonding, and is used at 0.5 to 2.5% by weight in the monomer blend. When the proportion of the functional monomer (c) is small, the adhesiveness at the initial stage of bonding is insufficient, so the proportion of the functional monomer (c) is 0.5% by weight or more, and further 1% by weight or more. Is preferred. On the other hand, when the ratio of the functional monomer (c) is large, the daily peel strength after adhering the adherend increases, so the ratio of the functional monomer (c) is 2.5% by weight or less, and further 2 It is preferable that it is less than weight%.

The functional monomer (d) involved in cross-linking with the cross-linking agent (B) cross-links the acrylic polymer cross-linked product (A) with the cross-linking agent (B), and the aging peel strength after the adherend is bonded. It controls the rise. The ratio of the functional monomer (d) is not particularly limited as long as the water-dispersed pressure-sensitive adhesive composition is in a range that does not increase the daily peeling force and becomes a sufficient cross-linked product. The proportion of (d) is preferably 0.5% by weight or more, more preferably 1% by weight or more. On the other hand, if the ratio of the functional monomer (d) is large, if the reaction with the cross-linking agent (B) is insufficient, the residual functional groups increase, the daily peeling force increases, and even if the crosslinking is sufficiently performed When the proportion of crosslinking between the crosslinking agent (B) and the functional group in the crosslinking fraction increases as compared with the crosslinking in the polymerization stage, the reason is not clear, but the initial adhesiveness is insufficient or affixed due to the difference in the crosslinking form between the two. Since there is a case where the tape floats on the pasting date, the ratio of the functional monomer (d) is preferably 2.5% by weight or less, more preferably 2% by weight or less.

In the water-dispersed pressure-sensitive adhesive composition, it is preferable that the monomer blend is adjusted so that the obtained acrylic polymer crosslinked product (A) has a glass transition temperature of -20 to -35 ° C.

What adjusted the monomer compound so that the glass transition temperature (Tg) of acrylic polymer crosslinked material (A) may become the said range has favorable adhesiveness, and is preferable. The glass transition temperature is more preferably −23 to −32 ° C. The glass transition temperature (Tg) is generally used as follows: 1 / Tg = (W ₁ / Tg ₁ ) + (W ₂ / Tg ₂ ) + ---- (W _n / Tg) _n )
{Tg: Tg of copolymer (° K), W _n : Weight fraction of W ₁ , W ₂ --- W _n , Tg _n : Tg of polymer polymerized from each monomer (° K)} It is a value calculated from the monomer blend, and when the monomer blend contains an optional monomer other than the monomers (a) to (d), the glass transition temperature is calculated from the monomer blend containing the optional monomer. The optional monomer can be used in an appropriate amount depending on the type of each monomer within the range of less than 10% by weight of the total monomers as required.

In the water-dispersed pressure-sensitive adhesive composition, the crosslinked fraction of the acrylic polymer crosslinked product (A) is 85% by weight or more, and the crosslinked acrylic polymer crosslinked product (A) is crosslinked with the crosslinking agent (B). The cross-linking fraction is preferably 95% by weight or more.

When the cross-linking ratio of the acrylic polymer cross-linked product (A) decreases, there are many uncross-linked parts, and the cross-linking ratio does not sufficiently increase even after the addition of the cross-linking agent (B). The force increases, which is not preferable. The crosslinked fraction of the acrylic polymer crosslinked product (A) is preferably 85% by weight or more, and more preferably 87% by weight. In addition, if the cross-linking fraction of the acrylic polymer cross-linked product (A) becomes too high, the final cross-linking fraction after the addition of the cross-linking agent (B) becomes too high, resulting in insufficient initial adhesiveness or pasting time. In some cases, the tape may be lifted, and in order to prevent these problems, the crosslinked fraction of the acrylic polymer crosslinked product (A) is preferably 95% by weight or less. Moreover, it is preferable that after the acrylic polymer cross-linked product (A) is cross-linked by the cross-linking agent (B), the cross-linking fraction is 95% by weight or more, and more preferably 97% by weight or more. When the cross-linking fraction is 95% by weight or more, an increase in peel strength can be suppressed over time after being bonded to an adherend.

The said crosslinking fraction means the ratio of the crosslinking adhesive in adhesive solid content. For example, the dried pressure-sensitive adhesive solid content is wrapped with a Teflon (registered trademark) membrane having a diameter of 0.2 μm, the dissolved portion is extracted in ethyl acetate for one week at room temperature, and the cross-linking pressure-sensitive adhesive remaining in the Teflon membrane is taken out. It can be calculated by an equation.
Crosslink fraction (% by weight) = (crosslinked adhesive (g) / total adhesive (g)) × 100.

Furthermore, this invention relates to the adhesive tape in which the adhesive layer is formed on the base material with the crosslinked material of the said water dispersion type adhesive composition.

According to the water-dispersed pressure-sensitive adhesive composition of the present invention, it is possible to provide a pressure-sensitive adhesive tape excellent in moderate initial adhesiveness and stability over time. It can be easily peeled off. Further, the water-dispersed pressure-sensitive adhesive composition of the present invention does not particularly require a peeling aid, and is excellent in non-contamination to the adherend during re-peeling.

Below, the water-dispersed adhesive composition and adhesive tape containing the acrylic polymer crosslinked product (A) and the crosslinking agent (B) of the present invention will be described in detail.

Specific examples of the alkyl acrylate ester (a) having 4 to 12 carbon atoms in the alkyl group, which is the main monomer used in the preparation of the acrylic polymer crosslinked product (A), include, for example, butyl acrylate, isobutyl acrylate, acrylic Examples include pentyl acid, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, and lauryl acrylate. These acrylic acid alkyl esters (a) are used by appropriately selecting one or more of them.

Specific examples of the alkyl methacrylate (b) having 1 to 4 carbon atoms in the alkyl group include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. Etc. These methacrylic acid alkyl esters (b) are used by appropriately selecting one or more of them.

The functional monomer (c) not involved in crosslinking with the crosslinking agent (B) and the functional monomer (d) involved in crosslinking with the crosslinking agent (B) are appropriately selected depending on the functional group of the crosslinking agent (B). Select Examples of the functional group possessed by the functional monomer include a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, an epoxy group, an isocyanate group, and an aziridine group. Specific examples of the functional monomer (c) or (d) include, for example, carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, and fumaric acid; acid anhydrides such as maleic anhydride Group-containing monomer; Hydroxyl group-containing monomer such as hydroxyalkyl (meth) acrylate and glycerin di (meth) acrylate; Epoxy group-containing monomer such as glycidyl (meth) acrylate and methyl glycidyl methacrylate, aminoethyl (meth) acrylate, etc. An amino group-containing monomer, and an isocyanate group-containing monomer such as 2methacryloyloxyethyl isocyanate. The (meth) acrylic acid is acrylic acid and / or methacrylic acid, and (meth) has the same meaning in the present invention.

Among these, the reactivity with the functional group of the crosslinking agent (B) can be selected and used as appropriate. For example, combinations of reactive functional groups include a carboxyl group and an epoxy group, a carboxyl group and an aziridine group, a hydroxyl group and an isocyanate group, a carboxyl group and an oxazoline group.

In the monomer blend used for the preparation of the crosslinked acrylic polymer (A) of the present invention, other monomers that can be copolymerized may be used in combination with the above monomers, if necessary. Other copolymerizable monomers are used in a range of less than 10% by weight of the total monomers. Examples of other copolymerizable monomers include alkyl acrylates having 1 to 3 carbon atoms in alkyl groups such as methyl acrylate, ethyl acrylate, and isopropyl acrylate; alkyls such as tridecyl acrylate and stearyl acrylate. Alkyl ester having 13-18 carbon atoms; alkyl methacrylate having 5-18 carbon atoms such as isooctyl methacrylate, ethylhexyl methacrylate, tridecyl methacrylate, stearyl methacrylate, etc .; vinyl acetate, styrene , (Meth) acrylonitrile, n-vinylpyrrolidone, (meth) acryloylmorpholine, cyclohexylmaleimide, impropylmaleimide, (meth) acrylamide and the like. Other examples include polyfunctional monomers such as triethylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane tri (meth) acrylate.

The acrylic polymer crosslinked product (A) is prepared by emulsion polymerization of the monomer blend in the presence of an emulsifier. The polymerization method generally includes a batch charging method, a monomer dropping method, a monomer emulsion dropping method, etc. Among these methods, a high molecular weight acrylic polymer crosslinked product (A) suitable for re-peeling can be prepared. It is preferable to use a charging method or the like.

In general, as a method for preparing an acrylic pressure-sensitive adhesive, there is a method of increasing a crosslinking fraction with a crosslinking agent after polymerizing in a solvent system to obtain an acrylic polymer with a low crosslinking fraction. It is difficult to balance the amount of functional monomers in the polymer and the cross-linking fraction, making it difficult to achieve both initial adhesion and appropriate release force after storage, and contaminating the adherend after release due to the formation of a low molecular weight. It is easy to do and is not preferable. Also, there is a method of preparing a pressure-sensitive adhesive by preparing a high molecular weight acrylic polymer by a UV polymerization method or the like, but this method is not preferable because the production cost increases. Emulsion polymerization is suitable as a method for synthesizing an acrylic polymer cross-linked product of a re-peeling adhesive because a high molecular weight adhesive can be easily obtained at a relatively low cost.

As the emulsifier, anionic emulsifiers and nonionic emulsifiers used in emulsion polymerization can be used without particular limitation. For example, anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether And nonionic emulsifiers. In both cases of anionic emulsifiers and nonionic emulsifiers, radical polymerization in which reactive functional groups such as propenyl groups, allyl groups and (meth) acryloyl groups are introduced into the emulsifiers in order to reduce adherence contamination. It is preferable to use a reactive reactive emulsifier. Radical polymerizable reactive emulsifiers are described, for example, in JP-A-4-53802.

Examples of the polymerization initiator include azo compounds such as 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (N, N′-dimethyleneisobutylamidine), potassium persulfate, A persulfate such as ammonium persulfate is used.

The water-dispersed pressure-sensitive adhesive composition of the present invention can be obtained by blending the acrylic polymer crosslinked product (A) and the crosslinking agent (B).

Examples of the crosslinking agent (B) include, as water-soluble crosslinking agents, epoxy crosslinking agents such as polyethylene glycol diglycidyl ether, water-dispersed isocyanate crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, and hydrophilized carbodiimides. Examples thereof include a system crosslinking agent, an active methylol crosslinking agent, an active alkoxymethyl crosslinking agent, and a metal chelate. Examples of the oil-soluble crosslinking agent include epoxy-based crosslinking agents such as N, N, N, N-tetraglycidyl m-xylenediamine, isocyanate-based crosslinking agents such as hexamethylene diisocyanate, and oil-soluble carbodiimide-based crosslinking agents. .

The cross-linking agent (B) is selected in such a way that the functional group of the cross-linking agent (B) is reactive with the functional group of the functional monomer (d) used in the preparation of the cross-linked product (A) by the acrylic polymer. Selected from those having no reactivity with the functional group of the functional monomer (c). For example, when a hydroxyl group-containing monomer such as 2-hydroxyethyl acrylate is used as the functional monomer (c) for securing initial adhesion, and a carboxyl group-containing monomer such as acrylic acid is used as the functional monomer (d) For this, an epoxy-based crosslinking agent is preferably used as the crosslinking agent (B).

The blending amount of the cross-linking agent (B) is not particularly limited, but it is preferable that the cross-linking fraction is 95% by weight or more after the acrylic polymer cross-linked product (A) is cross-linked with the cross-linking agent (B). . Usually, the functional group number (equivalent) of the crosslinking agent (B) is 1 to 1. with respect to the functional group number (equivalent) of the functional monomer (d) blended in the acrylic polymer crosslinked product (A) as a crosslinking component. It is preferable to blend so as to be about 5 times. When the number of functional groups (equivalent) of the cross-linking agent (B) is less than 1 time, the cross-linking reaction is insufficient, and the peeling force tends to increase. If it is more than 5 times, it will cause contamination by the remaining unreacted crosslinking agent, which is not preferable.

In addition, the water-dispersed pressure-sensitive adhesive composition of the present invention may contain various additives such as tackifiers, plasticizers, softeners, fillers, pigments, dyes, anti-aging agents, etc. as necessary. Can do.

In the pressure-sensitive adhesive tape of the present invention, a pressure-sensitive adhesive layer is formed on one side of a base material from a crosslinked product of the water-dispersed pressure-sensitive adhesive composition. The substrate is not particularly limited, and for example, a plastic film such as polyester or polypropylene, paper, a nonwoven fabric, a foam, a metal foil or the like can be used alone or a composite substrate thereof, and the substrate is subjected to surface treatment. Things can be used. A base material is about 9-120 micrometers normally.

The pressure-sensitive adhesive layer can be formed by directly applying the water-dispersed pressure-sensitive adhesive composition onto a substrate and drying it, and transferring the layer formed in the same manner on the separator onto the substrate. May be. The pressure-sensitive adhesive tape of the present invention is obtained as a sheet-like or tape-like form by providing a single layer or a plurality of pressure-sensitive adhesive layers on one or both sides of a substrate. The pressure-sensitive adhesive layer is usually about 1 to 50 μm.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In each example, “parts” means parts by weight.

Example 1
(Preparation of cross-linked acrylic polymer)
In a reactor equipped with a thermometer, stirrer, nitrogen inlet tube and reflux condenser, 60 parts of 2-ethylhexyl acrylate, 38 parts of methyl methacrylate, 1 part of acrylic acid, 1 part of 2-hydroxyethyl acrylate and an anionic reactive emulsifier A solution obtained by emulsifying 2.5 parts of Aqualon BC-2020 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with 144 parts of water was added, and the atmosphere was replaced with nitrogen for 2 hours. Subsequently, after raising the temperature to 55 ° C., 0.03 part of 2,2′-azobis (2-amidinopropane) hydrochloride was added and polymerization was performed for 8 hours. Then, it cooled to room temperature and neutralized with 10% ammonia water, and produced the acrylic polymer crosslinked material. The acrylic polymer crosslinked product had a Tg of −25 ° C. and a crosslinking fraction of 89 %.

(Preparation of water-dispersed PSA composition and production of PSA tape)
100 parts of the above acrylic polymer cross-linked product (solid content) is mixed with a water-soluble epoxy cross-linking agent (Denacol EX-614B, manufactured by Nagase Kasei Kogyo Co., Ltd.) with an epoxy group equivalent amount of acrylic acid in the acrylic polymer cross-linked product A water-dispersed pressure-sensitive adhesive composition was prepared by adding 2.4 parts so as to be equivalent to the carboxyl group. This water-dispersed pressure-sensitive adhesive composition was applied to a 12 μm polyethylene terephthalate base material and dried so that the thickness after drying was 5 μm, thereby preparing a pressure-sensitive adhesive tape. The crosslinking fraction after addition of the crosslinking agent was 96%.

Example 2
In Example 1, an acrylic polymer cross-linked product was prepared in the same manner as in Example 1 except that the amount of 2-ethylhexyl acrylate used was 55 parts and that 38 parts of methyl methacrylate was 43 parts of isobutyl methacrylate. The acrylic polymer crosslinked product had a Tg of −30 ° C. and a crosslinking fraction of 86%. Next, in the same manner as in Example 1, a water-dispersed pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive tape was prepared. The crosslinking fraction after addition of the crosslinking agent was 97%.

Comparative Example 1
In Example 1, an acrylic polymer cross-linked product was prepared in the same manner as in Example 1 except that the amount of 2-ethylhexyl acrylate used was 40 parts and that 38 parts of methyl methacrylate was 58 parts of methyl acrylate. The acrylic polymer crosslinked product had a Tg of −29 ° C. and a crosslinking fraction of 93%. Next, in the same manner as in Example 1, a water-dispersed pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive tape was prepared. The crosslinking fraction after addition of the crosslinking agent was 96%.

Comparative Example 2
In Example 1, an acrylic polymer cross-linked product was prepared in the same manner as in Example 1 except that the amount of 2-ethylhexyl acrylate used was 70 parts and the amount of methyl methacrylate used was 28 parts. The acrylic polymer crosslinked product had a Tg of −38 ° C. and a crosslinking fraction of 87%. Next, in the same manner as in Example 1, a water-dispersed pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive tape was prepared. The crosslinking fraction after addition of the crosslinking agent was 95%.

Comparative Example 3
In Example 1, the amount of acrylic acid 2-ethylhexyl used was 53 parts, the amount of methyl methacrylate used was 43 parts, and the amount of 2-hydroxyethyl acrylate used was 3 parts. A cross-linked polymer was prepared. The acrylic polymer crosslinked product had a Tg of -16 ° C and a crosslinking fraction of 93%. Next, in the same manner as in Example 1, a water-dispersed pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive tape was prepared. The crosslinking fraction after addition of the crosslinking agent was 96%.

Comparative Example 4
In Example 1, the amount of acrylic acid 2-ethylhexyl used was 60 parts, the amount of methyl methacrylate used was 36 parts, and the amount of 2-hydroxyethyl acrylate used was 3 parts. A cross-linked polymer was prepared. The acrylic polymer crosslinked product had a Tg of −26 ° C. and a crosslinking fraction of 92%. Next, in the same manner as in Example 1, a water-dispersed pressure-sensitive adhesive composition was prepared and a pressure-sensitive adhesive tape was prepared. The crosslinking fraction after addition of the crosslinking agent was 95%.

The following evaluation was performed about the adhesive tape obtained by the Example and the comparative example. The results are shown in Table 1.

(Initial adhesive strength)
A pressure-sensitive adhesive tape of 20 mm × 100 mm was pressure-bonded to the adherend by a method of reciprocating once with a 2 kg roller, and the force required for the peeling was measured to evaluate initial adhesion (180 degree peeling, pulling speed 30 m / min, 23 ° C. , 65% RH). Substrate: Stainless steel plate (SUS430BA). Standing condition: 23 ° C. × 20 minutes.

(Aging force over time)
The sample pressure-bonded to the adherend by the same method as above was heated at 60 ° C. for 7 days, and then allowed to cool to room temperature.

As is clear from the results in Table 1, each of the pressure-sensitive adhesive tapes of Examples 1 and 2 of the present invention has an initial adhesiveness and an appropriate peeling force over time as compared with the pressure-sensitive adhesive tapes of Comparative Examples 1 to 4. You can see that In Table 1, 2EHA: 2-ethylhexyl acrylate, MMA: methyl methacrylate, iBMA: isobutyl methacrylate, MA: methyl acrylate, AA: 1 part of acrylic acid, HEA: 2-hydroxyethyl acrylate.

Claims (4)

A water-dispersed pressure-sensitive adhesive composition comprising an acrylic polymer crosslinked product (A) obtained by emulsion polymerization having a crosslinking fraction of 85% by weight or more and a crosslinking agent (B),
The crosslinking agent (B) is at least one selected from the group consisting of an epoxy crosslinking agent, an oxazoline crosslinking agent, and an aziridine crosslinking agent,
The crosslinking fraction is calculated according to the following general formula:
The pressure-sensitive adhesive composition contains an emulsifier,
The acrylic polymer cross-linked product (A) is an acrylic acid alkyl ester (a) having 4 to 12 carbon atoms in the alkyl group (a) of 50% by weight or more, and a methacrylic acid alkyl ester (b) 30 having 1 to 4 carbon atoms in the alkyl group. It is obtained by emulsion polymerization of a monomer blend containing ˜45% by weight, hydroxyl group-containing monomer (c) 0.5 to 2.5% by weight and carboxyl group-containing monomer (d) with the emulsifier. A water-dispersed pressure-sensitive adhesive composition characterized by the above.
Wherein the crosslinking fraction means the ratio of the cross-linking moiety in the acrylic polymer crosslinked product (A), dried acrylic polymer crosslinked product (A) the diameter 0.2μm Teflon wrapped with (R) film, acetate The dissolved portion is extracted in ethyl at room temperature for 1 week, and the acrylic polymer crosslinked product (A) remaining in the Teflon film is taken out and calculated by the following formula.
Cross-linked fraction (% by weight) = ( cross-linked acrylic polymer (A) (g) remaining in the Teflon film ) / dried cross-linked acrylic polymer (A) (g)) × 100. The water-dispersed pressure-sensitive adhesive composition according to claim 1, wherein the monomer composition is adjusted so that the glass transition temperature of the resulting acrylic polymer crosslinked product (A) is -20 to -35 ° C. . 3. The water-dispersed pressure-sensitive adhesive according to claim 1, wherein the acrylic polymer cross-linked product (A) is cross-linked with a cross-linking agent (B) so that the cross-linking fraction is 95% by weight or more. Composition. The adhesive tape in which the adhesive layer is formed on the base material with the crosslinked material of the water dispersion-type adhesive composition as described in any one of Claims 1-3.