JPS5949265B2 - Water-dispersed pressure-sensitive adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an acrylic water-dispersed pressure sensitive adhesive composition.

In recent years, acrylic pressure-sensitive adhesives have become widely used in place of conventional natural rubber-based and synthetic rubber-based pressure-sensitive adhesives due to their excellent adhesive properties and durability.

Among these types of adhesives, water-dispersible adhesives that do not use organic solvents have recently been researched and developed from the viewpoint of resource saving and environmental hygiene. Such acrylic water-dispersed pressure-sensitive adhesives are generally made by adding acrylic unsaturated monomers such as acrylic esters and methacrylic esters to modifying monomers such as acrylic acid, styrene, and vinyl acetate as necessary. It is produced by emulsion polymerization in an aqueous medium.

The acrylic polymer obtained by this method, which is sticky at room temperature, has a solution weight of 1. It is known that it has a relatively large molecular weight compared to polymers made by polymers, and therefore can provide high cohesive strength as a pressure-sensitive adhesive. However, despite these advantages, it is not applied to applications that require high adhesive strength and high cohesive strength, such as applications in which metal plates, plastic plates, etc. are bonded in a bent state to an adherend having a curved surface. In some cases, it did not necessarily show satisfactory cohesion. In other words, in applications such as the above example, a restoring force acts on the bent metal plate or plastic plate, so the so-called repulsion resistant material has a high adhesive strength and cohesive force that can withstand this restoring force. Although excellent repulsion resistance is required, it has not been possible to satisfy this requirement. In addition, when the bonded area is exposed to relatively high temperatures in applications such as this,
The cohesive force was significantly reduced and it could hardly be used.

Therefore, in order to further increase the cohesive strength of this type of adhesive, internal crosslinking agents such as dimethacrylate and divinylbenzene are used when emulsion polymerizing acrylic unsaturated monomers, and polymer dispersion after emulsion polymerization is used. The liquid contains a crosslinking agent similar to that in organic solvent type, such as a melamine compound,
Attempts have been made to incorporate epoxy compounds, metal salts, etc.

However, with such methods, the crosslinking is generally non-uniform and the cohesive force is not so large compared to the degree of crosslinking.
Moreover, a decrease in adhesive strength was observed with the improvement in cohesive strength, and as a result, it was not possible to easily obtain a pressure-sensitive adhesive having high adhesive strength, high cohesive strength, and excellent repulsion resistance. In addition, it is difficult to select the type and amount of crosslinking agent to be used, and there are also problems in terms of productivity, such as the need for thermal energy for crosslinking which cannot be ignored in some cases. In light of these circumstances, the inventors have developed a system that can provide high adhesive strength and high cohesive strength without using a crosslinking agent, and has repulsion resistance that does not show any decrease in cohesive strength even at relatively high temperatures. We have been conducting intensive research to develop an excellent water-dispersible acrylic pressure-sensitive adhesive.

In the course of this research, prior to emulsion polymerization of acrylic unsaturated monomers, a polymer dispersion was prepared by emulsion polymerizing a specific ethylenically unsaturated monomer, and then acrylic unsaturated monomers were added to this polymer dispersion. It was discovered that when emulsion polymerization is carried out with the addition of 100% acetic acid, very good results can be obtained in terms of both adhesive strength and cohesive strength, and this invention has been completed. That is, the present invention provides that a homopolymer or copolymer exhibits tackiness at room temperature and has a glass transition point of 2,730 K or higher is added to an aqueous dispersion of a modifying polymer prepared by emulsion polymerization of an ethylenically unsaturated monomer and has a glass transition point of 2,730 K or higher. The present invention relates to a water-dispersible pressure-sensitive adhesive composition obtained by adding an acrylic unsaturated monomer that can have a temperature of 2500 K or less and carrying out emulsion polymerization.

By the way, in fields other than adhesives, a technique for modifying the properties of the above-mentioned polymer by adding other unsaturated monomers to a polymer dispersion and carrying out emulsion polymerization has already been known. For example, in the synthesis of ABS resin as an impact-resistant resin, in the production of polymer films with excellent transparency and weather resistance, and in the production of processing aids for polyvinyl chloride, polymethyl methacrylate is used with styrene and acrylic ester. There are examples of its use in reforming methods. However, the technique of preparing a polymer dispersion liquid different from the polymer to be modified, adding thereto an unsaturated monomer to form the polymer to be modified, and carrying out emulsion polymerization as in the present invention is not well known. However, if technology related to pressure-sensitive adhesives, especially acrylic pressure-sensitive adhesives, is used, and in this case, any polymer dispersion is prepared and any acrylic unsaturated monomer is emulsion polymerized, There are no research reports regarding whether good results can be obtained in terms of both adhesive strength and cohesive strength.

In this way, in this invention, by emulsion polymerizing the specific acrylic unsaturated monomer in a dispersion of a specific modifying polymer, a crosslinking agent that does not require any conventional crosslinking agent can be obtained. Alternatively, the cohesive force can be greatly improved with a very small amount of use, and in this case, good adhesive strength comparable to that obtained by simply emulsion polymerizing an atarylic unsaturated monomer can be obtained. In the end, they succeeded for the first time in obtaining a pressure-sensitive adhesive with high adhesive strength and high cohesive strength, and extremely high repulsion resistance, with no significant decrease in cohesive strength at relatively high temperatures. It is something.

The reason why the above-mentioned effects are obtained in this invention is not necessarily clear. However, simply blending the dispersion of the specific modifying polymer used in this invention with the dispersion of the adhesive acrylic polymer does not improve the cohesive force, mainly at high temperatures. Adhesive strength also tends to be low, making it impossible to obtain an adhesive with excellent repulsion resistance. Furthermore, in this invention, the specific ethylenically unsaturated monomer used to form the modifying polymer is emulsion polymerized together with the acrylic unsaturated monomer, and the adhesive strength and tackiness at around room temperature are Either force or cohesion is severely impaired. Based on these facts, in this invention, when an acrylic unsaturated monomer is added to an aqueous dispersion of the specific modifying polymer and emulsion polymerization is carried out, the acrylic polymer formed by polymerization is the above-mentioned modifying polymer. In other words, the two polymers are not simply dispersed and mixed in the form of particles, but polymer particles are produced in which the modifying polymer is the core and the acrylic polymer has a two-layer structure. It is clear that this greatly contributes to the significant improvement in cohesive force and the maintenance of adhesive strength and adhesion, thereby significantly improving repulsion resistance.

In this invention, first, the ethylenically unsaturated monomer is emulsion polymerized according to a conventional method, so that the glass transition point is 2.
An aqueous dispersion of a modifying polymer having a strength of 73 K or more, preferably 30 K or more is prepared.

Here, if the glass transition point of the polymer is lower than 273 K, the cohesive force of the final pressure-sensitive adhesive cannot be sufficiently improved. The average molecular weight of the modifying polymer is not particularly limited, but it is generally 100,000 or more, preferably 300,000 or more. As the above-mentioned ethylenically unsaturated monomer, one or more kinds of which the homopolymer or copolymer thereof can exhibit the above-mentioned predetermined glass transition point is used, but the glass transition point of the copolymer is 2 or more.
Among the two or more monomers that can have a K of 73 or more,
The glass transition point of the homopolymer of each monomer is 27.
In addition to monomer mixtures that can have a K of 3 or higher, unsaturated monomers that can have a homopolymer with a glass transition point of 273 or higher and unsaturated monomers that can have a homopolymer with a glass transition point of lower than 27tK. Also includes mixtures of.

The latter monomer mixture may be one that can exhibit a glass transition point of 27'f'K or higher when formed into a copolymer depending on its composition ratio. The inventors have developed an unsaturated monomer selected from the group of styrene, vinyl acetate, acrylonitrile, and methacrylonitrile as such an ethylenically unsaturated monomer whose homopolymer can have a glass transition point of 3000 K or more. or a homopolymer selected from the group of acrylic esters, methacrylic esters or styrene derivatives has a glass transition point of 273:
It has been found that unsaturated monomers that can have K or higher (hereinafter, unsaturated monomers belonging to both groups are referred to as component A monomers) are particularly suitable. Specific examples of unsaturated monomers belonging to the latter group include cyclohexyl acrylate (289 K), methyl acrylate (279 K), butyl methacrylate (293 K), N-N dimethylaminoethyl methacrylate ( 289 raw K), hexadecyl methacrylate (2882K), 2-methoxyethyl methacrylate (
2862K), 4-butylstyrene (2790K), unsaturated monomers whose homopolymer glass transition point can be 2730K or higher, and 2-butyl methacrylate (3
18WK), 3,3-dimethylbutyl methacrylate (
318, K), 3,3-dimethyl-2-butyl methacrylate (3813K), ethyl methacrylate (338K), glycidyl methacrylate (3193K), isobornyl methacrylate (3831K), isobutyl methacrylate (326(K) , isopropyl methacrylate (354 (K), methyl methacrylate (378), phenyl methacrylate (378 (K)), n-propyl methacrylate (3087K), isobornyl acrylate (3
673K), 4-Tert-butylstyrene (4033
K), 2,4-diisopropylstyrene (4413K)
, 2,5-dimethylstyrene (4164K), 3,4-
Diethylstyrene (3824K), 2-hydroxymethylstyrene (4334K), 4-methylstyrene (36
There are unsaturated monomers whose homopolymers can have glass transition points of 3000K or higher, such as 2-methylstyrene (366K) and 2-methylstyrene (366K).

Among these unsaturated monomers belonging to the latter group, those whose homopolymer glass transition point can be 3000 K or higher are desirable, and among these, methyl methacrylate is the most preferred.

In this invention, it is preferable to use one or more of these A-component monomers, appropriately selected from one or both of the two groups, but it is also possible to copolymerize with these A-component monomers. An unsaturated monomer (hereinafter referred to as a component B monomer) which can make the copolymer have a glass transition point of 273 K or higher may be used in combination.

Such B component monomers include unsaturated monomers such as acrylic acid, methacrylic acid, and itaconic acid whose homopolymers can have a glass transition temperature of 273 K or higher, butyl acrylate, ethyl acrylate, and acrylic acid. The glass transition point of its homopolymers such as 2-ethylhexyl acid is 27
One or more monomers used in general acrylic pressure-sensitive adhesives, such as unsaturated monomers having a K lower than 3, are used.

The amount of these component B monomers to be used is one of the factors that determines the glass transition point of the copolymer, so it may be determined appropriately depending on the types of both component A and B monomers, taking this point into consideration. However, if the amount used is too large, it may interfere with the remarkable cohesive force improvement effect achieved by using the component A monomer, so it is preferably 50% by weight or less based on the total monomer, preferably 30% by weight or less based on the total monomer.
It should be less than % by weight. The aqueous dispersion of the modifying polymer thus prepared is then subjected to a second emulsion polymerization by adding an acrylic unsaturated monomer thereto.
In this case, it is desirable that the surface tension of the dispersion liquid be set to an appropriate value.

In other words, according to the findings of the inventors, if the surface tension of the dispersion is too low, the acrylic unsaturated monomer will not effectively diffuse into the polymer particles of the dispersion, resulting in secondary emulsification. During polymerization, polymer particles consisting solely of homopolymers or copolymers of the above acrylic monomers are mainly produced, and the proportion of acrylic polymer particles with the modifying polymer as the core, that is, polymer particles with a two-layer structure, is produced. It was found that the adhesive strength could not be improved sufficiently. The generally recommended surface tension of the dispersion liquid is usually 43 dyne/CwL or more, particularly preferably 55 dyne/CwL. That's all. The surface tension of such a dispersion mainly depends on the type and amount of the emulsifier used when emulsion polymerizing the ethylenically unsaturated monomer. Therefore, if the surface tension of the dispersion after emulsion polymerization is too low, the surface tension may be increased by dialyzing the dispersion or adding an acid, alkali, or salt before adding the acrylic unsaturated monomer. It is better. As the acids, alkalis, and salts mentioned above, monovalent inorganic salts or organic salts such as hydrochloric acid, sodium chloride, sodium sulfate, and sodium acetate are suitable, and in small amounts, divalent metal salts such as calcium chloride are also suitable. Can be used. In this invention, the acrylic unsaturated monomer to be added to the aqueous dispersion of the modifying polymer is one or a monomer whose homopolymer or copolymer exhibits tackiness at room temperature and whose glass transition temperature is 250 K or less. Two or more types are used.

However, if the homopolymer or copolymer does not exhibit tackiness at room temperature, or if the monomer has a glass transition point exceeding 250°C, problems may arise in the tackiness or adhesion of the resulting pressure-sensitive adhesive. It arises. A typical example of such an acrylic unsaturated monomer is an alkyl ester of acrylic acid or methacrylic acid and an alcohol having 12 or less carbon atoms as the main monomer, and the above main monomers may be used as necessary. Examples include those containing 50% by weight or less of other copolymerizable monomers. Particularly suitable copolymerizable monomers include acrylic acid, methacrylic acid, maleic acid, vinyl acetate, vinyl propionate, and esters of acrylic acid or methacrylic acid other than the above-mentioned main monomers. The above esters include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, N-N-dimethylaminoethyl acrylate, N-N dimethylaminoethyl methacrylate, N-tert-butylaminoethyl Includes acrylate, glycidyl acrylate, etc.

In addition, mono- or diesters of vinyl chloride, crotonic acid, itaconic acid, and maleic acid, bis(N-N-dimethylaminoethyl) maleate, acrylamide, methacrylamide, N-methylolacrylamide, and the like can be used. Furthermore, it is also possible to use conventionally known internal crosslinking monomers such as dimethacrylate, diacrylate, and divinylbenzene, thereby further improving the cohesive force of the resulting pressure-sensitive adhesive. can. The amount of the above-mentioned acrylic unsaturated monomer added is generally 50 to 4,000 parts by weight per 100 parts by weight of the modifying polymer.
The amount is preferably 100 to 3,000 parts by weight.

If this amount is too large, the cohesive force cannot be sufficiently improved, and if the amount is too small, even if the cohesive force can be improved, the adhesive force will decrease. No cohesive pressure sensitive adhesive is obtained. Of course, the optimum amount to be added varies depending on the composition of the modifying polymer, the surface tension and salt concentration of the dispersion, the composition of the acrylic unsaturated monomer, etc., so it should be set appropriately with these things in mind. It is better to do so. In this invention, such emulsion polymerization of an acrylic unsaturated monomer is carried out by uniformly dispersing and mixing the above monomer in a dispersion of a modifying polymer, and then preparing a dispersion of a modifying polymer. The same known polymerization initiator as used in the actual polymerization is added and the polymerization is carried out at room temperature or under heating.

Typical polymerization initiators are ammonium persulfate,
Redox catalysts include persulfates such as potassium persulfate, hydrogen peroxide, and combinations of these with sodium bisulfite, sodium ascorbate, metal salts, amines, and the like. Other organic peroxides such as benzyl peroxide can also be used. The amount of the polymerization initiator used is generally 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of the atarylic unsaturated monomer. If the polymerization initiator used is water-soluble, it can be added to the dispersion as an aqueous solution, but if it is a poorly water-soluble one such as benzoyl peroxide, it can be dissolved in an organic solvent such as toluene or benzene or added to the dispersion. It is dissolved in the acrylic unsaturated monomer and added to the dispersion. In the latter case, it is preferable to stir and disperse the initiator solution uniformly in the dispersion before starting the polymerization. The aqueous dispersion obtained by emulsion polymerization of the acrylic unsaturated monomer in this manner contains an acrylic polymer with an average molecular weight of 300,000 or more that has grown from the modifying polymer as a core, and is directly sensitized. When applied as a pressure adhesive, it exhibits high adhesive strength and cohesive strength, and also exhibits pressure-sensitive adhesive properties with excellent rebound resistance and no decrease in cohesive strength at relatively high temperatures.

As described above, the present invention includes polymer particles having a two-layer structure of a modifying polymer and an acrylic polymer, which are obtained by adding an acrylic unsaturated monomer to an aqueous dispersion of a modifying polymer and carrying out emulsion polymerization. Although the aqueous dispersion can be used as a pressure-sensitive adhesive as it is, various additives such as those described below may be added in order to further improve the adhesive properties of this pressure-sensitive adhesive.

First, if it is desired to increase the adhesive strength of the adhesive, add up to 50 parts by weight, preferably 5 parts by weight, of a tackifying resin having a softening point of 330 K or higher based on 100 parts by weight of the polymer component in the dispersion. It can be blended in a range of 40 parts by weight.

Using a tackifier resin with a softening point lower than 3300K,
If the blending ratio is too large, the cohesive force of the adhesive may be impaired, and heat resistance and cold resistance are also adversely affected, which is not preferable. Examples of such adhesion-imparting resins include Ester Gum H (softening point 3450K) and Bencel A (softening point 375:'K) manufactured by Arakawa Chemical Industries, Ltd.
, Dimarex resin manufactured by Hercules (softening point 4)
18) K), rosin-based adhesive resins such as Pentaline C (softening point 405 K), Hiretsu C-110X manufactured by Mitsui Petrochemicals (softening point 373 K), Pico Pale 110SF manufactured by Pico (softening point 3800K), petroleum resin-based tackifier resin such as Picodiene 2215 (softening point 373K) manufactured by Hercules, coumaron indene resin-based tackifier resin such as Kobe Yuka Co., Ltd.'s Coumaron resin (softening point 38g'K). Resin, YS Polyster (softening point 3) manufactured by Yasushi Oil Co.
7fK), an oil-soluble phenolic adhesive resin,
and xylene resin-based adhesion imparting resins.

When blending the adhesion-imparting resin, either fine resin powder is added to water containing a dispersion liquid in advance to form a slurry, or an emulsifier and water are added to an organic solvent solution to form a resin emulsion. It is better to mix it. Examples of the organic solvent used for the latter include benzene, toluene, hexane, and methyl ethyl ketone, and as the emulsifier, any known nonionic or anionic emulsifier can be used, but it is preferable to use the It is preferable to use the same or similar emulsifier to that used.
On the other hand, in order to improve the initial adhesive strength (tack) of the adhesive, softeners such as liquid tackifier resins and plasticizers used in general pressure-sensitive adhesives may be added.

The blending ratio is preferably up to 50 parts by weight per 100 parts by weight of the polymer component in the dispersion; if the amount is too large, properties such as cohesive force and heat resistance will be impaired. These softeners can be mixed directly into the dispersion, or
Alternatively, if there is a risk of agglomeration in the liquid if blended as is, it may be blended as a slurry or resin emulsion similar to the case of the solid adhesion-imparting resin. Also, it is liquid at room temperature and has an average molecular weight of 8,000 to 200,00.
0 low molecular weight polymers may also be included to improve initial adhesion (tack).

As such a low molecular weight polymer, an acrylic low molecular weight polymer having the same composition as the acrylic unsaturated monomer used in the second emulsion polymerization is preferred from the viewpoint of compatibility. The amount to be blended varies depending on the composition, but it is generally recommended that the amount be up to 200 parts by weight per 100 parts by weight of the polymer component in the dispersion; too much is not preferable because properties such as cohesive force and heat resistance will be impaired. . Further, if it is desired to further increase the cohesive force of such an adhesive, an appropriate crosslinking agent may be added.

It is sufficient that the blending ratio is usually up to 2 parts by weight, preferably within the range of 0.005 to 1 part by weight, based on 100 parts by weight of the polymer component in the dispersion. When blending, it can be blended as an aqueous solution or emulsion, or as an organic solvent solution.
Specific examples of crosslinking agents include triglycidyl isocyanurate, aliphatic glycidyl ester type, alicyclic glycidyl ether type, bisphenol type, aliphatic type, etc.
- There are epoxy compounds such as low molecular weight epoxy compounds having a 2-epoxy group, and commercially available products include Epicote #828 and Epicote #1031 manufactured by Ciba Geigi, Kohon #834 manufactured by Ciel Corporation, and ECN #1235 manufactured by Ciba Corporation. , TEPIC manufactured by Nissan Chemical Co., Ltd., etc.

Also, melamine or its derivatives such as polymethylol melamine such as mono-, di-, tri-, tetra-, penta- or hexamethylol melamine, melamine compounds such as trimethoxymethyl melamine, tributoxymethyl melamine, and commercially available Takiel # manufactured by Sumitomo Chemical Co., Ltd. Examples include reactive phenolic resins such as No. 201, polyvalent metal chelate compounds such as titanium acetylacetonate and ammonium titanium lactate, and various other isocyanate compounds and metal salts. The water-dispersed pressure-sensitive adhesive composition of the present invention may further contain known compounding agents such as colorants, fillers, and anti-aging agents, if necessary.

The adhesive composition of the present invention thus obtained has high adhesive strength and cohesive strength, shows no decrease in cohesive strength even at relatively high temperatures, and has excellent repulsion resistance and other properties. Furthermore, it exhibits good adhesion and rebound resistance even to difficult-to-adhesive adherends such as polyethylene and polypropylene.
Furthermore, it exhibits excellent initial adhesive strength (tackiness). Therefore, it can be applied to various applications that take advantage of these characteristics, and can also be effectively used as general pressure-sensitive adhesive tapes and sheets. Examples of the invention will be described.

In the following, parts mean parts by weight, and adhesive strength, holding power (cohesive force), and repulsion resistance were measured by the following methods. Adhesive strength> A pressure-sensitive adhesive composition was coated on both sides of a 25μ polyester film to a thickness of 50μ on one side and dried at 100°C for 3 minutes to make a double-sided adhesive tape.
The 1800 peel adhesion strength (9/20 scale) was measured using the following method.

<Holding power> A double-sided adhesive tape similar to the adhesive strength test was made, and this was
Pasted on 25 x 25 mm pieces of Bakelite board, 40
The time (minutes) until the Bakelite plate falls was measured under a load of 1 kg at 80°C and 80°C.

Repulsion resistance> 50% of the pressure sensitive adhesive composition was applied to a 0.3 mm aluminum plate.
Coat to a thickness of μ and dry at 100°C for 3 minutes to make a test piece.
After bending and pasting it on an aluminum cylinder with a diameter of m,
When the test piece was stored at 0°C for 24 hours, the distance (MO) that the test piece rose from the cylinder was measured.

Example 1 A mixture consisting of 100 parts of styrene, 2 parts of sodium lauryl sulfate, 0.3 parts of potassium persulfate, and 100 parts of ion-exchanged water was reacted at 70°C under a nitrogen stream for 6 hours to achieve a glass transition point of 373°C. An aqueous dispersion (emulsion) of a polymer for modification was prepared.

The solid content of this dispersion was 49% by weight, and the surface tension of the dispersion was 57 dyn using a CBVP surface tension meter (manufactured by Kyowa Kagakusha).
e/CT! It was L. Next, a monomer mixture consisting of 350 parts of water, 65 parts of 2-ethylhexyl acrylate, 30 parts of ethyl acrylate, and 5 parts of acrylic acid (glass transition point 238 After stirring and mixing for about 30 minutes, an aqueous polymerization initiator solution prepared by dissolving 1 part of potassium persulfate in 50 parts of water was added, and the mixture was allowed to react at 70°C under a nitrogen stream for 5 hours. Thus, a water-dispersible pressure-sensitive adhesive composition of the present invention was obtained. Comparative Example 1 Acrylinoleic acid 2-ethynolehexynole 65 sounds - 30 parts of ethyl acrylate, 5 parts of acrylic acid, 2 parts of sodium lauryl sulfate, 0.3 parts of potassium persulfate, and 10 parts of ion-exchanged water
A mixture consisting of 0 parts was reacted at 70°C for 6 hours under a nitrogen stream to form a mixture that was sticky at room temperature and had a glass transition point of 238.
, prepare an aqueous dispersion consisting of an acrylic polymer of K,
This was used as a water-dispersed pressure-sensitive adhesive composition.

This composition corresponds to Example 1 in which the primary emulsion polymerization was not performed. Comparative Example 2 A mixture consisting of 65 parts of 2-ethylhexyl acrylate, 30 parts of ethyl acrylate, 5 parts of acrylic acid, 25 parts of styrene, 2 parts of sodium lauryl sulfate, 0.3 parts of potassium persulfate, and 125 parts of ion-exchanged water, 70 under nitrogen flow
A water-dispersed pressure-sensitive adhesive composition was obtained by reacting at ℃ for 6 hours.

In this composition, all of the unsaturated monomers used in Example 1 were simultaneously emulsion polymerized. The glass transition temperature of the polymer in the composition was 263K. Comparative Example 3 25 parts of the aqueous dispersion of the modifying polymer (polystyrene) prepared in the first emulsion polymerization of Example 1 was blended with 100 parts of the aqueous dispersion of the acrylic polymer prepared in Comparative Example 1. A water-dispersed pressure-sensitive adhesive composition was prepared.

Comparative Example 4 100 parts of ethyl acrylate, 2 parts of sodium lauryl sulfate
Oton L potassium persulfate 0.3 parts and ion exchange water 100 parts
A mixture consisting of 50% and 50% was reacted at 70° C. for 6 hours under a nitrogen stream to prepare an aqueous dispersion of a polymer having a glass transition point of 249°K.

The same acrylic monomer mixture as in Example 1 was added to this aqueous dispersion and emulsion polymerization was performed to obtain a water-dispersed pressure-sensitive adhesive composition. The adhesive strength, cohesive force, and repulsion resistance of each of the pressure-sensitive adhesives of Example 1 and Comparative Examples 1 to 4 were investigated, and the results were as shown in Table 1 below.

Example 2 30 parts of methyl methacrylate, 70 parts of vinyl acetate
By reacting a mixture consisting of 1 part, Neugen EAl6O (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 3 parts of ammonium persulfate, and 100 parts of ion-exchanged water for 6 hours at 70°C under a nitrogen stream, the glass transition point was 316. An aqueous dispersion of an anti-K modifying polymer was prepared.

The solid content of this dispersion was 49% by weight, and the surface tension of the dispersion was 55 dyne/CrrL. Next, a monomer mixture consisting of 95 parts of isooctyl acrylate, 2 parts of maleic acid and 3 parts of methacrylic acid was added to the above dispersion (
Copolymer glass transition point 2300K) 200 parts and water 1
Add 80 copies! After stirring for 30 minutes, a polymerization initiator solution prepared by dissolving 0.5 parts of ammonium persulfate in 20 parts of water was added, and the mixture was reacted for 5 hours at 70°C under a nitrogen stream.
A water-dispersed pressure-sensitive adhesive composition of this invention was obtained. Example
A mixture consisting of 70 parts of 3-styrene, 30 parts of ethyl acrylate, 1 part of sodium lauryl sulfate, 1 part of Neugen EAl7O (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 0.5 parts of potassium persulfate, and 100 parts of ion-exchanged water was heated in a nitrogen stream. 6 at below 70℃
By reacting for a period of time, an aqueous dispersion of a modifying polymer having a glass transition point of 3340K was prepared.

The solid content of this dispersion was 49% by weight, and the surface tension of the dispersion was 56 dyne/CIrL. Next, 85 parts of n-butyl acrylate and 10 parts of vinyl acetate were added to the above dispersion.
600 parts of a monomer mixture (glass transition point of the copolymer: 230 monomer K) consisting of 1 part and 5 parts of acrylic acid and 500 parts of water were added, and after stirring for 30 minutes, 1 part of potassium persulfate was dissolved in 100 parts of water. An aqueous polymerization initiator solution was added thereto, and the mixture was reacted at 70° C. for 6 hours under a nitrogen stream to obtain a water-dispersed pressure-sensitive adhesive composition of the present invention. Example 4 In addition to the adhesive composition according to Example 1, Pentaline C- manufactured by Hercules was added to 100 parts of the polymer of this composition.
50 (previous adhesion imparting resin; 50% by weight aqueous dispersion) 20
The water-dispersed pressure-sensitive adhesive composition of the present invention was prepared by blending the following parts.

Example 5 In addition to the adhesive composition according to Example 1, 0.05 part of TEPIC (the above-mentioned crosslinking agent) manufactured by Nissan Chemical Co., Ltd. was dissolved in 1 part of water based on 100 parts of the polymer of this composition. A water-dispersed pressure-sensitive adhesive composition of the present invention was prepared by blending an aqueous crosslinking agent solution.

Example 6 A mixture consisting of 65 parts of 2-ethylhexyl acrylate, 30 parts of ethyl acrylate, 5 parts of acrylic acid, 1 part of lauryl mercaptan, 0.1 part of 2,2'-azobisisobutyronitrile, and 20 parts of toluene was prepared. , reacted at 60°C for 10 hours and is liquid at room temperature.The average molecular weight is 60,000.
created a low molecular weight polymer.

Polymer 1 of this composition was added to the adhesive composition according to Example 1.
00 parts, and 60 parts of the above-mentioned low molecular weight polymer were blended to prepare a water-dispersed pressure-sensitive adhesive composition of the present invention.

The results of examining the adhesive force, cohesive force, and rebound resistance of each of the pressure-sensitive adhesive compositions of Examples 2 to 6 above were as shown in Table 2 below.

Claims (1)

[Claims] 1. A homopolymer or copolymer that exhibits tackiness at room temperature is added to an aqueous dispersion of a modifying polymer having a glass transition point of 273°K or higher prepared by emulsion polymerization of an ethylenically unsaturated monomer. A water-dispersed pressure-sensitive adhesive composition obtained by emulsion polymerization with the addition of an acrylic unsaturated monomer capable of exhibiting the same properties as above and having a glass transition point of 250°K or less. 2 The ethylenically unsaturated monomer is styrene, vinyl acetate,
Selected from at least one of the group of acrylonitrile and methacrylonitrile, and the group of acrylic esters, methacrylic esters, and styrene derivatives whose homopolymers can have a glass transition point of 273°K or higher. A water-dispersed pressure-sensitive adhesive composition according to claim 1. 3 The ethylenically unsaturated monomer is styrene, vinyl acetate,
An unsaturated monomer selected from at least one of the group of acrylonitrile and methacrylonitrile, and the group of acrylic esters, methacrylic esters, and styrene derivatives whose homopolymers can have a glass transition temperature of 273°K or higher. and another unsaturated monomer which can be copolymerized with this monomer and whose copolymer has a glass transition temperature of 273°K or higher, and the latter monomer accounts for 50% by weight of the total monomers. % or less. % or less. 4. The unsaturated monomer selected from the group of acrylic esters, methacrylic esters and styrene derivatives is one whose homopolymer can exhibit a glass transition point of 300°K or higher. The water-dispersed pressure-sensitive adhesive composition described in 1. 5. The water-dispersed pressure-sensitive adhesive composition according to claim 4, wherein the methacrylic acid ester is methyl methacrylate. 6 The surface tension of the aqueous dispersion of the modifying polymer is 43 dyn.
The water-dispersed pressure-sensitive adhesive composition according to any one of claims 1 to 5, which has a particle diameter of e/cm or more. 7 The acrylic unsaturated monomer is an alkyl ester of acrylic acid or methacrylic acid and an alcohol having 12 or less carbon atoms as the main monomer, and if necessary, other monomers copolymerizable with the above main monomer are used. 7. The water-dispersed pressure-sensitive adhesive composition according to claim 1, which contains 50% by weight or less of the water-dispersed pressure-sensitive adhesive composition. 8 Other monomers copolymerizable with the main monomer are selected from esters of acrylic acid or methacrylic acid, acrylic acid, methacrylic acid, maleic acid, vinyl acetate, and vinyl propionate. The water-dispersed pressure-sensitive adhesive composition according to claim 7. 9. The water-dispersed pressure sensitive product according to any one of claims 1 to 8, wherein 50 to 4,000 parts by weight of the acrylic unsaturated monomer is used per 100 parts by weight of the modifying polymer. Adhesive composition. 10 Claim 1 comprising blending up to 50 parts by weight of a tackifying resin with a softening point of 330°K or higher with respect to 100 parts by weight of the polymer component after emulsion polymerization of an acrylic unsaturated monomer. The water-dispersed pressure-sensitive adhesive composition according to any one of items 1 to 9. 11. According to any one of claims 1 to 10, wherein up to 50 parts by weight of a softener is blended with 100 parts by weight of the polymer component after emulsion polymerization of the acrylic unsaturated monomer. water-dispersed pressure-sensitive adhesive composition.