JPS6343437B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-dispersed pressure-sensitive adhesive composition that has excellent cohesive force, adhesive strength, and repulsion resistance. Currently, pressure-sensitive adhesives include natural rubber-based, synthetic rubber-based, and acrylic-based adhesives, and are used in the form of tapes, sheets, etc. for many purposes. Among these, acrylic pressure-sensitive adhesives have become widely popular in recent years due to their excellent adhesiveness and durability. Acrylic pressure-sensitive adhesives include organic solvent solution type and water dispersion type, but water dispersion type is preferred from the viewpoint of environmental hygiene and resource saving. The main component of acrylic pressure-sensitive adhesives is an acrylic ester polymer that is sticky at room temperature.
Such a polymer alone has insufficient cohesive strength and can only be used as a pressure-sensitive adhesive unsatisfactory.
For this reason, unsaturated monomers such as unsaturated carboxylic acids, vinyl acetate, styrene, acrylonitrile, methacrylic acid esters, etc., which do not have particular tackiness at room temperature but have high cohesive strength, or which have tackiness at room temperature. It has been carried out to copolymerize acrylic esters other than the acrylic esters that yield polymers with acrylic esters that yield polymers that are sticky at room temperature. When obtaining a water-dispersed acrylic pressure-sensitive adhesive, such copolymerization is usually carried out by emulsion polymerization, which makes it possible to obtain a polymer with a higher molecular weight than by solution polymerization using an organic solvent. Therefore, it is known that pressure-sensitive adhesives having high cohesive strength can be obtained. However, pressure-sensitive adhesive tapes or sheets obtained using the acrylic water-dispersed pressure-sensitive adhesive obtained in this way can be used on curved surfaces of adherends.
For example, if the tape or sheet is bent and adhered to a curved surface such as a cylindrical container made of plastic, glass, ceramics, or metal, the tape or sheet often peels off from its edges due to repulsive force. Can be seen. This phenomenon becomes extremely noticeable at relatively high temperatures and is hardly of practical use.
This phenomenon is caused by the fact that the pressure-sensitive adhesive still lacks cohesive strength and adhesive strength. Therefore, in order to obtain the ability to adhere a tape or sheet to a curved surface while resisting the above-mentioned repulsive force, that is, to obtain so-called repulsion resistance, pressure-sensitive adhesives must have high cohesive strength and high adhesive strength. It is essential to have both. The cohesive force of this pressure-sensitive adhesive has an important meaning when processing pressure-sensitive adhesive tapes and sheets made using the pressure-sensitive adhesive. That is, pressure-sensitive adhesive tapes are usually first made in a wide state, for example, around 1 meter, and then go through a process of being cut at high speed into practical widths, for example, several centimeters. If the cohesive force of the adhesive is low, the pressure-sensitive adhesive will adhere to the surface of the cutter used for cutting, and the efficiency of the cutting process will be extremely reduced. In addition, pressure-sensitive adhesive sheets are often used after being punched out into letters or other various shapes at the final use stage, and immediately after the punching process, unnecessary parts of the sheet are continuously removed at high speed. However, if the cohesive force of the pressure-sensitive adhesive is low at this time, the pressure-sensitive adhesive layer that has been separated in the punching process will immediately become integrated afterwards, and in the process of removing unnecessary parts of the sheet,
The efficiency of this process will be extremely reduced if necessary parts are removed or continuous unnecessary parts are broken. As mentioned above, the cohesive force of a pressure-sensitive adhesive plays an extremely important role not only in its final use stage, but also in the process of producing pressure-sensitive adhesive tapes and sheets. Therefore, in order to further increase the cohesive force of pressure-sensitive adhesives, for example, when emulsion polymerizing unsaturated monomers such as those mentioned above, internal crosslinking of di- or tri(meth)acrylates of polyhydric alcohols, divinylbenzene, etc. Attempts have been made to copolymerize agents or add external crosslinking agents such as melamine compounds, epoxy compounds, or polyvalent metal salts to aqueous dispersions of polymers obtained by emulsion polymerization. However, although the cohesive force itself can be increased by such a conventionally known method, the adhesive force is greatly reduced, making it difficult to obtain sufficient repulsion resistance as described above. In view of this situation, the present inventors have demonstrated excellent processability when made into pressure-sensitive adhesive tapes and sheets by adding a polyvalent metal compound to a specific aqueous polymer dispersion, and have achieved high cohesive strength and high The inventors have now completed the present invention by discovering that a water-dispersed pressure-sensitive adhesive composition having adhesive strength and excellent repulsion resistance can be obtained. That is, the present invention provides a pressure-sensitive adhesive composition comprising an aqueous polymer dispersion (A) and a polyvalent metal compound (B) shown in the following () as essential components, the pressure-sensitive adhesive composition comprising: The polymer contained in the aqueous polymer dispersion (A) accounts for 50% by weight or more of the total polymer contained in the product, and the polyvalent metal compound (B) )but
The present invention provides a pressure-sensitive adhesive composition characterized in that the proportion is 0.1% equivalent or more. () The content of the unsaturated carboxylic acid (a) in the monomer component system containing the unsaturated carboxylic acid (a) in the largest amount is 2 to 50% by weight, and the unsaturated carboxylic acid (a) A monomer component system in which the difference in the content of the unsaturated carboxylic acid (a) between the monomer component system with the highest content and the monomer component system with the lowest content is 2% by weight or more. Polymer aqueous dispersion (a) obtained by mixing two or more types of polymer aqueous dispersions obtained by emulsion polymerization of each individually, or sequential emulsion polymerization of each of these monomer components An aqueous polymer dispersion obtained by mixing one or more aqueous polymer dispersions obtained by (b) or the aqueous polymer dispersion (a) and the aqueous polymer dispersion An aqueous polymer dispersion (c) obtained by mixing a liquid (b) with a monomer composition of the total polymer containing an unsaturated carboxylic acid (a) of 0.2 to 20% by weight; Acrylic acid alkyl ester (b) whose alkyl group has 4 to 12 carbon atoms 50 to 99.8% by weight and other copolymerizable unsaturated monomers (c) 0 to 49.8% by weight (with the exception of (a), ( The sum of b) and (c) is 100% by weight). The unsaturated carboxylic acid (a) used in obtaining the polymer aqueous dispersion (A) specified in the above paragraph () in the present invention includes unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid. -Basic acids; examples include unsaturated dibasic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid, and monoesters thereof, and one or more of these may be used. The proportion of the unsaturated carboxylic acid (a) in the monomer composition of all the polymers contained in the aqueous polymer dispersion (A) must be 0.2 to 20% by weight. If the amount is less than 0.2% by weight, high cohesive and adhesive strength cannot be obtained when used as a pressure sensitive adhesive;
If the amount exceeds 20% by weight, the adhesive strength will decrease. Examples of acrylic acid alkyl esters (b) in which the alkyl group has 4 to 12 carbon atoms include butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, and isoamyl acrylate. , hexyl acrylate, cyclohexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, etc., and one or more of these alkyl acrylates. can be used. The proportion of the acrylic acid alkyl ester (b) in the monomer composition of all the polymers contained in the aqueous polymer dispersion (A) must be 50 to 99.8% by weight. If it is less than 50% by weight, the adhesive strength and durability of the pressure-sensitive adhesive composition will be reduced, and if it exceeds 99.8% by weight, it will reduce the high cohesive strength necessary to achieve the purpose of the present invention. It is not possible to obtain a pressure sensitive adhesive with Other copolymerizable unsaturated monomers (c) include, for example, aliphatic unsaturated hydrocarbons such as ethylene and butadiene; halogen-substituted aliphatic unsaturated hydrocarbons such as vinyl chloride; styrene, α -Aromatic unsaturated hydrocarbons such as methylstyrene and divinylbenzene; Vinyl esters such as vinyl acetate; Vinyl ethers; Esters of allyl alcohol with various organic acids and ethers with various alcohols; Unsaturated such as acrylonitrile Cyanide compounds; unsaturated amide compounds such as acrylamide; acrylic acid alkyl esters and acrylic acid aryl esters in which the alkyl group has carbon atoms other than 4 to 12; various esters of unsaturated basic carboxylic acids such as methacrylic acid and crotonic acid; Examples include various diesters of unsaturated dibasic carboxylic acids such as maleic acid and fumaric acid, and one or more types selected from these groups can be used. The proportion of the unsaturated monomer (c) in the monomer composition of all the polymers contained in the aqueous polymer dispersion (A) must be 0 to 49.8% by weight. If the amount exceeds 49.8% by weight, the adhesive strength and durability of the pressure-sensitive adhesive composition will decrease. Among the unsaturated monomers (c), unsaturated monomers having two or more radically polymerizable vinyl groups in one molecule, such as di- or tri(meth)acrylates of polyhydric alcohols and divinylbenzene, are generally used. Acts as an internal crosslinking agent, and if the amount used is large, the resulting pressure-sensitive adhesive will show relatively high cohesive strength, but the adhesive strength tends to decrease, so the amount used is the sum of all monomer components. The content is preferably 2% by weight or less. The aqueous polymer dispersion (A) is a polymer obtained by mixing two or more aqueous polymer dispersions obtained by individually emulsion polymerizing each of the specific monomer component systems. Aqueous dispersion (a) or a polymer aqueous dispersion obtained by mixing one or more aqueous polymer dispersions obtained by sequential emulsion polymerization of each of these monomer components (b) or an aqueous polymer dispersion (c) obtained by mixing the aqueous polymer dispersion (a) and the aqueous polymer dispersion (b). Here, the monomer component system used for single emulsion polymerization or sequential emulsion polymerization is the following (i) and (ii).
must satisfy the following conditions. (i) The content of unsaturated carboxylic acid (a) in the monomer component system containing the unsaturated carboxylic acid (a) in the largest amount is 2 to 50% by weight. (ii) The difference in the content of unsaturated carboxylic acid (a) between the monomer component system with the highest content and the monomer component system with the lowest content is 2% by weight. %
A monomer component system group containing the above monomer component systems is required. In condition (i), if the amount of unsaturated carboxylic acid (a) is less than 2% by weight, a pressure-sensitive adhesive having high cohesive strength cannot be obtained, and if the amount exceeds 50% by weight, emulsion polymerization becomes difficult. Also, condition (ii)
The difference in the content of unsaturated carboxylic acid (a) in
If it is less than % by weight, the cohesive force and adhesive force will be poor. In the emulsion polymerization to obtain the aqueous polymer dispersion (A) in the present invention, conventionally known emulsifiers can be used. Examples of anionic emulsifiers include fatty acid salts, higher alcohol sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, naphthalene sulfonic acid formalin condensates, dialkyl group sulfosuccinate ester salts, polyoxyethylene alkyl sulfosuccinate monoester salts, Polyoxyethylene alkyl sulfate salt, polyoxyethylene alkylaryl sulfate salt, polyoxyethylene alkyl phosphate salt, etc.; polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene fatty acid ester as a nonionic emulsifier , sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, oxyethylene oxypropylene block copolymer, fatty acid monoglyceride, and the like. One or more emulsifiers selected from the group of such emulsifiers can be effectively used, and the amount used is preferably in the range of 0.1 to 10% by weight based on the total unsaturated monomers. Note that, if necessary, protective colloids can be used alone or together with an emulsifier, and furthermore, in some cases, it is also possible to obtain an aqueous polymer dispersion without using these emulsifiers or protective colloids at all. Polymerization catalysts for emulsion polymerization of unsaturated monomers include inorganic peroxides such as ammonium persulfate and hydrogen peroxide; organic peroxides such as t-butyl hydroperoxide; and other radical-generating polymers. An initiator or the like may be used, and the amount used is 0.01 to 3 parts by weight, preferably 0.1 to 1 part by weight, per 100 parts by weight of the unsaturated monomer. When using peroxides, if it is necessary to increase the polymerization rate or lower the reaction temperature, reducing agents such as soluble sulfites and ascorbic acid or metals that generate heavy metal ions in water such as ferrous sulfate may be used. The compounds can be combined with peroxides to form redox systems. The emulsion polymerization temperature is appropriately selected depending on the type and composition of the unsaturated monomer, the type of polymerization catalyst, etc.
It is usually in the range of 0 to 100°C. The amount of water during emulsion polymerization is usually 100% of the unsaturated monomer.
The ratio is 300 to 50 parts by weight. The pH of the aqueous polymer dispersion (A) of the present invention thus obtained is usually acidic, but in the present invention, the pH of the aqueous polymer dispersion (A) of the present invention is usually acidic. It can be added before or after mixing with to make it neutral or alkaline before use. The aqueous polymer dispersion (A) is used in such a proportion that the polymer contained in the dispersion (A) is 50% by weight or more based on the total polymer in the pressure-sensitive adhesive composition of the present invention. 50
If the amount is less than % by weight, the adhesive force, cohesive force, repulsion resistance, etc. of the pressure sensitive adhesive will be unsatisfactory. Next, as the polyvalent metal compound (B) in the present invention, one or more types selected from the group consisting of polyvalent metal salts, complexes, chelates, hydroxides, and oxides can be effectively used. used. Examples of polyvalent metals that form such polyvalent metal compounds and are suitable for the present invention include zinc, calcium, magnesium, aluminum, etc. Among these polyvalent metals, zinc is particularly preferred. The amount of the polyvalent metal compound (B) used is 0.1% equivalent or more based on the carboxyl groups in the total polymer contained in the pressure-sensitive adhesive composition. If the amount used is less than 0.1% equivalent, sufficient performance will not be exhibited. The optimum amount to be used within this range is appropriately selected depending on the type and amount of the monomer component used in obtaining the aqueous polymer dispersion (A) and the type of the polyvalent metal compound (B). The polyvalent metal compound (B) can be added to the aqueous polymer dispersion (A) of the present invention in the form of a dispersion in water using a dispersant, a form dissolved in water, or a solid state. can. When the polyvalent metal compound (B) does not substantially dissociate or dissolve in water, it is preferably added in the form of a dispersion in water in order to more strongly exhibit the effects of the present invention. Polyvalent metal compound (B)
Any dispersant that can be used when dispersing solid particles in water can be used, but examples include sodium polyacrylate, sodium naphthalene sulfonate formalin condensate, and diisobutylene. -Maleic acid copolymer etc. or 1 from the following block polymers (1), (2) and (3) as appropriate
A species or two or more species can be used effectively.
The amount of the dispersant used when obtaining the aqueous dispersion of the polyvalent metal compound (B) depends on the type of the dispersant and the polyvalent metal compound (B) and the aqueous dispersion. Although it cannot be specified as it changes depending on the concentration of the polyvalent metal compound (B), it is usually appropriately determined in the range of 0.1 to 20% by weight based on the polyvalent metal compound (B). Block copolymer (1) General formula (However, in the formula, R ₁ and R ₂ each represent hydrogen or a methyl group, m represents an integer from 1 to 100,
and

[Formula] moiety may have different types of repeating structural units bonded randomly. ), one or more monomers selected from polyalkylene glycol mono(meth)allyl ether monomers, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and salts thereof and, if necessary, a monomer copolymerizable with these monomers using a polymerization initiator. Block copolymer (2) General formula (However, in the formula, R ₃ and R ₄ each represent hydrogen or a methyl group, n represents an integer from 1 to 100,
and

[Formula] moiety may have different types of repeating structural units bonded randomly. ), one or more monomers selected from polyalkylene glycol mono(meth)acrylate monomers, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and salts thereof , and, if necessary, a monomer copolymerizable with these monomers using a polymerization initiator. Block copolymer (3) General formula (However, in the formula, p represents an integer of 1 to 4, q and r each independently represent O or an integer of 1 to 100, and R ₅ and R ₆ each independently represent a carbon number of 2 to 4.
represents an alkylene group, and Y and Z each independently represent a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms,
Monovalent phosphoric acid group (However, monovalent metal, divalent metal, ammonia or organic amine salt, or carbon number 1
Contains mono- or diesters of ~4 alkyl groups. ), monovalent sulfonic acid group (however, monovalent metal, divalent
It includes salts of valent metals, ammonia or organic amines, or esters of alkyl groups having 1 to 4 carbon atoms. ), or a monovalent sulfate group (including salts of monovalent metals, divalent metals, ammonia or organic amines, or esters of alkyl groups having 1 to 4 carbon atoms).
or Y and Z together represent a divalent phosphoric acid group, a divalent sulfonic acid group, or a divalent sulfuric acid group. ) Allyl ether monomer represented by
One or more monomers selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and salts thereof, and if necessary, a monomer copolymerizable with these monomers. obtained by copolymerizing polymers using a polymerization initiator. The pressure-sensitive adhesive composition of the present invention thus obtained can be used as a pressure-sensitive adhesive as it is, but various additives as shown below may be added as necessary. Can be done. First, if it is necessary to further increase the adhesive strength of the pressure-sensitive adhesive composition of the present invention, use a tackifier resin with a softening point of about 60°C or higher, such as rosin resin, petroleum resin resin, coumaron inden type resin, phenolic resin, etc. in the polymer aqueous dispersion (A).
60 parts by weight or less, preferably 5 parts by weight per 100 parts by weight
It can be added in the range of ~40 parts by weight. If it is necessary to increase the adhesive strength, liquid tackifying resin, low molecular weight polymer with an average molecular weight of 8000 to 20000,
Plasticizers and the like can be added. In addition, if it is necessary to further increase the cohesive force of the pressure-sensitive adhesive composition of the present invention, an aqueous polymer dispersion may be added.
An epoxy compound, melamine compound, isocyanate compound, etc. that can act as an external crosslinking agent is added in an aqueous solution, aqueous dispersion or organic solvent solution in the range of 0.005 to 2 parts by weight per 100 parts by weight of the polymer in (A). It can also be added in the form of The pressure-sensitive adhesive composition of the present invention may further contain an antifoaming agent, a thickener, a viscosity modifier, a coloring agent,
Known additives such as fillers and anti-aging agents may also be added. Note that some thickeners are polymers having a large number of carboxyl groups and exhibit a thickening effect when alkali is added, but the use of such thickeners does not impair the effects of the present invention. In fact, more favorable results may be obtained. The pressure-sensitive adhesive composition of the present invention thus obtained has both high cohesive strength and high adhesive strength, and this cohesive strength does not significantly decrease even at relatively high temperatures, and therefore can be used over a wide temperature range. In addition to exhibiting excellent repulsion resistance over a long period of time, it also exhibits good adhesion and repulsion resistance to non-polar substrates such as polyethylene and polypropylene, which are generally difficult to adhere to. It can be applied to various purposes, and can be particularly effectively used for pressure-sensitive adhesive tapes and sheets. Although it is not yet clear why such effects obtained by the pressure-sensitive adhesive composition of the present invention are based on, it is clear that the pressure-sensitive adhesive composition of the present invention is dried on a substrate The resulting adhesive layer is formed by bonding the carboxyl groups in the polymer having a relatively large number of carboxyl groups with the polyvalent metal compound (B) or the polyvalent metal ions generated from the polyvalent metal compound (B). , which can contribute to the expression of high cohesive force 3
2-dimensional network structure, and the network structure is filled with a polymer that does not contain carboxyl groups or has a relatively small amount of carboxyl groups and can contribute to the expression of high adhesive strength. It is assumed that this is due to the following. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, unless otherwise specified, in the examples, parts by weight are meant, and % means % by weight. Reference Example 1 First, two types of unsaturated monomer aqueous emulsions shown below were prepared. : Butyl acrylate 180 parts, vinyl acetate 16 parts,
4 parts of acrylic acid, 2 parts of polyoxyethylene nonyl phenyl ether sulfate ammonium salt (average number of added moles of ethylene oxide: 4),
Unsaturated monomer aqueous emulsion obtained by mixing and stirring 8 parts of a polyoxyethylene adduct of a secondary alcohol having 12 to 14 carbon atoms (Nippon Shokubai Chemical Co., Ltd., Softanol 200) and 80 parts of deionized water.
290 copies. : 180 parts of butyl acrylate, 4 parts of vinyl acetate,
16 parts of acrylic acid, 2 parts of polyoxyethylene nonyl phenyl ether sulfate ammonium salt (average number of added moles of ethylene oxide: 4),
An unsaturated monomer aqueous emulsion obtained by mixing and stirring 8 parts of a polyoxyethylene adduct of a secondary alcohol having 12 to 14 carbon atoms (Nippon Shokubai Chemical Co., Ltd., Softanol 200) and 80 parts of deionized water.
290 copies. 246 parts of deionized water was charged into a glass flask equipped with a stirrer, a thermometer, a dropping funnel, a nitrogen gas inlet, and a reflux condenser, and the flask was purged with nitrogen. The temperature was then raised to 55°C, 30 parts of the above unsaturated monomer aqueous emulsion was added, and the mixture was stirred at 55°C for 10 minutes. Polymerization was initiated by the addition of 1 part of a 10% aqueous solution. 10 minutes after the start of polymerization, the reaction temperature was increased to 70°C.
The remainder of the unsaturated monomer aqueous emulsion is kept at °C.
260 parts and in parallel 4 parts of a 10% aqueous solution of sodium bisulfite were added continuously at a uniform rate over 50 minutes to advance emulsion polymerization. Then, after continuing to mix and stir at 70℃ for 30 minutes, the reaction temperature was lowered.
While maintaining the temperature at 70.degree. C., an aqueous unsaturated monomer emulsion and, in parallel, 5 parts of a 10% aqueous solution of sodium bisulfite were added continuously at a uniform rate over 70 minutes to proceed with emulsion polymerization. Then 60 at 70℃
After completing the polymerization by continuing mixing and stirring for a minute and cooling it to room temperature, ammonia water was added, and the pH was set to 7.0.
An aqueous polymer dispersion (1) with a solid content of 48.8% was obtained. Reference Example 2 290 parts of each of the same unsaturated monomer aqueous emulsions as used in Reference Example 1 were prepared, and each was subjected to emulsion polymerization by the method shown below. 116 parts of deionized water was charged into a glass flask equipped with a stirrer, a thermometer, a dropping funnel, a nitrogen gas inlet, and a reflux condenser, and the flask was purged with nitrogen. Then, the temperature was raised to 55°C, and the above unsaturated monomer aqueous emulsion was
After adding 15 parts out of 290 parts and stirring at 55°C for 10 minutes, 5 parts of a 20% aqueous solution of ammonium persulfate and 0.5 part of a 10% aqueous solution of sodium bisulfite were added to initiate polymerization. 10 minutes after the start of polymerization, the reaction temperature was increased to 70°C.
The remainder of the unsaturated monomer aqueous emulsion is kept at °C.
Emulsion polymerization was proceeded by continuously adding 275 parts and 4.5 parts of a 10% aqueous solution of sodium bisulfite at a uniform rate over 120 minutes. Then, mixing and stirring were continued for 60 minutes at 70°C to complete polymerization. Ammonia water was added to a mixture of equal amounts of the two types of polymer aqueous dispersions obtained, and the pH was adjusted.
7.1, an aqueous polymer dispersion (2) having a solid content of 49.7% was obtained. Reference Example 3 Composition obtained by combining the unsaturated monomer aqueous emulsion used in Reference Example 1, that is, butyl acrylate 360
20 parts of vinyl acetate, 20 parts of acrylic acid, 4 parts of polyoxyethylene nonyl phenyl ether sulfate ammonium salt (average number of added moles of ethylene oxide: 4), polyoxyethylene adduct of secondary alcohol having 12 to 14 carbon atoms (Nippon Shokubai Chemical Co., Ltd., Softanol 200) 16 parts and deionized water
580 parts of an aqueous unsaturated monomer emulsion consisting of 160 parts was prepared. A glass flask equipped with a stirrer, a thermometer, a dropping funnel, a nitrogen gas inlet, and a reflux condenser was charged with 246 parts of deionized water, and the flask was purged with nitrogen. The temperature was then raised to 55°C, 30 parts of the above unsaturated monomer aqueous emulsion was added, and the mixture was stirred at 55°C for 10 minutes. % aqueous solution was added to initiate the polymerization. 10 minutes after the start of polymerization, the remaining 550 parts of the unsaturated monomer aqueous dispersion and 9 parts of a 10% aqueous solution of sodium bisulfite were added over a period of 120 minutes while maintaining the reaction temperature at 70°C. Emulsion polymerization was allowed to proceed by adding continuously at a uniform rate. Next, mixing and stirring were continued for 60 minutes at 70° C. to complete polymerization, and then the mixture was cooled to room temperature, and aqueous ammonia was added to obtain an aqueous polymer dispersion (3) having a pH of 6.9 and a solid content of 49.8%. Reference Example 4 First, three types of unsaturated monomer aqueous emulsions shown below were prepared. : 144 parts of an aqueous unsaturated monomer emulsion obtained by mixing and stirring 60 parts of 2-ethylhexyl acrylate, 40 parts of ethyl acrylate, 1 part of sodium dodecylbenzenesulfonate, and 43 parts of deionized water. : 144 parts of an unsaturated monomer aqueous emulsion obtained by mixing and stirring 50 parts of 2-ethylhexyl acrylate, 47 parts of ethyl acrylate, 3 parts of acrylic acid, 1 part of sodium dodecylbenzenesulfonate, and 43 parts of deionized water. . : 144 parts of an unsaturated monomer aqueous emulsion obtained by mixing and stirring 40 parts of 2-ethylhexyl acrylate, 54 parts of ethyl acrylate, 6 parts of acrylic acid, 1 part of sodium dodecylbenzenesulfonate, and 43 parts of deionized water. . A glass flask equipped with a stirrer, a thermometer, a dropping funnel, a nitrogen gas inlet, and a reflux condenser was charged with 163.5 parts of deionized water, and the flask was purged with nitrogen. Then, the temperature was raised to 55°C, 21.6 parts of the above unsaturated monomer aqueous emulsion was added, and after stirring at 55°C for 10 minutes, 7.5 parts of a 20% aqueous solution of ammonium persulfate was added.
0.7 parts and 10% aqueous solution of sodium bisulfite
1 part was added to initiate polymerization. 10 minutes after the start of polymerization, the reaction temperature was increased to 70°C.
The remainder of the unsaturated monomer aqueous emulsion is kept at °C.
122.4 parts and in parallel 1.8 parts of a 10% aqueous solution of sodium bisulfite were added continuously at a uniform rate over 50 minutes to advance emulsion polymerization.
Then, after continuing to mix and stir at 70°C for 30 minutes, while maintaining the reaction temperature at 70°C, the unsaturated monomer aqueous emulsion and, in parallel, 10% of sodium bisulfite were added.
% aqueous solution was continuously added at a uniform rate over 60 minutes to proceed with emulsion polymerization. Then 70
After continuing mixing and stirring at ℃ for 30 minutes, the reaction temperature was increased to 70℃.
unsaturated monomer aqueous emulsion and in parallel a 10% aqueous solution of sodium bisulfite while keeping
Emulsion polymerization was carried out by continuously adding 2.5 parts at a uniform rate over 60 minutes. Next, continue mixing and stirring at 70°C for 60 minutes to complete polymerization, cool to room temperature, and add aqueous ammonia to adjust the pH to 7.0.
An aqueous polymer dispersion (4) with a nonvolatile content of 49.8% was obtained. Reference Example 5 Polyethylene glycol monoallyl ether (containing an average of 2 ethylene oxide units per molecule) was placed in a glass reaction vessel equipped with a thermometer, stirrer, dropping funnel, gas introduction tube, and reflux condenser.
334 parts and 100 parts of water were charged, and the inside of the reaction vessel was purged with nitrogen while stirring, and heated to 95°C in a nitrogen atmosphere.
Thereafter, an aqueous solution of 139.3 parts of maleic acid and 14.2 parts of ammonium persulfate dissolved in 225 parts of water was added over 120 minutes. After the addition was completed, 14.2 parts of a 20% aqueous ammonium persulfate solution was further added over 20 minutes. After completing the addition,
The temperature inside the reaction vessel was maintained at 95° C. for 100 minutes to complete the polymerization reaction, and a block copolymer (1) was obtained. A 55% aqueous solution of this copolymer (1) had a pH of 1.1 and a viscosity of 136 cps. The polymerization rate was 97.8%.
Further, the molecular weight of this copolymer (1) was 1800, and the acid value was 285. Next, a 40% aqueous sodium hydroxide solution was added to neutralize the mixture to obtain an aqueous sodium salt solution of copolymer (1). The sodium salt of this copolymer (1)
The 45% aqueous solution had a pH of 8.2 and a viscosity of 203 cps. Reference Example 6 Place 20 parts (solid content equivalent) of the block copolymer (1) obtained in Reference Example 5 in a stainless steel beaker, and add water.
180 parts were added to obtain an aqueous dispersant solution. Glass beads (manufactured by Toshiba, "GB-503M") are added to this dispersant aqueous solution.
After adding 300 parts, 200 parts of activated zinc white (wet method zinc white, manufactured by Sakai Chemical Industry Co., Ltd.) was added over 10 minutes while stirring with a Lab Disper (manufactured by Tokushu Kika Kogyo Co., Ltd., "MR-L type"). . After the addition was completed, stirring was continued for an additional 30 minutes to obtain a zinc oxide aqueous dispersion (1) with a pH of 8.3. Reference Example 7 Block copolymer (1) used in Reference Example 6
20 parts (solid content equivalent) of low molecular weight sodium polyacrylate (manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd., Aqualic)
A zinc oxide aqueous dispersion (2) with a pH of 8.4 was obtained in exactly the same manner as in Reference Example 6, except that the dispersion was changed to DL-40). Examples 1 to 12, Comparative Examples 3 to 6 Polymer aqueous dispersions (1) obtained in Reference Examples 1 to 4
To 100 parts of each of (4), the zinc compounds shown in Table 1 were added in the amounts shown in Table 1 and mixed uniformly to prepare a pressure-sensitive adhesive composition. Comparative Examples 1, 2, 7, 8 Polymer aqueous dispersions (1) obtained in Reference Examples 1 to 4
Each of (4) was used as a pressure-sensitive adhesive composition without adding anything else. The adhesive force, holding force (cohesive force), and repulsion resistance of the pressure-sensitive adhesive compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 8 were measured by the methods shown below. The results are shown in Table 1. <Adhesive strength> A pressure-sensitive adhesive composition is applied to one side of a polyester film with a thickness of 25μ so that the thickness after drying is 45μ, and dried at 105℃ for 3 minutes to make a pressure-sensitive adhesive tape. The 180° peel adhesive strength (g/25mm) was measured using Z-0237. <Holding force> A pressure-sensitive adhesive tape similar to the adhesive force test was made,
Measurement was carried out under a load of 1 kg at 40°C and 80°C in accordance with JIS Z-0237. <Repulsion resistance> Pressure-sensitive adhesive composition is applied to release paper so that the thickness after drying is
Apply to a thickness of 60μ, dry at 105℃ for 3 minutes,
This material was transferred onto both sides of a rayon nonwoven fabric (14 g/m ² ) to make a double-sided adhesive tape with a tape thickness of 130 μm. Cut this double-sided adhesive tape to a size of 20 mm wide and 110 mm long, wrap it around a 50 mmφ stainless steel pipe, and tape it to a size of 15 mm wide and 100 mm long on the outside.
Stainless steel sheets with a thickness of 0.15 mm and a thickness of 0.15 mm were bonded together, and the state of the stainless steel sheets springing up after 24 hours at 70°C was observed. Those with no splashing were considered to be passed.

[Table] What was done.

Claims (1)

[Scope of Claims] 1. Polymer aqueous dispersion (A) shown in the following ()
and a polyvalent metal compound (B) as essential components, wherein the pressure-sensitive adhesive composition contains an aqueous polymer dispersion (A) in all the polymers contained in the pressure-sensitive adhesive composition. The polymer accounts for 50% by weight or more, and the polyvalent metal compound (B) is
A pressure-sensitive adhesive composition characterized in that the proportion is 0.1% equivalent or more. (Note) () The content of unsaturated carboxylic acid (a) in the monomer component system containing the unsaturated carboxylic acid (a) in the largest amount is 2 to 50% by weight, and A monomer in which the difference in the content of the unsaturated carboxylic acid (a) between the monomer component system with the highest content of (a) and the monomer component system with the lowest content is 2% by weight or more Polymer aqueous dispersion (a) obtained by mixing two or more types of polymer aqueous dispersions obtained by individually emulsion polymerizing each of the component systems, or each of these monomer components An aqueous polymer dispersion (b) obtained by mixing one or more aqueous polymer dispersions obtained by subsequent emulsion polymerization, or an aqueous polymer dispersion (a) and the aqueous polymer dispersion (a). A polymer aqueous dispersion (c) obtained by mixing the combined aqueous dispersion (b), wherein the monomer composition of all the polymers contained is an unsaturated carboxylic acid (a) of 0.2 to 20 50 to 99.8% by weight of an acrylic acid alkyl ester (b) whose alkyl group has 4 to 12 carbon atoms and 0 to 49.8% by weight of other copolymerizable unsaturated monomers (c) (with the exception of (a) ), (b) and (c) are 100% by weight).