JPH0576513B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention particularly relates to water-dispersed resin compositions for adhesive applications. [Conventional technology] Conventional adhesives are made by masticating various rubbers such as natural rubber and synthetic rubber whose molecular weight has been reduced to a level that makes them soluble in solvents, and then adding tackiness and adhesion to polyolefins, especially polyethylene. In order to provide this, a mixture of tackifying resins such as rosin, rosin derivatives, terpene resins, synthetic petroleum resins, etc. was commonly used. The various components that make up the adhesive are mixed uniformly,
In order to impart appropriate fluidity to the adhesive and obtain good coating suitability, the adhesive coating solution contains 50 to 80% by weight of an organic solvent such as toluene or hexane. After applying the adhesive coating liquid to the base material such as paper or film,
By evaporating the organic solvent with hot air or the like, a dry coating film (adhesive) having an adhesive function is formed. Organic solvents contained in adhesive coating liquids are volatile and flammable, so use of organic solvents is prohibited during storage,
There are problems such as fire danger, occupational health problems, and air pollution in the coating and drying processes. Therefore, the use of polymer aqueous dispersions (latex) using water as a dispersion medium has gained momentum, and rubber
Aqueous dispersions of combinations of tackifying resins are being developed (Japanese Patent Publications No. 26545, No. 55-48270, No.
58-160378, Japanese Patent Publication No. 58-183771). A mixture of synthetic rubber latex and tackifying resin aqueous dispersion is prepared by adding tackifying resin to 100 parts by weight of latex polymer.
A composition containing 50 to 100 parts by weight is common;
Although it shows good adhesive properties at a measurement temperature of ~23°C, a satisfactory value for adhesive strength at 0°C is not obtained. In addition, there are some rubber latex polymers that can obtain adhesive properties only in the absence of a tackifying resin (Japanese Patent Application Laid-Open No.
145909, Japanese Unexamined Patent Publication No. 57-57707). However, in this case, the adhesive strength to polyethylene was extremely low. [Problems to be Solved by the Invention] It is essential that the adhesive has the ability to strongly adhere to general-purpose materials with a small pressure within a wide temperature range (0 to 40°C). However, in particular, conventional water-dispersed adhesives have cohesive strength at 40°C (high-temperature cohesive strength), adhesive strength at 0°C (low-temperature adhesiveness), and adhesive strength with polyethylene, which is particularly difficult to adhere to among general-purpose materials ( There was no material that fully satisfied all three physical properties of adhesion (PE adhesion). In general, synthetic latex polymers used in adhesives have a distribution of molecular weights, with high molecular weight toluene-insoluble parts (gel parts) providing cohesive strength to the adhesive, and low-molecular weight toluene-soluble parts (insoluble parts). gel content) gives the adhesive fluidity, i.e., tackiness.
It has the effect of providing PE adhesive properties. However, in designing latex polymers,
When the gel content is increased (eg, adjusted to 50-70% by weight) to provide the necessary high-temperature cohesion, the fluidity of the non-gel portion of the polymer alone provides little PE adhesion. Therefore, adding 50 to 100 parts of tackifying resin to 100 parts of polymer usually provides the required amount.
An adhesive exhibiting PE adhesion is obtained. However, since tackifying resins are generally used that have a softening point of 50 to 100°C, the physical properties at low temperatures of the mixed adhesive of latex polymer and tackifying resin are impaired, resulting in a decrease in low-temperature tack. . When a tackifying resin with a low softening point or a polymer with a low glass transition temperature is used, low temperature tackiness is good, but high temperature cohesive strength is reduced. In other words, it is extremely difficult to achieve a balance between high-temperature cohesive strength, low-temperature tackiness, and PE adhesiveness with a tackifier that is a mixture of synthetic latex and tackifying resin aqueous dispersion. [Means and effects for solving the problem] The present inventors have obtained a water-dispersible adhesive coating liquid that sufficiently satisfies the three physical properties of high-temperature cohesion, low-temperature tackiness, and PE adhesiveness described above. If you can,
It has become possible to replace solvent-based adhesive coating fluids,
We have made it possible to manufacture adhesive tapes that are safe from health and safety concerns, and we have considered this to be extremely meaningful from an industrial perspective, and have therefore conducted extensive research. As a result, a specific water consisting of a water-dispersed polymer (a) having a specific gel content and glass transition temperature and one or more higher organic acids (b) having at least one carboxyl group in one molecule is obtained. It has been discovered that the adhesive of the dispersed resin composition has an excellent adhesive function that satisfies the three adhesive properties described above at the same time, and the present invention has been achieved. The present invention consists of 100 parts by weight of a water-dispersed polymer (a) having a gel content of 20 to 70% by weight and a glass transition temperature of -20°C or lower, and a higher organic acid (b) having at least one carboxyl group in one molecule. 0.5 to 30 parts by weight of one or more of A water-dispersed resin composition for adhesives is characterized in that: The present invention will be explained in detail below. The water-dispersed polymer (a) used in the present invention can be obtained by emulsion polymerization of one or more monomers containing at least one radically polymerizable unsaturated group. The proportion of soft monomer in the water-dispersed polymer (a) used in the present invention is 50 to 90% by weight. Soft monomer refers to a monomer with a homopolymer glass transition temperature of -20°C or lower, specifically (meth)acrylic esters such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and lauryl methacrylate; butadiene , isoprene, chloroprene, and other conjugated dienes. The water-dispersed polymer (a) can contain as a component a monomer (hard monomer) that is copolymerizable with a soft monomer and whose homopolymer glass transition temperature exceeds -20°C. Typical examples of hard monomers include methyl (meth)acrylate,
(Meth)acrylic acid esters such as lauryl acrylate and ethyl methacrylate; aromatic vinyl compounds such as styrene, vinyltoluene, α-methylstyrene, and divinylbenzene; ethylenically unsaturated compounds such as acrylic acid, methacrylic acid, itaconic acid, and fumaric acid Carboxylic acids; hydroxyalkyl esters such as 2-hydroxyethyl acrylate and hydroxypropyl methacrylate; vinyl compounds having glycidyl groups such as glycidyl methacrylate and glycidyl acrylate; acrylamide;
Compounds having an amide group such as N-methylolacrylamide; vinyl esters such as vinyl acetate and vinyl propionate; dioctyl maleate, dioctyl fumarate, dimethylaminoethyl methacrylate, acrylonitrile, and the like. The glass transition temperature (Tg) of water-dispersed polymer (a) is
The temperature is -20°C or lower, preferably -80°C to -30°C.
When Tg exceeds -20°C, low-temperature tackiness decreases, making it likely to be unsuitable for adhesive applications. Further, the gel content of the water-dispersed polymer (a) is 20 to 70% by weight. For adhesive applications, if the gel content is less than 20% by weight, high-temperature cohesive strength cannot be obtained, and if it exceeds 70% by weight, low-temperature tack and PE adhesion cannot be obtained. The gel content of the water-dispersed polymer (a) can be adjusted as appropriate by adjusting the type and amount of the chain transfer agent, polymerization temperature, polymerization rate, average particle size of the latex, type and amount of the crosslinking agent, etc. As the chain transfer agent, known chain transfer agents such as mercaptans and carbon tetrachloride can be used. If the amount of the chain transfer agent used is too large, the gel content will be reduced, and if it is too small, the gel content will be increased. Gel content adjustment by polymerization temperature, polymerization rate, and average particle size of latex is as well known in ordinary emulsion polymerization.
The higher the polymerization temperature and polymerization rate, and the smaller the average particle size of the latex, the more the gel content can be increased. Examples of the crosslinking agent include crosslinking monomers such as divinylbenzene and glycidyl methacrylate, compounds having two or more glycidyl groups in one molecule, and common crosslinking agents such as sulfur. The crosslinking monomer is used by being added together with other monomers during emulsion polymerization, and the usual crosslinking agent is added after the polymerization is completed. The amount of crosslinking agent added is usually determined by the monomer or polymer.
The gel content can be adjusted by using 0.5 to 5 parts by weight per 100 parts by weight. The higher organic acid (b) used in the present invention contains one or more carboxyl groups in one molecule, and has a specific
Refers to substances that can become a transparent aqueous solution (hereinafter referred to as "completely dissolved") at pH levels or higher. Further, the solubility of the higher organic acid (b) in pure water at 25° C. is preferably 0.5 g/100 g water or less. If the solubility in water exceeds 0.5 g/100 g water, it is not preferable because not only the adhesive properties of the adhesive but also the water resistance deteriorate. The dissociation constant pKa of the higher organic acid (b) is preferably 3.0 to 9.0. A higher organic acid (b) having a pKa within this range is preferable because it can be insolubilized within a pH range that does not impair the stability of the latex particles. Specifically, preferred are resin acids such as rosin acid, higher fatty acids such as oleic acid and lauric acid, and higher organic acids such as synthetic petroleum resins modified with unsaturated carboxylic acids such as acrylic acid, fumaric acid and maleic acid. The higher organic acid used in the present invention is neutralized with alkali metal ions and/or ammonium ions and completely dissolves in water to form an aqueous solution at a certain pH or higher, but begins to become insoluble in water below a certain pH. ,
A precipitate of higher organic acid (b) is formed. A specific pH (hereinafter referred to as
The PH (expressed as "specific PH") varies depending on the type of higher organic acid and cannot be limited, but it is generally located approximately between PH 8.0 and 11.0. The molecular weight of the higher organic acid (b) is preferably 100 to 2,000.
If the molecular weight is less than 100, it is not preferable because not only the adhesive properties of the adhesive but also the water resistance deteriorate.
In addition, when the molecular weight exceeds 2000, water-dispersed polymer (a)
The compatibility with the adhesive deteriorates and the adhesive properties are impaired. The proportion of the higher organic acid (b) is preferably 0.5 to 30 parts by weight per 100 parts by weight of the water-dispersed polymer (a). More preferably, it is 1.0 to 20 parts by weight. If it is less than 0.5 part by weight, it will not function as a tackifying resin,
The balance between high temperature cohesion, constant temperature adhesion and PE adhesion cannot be achieved. Furthermore, if the amount exceeds 30 parts by weight, not only the low-temperature tackiness decreases to a practically unacceptable level, but also the heat resistance and light resistance become extremely insufficient. It is believed that the higher organic acid (b) is well compatible with the water-dispersed polymer (a) and functions as a tackifying resin that promotes the fluidity of the polymer. The proportion of the higher organic acid (b) dissolved in the aqueous phase of the water-dispersed resin composition must be 35% or less based on the total dry weight of (b) in terms of final resin. More preferably 30% or less, most preferably 25% or less. If the proportion of the higher organic acid (b) dissolved in the aqueous phase of the water-dispersed resin composition exceeds 35%, it will act as an emulsifier, which will not only impair its function as a tackifying resin. The water-dispersed resin composition tends to foam, resulting in poor workability during coating and significantly poor water resistance as an adhesive. Surprisingly, in the present invention, the proportion of the higher organic acid (b) dissolved in the aqueous phase of the water-dispersed resin composition is 35%.
Only in the following cases, sufficient PE adhesion can be obtained as an adhesive by adding a small amount of the higher organic acid (b), and the low-temperature adhesiveness is not impaired and the high-temperature cohesive strength is also high. This made it possible for the first time to balance the three physical properties of adhesion mentioned above. This is thought to be due to a portion of the higher organic acid (b) being incorporated into the latex particles and/or on the surface of the particles, and being well dispersed or compatible with the water-dispersed polymer (a). Therefore, even if the amount of (b) is small, it seems to work effectively as a tackifying resin. The water-dispersed resin composition of the present invention is obtained through the following steps. First, an aqueous solution of the higher organic acid (b) completely dissolved at a specific pH or higher is added and mixed before, during and/or after the emulsion polymerization step of the water-dispersed polymer (a). When adding, it is desirable to previously adjust the pH of the emulsion polymerization system or water-dispersed polymer (a) dispersion system to a specific pH or higher in which the higher organic acid (b) can be completely dissolved using caustic potash, ammonia, or the like. Then, during and after the addition of the aqueous solution of the higher organic acid (b), addition of the acid monomer and/or
Alternatively, the water-dispersed resin composition of the present invention can be obtained by gradually lowering the pH of the emulsion polymerization system or the water-dispersed polymer (a) dispersion system by volatilization of ammonia or the like. The final pH of the water-dispersed resin composition is at least below a specific pH, and the proportion of the higher organic acid (b) dissolved in the aqueous phase of the water-dispersed resin composition is
The pH is 35% or less of the total amount of (b). When the PH of the water-dispersed resin composition exceeds the above-mentioned PH,
The percentage of higher organic acid (b) dissolved in the aqueous phase is 35%.
The present invention cannot be achieved beyond this point. Emulsion polymerization methods using aqueous solutions of emulsifiers such as potassium rosinate and potassium oleate are already known. For example, the above-mentioned emulsifier is lowered to a certain pH level to temporarily lose its emulsifying function, destabilizing the latex particles and promoting aggregation and enlargement, and after the particles have aggregated and enlarged, the pH is raised again and the emulsifier There is a method of restoring the emulsifying function of the latex to its original state and contributing to the stabilization of the latex particles, but this polymerization method uses the above-mentioned emulsifier to function as an emulsifier, and after increasing the particle size, the pH must be adjusted again. In order to restore the original function as an emulsifier and stabilize latex particles, attempts to utilize the function of resins such as rosin acid and oleic acid, such as the water-dispersed resin composition of the present invention, have been proposed. There wasn't any (Rubber)
and Plastics Age 42 , 868 (1961), Japanese Patent Application Publication No. 1977-
32084). Even if various anti-aging agents, ultraviolet absorbers, pigments, fillers, crosslinking agents, plasticizers, thickeners, etc. are added to the water-dispersed resin composition of the present invention, the water-dispersed resin of the present invention The composition is not limited.
However, care must be taken to ensure that the proportion of the higher organic acid (b) dissolved in the aqueous phase of the water-dispersed resin composition does not reach a pH of 35% or more due to the additives. The water-dispersed resin composition of the present invention can also be used for coated paper, carpet lining, paint, wallpaper, floor tiles, wood, cement mortar, and the like. The proportion of the higher organic acid (b) dissolved in the aqueous phase of the water-dispersed resin composition is quantified by the following method. While adjusting the pH of the water-dispersed resin composition to 3 or less with 1N hydrochloric acid, dilute and adjust the solid content to 25% with water. Add 100ml of the diluted solution to PH12 with 0.5N potassium hydroxide aqueous solution.
Obtain a neutralization titration curve and check the inflection point (neutralization point). Next, using 1N hydrochloric acid or 0.5N potassium hydroxide, prepare a 25% concentration water-dispersed resin composition at the pH of each neutralization point confirmed above, and have an oval pore diameter of 200 Å in short axis and 2000 Å in major axis. Each 25% concentration water-dispersed resin composition using an ultrafiltration membrane.
Ultrafiltrate 100 ml of the aqueous phase and separate the aqueous phase liquid at each neutralization point. Among the hydrophilic substances dissolved in the aqueous phase liquid for each neutralization point, higher organic acids (b) were confirmed using gel permeation chromatography and infrared spectrophotometer. (b) Determine the PH region to be neutralized. In the neutralization titration curve described above, the amount of potassium hydroxide aqueous solution (a) in the PH range that neutralizes the higher organic acid (b) that has become clear is determined. Dilute the water-dispersed resin composition concentration to 25% while ensuring that there is no change in pH. Using the ultrafiltration membrane described above, half of the aqueous phase of 100 ml of the diluted water resin composition is subjected to ultrafiltration to obtain an aqueous phase liquid. The obtained aqueous phase liquid is adjusted to pH 3 or less with 1N hydrochloric acid, and then titrated to pH 12 with 0.5N aqueous potassium hydroxide solution. Similarly, in the neutralization titration curve obtained, the amount of potassium hydroxide aqueous solution (b) required to neutralize the curve part in the PH range where the higher organic acid is neutralized is determined. The double value of (b) expressed as a percentage of (a) is the ratio of higher organic acid (b) dissolved in the aqueous phase. [Effects of the Invention] The water-dispersed resin composition of the present invention simultaneously satisfies the three adhesion properties of high-temperature cohesive strength, low-temperature tackiness, and PE adhesion that have not been obtained with conventional water-dispersed type adhesives,
It has reached a level where it can replace conventional natural rubber-based organic solvent type adhesives. Thereby,
This not only prevents the disadvantages of adhesive coating fluids containing organic solvents, such as the risk of fire, deterioration of the working environment, and the occurrence of pollution, but also improves the equipment, labor, and labor required to recover solvents.
It also eliminates the need for energy, making it possible to save resources and save energy. In addition, compared to conventional mixtures of synthetic latex and tackifying resin aqueous dispersion, since no tackifying resin aqueous dispersion is used, the emulsifier that was required when dispersing the tackifying resin in water is no longer required, and the adhesive Improves water resistance. Furthermore, since water dispersion equipment and processes are not required, it has become possible to provide an inexpensive adhesive. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 After replacing the inside of a temperature-adjustable pressurized reactor (autoclave) equipped with a dropping funnel and a stirrer with nitrogen in advance, 100 parts by weight of water (hereinafter, all parts are shown in parts) was prepared.
However, all amounts other than water, monomers, and chain transfer agents refer to parts by dry weight). Potassium rosin acid (average molecular weight)
334), 0.2 part of sodium lauryl sulfate, and 0.05 part of ethylenediaminetetraacetic acid sodium salt, and heated to 80°C with stirring. Next, 100 parts of a monomer consisting of 19.5 parts of styrene, 50 parts of butadiene, 25 parts of 2-ethylhexyl acrylate, 5 parts of 2-hydroxyethyl acrylate, and 0.5 part of acrylic acid was added.
and chain transfer agent (tert-dodecyl mercaptan)
1.5 parts of the mixture was added dropwise into the reactor over 8 hours. In addition, an aqueous solution in which 1.2 parts of sodium persulfate, 0.3 parts of caustic soda, and 0.3 parts of sodium dodecylbenzenesulfonate were dissolved in 20 parts of water was added dropwise to the reactor over 9 hours, and the mixture was further heated while maintaining the internal temperature at 80°C. Stirred for 1 hour. PH at the end of polymerization is 6.3,
The polymerization rate was 95%, and a water-dispersed resin composition with an average particle size of 0.19 μm was obtained. After the polymerization was completed, the pH of the resulting water-dispersed resin composition was adjusted to 8.0 using a Kaseizota, and steam stripping was performed to remove residual monomers. Water-dispersed polymer in the obtained water-dispersed resin composition
(a) had a glass transition temperature of -63°C and a gel content of 43%. The obtained water-dispersed resin composition was increased in viscosity to about 10,000 cps by adding about 0.5 part of polyacrylic acid seeder, and after uniformly coating it on release paper at a coating weight of about 45 dry g/ ^m2 , It was dried with hot air at 120°C for 2.5 minutes. The resulting dried coating film on the release paper was pressed onto the corona discharge treated surface of a stretched polypropylene film (thickness: approximately 60 μm), and the dried coating film was transferred to the polypropylene film to prepare an adhesive sample. Adhesive sample at temperature 23
After curing for 1 hour at 65% relative humidity, the following adhesive properties were measured. The results are shown in Table 4. Physical property measurement items and methods: High temperature cohesive force: 25mm sticky sample on a stainless steel plate
× 25mm in size and pasted with a 2kg roller going back and forth once, the adhesive surface was set parallel to the tensile direction of the tensile tester, and the temperature was 2mm/min in an atmosphere of 40℃.
The shear force was measured at a speed of . Low-temperature adhesion: Make a loop with the adhesive layer of an adhesive sample 25 mm wide and 250 mm long, and
It is brought into contact with the cardboard surface at a speed of 500 mm/min under almost zero pressure in an atmosphere at ℃. Three seconds after contact, the adhesive strength was measured when peeled off at the same speed of 500 mm/min. PE adhesion: In an atmosphere of 23°C, a 25 mm wide adhesive sample was pasted on a low density PE plate without additives by one round trip with a 2 kg roller, and after 20 minutes had passed, a 50 mm wide /min
The 180° peel strength was measured at a speed of . The glass transition temperature and gel content of the water-dispersed polymer (a) are measured as follows. After raising the pH to 12 with 0.5N potassium hydroxide,
Half of the aqueous phase of the water-dispersed resin composition diluted to 10% concentration is subjected to ultrafiltration. A dried coating film formed from the residual liquid of the water-dispersed resin composition after repeating this treatment three times is used as a sample. The glass transition temperature is measured using a DSC measuring device using a sample approximately 0.5 mm thick. Regarding the gel content, first, approximately 1 g of a 40 μm thick sample is immersed in 100 ml of toluene at a temperature of 23° C. for 3 days. Thereafter, the sample and toluene are passed through a 200-mesh wire mesh, and the swollen gel on the wire mesh is dried to a constant weight and accurately weighed. The gel content is obtained by dividing the obtained weight by the original weight and expressing it as a percentage. Examples 2 to 6 The disproportionated potassium rosin acid and the chain transfer agent in Example 1 were changed as shown in Table 1, but the same process as in Example 1 was carried out to produce the products shown in Table 1. A water-dispersed resin composition having the pH, polymerization rate, average particle diameter, and gel content of the water-dispersed polymer (a) at the end of polymerization was obtained. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. However, only in Example 4, the pH was not adjusted to 8.0, and after stripping, the solid content was concentrated to 60% and the viscosity was about 10,000 cps. The results are shown in Table 4. Examples 7 to 10 The procedure was exactly the same as in Example 1, except that the monomer mixture and chain transfer agent in Example 1 were changed as shown in Table 2 (0.5 parts of sodium persulfate was used only in Example 7). By the treatment, a water-dispersed resin composition having the pH at the end of polymerization, polymerization rate, average particle diameter, glass transition temperature of water-dispersed polymer (a), and gel content shown in Table 2 was obtained. An adhesive sample of the obtained aqueous dispersion composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured.
The results are shown in Table 4. Example 11 Ammonia was added to the water-dispersed resin composition obtained in Example 8 before steam stripping to adjust the pH.
10, then add an aqueous solution of ammonium rosinate to 15
% and then steam stripping.
The pH of the water-dispersed resin composition after steel stripping was 6.8. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As shown in Table 4, the water-dispersed resin composition containing 20 parts of the higher organic acid exhibited good adhesion properties. Example 12 Caustic soda was further added to the water-dispersed resin composition obtained in Example 1 to adjust the pH to 9.7. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As shown in Table 4, the water-dispersed resin composition containing 25% of the higher organic acid dissolved in the aqueous phase exhibited good adhesive properties. From the results in Table 4, the water-dispersed resin composition of the present invention exhibited clearly superior adhesive properties compared to the conventional water-dispersed adhesives (Comparative Examples 1 and 7) described below. Comparative Example 1 Except for changing the amount of potassium rosin acid in Example 1 to 0, the process was carried out in the same manner as in Example 1, resulting in a pH of 4.4 at the end of polymerization, a polymerization rate of 96%, and an average particle diameter.
A water-dispersed resin composition having a particle diameter of 0.15 μm, a glass transition temperature of minus 65° C. of the water-dispersed polymer (a), and a gel content of 48% was obtained. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As shown in Table 5, the PE adhesion was extremely low when no rosin powder was used. Comparative Example 2 Ammonia was added to the water-dispersed resin composition obtained in Example 8 before steam stripping to adjust the pH.
10, an additional 50 parts of ammonium rosinate was added and then steam stripped. The pH of the water-dispersed resin composition after steam stripping was 7.3. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As shown in Table 5, when 55 parts of the higher organic acid was used, the low temperature tackiness decreased. Comparative Example 3 Caustic soda was further added to the water-dispersed resin composition obtained in Example 1 to adjust the pH to 10.3. In this state, the proportion of rosin acid dissolved in the aqueous phase was 45%. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As shown in Table 5, the proportion of higher organic acids dissolved in the aqueous phase was 45%.
% water-dispersed resin composition had decreased low temperature tack and PE adhesion. Furthermore, when water was dropped onto the surface of the adhesive, it quickly turned white and it was clear that the water resistance was also lowered. Comparative Examples 4 to 6 Polymerizations shown in Table 3 were carried out in the same manner as in Example 1, except that the compositions of the monomer mixture and chain transfer agent in Example 1 were changed as shown in Table 3. A water-dispersed resin composition having a pH at the end, a polymerization rate, an average particle diameter, a glass transition temperature of the water-dispersed polymer (a), and a gel content was obtained. An adhesive sample of the obtained water-dispersed resin composition was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As shown in Table 5, when the glass transition temperature is -10°C or the gel content is 15 or 75%, high temperature cohesion, low temperature adhesion, and/or
PE adhesiveness was insufficient. Comparative Example 7 The same procedure as in Example 8 was carried out except that the amounts of potassium rosin acid and tert-dodecyl mercaptan in Example 8 were changed to 0 and 1 part, respectively, to achieve a pH of 4.3 at the end of polymerization and a polymerization rate of 96 %, an average particle diameter of 0.15 μm, a glass transition temperature of the water-dispersed polymer of minus 65° C., and a gel content of 70%. 70 parts of an aqueous dispersion of rosin glycerin ester having a softening point of 80° C. was added to the obtained water-dispersed polymer, and an adhesive sample was prepared in exactly the same manner as in Example 1, and the adhesive properties were measured. As the results are shown in Table 5, the mixture of the conventional synthetic latex and the aqueous tackifying resin dispersion lacked low-temperature tackiness.

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[Table] * Indicates cohesive failure.

Claims (1)

[Claims] 1 100 parts by weight of a water-dispersed polymer (a) with a gel content of 20 to 70% by weight and a glass transition temperature of -20°C or less and 1
It consists of 0.5 to 30 parts by weight of one or more higher organic acids (b) having at least one carboxyl group in the molecule, and the proportion of (b) dissolved in the aqueous phase is the total amount of (b). 1. A water-dispersed resin composition for an adhesive, characterized in that the content is 35% by dry weight or less.