JP4683828B2 - Method for producing tackifier resin emulsion - Google Patents

Description

  The present invention provides a tackifier resin emulsion capable of producing an aqueous pressure-sensitive adhesive having excellent heat resistance and adhesion.

The tackifier resin emulsion is generally added to a base polymer such as an acrylic polymer emulsion or various latexes for the purpose of improving the adhesive properties, and is used as various adhesives and adhesives.
In recent years, from the viewpoint of environmental protection and occupational health including VOC problems represented by sick house syndrome, tackifier resins are being converted to the above-mentioned aqueous emulsion type instead of the solvent type that has been used conventionally. .
Such an aqueous tackifier resin emulsion is produced by a reversal emulsification method or a high pressure emulsification method. However, in order to cope with non-solventization, for example, Patent Document 1 discloses a continuous high pressure emulsification method that does not use a solvent. Production by is shown.

The above-mentioned water-based emulsion-type adhesives and adhesives have become more sophisticated in performance as their applications expand, but there is a strong demand for satisfying both low temperature adhesiveness and high temperature heat resistance at the same time. Came to be.
For example, Patent Document 2 is obtained by emulsifying rosin or a rosin compound obtained by metallizing a carboxyl group of a rosin derivative having an acid value such as rosin ester for the purpose of improving heat resistance and adhesion to polyolefin. A tackifier resin emulsion is described.
In Patent Document 3, for the purpose of improving tack and adhesive strength at normal temperature and adhesive strength at high temperature,
(1) an acrylic polymer emulsion mainly composed of (meth) acrylic acid ester;
(2) A water-based pressure-sensitive adhesive composition containing a resin acid comprising a resin acid dimer and an emulsion of a tackifier resin having a softening point higher than 150 ° C. and lower than 185 ° C. obtained by reacting a polyhydric alcohol is described. Yes.

Moreover, the following are mentioned as a prior art related to the water-emulsion type tackifier resin or pressure-sensitive adhesive composition for the purpose of imparting heat resistance and the like and including the use of a crosslinking agent.
(1) Patent Document 4
For the purpose of improving heat resistance and water resistance, a curing agent consisting of a mixture of a polyvalent metal salt such as magnesium or barium and an oxazoline ring-containing compound is specified with an acrylic ester aqueous emulsion containing a carboxyl group as the main ingredient A water-dispersed two-part adhesive used in proportions is described. This adhesive describes that the heat resistance is improved by adding a polyvalent metal salt and an oxazoline ring to the functional group in the main component (see paragraph 12).

(2) Patent Document 5
A water-dispersible polymer (A) having a functional group-containing polymer (A1) capable of reacting with an oxazoline group (A1) (for example, a water-dispersible acrylic resin) for the purpose of imparting heat resistance and adhesion A water-based resin composition for use as an adhesive, in which water-soluble polymerizability (B) is used as a cross-linking agent, in which an addition polymerizable oxazoline (a) (paragraph 14) is a monomer composition is described.

(3) Patent Document 6
A combination of a specific amount of rosin or (meth) acrylic acid ester copolymer latex containing polymerized rosin and oxazoline group-containing latex gives heat-resistant adhesiveness, hot water-resistant adhesiveness, etc. (Column 4) Lines 22 to 27), specifically, rosin or polymerized rosin (A) having an acid value of 50 to 150, an oxazoline group-containing copolymer latex (B) having an addition polymerizable oxazoline as a monomer component, and oxazoline An adhesive composition containing a copolymer latex (C) containing a reactive functional group-containing monomer as a constituent component is described.

(4) Patent Document 7
For the purpose of imparting good adhesion even when pressure is applied on a label left under high temperature and high humidity, an adhesive fine particle (A) such as an acrylic copolymer, and acrylic contained as necessary Re-peeling containing a binder (B) such as an aqueous emulsion, a tackifier resin such as a rosin resin or petroleum resin (Claim 6), and a cross-linking agent such as an oxazoline compound (Claims 7 to 8) An adhesive sheet is described. In the Examples, an example using a petroleum resin as a tackifier resin and an oxazoline group-containing polymer as a cross-linking agent is described (paragraphs 105, 109, etc.).

(5) Patent Document 8
Acrylic adhesive emulsion (A) (Claim 2) containing a tackifier resin (paragraph 19) such as rosin resin and petroleum resin is polymerized with styrene, etc. for the purpose of improving the stability of adhesive strength over time. and the copolymer emulsion (B), a glycidyl compound, oxazoline compound, a crosslinking agent such as an aziridine compound (claim 4, paragraphs 29-34) aqueous pressure-sensitive adhesive composition containing a is described.

(6) Patent Document 9
For the purpose of improving the adhesion and adhesion to polyolefin, the ethylenically unsaturated monomer (A) and the tackifier resin (B) (paragraph 20) such as (polymerized) rosin ester and petroleum resin are submerged in water. The emulsion dispersed in is polymerized to produce a resin emulsion (II) , then (meth) acrylic acid alkyl ester (e1), carboxyl group-containing unsaturated monomer (e2), crosslinkable group-containing unsaturated monomer An ethylenically unsaturated monomer (E) (claims 4 to 6) mainly comprising a monomer (e3) is polymerized in the presence of the resin emulsion (II) , or a carbodiimide compound. An emulsion-type pressure-sensitive adhesive composition containing a crosslinking agent (paragraphs 65 to 70) ( Claim 8 ) such as an oxazoline compound or an aziridine compound is disclosed. Example 2 describes an example in which a rosin ester is used as a tackifier resin and an oxazoline-based compound is used as a crosslinking agent.

Japanese Patent Laid-Open No. 11-209477 JP 2000-309771 A JP-A-5-31137 Japanese Patent Laid-Open No. 5-17734 JP-A-5-295275 Japanese Examined Patent Publication No. 7-68501 JP 2000-281989 A JP 2001-207146 A JP 2003-96420 A

In general, the aforementioned low-temperature adhesiveness can be solved by using a tackifier resin having a relatively low softening point, and heat resistance can be solved by using a tackifier resin having a large molecular weight and a high softening point. is there.
However, simply combining the above two methods in order to satisfy both low temperature adhesiveness and high temperature heat resistance at the same time results in relatively poor performance of either one. For example, the molecular weight of the tackifier resin is smaller than that of the base polymer such as the acrylic polymer, and there is a certain limit to improving the heat-resistant retention. To compensate for this, the molecular weight of the tackifier resin is increased. Then, there exists a possibility of causing the fall of adhesive force, the deterioration of compatibility with a base polymer, etc.
The adhesives using the tackifier resins of Patent Documents 2 to 9 are also inevitable to the above-mentioned adverse effects, and are insufficient to satisfy the required low-temperature adhesiveness and heat resistance levels. There are many complicated things.
This invention makes it a technical subject to develop the aqueous | water-based emulsion of the tackifier resin which can manufacture the adhesive agent excellent in the balance of heat-resistant holding power and adhesive force.

The present inventors use a rosin resin that is a tackifier resin in order to ensure low-temperature adhesion, and an aqueous type cross-linking agent that exhibits cross-linking reactivity with respect to the carboxyl group of the rosin resin, such as carbodiimide. In aqueous emulsions containing rosin-based compounds, oxazoline-based compounds, etc., even if rosin-based resins with a low softening point are used, as long as they are a specific type of rosin-based resin having a predetermined acid value, Alternatively, the present invention was completed by paying attention to the fact that the heat-resistant holding power of the pressure-sensitive adhesive is increased by increasing the molecular weight by the reaction between the rosin resin and the crosslinking agent during the production.

The present invention 1 is a method for producing a tackifier resin emulsion in which a mixture of a rosin resin as a tackifier resin and a crosslinking agent having reactivity with a carboxyl group is dispersed in water, wherein the rosin resin is At least one of a polymerized rosin ester and a maleic acid-modified rosin ester, and its acid value is 10 to 130,
A method for producing a tackifier resin emulsion, wherein the crosslinking agent having reactivity to a carboxyl group is at least one compound selected from the group consisting of carbodiimide compounds, oxazoline compounds, and hydrazine compounds. .

The present invention 2 is the tackifier resin emulsion according to the present invention 1, wherein 0.05 to 10 parts by weight of a crosslinking agent is blended with 100 parts by weight of the rosin resin at a ratio in terms of solid content. It is a manufacturing method .

In order to improve the heat resistance retention force, it is necessary to increase the molecular weight of the tackifier resin. On the other hand, this increase in the molecular weight may cause deterioration of adhesiveness and compatibility with the base polymer.
In the present invention, at the time of production or use, a predetermined rosin resin that is a tackifier resin and a predetermined cross-linking agent react with each other to increase the molecular weight by heating at the time of volatilizing moisture, thereby increasing the adhesive force, The heat resistance retention can be improved.
Further, the three-dimensional structure obtained by the crosslinking reaction increases the adhesion to the base material and further improves the adhesive force.
In addition, the above-mentioned patent documents 4 to 9 are those in which a cross-linking agent such as an oxazoline compound and an aqueous resin such as an acrylic acid resin are combined to form an aqueous emulsion, an acrylic resin containing a functional group, a rosin resin, or a petroleum resin. Adhesives such as rosin resins and petroleum resins to acrylic resin emulsions obtained by combining a crosslinking agent mainly with acrylic adhesives containing tackifier resins such as, or by polymerization reaction in multiple stages In the present invention, the rosin resin is used as a cross-linking agent. The pressure-sensitive adhesive can have both low-temperature adhesiveness and heat resistance by a simple treatment of blending and forming an aqueous emulsion.

The present invention is a tackifier resin emulsion in which a mixture of a rosin resin as a tackifier resin and a crosslinking agent capable of reacting with a carboxyl group is dispersed in water.
As the rosin resin, rosins and rosin derivatives can be used alone or in combination.
The rosins are tall rosin, gum rosin, and wood rosin, and are a concept including a disproportionated rosin, a polymerized rosin, a hydrogenated rosin, or a purified product of these rosins.
The rosin derivative is obtained by chemically modifying rosins, and examples thereof include rosin esters, unsaturated carboxylic acid-modified rosins, and unsaturated carboxylic acid-modified rosin esters.

The said rosin ester means what manufactured the said rosin and polyhydric alcohol by the well-known esterification method. In this case, the modification ratio of rosins and polyhydric alcohol is suitably about COOH / OH = 1 / (0.2 to 2.0) in terms of the hydroxyl group equivalent ratio of alcohol to the carboxyl group equivalent of rosin.
Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, dihydric alcohols such as 1,3-butanediol and 1,6-hexanediol, glycerin, trimethylolpropane, Trivalent alcohols such as trimethylolethane and triethylolethane, tetravalent alcohols such as pentaerythritol and diglycerin, hexavalent alcohols such as dipentaerythritol, or triethanolamine, tripropanolamine, triisopropanolamine, N-isobutyl Examples include amino alcohols such as diethanolamine and N-normal butyl diethanolamine.

The unsaturated carboxylic acid-modified rosin is obtained by reacting the rosin with an α, β-unsaturated carboxylic acid by a known method. In this case, the modification amount of the α, β-unsaturated carboxylic acids is preferably about 20 parts by weight or less with respect to 100 parts by weight of the rosins.
Examples of the α, β-unsaturated carboxylic acids include fumaric acid, (anhydrous) maleic acid, itaconic acid, (anhydrous) citraconic acid, acrylic acid, and methacrylic acid.

The unsaturated carboxylic acid-modified rosin esters can be obtained by reacting the rosins with α, β-unsaturated carboxylic acids and polyhydric alcohols sequentially or simultaneously.
The addition reaction between rosins and α, β-unsaturated carboxylic acids and the esterification reaction with polyhydric alcohol are as described above.

The rosin resin used in the present invention is selected from polymerized rosin esters and maleic acid-modified rosin esters among the rosin resins described above, and these are used singly or in combination.
The acid value of these rosin resins is 10 to 130, and if the acid value is lower than the appropriate range, the reaction with the crosslinking agent is not promoted, the high molecular weight is insufficient, and the heat resistance holding power may be insufficient. If the acid value exceeds the appropriate range, the cohesive force may increase due to excessive crosslinking, and the adhesive performance may be reduced .

The crosslinking agent having reactivity to the carboxyl group used in the present invention is at least one compound selected from the group consisting of carbodiimide compounds, oxazoline compounds, and hydrazine compounds , with oxazoline compounds being particularly preferred.
The carbodiimide compound may be any compound having at least two carbodiimide groups, and commercially available products include carbodilite (manufactured by Nisshinbo Industries, Inc.).
The oxazoline-based compound may be any compound having at least two oxazoline groups. Specifically, 2-methyl-2-oxazoline, 2-ethyl-2-oxazoline, 2-isopropyl-2-oxazoline, 2-n-propyl-2-oxazoline, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2- It is a polymer such as oxazoline, and commercially available products include Epocros (manufactured by Nippon Shokubai Co., Ltd.) .
The hydrazine-based compound may be any compound having at least two hydrazine groups. Specifically, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, Examples thereof include maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide and the like.

As described above, the crosslinking agent composed of a carbodiimide compound, an oxazoline compound, and a hydrazine compound can be used alone or in combination, and different compounds may be used in combination.
As shown in the present invention 2 , the cross-linking agent is blended in an amount of 0.05 to 10 parts by weight with respect to 100 parts by weight of the rosin resin at a solid content conversion ratio.
If the amount is less than 0.05 parts by weight, the high molecular weight is hindered due to insufficient crosslinking reaction with the rosin resin, and the heat resistance is insufficient. If the amount exceeds 10 parts by weight, the adhesive is excessively cured (cohesive force becomes too high). In addition to being worse, the cost is also high.

The tackifier resin emulsion of the present invention is produced by dispersing a mixture of the above tackifier resin and a crosslinking agent in water using an emulsifier.
The emulsifier is not particularly limited, and various emulsifiers such as anionic, nonionic, and synthetic polymer can be used alone or in combination. The amount used is suitably 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the total solid content of the tackifier resin and the crosslinking agent.

Examples of the anionic emulsifier include organic sulfonic acids, alkali metal salts of sulfuric esters, ammonium salts, and the like, and specifically include the following (1) to (6).
(1) Alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate.
(2) Alkyl (or alkenyl) sulfate esters such as sodium lauryl sulfate and oleyl sulfate
(3) Polyoxyethylene alkyl (or alkenyl) ether sulfates such as sodium polyoxyethylene lauryl ether sulfate and sodium polyoxyethylene oleyl ether sulfate.
(4) Polyoxyethylene alkylaryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate and sodium polyoxyethylene styryl phenyl ether sulfate.
(5) Alkylsulfosuccinic acid ester salts such as sodium monooctylsulfosuccinate, sodium dioctylsulfosuccinate, disodium polyoxyethylene laurylsulfosuccinate, and derivatives thereof.
(6) Alkyl diaryl ether disulfonates such as sodium alkyl diphenyl ether disulfonate and derivatives thereof.

Examples of the nonionic emulsifier include the following (1) to (7).
(1) Polyoxyethylene alkyl (or alkenyl) ethers such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether.
(2) Polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonyl phenyl ether and polyoxyethylene styryl phenyl ether.
(3) Higher sorbitan fatty acid esters such as sorbitan monolaurate and sorbitan trioleate.
(4) Polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate.
(5) Polyoxyethylene higher fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monooleate.
(6) Glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride.
(7) Polyoxyethylene / polyoxypropylene block copolymer.

  The above synthetic polymer-based emulsifiers are styrene, α-methylstyrene, vinyl toluene, (meth) acrylic acid, maleic acid, (meth) acrylic acid esters, acrylic amide, vinyl acetate, styrene sulfonic acid, isoprene sulfonic acid, Polymers obtained by polymerizing two or more polymerizable monomers such as vinyl sulfonic acid, allyl sulfonic acid, and 2- (meth) acrylamide-2-methylpropane sulfonic acid are converted into alkalis such as sodium hydroxide, potassium hydroxide, and ammonia. It is a water-dispersible polymer which is salt-formed with water and dispersed or solubilized in water. In addition to the above monomers, polymerizable monomers can be used without limitation, and the polymerization method is not particularly limited.

The method for producing the tackifier resin emulsion is not particularly limited, and can be produced by a solvent-type emulsification method, a solvent-free emulsification method, a phase inversion emulsification method, or other known emulsification methods, but VOC problems such as sick house syndrome From the viewpoints of environmental protection, occupational health, and safety including the solvent-free emulsification method is preferred.
The solvent-type emulsification method may be carried out by using a tackifier resin as a chlorine-based hydrocarbon solvent such as methylene chloride, an aromatic solvent such as toluene or xylene, a ketone-based solvent such as methyl ketone or methyl isobutyl ketone, or a soluble solvent. After preparing an aqueous emulsion of coarse particles by pre-mixing emulsified water in which an emulsifier and water are mixed and dissolved in an organic solvent such as, various mixers, colloid mills, high pressure emulsifiers, high pressure discharge emulsifiers, high In this method, after finely emulsifying using a shearing type emulsifying disperser or the like, the organic solvent is removed while heating under normal pressure or reduced pressure.
In the above solventless emulsification method, a tackifier resin melted under normal pressure or under pressure and emulsified water are premixed to prepare an aqueous emulsion of coarse particles, and then finely emulsified in the same manner using various emulsifying dispersers. Is the method.
In the phase inversion emulsification method, after the tackifier resin is heated and melted at normal pressure or under pressure, the emulsified water is gradually added while stirring to form a water-in-oil emulsion, and then the oil-in-water type is used. This is a method for reversing the phase of the emulsion, and any of the solvent method and the solventless method can be used.

In the tackifier resin emulsion of the present invention, various base polymers such as aqueous acrylic polymer, natural rubber latex, synthetic rubber latex such as SBR and CR, or other aqueous synthetic polymer emulsion are blended, An aqueous sticky / adhesive composition is produced.
The base polymer is not particularly limited as long as it is a water-based polymer used for water-based adhesive / adhesive applications.
The blending amount of the tackifier resin emulsion with respect to the base polymer is appropriately determined according to the use.
The tackifier resin emulsion and aqueous adhesive / adhesive composition of the present invention include an antifoaming agent, a thickening agent, a filler, an antioxidant, a water-resistant agent, a film-forming aid and the like as necessary. These various additives may be slightly added.

Hereinafter, examples of the tackifier resin emulsion of the present invention, examples of producing an acrylic polymer emulsion as a base polymer, examples of producing an aqueous adhesive containing the tackifier resin emulsion and the acrylic polymer emulsion, and The adhesion performance evaluation test examples of the water-based pressure-sensitive adhesive will be sequentially described. Further, “parts” and “%” in Examples, Production Examples, and Test Examples are based on weight unless otherwise specified.
It should be noted that the present invention is not limited to the following examples and test examples, and can be arbitrarily modified within the scope of the technical idea of the present invention.

<< Example of tackifier resin emulsion >>
Examples 1 to 3 are examples in which an oxazoline-based crosslinking agent was blended in various solid content conversion ratios into a polymerized rosin ester or a maleic acid-modified rosin ester having different acid values and softening points.
In Comparative Examples 1 to 3, the rosin resin corresponding to Examples 1 to 3 is formed into an aqueous emulsion without adding a crosslinking agent.
(1) Example 1
100 parts of a rosin resin emulsion (solid content 50%) using a polymerized rosin ester having an acid value of 10 and a softening point of 97 ° C., 2 parts (solid conversion) of an emulsion type oxazoline-based crosslinking agent (solid content 40%) Addition to produce a tackifier resin emulsion.

(2) Example 2
For 100 parts of a rosin resin emulsion (solid content 50%) using a polymerized rosin ester having an acid value of 19 and a softening point of 103 ° C., 1 part (solid conversion) of an emulsion type oxazoline-based cross-linking agent (solid content 40%) ) To produce a tackifier resin emulsion.

(3) Example 3
0.5 parts of emulsion type oxazoline-based cross-linking agent (solid content 40%) to 100 parts of rosin resin emulsion (solid content 50%) using maleic acid-modified rosin ester having an acid value of 30 and a softening point of 135 ° C (Solid conversion) Added to produce a tackifier resin emulsion.

(4) Comparative Example 1
A crosslinker was not added to a rosin resin emulsion (solid content 50%) using a polymerized rosin ester having an acid value of 10 and a softening point of 97 ° C., and a tackifier resin emulsion was used as it was.

(5) Comparative example 2
A crosslinker was not added to a rosin resin emulsion (solid content 50%) using a polymerized rosin ester having an acid value of 19 and a softening point of 103 ° C., and a tackifier resin emulsion was used as it was.

(6) Comparative Example 3
A tackifier resin emulsion was used as it was without adding a crosslinking agent to a rosin resin emulsion (solid content 50%) using a maleic acid-modified rosin ester having an acid value of 30 and a softening point of 135 ° C.

Then, the water-based acrylic adhesive was manufactured by mix | blending a base polymer with each tackifier resin emulsion of the said Examples 1-3 and Comparative Examples 1-3.
<< Production Example of Aqueous Emulsion Type Acrylic Adhesive >>
First, an acrylic polymer emulsion as a base polymer was produced as follows.
That is, 60.0 parts of ion-exchanged water and 0.1 part of a reducing agent (sodium bisulfite) were dissolved in a reactor equipped with a stirrer, a cooler, a thermometer, and a nitrogen introduction tube under a nitrogen gas stream. An aqueous solution (a) was obtained. In addition, 1.5 parts of polyethylene glycol nonylphenyl ether and 1.5 parts of polyethylene glycol oleyl ether ammonium sulfonate are dissolved in 34.5 parts of ion-exchanged water, and 97.0 parts of n-butyl acrylate and 3 parts of methacrylic acid are dissolved therein. 0.0 part and 0.5 part of catalyst (ammonium persulfate) were added and pre-emulsified with a homomixer to obtain dispersion (b).
The aqueous solution (a) was kept at 82 ° C., and the dispersion (b) was dropped into the solution over 4 hours. After the dropwise addition of the entire amount of the dispersion (b), the reaction was carried out at 82 ° C. for 1 hour, and 2.0 parts of ion-exchanged water, 0.1 part of a reducing agent (sodium bisulfite) and 0. What dissolved 1 part was added.
The reaction was further completed for 1 hour, cooled, and filtered through a 150 mesh wire mesh to obtain an acrylic polymer emulsion having a solid content of 49.5%.
Next, with respect to 100 parts of the acrylic polymer emulsion (in terms of solid content), each of the tackifier resin emulsions of Examples 1 to 3 and Comparative Examples 1 to 3 is added at a ratio of 10 parts (in terms of solid content). Thus, an aqueous emulsion type acrylic pressure-sensitive adhesive was produced.

<< Example of adhesive performance evaluation test for aqueous emulsion adhesives >>
Therefore, aqueous pressure-sensitive adhesives using the tackifier resin emulsions of Examples 1 to 3 and Comparative Examples 1 to 3, and those using only acrylic polymer emulsions, and oxazoline-based acrylic polymer emulsions. About what added 0.2 part of crosslinking agents (solid content 40%) in solid conversion, after coating on PET film with a thickness of 25 μm under the condition that the coating thickness after drying becomes 30 μm, at 120 ° C. A pressure-sensitive adhesive sheet was prepared by drying for 5 minutes and subjected to the following various performance evaluation tests.

(1) Tack According to the J. Dow method described in JIS-Z0237, 1/32 (steel ball No. 1) to 32/32 (steel ball No. 32) inch steel balls are rolled on the adhesive sheet. The number of the largest steel ball that stops on the sheet was measured under the conditions of an inclination of 30 degrees and a measurement temperature of 23 ° C. Therefore, in this test, the larger the ball number, the better the tack performance.

(2) Holding power The holding power test was performed using the deviation of the cohesive force test as a criterion.
That is, based on JIS-Z0237, using a stainless steel plate (SUS304 polished with 280 polishing paper and surface-treated), the 25 × 25 mm pressure-sensitive adhesive sheet was attached thereto, and the direction of gravity was While the load of 1 kg was applied, the deviation width (mm) after applying the load at a temperature of 40 ° C. for 1 hour was measured.

(3) Adhesive strength Based on JIS-Z0237, a stainless steel plate (SUS304 polished with 280 polishing paper) and a polyethylene plate were used as the adherend, and the 25 mm wide adhesive sheet was applied to this. After peeling, the peel strength when 20 minutes later was peeled off at a speed of 300 mm / min in the direction of 180 degrees was measured.

(4) Constant load peel test Using a stainless steel plate (SUS304 polished with 280 polishing paper and surface-treated) as an adherend, the above adhesive sheet having a width of 25 mm and a length of 50 mm was attached to the adherend. A weight of 80 g load was fixed to one side of the sheet, placed horizontally so that the adhesive sheet was on the lower side, and allowed to stand in a form that suspended the weight.
Next, the degree of peeling (deviation width) of the pressure-sensitive adhesive sheet after 1 hour at 50 ° C., or the time until the weight falls was recorded.

(5) Softening temperature of adhesive tape A stainless steel plate (SUS304 polished with 280 polishing paper and surface-treated) was used as the adherend, and the above-mentioned adhesive sheet of 25 × 25 mm was attached to this, and in the direction of gravity. The sample was allowed to stand at an ambient temperature of 38 ° C. for 30 minutes with a 500 g load applied, and then the ambient temperature was increased at a rate of 3 ° C./5 minutes to measure the ambient temperature when the adhesive tape peeled off from the adherend. did.
In this test, the higher the measured temperature, the higher the heat resistance of the adhesive.

FIG. 1 shows the test results. In addition, Ac in a figure shows an acrylic polymer emulsion. Examples 1 to 3 in which a crosslinking agent was blended in a rosin resin and Comparative Examples 1 to 3 in which a crosslinking agent was not used were prepared using the same kind of rosin resin (Example n and Comparative Example n (n = 1, 2). 3)), the example is superior in both adhesive strength and holding strength against polyethylene, and the embodiment can maintain a practical level with respect to tack and stainless steel as well, and a constant load at 50 ° C. It was confirmed that the examples showed a significant advantage over the comparative examples in terms of peelability and the softening temperature of the adhesive tape.
In particular, in the constant load peel test, the deviation width was measured in the example, whereas in the comparative example, the pressure-sensitive adhesive sheet itself with the weight was dropped, so the drop time of the weight was not measured. Did not get. Even in the softening temperature test, the adhesive tapes of Examples 2 to 3 did not peel off even under heating conditions of 150 ° C. or higher.

Therefore, if a tackifier resin emulsion in which a crosslinking agent is blended with a rosin resin is used, the adhesive can have good adhesion at low temperature and heat resistance at high temperature, and the type of rosin resin used and It has been clarified that even if the blending ratio of the rosin resin and the crosslinking agent is changed, the low-temperature adhesiveness and the heat resistance can be combined.
If only the base polymer is used, the adhesive properties other than tack are greatly inferior from the practical level, and even if only the base polymer and the crosslinking agent are used without using the rosin resin, the base polymer alone The result was far from the practical level, with only a slight improvement in adhesive properties.

It is a graph which shows the result of the adhesive physical-property evaluation test of the water-based adhesive produced using each tackifier resin emulsion, such as Examples 1-3 and Comparative Examples 1-3.

Claims (2)

A method for producing a tackifier resin emulsion in which a mixture of a rosin resin as a tackifier resin and a crosslinking agent having reactivity to a carboxyl group is dispersed in water,
The rosin resin is at least one of a polymerized rosin ester and a maleic acid-modified rosin ester, and its acid value is 10 to 130,
A method for producing a tackifier resin emulsion, wherein the crosslinking agent having reactivity with a carboxyl group is at least one compound selected from the group consisting of carbodiimide compounds, oxazoline compounds, and hydrazine compounds. The method for producing a tackifier resin emulsion according to claim 1 , wherein 0.05 to 10 parts by weight of a crosslinking agent is blended with 100 parts by weight of the rosin resin at a ratio in terms of solid content.

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