JP2000313867A - Aqueous pressure-sensitive adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous pressure-sensitive adhesive composition which shows an excellent balance between the adhesion performance such as an adhesion against non-polar adherents such as olefins, or the like, a maintenance strength, a curved surface adhesion, or the like, and the water resistance. SOLUTION: This composition comprises a polymer emulsion obtained by polymerizing a monomer emulsion which is sequentially introduced in multiple steps or a single step into a seed emulsion in the presence of a polymerization initiator. Here, as the seed emulsion, 70 wt.% or more long-chain alkyl (meth) acrylate wherein the carbon number of the alkyl group is from 9 to 14, is used against the total amount of its use. Furthermore, the monomer emulsion mainly comprises a short-chain alkyl (meth)acrylate wherein the carbon number of the alkyl group is 8 or smaller, and the remaining portion comprises a long- chain alkyl (meth)acrylate. In each step of the multiple or single step sequential introduction of the monomer emulsion, 10 wt.% or less long-chain alkyl (meth) acrylate based on the total amount of its use is used, and the monomer emulsion contains from 2 to 80 wt.% long-chain alkyl (meth)acrylate based the total monomer composition. An adhesive product is obtained by using the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based pressure-sensitive adhesive which has good adhesion to non-polar adherends such as olefins and the like, and excellent balance of adhesion performance such as holding power and water whitening resistance. The present invention relates to an agent composition, a method for producing the same, and an adhesive product obtained by using the same.

[0002]

2. Description of the Related Art From the viewpoints of improving the global environment and working environment and effective use of resources, conversion to an emulsion type adhesive has been studied as an alternative to a solvent type adhesive. Conventionally, butyl acrylate or 2
Emulsion-type pressure-sensitive adhesives have been produced by emulsion polymerization using a short-chain alkyl (meth) acrylate such as ethylhexyl acrylate. These are tacky, stainless steel, high adhesion to polar adherends such as polyethylene terephthalate, but low adhesion to non-polar adherends such as polyethylene and polypropylene, and holding power,
It has the drawback of poor adhesion to curved surfaces. In order to improve these, it has been attempted to add a long-chain alkyl (meth) acrylate to a short-chain alkyl (meth) acrylate, to increase the wettability to a non-polar adherend and to improve the adhesion, In addition, by increasing the glass transition temperature, the holding power and the curved surface adhesion are improved. On the other hand, as a method for preparing these short-chain alkyl (meth) acrylates, there is a multi-stage polymerization method in which a seed emulsion is prepared in advance and a monomer is added dropwise to the seed emulsion because the emulsion particle size is easily controlled. When a long-chain alkyl (meth) acrylate is added in order to solve the above-mentioned drawbacks by this multi-stage polymerization method, a long-chain alkyl (meth) acrylate is added to a dropping monomer disclosed in JP-A-53-84092. Is added in a large amount such as 60% or more and the multi-stage polymerization is performed, the long-chain alkyl (meth) acrylate in the dropped monomer has a slower diffusion supply to the seed emulsion particles than the short-chain alkyl (meth) acrylate. As a result, oil droplets of the long-chain alkyl (meth) acrylate alone are formed, which has an adverse effect on the adhesive performance, and causes long-chain alkyl (meth) acrylate to have a holding force, a curved surface adhesiveness, and the like.
The effect of adding acrylate is not sufficiently exhibited.

It is an object of the present invention to provide an adhesive property such as adhesiveness to nonpolar adherends such as olefins, holding power, and adhesion to curved surfaces.
An object of the present invention is to provide a water-based pressure-sensitive adhesive composition having an excellent balance with water resistance.

[0004]

SUMMARY OF THE INVENTION The present invention comprises a polymer emulsion obtained by successively supplying a monomer emulsion to a seed emulsion in the presence of a polymerization initiator in multiple stages or in one stage to carry out polymerization. In the emulsion, at least 70% by weight of the total amount of the long-chain alkyl (meth) acrylate having 9 to 14 carbon atoms in the alkyl group (hereinafter simply referred to as long-chain alkyl (meth) acrylate) is used. And a short-chain alkyl (meth) acrylate having an alkyl group of 8 or less carbon atoms as a main component, and a balance of less than 30% by weight of a long-chain alkyl (meth) acrylate in a multi-stage or single-stage amount of 10%. % Or less, and the long-chain alkyl (meth) acrylate is used in the total monomer composition (the sum of the seed and the monomer supplied sequentially in all stages). Composition, for the same below) from 2 to 80
Provided are a water-based pressure-sensitive adhesive composition containing 0.1% by weight, a method for producing the same, and a pressure-sensitive adhesive product obtained by using the same.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The long-chain alkyl (meth) acrylate used in the seed emulsion of the present invention has a linear or branched alkyl group having 9 to 14 carbon atoms.
Nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, isododecyl (meth) acrylate, tridecyl (meth) acrylate, isotridecyl (meth) acrylate, and the like. Can be The use of the long-chain alkyl (meth) acrylate improves the adhesive strength to a non-polar adherend, the holding power, and the curved surface adhesion. The content of these long-chain alkyl (meth) acrylates is 2 to 80% by weight based on the total monomer composition, from the viewpoint of the balance of the adhesive performance.
It is preferably 3 to 60% by weight, more preferably 4 to 40% by weight, particularly preferably 5 to 20% by weight. If the amount of the long-chain acrylic (meth) acrylate is too large, defects such as inferior tackiness occur, and if it is too small, the effect of addition is not seen.

The amount of the monomer used as the seed emulsion is preferably from 2.5 to 80% by weight, more preferably from 5 to 60% by weight, more preferably from 10 to 50% by weight, based on the particle size control. In addition, since the water-insoluble long-chain alkyl (meth) acrylate particles are contained in the seed emulsion, the emulsion particles can be easily controlled. When the water-insoluble long-chain alkyl (meth) acrylate is added to the monomer emulsion, the diffusion and supply to the seed emulsion particles is slower than the short-chain alkyl (meth) acrylate. The polymer oil droplets are formed alone, so that a uniform composition distribution cannot be obtained and the particle size distribution becomes non-uniform. Therefore,
As a result, the balance of adhesion performance such as holding power and curved surface adhesion is poor, and the effect of adding the long-chain alkyl (meth) acrylate is not sufficiently exhibited. Therefore, it is important that the sequentially supplied monomer emulsion is mainly composed of a short-chain alkyl (meth) acrylate having an alkyl group of 8 or less carbon atoms. 10% by weight or less, preferably 5% by weight or less,
It is particularly preferable not to use it. In the seed emulsion, any monomer containing a short-chain acrylic (meth) acrylate may be used as long as the desired adhesive performance is not deteriorated, and additives other than the monomer such as a plasticizer and a tackifier may be used. And a chain transfer agent such as dodecyl mercaptan for adjusting the molecular weight.

[0007] The short-chain alkyl (meth) acrylate used as the main component of the sequentially supplied monomer in the present invention has an alkyl group having 1 to 8 carbon atoms.
Examples include acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Also,
Other monomers such as styrene and additives other than monomers can be used within a range that does not deteriorate the intended adhesive performance, and a chain transfer agent such as dodecyl mercaptan may be used to adjust the molecular weight. it can.

It is preferable to use an α, β-unsaturated monocarboxylic acid or dicarboxylic acid in the seed emulsion and / or the sequentially supplied monomer emulsion of the present invention.
Examples of the α, β-unsaturated monocarboxylic acid include acrylic acid, methacrylic acid and crotonic acid, and examples of the α, β-unsaturated dicarboxylic acid include maleic acid, fumaric acid and citraconic acid. Their content is preferably 0.5% by weight or more based on the total monomer composition from the viewpoint of improving the adhesion to the polar adherend and the mechanical stability, and from the viewpoint of water resistance.
5.0% by weight or less is preferred. More preferably 0.5 to 3.0
% By weight, particularly preferably 0.5 to 2.0% by weight. Further, from the viewpoint of improving the adhesiveness to the polar adherend and the mechanical stability, the monomer monomer is preferably contained in the monomer monomer emulsion of 0.5% by weight or more, especially 0.5 to 5% by weight, based on the total monomer composition. Is more preferred.

[0009] Further, by the copolymerization of methyl methacrylate, it is possible to further improve the holding power, the curved surface adhesion, and the adhesion to PET (polyethylene terephthalate plate). From the above viewpoint, the content of this methyl methacrylate is preferably 5% by weight or more based on the total monomer composition, and the seed and the successively supplied monomers in all stages are always contained in an amount of 1.0% by weight or more based on the total monomer composition. Is preferred.

The polymerization initiator includes persulfates such as potassium persulfate and ammonium persulfate, organic peroxides such as benzoyl peroxide and lauroyl peroxide, and 2,2'-azobis (isobutyronitrile); 2,2′-azobis (2
Azo-based polymerization initiators such as -aminomethylbutyronitrile) and 4,4'-azobis (4-cyanovaleric acid). Further, a peroxide-based polymerization initiator and L
-Redox initiators such as combinations of ascorbic acid or iron ions, persulfates and sulfites, combinations of hydrogen peroxide and iron ions, etc. can also be used.

In particular, by using a redox-based initiator and an azo-based initiator in combination, or by using a redox-based initiator and an organic peroxide-based initiator in combination, the adhesive strength and holding power, the curved surface adhesiveness, and the like are further improved. It is more preferable because the balance of adhesive performance such as water resistance becomes good. The amount of polymerization initiator is based on the total monomer composition
It is preferably 0.01 to 1% by weight, more preferably 0.05 to 0.5%.
%, Particularly preferably from 0.1 to 0.5% by weight. The polymerization initiator can be added to both the seed emulsion composition and the sequentially supplied monomer emulsion composition, but is preferably added to the seed emulsion composition from the viewpoint of controlling the particle size of the emulsion particles.

In the polymerization of the present invention, a cationic, anionic or nonionic emulsifier can be used. In consideration of water resistance, an emulsifier having a radical polymerizable double bond in the molecule is preferable. WO97 / 07174 No. 13 ~
Those described on page 15 can be used. Further, an emulsifier having no radical polymerizability or a water-soluble polymer type emulsifier can be used in combination with the radical polymerizable emulsifier. The amount of the emulsifier used is preferably 0.5% by weight or more, more preferably 1.0% by weight or more based on the total amount of monomers, from the viewpoint of polymerization stability and mechanical stability. On the other hand, from the viewpoint of improving the water resistance, the amount is preferably 5.0% by weight or less, more preferably 4.0% by weight or less, particularly preferably 2.5% by weight or less based on the total amount of the monomers.

In the present invention, when preparing a seed emulsion, it contains a hardly water-soluble long-chain alkyl (meth) acrylate, and is thus emulsified and dispersed in a monomer or emulsifier aqueous solution to be used in advance to form monomer droplets. The method of forming and polymerizing is preferred. By using this method, the particle size control is further facilitated. The average particle size of the seed emulsion is preferably 5 μm or less, more preferably 3 μm or less, further preferably 1 μm or less, particularly preferably 0.5 μm or less. In general, the smaller the particle size, the more advantageous the diffusion of the monomer sequentially fed into the seed emulsion. Therefore, the smaller the average particle size of the seed emulsion particles, the better the operability of the emulsion is. Any type of emulsifying machine can be used as long as the average particle size of the monomer emulsion can be reduced to 5 μm or less. For example, an ultrasonic homogenizer (Nippon Seiki Seisakusho), a high-pressure homogenizer (manufactured by Izumi Food Machinery) and the like can be used.
In addition, the monomer emulsion which is successively supplied can also be emulsified by the above emulsification method, and the average particle size is preferably 5 μm or less, more preferably 3 μm or less.

The polymerization step in the present invention is performed by dropping a monomer emulsion in the presence of a polymerization initiator using the seed emulsion as a site for polymerization. The polymerization temperature varies depending on the monomer composition and the type of polymerization initiator, but is 40 to 80.
C is preferred. The polymerization time also depends on the composition of the monomer, the type of polymerization initiator and the polymerization temperature, but is preferably 4 to 8 hours.

The dropping of the monomer emulsion may be carried out in one step, or in two steps, three steps, or more steps. Further, the amount of the dropping emulsion, the dropping speed, and the timing of dropping can be appropriately changed depending on the monomer composition used, the type and amount of the initiator, and the like.

The particle size of the polymer emulsion obtained after the polymerization has a great effect on water resistance, especially water whitening resistance, and the smaller the particle size, the better the film-forming properties.
m or less, more preferably 0.8 μm or less, still more preferably
0.5 μm or less.

The water-based pressure-sensitive adhesive composition of the present invention comprising the polymer emulsion thus obtained has high adhesive strength to non-polar adherends such as olefins, and excellent holding power and curved surface adhesiveness. Can be compatible. If necessary, a wetting agent, a stabilizer,
Additives such as a tackifier, a thickener and an antifoaming agent can be appropriately blended and used.

Examples of the wetting agent include general alkyl poly (oxyalkylene) -based nonionic surfactants, alkyl sulfate ester salts, alkyl phosphate ester salts, alkyl poly (oxyalkylene) sulfate ester, and alkyl poly ( Anionic surfactants such as (oxyalkylene) phosphoric acid ester salts and the like, which can improve the wettability without greatly deteriorating the adhesive performance, are mentioned. Examples of the thickener include acrylic acid-based alkali thickeners, cellulose-based and urethane-based thickeners.

The pressure-sensitive adhesive product of the present invention is produced by applying the above-mentioned water-based pressure-sensitive adhesive composition to a base material and drying it. Examples of the adhesive product include an adhesive label, an adhesive sheet, an adhesive tape, and a surface protection film. The pressure-sensitive adhesive product of the present invention is excellent in adhesive strength, holding power, curved surface adhesion, water resistance, and extremely excellent in the balance of adhesive performance.

[0020]

EXAMPLES In the following examples,% is% by weight unless otherwise specified. The particle size is an average particle size measured using a particle size distribution analyzer manufactured by HORIBA (LA-910, refractive index 1.20).

Example 1 In a separable container, 31.8 g of lauryl methacrylate, 14.1 g of methyl methacrylate, 94.1 g of 2-ethylhexyl acrylate, 1.41 g of styrene, 0.033 g of n-dodecyl mercaptan, and 2,2'-azobis (2-methylbutyro) Nitrile) 1.27 g, t-butyl hydroperoxide 0.
21 g of the monomer solution was mixed and stirred, and the monomer solution was mixed with a reactive emulsifier, Latemul S-180 (50% aqueous solution / manufactured by Kao Corporation, hereinafter S-18).
7.06 g) was dispersed in an aqueous solution of 179 g of water. The suspension was forcibly emulsified and dispersed for 4 minutes with an ultrasonic homogenizer (Nippon Seiki Seisakusho, the same hereinafter) to prepare a seed emulsion having a particle size of 0.36 μm. While introducing nitrogen into the separable container for 10 minutes,
The emulsion was stirred, and 1.28 g of an aqueous solution in which 0.5 g of L-ascorbic acid as a redox initiator was dissolved in 10 g of water.
Was added. Thereafter, the inside of the system was adjusted so as to increase the temperature by 5 ° C. in 15 minutes. After the temperature was increased to 75 ° C., the temperature was kept constant.

When the temperature in the system during the temperature rise reached 50 ° C., the first-stage emulsion was dropped into the system over 1 hour. The first emulsion is acrylic acid 2.12
g, 14.1 g of methyl methacrylate, 123.8 g of 2-ethylhexyl acrylate, 1.41 g of styrene, and 0.033 g of n-dodecyl mercaptan, 2.82 g of S-180
Was dropped and dispersed in an aqueous solution in which 87.2 g of water was dissolved, and forcibly emulsified and dispersed by an ultrasonic homogenizer for 6 minutes (particle size: 3 μm). After the first-stage emulsion was dropped, the second-stage emulsion was further dropped over 1 hour. The second-stage emulsion was prepared by adding a monomer solution of 4.24 g of acrylic acid, 14.1 g of methyl methacrylate, 121.7 g of 2-ethylhexyl acrylate, 1.41 g of styrene, and 0.033 g of n-dodecyl mercaptan to S-180.
2.82 g was dropped and dispersed in an aqueous solution in which 87.2 g of water was dissolved, and forcibly emulsified and dispersed with an ultrasonic homogenizer for 4 minutes (particle size: 3 μm). Then 5.5 more
Stirring was performed at 75 ° C. for an hour. Then cool, 25
The pH was adjusted to 7.0 to 7.5 by neutralization with an aqueous ammonia solution. The particle size of the emulsion after polymerization was 0.16 μm, and the solid content was 52.5%. In addition, the viscosity of the emulsion was low and was at a level that would not hinder stirring. Table 1 shows the emulsion composition ratio and particle size.

Next, superester E-86 having a concentration of 50% was added to the polymer emulsion as a tackifier.
5 (manufactured by Arakawa Industry Chemical Co., Ltd.) was added at 5% to the solid content of the emulsion. Furthermore, as a thickener, an aqueous solution of Primal TT-935 (manufactured by Rohm & Haas) having a concentration of 10% was mixed with a B-type viscometer (Tokyo Keiki, No. 4 rotor, rotation speed 60 rpm,
Emulsion viscosity measured at 25 ° C) is 2000-3000
mP · s was added to prepare a water-based pressure-sensitive adhesive composition. The mechanical stability of the obtained water-based pressure-sensitive adhesive composition was measured by the following method. Further, a coated film was prepared by the following method, and the adhesive performance was measured (based on JIS Z0237). Table 2 shows the results.

(1) Measurement of Mechanical Stability Using a Maron mechanical stability tester (manufactured by Riken Seiki Seisakusho Co., Ltd.), 10 kg of water-based pressure-sensitive adhesive composition
The test was carried out under a load of 1000 rpm for 5 minutes, and the results were shown by weight% of agglomerates with respect to solid content of the water-based pressure-sensitive adhesive composition. The lower the numerical value of this weight%, the better the mechanical stability.

(2) Preparation of Coated Film Using an applicator on the release film, the adhesive composition was applied so that the coated thickness after drying was 20 to 24 μm, 25 cm in length and 8 cm in width. The coated film was prepared by drying with hot air and stacking the base films. As a substrate film, surface corona treated OPP (biaxially oriented polypropylene film, thickness 50 μm, width 150 mm, length 350 mm), or surface corona treated PET (polyethylene terephthalate film, length 350 mm, width 150 mm, thickness 50 μm) It was used. The release film used was 38 μm of PET ID-8 [San Kaken Co., Ltd.]. Drying was carried out in a hot air dryer (Perfect Oven, manufactured by Tabai) at 110 ° C./30 sec. The finished coated film is 23 ℃ / 65% RH
After aging for 3 days under, it was used for the following measurements.

(3) Evaluation of Adhesive Performance Curved Adhesiveness A coating film (2.2 cm × 3 cm) using PET having been subjected to surface corona treatment as a base material is coated on a high-density polyethylene rod of 10 mmφ by 70% in the circumferential direction. 40 ℃ / 40 after attachment
It was left for 24 hours under% RH. The evaluation was carried out by observing the adhesive performance of the film, and indicated by five levels shown in FIG. In FIG. 1, 1 is a coated film, and 2 is a high-density polyethylene rod.

Permanent Adhesive Strength Untreated surface adherend (high density polyethylene plate (PE), polyethylene terephthalate plate (P
ET) and stainless steel plate (SUS)), after reciprocating a 2.5cm width coating film with a 2kg roller once and attached, 23 ℃ / 60%
Aged at RH for 24 hours and 180 degree peeling strength (peeling speed: 30
0 mm / min). The stainless steel plate is made of abrasive paper (#
280) after polishing.

Holding force A stainless steel plate (6.0 cm × 5.0 cm) is made by reciprocating one end of a coated film (2.5 cm × 5 cm) with a 2 kg rubber roller.
Attached to the area of 2.5cm x 2.5cm, and 1kg on the other end
Weighted. After aging this sample at 60 ° C for 20 minutes,
The sample was suspended in an atmosphere of 60 ° C., and the displacement of the coated film after 8 hours was measured.
NC (No Creep) and the size of the gap and the falling time were described.

Water-whitening 4.5cm × 4.5cm coated film (no release film)
A glass cell filled with water (5.0cm x 5.0cm, width 4mm)
Put the pressure-sensitive adhesive layer directly into the water and quickly set the glass cell on a reflection / transmittance meter HR-100 (Murakami Color Research Laboratory Co., Ltd.) and measure the haze value of 0 hour immersion After immersion in water at room temperature for 24 hours, the haze value was measured. The haze value of the water whitening resistance was determined by subtracting the haze value at 0 hour from the haze value after immersion in water for 24 hours. Therefore, the lower the haze value, the better the whiteness, which means no whitening.

Example 2 The seed of Example 1 and the amount of methyl methacrylate in each step were all 4.24 g, and the seed amount of lauryl methacrylate was 63.6 g, 128.48 g in the first step, and 4.24 g in the second step.
An emulsion was prepared in the same manner as in Example 1 except that the seed amount of 2-ethylhexyl acrylate was 55.1 g, the first stage was 108.1 g, and the second stage was 110.2 g. The final emulsion had a particle size of 0.15 μm and a solids content of 52%. Further, as in Example 1,
A tackifier and a thickener were added to prepare a water-based pressure-sensitive adhesive composition, a coated film was prepared in the same manner, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

Example 3 2,2'-azobis (2-
1.27 g of methylbutyronitrile) was 1.27 g of benzoyl peroxide, and the amount of lauryl methacrylate was 127.2 g.
g, the amount of 2-ethylhexyl acrylate as seed 1
11.9 g, 67.4 g in the first stage, 65.3 g in the second stage, 85
An emulsion was prepared in the same manner as in Example 1 except that the temperature was raised to ° C and polymerization was carried out while keeping the temperature constant.
The final emulsion has a particle size of 0.17 μm and a solids content of
52%. Further, in the same manner as in Example 1, a tackifier and a thickener were added to prepare a water-based pressure-sensitive adhesive composition, and similarly, a coated film was prepared, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

Example 4 127.2 g of decyl acrylate was used in place of lauryl methacrylate as a seed in Example 1, 21.2 g of methyl methacrylate as a seed, 61.5 g of 2-ethylhexyl acrylate, 2.12 g of styrene, 2.12 g of n-dodecyl. 0.055 g of mercaptan, 6.36 g of acrylic acid in the first stage,
Change methyl methacrylate to 21.2 g, 2-ethylhexyl acrylate to 182.3 g, styrene to 2.12 g, n-dodecyl mercaptan to 0.055 g, S-180 to 5.60 g, and water to 41 g. Was carried out in the same manner as in Example 1 except that emulsion was not prepared. The final emulsion had a particle size of 0.27 μm and a solids content of 52.7%. SPE- as a wetting agent
503 [Kao Co., Ltd.] is added at 1.5% to the solid content,
By performing the same operation as in Example 1 except that a 20% aqueous solution of Primal RM-2020NPR (manufactured by Rohm & Haas) is used instead of Primer TT-935 as a thickener,
A water-based pressure-sensitive adhesive composition was prepared, a coated film was prepared in the same manner, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

Comparative Example 1 In a separable container, lauryl methacrylate 31.8 g, acrylic acid 6.36 g, methyl methacrylate 42.2 g, 2-ethylhexyl acrylate 339.2 g, styrene 4.22 g,
0.11 g of n-dodecyl mercaptan, 1.27 g of 2,2′-azobis (2-methylbutyronitrile) and 0.21 g of t-butyl peroxide were mixed and stirred, and the monomer solution was dissolved in
12.7 g of S-180 was dropped and dispersed in an aqueous solution of 376 g of water. The suspension is mixed with an ultrasonic homogenizer for 4 hours.
An emulsion was prepared by forcibly emulsifying and dispersing for minutes. The particle size of the emulsion was measured to be 0.36 μm. While introducing nitrogen into the separable container for 10 minutes, the emulsion was stirred, and 1.28 g of an aqueous solution in which 0.5 g of L-ascorbic acid as a redox initiator was dissolved in 10 g of water was added. After that, the temperature inside the system was adjusted to 5 ° C in 15 minutes, and the temperature was raised to 75 ° C.
The stirring was performed in the state of. After completion, the mixture was cooled, neutralized with a 25% aqueous ammonia solution, and adjusted to pH 7.0 to 7.3. The particle size of the emulsion after polymerization is 0.60 μm, and the solid content is 53%.
%Met. Further, a tackifier and a thickener were added in the same manner as in Example 1 to prepare a water-based pressure-sensitive adhesive composition. Similarly, a coated film was prepared, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

Comparative Example 2 The same procedure as in Example 1 was carried out except that lauryl methacrylate added in Example 1 was not used and the amount of 2-ethylhexyl acrylate added to the seed was changed to 125.9 g. An emulsion was prepared. The final emulsion had a particle size of 0.12 μm and a solids content of 46%.
Further, in the same manner as in Example 1, a tackifier and a thickener were added,
A water-based pressure-sensitive adhesive composition was prepared, a coated film was prepared in the same manner, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

Comparative Example 3 Without using decyl acrylate, 63.6 g of lauryl methacrylate was used in each of the seed and the first stage.
-125.1 ethylhexyl acrylate in seed
g, an emulsion was prepared in the same manner as in Example 4 except that in the first step, the amount was 118.7 g, and acrylic acid was put in the seed, and was not used in the first step. The particle size of the final emulsion was 0.71 μm, and the solid content was 52.5%. Further, in the same manner as in Example 1, a tackifier and a thickener were added to prepare a water-based pressure-sensitive adhesive composition, and similarly, a coated film was prepared, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

Comparative Example 4 Without using lauryl methacrylate added to the seed of Example 1, 31.8 g was added in the second stage, and the amount of 2-ethylhexyl acrylate was changed to 125.9 g in the seed and to the first stage. An emulsion was prepared in the same manner as in Example 1 except that 123.8 g and 89.9 g were used in the second stage.
The particle size of the final emulsion is 0.55 μm and the solid content is
50.5%. Further, as in Example 1, a tackifier,
A thickener was added to prepare a water-based pressure-sensitive adhesive composition. Similarly, a coated film was prepared, and the adhesive performance was evaluated. Table 1 shows the emulsion composition ratio and particle size, and Table 2 shows the evaluation results.

[0037]

[Table 1]

Note) * 1: Abbreviations have the following meanings. LMA: lauryl methacrylate DA: decyl acrylate MMA: methyl methacrylate 2-EHA: 2-ethylhexyl acrylate St: styrene n-DM: n-dodecyl mercaptan S-180: latemul S-180 [Reactive surfactant / Kao Corp.
V-59: 2,2'-azobis (2-methylbutyronitrile) BPO: benzoyl peroxide tBuHP: t-butyl hydroperoxide AsA: L-ascorbic acid * 2: Indicates the weight% based on the total monomer amount. .

[0039]

[Table 2]

[0040]

Industrial Applicability According to the present invention, a water-based texture having an excellent balance of adhesive properties such as adhesion to curved surfaces, holding power and water resistance, as well as adhesiveness to non-polar adherends which are generally difficult to adhere to such as polyolefins. A pressure-sensitive adhesive composition can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing evaluation criteria for curved surface adhesiveness.

[Explanation of symbols]

 1 Coated film 2 High density polyethylene rod

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasuhiro Doi 1334 Minato, Wakayama-shi, Wakayama Prefecture F-term in the Kao Corporation Research Institute (Reference) 4J004 AA10 CA04 CA06 CC02 DB02 FA01 FA04 GA01 4J011 PA69 PB40 PC02 PC06 PC09 4J026 AA17 AA43 AA45 AA53 AC36 BA05 BA25 BA27 BA34 BB03 BB04 DA04 DA09 DA10 DA12 DA14 DA15 DA16 DB04 DB10 DB12 DB14 DB15 DB16 DB22 DB26 DB29 DB31 DB32 FA04 GA08 GA09 4J040 DL121 GA07 JA03 JA09 JB09 KA11 LA06 LA07 MA11 QA01 4J100 AL02AJR04 CA05 CA29 EA07 FA02 FA03 FA20 FA35 FA37 JA03 JA05

Claims (5)

[Claims] 1. A seed emulsion comprising a polymer emulsion obtained by sequentially supplying a monomer emulsion in the presence of a polymerization initiator in multiple stages or in one stage to carry out polymerization, wherein the seed emulsion has an alkyl group having 9 carbon atoms. ~ 14 long-chain alkyl (meth) acrylates (hereinafter simply referred to as long-chain alkyl (meth) acrylates)
70% by weight or more, and in each step of the monomer emulsion sequentially fed, the main component is a short-chain alkyl (meth) acrylate having an alkyl group of 8 or less carbon atoms, and the balance
Less than 30% by weight of long-chain alkyl (meth) acrylate is used in less than 10% by weight of the total amount used in each of the multi-step or one-step, and the long-chain alkyl (meth) acrylate is used in all monomer compositions (seed and all steps successively). A water-based pressure-sensitive adhesive composition containing 2 to 80% by weight based on the total composition of the supplied monomers (hereinafter the same). 2. An α, β-unsaturated monocarboxylic acid or dicarboxylic acid is used in an amount of 0.5 to 5.0% by weight based on the total monomer composition.
2. The water-based pressure-sensitive adhesive composition according to claim 1, wherein the water-based pressure-sensitive adhesive composition is contained in an amount of 0.5% by weight or more based on the total monomer composition. 3. The method according to claim 1, wherein the content of methyl methacrylate is at least 5% by weight based on the total monomer composition, and the content of the seed and the monomers supplied sequentially at all stages is always at least 1.0% by weight based on the total monomer composition. Water-based pressure-sensitive adhesive composition. 4. A method for producing a water-based pressure-sensitive adhesive composition by sequentially supplying a monomer emulsion to a seed emulsion in the presence of a polymerization initiator in multiple stages or in one stage in order to obtain a water-based pressure-sensitive adhesive composition. At least 70% by weight of the total amount of the alkyl (meth) acrylate used, and in each stage of the monomer emulsion successively supplied, the main component is a short-chain alkyl (meth) acrylate having 8 or less carbon atoms in the alkyl group, and the balance is 30% by weight. % Or less of the long-chain alkyl (meth) acrylate is used in less than 10% by weight of the total amount used in each of the multi-step or one-step, and the long-chain alkyl (meth) acrylate is used in an amount of 2 to 80% by weight based on the total monomer composition. And a method for producing a water-based pressure-sensitive adhesive composition. 5. A pressure-sensitive adhesive product obtained by applying the aqueous pressure-sensitive adhesive composition according to claim 1 to a substrate.