JP2001303007A - Acrylic resin emulsion for pressure sensitive peelable adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition having a slight tackiness of a coated surface, a moderate adhesive strength and a slight detereoration in the adhesive strength with time and suitable as a pressure sensitive peelable adhesive. SOLUTION: This acrylic resin emulsion for the pressure-sensitive peelable adhesive is characterized as the emulsion is obtained by carrying out an emulsion polymerization of a monomer component containing an acrylic monomer and satisfies the following conditions. (i) -50 to 0 deg.C glass transition temperature of the polymer obtained by the emulsion polymerization, (ii) 20-95 wt.% content of a fraction of a film formed from the emulsion insoluble in tetrahydrofuran, (iii) 100,000-800,000 weight-average molecular weight of the fraction of the film soluble in tetrahydrofuran and (iv) >=0.29 N/mm2 maximum tensile strength of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an acrylic resin emulsion for a pressure-sensitive removable adhesive.

[0002]

2. Description of the Related Art A pressure-sensitive re-peelable adhesive means that the coated surfaces of the adhesive applied to a substrate or the coated surface and the non-coated surface are overlapped and bonded by mechanical pressure. Adhesive that can be peeled off without destruction of the material of the base material at the time of peeling. For example, adhesives for sealing mail, adhesives used for confidential postcards for privacy protection of personal information, delivery slips It is used as an adhesive for information carrier sheets, such as an adhesive for paper.

[0003] As a resin component in such an adhesive, natural rubber latex has been widely used because of its low tackiness on the coated surface and moderate adhesive strength. However, natural rubber latex is oxidatively degraded,
There is a problem that the adhesive strength changes with time due to deterioration due to ultraviolet rays or the like.

[0004] In order to solve this problem, a natural rubber latex is modified by mixing an acrylic emulsion with little oxidative deterioration and ultraviolet deterioration, and a (meth) acrylate monomer is polymerized in the presence of the natural rubber latex. Modification and the like have been carried out, and further studies have been made to give the acrylic emulsion itself a performance like natural rubber latex.

[0005] Against this background, various reports have been made of acrylic emulsion resins having a low tackiness comparable to that of natural rubber latex and a good adhesive property (Japanese Patent Application Laid-Open No. 9-194812, JP-A-10-
158615, JP-A-10-158616, etc.).

However, even with these acrylic resin emulsions, the state of the dried film changes depending on the storage conditions and the length of time from application to the substrate and drying to pressure bonding, and the adhesive strength after pressure bonding may also change. It is a problem. As a result, for example, if the adhesive strength becomes too large, it becomes impossible to re-peel and causes destruction of the base material when peeling, and if the adhesive strength is reduced, spontaneous peeling occurs and the like. .

[0007]

SUMMARY OF THE INVENTION The main object of the present invention is to:
An object of the present invention is to provide a resin composition suitable as a pressure-sensitive re-peelable adhesive which has a small tackiness on a coated surface, has an appropriate adhesive strength, and has little change in adhesive strength with time.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above-mentioned object, and as a result, have obtained an emulsion obtained by emulsion polymerization of a monomer component containing an acrylic monomer. Of the film formed by the emulsion, the insoluble matter in tetrahydrofuran of the film formed by the emulsion, the weight average molecular weight of the soluble matter in tetrahydrofuran of the film, and the maximum tensile strength of the film all within the specified range at the same time. The present inventors have found that a resin emulsion can achieve the above-mentioned object, and have completed the present invention.

That is, the present invention provides the following acrylic resin emulsion for a pressure-sensitive removable adhesive. 1. An emulsion obtained by emulsion polymerization of a monomer component containing an acrylic monomer, wherein the acrylic resin emulsion for a pressure-sensitive removable adhesive is characterized by satisfying the following conditions: (i) a weight obtained by emulsion polymerization; The glass transition temperature of the coalesced is -50 ° C to 0 ° C, and (ii) the film formed by the emulsion has an insoluble content in tetrahydrofuran of 20 to 20 ° C.
95% by weight, (iii) the weight-average molecular weight of the soluble portion of the film in tetrahydrofuran is from 100,000 to 800,0
00, (iv) the maximum tensile strength of the coating is 0.29 N / mm
² or more. 2. The acrylic resin emulsion for a pressure-sensitive removable adhesive according to claim 1, wherein the monomer component contains an acrylic monomer and a crosslinkable monomer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The emulsion of the present invention is an acrylic resin emulsion obtained by emulsion polymerization of a monomer component containing an acrylic monomer, wherein the polymer in the emulsion is a homopolymer of an acrylic monomer or It is a copolymer of an acrylic monomer and another copolymerizable monomer.

As the acrylic monomer used for producing the emulsion, alkyl acrylate, alkoxyalkyl acrylate, etc. may be used, and these monomers may be used alone or in combination of two or more. . Examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isononyl acrylate, and the like. As the alkoxyalkyl acrylate, 2-methoxy acrylate Examples thereof include ethyl, 2-ethoxyethyl acrylate, and 2-butoxyethyl acrylate. These acrylic monomers can be used alone or in combination of two or more.

Further, as the monomer component, a monomer copolymerizable with the acrylic monomer can be used, if necessary, in addition to the above-mentioned acrylic monomer.
Such monomer components include methyl methacrylate,
Alkyl methacrylates such as ethyl methacrylate, acrylonitonyl, methacrylonitonyl, styrene, vinyl acetate, (meth) acrylic acid, maleic anhydride, itaconic acid, (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, Diethylene glycol mono (meth) acrylate, N-methylol (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate,
Examples thereof include (meth) acryloyloxyethyl phosphate, sodium vinyl sulfonate, and sodium styrene sulfonate. These monomer components can be used alone or in combination of two or more. By using a monomer copolymerizable with these acrylic monomers, it is possible to adjust the Tg of the resin component and to improve the stationary stability and mechanical stability of the emulsion.

In addition, if necessary, a crosslinkable monomer can be used as a monomer copolymerizable with the acrylic monomer. Examples of the crosslinking monomer include divinylbenzene, allyl (meth) acrylate,
Triallyl (iso) cyanurate, diallyl (iso) phthalate, diallyl (iso) phthalate, diallyl terephthalate diallyl dimethyl ammonium chloride,
Allyl group-containing monomers such as trimethylolpropane diallyl ether and pentaerythritol triallyl ether; N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) ) Acrylamide, N-butoxymethyl (meth)
Monomers containing an N-methylol group or an N-alkoxymethyl group such as acrylamide; 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, 1,3-butanediol diacrylate, 1, 4-
Examples thereof include butanediol diacrylate, diethylene glycol diacrylate, pentaerythritol triacrylate, and ditrimethylolpropane tetraacrylate. The crosslinkable monomers can be used alone or in combination of two or more. When a crosslinkable monomer is used, the THF-insoluble content and Mw of the obtained copolymer can be increased. In particular, when an allyl group-containing monomer is used among the crosslinkable monomers, the tack on the coated surface is reduced, and the adhesive strength can be improved.

In the present invention, it is preferable to use about 50% by weight or more of the above-mentioned acrylic monomer in all the monomer components.

When a crosslinkable monomer is used, the amount of the crosslinkable monomer used is preferably about 1% by weight or less based on all the monomer components, since the effect of using the crosslinkable monomer is effectively exhibited. 0.1 to 0.
More preferably, it is about 5% by weight. Even if the crosslinking monomer is excessively mixed, the THF-insoluble content and Mw do not further increase, and gelation during polymerization, a decrease in initial adhesive strength, cracks during film formation, and the like are likely to occur. Is not preferred.

In the present invention, the above-mentioned monomer component has a glass transition temperature (Tg) of a polymer obtained by emulsion polymerization.
It is necessary to select a temperature in the range of about -50 ° C to 0 ° C, preferably about -30 ° C to -10 ° C. Tg
However, if the temperature is lower than −50 ° C., the tack on the coated surface becomes too strong,
Conversely, if the Tg exceeds 0 ° C., the adhesiveness is undesirably reduced. The Tg of the polymer is determined by differential scanning calorimetry (DS
C) actual measurement, or J. Brandrup and EHImmergut, P
olymer Handbook Third Edition, John Wiley & Sons (1
It can be calculated from the glass transition temperature (Tg) of the homopolymer of each monomer described in 989) by the following equation (1).

1 / Tg = W1 / Tg1 + W2 / Tg2 +... Wn / Tgn (1) where Tg is the glass transition temperature (absolute temperature) of the copolymer W1 to Wn are the monomer components 1 to n Weight fractions Tg1 to Tgn are glass transition temperatures (absolute temperatures) of homopolymers of monomer components 1 to n. Regarding typical monomer components that can be used to prepare the emulsion of the present invention, homopolymers composed of the monomer components To give an example of the glass transition temperature of
It is as follows.

Methyl acrylate: + 8 ° C, ethyl acrylate: -19 ° C, butyl acrylate: -52 ° C, 2-ethylhexyl acrylate: -74 ° C, 2-methoxyethyl acrylate: -45 ° C, acrylic acid 2 -Ethoxyethyl: -50 ° C, methacrylic acid: 120 ° C, styrene: 1
05 ° C, vinyl acetate: 29 ° C, acrylonitrile: 10
4 ° C., acrylic acid: 106 ° C. Further, when the emulsion of the present invention forms a film from the emulsion, the formed film has a tetrahydrofuran (THF) -insoluble content of 2%.
0 to 95% by weight, and a weight-average molecular weight (hereinafter, referred to as Mw) of the THF-soluble component by GPC is 100,000 to 80.
It needs to be 0000. By satisfying such conditions, an emulsion having a small change in adhesive strength with time can be obtained.

In the present specification, the THF-insoluble component is
23 ° C, 50% humidity using the emulsion to be measured
Cured for 24 hours to form a 0.3 mm thick film, cut this film into 2 cm squares,
After immersion in HF at 23 ° C. for 24 hours, the mixture was filtered through a 200-mesh filter, and the value was obtained from the dry weight of the residue remaining by filtration according to the following formula.

THF-insoluble content [%] = (weight of filtration residue / T
The weight average molecular weight of the THF-soluble component was determined by gel permeation chromatography (GPC) for the THF-soluble component obtained by the measurement of the THF-insoluble component. It is.

When the THF-insoluble content is out of the above range, TH
Even when the Mw of the F-soluble component is in the range of 100,000 to 800,000, the adhesive strength is liable to decrease with time.
Even if the THF-insoluble content is in the range of 20 to 95% by weight,
If the Mw of the THF-soluble component is out of the above range, the adhesive strength tends to decrease with time, which is inappropriate.

Further, the emulsion of the present invention requires that the formed film has a maximum tensile strength of 0.29 N / mm ² or more. Maximum tensile strength is 0.29 N / mm ²
If the ratio is lower than the above, the adhesive strength becomes low, so that it is not practical.

The maximum tensile strength of the film is as follows: a film having a thickness of 3 mm obtained by curing at 23 ° C. and 50% humidity for 24 hours has a crosshead speed of 200 mm / 25 ° C.
The tensile test is performed in minutes, the load at the time of breaking of the film is measured, and the value is obtained by the following equation.

T_B= F_B/A×0.098 T_B : Maximum tensile strength [N / mm^Two]  F_B : Maximum load [Kgf]  A ： Cross-sectional area of test piece [cm^Two] The acrylic resin emulsion of the present invention is the above-mentioned monomer.
-Emulsion polymerization reaction
Can be. Emulsion polymerization can be performed according to a conventional method.
For example, under stirring in a water medium in the presence of an emulsifier,
Nomer and polymerization initiator are supplied at once or continuously.
Can be carried out. Monomer
Supply as is, or use monomer and water with emulsifier
It can be supplied as a marsion.

The final monomer concentration in the aqueous medium is usually about 30 to 70% by weight, preferably 35 to 65% by weight.
It should be about the degree.

Examples of the emulsifier include a reactive emulsifier having a polymerizable double bond in a molecule, a general emulsifier having no polymerizable double bond in a molecule (general-purpose emulsifier), and a water-soluble emulsifier called a protective colloid. A polymer or the like can be used. These emulsifiers can be used alone or in combination of two or more.

Among these emulsifiers, the reactive emulsifier is an emulsifier having a polymerizable double bond such as an allyl group, a residue of (meth) acrylic acid, or a residue of maleic acid in the molecule. When a reactive emulsifier is used, the migration of the emulsifier is suppressed by binding of the emulsifier to the polymer particles, so that the decrease in adhesion is very small. Examples of the reactive emulsifier include Adecaria Soap SE-10N (trade name: manufactured by Asahi Denka Kogyo Co., Ltd.), Latemul S-180 (trade name: manufactured by Kao Corporation), Eleminor JS-2 (trade name: Sanyo Chemical Industry Co., Ltd.) )), Aqualon HS-10 (trademark: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Antox MS-60 (trademark: manufactured by Nippon Emulsifier Co., Ltd.), and the like.

The general-purpose emulsifier is an emulsifier which does not contain a polymerizable double bond in the molecule, and specific examples thereof include potassium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkylsulfonate,
Anionic emulsifiers such as sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl allyl ether sulfate, and polyoxyethylene alkyl ether phosphate;
Nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropylene block polymer, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester; lauryl betaine;
Zwitterionic emulsifiers such as lauryl dimethylamine oxide can be exemplified.

Also, an aqueous solution polymer (protective colloid agent)
As, hydroxycellulose, methylcellulose,
Carboxycellulose, gelatin, casein, polyvinyl alcohol, solubilized starch, modified polyvinyl alcohol, styrene / maleic acid copolymer, its alkali salt, alkali salt of isoprene / maleic acid polymer, sodium poly (meth) acrylate, acrylamide Acrylic acid ester copolymer, (meth) acrylic acid copolymer,
A (meth) acrylic acid / (meth) acrylic ester copolymer, an alkali salt thereof, or the like can be used. When a water-soluble monomer is used, aggregation during polymerization can be suppressed, and the tack on the coated surface can be reduced.

The total amount of the emulsifier is preferably about 0.5 to 3 parts by weight, based on 100 parts by weight of the total amount of the monomer components. If the amount of the emulsifier is less than 0.5 part by weight, it becomes difficult to obtain a stable emulsion by aggregating during polymerization, while if it is more than 3 parts by weight, the adhesive strength of the obtained emulsion will increase with time. It is not preferable because it tends to decrease.

As the polymerization initiator, generally used radical polymerization initiators, for example, ammonium persulfate,
Persulfates such as potassium persulfate; azo-based polymerization initiators such as 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvaleronitrile); t-butyl hydroperoxide And peroxide-based initiators such as benzoyl peroxide and lauroyl peroxide. The used amount of the radical polymerization initiator, the total amount of the monomer components as 100 parts by weight,
The amount may be about 0.05 to 5 parts by weight, preferably about 0.05 to 1 part by weight.

The reaction temperature during the emulsion polymerization is usually 20 to 90 ° C.
However, if the polymerization temperature is too high, a low molecular weight component is easily generated during the polymerization reaction.
It is preferable to set the range. The reaction time is usually 1
The time may be about 16 hours, preferably about 2 to 8 hours.

In order to smoothly carry out the polymerization at a low temperature of about 50 ° C. or less, a reducing agent may be used in combination with the radical polymerization initiator. Examples of the reducing agent include sodium hyposulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate and the like. The reducing agent is usually used in a weight ratio of about 1/10 to 1/1 with respect to the polymerization initiator.

Further, by adding a chain transfer agent at the time of emulsion polymerization, it becomes easy to suppress gelation during polymerization. Examples of the chain transfer agent include mercaptans such as methyl mercaptan, butyl mercaptan, octyl mercaptan, dodecyl mercaptan, alcohols such as methanol, ethanol, isopropyl alcohol, and hexanol, and α-styrene dimer. These chain transfer agents can be used alone or in combination of two or more.

The chain transfer agent can be used within a range that does not reduce the THF-insoluble content and Mw, and is generally 0.01 to 100 parts by weight based on 100 parts by weight of the total amount of the monomer components used.
It is preferable to use about 0.1 part by weight.

In order to control the amount of the THF-insoluble component and the weight-average molecular weight of the THF-soluble component in the obtained acrylic resin emulsion within the respective requirements in the present invention, for example, an appropriate amount of the monomer component may be adjusted. Combination, emulsion polymerization at relatively low temperature, use of peroxide-based initiator,
Methods such as reduction in the amount of the polymerization initiator used, use of a water-soluble polymer as an emulsifier, and combined use of a crosslinkable monomer may be appropriately combined.

Further, the maximum tensile strength of the film is set to 0.29 N /
mm ² or more, for example, emulsion polymerization is performed by appropriately combining a monomer having a low Tg and a monomer having a high Tg when forming a homopolymer, a polymerization temperature of 65 ° C. or lower during emulsion polymerization, It is effective to reduce the amount of the initiator.

The acrylic resin emulsion of the present invention has an excellent characteristic that it has a small tackiness on the coated surface, has an appropriate adhesive strength, and hardly causes a change in the adhesive strength due to aging and a change in the adhesive strength due to storage conditions. It has.

The acrylic resin emulsion of the present invention is used as a resin component for a pressure-sensitive removable adhesive, for example, an adhesive for sealing mail, an adhesive for delivery slips, a confidential postcard, and a direct ad for advertising. It can be effectively used as a cold seal adhesive for mails and the like.

The cold seal adhesive can be bonded by applying high pressure between the coated surface and the non-coated surface or between the coated surfaces, and is required to have such a property that once separated, it does not re-adhere in a normal state. Things. In order to prepare such adhesive properties, a filler such as corn starch, calcium carbonate, silica, kaolin, clay, talc, titanium oxide, zinc oxide, and shirasu balloon is usually blended with the acrylic resin emulsion. The average particle diameter of the filler is preferably about 1 to 20 μm, and the compounding amount is usually preferably in the range of about 5 to 100 parts by weight based on 100 parts by weight of the nonvolatile content of the acrylic resin emulsion.

[0041]

The acrylic resin emulsion of the present invention comprises:
It has excellent characteristics such as low tack on the coated surface, moderate adhesive strength, and little change in adhesive strength with time. A peelable adhesive is obtained.

Such pressure-sensitive removable adhesives include, for example, postcards such as three-fold postcards, two-fold postcards, partially foldable postcards, printing paper, copy paper, and courier form slips. It is particularly useful as a pressure-sensitive adhesive for sheets.

[0043]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel was charged with 150 g of water and heated to 70 ° C. Next, 12 g of a 10% aqueous solution of ammonium persulfate was added with stirring. On the other hand, 240 g of methyl acrylate, 250 g of ethyl acrylate, 10 g of acrylic acid, 20 g of an anionic reactive emulsifier (trade name: Eleminol JS-2, manufactured by Sanyo Chemical Industries, Ltd., active ingredient 38%) and water 22
A monomer emulsion composed of 5 g was continuously dropped into the reaction vessel with a dropping funnel over 4 hours. During this period, the polymerization temperature was maintained at 60 ° C., and after completion of the dropwise addition, an aging reaction was performed at 60 ° C. for 2 hours. After the reaction, the reaction solution was allowed to cool to 30 ° C.
An acrylic copolymer resin emulsion having a viscosity of 2,000 mPa · s and a pH of 6.8 was obtained at 5%.

Examples 2 to 7 and Comparative Examples 1 to 5 An aqueous emulsion was obtained in the same manner as in Example 1 except that the components shown in Table 1 below were used. The nonvolatile content, viscosity and pH of the obtained emulsion are shown in Table 1 below. The glass transition temperature (Tg), the weight-average molecular weight of the THF-insoluble component, and the maximum tensile strength of the THF-soluble component were measured for each of the emulsions obtained by the above-described methods. (1) Measurement method of Tg The emulsion to be measured was cast on a Teflon (registered trademark) sheet and cured at 23 ° C. and a humidity of 50% for 24 hours to form a 0.3 mm thick film. Vacuum dried at ℃ for 24 hours to prepare a sample. The Tg was measured using a DSC220C model manufactured by Seiko Denshi Co., Ltd.
mg, at a heating rate of 10 ° C./min. (2) Method of measuring THF-insoluble content The emulsion to be measured is cast on a Teflon sheet,
Cured at 23 ° C, 50% humidity for 24 hours, 0.3m thick
m was prepared. Then, this film is 2 cm
It was cut into corners, immersed in 100 ml of THF at 23 ° C. for 24 hours, filtered through a 200-mesh filter, and the filtration residue was dried and weighed to determine the THF-insoluble content by the following formula.

THF-insoluble content [%] = (weight of filtration residue / T
(Weight before immersion in HF) × 100 (3) Method for measuring molecular weight (GPC) of THF-soluble component The concentration of the filtrate obtained in the above measurement of the THF-insoluble component was adjusted to 0.2 wt% / vol (THF), and GPC measurement was performed. Using a 6A series manufactured by Shimadzu Corporation as a sample for use, the weight average molecular weight (GPC) of the THF-soluble component was measured under the following conditions.

Flow rate: 1 ml / min Column: PL gel 10 μm Mix B (manufactured by Polymer Laboratories) Standard sample: monodispersed PS (manufactured by Polymer Laboratories) Detector: RI (4) Measuring method of maximum tensile strength Measurement Cast the emulsion of interest on a Teflon sheet,
The film was cured at 23 ° C. and 50% humidity for 24 hours to prepare a film having a thickness of 3 mm. The film was subjected to a crosshead speed of 2 at 25 ° C. using an autostrain.
A tensile test was performed at 00 mm / min, the load at the time of breaking of the film was measured, and the maximum tensile strength of the film was determined by the following equation.

T_B= F_B/A×0.098 T_B : Maximum tensile strength [N / mm^Two]  F_B : Maximum load [Kgf]  A ： Cross-sectional area of test piece [cm^TwoThe above measurement results are shown in Table 1 below. still. About Tg
Indicates an actual measurement by the above measurement method
Values are unmarked and calculated values are calculated values.Measurement of adhesive strength retention About each emulsion of each of the above Examples and Comparative Examples,
And 100 parts by weight of non-volatile content, flour starch
(Product name: Cornstar, manufactured by Hoshun Corporation)
And silica (Nippon Silica Co., Ltd.)
Manufactured by Sangyo Co., Ltd., trade name: E-220A, average particle size about 1.
5μm) each for 25 parts by weight and cold seal adhesive
An agent was prepared. About 8 g / m of this adhesive is applied to high quality paper
^TwoApply using a bar coater so that
After drying at 105 ° C for 2 minutes using a dryer,
The uncoated surface is crimped by the gap method and cut to a width of 100 mm.
Thus, a sample for measuring adhesive strength was obtained.

After measuring the adhesive strength (initial adhesive strength) immediately after coating of each of these samples, the sample was heated at 20 ° C. and a humidity of 60 ° C.
% For 7 days, and the adhesive strength of each sample after standing was measured. The adhesive strength retention was determined by the following equation.

Adhesive strength retention [%] = (Adhesive strength after standing / initial adhesive strength) × 100 Tack evaluation of coated surface The adhesive for cold seal prepared in the same manner as in the above-mentioned method of measuring the adhesive strength retention was used. After coating on paper, the state of the coated surface was determined by finger touch.

◎ indicates no stickiness when touched by a finger, x indicates large stickiness, and ○ indicates a medium stickiness.

The above results are shown in Table 1 below.

The symbols in Table 1 below have the following meanings.

MA: methyl acrylate EA: ethyl acrylate BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate n-OA: normal octyl acrylate AN: acrylonitrile AA: acrylic acid AMA: allyl methacrylate VAC: vinyl acetate TAIC: triallyl isocyanurate JS -2: Eleminor JS-2 (trade name, manufactured by Sanyo Chemical Industries, Ltd .; reactive emulsifier) HS-10: Aqualon HS-10 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; reactive emulsifier) ES- 70: Elemisol ES-70 (trade name, manufactured by Sanyo Chemical Industries, Ltd .; general-purpose emulsifier) SMA: styrene / maleic acid copolymer (manufactured by Elf Atochem Co., Ltd., trademark: SMA resin SMA1000: protective colloid agent) L3266: Gooselan L-326 6 (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd .; protective colloid agent) NOM: normal octyl mercaptan (chain transfer agent)

[0055]

[Table 1]

Continued on the front page F-term (reference) 4J011 KA01 KA04 KA05 KA10 KA15 KA16 KA17 KB02 4J040 DB022 DF012 DF041 DF042 DF052 DF082 DF092 DJ012 DJ022 JA03 JA12 JB09 LA01 LA02 LA06 LA07 MA09 MB03 NA16 NAQ4QQQA1QB AL66Q AL67Q AL75Q AM21Q AN14Q AQ20Q BA02Q BA03Q BA04P BA04Q BA05P BA05Q BA06P BA06Q BC75Q CA04 DA25 DA40 EA06 FA20 JA03

Claims (2)

[Claims] 1. An emulsion obtained by emulsion polymerization of a monomer component containing an acrylic monomer, wherein the emulsion satisfies the following conditions: (i) emulsification The polymer obtained by polymerization has a glass transition temperature of -50 ° C to 0 ° C, and (ii) a film formed by the emulsion has an insoluble content in tetrahydrofuran of 20 to 20 ° C.
95% by weight, (iii) the weight-average molecular weight of the soluble portion of the film in tetrahydrofuran is from 100,000 to 800,0
00, (iv) the maximum tensile strength of the coating is 0.29 N / mm
² or more. 2. The acrylic resin emulsion for a pressure-sensitive removable adhesive according to claim 1, wherein the monomer component contains an acrylic monomer and a crosslinkable monomer.