JPH09286963A - Acrylic water-base pressure-sensitive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject adhesive, excellent in adhesive strength to a polyolefin, etc., tack cohesion, fabricability, etc., and useful in the fields of pressure-sensitive adhesive tapes, films, labels, etc., by dispersing a specific acrylic copolymer and a tackifier in an aqueous medium in specific proportions. SOLUTION: This acrylic water-based pressure-sensitive adhesive is obtained by dispersing (A) an acrylic copolymer having <=-40 deg.C glass transition temperature and (B) a tackifying resin having 70-180 deg.C softening point and <=5000 weight-average molecular weight (e.g. a petroleum-based hydrocarbon resin) in an aqueous medium. The respective amounts of the components based on 100 pts.wt. total amount of the components A and B are 70-98wt.% component A and 2-30wt.% component B. The adhesive is prepared so as to provide 77-88% light transmittance of a film formed of the adhesive.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has excellent adhesive strength, particularly excellent curved surface adhesiveness and low-temperature adhesiveness, to slits and cuts, for films or molded products of non-polar polymers such as polyolefins. And secondary workability such as stamping and the like, and an acrylic water-based pressure-sensitive adhesive having excellent performance in terms of adhesive strength temporal stability, in detail, an acrylic copolymer having a specific glass transition point, and a specific An acrylic water-based pressure-sensitive adhesive obtained by blending a specific amount of a tackifying resin having a softening point and a specific average molecular weight, wherein the light transmittance of a film formed from the pressure-sensitive adhesive is within a specific range. One acrylic water-based pressure sensitive adhesive.

[0002]

BACKGROUND OF THE INVENTION Pressure sensitive adhesives are used for tapes, sheets,
It covers many fields such as labels, stickers, and wallpapers,
The material of the adherend is plastic, metal, glass, ceramics,
It covers a wide range, such as paper, cloth, wood, and fresh food products.

Conventionally, as a main raw material of a pressure-sensitive adhesive, natural rubber, synthetic rubber, ethylene-vinyl acetate copolymer, acrylic copolymer and the like have been dissolved in an organic solvent or dispersed in water. Has been used in the form. Among these, the water-dispersed form, that is, the pressure-sensitive adhesive mainly composed of a water-dispersed acrylic copolymer does not contain an organic solvent,
Since there is no fire or environmental health problems, it has been widely used.

However, the pressure-sensitive adhesive containing a water-dispersible acrylic copolymer as a main raw material has a higher water resistance and adhesive strength than a pressure-sensitive adhesive containing a solvent-type acrylic copolymer as a main raw material. In particular, there is a problem in that the adhesive force to a film or molded product of a non-polar polymer such as polyolefin tends to be insufficient.

As a typical attempt to improve the above-mentioned problems of a pressure-sensitive adhesive containing a water-dispersible acrylic copolymer as a main raw material, for example, JP-A-60-84371 discloses an aqueous medium. And a resin component, wherein the resin component has a glass transition temperature of -30 to -60 ° C obtained by copolymerizing a specific acrylic monomer, the acrylic copolymer 50 to 95% by weight, and the softening point. 70 ~
50-5% by weight of disproportionated rosin ester in the range of 130 ℃
An aqueous emulsion-type adhesive composition comprising the following is disclosed. This adhesive composition is intended to improve the adhesive strength particularly to polyolefin by incorporating a specific amount of a specific disproportionated rosin ester into a conventional acrylic emulsion.

However, the adhesive composition proposed above is
Adhesion of non-polar polymers such as polyolefins to adherends is certainly improved, but mechanical stability is insufficient, for example, emulsion particles tend to agglomerate into coarse particles, which may lead to noisles during coating. There are problems such as occurrence. The pressure-sensitive adhesive sheet obtained also has, for example, -10 to
At a low temperature of about + 5 ° C., the adhesive strength is reduced and it cannot be attached to an adherend, and when peeling, so-called discontinuous peeling occurs, which causes wrinkles on the surface of the adherend.

[0007]

DISCLOSURE OF THE INVENTION The present inventors maintain a good balance of the original properties as a pressure-sensitive adhesive, that is, tack, normal-state adhesive force, cohesive force, and storage stability, and As a result of repeated research to obtain an acrylic water-based pressure-sensitive adhesive excellent in adhesiveness to films and molded products, particularly curved surface adhesiveness and low temperature adhesiveness, for example,
An aqueous pressure-sensitive adhesive comprising an acrylic copolymer aqueous dispersion having a glass transition point in a specific range, and an aqueous dispersion of a tackifying resin having a softening point and an average molecular weight in a specific range in a specific amount. Acrylic water-based pressure-sensitive adhesive having a specific range of transmittance of light of a specific wavelength of a coating having a specific thickness formed from a pressure-sensitive adhesive is an excellent water-based pressure-sensitive adhesive that eliminates all the above problems. It has been found that, and the present invention has been completed.

[0008]

Means for Solving the Problems The present invention includes the following (A) and
Per 100% by weight of (B),

(A) 70 to 98% by weight of an acrylic copolymer having a glass transition point of -40 ° C or lower, and

(B) 2 to 30% by weight of a tackifying resin having a softening point of 70 to 180 ° C. and a weight average molecular weight of 5000 or less,

Is an acrylic water-based pressure-sensitive adhesive which is dispersed in an aqueous medium, wherein the film formed from the pressure-sensitive adhesive has a light transmittance of 77 to 88%. The purpose is to provide a water-based pressure-sensitive adhesive.

Hereinafter, the present invention will be described in detail. The acrylic copolymer that is the copolymer component (A) of the present invention is not particularly limited, but from the viewpoint of excellent physical properties of the pressure-sensitive adhesive obtained, the following monomer ( a-1) to (a-4),

(A-1) 50 to 99.9% by weight of an acrylate ester represented by the following general formula, whose homopolymer has a glass transition point of -20 ° C or lower,

CH ₂ = CH-COOR ¹ (wherein R ¹ represents a straight-chain or branched alkyl group having 2 to 12 carbon atoms)

(A-2) α, β-unsaturated mono- having 3 to 5 carbon atoms
Or di-carboxylic acid 0.1 to 5% by weight,

(A-3) A monomer having at least one functional group in the molecule in addition to one radically polymerizable unsaturated group, other than the above-mentioned monomers (b) and (c) 0 to 5% by weight of the monomer, and

(A-4) Comonomers other than the monomers (a-1) to (a-3), which are copolymerizable with the above monomers (a-1) to (a-3) 0-45% by weight,

Is an acrylic copolymer obtained by emulsion-polymerizing the above, wherein the glass transition point of the acrylic copolymer is -40.
It is preferably an acrylic copolymer having a temperature of ℃ or less.

The monomer (a-1) has the general formula CH ₂ = CH-
An acrylic acid ester represented by COOR ¹ , wherein R ¹ represents a linear or branched alkyl group having 2 to 12 carbon atoms, and the homopolymer thereof has a glass transition point of -20 ° C or lower. .

Examples of such groups R ¹ are ethyl group, n-propyl group, n-butyl group, i-butyl group, n-hexyl group, n-octyl group, i-octyl group, 2-ethylhexyl group. Group, n-nonyl group, i-nonyl group, n-decyl group, n-dodecyl group and the like.

Specific examples of the acrylic ester which is such a monomer (a-1) include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, n-hexyl acrylate and n- Examples thereof include octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate and i-nonyl acrylate.

Among these monomers (a-1), the alkyl group R ¹ of the monomer is n-butyl group, n-hexyl group, n-octyl group, i-octyl group, 2-ethylhexyl group. , An n-nonyl group,
i-nonyl group, n-decyl group and other linear or branched alkyl groups having 4 to 10 carbon atoms, particularly n-hexyl group, n-octyl group, i-octyl group, 2-ethylhexyl group, n-nonyl group Base,
It is preferable to use, as an essential component, an acrylate monomer which is a linear or branched alkyl group having 6 to 9 carbon atoms such as i-nonyl group.

Specific examples of such a monomer (a-1) include n-hexyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate and i-nonyl acrylate. Can be mentioned.

The amount of the monomer (a-1) used is such that the monomers (a-1) to (a
-4) in a total of 100% by weight, 50 to 99.9% by weight, preferably 55
˜98% by weight, more preferably 60 to 95% by weight, particularly preferably 65 to 90% by weight. When the amount of the monomer (a-1) used is at least the lower limit amount, the pressure-sensitive adhesive layer to be formed is preferable because the adhesive force, the tack and the cohesive force are well balanced, while the upper limit amount is used. The following is preferable because inconvenience such as insufficient cohesive force does not occur.

The monomer (a-2) is an α, β having 3 to 5 carbon atoms.
-Unsaturated mono- or di-carboxylic acid, and specific examples thereof include acrylic acid, methacrylic acid, itaconic acid,
Maleic acid, fumaric acid, crotonic acid, citraconic acid, etc. may be mentioned. Among these, acrylic acid,
More preferably, methacrylic acid is used.

The amount of the monomer (a-2) used is the amount of the monomer
In a total of 100% by weight of (a-1) to (a-4), generally 0.1 to 5% by weight, preferably 0.2 to 4% by weight, more preferably 0.3 to 3% by weight.
%, Particularly preferably 0.5 to 2% by weight. If the amount of the monomer (a-2) used is not more than the upper limit,
The pressure-sensitive adhesive layer thus formed is preferable because it does not cause inconveniences such as reduction in tack and water resistance. On the other hand, when the amount used is not less than the lower limit value, the mechanical stability of the obtained water-based pressure-sensitive adhesive and the adhesive force of the obtained pressure-sensitive adhesive layer are appropriate and the cohesive force is also excellent. It is preferable to select and use it appropriately within the usage range.

The above-mentioned monomer (a-3) is a monomer having at least one functional group in the molecule in addition to one radically polymerizable unsaturated group. -It is a monomer other than 2). Such a monomer (a-3), as a functional group, for example, an amide group or a substituted amide group, an amino group or a substituted amino group, a hydroxyl group, an epoxy group, a mercapto group or a silicon-containing group, etc. And a monomer having two or more radically polymerizable unsaturated groups in the molecule can also be used.

Specific examples of these monomers (a-3) include acrylamide, methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, Nn-butoxymethyl acrylamide,
Amide group- or substituted amide group-containing monomer such as Ni-butoxymethylacrylamide, N, N-dimethylacrylamide, N-methylacrylamide (preferably acrylamide, methacrylamide); for example, aminoethyl acrylate, N, N-dimethylamino Ethyl acrylate, N, N-
Amino group-containing or substituted amino group-containing unit such as diethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate (preferably N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate) Quantity;

For example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, methallyl alcohol (preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol) and other hydroxyl group-containing monomers; for example, epoxy such as glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, glycidyl methallyl ether (preferably glycidyl acrylate, glycidyl methacrylate) Group-containing monomer; mercapto group-containing monomer such as allyl mercaptan;

For example, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltri-i-propoxysilane, vinyltri-n-butoxysilane, vinyltris (2-methoxy). (Ethoxy) silane, vinyltris (2-hydroxymethoxyethoxy) silane, vinyltriacetoxysilane, vinyldiethoxysilanol, vinylethoxysiladiol, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, allyltrimethoxysilane , Allyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropyltris (2
-Methoxyethoxy) silane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3-acryloxypropyldimethylmethoxysilane, 2-acrylamidoethyltriethoxysilane, etc. body;

For example, divinylbenzene, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, ethylene glycol di (meth) acrylate,
1,2-Propylene glycol di (meth) acrylate, 1,3-
Propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di
Examples thereof include a monomer group having two or more radically polymerizable unsaturated groups such as (meth) acrylate, trimethylolpropane tri (meth) acrylate, and allyl (meth) acrylate.

The amount of these monomers (a-3) used is the amount of the monomers (a-
The total amount of 1) to (a-4) is 0 to 5% by weight, preferably 0 to 3% by weight, based on 100% by weight. If the amount used is not more than the upper limit amount, generation of aggregates during the aqueous emulsion polymerization or destruction of the emulsified state, decrease in storage stability of the resulting aqueous dispersion, or pressure-sensitive adhesive layer formed It is preferable because it does not cause inconveniences such as tackiness, deterioration of adhesive strength and water resistance.

The comonomer (a-4) includes the monomers (a-1) to
(a-3) is a comonomer other than the monomer (a-1) to (a-3) copolymerizable, for example, acrylic acid ester other than the (a-1) be able to. Specific examples of such acrylic acid ester include methyl acrylate, i-propyl acrylate, t-butyl acrylate, tridecyl acrylate, stearyl acrylate, and oleyl acrylate (preferably methyl acrylate).

Examples of the comonomer (a-4) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2 -Ethylhexyl methacrylate, i-
Methacrylic acid esters such as decyl methacrylate, lauryl methacrylate, tridecyl methacrylate, cetyl methacrylate, stearyl methacrylate, oleyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate (preferably methyl methacrylate);

For example, vinyl formate, vinyl acetate, vinyl propionate, "vinyl versatate" (trade name)
Saturated fatty acid vinyl ester such as (preferably vinyl acetate); aromatic vinyl monomer such as styrene, α-methylstyrene, vinyltoluene (preferably styrene); and, for example, acrylonitrile, methacrylonitrile (preferably Is acrylonitrile) vinyl cyanide monomer; more selected comonomers can be used as well.

Examples of the comonomer (a-4) include dimethylmalate, di-n-butylmalate, di-2-ethylhexylmalate, di-n-octylmalate, dimethylfumarate, di- A maleic acid or a fumaric acid diester such as n-butyl fumarate, di-2-ethylhexyl fumarate or di-n-octyl fumarate; can also be used.

The amount of the comonomer (a-4) used is generally 0 to 45% by weight based on 100% by weight of the total of the monomers (a-1) to (a-4). %, Preferably 0 to 40% by weight, more preferably 4 to 35% by weight, particularly preferably 9 to 30% by weight. The amount of the comonomer (a-4) used cannot be uniquely determined because it varies depending on the type, but the balance between the adhesive force and the tack and the balance between these and the cohesive force may be determined as desired. Since it is useful for adjustment, the amount within the above range can be appropriately selected to meet such a purpose. When the amount of the comonomer (a-4) used is not more than the upper limit of the above range, inconvenience such as too small tack does not occur, which is preferable. Further, when the amount used is 4% by weight or more, improvement in adhesive strength or cohesive strength can be expected.

The acrylic copolymer used in the present invention is preferably a copolymer of the above-mentioned monomers (a-1) to (a-4) and has a Tg of -40 ° C or lower. It is necessary to be. If Tg is higher than the above temperature and is too high, the tackiness of the pressure-sensitive adhesive layer obtained tends to be insufficient, and
For example, the adhesive strength at a low temperature such as 10 ° C. or lower, particularly the adhesiveness to a nonpolar polymer film such as a polyethylene film or a molded article may be insufficient, which is not preferable.

In the present invention, the glass transition point of the acrylic copolymer is a value measured and determined by the following.

Glass transition point: About 10 mg of a sample of an aqueous dispersion of acrylic copolymer was weighed into a cylindrical cell made of aluminum foil having a thickness of about 0.05 mm and an inner diameter of about 5 mm and a depth of about 5 mm.
A sample dried at 100 ° C. for 2 hours is used as a measurement sample. Seiko Denshi Kogyo SSC-5000 Differential Scanning Calorimeter (Differen
tial scanning calorimeter), and measure from -150 ℃ at a heating rate of 10 ℃ / min.

When measuring the above glass transition point,
The acrylic copolymer is in the form of an acrylic water-based pressure-sensitive adhesive dispersed in an aqueous medium together with a tackifying resin and a surfactant described later, or further contains additives such as pigments and inorganic fillers. In this case, for example, the pressure-sensitive adhesive or its blend is appropriately diluted with ion-exchanged water or the like to reduce the viscosity (for example, about 50 cps or less), and then the rotation speed and rotation time are adjusted to perform centrifugation. By separating these additives with each other, it is possible to separate and collect the aqueous dispersion of the acrylic copolymer and the tackifier used for measuring the glass transition point and the gel content. The reason why such separation is possible is that the specific gravity of the acrylic copolymer used in the present invention is extremely close to 1, which is considerably higher than that of the tackifier or other additives usually used in pressure-sensitive adhesive compositions. Because it is light.

The gel content in the acrylic copolymer used in the present invention is preferably 40% by weight or more,
Particularly preferably, it is 50 to 80% by weight. When the gel content is at least the lower limit value, the cohesive force and the secondary processability are excellent, and when it is at most the upper limit value, the adhesive force and the anchoring property of the pressure-sensitive adhesive layer to the support are obtained. This is preferable because inconveniences such as lacking of water do not occur.

In the present invention, the gel content in the acrylic copolymer is a value obtained by measuring the content of the ethyl acetate insoluble matter in the acrylic copolymer by the following method.

Gel content: (a) Preparation of sample film The thickness of the resulting acrylic copolymer sample film is about 10
Aqueous dispersion of acrylic copolymer was coated on the release material so as to be 0 μm, dried at room temperature for about 1 hour, and then 100
A sample film is prepared by drying at 0 ° C for 2 minutes.

(B) Hot water extraction The sample film of (a) above is cut into about 5 cm × about 15 cm, uniformly wound around a glass rod of about 1.5 cmφ whose weight has been measured in advance, and then weighed to prepare a sample. Obtain the film weight (W ₁ ). The sample film wrapped around this glass rod was placed in a Soxhlet extraction cylindrical filter paper, and a Soxhlet extractor was used to
Hot water extraction is performed at reflux temperature (about 100 ° C) for an hour. The hot water extract weight (w ₁ ) was obtained by heating and drying the obtained hot water extract.
Get.

(C) Extraction with ethyl acetate Similar to the above (b), a sample film wrapped around a glass rod.
The (weight W ₂ ) is extracted with ethyl acetate using a Soxhlet extractor for 4 hours at reflux temperature (about 77 ° C.). The ethyl acetate extract weight (w ₂ ) is obtained by heating and drying the obtained ethyl acetate extract.

(D) Calculation of gel content The gel content is calculated according to the following formula.

[0048]

[Equation 1]

When measuring the above glass transition point,
Acrylic copolymer is in the form of an acrylic water-based pressure-sensitive adhesive dispersed in an aqueous medium together with the tackifying resin and the surfactant as described above, or further an additive such as a pigment or an inorganic filler. When it is blended, it can be measured in the same manner as above, after separating the aqueous dispersion of the acrylic copolymer from the composition by an appropriate separating means such as centrifugation.

Suitable methods for producing the acrylic copolymer used in the present invention include, for example, (a-1) to (a-
The monomer of 4), if necessary in the presence of a water-soluble protective colloid,
A mode in which an appropriate surfactant is used as an emulsifying agent for polymerization and emulsion copolymerization is performed in an aqueous medium can be mentioned.

The above-mentioned surfactant that can be used in the present invention is not particularly limited, and various usual surfactants used in emulsion polymerization can be used, but the pressure-sensitive adhesive obtained can be used. From the viewpoint of good water resistance of the layer, having a radically polymerizable unsaturated group in the molecule,
The use of so-called "reactive emulsifiers" is preferred.

Examples of such reactive emulsifiers include "Eleminol JS-2" and "Eleminol RS-30".
[Above, Sanyo Chemical Industry Co., Ltd.], "Aqualon HS-10
N "," Aqualon HS-20N "[above, Daiichi Kogyo Seiyaku Co., Ltd.
Made], "Adekaria Soap SE-10N" [Asahi Denka Kogyo Co., Ltd.
Made], "Latemuru S-120", "Latemuru S-120A",
Anionic reactive emulsifiers such as "Latemur S-180", "Latemul S-180A" [above, manufactured by Kao Corporation]; for example, "Aqualon RN-20", "Aqualon RN-30", "Aqualon RN-" 50 "(above, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)," Adeka Rear Soap NE-10 "," Adeka Rear Soap NE-20 "," Adeka Rear Soap NE-30 "[Asahi Denka Kogyo Co., Ltd.] , `` RMA-
"564", "RMA-568", "RMA-1114" [above, Nippon Emulsifier
Co., Ltd.] and the like; and the like.

The amount of the reactive emulsifier used is the amount of the monomer
(a-1) to (a-4) for a total of 100 parts by weight, for example, 0.05
The amount may be, for example, about 10 to 10 parts by weight, preferably about 0.1 to 5 parts by weight. If the amount used is at least the lower limit,
It is preferable because the resulting acrylic water-based pressure-sensitive adhesive has good mechanical stability. On the other hand, if the upper limit value or less,
The pressure-sensitive adhesive layer formed is preferable because it has excellent cohesive force and water resistance.

In the emulsion copolymerization, various surfactants such as conventionally known nonionic surfactants and anionic surfactants can be used together with the reactive emulsifier as an emulsifier for polymerization.

Examples of the nonionic surfactants include polyoxyethylene alkyl (or alkenyl) ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether and polyoxyethylene oleyl ether; for example, polyoxyethylene octyl. Polyoxyethylene alkylphenyl ethers such as phenyl ether and polyoxyethylene nonyl phenyl ether; sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monostearate and sorbitan trioleate;

Polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; for example, polyoxyethylene such as polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate Higher fatty acid esters; for example, glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride; for example, polyoxyethylene / polyoxypropylene block copolymer; and the like.

Examples of the anionic surfactants include higher fatty acid salts such as sodium oleate and sodium stearate; alkylaryl sulfonates such as sodium dodecylbenzenesulfonate; sodium lauryl sulfate; Alkyl (or alkenyl) sulfuric acid ester salts such as sodium oleyl sulfate; for example, polyoxyethylene alkyl ether sulfuric acid ester salts such as sodium polyoxyethylene lauryl ether sulfate and ammonium polyexyethylene oleyl ether sulfate;

For example, polyoxyethylene alkylaryl ether sulfate ester salts such as sodium polyoxyethylene nonylphenyl ether sulfate; alkylsulfosuccinate ester salts such as sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate and sodium polyoxyethylene lauryl sulfosuccinate. And derivatives thereof; and the like.

When these surfactants are used as an emulsifying agent for polymerization, it is preferable to use them in an appropriate combination, and the amount used is generally from the monomers (a-1) to (a-
An amount of about 0 to 10 parts by weight can be exemplified with respect to 100 parts by weight in total of 4).

Further, these surfactants are used as an emulsifier for polymerization, and also improve the mechanical stability of the resulting water-based pressure-sensitive adhesive and can be applied to a release material (paper or plastic film release-treated with a silicone resin or the like). It is often added after the aqueous emulsion copolymerization for the purpose of improving coatability. For example, a transfer method (the pressure-sensitive adhesive is applied on a release material and dried to form a pressure-sensitive adhesive layer, and then the base material is overlaid and pressed on the pressure-sensitive adhesive layer, When the method of transferring the pressure-sensitive adhesive layer) is adopted, the sulfosuccinate salt-based anionic surfactant exemplified in the anionic surfactant is often used.

The preferred method for producing the acrylic copolymer aqueous dispersion preferably used in the present invention is, for example, as described above.
Emulsifying the monomers (a-1) to (a-4) in a water-based medium in the presence of a water-soluble protective colloid such as polyvinyl alcohol using the above-mentioned surfactant as an emulsifier for polymerization. Copolymerization is preferred.

Examples of the above water-soluble protective colloids include polyvinyl alcohols such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol and modified polyvinyl alcohol (hereinafter sometimes abbreviated as PVA).
Classes; for example, cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose salt; and natural polysaccharides such as guar gum;
And the like, and these may be used alone or in combination of plural kinds.

Among these water-soluble protective colloids, PVAs are preferably used from the viewpoints of ease of emulsion copolymerization, excellent cohesive force of the pressure-sensitive adhesive layer to be obtained, and partially saponified PVA. And / or modified PVA having an average degree of polymerization of 50
It is particularly preferable to use one of 0 or less. The amount of the water-soluble protective colloid used is about 0 to 2 parts by weight based on 100 parts by weight of the total of the monomers (a-1) to (a-4).

Further, in emulsion copolymerization, for example, persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate; organic compounds such as t-butyl hydroperoxide, cumene hydroperoxide and p-menthane hydroperoxide Polymerization initiators such as peroxides and hydrogen peroxide can be used. These can be used either in one kind or in a combination of plural kinds. It is preferable to use these polymerization initiators in an amount of about 0.1 to 1 part by weight based on 100 parts by weight of the total of the monomers (a-1) to (a-4).

In the aqueous emulsion copolymerization, a reducing agent can be used if desired. For example,
Examples thereof include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate metal salt; and reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite. These reducing agents are the monomers (a-1)
It is preferable to use about 0.1 to 1 part by weight per 100 parts by weight of (a-4).

Furthermore, in the case of aqueous emulsion copolymerization, a chain transfer agent can be used to obtain a copolymer having the above weight average molecular weight range. Examples of such a chain transfer agent include n-dodecyl. Examples thereof include mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, 2-ethylhexyl thioglycolate, 2-mercaptoethanol and trichlorobromomethane. These chain transfer agents are preferably used in an amount of about 0 to 1 part by weight based on 100 parts by weight of the total of the monomers (a-1) to (a-4).

The copolymerization temperature suitably adopted in the emulsion copolymerization of the acrylic copolymer used in the present invention is about 40 to
100 ° C., especially about 60-90 ° C.

The average particle diameter of the dispersed particles of the acrylic copolymer thus obtained in the aqueous medium is preferably more than 0.3 μm, more preferably 0.35 to 2 μm, and particularly preferably 0.4 to 1 μm. Is good. If the average particle diameter is not less than the lower limit, the cohesive force of the pressure-sensitive adhesive layer obtained is insufficient, and the stability and secondary processability of the obtained pressure-sensitive adhesive sheet are deteriorated. Is not generated, which is preferable. On the other hand, when it is at most the upper limit value, the film-forming property at the time of forming the pressure-sensitive adhesive layer is excellent, and undesired aggregates are hardly generated in the production of the aqueous dispersion, which is preferable.

In the present specification, the average particle size of dispersed particles is defined as “New Experimental Chemistry Course 4 Basic Technology 3” edited by the Chemical Society of Japan.
Light (II) ", pages 725 to 741 (published on Mar. 20, 1976, Maruzen Co., Ltd.) by a dynamic light scattering method (hereinafter sometimes referred to as DLS method). Specifically, it is a value measured and determined by the method described below.

Average particle diameter: An aqueous dispersion of a copolymer or the like is diluted with distilled water 50,000 to 150,000 times, and after sufficiently stirring and mixing,
About 10 using a Pasteur pipette in a 21 mmφ glass cell
ml, and set it at the predetermined position of the dynamic light scattering photometer "DLS-700" (manufactured by Otsuka Electronics Co., Ltd.), measured under the following measurement conditions, and processed the measurement results by computer processing. Calculate the average particle size.

[Measurement conditions] Measurement temperature 25 ± 1 ° C Clock rate 10 μsec Correlation channel (Corelation Channel) 512 Total number of measurements 200 pieces Light scattering angle 90 °

In the above measurement of the average particle diameter, the acrylic copolymer is in the form of an acrylic water-based pressure-sensitive adhesive, which is dispersed in an aqueous medium together with the tackifying resin and the surfactant as described above. Or, when an additive such as a pigment or an inorganic filler is further mixed, the measurement is performed after separating the aqueous dispersion of the acrylic copolymer from the composition by an appropriate separation means such as centrifugation as described above. can do.

The aqueous dispersion of the acrylic copolymer which can be obtained as described above can be adjusted in pH with ammonia water or the like, if necessary. Such a dispersion has a solid content concentration of 30 to 70% by weight, preferably 45 to 65% by weight, and a viscosity of 50.
˜3000 cps (BH type rotational viscometer, 25 ° C., 20 rpm; viscosity measurement conditions are the same below), and pH is preferably about 2-8.

The acrylic water-based pressure-sensitive adhesive of the present invention comprises the above-mentioned acrylic copolymer as a copolymer component.
A tackifying resin (B) is contained as an essential component together with (A).

Examples of the tackifying resin (B) include coumarone indene resin, terpene resin, terpene resin.
Phenol resin, rosin resin, pt-butylphenol
Acetylene resin, phenol-formaldehyde resin,
Xylene / formaldehyde resin, petroleum-based hydrocarbon resin, hydrogenated hydrocarbon resin, turpentine-based resin, etc. can be used. From the viewpoint of low-temperature adhesive strength and curved surface adhesiveness, etc., rosin resin, petroleum-based hydrocarbon resin Is preferably used.

The tackifying resin (B) used in the present invention needs to have a softening point of 70 to 180 ° C, preferably 100 to 160 ° C, particularly preferably 120 to 150 ° C. If the softening point of the tackifying resin (B) is too low below the lower limit, it is not preferable because the cohesive force of the pressure-sensitive adhesive layer obtained tends to decrease, while it is too high above the upper limit. Is not preferable because the low temperature adhesive strength tends to be insufficiently improved. The softening point of the tackifying resin is a value measured according to the ring and ball method of JIS K-2531.

The tackifying resin that can be preferably used in the present invention needs to have a weight average molecular weight (hereinafter sometimes abbreviated as Mw) of 5000 or less, particularly 2000 to 4000. If the value of Mw exceeds the upper limit and is too large, the adhesive properties such as normal-state adhesive strength, low-temperature adhesive strength, and curved surface adhesiveness of the obtained pressure-sensitive adhesive layer tend to be deteriorated, which is not preferable. On the other hand, if it is at least the lower limit value, it is preferable because there will be no inconvenience such as reduction in cohesive force of the obtained pressure-sensitive adhesive layer. The Mw of the tackifying resin in the present invention is a polystyrene-equivalent value measured by the GPC method.

The average particle size of the dispersed particles of the tackifying resin (B) used in the present invention in the aqueous medium is preferably 0.3 μm or less, and preferably 0.05 to 0.28 μm. If the average particle diameter is not more than the upper limit, the pressure-sensitive adhesive layer obtained will have insufficient adhesive strength, and the pressure-sensitive adhesive sheet obtained will have inferior stability and secondary processability. Is less likely to occur, which is preferable. On the other hand, it is preferably at least the lower limit value because it is easily available as a commercial product.

In the present invention, the average particle size of the dispersed particles of the tackifying resin in the aqueous medium is the value obtained by the same measurement as in the acrylic copolymer.

Further, in measuring the Mw and the average particle size, the form of an acrylic water-based pressure-sensitive adhesive in which an acrylic copolymer is dispersed in an aqueous medium together with the tackifying resin and the surfactant as described above. Or when an additive such as a pigment or an inorganic filler is further blended, an aqueous dispersion of an acrylic copolymer is separated from the composition by an appropriate separation means such as centrifugation as described above. Can be measured from.

Examples of such a tackifying resin (B) include "Super Ester E-625A", "Super Ester E-635", "Super Ester E-650" (made by Arakawa Chemical Industries, Ltd.). , "Hariester SK-130D", "Hariester SK-508" (all manufactured by Harima Kasei Co., Ltd.); rosin resins such as "QME-100", "QME-125ps", "QME-"
Commercially available products under the trade names of petroleum hydrocarbon resins such as 800 "(all manufactured by Toho Chemical Industry Co., Ltd.) are preferably used.

The acrylic water-based pressure-sensitive adhesive of the present invention contains, as a copolymer component, the above-mentioned acrylic copolymer (A) 70-98.
% By weight, preferably 75 to 96% by weight, and 2 to 30% by weight of the tackifying resin (B), preferably 4 to 25% by weight, provided that the total of (A) and (B) is 100% by weight. It is]. If the blending amount of the tackifying resin (B) exceeds the upper limit and is too large, the tack of the pressure-sensitive adhesive layer to be obtained tends to be insufficient, the low-temperature adhesive strength decreases, and the cohesive strength and water resistance also decrease. It is not preferable because it is often done. On the other hand, if the blending amount of the copolymer component (B) is too small as less than the above lower limit, the adhesive force of the obtained pressure-sensitive adhesive layer to the nonpolar polymer may be insufficient, or the secondary processability may be poor. It tends to get worse, which is not preferable.

The acrylic water-based pressure-sensitive adhesive of the present invention is the above-mentioned acrylic copolymer from the viewpoint of ease of production and the like.
It is preferable to prepare (A) and the tackifying resin (B) by mixing them in the form of an aqueous dispersion, and adding / blending an appropriate blend to the mixture, if necessary.

The acrylic water-based pressure-sensitive adhesive of the present invention thus obtained generally has a solid content of 30 to 70% by weight and a viscosity of
100 ~ 15000cps, pH 3 ~ 8 is good, and when used in transfer method, solid content concentration 30 ~ 70wt%, viscosity 3000 ~
15000 cps and pH 4-8.5 are suitable.

In the acrylic water-based pressure-sensitive adhesive of the present invention, the light transmittance of the film formed from it is required to be 77 to 88%. If the transmittance is too small, below the lower limit, the adhesive force of the obtained pressure-sensitive adhesive layer to the nonpolar polymer tends to be insufficient, resulting in poor low-temperature adhesive force, curved surface adhesiveness and secondary processability. It tends to become unfavorable. On the other hand, if it exceeds the upper limit and is too large, the adhesive force to the non-polar polymer tends to be insufficient, and the curved surface adhesiveness and the secondary workability tend to be deteriorated, which is not preferable.

In the present invention, when a petroleum hydrocarbon resin is used as the suitable tackifying resin (B) as described above, the light transmittance of the film formed from the resulting water-based pressure-sensitive adhesive is 79 to 87% is preferable, and when a rosin resin is used as the tackifying resin (B), the light transmittance of the film formed from the resulting water-based pressure-sensitive adhesive is 83 to 87%. Is preferred. The light transmittance of the water-based pressure-sensitive adhesive film is measured by the following method.

Measurement of light transmittance: (a) Preparation of water-based pressure-sensitive adhesive film sample A water-based pressure-sensitive adhesive sample was placed on a release material so that the film thickness after drying was 20 ± 1 μm. Apply using a doctor blade and dry at 100 ° C. for 5 minutes with a hot air circulation dryer. This film is transferred to a micro slide glass [Matsunami Glass Industry Co., Ltd .; thickness 0.8 to 1.0 mm] to obtain a sample piece.

(B) Measurement of Film Light Transmittance Before the measurement of the sample piece prepared in the item (a), the haze meter "TC-HIIID" was used.
P ”(manufactured by Tokyo Denshoku Co., Ltd.) is measured under the following conditions, and the light transmittance is calculated by the following formula. Measurement method: integrating sphere method JIS K-7105 Light source: halogen lamp 12V, 50W, 2000Hz Measurement diameter: 10mmφ Detection element: Silicon photocell Measurement condition: C light

[0089]

[Equation 2]

Further, the elongation of the film formed from the acrylic water-based pressure-sensitive adhesive of the present invention is preferably 2100% or less, and particularly preferably 1200 to 2000%. If the film elongation is less than or equal to the upper limit, the resulting pressure-sensitive adhesive sheet has excellent secondary processability, which is preferable. If the film elongation is at least the lower limit, the normal adhesive strength and low temperature of the obtained pressure-sensitive adhesive sheet are preferable. It is preferable because it has excellent adhesive strength.

The elongation of the acrylic water-based pressure-sensitive adhesive film is a value measured by the following method.

Film elongation: A water-based pressure-sensitive adhesive sample was placed on a release material, and the film thickness after drying was 100 ± 10 μm.
It is applied using a doctor blade so that it becomes, and left to stand at 25 ° C. for about 30 minutes to be semi-dried, and then dried at 100 ° C. for 10 minutes by a hot air circulation dryer. On the surface of the created film
Cellophane tape is attached in parallel in two rows with a space of 10 mm to reinforce the film, and the cellophane tape is cut at 10 mm intervals in a direction perpendicular to the longitudinal direction to obtain a test piece. The tensile test is performed using a self-testing tensile tester in a constant temperature and humidity room at 23 ° C and 65% RH.

The test piece had its cellophane tape adhered portion fixed with a knob jig, and was subjected to a tensile test.
It is installed in the vertical direction with no stress at intervals of mm and is pulled at a pulling speed of 100 mm / min until the film is cut. The elongation at break is read from the automatic recording paper and the film elongation is calculated according to the following formula. The numerical value is the average value of the results of five test pieces.

Film elongation = {Length at break (cm) -1} × 100 (%)

As a method for forming a pressure-sensitive adhesive layer using the acrylic water-based pressure-sensitive adhesive of the present invention, the pressure-sensitive adhesive is directly coated on a substrate such as paper or plastic film and dried. The direct method can be adopted. In addition, a transfer method, that is, a pressure-sensitive adhesive layer is formed by coating the pressure-sensitive adhesive on a release material such as paper or plastic film release-treated with a silicone resin and drying the pressure-sensitive adhesive layer. A method of stacking the base material on the adhesive layer and applying pressure to transfer the pressure-sensitive adhesive layer onto the base material can also be used.

In the above transfer method, the pressure-sensitive adhesive of the present invention is usually thickened and used with various thickeners. Examples of such a thickener include sodium polyacrylate and the PVA.
Examples thereof include the above-mentioned cellulose derivatives, aqueous dispersion-type poly (meth) acrylic acid-based copolymer thickeners that are thickened by alkali, and the like. The amount of these thickeners can be appropriately determined depending on the desired viscosity, and 0 to 10 parts by weight as a solid content relative to 100 parts by weight of the acrylic copolymer,
It is preferably in the range of 0 to 5 parts by weight.

The water-based pressure-sensitive adhesive of the present invention may be used by adding various modifying resins such as synthetic rubber, natural rubber, ethylene-vinyl acetate copolymer resin, etc., as long as the desired performance is not impaired. You can

The addition amount of these various modifying resins can be appropriately selected from the viewpoint of the balance between the adhesive force to the nonpolar polymer and the cohesive force, and the total amount of the copolymer components (A) and (B) is 100 parts by weight. On the other hand, for example, 0 to 60 parts by weight, preferably 0 to
An example of the added amount is 30 parts by weight.

Further, if necessary, a plasticizer, a wetting agent, a coloring agent, an inorganic filler, a stabilizer, a defoaming agent, an antiseptic, an antifungal agent, etc. are added to the pressure-sensitive adhesive of the present invention. It can also be used.

[0100]

EXAMPLES The present invention will be described in more detail with reference to Examples along with Comparative Examples and Reference Examples. It should be noted that preparation of a pressure-sensitive adhesive sheet for testing, and various types of pressure-sensitive adhesive sheet such as normal-state adhesive strength, tack, cohesive strength, low-temperature adhesive strength, curved surface adhesiveness, water-resistant adhesiveness, cutting property and adhesive force aging rate The physical property measuring methods are as follows.

(1) Preparation of Pressure-Sensitive Adhesive Sheet for Test A pressure- sensitive adhesive sample was applied on a release material so that the pressure-sensitive adhesive layer after drying would be 20 ± 3 g / m ² , and 100 Dry at 90 ° C for 90 seconds in a hot air circulation dryer, and then transfer to high-quality paper <55> to create a pressure-sensitive adhesive sheet.

(2) Measurement of adhesive strength SUS 30 polished with # 280 water resistant abrasive paper specified in JIS R-6253
4 stainless steel plate (hereinafter sometimes abbreviated as SUS)
And polyethylene plate (hereinafter sometimes abbreviated as PE plate) (surface tension γ ₀ = 33 dyn by the method specified in JIS K-6768).
/ Cm), the test piece cut out from the test pressure-sensitive adhesive sheet prepared in (1) above is pressure bonded according to the method of JIS Z-0237, and after 24 hours, 23 ° C, 65% RH, peeling speed The peel strength (g / 25 mm) is measured under the condition of 300 mm / min.

(3) Tack measurement According to the J. Dow method, a test piece (100 mm in length) cut out from the pressure-sensitive adhesive sheet for test prepared in (1) above on a slope with an inclination angle of 30 °.
Affixed, and the diameter x from the position 100 mm above the slope of the test piece
Roll a / 32 inch size steel ball and mark it with the size x of the largest diameter ball that will stop on the sample.

(4) Measurement of cohesive force A test piece cut out from the test pressure-sensitive adhesive sheet prepared in (1) above was applied to a SUS plate treated in the same manner as in (2) above, and the adhesion area was 25 Stick it so that it becomes × 25 mm ² , and press it back and forth once with a 2 kg roller. Place a static load of 1 kg on the sample in an atmosphere of 40 ° C x 30% RH and measure the time until the load falls.

(5) Low-temperature adhesive strength A test piece cut out from the pressure-sensitive adhesive sheet prepared in the previous (1) and a PE plate similar to that used in the previous (2) were placed in a thermostatic chamber at 0 ° C.
After standing for 4 hours or more, pressure bonding is performed at 0 ° C. according to the method of JIS Z-0237, and after standing at 0 ° C. for 20 minutes, the peeling strength (g / 25 mm) is measured under the conditions of 0 ° C. and peeling speed of 300 mm / min.

(6) Curved surface adhesiveness A test piece of 10 × 20 mm ² was cut out from the pressure-sensitive adhesive sheet prepared in the above (1), and a polyethylene rod of φ = 10 mm [PE plate used in the above (2)] The same material as above], 23 ℃, 65
After standing for 24 hours under the condition of% RH, observe how the test piece floats from the rod.

○: No floating △: Slight floating ×: Complete lifting

(7) Water-Resistant Adhesion Property The polyethylene rod prepared in the previous section (6), to which the test piece was attached, was immersed in water immediately after the attachment to prevent the test piece from floating from the polyethylene rod. The condition is measured 30 minutes after immersion.

○: No floating △: Slight floating ×: Complete lifting

(8) Cutting property A test piece 1 having a width of 5 cm from the pressure-sensitive adhesive sheet prepared in the above (1)
Cut out 00 sheets and observe the state of blade contamination when cutting 10 times with a cutting machine.

◯: No stains Δ: Slight stains ×: Great stains

(9) Adhesive strength aging stability test The pressure-sensitive adhesive sheet prepared in (1) above was left at 50 ° C. and 95% RH for 5 days, and then adhered to a PE plate according to the method in (2) above. The adhesive force is measured, and the rate of change of the adhesive force is measured with the adhesive force before standing as 100%.

Reference Example 1 70 parts by weight of ion-exchanged water, 0.04 parts by weight of ammonium persulfate (APS) as a polymerization initiator and meta as a reducing agent were placed in a reactor equipped with a thermometer, a stirrer, a nitrogen introducing tube and a reflux condenser. Charge 0.04 parts by weight of sodium bisulfite (SMBS),
The internal temperature was raised to 80 ° C.

On the other hand, in another container, 30 parts by weight of ion-exchanged water and "Aqualon HS-10" [α-sulfo-ω] as an emulsifier were used.
-[2- (1-propenyl) -4-nonylphenoxy] polyoxyethylene (n = 10) ammonium salt; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.]
0.5 parts by weight, 1.0 parts by weight of polyoxyethylene alkylphenyl ether type nonionic surfactant (HLB = about 9) and 0.2 parts by weight of partially saponified PVA (polymerization degree 300) were charged and dissolved with stirring. -A monomer mixture of 84 parts by weight of ethylhexyl acrylate (EHA), 15 parts by weight of methyl methacrylate (MMA) and 1 part by weight of acrylic acid (AA) was added and stirred to obtain a monomer premix.

The contents of the reactor were stirred under a nitrogen stream, and while maintaining the temperature of the contents at 80 ° C., the above monomer premix and 4% by weight APS aqueous solution were sequentially added to initiate polymerization, and the reaction was conducted to about 2 The polymerization reaction was carried out for a time. After completion of the polymerization reaction, stirring was continued at the same temperature for about 1 hour and then cooled, and the pH was adjusted with aqueous ammonia to obtain an aqueous dispersion of an acrylic copolymer.

The characteristics of this dispersion are as follows: solid content 50.3% by weight,
The pH was 5.8, the viscosity was 100 cps, and the average particle size was about 0.91 μm. The characteristic values of this acrylic copolymer were a glass transition point of -53 ° C and a gel content of 62% by weight.

Reference Example 2 In Reference Example 1, as the emulsifier, "Aqualon HS-10"
Instead of using 0.5 parts by weight and 1.0 parts by weight of polyoxyethylene alkylphenyl ether type nonionic surfactant (HLB = about 9), "Trax H-45W" [polyoxyethylene (n = 4.5) alkylphenyl ether sulfate ester Salt type anionic surfactant, solid content about 30% by weight; manufactured by NOF CORPORATION, 0.5 part by weight (solid content about 0.15 part by weight) and polyoxyethylene alkylphenyl ether type nonionic surfactant (HLB = about 9) An aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Reference Example 1 except that 1.0 part by weight was used and the amount of ion-exchanged water for the monomer premix was adjusted. Table 1 shows the monomer composition and characteristic values of the acrylic copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example 3 Instead of using 15 parts by weight of MMA in Reference Example 1, MMA was used.
An aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Reference Example 1 except that 5 parts by weight and 10 parts by weight of vinyl acetate (VAc) were used. Table 1 shows the monomer composition and characteristic values of the acrylic copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example 4 In Reference Example 1, 84 parts by weight of EHA, 15 parts by weight of MMA and AA were used.
Instead of using 1 part by weight, EHA 70 parts by weight, butyl acrylate (BA) 10 parts by weight, methacrylic acid (MAA) 1 part by weight, acrylamide (AMD) 0.5 parts by weight, MMA 10 parts by weight and VAc 8.5 parts by weight are used. An aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Reference Example 1. Table 1 shows the monomer composition and characteristic values of the acrylic copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example 5 The same procedure as in Reference Example 1 except that EHA (59 parts by weight) and MMA (40 parts by weight) were used instead of EHA (84 parts by weight) and MMA (15 parts by weight) in Reference Example 1, was used. A dispersion was obtained. Table 1 shows the monomer composition and characteristic values of the acrylic copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example 6 In Reference Example 1, 0.1 part by weight of "Aqualon HS-10" was added as an initial addition emulsifier into the reactor, and the amount of "Aqualon HS-10" used for monomer premix was adjusted to 0.4. An aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Reference Example 1 except that the weight part was used. Table 1 shows the monomer composition and characteristic values of the acrylic copolymer, and the characteristics of the aqueous dispersion thereof.

[0122]

[Table 1]

Example 1 169 parts by weight of the aqueous dispersion of Reference Example 1 (about 85 parts by weight of an acrylic copolymer) was added to an aqueous dispersion of tackifying resin [“QME-12
5ps "(trade name); petroleum-based hydrocarbon resin, solid content about 50% by weight, softening point 125 ° C, Mw2800, average particle size 0.27 μm; manufactured by Toho Chemical Industry Co., Ltd.] 30 parts by weight (petroleum-based hydrocarbon resin About 15
5 parts by weight of sodium dioctyl sulfosuccinate-type anionic surfactant having a solid content of 40% by weight, and then an alkali thickener and aqueous ammonia are added to the mixture to give an aqueous feel of pH 7.1, about 5020 cps. A pressure-sensitive adhesive was obtained. The pressure-sensitive adhesive layer from this pressure-sensitive adhesive had a light transmittance of 84.5% according to the above-mentioned test method and a film elongation of 14%.
80%.

Using this pressure-sensitive adhesive, a pressure-sensitive adhesive sheet for testing was prepared according to the method of (1) above, and the physical properties of the pressure-sensitive adhesive sheet were measured according to various physical property measuring methods (2) to (9). went. Table 2 shows the composition and characteristic values of the water-based pressure-sensitive adhesive, and Table 3 shows various physical properties of the pressure-sensitive adhesive sheet.

Examples 2-3 and Comparative Examples 1-2 In Example 1, the use ratio of the dispersion of Reference Example 1 and the aqueous dispersion of tackifying resin ("QME-125ps") was changed, or Acrylic water-based pressure-sensitive adhesive was obtained in the same manner as in Example 1 except that only the dispersion of No. 1 was used and the aqueous dispersion of tackifier resin was not used. The physical properties of the pressure sensitive adhesive sheet were measured. Table 2 shows the composition of the water-based pressure-sensitive adhesive, the type of the tackifying resin used and its characteristic values, and the characteristic values of the resulting water-based pressure-sensitive adhesive, and Table 3 shows the physical properties of the pressure-sensitive adhesive sheet. .

Examples 4 to 7 and Comparative Example 3 In Example 1, the dispersion liquid of Reference Example 1 was used as a solid content.
An acrylic water-based pressure-sensitive adhesive was obtained in the same manner as in Example 1 except that 85 parts by weight of the dispersions of Reference Examples 1 to 6 were used as solids instead of using parts by weight. Was prepared and the physical properties of the pressure-sensitive adhesive sheet were measured. Table 2 shows the composition of the water-based pressure-sensitive adhesive, the type of the tackifying resin used and its characteristic values, and the characteristic values of the resulting water-based pressure-sensitive adhesive, and Table 3 shows the physical properties of the pressure-sensitive adhesive sheet. .

Examples 8 to 10 and Comparative Examples 4 to 6 In Example 1, 15 wt.% Of the petroleum hydrocarbon resin aqueous dispersion “QME-125ps” was used as the tackifier resin aqueous dispersion liquid. Instead of using parts, "QME-100" and "QME-6" which are aqueous dispersions of petroleum hydrocarbon resins.
0 "[above Toho Chemical Industry Co., Ltd.]," FTR-6125 "[Mitsui Petrochemical Co., Ltd.] or an aqueous dispersion of rosin resin" Hariester SK-90D "," Hariester SK- " 508 "
[Made by Harima Chemicals Co., Ltd.], “Super Ester E-625
A "(manufactured by Arakawa Chemical Industry Co., Ltd.) was used to obtain an acrylic water-based pressure-sensitive adhesive in the same manner as in Example 1 except that 15 parts by weight was used as the tackifying resin. A sheet was prepared and the physical properties of the pressure-sensitive adhesive sheet were measured. Table 2 shows the compounding composition of the water-based pressure-sensitive adhesive, the kind of the tackifying resin used and its characteristic value, and the characteristic value of the obtained water-based pressure-sensitive adhesive, and Table 3 shows the physical properties of the pressure-sensitive adhesive sheet. .

[0128]

[Table 2]

[0129]

[Table 3]

[0130]

The acrylic water-based pressure-sensitive adhesive of the present invention comprises
An acrylic water-based pressure-sensitive adhesive obtained by blending an acrylic copolymer having a specific glass transition point, and a tackifying resin having a specific softening point and a specific average molecular weight in specific amounts. The acrylic water-based pressure-sensitive adhesive has a light transmittance of a film formed from the pressure-sensitive adhesive in a specific range.

The water-based pressure-sensitive adhesive of the present invention is effective for forming a pressure-sensitive adhesive layer in applications such as pressure-sensitive adhesive tapes, films and labels, and has excellent adhesive strength, tackiness and excellent cohesive strength. In addition, it has excellent adhesion to non-polar polymer films such as polyolefin or molded products, especially excellent curved surface adhesion and low-temperature adhesion, as well as secondary processability such as slitting, cutting and punching. It is also excellent.

If the blending ratio of the acrylic copolymer and the tackifying resin in the water-based pressure sensitive adhesive deviates from the scope of the present invention and the blending amount of the tackifying resin is too large, the resulting pressure sensitive adhesive will be obtained. The tack of the layer tends to be insufficient, and the cohesive strength, low temperature adhesive strength, and water resistant adhesiveness are often reduced. On the other hand, if the amount of the tackifying resin compounded is too small, the resulting pressure-sensitive adhesive layer tends to have insufficient adhesion to the nonpolar polymer, or the secondary processability tends to deteriorate.

Further, if the light transmittance of the film formed from the water-based pressure-sensitive adhesive is too small outside the specific range of the present invention, the adhesive force of the obtained pressure-sensitive adhesive layer to the non-polar polymer is insufficient. It tends to be sufficient, the low temperature adhesive strength, curved surface adhesiveness and secondary processability tend to be poor, and when it is too large, the adhesive strength to a non-polar polymer tends to be insufficient, resulting in curved surface adhesiveness and Subsequent workability tends to deteriorate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunichi Yakita 53 Yoneyama Minamimachi, Sano City, Tochigi Prefecture Nippon Carbide Industry Co., Ltd. Sano Dormitory

Claims (8)

[Claims] 1. A total of 100% by weight of the following (A) and (B): (A)
Acrylic copolymer having a glass transition temperature of -40 ° C or lower
70 to 98% by weight, and (B) a tackifying resin having a softening point of 70 to 180 ° C. and a weight average molecular weight of 5000 or less 2
30% by weight is an acrylic aqueous pressure-sensitive adhesive which is dispersed in an aqueous medium, wherein the light transmittance of a film formed from the pressure-sensitive adhesive is 77 to 88%. Acrylic water-based pressure sensitive adhesive. 2. An acrylic copolymer (A) is a monomer (a-1) shown below.
~ (A-4), (a-1) represented by the following general formula, the glass transition point of the homopolymer acrylate ester -20 ℃ or less 50-99.9
% By weight, CH ₂ ═CH—COOR ¹ (wherein R ¹ represents a linear or branched alkyl group having 2 to 12 carbon atoms) (a-2) α, β-unsaturation having 3 to 5 carbon atoms 0.1 to 5% by weight of mono- or di-carboxylic acid, (a-3) a monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule, Monomers other than the monomers (b) and (c) 0 to 5% by weight, and (a-4) the monomers copolymerizable with the above monomers (a-1) to (a-3), The acrylic water-based pressure-sensitive adhesive according to claim 1, which is an acrylic copolymer obtained by emulsion copolymerizing 0 to 45% by weight of a comonomer other than the monomers (a-1) to (a-3). Agent. 3. The acrylic water-based pressure-sensitive adhesive according to claim 1, wherein the average particle size of the dispersed particles of the acrylic copolymer in the aqueous medium exceeds 0.3 μm. 4. The acrylic aqueous pressure-sensitive adhesive according to claim 1, wherein the tackifying resin is dispersed in an aqueous medium. 5. The acrylic aqueous pressure-sensitive adhesive according to claim 1, wherein the tackifying resin is dispersed in an aqueous medium. 6. The acrylic water-based pressure-sensitive adhesive according to claim 1, wherein the average particle diameter of dispersed particles of the tackifying resin in the aqueous medium is 0.3 μm or less. 7. The acrylic water-based pressure-sensitive adhesive according to claim 1, wherein the tackifying resin is a petroleum hydrocarbon resin. 8. The acrylic water-based pressure-sensitive adhesive according to claim 1, wherein the film formed from the acrylic water-based pressure-sensitive adhesive has an elongation of 2100% or less.