JP3335463B2 - Acrylic water-based pressure-sensitive adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film or molded article of a nonpolar polymer such as polyolefin, which has excellent adhesive strength, particularly excellent curved surface adhesion and low-temperature adhesion, as well as slitting and cutting. The present invention relates to an acrylic water-based pressure-sensitive adhesive composition that is also excellent in secondary workability such as punching and the like, specifically, an acrylic copolymer having a specific glass transition point, and a specific composition and a specific glass transition point. Acrylic water-based pressure-sensitive adhesive composition comprising a specific amount of an α-olefin-saturated fatty acid vinyl ester copolymer having the following formula, wherein the acrylic copolymer dispersed in the composition and α The present invention relates to an acrylic water-based pressure-sensitive adhesive composition in which the average particle size of the olefin-saturated fatty acid vinyl ester copolymer is in a specific range.

[0002]

2. Description of the Related Art Pressure-sensitive adhesives are used for tapes, labels,
It covers a wide range of areas such as stickers and wallpapers, and the material of the non-adhesive is plastic, metal, glass, ceramics, paper,
It covers a wide area such as cloth, wood, and fresh food.

Hitherto, natural rubbers, synthetic rubbers, solvent-based acrylic copolymers, aqueous dispersion-type acrylic copolymers, and the like have been used as main raw materials for pressure-sensitive adhesives. Among these, pressure-sensitive adhesives based on aqueous dispersion-type acrylic copolymers do not contain organic solvents and do not cause fires or environmental health problems. It has become.

[0004] However, the pressure-sensitive adhesive containing an aqueous dispersion-type acrylic copolymer as a main raw material has a higher water resistance and adhesive strength than the pressure-sensitive adhesive containing a solvent-type acrylic copolymer as a main raw material. In particular, there has been a problem that the adhesive strength to a film or molded article of a nonpolar polymer such as polyolefin tends to be insufficient.

As a typical attempt to improve the above-mentioned problems of the pressure-sensitive adhesive containing an aqueous dispersion type acrylic copolymer as a main raw material, for example, Japanese Patent Application Laid-Open No. 58-79068 discloses a pressure-sensitive adhesive. 100 parts by weight of an acrylic emulsion for an agent, 5 to 30% by weight of ethylene, 20 to 90% by weight of vinyl acetate, and an alkyl (meth) acrylate 5 having an alkyl moiety having 1 to 12 carbon atoms.
An aqueous dispersion-type acrylic pressure-sensitive adhesive containing 5 to 35 parts by weight of an ethylene / vinyl acetate / acrylic copolymer emulsion obtained by copolymerization of from 50 to 50% by weight is disclosed. This pressure-sensitive adhesive can improve the adhesive strength of a non-polar polymer such as polyolefin to an object to be adhered by blending a specific amount of the above-mentioned ethylene / vinyl acetate / acrylic copolymer emulsion with a conventional acrylic emulsion. It is to be improved.

However, the pressure-sensitive adhesive proposed above does improve the adhesive strength of the non-polar polymer to the adherend. For example, in the pressure-sensitive adhesive described in the examples of the proposal, for example, Low-temperature adhesive and non-polar polymers required for attaching various labels to packaged foods in a freezer, etc., for example, into a rod-shaped molded product with a small diameter of about 10 to 20 mmφ or a molded product with an edge portion There is a problem that the curved surface of the molded article is not sufficient, and the average particle diameter of the acrylic copolymer to be blended is too small,
When the average particle size of the ethylene / vinyl acetate / acrylic copolymer is too large, it is clear that the cohesive force of the pressure-sensitive adhesive and the secondary processing properties such as slitting, cutting and punching become insufficient. It has become.

[0007]

SUMMARY OF THE INVENTION The present inventors have found that while maintaining the essential properties of a pressure-sensitive adhesive, that is, tack, state adhesive strength, cohesive strength, and storage stability in a well-balanced manner, non-polar polymer As a result of repeated studies to obtain an acrylic water-based pressure-sensitive adhesive composition with excellent adhesion to films and molded products, especially excellent curved surface adhesion and low-temperature adhesion, it has a specific glass transition point. A specific amount of an aqueous dispersion of an α-olefin-saturated fatty acid vinyl ester copolymer having a specific composition, a specific glass transition point, and a specific average particle size is mixed with an aqueous acrylic copolymer dispersion having an average particle size range. The resulting composition is an excellent acrylic water-based pressure-sensitive adhesive composition that solves all of the above problems, among them, among those compositions, the elongation of the resulting film is not more than a specific value The was completed particular onsets viewed such that the secondary workability is excellent, the present invention.

[0008]

According to the present invention, there are provided the following copolymer components (A) and (B):

(A) 60 to 98% by weight of an acrylic copolymer having a glass transition point of -40 ° C. or lower;

(B) The following monomers (b-1) to (b-5) (provided that (b-
1) to (b-5) as 100% by weight],

(B-1) 5 to 40% by weight of an α-olefin represented by the following general formula (1), CH ₂ ＣＨCH—R ¹ ‥‥‥ (1) wherein R ¹ is hydrogen or carbon number Shows a linear or branched alkyl group of 12 or less]

(B-2) 62 to 90% of a saturated fatty acid vinyl ester represented by the following general formula (2): CH ₂ ＣＨCH—OCOR ² (2) wherein R ² is hydrogen Or a linear or branched alkyl group having 1 to 18 carbon atoms)

(B-3) 0 to 5% by weight of an α, β-unsaturated mono- or dicarboxylic acid having 3 to 5 carbon atoms,

(B-4) A monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule, and a monomer other than the above (b-3) ~ 5% by weight, and

(B-5) Comonomers copolymerizable with the monomers (b-1) to (b-4) and other than the monomers (b-1) to (b-4) 0-10
weight%,

An α-olefin saturated fatty acid vinyl ester-based copolymer obtained by copolymerizing the α-olefin saturated fatty acid vinyl ester-based copolymer having a glass transition point of −10 ° C. to −30 ° C., α-olefin saturated fatty acid vinyl ester copolymer 2 to 40% by weight [provided that (A) and
(B) is 100% by weight], and the average particle diameter of the copolymer component (A) dispersed in the acrylic water-based pressure-sensitive adhesive composition. Is 0.3 μm or more, and the average particle diameter of the copolymer component (B) is less than 0.3 μm, and the elongation of a film formed from the water-dispersed acrylic pressure-sensitive adhesive composition. But 1100-1400%
Acrylic pressure-sensitive adhesive composition characterized by the following:

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

(A-1) 40 to 99.8% by weight of an acrylate ester represented by the following general formula (3), wherein the homopolymer has a glass transition point of -20 ° C. or less:

CH ₂ ＣＨCH—COOR ³ (3) wherein R ³ is 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 0-5% by weight of di-carboxylic acid,

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

(A-4) Comonomers other than the monomers (a-1) to (a-3) copolymerizable with the monomers (a-1) to (a-3) 0-60% by weight,

Is an acrylic copolymer obtained by emulsion copolymerization of the acrylic copolymer having a glass transition point of -20.
It is preferably an acrylic copolymer having a temperature of not more than ° C.

The monomer (a-1) has the general formula CH ₂ ＣＨCH—
Is an acrylate ester represented by COOR ³ , wherein R ³ is a linear or branched alkyl group having 2 to 12 carbon atoms, and the glass transition point of the homopolymer is −20 ° C. or lower. .

Examples of such groups R ³ include ethyl, n-propyl, n-butyl, i-butyl, n-hexyl, n-octyl, i-octyl, 2-ethylhexyl Group, n-nonyl group, i-nonyl group, n-decyl group, n-dodecyl group and the like. Among them, n-butyl group, n-hexyl group, n-octyl group, i-octyl group, 2-ethylhexyl group, n-nonyl group, i-nonyl group, n-decyl group, etc. And a straight-chain or branched alkyl group of 6 to 9 carbon atoms such as an n-hexyl group, an n-octyl group, an i-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an i-nonyl group. Chain or branched alkyl groups are particularly preferred.

Specific examples of such acrylates include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, and n-butyl acrylate.
Hexyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate,
Examples thereof include n-nonyl acrylate and i-nonyl acrylate.

The amount of the acrylic acid ester used as the monomer (a-1) is 100% by weight in total of the monomers (a-1) to (a-4).
The content is preferably 40 to 99.8% by weight, preferably 45 to 98% by weight, particularly preferably 50 to 96.5% by weight. Monomer (a-1)
If the amount used is equal to or more than the lower limit amount, the adhesion of the pressure-sensitive adhesive layer to be formed, the balance between tack and cohesive force is excellent, and if it is equal to or less than the upper limit amount, the cohesive force is lower. This is preferable because inconvenience such as shortage does not occur.

The monomer (a-2) is an α, β having 3 to 5 carbon atoms.
-Unsaturated mono- or di-carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid,
Maleic acid, fumaric acid, crotonic acid, citraconic acid and the like can be mentioned. Among these, acrylic acid,
The use of methacrylic acid is more preferred.

The amount of the monomer (a-2) used is
In general, O to 5% by weight, preferably 0.1 to 4% by weight, and particularly preferably 0.3 to 3% by weight in the total of 100% by weight of (a-1) to (a-4).
% By weight. The amount of the monomer (a-2) to be used is preferably not more than the upper limit amount, since inconveniences such as reduction in tackiness and water resistance of the formed pressure-sensitive adhesive layer do not occur. On the other hand, when the used amount is 0.1% by weight or more, the mechanical stability of the obtained pressure-sensitive adhesive aqueous composition and the adhesive force of the obtained pressure-sensitive adhesive layer are moderate and excellent in cohesion. It is preferable to select and use them appropriately in the above-mentioned usage amount range.

The monomer (a-3) is a monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule. It is a monomer other than -2). As such a monomer (a-3), a monomer having a functional group such as 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. And a monomer having two or more radically polymerizable unsaturated groups in the molecule.

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

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, Hydroxyl-containing monomers such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and allyl alcohol; epoxy such as glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, and glycidyl methallyl ether (preferably glycidyl acrylate and glycidyl methacrylate); Group-containing monomers; mercapto group-containing monomers such as allyl mercaptan;

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
Monomers having two or more radically polymerizable unsaturated groups such as (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate;

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. And a group of monomers.

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

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

The comonomer (a-4) includes, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2 -Ethylhexyl methacrylate, i-
Methacrylates 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)
(Preferably vinyl acetate) and other saturated fatty acid vinyl esters; for example, aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene (preferably styrene); and, for example, acrylonitrile, methacrylonitrile and the like (preferably Is a vinyl cyanide monomer of acrylonitrile); 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, Maleic acid or fumarate esters such as n-butyl fumarate, di-2-ethylhexyl fumarate, di-n-octyl fumarate and the like can also be used.

The amount of the comonomer (a-4) used is generally 0 to 50% by weight based on 100% by weight of the total of the monomers (a-1) to (a-4). It is preferably from 0 to 40% by weight, more preferably from 5 to 40% by weight, particularly preferably from 10 to 30% by weight. The amount of the comonomer (a-4) varies depending on the type thereof, and thus cannot be unambiguously determined.However, the balance between adhesion and tack and the balance between these and cohesion may be determined as desired. Since it serves to adjust, the amount can be appropriately selected within the above range so as to meet such purpose. It is preferable that the amount of the comonomer (a-4) used is equal to or less than the upper limit of the above-mentioned range, since inconvenience such as excessively small tack does not occur. Further, by setting the used amount to 5% by weight or more, an improvement in adhesive strength or cohesive strength can be expected.

The acrylic copolymer used in the present invention is preferably obtained by copolymerizing the monomers (a-1) to (a-4), and has a Tg of -40 ° C. or lower. It is necessary to be. When Tg is higher than the above temperature, the tackiness of the obtained pressure-sensitive adhesive layer tends to be insufficient, and adhesion at a low temperature of, for example, 10 ° C. or less, especially for non-polar polymer such as polyethylene film, It is not preferable because the adhesiveness to a film or a molded product may be insufficient.

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

Glass transition point: Approximately 10 mg of a sample of an aqueous dispersion of an acrylic copolymer was weighed into a cylindrical cell made of aluminum foil having a thickness of about 0.05 mm and having 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. SSC-5000 Differential Scanning Calorimeter (Seffe Electronics)
The temperature is measured at a rate of 10 ° C / min from -150 ° C using a tial scanning calorimeter).

The gel content of the acrylic copolymer used in the present invention is preferably at least 40% by weight.
Particularly preferably, the content is 50 to 80% by weight. When the gel content is equal to or more than the lower limit, the cohesive strength and the secondary workability are excellent, which is preferable. Further, when the value is equal to or less than the upper limit, problems such as insufficient adhesive strength and anchoring property of the pressure-sensitive adhesive layer to the support are not caused, and thus it is preferable.

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

Gel content: (a) Preparation of sample film The thickness of the obtained acrylic copolymer sample film was about 10
An aqueous dispersion of an acrylic copolymer was applied on a release material so as to have a thickness of 0 μm, and dried at room temperature for about 1 hour.
Dry at 2 ° C. for 2 minutes to prepare a sample film.

(B) Hot water extraction The sample film of (a) was cut into a size of about 5 cm × about 15 cm, wound uniformly on a glass rod of about 1.5 cmφ measured in advance, and weighed. Obtain the film weight (W ₁ ). The sample film wound around the glass rod was placed in a cylindrical filter paper for Soxhlet extraction, and the sample film was collected using a Soxhlet extractor.
Perform hot water extraction at reflux temperature (about 100 ° C) for hours. The resulting hot water extract is heated to dryness to obtain a hot water extract weight (w ₁ )
Get.

(C) Extraction with ethyl acetate A sample film wound around a glass rod in the same manner as in (b) above
(W ₂ ) is extracted with ethyl acetate at reflux temperature (about 77 ° C.) for 4 hours using a Soxhlet extractor. The obtained ethyl acetate extract is heated to dryness to obtain an ethyl acetate extract weight (w ₂ ).

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

[0050]

(Equation 1)

The acrylic water-based pressure-sensitive adhesive composition contains, as described later, an acrylic copolymer, an α-olefin-saturated fatty acid vinyl ester copolymer, and a surfactant, for example, a pigment, an inorganic filler. When the composition contains an additive such as an agent, for example, the pressure-sensitive adhesive composition is appropriately diluted with ion-exchanged water or the like to reduce the viscosity (for example, about 50 cps or less), and then the number of rotations and the rotation time are reduced. By adjusting and centrifuging to separate these additives, an aqueous dispersion of an acrylic copolymer and an α-olefin-saturated fatty acid vinyl ester copolymer used for the measurement of the glass transition point and the gel content is obtained. It is possible to separate and collect. The reason why such separation is possible is that the specific gravity of the acrylic copolymer used in the present invention is very close to 1, and other copolymers usually used in α-olefin-saturated fatty acid vinyl ester copolymers and pressure-sensitive adhesive compositions. This is because it is considerably lighter than the additive.

Suitable methods for producing the acrylic copolymer used in the present invention include, for example, the methods (a-1) to (a-
The monomer of 4), if necessary, in the presence of a water-soluble protective colloid,
An embodiment in which an appropriate surfactant is used as an emulsifier for polymerization and emulsion copolymerization is carried out in an aqueous medium.

The above-mentioned surfactant which can be used in the present invention is not particularly limited, and various ordinary surfactants used for emulsion polymerization can be used. From the viewpoint of good water resistance of the layer, having a radical polymerizable unsaturated group in the molecule,
The use of so-called "reactive emulsifiers" is preferred.

Examples of such a reactive emulsifier include “Eleminol JS-2” and “Eleminol RS-30”.
[The above are manufactured by Sanyo Chemical Industry Co., Ltd.], "Aquaron HS-10
N '', `` AQUARON HS-20N '' (Daiichi Kogyo Seiyaku Co., Ltd.
Adecaria Soap SE-10N) (Asahi Denka Kogyo Co., Ltd.)
Made), `` Latemul S-120 '', `` Latemul S-120A '',
Anionic reactive emulsifiers such as "Latemul S-180" and "Latemul S-180A" (all manufactured by Kao Corporation); for example, "Aqualon RN-20", "Aqualon RN-30", "Aqualon RN- 50 "(manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)," Adecaria Soap NE-10 "," Adecaria Soap NE-20 "," Adecaria Soap NE-30 "(manufactured by Asahi Denka Kogyo Co., Ltd.) , "RMA-
564 '', `` RMA-568 '', `` RMA-1114 '' (Nippon emulsifier
Nonionic emulsifiers, etc .;

The amount of the reactive emulsifier used is determined by the amount of the monomer
(a-1) to (a-4) 100 parts by weight in total, for example, 0.05
An amount of about 10 to 10 parts by weight, preferably about 0.1 to 5 parts by weight can be exemplified. If the amount used is greater than or equal to the lower limit,
The obtained acrylic water-based pressure-sensitive adhesive composition is preferable because the mechanical stability is good. On the other hand, if it is equal to or less than the upper limit, the formed pressure-sensitive adhesive layer has excellent cohesive strength and water resistance. Is preferred.

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

Examples of the nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; and polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether. Oxyethylene alkylphenol ethers; for example, sorbitan monolaurate;
Sorbitan higher fatty acid esters such as sorbitan monostearate and sorbitan trioleate;

For example, higher fatty acid esters of polyoxyethylene sorbitan such as polyoxyethylene sorbitan monolaurate; higher fatty acid esters of polyoxyethylene such as polyoxyethylene monolaurate and polyoxyethylene monostearate; Glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride; for example, polyoxyethylene / polyoxypropylene / block copolymer;

Examples of the anionic surfactants include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzenesulfonate; alkyl sulfates such as sodium lauryl sulfate Salts; for example, polyoxyethylene alkyl ether sulfate salts such as sodium polyethoxyethylene lauryl ether sulfate;

For example, polyoxyethylene alkyl aryl ether sulfates such as sodium polyoxyethylene nonylphenol ether sulfate; alkyl sulfosuccinates such as sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate and sodium polyoxyethylene lauryl sulfosuccinate; Derivatives thereof; and the like.

When these surfactants are used as an emulsifier for polymerization, they are preferably used in combination as appropriate, and the amount of the surfactant used is generally the above-mentioned monomers (a-1) to (a-
An amount of about 0 to 10 parts by weight can be exemplified with respect to the total 100 parts by weight of 4).

These surfactants are used not only as emulsifiers for polymerization, but also to improve the mechanical stability of the resulting pressure-sensitive adhesive aqueous composition and to release the material (paper or plastic film subjected to release treatment with a silicone resin or the like). It is often added after the above-mentioned aqueous emulsion copolymerization for the purpose of improving the coatability of the emulsion. For example, a transfer method (after applying the pressure-sensitive adhesive composition on a release material and drying to form a pressure-sensitive adhesive layer,
A method in which the substrate is overlaid on the pressure-sensitive adhesive layer and pressurized, and the pressure-sensitive adhesive layer is transferred onto the substrate).
The sulfosuccinate ester-based anionic surfactants exemplified in the above-mentioned anionic surfactants are often used.

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

As the water-soluble protective colloid, for example, polyvinyl alcohol such as partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, and modified polyvinyl alcohol (hereinafter sometimes abbreviated as PVA)
And cellulose derivatives such as hydroxyethylcellulose, hydroxypropylcellulose and carboxymethylcellulose salts; and natural polysaccharides such as guar gum;
And the like, and these can be used alone or in combination of two or more.

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

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

Further, in the aqueous emulsion copolymerization, it is preferable to use a chain transfer agent in order to obtain a copolymer having the above-mentioned weight average molecular weight. As such a chain transfer agent, for example, n-dodecyl Mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, 2-ethylhexyl thioglycolate, 2-mercaptoethanol, trichlorobromomethane and the like can be mentioned. These chain transfer agents are preferably used in an amount of about 0 to 1 part by weight based on a total of 100 parts by weight of the monomers (a-1) to (a-4).

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

The average particle size of the copolymer particles in the aqueous dispersion of the acrylic copolymer thus obtained needs to be 0.3 μm or more, preferably 0.5 to 2 μm, particularly preferably 0.6 to 2 μm. 1 μm. When the average particle size is too small, being less than the lower limit, the cohesive force of the obtained pressure-sensitive adhesive layer is insufficient, or the temporal stability and the secondary workability of the obtained pressure-sensitive adhesive sheet are preferably reduced. Absent. On the other hand, when the content is equal to or less than the upper limit, the film formability at the time of forming the pressure-sensitive adhesive layer is excellent, and there is almost no generation of undesired aggregates in the production of the aqueous dispersion.

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

Average particle diameter: The copolymer emulsion was diluted 50,000 to 150,000 times with distilled water, and thoroughly stirred and mixed.
About 10 ml using a Pasteur pipette in a mmφ glass cell
The sample was collected, set at a predetermined position on a dynamic light scattering photometer "DLS-700" (manufactured by Otsuka Electronics Co., Ltd.), and measured under the following measurement conditions. Find the particle size.

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

The pH of the aqueous dispersion of the acrylic copolymer obtained as described above can be adjusted with ammonia water or the like, if necessary. Such dispersions have a solids concentration of 30-70% by weight, preferably 45-65% by weight,
30003000 cps (BH-type rotational viscometer, 25 ° C., 20 rpm; viscosity measurement conditions are the same as described below), and pH is preferably about 2 to 8.

The acrylic water-based pressure-sensitive adhesive composition of the present invention comprises an α-olefin-saturated fatty acid vinyl ester-based copolymer (B) together with the above-mentioned acrylic copolymer (A) as a copolymer component. It comprises.

The above α-olefin-saturated fatty acid vinyl ester copolymer (B) includes the following monomers (b-1) to (b-5) (provided that (b-1) to (b-5) The total is 100% by weight],

(B-1) 5 to 40% by weight of an α-olefin represented by the following general formula (1): CH ₂ ＣＨCH—R ¹ ‥‥‥ (1) wherein R ¹ is hydrogen or carbon number Shows a linear or branched alkyl group of 12 or less]

(B-2) 62 to 90% of a saturated fatty acid vinyl ester represented by the following general formula (2): CH ₂ ＣＨCH—OCOR ² (2) wherein R ² is hydrogen Or a linear or branched alkyl group having 1 to 18 carbon atoms)

(B-3) 0 to 5% by weight of an α, β-unsaturated mono- or dicarboxylic acid having 3 to 5 carbon atoms,

(B-4) A monomer having at least one functional group in addition to one radically polymerizable unsaturated group in the molecule, and a monomer other than the above (b-3) ~ 5% by weight, and

(B-5) Comonomers copolymerizable with the monomers (b-1) to (b-4) and other than the monomers (b-1) to (b-4) 0-10
weight%,

The glass transition point of the copolymer must be -10 ° C to -30 ° C, preferably -15 to -28 ° C.

The monomer (b-1) is an α-olefin represented by the following general formula (1). CH ₂ ＣＨCH-R ¹ ‥‥‥ (1)

In the above formula, R ¹ represents hydrogen or a linear or branched alkyl group having 12 or less carbon atoms, such as hydrogen, methyl, ethyl, n-propyl, Examples thereof include an n-butyl group and an n-decyl group. Specific examples of such α-olefins include:
For example, ethylene, n-propylene, 1-butene, n-hexene, n-dodecene and the like can be mentioned, and the use of ethylene is particularly preferred.

The copolymerization amount of the α-olefin which is the monomer (b-1) is 5 to 40 in the total of 100% by weight of the monomers (b-1) to (b-5).
%, Preferably 10-38% by weight, more preferably 20-36% by weight, particularly preferably 25% by weight.
~ 35% by weight. If the copolymerization amount of the α-olefin is less than the lower limit and is too small, the adhesive force to the non-polar polymer of the pressure-sensitive adhesive layer formed by the obtained pressure-sensitive adhesive composition, the low-temperature adhesiveness and the curved surface adhesiveness are reduced. On the other hand, if it exceeds the upper limit, it is not preferable because the tackiness of the pressure-sensitive adhesive layer decreases.

The monomer (b-2) is a saturated fatty acid vinyl ester represented by the following general formula (2). CH ₂ = CH-OCOR ² ‥‥‥ (2)

In the above formula, R ² is hydrogen or a group having 1 to 1 carbon atoms.
8 represents a linear or branched alkyl group, specific examples of such a saturated fatty acid vinyl ester,
For example, vinyl formate, vinyl acetate, vinyl propionate, "vinyl versatate" (trade name) and the like can be mentioned, and the use of vinyl acetate is preferable.

The copolymerization amount of the saturated fatty acid vinyl ester as the monomer (b-2) is 100% by weight in total of the monomers (b-1) to (b-5).
Medium, preferably 62 to 90% by weight, more preferably 64 to 80% by weight.
%, Particularly preferably 65 to 75% by weight. When the amount of the saturated fatty acid ester copolymerized is too small below the lower limit, the resulting pressure-sensitive adhesive layer is insufficient in cohesive strength, and is not preferred. It is not preferable because the low-temperature adhesion, the curved surface adhesion and the water resistance of the agent layer are insufficient.

The monomer (b-3) has the same carbon number of 3 to 3 as the monomer (a-2) exemplified in the acrylic copolymer.
5, an α, β-unsaturated mono- or di-carboxylic acid,
Specific examples thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid. Among these, acrylic acid and methacrylic acid are more preferably used.

The amount of the monomer (b-3) used is the same as that of the monomer (b-1)
In the total of 100% by weight of (b-5), it is generally O to 5% by weight, preferably 0.1 to 4% by weight, particularly preferably 0.3 to 3% by weight. If the amount of the monomer (b-3) is too large, exceeding the upper limit, the tackiness and water resistance of the formed pressure-sensitive adhesive layer may be undesirably reduced. On the other hand, the amount used is 0.
When the content is 1% by weight or more, the mechanical stability of the obtained aqueous composition of the pressure-sensitive adhesive and the adhesive force of the obtained pressure-sensitive adhesive layer are moderate and excellent in cohesion. It is better to select and use it appropriately.

The monomer (b-4) has at least one radically polymerizable unsaturated group in the molecule, similarly to the monomer (a-3) in the acrylic copolymer. And a monomer other than the monomer (b-3). As such a monomer (b-4), as a functional group as described above, 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. And a monomer having two or more radically polymerizable unsaturated groups in the molecule. Examples of such a monomer include the same ones as exemplified in the acrylic copolymer.

The above-mentioned monomer (b-5) includes monomers (b-1) to (b-4)
And the monomers (b-1) to (b-4) are copolymerizable monomers other than the monomers, and as such a monomer (b-5), the acrylic copolymer The monomers (a-1) and (a-
4), that is, acrylic acid ester, methacrylic acid ester, aromatic vinyl monomer, vinyl cyanide monomer, maleic acid or fumaric acid ester mentioned in the monomers (a-1) and (a-4) Etc. can be used.

The amount of the comonomer (b-5) used is generally 0 to 10% by weight based on 100% by weight of the total of the monomers (b-1) to (b-5). , Preferably 0 to 8% by weight, particularly preferably 0 to 5% by weight. The amount of the comonomer (b-5) varies depending on the type thereof, and thus cannot be unambiguously determined.However, the balance between adhesion and tack and the balance between these and cohesion can be determined as desired. Since it serves to adjust, the amount can be appropriately selected within the above range so as to meet such purpose. If the use amount of the comonomer (b-5) exceeds the upper limit of the above range and is too large, the secondary workability may deteriorate, which is not preferable.

The α-olefin-saturated fatty acid vinyl ester copolymer (B) used in the present invention comprises the monomer (b-1)
~ (B-5) is copolymerized, and its Tg is -10 ~
It needs to be -30 ° C. If the Tg is higher than the upper limit temperature, the obtained pressure-sensitive adhesive layer tends to be insufficient in tack, low-temperature adhesiveness and curved surface adhesiveness. It is not preferable because the secondary workability of a sheet or the like deteriorates.

The gel content of the α-olefin-saturated fatty acid vinyl ester copolymer used in the present invention is preferably 10% by weight or more, and 15 to 80% by weight.
Is particularly preferred. When the gel content is equal to or more than the lower limit, the cohesive strength is not insufficient, which is preferable. Further, when the value is equal to or less than the upper limit, problems such as insufficient adhesive strength and anchoring property of the pressure-sensitive adhesive layer to the support are not caused, and thus it is preferable.

The preferred method for producing the α-olefin-saturated fatty acid vinyl ester copolymer as the copolymer component (B) in the present invention includes the monomers (b-1) and (b-
2), and, if necessary, a monomer comprising the monomers (b-3) to (b-5), and the acrylic copolymer under pressure as appropriate.
It can be obtained by emulsion copolymerization in the presence of the same emulsifier, protective colloid and the like as used in the production of (A), and in the presence of a radical polymerization initiator, a pH regulator and a polymerization degree regulator.

The average particle size of the copolymer particles in the aqueous dispersion of the α-olefin-saturated fatty acid vinyl ester copolymer used in the present invention must be less than 0.3 μm, preferably 0.25 μm or less. Particularly preferably 0.05 to 0.2
3 μm. If the average particle size is too large exceeding the upper limit, the compatibility with the acrylic copolymer becomes poor,
It is not preferable because the resulting pressure-sensitive adhesive layer has insufficient adhesive strength and the obtained pressure-sensitive adhesive sheet has poor temporal stability and secondary workability. On the other hand, if not less than the lower limit,
In the production of the aqueous dispersion, it is preferable because there is almost no generation of undesirable aggregates.

In the present invention, the glass transition point, the gel content, and the average particle size of the α-olefin-saturated fatty acid vinyl ester copolymer are values measured and determined in the same manner as in the acrylic copolymer.

The aqueous dispersion of the α-olefin-saturated fatty acid vinyl ester copolymer has a solid content of 30 to 70% by weight, preferably 45 to 65% by weight, and a viscosity of 50 to 3000 cp.
s, pH 2-8 is good.

The acrylic water-based pressure-sensitive adhesive composition of the present invention comprises the above-mentioned acrylic copolymer (A) 6 as a copolymer component.
0 to 98% by weight, preferably 65 to 96% by weight, particularly preferably 70 to 95% by weight, and 2 to 40% by weight, preferably 4 to 35% by weight of the α-olefin-saturated fatty acid vinyl ester copolymer (B). % By weight, particularly preferably 5 to 30% by weight, provided that the sum of (A) and (B) is 100% by weight.

If the blending amount of the copolymer component (B) exceeds the above upper limit and is too large, the tackiness of the resulting pressure-sensitive adhesive layer tends to be insufficient, and the cohesive strength and water resistance are also reduced. It is not preferable because there are many. On the other hand, the copolymer component (B)
Is too small, less than the above lower limit, the resulting pressure-sensitive adhesive layer tends to have insufficient adhesion to the non-polar polymer and tends to have poor secondary workability, which is not preferred.

The acrylic water-based pressure-sensitive adhesive composition of the present invention comprises the acrylic copolymer (A) and the α-olefin-saturated fatty acid vinyl ester copolymer (B) from the viewpoint of easy production. ) Can be prepared by mixing each of them in the form of an aqueous dispersion, and adding and blending an appropriate compound to this as needed.

A method for forming a pressure-sensitive adhesive layer using the acrylic water-based pressure-sensitive adhesive composition of the present invention includes directly applying the pressure-sensitive adhesive composition on a substrate such as paper or plastic film. A direct method of coating and drying can be employed.
Further, the pressure-sensitive adhesive composition is applied onto a release material such as paper or a plastic film that has been release-treated with silicone or the like, and dried to form a pressure-sensitive adhesive layer. A method in which the substrate is overlaid on the pressure-sensitive adhesive layer and pressed to transfer the pressure-sensitive adhesive layer onto the substrate can also be used.

In the above transfer method, the composition of the present invention is usually thickened using various thickeners. Examples of such thickeners include sodium polyacrylate, the PVAs,
Examples of the cellulose derivative, an aqueous dispersion-type poly (meth) acrylic acid-based copolymer thickener that is thickened by alkali, and the like can be given. The amount of these thickeners can be appropriately determined depending on the desired viscosity, and is 0 to 10 parts by weight, preferably 0 to 5 parts by weight as a solid content relative to 100 parts by weight of the acrylic copolymer. Range.

Further, the pressure-sensitive adhesive composition of the present invention may be used as long as the desired performance is not impaired, for example, coumarone-indene resin, terpene resin, terpene-phenol resin, rosin resin, pt-butylphenol-acetylene resin, phenol・ A tackifier such as formaldehyde resin, xylene / formaldehyde resin, petroleum hydrocarbon resin, hydrogenated hydrocarbon resin, turpentine resin, etc .; for example, various modifying resins such as synthetic rubber and natural rubber are used. be able to.

The addition amount of these tackifiers and / or various modifying resins can be appropriately selected from the viewpoint of the balance between the adhesive force to the non-polar polymer and the cohesive force.
For example, 0 to 60 parts by weight, preferably 0 to 30 parts by weight, based on 100 parts by weight of the total of (B) and (B), can be exemplified.

Further, the pressure-sensitive adhesive composition of the present invention may contain a plasticizer, a wetting agent, a coloring agent, an inorganic filler, a stabilizer, an antifoaming agent, a preservative, an antifungal agent and the like, if necessary. Can be used.

The acrylic water-based pressure-sensitive adhesive composition of the present invention thus obtained generally has a solid concentration of 30 to 70% by weight, a viscosity of 100 to 15000 cps, and a pH of about 3 to 8;
When used for the transfer method, a solid content concentration of 30 to 70% by weight, a viscosity of 3000 to 15000 cps, and a pH of 4 to 8.5 are preferred.

The elongation of the film formed from the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention is 1100 to 1400.
% Is particularly preferred. When the film elongation is not more than the upper limit, the secondary workability of the obtained pressure-sensitive adhesive sheet is excellent, and therefore, when the film elongation is not less than the lower limit, the adhesive strength and the low temperature of the obtained pressure-sensitive adhesive sheet are low. It is preferable because of excellent adhesiveness.

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

Film elongation: A sample of the pressure-sensitive adhesive composition was placed on a release material, and the dried pressure-sensitive adhesive layer was 100 ± 10 μm.
It is applied using a doctor blade so as to obtain a solution, left at 25 ° C. for about 30 minutes to be semi-dried, and then dried at 100 ° C. for 10 minutes using a hot-air circulation dryer. On the surface of the created film
A cellophane tape is adhered in two rows in parallel at 10 mm intervals to reinforce the film, and cut at 10 mm intervals in a direction perpendicular to the longitudinal direction of the cellophane tape to obtain test pieces. The tensile test is performed using a self-recording tensile tester in a constant temperature and humidity room at 23 ° C. and 65% RH.

The test piece is fixed with the cellophane tape knob jig, is attached in a vertically stress-free state with a space of 10 mm between the film portions to be subjected to a tensile test, and is pulled at a tensile 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 determined according to the following equation. The numerical value is the average value of the results of five test pieces.

Film elongation = {length at break (cm) −1} × 100 (%)

[0114]

EXAMPLES The present invention will be described in more detail with reference to Examples along with Comparative Examples and Reference Examples. The preparation of the test pressure-sensitive adhesive sheet and the measurement of various physical properties such as normal state adhesive strength, tack, cohesive strength, low-temperature adhesiveness, curved surface adhesiveness, and pressure-sensitive adhesive sheet cutability are as follows.

(1) Preparation of Test Pressure-Sensitive Adhesive Sheet A sample of the pressure-sensitive adhesive composition was applied on a release material such that the dried pressure-sensitive adhesive layer was 20 ± 3 g / m ^2. , 100 ℃
For 90 seconds in a hot air circulating dryer, and then fine wood <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), a test piece cut out from the test pressure-sensitive adhesive sheet prepared in the previous section (1) was crimped according to the method of JIS Z-0237, and after 24 hours, 23 ° C, 65% RH, peeling rate The peel strength (g / 25 mm) is measured under the condition of 300 mm / min.

(3) Measurement of tack According to the J. Dow method, a test piece (length: 100 mm) cut out from the test pressure-sensitive adhesive sheet prepared in (1) above on a slope having a tilt angle of 30 °
Is attached, and a steel ball having a value diameter of x / 32 inches is rolled from a position 100 mm above the slope of the test piece, and is indicated by the size x of the largest diameter ball stopped on the sample.

(4) Measurement of cohesive force A test piece cut out from the test pressure-sensitive adhesive sheet prepared in the preceding section (1) was applied to a SUS plate treated in the same manner as in the preceding section (2), and the adhesion area was 25%. × 25 mm ² , and pressed back and forth with a 2 kg roller once. A 1 kg static load is applied to the sample in an atmosphere of 40 ° C. × 30% RH, and the time until the load drops is measured.

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

(6) Curved Surface Adhesion A test piece of 10 × 20 mm ² was cut out from the pressure-sensitive adhesive sheet prepared in the above item (1), and a polyethylene rod of φ = 10 mm [PE plate used in the item (2) above] Material of the same type as above), 23 ℃, 65
After standing for 24 hours under the condition of% RH, the state of floating of the test piece from the rod is observed.

；: No lifting Δ: slightly floating ×: completely floating

(7) Cutability The test piece 1 having a width of 5 cm was obtained from the pressure-sensitive adhesive sheet prepared in the above (1).
00 sheets are cut out, and the state of blade contamination when these are cut ten times by a cutting machine is observed.

；: No stain Δ: Slight stain ×: Stain is large

(8) Stability test of adhesive force over time After the pressure-sensitive adhesive sheet prepared in the previous section (1) was allowed to stand at 50 ° C. and 95% RH for 5 days, it was applied to a PE plate according to the method in the previous section (2). The adhesive strength is measured, and the rate of change in the adhesive strength is measured with the adhesive strength before standing as 100%.

Reference Example 1 70 parts by weight of ion-exchanged water, 0.04 part 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 inlet tube and a reflux condenser. 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
-[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 a polyoxyethylene alkylphenol ether type nonionic surfactant (HLB = about 9) and 0.2 parts by weight of partially saponified PVA (degree of polymerization: 300) are stirred and dissolved. Ethylhexyl acrylate (EHA) 84 parts by weight, methyl methacrylate (MMA) 15
A monomer mixture composed of parts by weight 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 stream of nitrogen, and while maintaining the temperature of the contents at 80 ° C., the above monomer premix was added successively to a 4% by weight aqueous solution of APS to initiate polymerization. The polymerization reaction was performed for an hour. After the completion of the polymerization reaction, stirring was continued for about 1 hour at the same temperature, followed by cooling, 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 the 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, instead of using 15 parts by weight of MMA, 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 3 In Reference Example 1, 84 parts by weight of EHA, 15 parts by weight of MMA, and AA
Instead of using 1 part by weight, use 70 parts by weight of EHA, 10 parts by weight of butyl acrylate (BA), 1 part by weight of methacrylic acid (MAA), 0.5 part by weight of acrylamide (AMD), 10 parts by weight of MMA and 8.5 parts by weight of VAc. 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 4 The procedure of Reference Example 1 was repeated, except that instead of using 84 parts by weight of EHA and 15 parts by weight of MMA, 59 parts by weight of EHA and 40 parts by weight of MMA were 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 5 In Reference Example 1, no partially saponified PVA was used, and
"AQUALON HS-10" as an emulsifier initially added in the reactor
An aqueous dispersion of an acrylic copolymer was obtained in the same manner as in Reference Example 1 except that an aqueous dispersion of an acrylic copolymer was prepared by adding 0.2 parts by weight. Table 1 shows the monomer composition and characteristic values of the acrylic copolymer, and the characteristics of the aqueous dispersion thereof.

[0133]

[Table 1]

Reference Example A In a pressure-resistant autoclave equipped with a stirrer, 73 parts by weight of ion-exchanged water at room temperature, 2.0 parts by weight of sodium lauryl sulfate as an anionic surfactant, and polyoxyethylene nonylphenol ether as a nonionic surfactant were used. 5.0
Parts by weight, an aqueous solution consisting of 1.0 parts by weight of partially saponified PVA, 0.06 parts by weight of acetic acid, 0.3 parts by weight of sodium acetate and 0.6 parts by weight of formaldehyde sulfoxylate sodium salt as protective colloids, and nitrogen and ethylene substitution were carried out with stirring. Was.

Next, the temperature in the system was heated to 50 ° C., and 70 parts by weight of VAc and 32 parts by weight of a 5% by weight aqueous solution of APS were simultaneously dropped uniformly over 6 hours. During this time, the reaction temperature was adjusted to 50 ° C., and the ethylene (Et) pressure was constantly adjusted to 60 kg / cm ² during the polymerization. Thereafter, the mixture was further aged at 50 ° C. for 2 hours to obtain an aqueous dispersion of an α-olefin-saturated fatty acid vinyl ester-based copolymer.

The characteristics of this dispersion are as follows: solid content: 50.1% by weight;
pH 5.8, viscosity 400 cps, average particle diameter 0.19 μm. The monomer composition of the α-olefin-saturated fatty acid vinyl ester-based copolymer is 30% by weight of Et and 70% by weight of VAc, and the copolymer has a glass transition point of −53 ° C. and a gel content of 30% by weight. %Met.

Reference Example B and Reference Example a The same procedure as in Reference Example A was carried out except that the amount of VAc was changed and the Et pressure was changed. A dispersion was obtained. α-
Table 2 shows the monomer composition and characteristic values of the olefin-saturated fatty acid vinyl ester copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example C In Reference Example A, instead of using 70 parts by weight of VAc,
An aqueous dispersion of an α-olefin-saturated fatty acid vinyl ester copolymer was obtained in the same manner as in Reference Example A except that a monomer mixture consisting of 69 parts by weight and 1 part by weight of AA was used. α-
Table 2 shows the monomer composition and characteristic values of the olefin-saturated fatty acid vinyl ester copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example D In Reference Example A, VAc 70 was used instead of using 70 parts by weight of VAc.
Using a monomer mixture consisting of 5 parts by weight of EHA and 5 parts by weight of EHA,
An aqueous dispersion of an α-olefin-saturated fatty acid vinyl ester copolymer was obtained in the same manner as in Reference Example A except that the Et pressure was changed. Table 2 shows the monomer composition and characteristic values of the α-olefin-saturated fatty acid vinyl ester copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example b In Reference Example A, instead of using 70 parts by weight of VAc, VAc 65 was used.
Using a monomer mixture consisting of 15 parts by weight of EHA and 15 parts by weight of EHA,
An aqueous dispersion of an α-olefin-saturated fatty acid vinyl ester copolymer was obtained in the same manner as in Reference Example A except that the Et pressure was changed. Table 2 shows the monomer composition and characteristic values of the α-olefin-saturated fatty acid vinyl ester copolymer, and the characteristics of the aqueous dispersion thereof.

Reference Example c In the same manner as in Reference Example A except that sodium lauryl sulfate and partially saponified PVA were not used and 1.0 part by weight of hydroxyethyl cellulose was used, the copolymer of α-olefin-saturated fatty acid vinyl ester was used. A combined aqueous dispersion was obtained. Table 2 shows the monomer composition and characteristic values of the α-olefin-saturated fatty acid vinyl ester copolymer, and the characteristics of the aqueous dispersion thereof.

[0142]

[Table 2]

Example 1 159 parts by weight of the dispersion of Reference Example 1 (about 80 acrylic copolymers)
Parts by weight), 40 parts by weight of the dispersion of Reference Example A (about 20 parts by weight of an α-olefin-saturated fatty acid vinyl ester copolymer),
A sodium dioctyl sulfosuccinate type anionic surfactant having a solid concentration of 40% by weight was added in an amount of 0.5 part by weight, and then an alkali thickener and aqueous ammonia were added thereto to adjust the pH to 7.
A water-based pressure-sensitive adhesive composition having a pressure of about 10,000 cps was obtained.

Using this composition, a pressure-sensitive adhesive sheet for a test was prepared in accordance with the method (1), and various physical properties were measured.
Physical properties of the pressure-sensitive adhesive sheet were measured according to (2) to (8).
Table 3 shows the composition and characteristic values of the pressure-sensitive adhesive composition, and Table 4 shows various physical properties of the pressure-sensitive adhesive sheet.

Examples 2 to 4 and Comparative Examples 1 to 2 In Example 1, the proportions of the dispersion of Reference Example 1 and the dispersion of Reference Example A were changed, or only the dispersion of Reference Example 1 was used. Example 1 except that the dispersion of Reference Example A was not used
An aqueous pressure-sensitive adhesive composition was obtained in the same manner as described above, and a pressure-sensitive adhesive sheet was prepared in the same manner as described above, and the physical properties of the pressure-sensitive adhesive sheet were measured. Table 3 shows the composition and characteristics of the pressure-sensitive adhesive and the characteristics of the aqueous dispersion, and Table 4 shows the properties of the pressure-sensitive adhesive sheet.
Shown in

Examples 5 to 6 and Comparative Examples 3 and 4 The procedure of Example 1 was repeated, except that 159 parts by weight of the dispersions of Reference Examples 1 to 5 were used instead of 159 parts by weight of the dispersion of Reference Example 1. A water-dispersible pressure-sensitive adhesive composition was obtained in the same manner as in Example 1. Thereafter, a pressure-sensitive adhesive sheet was prepared in the same manner, and the physical properties of the pressure-sensitive adhesive sheet were measured. Table 3 shows the composition and characteristics of the pressure-sensitive adhesive, and the characteristics of the aqueous dispersion, and Table 4 shows the physical properties of the pressure-sensitive adhesive sheet.

Examples 7 to 9 and Comparative Examples 5 to 7 In Example 1, instead of using 40 parts by weight of the dispersion of Reference Example A, the dispersions of Reference Examples B to D and Reference Examples a to c were used. Example 1 except that each was used in an amount of 40 parts by weight
A water-dispersible pressure-sensitive adhesive composition was obtained in the same manner as described above, and a pressure-sensitive adhesive sheet was prepared in the same manner as described above, and the physical properties of the pressure-sensitive adhesive sheet were measured. Table 3 shows the composition and characteristics of the pressure-sensitive adhesive, and the characteristics of the aqueous dispersion, and Table 4 shows the physical properties of the pressure-sensitive adhesive sheet.

[0148]

[Table 3]

[0149]

[Table 4]

[0150]

The acrylic water-based pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer having a specific glass transition point, and an α-olefin-saturated fatty acid vinyl having a specific composition and a specific glass transition point. An ester copolymer is blended in a specific amount, and the average particle diameter of the acrylic copolymer and the α-olefin-saturated fatty acid vinyl ester copolymer dispersed in the composition is respectively Acrylic aqueous pressure-sensitive adhesive composition within a specific range.

The composition 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. Excellent adhesion to non-polar polymer films or molded products such as polyolefins, especially excellent curved surface adhesion and low temperature adhesion, as well as excellent secondary workability such as slitting, cutting and punching It is a thing.

If the average particle size of the acrylic copolymer dispersed in the composition of the present invention is too small, or if the average particle size of the α-olefin-saturated fatty acid vinyl ester copolymer is too large, the cohesive force and the ionic copolymer will be reduced. Subsequent workability is reduced, and the stability over time of the adhesive force is deteriorated. If the glass transition point of the acrylic copolymer is too high, the tack becomes small,
Low temperature adhesiveness decreases.

Further, the mixing ratio of the acrylic copolymer and the α-olefin-saturated fatty acid vinyl ester copolymer deviates from the scope of the present invention, and the amount of the α-olefin-saturated fatty acid vinyl ester copolymer is too small even if it is too large. Even after
Low temperature adhesion and secondary workability are reduced.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tetsuo Osaw 53 Yoneyama Minamicho, Sano-shi, Tochigi Japan Carbide Industries Co., Ltd. 3-102 Examiner Kenji Hara (56) References JP-A-3-162473 (JP, A JP-A-2-212573 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 133/08 C09J 131/04

Claims (1)

(57) [Claims] 1. An acrylic copolymer having a glass transition point of -40 ° C. or lower, comprising:
60 to 98% by weight, and the following monomers (b-1) to (b-5)
And the total of (b-1) to (b-5) is 100% by weight], and (b-1)
Α-olefin represented by the general formula (1): 5 to 40% by weight, CH₂= CH-R¹・ ・ ・ ・ ・ (1) [wherein, R¹Is hydrogen or a straight chain having 12 or less carbon atoms or
(Shows a branched alkyl group) (b-2) represented by the following general formula (2)
Saturated fatty acid vinyl ester62-90%,  CH₂= CH-OCOR²・ ・ ・ ・ ・ (2) [wherein, R²Is hydrogen or a straight chain having 1 to 18 carbon atoms or
(B-3) α, β- having 3 to 5 carbon atoms
0 to 5% by weight of unsaturated mono- or di-carboxylic acid, (b-4) in addition to one radically polymerizable unsaturated group in the molecule
A monomer having at least one functional group,
0-5% by weight of a monomer other than (b-3), and (b-5) a copolymerizable with the monomers (b-1) to (b-4)
0 to 10% by weight of a comonomer other than monomers (b-1) to (b-4)
Polymerized α-olefin saturated fatty acid vinyl ester
The α-olefin saturated fatty acid vinyl
The glass transition point of the ester copolymer is -10 ° C to -30 ° C
Α-olefin saturated fatty acid vinyl ester copolymer
2 to 40% by weight, provided that the total of (A) and (B) is 100
Aqueous pressure-sensitive adhesive set comprising
A copolymer, wherein the copolymer is dispersed in the composition
The average particle diameter of the component (A) is 0.3 μm or more, and
The average particle diameter of the copolymer component (B) is less than 0.3 μm
Yes,Formed from the water-dispersed acrylic pressure-sensitive adhesive composition
The elongation of the film to be used is 1100-1400%Features
Pressure-sensitive adhesive composition.