JP2000192006A - Emulsion-type pressure-sensitive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive sheet, etc., excellent in releasability even in a severe environment of high temperature, high humidity, etc., by using a copolymer emulsion prepared from a monomer mixture containing an alkyl (meth)acrylate and a monomer having an N-hydroxyalkyl or N-alkoxyalkyl group. SOLUTION: The copolymer emulsion, used as an emulsion-type pressuresensitive adhesive, is prepared by emulsifying a monomer mixture containing 10-99.9 wt.% alkyl (meth)acrylate represented by the formula: CH2=C (R1)COOR2 (wherein R1 is H or methyl; and R2 is a 4-16C alkyl) and 0.1-10 wt.% monomer having an N-hydroxyalkyl or N-alkoxyalkyl group in water in the presence of an emulsifier to a vol. average particle size of 0.1-5 μm and subjecting the resultant emulsion to polymerization in the presence of a polymerization initiator. The monomer mixture may further contain 0.2-5 wt.% α,β-unsaturated carboxylic acid, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an emulsion type pressure-sensitive adhesive.

[0002]

2. Description of the Related Art From the viewpoint of improving the global environment, working environment, and effective use of resources, there is a demand for conversion to emulsion type adhesives. Adhesive sheets such as surface protection films and adhesive tapes have an adhesive strength suitable for the application, and the adhesive strength does not change over time even when stored under high humidity or high temperature, and when peeling Performances such as easy peeling and no residue or contamination of the adhesive on the adherend after peeling are required. However, conventional emulsion type adhesives are inferior to solvent type in terms of environmental resistance such as moisture resistance, water resistance and heat resistance, so solvent type is often used in applications such as surface protection film and adhesive tape, Conversion to an aqueous emulsion-type pressure-sensitive adhesive has not progressed sufficiently. The adhesive strength of the pressure-sensitive adhesive sheets increases due to changes with time after attachment and environmental changes such as temperature and humidity. As a result, when peeling the pressure-sensitive adhesive sheets from the adherend, the peeling work takes time,
This causes inconvenience such as leaving an adhesive residue on the adherend.

As a method for improving the releasability of an emulsion type pressure-sensitive adhesive, a method of copolymerizing a monomer having an allyl group (for example, JP-A-3-21685) and a method of blending an epoxy compound (for example, a special method) Kaihei 7-157741
No.), a method of blending an oxazoline compound (for example, JP-A No. 10-114887), etc., but the above-mentioned required performance has not been sufficiently satisfied.

[0004]

The present invention provides a water-based emulsion-type pressure-sensitive adhesive that can solve the above problems, and exhibits good peelability even when placed in a harsh environment such as high temperature and high humidity. The purpose is to provide pressure sensitive adhesive sheets.

[0005]

[In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 4 to 16 carbon atoms. ]

The present invention also provides a monomer mixture containing 10 to 99.9% by weight of the monomer (a) and 0.1 to 10% by weight of the monomer (b) in a machine in the presence of an emulsifier. After emulsifying and dispersing in water with force to make the volume average particle diameter 0.1 to 5 μm,
Provided is a method for producing a copolymer emulsion, which becomes the emulsion-type pressure-sensitive adhesive of the present invention, which is polymerized in the presence of a polymerization initiator.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION General formula (1) which is a monomer (a)
R ^{2 of} an alkyl (meth)acrylic acid ester represented by
Is a linear or branched alkyl group having 4 to 16 carbon atoms, and from the viewpoint of improving the adhesiveness to a non-polar material such as polyolefin, the number of carbon atoms of R ² is preferably 8 or more, and the low temperature adhesiveness From the viewpoint, the number of carbon atoms of R ² is 16 or less. R
^The number of carbon atoms of ² is preferably 8 to 16, more preferably 8 to 14, and particularly preferably 8 to 12. Examples of the monomer (a) include butyl (meth)acrylate,
Hexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylic acid (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, (meth) Examples thereof include isotridecyl acrylate, tetradecyl (meth)acrylate, and hexadecyl (meth)acrylate. These alkyl (meth)acrylic acid esters are
Used alone or as a mixture of these alkyl (meth)acrylic acid esters.

The proportion of the monomer (a) in the monomer mixture is from 10 to 99.9% by weight, preferably from 30 to 99.9% by weight, more preferably from 50 to 9 from the viewpoint of improving the adhesive strength.
It is 9.9% by weight, and more preferably 70 to 99.9% by weight.

The monomer (b) is a monomer having both a functional group that causes crosslinking by heat or an acid catalyst and a radically polymerizable double bond group. The number of alkyl carbon atoms of the alkoxyalkyl group is 6 or less, preferably 4 or less, from the viewpoint of enhancing the crosslinking reactivity and improving the peeling property. Examples of the monomer (b) include N-hydroxymethyl(meth)acrylamide, N-hydroxymethylitaconamide, N,
N'-dihydroxymethylitaconamide, N-hydroxymethylcrotonamide, N,N'-dihydroxymethylcrotonamide, N-hydroxyfumaramide,
Examples thereof include N,N′-dihydroxymethyl fumaramide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide and the like. In aqueous polymerization, N
Polymerization stability is better when a monomer having an N-alkoxyalkyl group is used than a monomer having a -hydroxyalkyl group, and N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth) Most preferred is the use of acrylamide, N-butoxymethyl(meth)acrylamide. The monomer (b) is more hydrophilic than the monomer (a). Therefore, it is considered that in the polymerization for obtaining the polymer emulsion, the polymerization is not performed uniformly, and most of them are copolymerized in a form localized on the surface of the polymer particles. The N-hydroxyalkyl group or N-alkoxyalkyl group existing on the surface of the polymer particles will perform a crosslinking reaction in the drying step at the time of producing the pressure-sensitive adhesive sheet, and will play a role of increasing the bond between the polymer particles. Further, the N-hydroxyalkyl group or N-alkoxyalkyl group present on the surface of the polymer particles undergoes a cross-linking reaction under the influence of heat and acid of the polymerization system during the polymerization reaction, and a part thereof does not dissolve in the solvent. Generate minutes. That is, in the polymer particles of the emulsion pressure-sensitive adhesive of the present invention, the core portion has an uncrosslinked polymer, the shell portion has a crosslinked structure polymer, and the surface of the polymer particles has a crosslinkable N-hydroxyalkyl group or N-alkoxyalkyl group. It has a structure, and it is presumed that the excellent release property of the emulsion-type pressure-sensitive adhesive of the present invention is based on this characteristic polymer particle structure.

From the above, the copolymerization amount of the monomer (b) has a great influence on the adhesive force and the releasability. In the present invention, the proportion of the monomer (b) in the monomer mixture is 0.1% by weight or more from the viewpoint of preventing contamination of the adherend, and
From the viewpoint of improving the adhesive strength and economical efficiency, it is 10% by weight or less, preferably 0.1 to 5% by weight, and more preferably 0.1.
It is 1 to 3% by weight.

The copolymer of the present invention can be obtained by further copolymerizing the above-mentioned monomers (a) and (b) with a monomer (c) copolymerizable therewith. Monomer (c)
Examples include (meth)acrylic acid lower alkyl esters such as methyl acrylate, (meth)acrylic acid hydroxyalkyl esters such as hydroxyethyl methacrylate, and long-chain alkyl (meth)acrylic acid having an alkyl group having 17 or more carbon atoms. Ester, vinyl ester such as vinyl acetate, aromatic vinyl such as styrene, nitrile monomer such as acrylonitrile, amide monomer not included in the above monomer (b) such as acrylamide, (meth)acrylic acid And other carboxylic acid-based monomers. Of these, vinyl esters such as (meth)acrylic acid lower alkyl ester, (meth)acrylic acid hydroxyalkyl ester and vinyl acetate are preferable. From the viewpoint of improving tackiness, the monomer (c) is 89.9% by weight in the monomer mixture.
Or less, preferably 50% by weight or less, more preferably 30%
It is less than or equal to weight %. Furthermore, if necessary, an internal crosslinkable monomer such as divinylbenzene or ethylene glycol dimethacrylate may be used in an amount of 2% by weight or less based on the total amount of the monomers. Further, of the above-mentioned monomer (c), it is preferable to use the α,β-unsaturated carboxylic acid monomer in the range of 0.2 to 5% by weight in the monomer mixture.

The tetrahydrofuran (hereinafter referred to as THF) soluble content of the copolymer of the present invention is preferably 2% by weight or more from the viewpoint of improving the adhesive strength and 50% by weight or less from the viewpoint of improving the releasability. Further, the weight average molecular weight of the THF-soluble component is preferably 700,000 or less from the viewpoint of improving the adhesive strength, and 50,000 or more from the viewpoint of improving releasability. For re-peeling, the THF soluble content is 4
When the content of the THF-soluble component is 0% by weight or less, the weight-average molecular weight is 10
10,000 or more is preferable, and the THF soluble content is 30% by weight or less,
The weight average molecular weight of the THF-soluble component is more preferably 200,000 or more. For strong adhesion, the THF-soluble content is preferably 5% by weight or more, the THF-soluble content has a weight average molecular weight of 600,000 or less, and the THF-soluble content is 10% by weight or more.
The weight average molecular weight of the soluble component is more preferably 500,000 or less.
As a well-balanced pressure-sensitive adhesive having both adhesiveness and removability, the THF-soluble content is 5% by weight or more and 40% by weight or less, and the THF-soluble content has a weight average molecular weight of 100,000 or more and 600,000 or less. Those are preferably used.

The THF-soluble content of the emulsion-type pressure-sensitive adhesive and its weight-average molecular weight are the copolymerization amount of the monomer (b), the use of a radical chain transfer agent, the copolymerization of carboxylic acid-based monomers, and the initiation of polymerization. It can be easily controlled by means such as selection of agents. That is, the monomer (b) is involved in the formation of the gel component, and the amount of the gel component formed can be adjusted by the amount used.
Further, the crosslinking reaction of the N-hydroxyalkyl group or the N-alkoxyalkyl group is promoted by an acid catalyst, and the amount of gel component can be adjusted by copolymerizing the carboxylic acid-based monomer and adjusting the pH of the polymerization system. .. Furthermore, the use of a hydrogen-absorptive crosslinkable polymerization initiator such as benzoyl peroxide can increase the gel content. Further, when a radical chain transfer agent is added to the polymerization system, the molecular weight of the polymer can be lowered, and the addition amount thereof can adjust the weight average molecular weight of the THF-soluble component.

Next, the components (a)-(b) or (a)-
A method for obtaining an emulsion of the copolymer of the present invention comprising the component (c) will be described. As a method for obtaining the copolymer emulsion according to the present invention, a known polymerization method can be applied. However, in the case of a monomer system containing a large amount of poorly water-soluble long-chain alkyl (meth)acrylic acid ester, an emulsifier or an emulsifying dispersant is used as an aqueous solution to atomize the monomer, and then in the presence of a polymerization initiator. The method of copolymerization is desirable. In a usual emulsion polymerization method in which micelles are used as a place of polymerization, it is difficult to obtain a stable polymer emulsion when a poorly water-soluble long-chain alkyl (meth)acrylic acid ester is used as a raw material. According to the above, a polymer emulsion having good stability can be obtained. An example of a method in which a monomer is made into fine particles using an emulsifying dispersant aqueous solution and then copolymerization is performed in the presence of a polymerization initiator will be described below.

As the emulsifying dispersant used in the production of the emulsion-type pressure-sensitive adhesive of the present invention, anionic and nonionic surfactants can be used. For example, it is described on page 4 of JP-A-6-192341. The emulsifiers that have been used are mentioned. Further, the polymerizable emulsifying dispersant can be used alone or in combination with the above emulsifying dispersants. When a polymerizable emulsifying dispersant is used, water resistance and moisture resistance can be improved as compared with a normal emulsifying dispersant. The polymerizable emulsifying dispersant that can be used in the present invention is an emulsifying dispersant having a radical-polymerizable double bond in the molecule. As the polymerizable emulsifying dispersant, for example, an interface having an allyl group, a (meth)acrylic acid group, a styrene group, an isopropenyl group in the molecule as a polymerizable group as described in JP-A-5-255411, page 2 Activators can be used as the polymerizable emulsifying dispersants of the present invention.

The production of the emulsion pressure-sensitive adhesive can be divided into a step of emulsifying and dispersing a monomer and a step of polymerizing. In the step of emulsifying and dispersing the monomer, the monomer mixture and the emulsifier aqueous solution are mixed, and the volume average particle diameter of the monomer fine particles is emulsified to 0.1 to 5 μm, preferably 0.1 to 2 μm using an emulsifying machine. Spread. The use ratio of the monomer and the emulsifier aqueous solution is not limited, but if the monomer concentration is less than 5%, there is a problem in economic efficiency, and if the monomer concentration exceeds 80%, the emulsion viscosity becomes high. Since the production becomes difficult for the reason, the total amount of the monomers is 5 to 80% by weight, preferably 3 to the total polymerization system.
It is desirable to be 0 to 60% by weight. The emulsifier used in the present invention has a volume average particle size of the monomer particles of 0.1 to 5
Any model can be used as long as it can be made in μm. Examples of the emulsifier that can be used in the present invention include an ultrasonic homogenizer, a homomixer, a milder, an attritor, a (super)high pressure homogenizer, and a colloid mill.

In the polymerization reaction step, the emulsion of the above-mentioned monomer is charged into a polymerization vessel equipped with a stirrer, a polymerization initiator is added thereto, and the mixture is heated to an appropriate polymerization temperature to start the polymerization reaction. It At this time, it is desirable to replace the polymerization system with an inert gas such as nitrogen in order to prevent the polymerization inhibition effect by oxygen. The polymerization initiator used in the polymerization reaction step,
Both a water-soluble polymerization initiator and an oil-soluble polymerization initiator can be used. In the case of a water-soluble initiator, it is desirable to add it immediately before the polymerization reaction, and in the case of an oil-soluble polymerization initiator, it is desirable to add and dissolve it in the monomer before emulsification. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, 2,2′-azobis(2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanovaleric acid and the like. And a redox polymerization initiator such as t-butyl hydroperoxide/ascorbic acid. Examples of the oil-soluble polymerization initiator include organic peroxides such as benzoyl peroxide and lauroyl peroxide, 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobis(2,4-). Examples thereof include oil-soluble azo polymerization initiators such as dimethyl valeronitrile). Although the amount of the polymerization initiator used is not limited, it is preferably 0.01 to 5% by weight, and more preferably 0.02 to 1% by weight, based on all the monomers. When a large amount of the polymerization initiator is used, the polymerization rate increases, but the polymer molecular weight tends to decrease. Further, when a polymerization initiator having a hydrogen abstraction cross-linking property such as benzoyl peroxide is used, the gel content tends to be higher than that of an azo-based initiator or the like. Therefore, since the polymerization initiator affects both the polymerization rate and the polymer structure, it is necessary to select a type suitable for the polymerization system and to adjust the amount to be used appropriately.

In the pressure-sensitive adhesive of the present invention, the weight average molecular weight of the THF-soluble component is preferably 5 to 700,000, but a radical chain transfer agent can be used for the purpose of adjusting the molecular weight to this range. Examples of the radical chain transfer agent that can be used in the present invention include alkyl mercaptans having 3 to 32 carbon atoms, such as (iso)butyl mercaptan and (iso).
Octyl mercaptan, (iso)decyl mercaptan,
Examples thereof include alkyl mercaptans such as (iso)dodecyl mercaptan. In addition, disulfides such as isopropylxanthogen disulfide can be used. When the amount of the radical chain transfer agent used is 1% by weight or less based on the total amount of the monomers, the peelability is good even though the adhesive strength is high. Therefore, the amount of radical chain transfer agent used is preferably 1% by weight or less, and more preferably 0.3% by weight or less, based on the total monomer system. The polymerization temperature varies depending on the composition of the monomer and the kind of the polymerization initiator, but is about 40 to 90.
A range of °C is suitable. Further, the polymerization time varies depending on the monomer, the polymerization initiator and the polymerization temperature, but it is generally 1 to 10
Time is appropriate. The particle size of the polymer emulsion obtained through the above emulsification step and polymerization step is 0.1 to 2 μm.
m and the stability is good.

Examples of the pressure-sensitive adhesive product of the present invention include pressure-sensitive adhesive sheets such as surface protective films, masking tapes for painting, pressure-sensitive adhesive tapes and pressure-sensitive adhesive labels. These pressure-sensitive adhesive sheets are produced by applying an emulsion-type pressure-sensitive adhesive to one or both surfaces of various base material sheets and drying it to form a pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer varies depending on the application, but is 1 to 1
It is preferably set to 00 μm. As the base material sheet, polyethylene resin, polypropylene resin, polyvinyl chloride resin, and polyester resin are preferably used.
The thickness of these base material sheets may be appropriately determined according to the application.

[0019]

EXAMPLES In the following examples, the average particle size is HOR.
The volume average particle diameter was measured using an IBA particle size analyzer (LA-910 type). The method for measuring the THF-soluble content will be described below.

(1) Method for measuring THF-soluble content Teflon flat plate (TERAOKA flat plate: 25 ml in volume:
0.5 g of the adhesive polymer emulsion was placed in a model number CW16025) and left standing in a room at 23° C. and a humidity of 60% RH for 48 hours to form a polymer film. Next, 0.2 g of the above coating was precisely weighed into a 100 ml screw tube (Maru M No. 7), 80 ml of THF was added thereto, and 23-2
Shaker (TAITEC INCUB) at a temperature of 6℃
ATOR: Model number WB-III) 2 on the speed scale 7
The THF-soluble polymer was extracted by shaking for 4 hours. Then, the mixture was filtered through a 200-mesh stainless steel wire net to separate and remove the gel component, the extract solution was evaporated to dryness, and the weight of the residual polymer was measured to determine the weight of the THF-soluble polymer. The THF-soluble matter was obtained by the following calculation formula.

[0021]

[Equation 1]

The molecular weight of the THF-soluble component is the following GPC.
Weight average molecular weight (polystyrene conversion) measured by analytical method
Expressed as -GPC analysis method Column: GMHXL (manufactured by Tosoh: 7.8 mm x 300 m)
m) Two direct connection Eluent: 50 μmol-CH ₃ COOH/THF (flow rate: 1 ml/min) Detector: RI Sample concentration: 2 mg/ml, injection amount: 100 μl.

(2) Method for preparing pressure-sensitive adhesive sheet A biaxially stretched polypropylene film (Toray: Trefan BO, thickness 50 μm) is used on the corona-treated surface of an emulsion type coating machine (Multicoater, M200) manufactured by Hirano Techseed. The adhesive has a thickness of 25μ after the adhesive layer is dried.
m and then dried at 100° C. for 30 seconds, and then a release film made of polyester resin (San-A Kaken: ID-8, thickness 38 μm) and a laminated adhesive sheet were prepared.

(3) Adhesive Sheet Evaluation Method The adhesive sheet was evaluated according to JIS Z 0237-991 under the following conditions.

Measurement of initial adhesive strength In the 180-degree peeling method, a mirror-finished stainless steel plate (SUS304/#800 polishing) was used as a test plate and
Stick a piece of adhesive sheet of mm width, 23℃/65%RH
After being left for 30 minutes under the conditions of, the 180 degree peel strength (peel rate: 300 mm/min) was measured.

Measurement of holding force As a test plate, a mirror surface stainless steel plate (SUS304/#80)
25 mm width of the adhesive sheet piece using
Laminate so that the area of mx 25 mm touches, and
A load of g was applied, and after 3 hours at 70° C., the presence or absence of peeling and the presence or absence of deviation were observed. Those that did not peel off or shift were marked as "○", and those that peeled off were marked as "x". In addition, the deviation width was measured for those in which deviation was observed.

Low-speed peelability In the 180-degree peeling method, a mirror surface stainless plate (SUS304/#800 polishing) was used as a test plate,
Sticking a piece of adhesive sheet with mm width, temperature 60℃/80%
After storing for 7 days under the condition of RH, it was stored at 23°C/65
After allowing to cool for 30 minutes under the condition of %RH, the 180-degree peel strength (peel rate: 0.3 m/min) was measured.
Further, in this peel strength measurement, the state of contamination of the peeled surface of the mirror-finished stainless steel plate was measured with the naked eye, "○" when there was no contamination, "△" when there was cloudiness, and when residual adhesive was observed. It was evaluated as "x".

High Speed Peelability 180 degree peel strength was measured in the same manner as in the above low speed peel test except that the peel speed was changed to 30 m/min.
In addition, similarly, the state of contamination of the mirror-finished stainless steel plate was observed.

Example 1 Lauryl methacrylate 111.2 in a 1 liter container
g, 2-ethylhexyl acrylate 280 g, acrylic acid 6 g, n-butoxymethyl acrylamide 2.8
g, n-dodecyl mercaptan 0.08 g, and benzoyl peroxide 1.2 g were added and dissolved uniformly, and an effective ingredient 1.8% Latemur S-180 (Kao Corporation: polymerizable surfactant) aqueous solution was added. Using a high-pressure homogenizer (made by Izumi Food Machinery) with 340g, add 5
It was treated for minutes to obtain an emulsion having a volume average particle size of 0.38 μm.

This emulsion was transferred to a 1-liter glass reaction vessel and purged with nitrogen gas, and then stirred at 85° C.
And then at the same temperature for 4 minutes to complete the polymerization.
Aged for time to obtain a polymer emulsion. The average particle size of this polymer emulsion was 0.46 μm. Table 1 shows the analytical values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the same.

Example 2 120 g of lauryl methacrylate in a 1 liter container,
Hexadecyl methacrylate 40 g, 2-ethylhexyl acrylate 232 g, acrylic acid 6 g, n-butoxymethyl acrylamide 2.0 g, n-dodecyl mercaptan 0.06 g, benzoyl peroxide 1.2.
g, and dissolved uniformly and mixed with 340 g of an aqueous solution of Neoperex F-25 (manufactured by Kao Corporation: surfactant) containing 1.8% of the active ingredient, an ultrasonic high-pressure homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). ) For 15 minutes to obtain an emulsion having a volume average particle size of 0.45 μm. Thereafter, polymerization was carried out in the same manner as in Example 1, and the average particle size was 0.57 μm.
A polymer emulsion of Table 1 shows the analytical values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the same.

Example 3 340 g of lauryl methacrylate in a 1 liter container,
51 g of n-butyl acrylate, 6 g of methacrylic acid, n
-Methoxymethyl acrylamide 2.8 g, divinylbenzene 0.2 g, 2,2'-azobis(2-methylbutyronitrile) 1.2 g were added and dissolved uniformly, to which the active ingredient 1.8% Aqualon HS was added. -10 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.: polymerizable surfactant) aqueous solution (340 g) was mixed with a high-pressure homogenizer (made by Izumi Food Machinery Co., Ltd.) to obtain 5
It was treated for minutes to obtain an emulsion having a volume average particle size of 0.48 μm. Then, polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was changed to 75° C. to obtain a polymer emulsion having an average particle size of 0.47 μm. Table 1 shows the analysis values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the analysis value.
Shown in.

Example 4 Lauryl methacrylate 391.2 in a 1 liter container
g, 6 g of acrylic acid, 2.8 g of n-butoxymethyl acrylamide, 0.06 g of n-dodecyl mercaptan and 1.2 g of benzoyl peroxide were added and uniformly dissolved, and to this, 1.8% of the active ingredient, Latemur S-180. (Kao Corporation: Polymerizable surfactant) A mixture of 300 g of an aqueous solution was treated with a high-pressure homogenizer (made by Izumi Food Machinery) for 5 minutes to give a volume average particle diameter of 0.37 μm.
To obtain an emulsion. 40 g of the Latemur S-180 aqueous solution containing 1.8% of the active ingredient was placed in a glass reaction vessel similar to that used in Example 1, the atmosphere was replaced with nitrogen gas, and the temperature was raised to 85° C. with stirring. Then, while stirring at the same temperature, 2
It takes time to drop and polymerize. Furthermore, in order to complete the polymerization, it was aged at the same temperature for 4 hours, and the average particle size was 0.45 μm.
A polymer emulsion of Table 1 shows the analytical values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the same.

Example 5 200 g of lauryl methacrylate in a 1 liter container,
171.2 g of 2-ethylhexyl acrylate, 20 g of methyl methacrylate, 6 g of acrylic acid, 2.8 g of n-butoxymethyl acrylamide, 0.08 g of n-dodecyl mercaptan and 1.2 g of benzoyl peroxide were added and uniformly dissolved, effective for this. A high-pressure homogenizer (manufactured by Izumi Food Machinery) was prepared by mixing a mixture of 170 g of an aqueous solution of 1.8% latemulrebenol WZ (manufactured by Kao Corporation: a surfactant) and 170 g of an aqueous solution of 1.8% of an active ingredient Emulgen 920. For 5 minutes to obtain an emulsion having a volume average particle size of 0.45 μm. Thereafter, polymerization was carried out in the same manner as in Example 1 to obtain a polymer emulsion having an average particle size of 0.51 μm. Table 1 shows the analysis values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the analysis value.
Shown in.

Comparative Example 1 394 g of n-butyl acrylate in a 1 liter container,
6 g of acrylic acid was added and dissolved uniformly, and 1% of active ingredient Rebenol WZ (Kao Corporation: surfactant) was added to this.
A mixture of 500 g of an aqueous solution and 1.2 g of ammonium persulfate was treated with a homomixer (manufactured by Tokushu Kikai Kogyo) for 5 minutes to obtain an emulsion having a volume average particle size of 18.5 μm. In a glass reaction vessel similar to that used in Example 1, an aqueous solution of 1% Lebenol WZ (manufactured by Kao Corporation: surfactant) 10% of the active ingredient was used.
After adding 0 g and replacing with nitrogen gas, 70°C with stirring.
The temperature rises to. Thereafter, the above emulsion is added dropwise for 2 hours with stirring at the same temperature to carry out polymerization. Aged at the same temperature for 4 hours to complete the polymerization, and the average particle size is 0.25 μm.
A polymer emulsion of Table 1 shows the analytical values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the same.

Comparative Example 2 292 g of n-butyl acrylate in a 1 liter container,
2 Ethylhexyl acrylate 100 g, divinylbenzene 2 g, acrylic acid 6 g were added and dissolved uniformly, and an aqueous solution of 1% active ingredient Aqualon HS-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.: polymerizable surfactant) 500 g, potassium persulfate A mixture of 1.2 g was treated with a homomixer (made by Tokushu Kikai Kogyo) for 5 minutes to give a volume average particle diameter of 25.5 μm.
To obtain an emulsion. Below, Rebenol WZ with 1% active ingredient
Polymerization was performed in the same manner as in Comparative Example 1 except that the aqueous solution was changed to an aqueous solution of 1% active ingredient Aqualon HS-10 to obtain a polymer emulsion having an average particle size of 0.23 μm. Table 1 shows the analytical values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the same.

Comparative Example 3 In a 1-liter container, 150 g of 2-ethylhexyl acrylate, 6 g of acrylic acid and 2 n-butyl acrylate were used.
44 g and benzoyl peroxide 1.2 g were added and dissolved uniformly, and an aqueous solution of 1.8% Neoperex F-25 (manufactured by Kao Corporation: surfactant) aqueous solution 34 was added thereto.
The mixture containing 0 g was treated with an ultrasonic high-pressure homogenizer (manufactured by Nippon Seiki Seisakusho Ltd.) for 15 minutes to obtain an emulsion having a volume average particle size of 0.41 μm. Then, polymerization was carried out in the same manner as in Example 1 to obtain a polymer emulsion having an average particle size of 0.610 μm. Table 1 shows the analytical values of this polymer emulsion and the evaluation of the pressure-sensitive adhesive sheet obtained using the same.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION According to the present invention, an aqueous emulsion type pressure sensitive adhesive having excellent releasability and pressure sensitive adhesive products such as pressure sensitive adhesive sheets using the same are provided. The pressure-sensitive adhesive product of the present invention has a pressure-sensitive adhesive force suitable for various uses, and the pressure-sensitive adhesive force does not change with time even when stored under high temperature or high humidity, and influences the peeling speed at the time of peeling. However, it can be easily peeled off, and the adherend does not remain or stain on the adherend.

The pressure-sensitive adhesive of the present invention is used for temporarily adhering to pressure-sensitive adhesive sheets such as pressure-sensitive adhesive labels and pressure-sensitive adhesive tapes, specifically metal plates such as stainless steel plates, aluminum plates and steel plates, and resin plates such as ABS resin. It can be used for surface protection film, masking tape for painting, adhesive tape for packaging, etc.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Doi 1334 Minato Minato, Wakayama City, Wakayama Prefecture F-term in the research institute of Kao Corporation (reference) 4J004 AA10 AB01 CA04 CA05 CA06 CC02 EA05 FA01 FA04 4J040 DF041 DF051 GA05 GA07 GA08 GA13 GA22 JA03 JA09 JB09 KA38 LA01 LA03 LA06 QA01

Claims (5)

[Claims] 1. A monomer having (a) 10-99.9% by weight of an alkyl(meth)acrylate represented by the following general formula (1) and (b) an N-hydroxyalkyl group or an N-alkoxyalkyl group. An emulsion-type pressure-sensitive adhesive comprising an emulsion of a copolymer obtained from a monomer mixture containing 0.1 to 10% by weight. ^{_{CH 2 = C (R 1)}} COOR 2 (1) [wherein, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 4 to 16 carbon atoms. ] 2. The emulsion-type pressure-sensitive adhesive according to claim 1, wherein the monomer mixture further contains an α,β-unsaturated carboxylic acid-based monomer component in an amount of 0.2 to 5% by weight. 3. The emulsion-type pressure-sensitive adhesive according to claim 1, wherein the copolymer has a tetrahydrofuran-soluble content of 2 to 50% by weight and a tetrahydrofuran-soluble content of 50,000 to 700,000. 4. A monomer having (a) 10-99.9% by weight of an alkyl(meth)acrylate represented by the following general formula (1) and (b) an N-hydroxyalkyl group or an N-alkoxyalkyl group. In the presence of a polymerization initiator, a monomer mixture containing 0.1 to 10% by weight is emulsified and dispersed in water in the presence of an emulsifier to reduce the volume average particle diameter to 0.1 to 5 μm. The method for producing a copolymer emulsion which becomes the emulsion-type pressure-sensitive adhesive according to any one of claims 1 to 3, which is polymerized. ^{_{CH 2 = C (R 1)}} COOR 2 (1) [wherein, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 4 to 16 carbon atoms. ] 5. A substrate and a substrate formed on the substrate.
An adhesive product having an adhesive layer made of the emulsion-type adhesive according to any one of 3 to 3.