JP3535780B2 - Emulsion for pressure sensitive adhesive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emulsion for pressure-sensitive adhesives, which exhibits a strong adhesive force even to a polyolefin having poor adhesion, has excellent water resistance, and has a high cohesive force.

[0002]

2. Description of the Related Art In recent years, from the viewpoints of environmental protection, safety of working environment, resource saving, cost, etc., the pressure sensitive adhesive is supplied from a solvent type (using an organic solvent as a solvent) to a solventless type. The shift to molds (those that do not use organic solvents) is becoming a major trend. From the viewpoint of versatility and workability, an emulsion-type pressure-sensitive adhesive is particularly preferably used among solventless types. In such a pressure-sensitive adhesive emulsion, a dispersant such as an emulsifier is required to disperse the water-insoluble pressure-sensitive adhesive polymer in an aqueous medium, and since the dispersant is a water-soluble substance, There is a problem that the pressure-sensitive adhesive film has poor water resistance.

The applicant of the present invention blends a compound capable of chemically bonding with a dispersant into an emulsion for pressure-sensitive adhesives, and after forming a film, reacts a carboxyl group in the dispersant with the above compound to thereby make the dispersant hydrophilic. And improved the water resistance of pressure-sensitive adhesive products (International Publication WO
96/29373).

[0004]

The pressure-sensitive adhesive product obtained from the above-mentioned emulsion for pressure-sensitive adhesive exhibits good water resistance, but recently, strong adhesive force, adhesiveness to polyolefin, and high-temperature cohesive force. It has been demanded to further improve the adhesive properties such as the above, and further studies have become necessary. As such an examination method, in addition to the method of changing the copolymer composition of the pressure-sensitive adhesive polymer, there is a method of adding an adhesion modifier such as a tackifier to the pressure-sensitive adhesive.
However, most of the tackifiers are oily, and in order to be blended into the pressure-sensitive adhesive emulsion, the tackifier must be made into an aqueous dispersion using a large amount of emulsifier,
It has been a cause of reducing the water resistance of pressure-sensitive adhesive products.

Therefore, in the present invention, an emulsion for pressure-sensitive adhesives, which exhibits good water resistance and is capable of producing a pressure-sensitive adhesive product excellent in adhesive properties such as strong adhesive force, adhesiveness to polyolefin, and high-temperature cohesive force, etc. It was listed as an issue.

[0006]

The emulsion for pressure-sensitive adhesives of the present invention has a glass transition temperature of -80 to -20 ° C, a weight average molecular weight of 150,000 or more, and an acid value of 30 or less due to a carboxyl group. Adhesive polymer (A) containing a carboxyl group having a weight average molecular weight of 100,000 or less, an acid value of 190 or more due to a carboxyl group before alkalization, and a part or all of the carboxyl group being an alkali salt A rosin derivative (B), a compound (C) having a weight average molecular weight of 100,000 or less, having no carboxyl group, and having at least one functional group reactive with a carboxyl group in one molecule is essential. An emulsion containing as a component, wherein the total of the pressure-sensitive adhesive polymer (A) and the rosin derivative (B) contained in the emulsion is 100% by mass. When the rosin derivative (B) is 2
The amount of the functional group contained in the compound (C) is 0.05 to 10 equivalents relative to 1 equivalent of the carboxyl group contained in the rosin derivative (B). It has a summary where it is included.

The above emulsion may further contain an emulsifier having no reactivity with the monomer for the pressure-sensitive adhesive polymer (A). In addition, the above compound (C)
Is preferably an aziridinyl group-containing compound and / or polyglycidyl amine.

The emulsion of the present invention is prepared by emulsion polymerization using an emulsifier having no reactivity with the monomer for the pressure-sensitive adhesive polymer (A) and / or an emulsifier having an ethylenically unsaturated double bond. After obtaining an emulsion of the adhesive polymer (A), an alkaline aqueous solution is added to the obtained emulsion to give an alkaline emulsion. In this alkaline emulsion, the weight average molecular weight is 100,000 or less, and the acid value by the carboxyl group is 190. It is preferably obtained by adding the carboxyl group-containing rosin derivative (B ′) described above and further adding the compound (C).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive emulsion of the present invention comprises a pressure-sensitive adhesive polymer (A), a carboxyl group-containing rosin derivative (B) and a compound (C) as essential components. The most important feature is that the carboxyl group-containing rosin derivative (B) is stably present in the emulsion in the form of an alkali salt, and after forming a film, the rosin derivative (B)
By chemically reacting the carboxyl group of the compound (C) with the compound (C) to lose its hydrophilicity, the adhesive property improving effect of the rosin derivative (B) is exerted while maintaining good water resistance. Is that we were able to improve the BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. When simply referred to as a "polymer," it includes not only a homopolymer but also a copolymer and a ternary or higher copolymer.

First, the pressure-sensitive adhesive polymer (A) which is the first essential component is a polymer which generally exhibits pressure-sensitive adhesiveness in the temperature range in which the pressure-sensitive adhesive product is used. Normal,
The pressure-sensitive adhesive polymer (A) is not dissolved in water and an aqueous alkaline solution but is emulsified with a water-soluble emulsifier to form an aqueous dispersion. When emulsion polymerization of the pressure-sensitive adhesive polymer (A) is performed using a reactive emulsifier having reactivity with a monomer for the polymer (A), such as an emulsifier having an ethylenically unsaturated double bond, Pressure-sensitive adhesive polymer (A)
The reactive emulsifier is chemically bonded to the molecular chain of to obtain a polymer (A) incorporating the reactive emulsifier. As a result, this pressure-sensitive adhesive polymer (A) becomes an emulsion by itself without the aid of other emulsifiers. In the present invention, such a pressure-sensitive adhesive polymer (A) can also be preferably used.

As the pressure-sensitive adhesive polymer (A), one having a glass transition temperature (Tg) of -80 to -20 ° C is used. A polymer having a Tg of −20 ° C. or higher may not exhibit pressure-sensitive adhesiveness at room temperature, so the above-mentioned Tg requirement is set as a standard for showing the pressure-sensitive adhesiveness of the polymer. However, T
When g is lower than −80 ° C., the high temperature cohesive force tends to decrease, which is not preferable. Tg (K) is “POLY
MER HANDBOOK 3rd Edition "(John Wiley & S
ons, Inc.) Tg of each homopolymer described in
It can be easily calculated by the following formula based on (K), or by DSC (differential scanning calorimeter) or DTA (differential thermal analyzer).

[0012]

[Equation 1]

Where W _n ; mass fraction of each monomer Tg _n ; Tg (K) of homopolymer of each monomer

The pressure-sensitive adhesive polymer (A) has a weight average molecular weight (Mw) of 150,000 or more. Mw is 15
This is because if it is less than 10,000, the adhesive property will be poor. The molecular weight is a value in terms of polystyrene measured by gel permeation chromatography (GPC) (both Mw and Mn, the same applies hereinafter). However, a polymer with a large molecular weight (Mw of about 1.5 million or more) will not dissolve in the solvent (THF; tetrahydrofuran) used for GPC measurement, and the molecular weight measurement itself by GPC will be impossible, so the exact Mw is unknown. However, in other words,
A polymer that does not dissolve in THF has an Mw of about 150.
Since it is clear that it is more than 10,000, it can be preferably used in the present invention. The method for evaluating the solubility at this time is as follows.

The pressure-sensitive adhesive polymer is appropriately sampled and its dry mass is measured (if the polymer is in a water dispersion state, it is measured after evaporating the water content).

The above dry polymer was mixed with 10 times the mass of THF.
And leave at room temperature to 40 ° C. for 24 hours with occasional stirring. Dissolution may be promoted by applying heat or ultrasonic waves.

After 24 hours, the mixture of the polymer and THF is filtered through a 300-mesh wire net, the residue left on the wire net is dried, and its mass is measured. This is shown as the insoluble matter and expressed as a percentage of the initial mass.

When the insoluble content is 50% by mass or more, TH
Judged to be insoluble in F, Mw of 1.5 million or more, and unmeasurable. When the insoluble content is less than 50% by mass, the molecular weight is measured by GPC using a solution of the soluble content.

As the pressure-sensitive adhesive polymer (A), one having an acid value (carboxyl group value) of 30 or less is used. This is because when the acid value exceeds 30, Tg often becomes higher than -20 ° C. Further, the compound (C) described later reacts with the carboxyl group in the polymer, and the polymer chains are crosslinked to reduce the adhesive strength as a pressure-sensitive adhesive, which is not preferable. The acid value is preferably 15 or less, more preferably 5 or less. In addition, the “acid value” of the present invention means that 1 g of a compound containing a carboxyl group is dissolved in a good solvent to obtain K
It is the value in mg of the KOH amount required when performing the neutralization titration with OH.

Specific examples of the pressure-sensitive adhesive polymer (A) include natural rubber and styrene-isoprene-styrene (SI).
S) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, rubber-based polymers such as synthetic rubbers, and polymers obtained by polymerizing monomers having an ethylenically unsaturated bond are preferable. In particular, from the viewpoint of adhesive properties, acrylic polymers having (meth) acrylic acid alkyl ester as a main constituent are preferable.

As the (meth) acrylic acid alkyl ester constituting the acrylic polymer, butyl (meth) acrylic acid, amyl (meth) acrylic acid, heptyl (meth) acrylic acid, 2-ethylhexyl (meth) acrylic acid, ( N-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate and the like having 4 to 12 carbon atoms. (Meth) acrylic acid alkyl ester having an alkyl group is preferable, and one or more of them can be used.

The acrylic polymer may be composed only of the above-mentioned (meth) acrylic acid alkyl ester, but may be copolymerized with other monomers. In that case, it is preferable to use the above-mentioned (meth) acrylic acid alkyl ester in an amount of 60% by mass or more based on the whole monomer from the viewpoint of adhesive properties.

Examples of other monomers include (meth)
Of acrylic acid, cycloalkyl (meth) acrylates, (meth) acrylic acid esters having an alkyl group having 3 or less carbon atoms, carboxyl group-containing (meth) acrylic acid esters, and 2-hydroxyethyl (meth) acrylate. Such as hydroxyl group-containing (meth) acrylic acid esters, styrene, aromatic unsaturated hydrocarbons such as α-methylstyrene, vinyl esters, vinyl ethers such as methyl vinyl ether, unsaturated cyanide compounds such as acrylonitrile, N- Isopropylacrylamide, N-vinylpyrrolidone, N, N-dimethylaminoethyl (meth)
Examples thereof include nitrogen atom-containing monomers such as acrylate.

The emulsion for pressure-sensitive adhesive of the present invention includes
The second essential component has a weight average molecular weight of 100,000 or less and an acid value of 1 before the alkalization due to the carboxyl group.
90 or more, and the carboxyl group-containing rosin derivative (B) in which some or all of the carboxyl groups are alkaline salts is contained. Hereinafter, for convenience, the carboxyl group-containing rosin derivative before being alkalized is referred to as a rosin derivative (B ′).

The "rosin derivative" used in the present invention means a rosin derived from pine, which is roughly classified into gum rosin, wood rosin, and tall oil rosin, which has been subjected to at least carboxylic acid modification. Rosin originally has a carboxyl group, but most rosins do not have an acid value of 190 or more unless carboxylic acid modification is performed. The carboxylic acid modification is carried out by reacting these rosins with a carboxylic acid such as acrylic acid, itaconic acid, fumaric acid or maleic acid to introduce a carboxyl group into the rosin. Of course, rosins such as hydrogenated rosin, disproportionated rosin, polymerized rosin and rosin ester also have an acid value of 190.
The above can be used in the present invention. Hydrogenated rosin is particularly useful for improving the weather resistance and yellowing resistance of pressure-sensitive adhesives.

Rosin derivatives are, as is well known, tackifiers. The adhesive strength improving effect of rosins improves the adhesive strength of the pressure-sensitive adhesive film obtained by forming the emulsion for pressure-sensitive adhesive into a film. Further, for example, when the emulsion is applied to a base material having a low surface energy such as a release treatment with a silicone resin, if the rosin derivative (B) is not included, the emulsion repels (without forming a coating film, The coating is difficult because of the large number of droplets), but the presence of the rosin derivative (B) avoids this inconvenience. This is because the rosin derivative (B), which has become an alkali salt, dissolves in the emulsion and reduces the dynamic surface tension of the emulsion.

The rosin derivative (B) present in the emulsion of the present invention is in a state of being dissolved in the aqueous phase of the alkaline emulsion due to its carboxyl group becoming an alkali salt, and the oil of the rosin derivative (B) itself. It is considered that the droplets are stabilized by the carboxyl group or the alkali base of the carboxyl group and exist as an emulsion. It is also considered that part of the alkali-salt rosin derivative (B) is present in a state of being adsorbed on the oil droplets of the pressure-sensitive adhesive polymer (A), and also as an emulsifier for stabilizing the polymer oil droplets. It is working. By combining these actions, the rosin derivative (B) is stably present in the emulsion. The term "alkaline" means a state of pH 7 or higher.

In order to obtain such a stable existing state, the acid value of the carboxyl group-containing rosin derivative (B ') before becoming an alkali salt must be 190 or more.
If the acid value of the rosin derivative (B ′) is not 190 or more, even if all the carboxyl groups of the rosin derivative (B ′) are alkali bases, the rosin derivative (B) cannot exist stably in the emulsion, which is preferable. Absent. That is, when the acid value of the rosin derivative is smaller than 190, a large amount of other emulsifier is required for stable dispersion in the emulsion, and the presence of this emulsifier deteriorates the water resistance of the pressure-sensitive adhesive film. In addition, unless the oil droplets of the rosin derivative are emulsified with another emulsifier, the rosin derivative particles are fused to each other in the emulsion, causing the problem of aggregation and sedimentation. The more preferable acid value of the rosin derivative (B ′) is 210 or more. This is because stability in water is improved. However, if a rosin derivative (B ′) having a too large acid value is used, the pressure-sensitive adhesive product may have poor water resistance even if the compound (C) loses hydrophilicity. The acid value of the derivative (B ') is 27
It is preferable to suppress it to 0 or less.

In order to allow the rosin derivative (B) to exist in the emulsion, after the emulsion of the pressure-sensitive adhesive polymer (A) is synthesized, an alkaline aqueous solution such as aqueous ammonia is added to make the emulsion alkaline, The method of adding the rosin derivative (B ') having an acid value of 190 or more to the emulsion is simple, and a part or all of the carboxyl groups of the added rosin derivative (B') becomes an alkali salt to form a rosin derivative (B '). ).

Since the rosin derivative (B) is stably present in the emulsion without the aid of the emulsifier as described above, the absolute amount of the emulsifier in the emulsion can be reduced. Further, after the emulsion is formed into a film, the alkali is scattered, so that a large number of carboxyl groups derived from the rosin derivative (B ′) will be present in the film, but in the present invention, these carboxyl groups are present. And the chemical reaction with the “functional group having reactivity with a carboxyl group” of the compound (C) described later, the carboxyl group can be consumed and its hydrophilicity can be lost, so that the water resistance of the film is reduced. It will be excellent.

The rosin derivative (B ') has a weight average molecular weight (Mw) of 100,000 or less. When it exceeds 100,000, when the compatibility between the rosin derivative (B ′) and the pressure-sensitive adhesive polymer (A) is not so good, the transparency of the obtained film may deteriorate. The Mw is preferably 10,000 or less, more preferably 6000, and even more preferably 3000 or less. If Mw is less than 100, the effect of modifying the adhesive strength is poor, so Mw is preferably 100 or more.

The rosin derivative (B ') preferably has a softening point of 200 ° C. or lower. A more preferable softening point range is 80 to 180 ° C. When a rosin derivative having a softening point lower than 80 ° C. is used, the cohesive force of the pressure-sensitive adhesive tends to be poor, but when it is expected that the pressure-sensitive adhesive product will be used at a relatively low temperature or rough surface When importance is attached to the adhesiveness, a rosin derivative having a softening point lower than 80 ° C. may be used.

The rosin derivative (B) is 2 when the total mass of the pressure-sensitive adhesive polymer (A) is 100% by mass.
-30 mass% (solid content) is present in the emulsion. If it is less than 2% by mass, the effect of modifying the adhesive property is poor, and if it exceeds 30% by mass, the balance of the adhesive property is lost, which is not preferable. A more preferable lower limit is 10% by mass and an upper limit is 23% by mass.

Third Embodiment of Emulsion for Pressure Sensitive Adhesive of the Present Invention
The essential component of does not have a carboxyl group, and,
The compound (C) has at least one functional group reactive with a carboxyl group in one molecule. This compound (C) chemically reacts the carboxyl group possessed by the rosin derivative (B ′) with the functional group of the compound (C) after forming a film of the emulsion for pressure-sensitive adhesives to give a rosin derivative (B ′). ) Is used to improve the water resistance of the film.

Therefore, the compound (C) must have at least one functional group capable of reacting with the carboxyl group of the rosin derivative (B '). Examples of such a functional group include a glycidyl group, an aziridinyl group, an oxazolinyl group, and an isocyanate group. However,
When the compound (C) having an isocyanate group is used, the isocyanate group reacts with water, which is the medium of the emulsion, and therefore it is preferable to use a compound in which the isocyanate group is blocked (blocked isocyanate). The compound (C) does not have a carboxyl group. When the compound (C) has a carboxyl group, it reacts with the above functional group of the compound (C).
This is because the compounds (C) react with each other to consume the functional group, and lose the reactivity with the carboxyl group required as the compound (C).

Since the compound (C) is necessary during the chemical reaction after forming the film as described above, it may be present in the emulsion before forming the film into the emulsion. The compound (C) may be water-soluble or oil-soluble. That is, it may be dissolved in the water phase of the emulsion, or may be dissolved in the oil droplets of the pressure-sensitive adhesive polymer (A) or the like. If the molecular weight is too high, the compound (C) becomes difficult to be dissolved in either water-soluble or oil-soluble form, so that a compound having a weight average molecular weight Mw of 100,000 or less is used. The Mw is more preferably 10,000 or less, still more preferably 5000 or less. This is because it is easily dissolved in the emulsion.

Specific examples of the compound (C) are as follows.

Glycidyl group-containing compound: Aliphatic oxides such as propylene oxide, aromatic oxides such as styrene oxide, alicyclic epoxides such as cyclohexene oxide, butyl glycidyl ether, "Epolite M-1230" (Kyoeisha Oil and Fat Chemistry) (Manufactured by Kogyo Co., Ltd.), aliphatic glycidyl ethers, phenyl glycidyl ether and other aromatic glycidyl ethers, glycidyl (meth) acrylate and other glycidyl esters, "T
Glycidylamine compounds such as ETRAD "series (manufactured by Mitsubishi Gas Chemical Co., Inc.), polyglycidyl ethers such as" Denacol "series (manufactured by Nagase), compounds containing aziridinyl group: aliphatic aziridines such as butylaziridine,
Aromatic aziridines such as phenylaziridine, 2- (1
-Aziridinyl) ethyl (meth) acrylate-containing unsaturated group-containing aziridines, "Chemite" series (manufactured by Nippon Shokubai Co., Ltd.), etc. Oxazolinyl group-containing compounds: aliphatic oxazolines such as 2-methyloxazoline, 2-phenyloxazoline, etc. Aromatic oxazolines, 2-isopropenyl-2-
Unsaturated group-containing oxazolines such as oxazoline, isocyanate group-containing compounds such as "Epocros" series (manufactured by Nippon Shokubai Co., Ltd.): tolylene diisocyanate (TDI), diphenylmethane diisocyanate (M
DI) and other general-purpose isocyanates, "Desmodur A
"P stable" and "death module CT stable"
(Manufactured by Sumitomo Bayer Co., Ltd.), block isocyanate-containing prepolymers such as "Desmo Cup 11", water-dispersible block isocyanates such as "Elastron" series, "Elastron BN" series (Daiichi Kogyo Seiyaku Co., Ltd.) Made) etc.

As the compound (C), among the compounds exemplified above, a glycidylamine compound (“TETRAD-
C ”,“ TETRAD-X ”; manufactured by Mitsubishi Gas Chemical Co., Inc. and compounds containing aziridinyl group (“ Chemite PZ-33 ”,
“Chemite DZ-22”; manufactured by Nippon Shokubai Co., Ltd.) is highly reactive and is preferably used.

The amount of the compound (C) includes that in which the functional group capable of reacting with the carboxyl group of the compound (C) is a carboxyl group (alkali salt) of the rosin derivative (B). Substantially, a rosin derivative (B ')
To 1 equivalent (which is a carboxyl group possessed by).
It is preferably in the range of 05 to 10 equivalents. 0.05
If the amount is less than the equivalent, the effect of improving the water resistance will be insufficient. A more preferable range is 0.1 to 5 equivalents.

The emulsion of the present invention may contain an emulsifier. Oil-soluble pressure-sensitive adhesive polymer (A)
This is because an emulsifier is required to stably disperse the above and maintain the emulsion state. The emulsifier is a compound having a hydrophilic group such as a sulfonate group or a carboxylate group and a hydrophobic group such as a hydrocarbon group and having an emulsifying ability. In the present invention, an emulsifier having no functional group capable of reacting with a carboxyl group is used. This is because the compound (C) having a functional group capable of reacting with a carboxyl group is present in the emulsion, and the emulsifier does not need to have such a functional group.

The emulsifier has a weight average molecular weight Mw of 1
Use less than 100,000. This is because the smaller the molecular weight, the higher the effect of lowering the surface tension of the emulsion and the better the coatability. From this viewpoint, the Mw of the emulsifier is preferably 10,000 or less, more preferably 3000 or less. The acid value of the emulsifier is preferably 185 or less from the viewpoint of water resistance.

The type of emulsifier is not particularly limited. For example, anions such as alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl diphenyl ether disulfonates, polyoxyethylene alkyl sulfate ester salts, polyoxyethylene alkylallyl sulfate ester salts, and naphthalene sulfonate formalin condensates. Type emulsifier; polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative,
Nonionic emulsifiers such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, and alkylalkanolamide can be used.

A carboxyl group-containing emulsifier may be used as the emulsifier. For example, fatty acid soap, N-acyl amino acid (salt), "MX-RLM" series (manufactured by Kao Corporation)
Alkyl ether carboxylic acids such as, acylated peptides,
Carboxybetaine type emulsifier, aminocarboxylic acid salt,
Polymeric polycarboxylic acid type emulsifiers such as "Latemur", "Demol", "Poise", "Homogenol" series (all manufactured by Kao Corporation), "RA-1020", "RA-1"
"RA-1000" such as "120", "RA-1820"
Series (Nippon Emulsifier), "SLB-12", "U"
LB-20 "," SL-20 "," SB-20 "," S
"T-2P", "IPU-22", etc. (all manufactured by Okamura Oil & Oil Co., Ltd.), "PDSA-DB", "PDSA-DA",
Examples thereof include basic acids having 8 to 28 carbon atoms such as "DSA" and "Sunbiter 150" (all manufactured by Sanyo Chemical Industry Co., Ltd.). This is because after the emulsion for pressure-sensitive adhesive is formed into a film, the functional group of the compound (C) reacts with the carboxyl group in the emulsifier to improve the water resistance.

Further, a dispersant disclosed in International Publication WO96 / 29373, which is a carboxyl group-containing oligomer type emulsifier excellent in emulsion stability during emulsion polymerization, may be used. This dispersant is a water-soluble or water-dispersible oligomer obtained by polymerizing a polymerizable monomer containing an unsaturated carboxylic acid (for example, acrylic acid) as an essential component in the presence of an alkylmercaptan having 6 to 18 carbon atoms. .

The above-mentioned emulsifier does not have reactivity with the monomer for the polymer (A) for pressure-sensitive adhesive unlike the reactive emulsifier described later. Therefore, in the emulsion, these emulsifiers are adsorbed to the pressure-sensitive adhesive polymer (A), but are not chemically bound. Further, these emulsifiers are different from any of the pressure-sensitive adhesive polymer (A), the rosin derivative (B) and the compound (C).

In order to improve water resistance, an emulsifier having reactivity with the monomer for the pressure-sensitive adhesive polymer (A), that is, a reactive emulsifier having an ethylenically unsaturated double bond is used. It is preferable. When emulsion polymerization is performed using a reactive emulsifier, it reacts with the ethylenically unsaturated double bond contained in the monomer for the pressure-sensitive adhesive polymer (A) and reacts with the molecular chain of the pressure-sensitive adhesive polymer (A). -Type emulsifier binds by polymerization reaction. As a result, the pressure-sensitive adhesive polymer (A) and the reactive emulsifier are integrated with each other, and the reactive emulsifier does not exist as a single molecule in the emulsion, so that the water resistance is not lowered.

Specific examples of the reactive emulsifier having a double bond are as follows. One or more of these may be used.

[0049]

[Chemical 1]

Allyl group-containing anion type represented by the above formula (where R is an alkyl group): For example, polyoxyethylene allyl glycidyl nonyl phenyl ether sulfate ester salt: As a commercial product, "Adecaria Soap S"
"E" series (manufactured by Asahi Denka Co., Ltd.), "Eleminol JS" series (manufactured by Sanyo Chemical Co., Ltd.), "Latemuru" series (manufactured by Kao Corporation), "H3390A" and "H3390B" (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), etc. There is.

Allyl group-containing nonionic type: for example, polyoxyethylene allyl glycidyl nonyl phenyl ether: Commercially available products include "Adecaria Soap NE" series (manufactured by Asahi Denka Co., Ltd.) and the like.

Allyl group-containing cation type: "RF-751" (manufactured by Nippon Emulsifier Co., Ltd.) is commercially available.

[0053]

[Chemical 2]

(Meth) acryloyl group-containing anion type represented by the above formula (where R is an alkyl group): Commercially available "Eleminol RS" series (manufactured by Sanyo Chemical Co., Ltd.), "Antox" series (manufactured by Nippon Emulsifier Co., Ltd.) Etc.

(Meth) acryloyl group-containing nonionic type: Commercially available products include "RMA-560" series (manufactured by Nippon Emulsifier Co., Ltd.).

Propenyl group (CH ₃ -CH = CH-)-containing anion type: For example, sulfuric acid ammonium salt of polyoxyethylene nonylpropenyl phenyl ether: As commercially available products, "AQUARON HS" series and "AQUARON BC" series (No. Manufactured by Ichigohyo Pharmaceutical Co., Ltd., etc.

Propenyl group-containing nonionic type: For example, polyoxyethylene nonylpropenyl phenyl ether: As a commercial item, there is "Aqualon RN series" (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

The emulsifier is used in the range of 0.5 to 10 parts by mass with respect to 100 parts by mass of the monomer for the pressure-sensitive adhesive polymer (A). You may mix and use the above-mentioned various emulsifiers.

The preferred method for producing the emulsion for pressure-sensitive adhesives of the present invention will be described below. The first method for producing the emulsion for pressure-sensitive adhesives of the present invention is the pressure-sensitive adhesive polymer (A) described above in the emulsion polymerization method using an emulsifier.
This is a method of polymerizing a monomer for use to make the obtained emulsion of the pressure-sensitive adhesive polymer (A) alkaline, and then adding the rosin derivative (B ′) and the compound (C) to this emulsion. After synthesizing the pressure-sensitive adhesive polymer (A),
This is a simple method because it can be used as an emulsion as it is. In the emulsion polymerization of the pressure-sensitive adhesive polymer (A), an emulsifier having no reactivity with the monomer for the pressure-sensitive adhesive polymer (A) and / or an emulsifier having an ethylenically unsaturated double bond is used. Then, the polymerization may be carried out under a normal condition using a known water-soluble polymerization initiator.

Since the rosin derivative (B ') has a large number of carboxyl groups (hydrophilic groups) and also has a lipophilic moiety derived from rosin, it also acts as an emulsifier. Therefore, a rosin derivative (B ′) corresponding to part or all of the amount of the rosin derivative (B) that should finally be present in the emulsion is added to the polymerization vessel from the beginning of emulsion polymerization,
It is possible to use together with an emulsifier. However, from the viewpoint of stability of emulsion polymerization and storage stability of emulsion, it has an emulsifier and / or an ethylenically unsaturated double bond that does not react with the monomer for the pressure-sensitive adhesive polymer (A) described above. Preference is given to using emulsifiers.

The conversion of the rosin derivative (B ') into the rosin derivative (B) by making the emulsion alkaline is
It may be carried out at any stage of emulsion polymerization. When the rosin derivative (B ') is added to the alkaline water while the pH of the aqueous medium for the polymerization is set to 7 or more, either before, during or after the emulsion polymerization, finally obtained. The rosin derivative (B) will be present in the emulsion.
The required amount of the rosin derivative (B ′) may be added all at once or sequentially, or may be added in the form of powder if the rosin derivative (B ′) is solid at room temperature. Alternatively, the rosin derivative (B ′) may be dissolved in an alkaline aqueous solution to form the rosin derivative (B) in advance, and the rosin derivative (B ′) may be added to the produced emulsion or polymerization container. The temperature at which the rosin derivative is added is preferably in the range of 0 to 90 ° C. Examples of the alkali that can be used include alkali metal compounds such as sodium hydroxide, alkaline earth metal compounds, alkylamines such as methylamine, and ammonia. When highly volatile alkylamines or ammonia are used, Since it does not remain in the film after drying, the water resistance is improved.

The timing of adding the compound (C) to the emulsion is not particularly limited, but the chemical reaction between the compound (C) and the rosin derivative (B) occurs during emulsion polymerization or during storage of the pressure-sensitive adhesive emulsion. To prevent the compound (C)
Is preferably mixed after the emulsion polymerization is completed and before the pressure-sensitive adhesive emulsion is applied. Compound (C) is
It may be added to the emulsion as it is or in the form of an aqueous dispersion with an emulsifier.

The pressure-sensitive adhesive polymer (A) is obtained in advance by a polymerization method other than emulsion polymerization instead of the above-mentioned production method, and water and an emulsifier are added and mechanically stirred to prepare an emulsion. A method of adding the rosin derivative (B ′) and the compound (C) to this emulsion can also be adopted. The pressure-sensitive adhesive polymer (A) and the rosin derivative (B ′) may be heated and melted and mixed, and then emulsified with an emulsifier. The rosin derivative (B ′) may be added to the emulsion after the polymer (A) is emulsified or after the emulsion is made alkaline. As described above, the compound (C) is preferably mixed after emulsifying the polymer (A) and before applying the emulsion for pressure-sensitive adhesive.
As a method for polymerizing the pressure-sensitive adhesive polymer (A) in this method, a solution polymerization method, a bulk polymerization method or the like may be adopted. Further, the polymer may be separated from water and used after it is prepared by emulsion polymerization or suspension polymerization.

The emulsion for pressure-sensitive adhesive of the present invention includes
Known crosslinking agents, wetting agents, viscosity modifiers, thickeners, defoamers,
Additives such as modifiers, pigments, colorants, fillers, antiaging agents, ultraviolet absorbers, and ultraviolet stabilizers may be added within the range not impairing the object of the present invention.

The emulsion for pressure-sensitive adhesives of the present invention is used for producing pressure-sensitive adhesive products. For example, a pressure-sensitive adhesive layer is formed on one surface of a support by coating the composition on a base material such as plastic film, paper, non-woven fabric, foam or release paper and forming a dry film thereof. It is possible to obtain products of the type having a pressure-sensitive adhesive layer formed on both sides of the support, the type having only a pressure-sensitive adhesive layer having no support, and the like. Further, it can be used not only in the field of pressure-sensitive adhesives but also in adhesives, paints, paper processing agents, fiber processing agents, mortar modifiers, sealing agents and the like.

[0066]

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%" and "part" means "part by mass".

Example 1 [Emulsion Polymerization of Pressure-Sensitive Adhesive Polymer] 100 parts of a monomer component having the composition shown in Table 1 and tert-dodecyl mercaptan (hereinafter abbreviated as TDM) as a molecular weight modifier 0.05
Parts, 1.5 parts of "HITENOL N-08" (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd .; polyoxyethylene alkylphenyl ether sulfonate) as an emulsifier, and azobis cyanovaleric acid (hereinafter abbreviated as ACVA) as a polymerization initiator. 0.05 parts and 35 parts of deionized water were mixed and stirred to prepare a monomer pre-emulsion.

Then, in a flask equipped with a dropping funnel, a stirrer, a thermometer, a nitrogen gas introducing tube and a reflux condenser, 2% of 100% of the monomer pre-emulsion was added,
33 parts of deionized water and 0.1 part of ACVA as an initiator were charged and reacted at about 80 ° C. for 10 minutes under a nitrogen atmosphere. Then, the remaining 98% of 100% of the monomer pre-emulsion was continuously added dropwise over about 3 hours to carry out a polymerization reaction. After the dropping was completed, the temperature was maintained at 80 ° C. for about 3 hours. A pressure sensitive adhesive polymer emulsion (A-1) was obtained.

Tg (° C.) of the obtained pressure-sensitive adhesive polymer
And the weight average molecular weight (Mw) are shown in Table 1. In addition, this Tg (° C.) is the T of the homopolymer of each monomer described later.
It is a value calculated by the above-mentioned mathematical expression using g (K), and Mw is a polystyrene conversion value measured using GPC.

[Composition of Rosin Derivative into Pressure-Sensitive Adhesive Polymer Emulsion] 2.2 parts of 25% aqueous ammonia was added to the flask containing the emulsion (A-1),
A rosin derivative (B ′) having an acid value of 235 and a softening point of 127 ° C. while maintaining at 80 ° C. (acid-modified rosin; “KE-60
4 ”; manufactured by Arakawa Chemical Co., Ltd .; Mn = 400, Mw = 410) 1
What was crushed appropriately in 0 part was put into the flask. An appropriate amount of water was added so that the calculated solid content was about 55%. When stirring was continued for about 1 hour, an emulsion (AB-1) in which the rosin derivative (B) was dissolved
was gotten. The solid content (%), average particle size (nm) and pH of the rosin derivative (B) -containing emulsion (AB-1) were measured and the results are shown in Table 1.

[Blending of Compound (C)] To 100 parts of this emulsion (AB-1), "Primal ASE-60" was added as a thickening agent to give a viscosity of 10,000 ± 8000 m.
It was adjusted to Pa · s (25 ° C .; B-type viscometer). afterwards,
As the compound (C), 1.0 part of "Chemite PZ-33" (manufactured by Nippon Shokubai Co .; compound containing 3 aziridinyl groups in one molecule; molecular weight 425 according to catalog) was used (of the above "KE-604"). (Equivalent to 0.34 equivalent to 1 equivalent of a carboxyl group) and mixed well to obtain Emulsion 1 for pressure-sensitive adhesive of the present invention.

[Preparation and Evaluation of Evaluation Tape] The emulsion 1 for pressure-sensitive adhesive was treated with a release paper (“K-80H”).
S "; manufactured by San-A Kaken Co., Ltd.), and the film thickness after drying is 25 μm
And was dried with a hot air dryer at 105 ° C. for 2 minutes. This was transferred to a polyethylene terephthalate film having a thickness of 50 μm to prepare a single-sided tape.
It was aged for 1 week or more in an atmosphere of ° C and a humidity of 65%. Then, the adhesive property was measured.

Example 2 The monomer component and the amount of TDM were changed as shown in Table 1, and the emulsifier was replaced by an ethylenically unsaturated double bond-containing reactive emulsifier ("Aqualon HS-10"; manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). Polymerization was carried out in the same manner as in Example 1 except that 2.0 parts of sulfuric acid ester ammonium salt of polyoxyethylene nonylpropenyl phenyl ether) was used to produce a pressure-sensitive adhesive polymer emulsion (A-2). Table 1 shows Tg and Mw of this polymer.

Then, in the same manner as in Example 1, 25
% 3.4% aqueous ammonia and the rosin derivative (B ')
15 parts of "KE-604" and an appropriate amount of water were added to the emulsion (A-2) and stirred to obtain a rosin derivative (B) -containing emulsion (AB-2). The results of measuring the solid content (%), average particle size (nm) and pH of this emulsion (AB-2) are shown in Table 1.

The viscosity of 100 parts of this emulsion (AB-2) was adjusted with a thickener in the same manner as in the example, and then, as the compound (C), "TETRAD-C" (manufactured by Mitsubishi Gas Chemical Co .; 1 Compound with 4 glycidyl groups in the molecule Epoxy equivalent 92, molecular weight 3 according to the catalog
66 parts) was added in an amount of 0.5 part (corresponding to 0.15 equivalent to 1 equivalent of the carboxyl group of "KE-604"), and the mixture was stirred well to obtain emulsion 2 for pressure-sensitive adhesive of the present invention. . In the same manner as in Example 1, a tape for evaluation was prepared using the above emulsion 2 and the adhesive property was evaluated.

Example 3 First, in order to synthesize an emulsifier for polymerization of the pressure-sensitive adhesive polymer (A-3), a flask equipped with a stirrer, a reflux condenser, a nitrogen introducing tube, a thermometer and a dropping funnel was charged with isopropyl. Charge 180 parts of alcohol and blow it with nitrogen at 81 ℃.
Increase the internal temperature to 10 isopropyl alcohol.
Reflux for minutes. Next, prepared acrylic acid 1
A monomer mixture consisting of 44 parts, 28.3 parts of n-dodecyl mercaptan, 33.6 parts of a lauryl acrylate-tridecyl acrylate mixture and 0.22 part of a polymerization initiator azobisisobutyronitrile was added dropwise over 2 hours to conduct polymerization. Let A solution with a solids content of 53.4% was obtained. Isopropyl alcohol was removed from this solution under reduced pressure to obtain a carboxyl group-containing oligomer-type emulsifier. The acid value of this synthetic emulsifier is 54
4, Mw was 2840.

Polymerization was carried out in the same manner as in Example 1 except that the monomer components and the amount of TDM were changed as shown in Table 1 and 1.5 parts of the above synthetic emulsifier was used as an emulsifier. An emulsion (A-3) was produced.
The oligomer emulsifier is 1.
To 5 parts, 1.0 part of 25% aqueous ammonia was added for neutralization before use. Table 1 shows Tg and Mw of the obtained polymer.

Then, in the same manner as in Example 1, 25
% Aqueous ammonia solution, acid value 245, softening point 131
Rosin derivative (B ') ("KE-604B"; Arakawa Chemical Co .; Mn = 410, Mw = 420) and an appropriate amount of water are added and stirred to obtain a rosin derivative (B) -containing emulsion (AB-3). ) Got. This emulsion (AB-
Table 1 shows the results of measuring the solid content (%), average particle size (nm) and pH of 3).

With respect to 100 parts of this emulsion (AB-3), the viscosity was adjusted with a thickener in the same manner as in Example 1, and then 1.5 parts of "TETRAD-C"(" KE-604B ”corresponding to 0.76 equivalent to 1 equivalent of a carboxyl group), and mixed well,
Emulsion 3 for pressure sensitive adhesive of the present invention was obtained. Example 1
In the same manner as above, an evaluation tape was prepared using the above emulsion 3 and the adhesive property was evaluated.

Example 4 100 parts of the rosin derivative (B) -containing emulsion (AB-1) obtained in Example 1 was added in the same manner as in Example 1
After adjusting the viscosity with a thickener, as compound (C),
3.0 parts of "TETRAD-C" (corresponding to 1.52 equivalents to 1 equivalent of carboxyl group of "KE-604") was mixed and stirred well to prepare the emulsion 4 for pressure-sensitive adhesive of the present invention. Obtained. In the same manner as in Example 1, an evaluation tape was prepared using the above emulsion 4, and the adhesive property was evaluated.

Comparative Example 1 The amounts of the monomer component and TDM were changed as shown in Table 1, the amount of the emulsifier "Hitenol N-08" was changed to 2.0 parts, and potassium persulfate was used instead of ACVA as the initiator. Was polymerized in the same manner as in Example 1 except that 0.1 part was used as a monomer pre-emulsion and 0.1 part was added as a charge at the time of dropping to obtain a pressure-sensitive adhesive polymer emulsion (A-4). Manufactured. Table 1 shows Tg and Mw of this polymer. Then, the solid content, particle size and pH were measured without adding the rosin derivative (B ′) to the emulsion (A-4), and the results are shown in Table 1. This emulsion (A
In the same manner as in Example 4, after adjusting the viscosity with a thickener, the evaluation tape was directly prepared and evaluated without adding the compound (C).

Comparative Example 2 For the emulsion (AB-3) obtained in Example 3,
After adjusting the viscosity with a thickener as in the example, the evaluation tape was prepared and evaluated without adding the compound (C).

The above results are summarized in Tables 1 and 2. In Table 1, each monomer name is abbreviated as follows. The numbers on the left are the Tg (K) values of homopolymers listed in the Polymer Handbook. 2EHA: 2-ethylhexyl acrylate 223K HEMA: 2-hydroxyethyl methacrylate 328K MMA: methyl methacrylate 378K BA: n-butyl acrylate 219K EA: ethyl acrylate 249K MAA: methacrylic acid 501K

[0084]

[Table 1]

[0085]

[Table 2]

[Evaluation Method of Adhesive Properties] The above Examples 1 to 1
The adhesive properties were evaluated by the following methods using the evaluation tapes obtained in Example 4 and Comparative Examples 1 and 2, and the results are shown in Table 3.

1. Holding power (against SUS plate) It was measured according to JIS Z 0237. A 25 mm wide and 150 mm long evaluation tape made of stainless steel (SUS)
The test piece is attached to a plate with an attachment area of 25 mm × 25 mm, and the non-attached portion of the tape is folded inside and used as a test piece. The test piece was suspended vertically in a constant temperature bath at 40 ° C., then a load of 1 kg was suspended on the folded portion of the tape and left for 24 hours. Deviation distance after 24 hours (m
m) was measured. Those that did not fall were judged to be ◯.

Adhesive strength (against SUS plate): JIS Z 02
According to 37, resistance when peeling a 25 mm width evaluation tape attached to a stainless steel plate at 180 ° (23 ° C)
Was measured. A value of 353 N / m (900 g / 25 mm) or more was evaluated as O, and a value of less than 353 N / m (900 g / 25 mm) was evaluated as Δ.

Adhesion (against PE plate): JIS Z 023
According to No. 7, the resistance when peeling the 25 mm wide evaluation tape attached to a polyethylene plate at 180 ° (23 ° C)
Was measured. A value of 137 N / m (350 g / 25 mm) or more was evaluated as O, and a value of less than 137 N / m (350 g / 25 mm) was evaluated as Δ.

Water absorption rate: The mass of an evaluation tape piece cut into 25 mm × 70 mm is measured. Let this be Wa. After this evaluation tape piece was immersed in 50 cc of water at 23 ° C. for 24 hours, it was taken out of the water, excess water on the surface was lightly wiped off, and the mass was measured again. This is Wb. The mass of only the PET film substrate of 25 mm × 70 mm is separately measured and set as Wc. Using each mass, the water absorption rate was calculated by the following formula. Water absorption rate (%) = (Wb−Wa) / (Wa−Wc) × 10
0 Water absorption rate is less than 10% ◎, 10% or more 2
Less than 5% was evaluated as ◯, 25% or more and less than 50% was evaluated as Δ, and 50% or more was evaluated as x.

Water whitening resistance: A pressure-sensitive adhesive tape piece cut into 25 mm × 70 mm was immersed in 50 cc of water at 23 ° C. for 24 hours, and the whitening degree of the pressure-sensitive adhesive was visually evaluated. For the judgment, those having a transparent feeling were marked with ⊚, those that were slightly whitened were marked with ◯, and those that had become cloudy were marked with x.

Coatability: Release paper ("K-80HS" manufactured by San-A Kaken Kogyo Co., Ltd.) that has been subjected to a silicone-based release treatment.
The coating property when the emulsion was wet coated to have a thickness of 75 μm was visually evaluated. Judgment is ◎, repellency, shrinkage, that a clean coating film can be obtained without occurrence of cissing, shrinkage, streaks, pinholes, etc.
A film with almost no streaks or pinholes and a practically non-problematic coating film was evaluated as ◯, and any repelling, shrinkage, streaks, or pinholes were evaluated as x. .

[0093]

[Table 3]

[0094]

INDUSTRIAL APPLICABILITY Since the present invention is an emulsion obtained by combining a rosin derivative and a compound having a functional group capable of reacting with the carboxyl group of this rosin derivative with a pressure-sensitive adhesive polymer, good water resistance after film formation is obtained. Indicates. Further, since it has excellent adhesive properties such as adhesive strength, adhesiveness to olefin, and cohesive strength, it was possible to provide a high-performance pressure-sensitive adhesive product.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C09J 193/04 C09J 193/04 // C09J 9/00 9/00 (56) Reference JP-A-61-215674 (JP, A) ) JP-A-6-322347 (JP, A) JP-A-9-3107 (JP, A) JP-A-7-26232 (JP, A) JP-A-10-204401 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C09J 201/00-201/10 C09J 11/06-11/08 C09J 133/08 C09J 157/00-157/12 C09J 193/04 C09J 9/00-9 / 02

Claims (4)

(57) [Claims] 1. A pressure-sensitive adhesive polymer (A) having a glass transition temperature of −80 to −20 ° C., a weight average molecular weight of 150,000 or more and an acid value of a carboxyl group of 30 or less, and a weight average molecular weight of 100,000 or less. A carboxyl group-containing rosin derivative (B) in which the acid value of the carboxyl group before alkalization is 190 or more, and a part or all of the carboxyl group is an alkali salt; and a weight average molecular weight of 100,000 or less. A compound (C) having no carboxyl group and having at least one functional group reactive with a carboxyl group in one molecule,
An emulsion containing as an essential component, wherein the rosin derivative (B) is 2 when the total amount of the pressure-sensitive adhesive polymer (A) and the rosin derivative (B) contained in the emulsion is 100% by mass. ~ 30 mass%
The compound (C) is contained so that the functional group of the compound (C) is 0.05 to 10 equivalents relative to 1 equivalent of the carboxyl group of the rosin derivative (B). An emulsion for pressure-sensitive adhesives characterized by the following. 2. The pressure-sensitive adhesive polymer (A) as described above.
The emulsion for pressure-sensitive adhesives according to claim 1, which contains an emulsifier having no reactivity with the monomer for use in the pressure-sensitive adhesive. 3. The emulsion for pressure-sensitive adhesives according to claim 1, wherein the compound (C) is an aziridinyl group-containing compound and / or polyglycidyl amine. 4. The pressure-sensitive adhesive polymer is prepared by emulsion polymerization using an emulsifier having no reactivity with the monomer for the pressure-sensitive adhesive polymer (A) and / or an emulsifier having an ethylenically unsaturated double bond. After obtaining the emulsion of (A), an alkaline aqueous solution is added to the obtained emulsion to give an alkaline emulsion. In this alkaline emulsion, the weight average molecular weight is 100,000 or less, and the acid value of the carboxyl group is 190 or more. The emulsion for pressure-sensitive adhesives according to any one of claims 1 to 3, which is obtained by adding a carboxyl group-containing rosin derivative (B ') and further adding the compound (C).