JP7390874B2 - adhesive - Google Patents

Description

The present invention relates to adhesives. More specifically, the present invention relates to an adhesive that can be suitably used for surface protection adhesive sheets such as displays and touch panels of electronic devices such as mobile phones, smartphones, and computers, and an adhesive comprising the adhesive. The present invention relates to a pressure-sensitive adhesive sheet in which a layer is formed on at least one surface of a base material.

Adhesives containing acrylic adhesive polymers and plasticizers can be used, for example, as protective films for glass plates, metal plates, resin plates, etc., masking tapes used during painting, curing tapes, adhesive tapes for temporarily holding construction materials, etc. It is used in the adhesive layer of adhesive products.

When the adhesive strength of the adhesive layer is high, when an adhesive tape having the adhesive layer is attached to an adherend, it is difficult to reapply the adhesive tape, and when the adhesive tape is peeled off after being attached, the adhesive becomes sticky. Since part of the layer may transfer to the surface of the adherend, the adhesive strength of the adhesive layer to the adherend at 25°C is set to be approximately 15 to 100 g/25 mm, and recently In order to peel off the adhesive tape quickly, the adhesive force is controlled to be even lower (15 g/25 mm or less). As a pressure-sensitive adhesive that exhibits low adhesive strength, an acrylic resin adhesive with a glass transition point of -40°C or lower, an adhesive containing a plasticizer, and a crosslinking agent has been proposed (for example, Patent Document 1 reference).

However, when the acid value of the acrylic resin adhesive used in the adhesive is high, the storage stability of the adhesive is not only poor, but also the adhesive tape having the adhesive layer made of the adhesive has a high acid value. When the adhesive layer is attached to an adherend and then peeled off from the adherend after a long period of time, a portion of the adhesive layer may be transferred to the surface of the adherend. Therefore, it is conceivable to lower the acid value of the adhesive, but when the acid value of the adhesive is lowered, there is a technical problem that the adhesive force cannot be suppressed low.

In order to solve the above technical problem, an adhesive composition exhibiting low adhesive strength contains an acrylic adhesive polymer and a plasticizer, the acid value of the acrylic adhesive polymer is 15 mgKOH/g or less, and the adhesive composition exhibits low adhesive strength. A pressure-sensitive adhesive composition using an adipic acid diester as a plasticizer has been proposed (see, for example, Patent Document 2).

However, in recent years, large amounts of plasticizers have been used to improve the adhesive film's low tackiness, excellent air release properties when attached to adherends, and mechanical strength of the formed adhesive layer. However, it is desired to develop an adhesive in which the plasticizer forms an adhesive layer that is difficult to bleed out.

Japanese Patent Application Publication No. 05-247416 Japanese Patent Application Publication No. 2005-247903

The present invention has been made in view of the above-mentioned prior art, and has low tackiness, excellent air release properties when adhering an adhesive film to an adherend, and excellent mechanical strength of the formed adhesive layer. , an adhesive that forms an adhesive layer that does not allow the plasticizer to bleed out even though a large amount of the plasticizer is used, and an adhesive layer made of the adhesive that is formed on at least one surface of the base material. The objective is to provide a pressure-sensitive adhesive sheet that

The present invention
(1) An adhesive containing a carboxyl group-containing (meth)acrylic polymer, a metal chelate crosslinking agent, and a plasticizer, wherein the carboxyl group-containing (meth)acrylic polymer has an acid value of 10 mgKOH/g or more. , the amount of the metal chelate crosslinking agent relative to the carboxyl group of the carboxyl group-containing (meth)acrylic polymer is 0.1 equivalent or more, and the amount of plasticizer per 100 parts by mass of the carboxyl group-containing (meth)acrylic polymer An adhesive characterized in that the amount is 10 to 200 parts by mass,
(2) The adhesive according to (1) above, wherein the plasticizer is an aliphatic carboxylic acid ester plasticizer;
(3) The pressure-sensitive adhesive according to (1) or (2) above, further containing at least one crosslinking agent selected from the group consisting of isocyanate crosslinking agents and epoxy crosslinking agents;
(4) A pressure-sensitive adhesive sheet comprising an adhesive layer formed of the pressure-sensitive adhesive according to any one of (1) to (3) above on at least one surface of a base material;
(5) An adhesive layer made of the adhesive according to any one of (1) to (3) above is formed on one surface of the base material, and the other surface of the base material has an adhesive force different from that of the adhesive layer. and (6) the double-sided adhesive sheet according to (4) or (5) above, wherein the base material is formed of a (meth)acrylic polymer having a crosslinked structure. .

According to the present invention, the adhesive film has low adhesion, has excellent air release properties when adhering the adhesive film to an adherend, and has excellent mechanical strength of the formed adhesive layer, and uses a large amount of plasticizer. Nevertheless, there are provided an adhesive in which the plasticizer forms an adhesive layer from which it is difficult to seep out, and an adhesive sheet in which an adhesive layer made of the adhesive is formed on at least one surface of a base material.

FIG. 2 is a schematic explanatory diagram of an evaluation method for evaluating air release properties in each Example and each Comparative Example.

As described above, the adhesive of the present invention is an adhesive containing a carboxyl group-containing (meth)acrylic polymer, a metal chelate crosslinking agent, and a plasticizer, and the adhesive of the carboxyl group-containing (meth)acrylic polymer the amount of plasticizer is 10 to 200 parts by mass per 100 parts by mass of the carboxyl group-containing (meth)acrylic polymer, and the carboxyl group-containing (meth)acrylic polymer has a It is characterized in that the amount of metal chelate crosslinking agent relative to the group is 0.1 equivalent or more. Since the adhesive of the present invention has the above-mentioned constituent requirements, it has low tackiness, excellent air release properties when an adhesive film is attached to an adherend, and excellent mechanical strength of the formed adhesive layer. , the amount of plasticizer per 100 parts by mass of acrylic polymer is 10 to 200 parts by mass, so even though a large amount of plasticizer is used, the plasticizer has the property of being difficult to exude (hereinafter referred to as leaching). It exhibits the excellent effect of being able to form an adhesive layer that has a property called "deterrent property".

In the present invention, "(meth)acrylate" means "acrylate" or "methacrylate", and acrylate and methacrylate may be used alone or in combination. "(Meth)acrylic acid" means "acrylic acid" or "methacrylic acid", and acrylic acid and methacrylic acid may be used alone or in combination. "(Meth)acrylic" means "acrylic" or "methacrylic".

Moreover, in the present invention, low tackiness means that the tackiness at 25° C. is 100 g/25 mm or less as measured based on the method described in the following examples.

The acid value of the carboxyl group-containing (meth)acrylic polymer has low tackiness, excellent air release properties and mechanical strength when the adhesive film is attached to an adherend, and an adhesive layer that has oozing prevention properties. From the viewpoint of obtaining a pressure-sensitive adhesive that forms a From the viewpoint of suppressing the transfer of a part of the adhesive layer to the surface of the adherend when the tape is peeled off after being applied, and also suppressing corrosion of metal, preferably 70 mgKOH/g or less, more preferably 60 mgKOH/g. g or less, more preferably 55 mgKOH/g or less, even more preferably 50 mgKOH/g or less.

The carboxyl group-containing (meth)acrylic polymer is not particularly limited as long as it has the above-mentioned acid value, but it has low adhesiveness and has good air release properties and mechanical properties when attaching an adhesive film to an adherend. From the viewpoint of obtaining an adhesive that forms an adhesive layer with excellent strength and oozing prevention properties, a carboxyl group-containing (meth) which is obtained by polymerizing a monomer component whose main components are a carboxyl group-containing monomer and a (meth)acrylate monomer. Acrylic polymers are preferred.

Examples of carboxyl group-containing monomers include (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and crotonic acid, but the present invention is not limited to these examples. . These carboxyl group-containing monomers may be used alone or in combination of two or more. Among these carboxyl group-containing monomers, adhesives that have low tackiness, have excellent air release properties and mechanical strength when adhering an adhesive film to an adherend, and form an adhesive layer that has oozing prevention properties are preferred. From the viewpoint of obtaining the agent, (meth)acrylic acid is preferred.

The content of the carboxyl group-containing monomer in the monomer component is the amount required for the carboxyl group-containing (meth)acrylic polymer to have the above acid value. The content of the carboxyl group-containing monomer in the monomer component forms an adhesive layer that has low adhesiveness, has excellent air release properties and mechanical strength when the adhesive film is attached to an adherend, and has oozing prevention properties. From the viewpoint of obtaining a pressure-sensitive adhesive, the amount is preferably 1 to 10% by mass, more preferably 1.5 to 9% by mass, and even more preferably 2 to 8% by mass.

Examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and tert-butyl (meth)acrylate. , cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, dodecyl Alkyl (meth)acrylates such as (meth)acrylate, amyl (meth)acrylate, and octadecyl (meth)acrylate; (meth)acrylates containing aromatic rings such as benzyl (meth)acrylate; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate; ) acrylate, hydroxyl group-containing (meth)acrylates such as hydroxyalkyl (meth)acrylates having 2 to 4 carbon atoms in the ester moiety, such as hydroxybutyl (meth)acrylate, and caprolactone-modified hydroxy(meth)acrylates; isobornyl (meth)acrylates However, the present invention is not limited to only such examples. These (meth)acrylate monomers may be used alone or in combination of two or more. Among the (meth)acrylate monomers, alkyl (meth)acrylates and hydroxyl group-containing (meth)acrylates are preferred.

Among the alkyl (meth)acrylates, alkyl (meth)acrylates in which the alkyl group has 1 to 12 carbon atoms are preferred, alkyl (meth)acrylates in which the alkyl group has 4 to 12 carbon atoms are more preferred; Alkyl (meth)acrylates having 4 to 8 carbon atoms are more preferred, and n-butyl acrylate and 2-ethylhexyl acrylate are even more preferred.

The lower limit of the content of alkyl (meth)acrylate in the monomer component has low tackiness, excellent air release properties and mechanical strength when adhering the adhesive film to an adherend, and oozing prevention properties. From the viewpoint of obtaining an adhesive that forms an adhesive layer, the content is preferably 60% by mass or more, more preferably 65% by mass or more, and even more preferably 70% by mass or more. The upper limit of the content of (meth)acrylate monomers in the monomer components is determined by the following: low tackiness, excellent air release properties and mechanical strength when the adhesive film is attached to an adherend, and oozing prevention properties. From the viewpoint of obtaining a pressure-sensitive adhesive that forms a pressure-sensitive adhesive layer, the content is preferably 99% by mass or less, more preferably 98.5% by mass or less, even more preferably 98% by mass or less.

Among the hydroxyl group-containing (meth)acrylates, hydroxyalkyl (meth)acrylates in which the ester moiety has 2 to 4 carbon atoms are preferred, hydroxyethyl (meth)acrylate and hydroxybutyl (meth)acrylate are more preferred, and hydroxyethyl (meth)acrylates are more preferred. Meth)acrylate is more preferred, and hydroxyethyl acrylate is even more preferred. The content of the hydroxyl group-containing monomer in the monomer component forms an adhesive layer that has low adhesiveness, has excellent air release properties and mechanical strength when the adhesive film is attached to an adherend, and has oozing prevention properties. From the viewpoint of obtaining an adhesive, it is preferably 0 to 5% by mass, more preferably 0.1 to 5% by mass, even more preferably 0.1 to 3% by mass, even more preferably 0.3 to 3% by mass. .

The monomer component may contain monomers other than carboxyl group-containing monomers and (meth)acrylate monomers (hereinafter referred to as other monomers) within a range that does not impede the object of the present invention. The amount of other monomers is preferably a balanced amount so that the total amount of monomer components is 100% by mass.

Other monomers include, for example, aliphatic unsaturated hydrocarbon compounds such as ethylene, butadiene, and isoprene; halogen-substituted aliphatic unsaturated hydrocarbon compounds such as vinyl chloride; styrene, α-methylstyrene, vinyltoluene, etc. Aromatic unsaturated hydrocarbon compounds; vinyl esters such as vinyl acetate and vinyl propionate; N-vinylpyrrolidone, (meth)acrylonitrile, (meth)acrylamide, N-isopropylacrylamide, N-butoxymethylacrylamide, N-phenylmaleimide, Examples include nitrogen atom-containing unsaturated monomers such as N-cyclohexylmaleimide, N-vinylimidazole, N-vinylpyridine, N,N-dimethylacrylamide, and isopropenyloxazoline, but the present invention is limited only to such examples. It's not a thing. These monomers may be used alone or in combination of two or more. Among these other monomers, vinyl acetate is preferred.

Note that the monomer component may contain a chain transfer agent in order to adjust the molecular weight of the carboxyl group-containing (meth)acrylic polymer. Examples of chain transfer agents include 2-mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionate, and 2-mercaptopropionic acid. Thiol compounds such as ethanesulfonic acid, n-dodecyl mercaptan, octyl mercaptan, and butyl thioglycolate; halides such as carbon tetrachloride, methylene chloride, bromoform, and bromotrichloroethane; secondary alcohols such as isopropanol; phosphorous acid and its salts, hypophosphorous acid and its salts, sulfurous acid and its salts, hydrogen sulfite and its salts, dithionite and its salts, metabisulfite and its salts, etc., but the present invention is limited only to such examples. It is not something that will be done. The amount of chain transfer agent varies depending on the molecular weight of the target carboxyl group-containing (meth)acrylic polymer and cannot be determined unconditionally. It is preferable to adjust it accordingly.

When polymerizing the monomer components, it is preferable to include a polymerization initiator in the monomer components from the viewpoint of allowing the polymerization of the monomer components to proceed smoothly.

Examples of the polymerization initiator include azo polymerization initiators, peroxide polymerization initiators, and the like, and each of these may be used alone or two or more types may be used in combination. Examples of the azo polymerization initiator include azoisobutyronitrile, 2,2'-azobisisobutyronitrile, 2,2'-azobis-(2-methylbutyronitrile), 2,2'-azo Examples include biscyclohexanecarbonitrile, but the present invention is not limited to such examples. These azo polymerization initiators may be used alone or in combination of two or more. Examples of peroxide-based polymerization initiators include tert-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, and tert-butyl peroxybenzoate. However, the present invention is not limited to such examples. These peroxide-based polymerization initiators may be used alone, or two or more types may be used in combination.

The amount of the polymerization initiator is not particularly limited, but is usually preferably 0.001 to 2 parts by weight, more preferably 0.01 to 1 part by weight, per 100 parts by weight of the monomer components.

Examples of methods for polymerizing monomer components include solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization, but the present invention is not limited to these examples. Among these polymerization methods, the solution polymerization method is preferred because it allows easy control of the molecular weight and composition of the resulting carboxyl group-containing (meth)acrylic polymer.

A solvent is used when monomer components are polymerized by solution polymerization. Examples of solvents include aliphatic hydrocarbon compounds such as n-hexane and n-heptane; alicyclic hydrocarbon compounds such as cyclohexane; aromatic compounds such as benzene, toluene, and xylene; and isopropyl alcohol and n-butyl alcohol. Alcohol; Ethers such as propylene glycol methyl ether, dipropylene glycol methyl ether, ethyl cellosolve, butyl cellosolve; Esters such as ethyl acetate, butyl acetate, cellosolve acetate; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetone alcohol; dimethyl formamide Examples include organic solvents such as amides such as, but the present invention is not limited to such examples. These solvents may be used alone or in combination of two or more. Among these solvents, toluene and ethyl acetate are preferred.

The amount of the solvent may be appropriately determined depending on the polymerization conditions, the type of monomer used as the monomer component, the composition thereof, and the like.

The polymerization of the monomer components is preferably carried out in an inert gas atmosphere such as argon gas or nitrogen gas. From the viewpoint of increasing the polymerization rate and production efficiency, the polymerization temperature of the monomer component is usually about 30 to 100°C, preferably 40 to 90°C, more preferably 50 to 85°C. The polymerization time cannot be determined unconditionally because it varies depending on the polymerization temperature, the type and amount of raw material monomers, etc., so it is preferable to adjust it appropriately according to these factors, but it is usually about 0.5 to 10 hours. It is.

By polymerizing the monomer components as described above, a carboxyl group-containing (meth)acrylic polymer can be prepared. The weight average molecular weight of the carboxyl group-containing (meth)acrylic polymer is preferably 200,000 or more, more preferably 200,000 or more, from the viewpoint of obtaining an adhesive that forms an adhesive layer that has excellent mechanical strength and ooze-preventing properties. 300,000 or more, more preferably 400,000 or more, from the viewpoint of obtaining an adhesive that has low tackiness and forms an adhesive layer with excellent air release properties when adhering an adhesive film to an adherend. Preferably it is 1,500,000 or less, more preferably 1,000,000 or less, still more preferably 800,000 or less, even more preferably 750,000 or less.

In the present invention, the weight average molecular weight of the carboxyl group-containing (meth)acrylic polymer is measured using a gel permeation chromatography (GPC) measuring device manufactured by Tosoh Corporation, product number: HLC-8220GPC, separation column: Means the converted value based on standard polystyrene (manufactured by Tosoh Corporation) using product number: TSKgel Super HZM-M manufactured by Tosoh Corporation.

The glass transition temperature of the carboxyl group-containing (meth)acrylic polymer is preferably -80°C or higher, more preferably -80°C or higher, from the viewpoint of obtaining an adhesive that forms an adhesive layer that has excellent mechanical strength and ooze-preventing properties. to obtain an adhesive that has a temperature of -70°C or higher, more preferably -65°C or higher, has low tackiness, and forms an adhesive layer with excellent air release properties when the adhesive film is attached to an adherend. From this point of view, the temperature is preferably -20°C or lower, more preferably -25°C or lower, and still more preferably -30°C or lower.

The glass transition temperature of the carboxyl group-containing (meth)acrylic polymer is determined by the formula:
1/Tg=Σ(Wm/Tgm)/100
[In the formula, Wm represents the content (% by weight) of monomer m in the monomer components constituting the polymer, and Tgm represents the glass transition temperature (absolute temperature: K) of the homopolymer of monomer m.]
It means the temperature determined based on the Fox equation expressed by

The glass transition temperature of a carboxyl group-containing (meth)acrylic polymer (non-volatile content) is the glass transition temperature of a homopolymer composed of monomers contained in the monomer component used as a raw material for the carboxyl group-containing (meth)acrylic polymer. From the temperature (Tg) (absolute temperature: K) and the mass fraction of the monomer, formula (I):
1/Tg=W1/Tg ₁ +W ₂ /Tg ₂ +W ₃ /Tg ₃ +...+W _n /Tg _n (I)
[In the formula, Tg is the glass transition temperature (K) of the carboxyl group-containing (meth)acrylic polymer to be determined, and W ₁ , W ₂ , W ₃ . . . W _n is the mass of each monomer, respectively. Tg ₁ , Tg ₂ , Tg ₃ . . . Tg _n indicate the glass transition temperature (K) of a homopolymer made of monomers corresponding to the mass fraction of each monomer.]
It can be determined based on the Fox equation expressed as follows.

In this specification, the glass transition temperature of the carboxyl group-containing (meth)acrylic polymer means the glass transition temperature determined based on formula (I). Note that for monomers whose glass transition temperatures are unknown, such as special monomers and polyfunctional monomers, the glass transition temperature can be determined using only monomers whose glass transition temperatures are known.

The glass transition temperature of a homopolymer is, for example, 106°C for a homopolymer of acrylic acid, 130°C for a homopolymer of methacrylic acid, -70°C for a homopolymer of 2-ethylhexyl acrylate, and -70°C for a homopolymer of n-butyl acrylate. -55°C for the polymer, 10°C for the homopolymer of methyl acrylate, 105°C for the homopolymer of methyl methacrylate, -24°C for the homopolymer of ethyl acrylate, and -54°C for the homopolymer of n-butyl acrylate. , -20°C for n-butyl methacrylate homopolymer, -80°C for n-octyl acrylate homopolymer, -58°C for isooctyl acrylate homopolymer, and 16°C for cyclohexyl acrylate homopolymer. , 83°C for a homopolymer of cyclohexyl methacrylate, 180°C for a homopolymer of isobornyl methacrylate, -15°C for a homopolymer of 2-hydroxyethyl acrylate, and 85°C for a homopolymer of 2-hydroxyethyl methacrylate. ℃, -32°C for a homopolymer of 4-hydroxybutyl acrylate, and 30°C for a homopolymer of vinyl acetate.

The glass transition temperature of the carboxyl group-containing (meth)acrylic polymer can be determined by appropriately adjusting the type and amount of the monomer used in the monomer component used when preparing the carboxyl group-containing (meth)acrylic polymer. Can be easily adjusted.

The adhesive of the present invention contains a metal chelate crosslinking agent. Examples of metal chelate crosslinking agents include coordination compounds of polyvalent metals and acetylacetone or ethyl acetoacetate. Examples of polyvalent metals include aluminum, iron, copper, zinc, tin, titanium, nickel, and zirconium, but the present invention is not limited to these examples. Among these polyvalent metals, adhesives have low adhesiveness, have excellent air release properties and mechanical strength when adhering an adhesive film to an adherend, and form an adhesive layer that has oozing prevention properties. From the viewpoint of obtaining, aluminum, titanium and zirconium are preferable, and aluminum is more preferable.

Specific examples of suitable metal chelate crosslinking agents include aluminum tris(ethylacetoacetate), aluminum alkyl acetoacetate diisopropylate, aluminum acetylacetate bis(ethylacetoacetate), titanium acetylacetonate, titanium tetraacetylacetonate, Examples include titanium ethyl acetoacetate, titanium-1,3-propanedioxybis(ethyl acetoacetate), zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium ethyl acetoacetate, etc., but the present invention is limited to such examples. It is not limited to. These metal chelate crosslinking agents may be used alone or in combination of two or more. Among these metal chelate crosslinking agents, it has low adhesiveness, has excellent air release properties and mechanical strength when adhering an adhesive film to an adherend, and forms an adhesive layer that has oozing prevention properties. From the viewpoint of obtaining an adhesive, aluminum tris(ethyl acetoacetate), aluminum alkyl acetoacetate diisopropylate and aluminum acetylacetate bis(ethyl acetoacetate) are preferred.

The adhesive of the present invention may contain at least one compound selected from the group consisting of acetylacetone, alcohol, acetoacetate, and malonic acid ester, if necessary, within a range that does not impede the object of the present invention. preferable. When the above compound is contained in the adhesive, the compound acts on the metal chelate crosslinking agent, lengthens the curing time and pot life of the adhesive, and improves the followability to the adherend.

Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n-pentanol, isopentanol, n-hexanol, 4-methyl-2-pentanol, 1-Heptanol, 1-octanol, isooctanol, 2-ethylhexanol, n-nonanol, isononanol, n-decanol, n-dodecanol, n-myristyl alcohol, cetyl alcohol, n-stearyl alcohol, isostearyl alcohol, 2-octyl Examples include decanol, 2-octyldodecanol, 2-hexyldecanol, behenyl alcohol, oleyl alcohol, but the present invention is not limited to these examples. Examples of the acetoacetate include methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, butyl acetoacetate, isobutyl acetoacetate, tert-butyl acetoacetate, etc., but the present invention is limited only to such examples. It's not something you can do. Examples of the malonic acid ester include dimethyl malonate, diethyl malonate, dibutyl malonate, but the present invention is not limited to these examples. Among these compounds, acetylacetone is preferred from the viewpoint of acting on the metal chelate crosslinking agent and prolonging the curing time of the adhesive.

The amount of metal chelate crosslinking agent relative to the carboxyl group of the carboxyl group-containing (meth)acrylic polymer is 0.1 equivalent from the viewpoint of obtaining an adhesive that has excellent mechanical strength and forms an adhesive layer that has exudation inhibiting properties. The amount is preferably 0.2 equivalent or more. In addition, the amount of the metal chelate crosslinking agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the plasticizer, from the viewpoint of preventing the metal chelate crosslinking agent from precipitating from the adhesive layer. The amount is preferably 10 parts by mass or less.

Note that the adhesive of the present invention may contain a crosslinking agent other than the metal chelate crosslinking agent in order to adjust the adhesive force of the adhesive layer within a range that does not impede the object of the present invention. Examples of crosslinking agents other than metal chelate crosslinking agents include isocyanate crosslinking agents and epoxy crosslinking agents, but the present invention is not limited to these examples. These crosslinking agents may be used alone or in combination. Among these crosslinking agents, isocyanate crosslinking agents are preferred from the viewpoint of improving the adhesiveness between the adhesive and the base material.

An isocyanate-based crosslinking agent is a crosslinking agent having two or more isocyanate groups in one molecule. Examples of the isocyanate group-containing crosslinking agent include aromatic polyisocyanates such as xylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated products of the above aromatic polyisocyanates. Examples include aliphatic or alicyclic polyisocyanates, dimers or trimers of these polyisocyanates, and adducts consisting of polyisocyanates such as trimethylolpropane triisocyanate and polyols such as trimethylolpropane. The invention is not limited to such examples only. These isocyanate-based crosslinking agents may be used alone or in combination of two or more. Examples of commercially easily available isocyanate group-containing crosslinking agents include Coronate L, Coronate L-55E, Coronate HX, Coronate HL, Coronate HL-S, Coronate 2234, Aquanate 200, Aquanate 210 [ The above products are manufactured by Nippon Polyurethane Industries Co., Ltd., "Coronate" and "Aquanate" are registered trademarks], Desmodur N3400 [Bayer A. G. manufactured by Asahi Kasei Chemicals Co., Ltd., "Desmodule" is a registered trademark), Duranate D-201, Duranate TSE-100, Duranate TSS-100, Duranate 24A-100, Duranate E-405-80T (manufactured by Asahi Kasei Chemicals Co., Ltd.), Duranate" is a registered trademark], Takenate D-110N, Takenate D-120N, Takenate M-631N, MTERT-Orestar NP1200 [all manufactured by Mitsui Chemicals Polyurethanes Co., Ltd., "Takenate" and "Orestar" are registered trademarks) However, the present invention is not limited to only such examples.

An epoxy crosslinking agent is a crosslinking agent having two or more epoxy groups in one molecule. Examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin, N,N,N',N'-tetraglycidyl- Examples include m-xylene diamine, 1,3-bis(N,N-diglycidyl aminomethyl)cyclohexane, N,N-diglycidylaniline, N,N-diglycidyltoluidine, etc., but the present invention is limited to such examples. It is not limited to. These epoxy crosslinking agents may be used alone or in combination of two or more. Examples of commercially easily available epoxy crosslinking agents include amino group-containing epoxy curing agents such as TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.

The amount of the crosslinking agent other than the metal chelate crosslinking agent per 100 parts by mass of the carboxyl group-containing (meth)acrylic polymer is determined from the viewpoints of improving cohesive force by forming a crosslinked structure and improving the adhesiveness of the pressure-sensitive adhesive. The amount is preferably 0.001 to 0.05 parts by mass, more preferably 0.005 to 0.01 parts by mass.

The adhesive of the present invention contains a plasticizer. Examples of plasticizers include aliphatic plasticizers and aromatic plasticizers. These plasticizers may be used alone or in combination. Among these plasticizers, we use adhesives that have low tackiness, have excellent air release properties and mechanical strength when adhering adhesive films to adherends, and form adhesive layers that have oozing prevention properties. From the viewpoint of yield, aliphatic plasticizers are preferred, aliphatic carboxylic acid plasticizers are more preferred, and aliphatic dicarboxylic acid ester plasticizers are even more preferred.

Examples of aliphatic dicarboxylic acid ester plasticizers include adipic acid diester, sebacic acid diester, and azelaic acid diester, but the present invention is not limited to these examples. These aliphatic dicarboxylic acid ester plasticizers may be used alone or in combination of two or more. Among these aliphatic dicarboxylic acid ester plasticizers, the adhesive layer has low adhesiveness, has excellent air release properties and mechanical strength when adhering the adhesive film to the adherend, and has oozing prevention properties. Adipic acid diester is preferred from the viewpoint of obtaining an adhesive that forms.

Examples of the diester adipate include dibutyl adipate, dioctyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, and bis(2-butoxyethyl) adipate, but the present invention is not limited to these examples. These adipic acid diesters may be used alone or in combination of two or more. Among these adipic acid diesters, there are adhesives that have low tackiness, have excellent air release properties and mechanical strength when adhering an adhesive film to an adherend, and form an adhesive layer that has oozing prevention properties. From the viewpoint of obtaining a dialkyl adipate having an alkyl group having 4 to 12 carbon atoms and an alkoxyalkyl adipate having an alkoxy group having 1 to 4 carbon atoms, the alkyl group in the main chain having 1 to 8 carbon atoms. Ester is preferred, adipic acid dialkyl ester having an alkyl group having 4 to 12 carbon atoms is more preferred, and adipic acid dialkyl ester having an alkyl group having 8 to 12 carbon atoms is even more preferred, and having an alkyl group having 9 to 12 carbon atoms. Even more preferred are dialkyl adipates, with diisodecyl adipate and diisononyl adipate being particularly preferred.

Examples of dialkyl sebacate include dibutyl sebacate, dioctyl sebacate, bis(2-ethylhexyl) sebacate, diisononyl sebacate, diisodecyl sebacate, bis(2-butoxyethyl) sebacate, etc. The invention is not limited to such examples only. These sebacic acid diesters may be used alone or in combination of two or more.

Examples of dialkyl azelate include dibutyl azelate, dioctyl azelate, bis(2-ethylhexyl) azelate, diisononyl azelate, diisodecyl azelate, and bis(2-butoxyethyl) azelate. The invention is not limited to such examples only. These azelaic acid diesters may be used alone, or two or more types may be used in combination.

The amount of plasticizer per 100 parts by mass of the carboxyl group-containing (meth)acrylic polymer has low tackiness, excellent air release properties and mechanical strength when adhering the adhesive film to an adherend, and no oozing. From the viewpoint of obtaining an adhesive that forms an adhesive layer having inhibiting properties, the amount is 10 parts by mass or more, preferably 15 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, and prevents oozing of the adhesive layer. From the viewpoint of improving deterrence, the amount is 200 parts by mass or less, preferably 180 parts by mass or less, and more preferably 150 parts by mass or less.

The pressure-sensitive adhesive of the present invention may contain polymers other than acrylic polymers, if necessary, within a range that does not impede the object of the present invention. In addition, the adhesive of the present invention may include fillers, cationic antistatic agents, anionic antistatic agents, amphoteric antistatic agents, nonionic antistatic agents, ionic conductive Additives such as antistatic agents, crosslinking accelerators, tackifiers, modifiers, pigments, fillers, anti-aging agents, ultraviolet absorbers, ultraviolet stabilizers, flame retardants, thixotropic agents, etc. May be included.

The adhesive of the present invention can be easily prepared by mixing a carboxyl group-containing (meth)acrylic polymer, a metal chelate crosslinking agent, a plasticizer, and, if necessary, a solvent, a crosslinking agent other than the metal chelate crosslinking agent, additives, etc. It can be prepared as follows.

The nonvolatile content in the adhesive of the present invention is preferably 20% by mass or more, more preferably 30% by mass or more from the viewpoint of improving productivity, and preferably 80% by mass from the viewpoint of improving coatability. The content is more preferably 70% by mass or less. The nonvolatile content in the adhesive can be adjusted by adjusting the amount of solvent contained in the adhesive. The solvent may be the same as the solvent used when polymerizing the monomer components.

The adhesive sheet of the present invention has an adhesive layer and a base material, and the adhesive layer made of the adhesive of the present invention is formed on at least one surface of the base material. Therefore, the adhesive layer may be formed only on one surface of the base material, or may be formed on both surfaces of the base material, or it may be formed on one surface of the base material and the adhesive layer on the other surface. An adhesive layer having adhesive force different from that of the adhesive layer may be formed.

Note that the term "adhesive sheet" as used in the present invention includes the concepts of sheet, film, and tape.

Examples of base materials include papers such as high-quality paper, kraft paper, crepe paper, and glassine paper; films made of resins such as acrylic resin, polyethylene, polypropylene, polyester, polystyrene, polyvinyl chloride, and cellophane; woven fabrics; and non-woven fabrics. , fiber products such as fabrics, and base materials used in double-sided adhesive tapes, but the present invention is not limited to these examples.

When the adhesive sheet of the present invention is an adhesive sheet in which an adhesive layer is formed on one surface of a base material and an adhesive layer having an adhesive force different from that of the adhesive layer is formed on the other surface, the adhesive sheet Among them, polyethylene terephthalate is preferred from the viewpoint of preventing migration of the plasticizer. Furthermore, when applying the pressure-sensitive adhesive sheet of the present invention to an adherend having a curved surface, a (meth)acrylic polymer having a crosslinked structure is preferable because it easily follows the curved surface, and a carboxyl group and/or primary amino group is preferable. Polymethyl methacrylate (PMMA) having a crosslinked structure is more preferable.

Examples of methods for applying the adhesive of the present invention to a base material include methods such as a knife coater, slot die coater, lip coater, roll coater, flow coater, spray coater, bar coater, and dipping. is not limited to these examples. When applying the adhesive of the present invention to a base material, the adhesive of the present invention may be applied directly to the base material, or after being applied to release paper etc. The adhesive layer may be transferred onto the substrate.

After applying the adhesive of the present invention to a substrate, it can be dried by a drying method such as a hot air drying method or a drying method using far-infrared irradiation, thereby forming an adhesive layer on the substrate. The thickness of the adhesive layer after drying is not particularly limited, but is usually 5 to 500 μm, preferably 10 to 250 μm.

The pressure-sensitive adhesive sheet of the present invention is obtained in the manner described above. The adhesive strength of the adhesive layer of the adhesive sheet of the present invention at 25°C cannot be determined unconditionally because it varies depending on the type of adherend, but from the viewpoint of preventing it from easily separating from the adherend, it is preferably 3 g/25 mm or more, more preferably 5 g/25 mm or more, and from the viewpoint of improving releasability to the adherend, preferably 100 g/25 mm or less, more preferably 90 g/25 mm or less, even more preferably 80 g/25 mm or less. be. Note that the adhesive strength of the adhesive layer of the adhesive sheet at 25° C. is a value measured based on the method described in the following examples.

A release sheet may be attached to the adhesive layer of the adhesive sheet of the present invention. When the release sheet is bonded to the surface of the adhesive layer in this way, the adhesive layer can be suitably protected. The release sheet may be a release sheet in which a mold release agent is applied to both sides of a base material and has a release surface on both sides, or a release sheet in which a mold release agent is applied to one side of the base material and a release surface is formed on the one side. It may also be a release sheet having the following properties. Among these, a release sheet with release surfaces on both sides is one in which an adhesive is applied to one surface of the release sheet with release surfaces on both sides, and after drying, another layer is applied on the surface of the formed adhesive layer. It has the advantage that there is no need to attach a release sheet. The release sheet is peeled off from the surface of the adhesive layer when using the adhesive tape.

In addition, when an adhesive layer is formed on one side of a base material having a shape such as a sheet or tape shape, by applying a mold release agent to the back side of this base material and forming a mold release agent layer. When an adhesive sheet, adhesive tape, etc. is rolled into a roll with the adhesive layer inside, the adhesive layer comes into contact with the release agent layer on the back of the base material, so it can be used to protect or preserve the surface of the adhesive layer. You can

Examples of base materials used for release sheets include resin films made of polyolefin resins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, thermoplastic resins such as polystyrene, polyvinyl chloride, and cellophane; high-quality paper, kraft paper, Examples include papers such as crepe paper and glassine paper, but the present invention is not limited to such examples. Further, examples of the mold release agent include silicone mold release agents, (meth)acrylic acid long chain alkyl ester mold release agents, polyvinyl alcohol, and wax, but the present invention is not limited to such examples. It's not something you can do.

As explained above, the adhesive of the present invention has low tackiness, excellent air release properties and mechanical strength when the adhesive film is attached to an adherend, and has an adhesive layer that has oozing prevention properties. Form. Furthermore, since the adhesive sheet of the present invention has the above-mentioned adhesive layer, it has low adhesiveness and is excellent in air release properties, mechanical strength, and oozing prevention properties when the adhesive film is attached to an adherend. There is.

Therefore, the adhesive sheet of the present invention can be used, for example, as a protective film for liquid crystal panels, plasma displays, electroluminescence displays, etc., a protective film for steel plates, etc., a film (label) to be attached to glass products such as window glass, glass containers, etc. It can be used as

Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples.

Manufacturing example 1
In a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, a dropping funnel, and a stirrer, 100 parts of ethyl acetate (parts by mass, the same applies hereinafter), 42.3 parts of butyl acrylate, 3.23 parts of acrylic acid, 0.16 parts of 2-hydroxyethyl acrylate and 8.2 parts of vinyl acetate were added. 0.1 part of a peroxide-based polymerization initiator [manufactured by Nippon Oil & Fats Co., Ltd., trade name: Niper BMT-K40] was placed in the reaction vessel, and the mixture was reacted at 80° C. for 3 hours in a nitrogen gas atmosphere. Thereafter, 0.3 parts of an azo polymerization initiator [manufactured by Nippon Finechem Co., Ltd., trade name: ABN-E] was added into the reaction vessel, and the reaction was further carried out at 80°C for 3 hours to increase the weight average molecular weight. 570,000, a glass transition temperature of -39°C, an acid value of 47 mgKOH/g, and a hydroxyl value of 1.4 mgKOH/g [hereinafter referred to as (meth)acrylic polymer] A solution of acrylic polymer A] was obtained (non-volatile content: 35% by mass).

Manufacturing example 2
In a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, a dropping funnel, and a stirrer, 100 parts of ethyl acetate, 34.5 parts of 2-ethylhexyl acrylate, 39.1 parts of butyl acrylate, and 3.27 parts of acrylic acid were added. 1 part, 0.25 parts of 2-hydroxyethyl acrylate, and 4.8 parts of vinyl acetate. 0.1 part of a peroxide-based polymerization initiator [manufactured by Nippon Oil & Fats Co., Ltd., trade name: Niper BMT-K40] was placed in the reaction vessel, and the mixture was reacted at 80° C. for 3 hours in a nitrogen gas atmosphere. Thereafter, 0.3 parts of an azo polymerization initiator [manufactured by Nippon Finechem Co., Ltd., trade name: ABN-E] was added into the reaction vessel, and the reaction was further carried out at 80°C for 3 hours to increase the weight average molecular weight. 500,000, a glass transition temperature of -54°C, an acid value of 31 mgKOH/g, and a hydroxyl value of 1.4 mgKOH/g [hereinafter referred to as (meth)acrylic polymer A solution of acrylic polymer B] was obtained (non-volatile content: 45% by mass).

Manufacturing example 3
In a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, a dropping funnel, and a stirrer, 100 parts of ethyl acetate, 21.9 parts of 2-ethylhexyl acrylate, 43.5 parts of butyl acrylate, and 1.00 parts of acrylic acid were added. 1 part and 0.20 part of 2-hydroxyethyl acrylate. 0.1 part of a peroxide-based polymerization initiator [manufactured by Nippon Oil & Fats Co., Ltd., trade name: Niper BMT-K40] was placed in the reaction vessel, and the mixture was reacted at 80° C. for 3 hours in a nitrogen gas atmosphere. Thereafter, 0.3 parts of an azo polymerization initiator [manufactured by Nippon Finechem Co., Ltd., trade name: ABN-E] was added into the reaction vessel, and the reaction was further carried out at 80°C for 3 hours to increase the weight average molecular weight. 710,000, a glass transition temperature of -59°C, an acid value of 12 mgKOH/g, and a hydroxyl value of 1.4 mgKOH/g [hereinafter referred to as (meth)acrylic polymer] A solution of acrylic polymer C] was obtained (non-volatile content: 40% by mass).

Production example 4
In a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, a dropping funnel, and a stirrer, 100 parts of ethyl acetate, 10.5 parts of 2-ethylhexyl acrylate, 55.5 parts of butyl acrylate, and 0.53 parts of acrylic acid were added. 1 part and 0.20 part of 2-hydroxyethyl acrylate. 0.1 part of a peroxide-based polymerization initiator [manufactured by Nippon Oil & Fats Co., Ltd., trade name: Niper BMT-K40] was placed in the reaction vessel, and the mixture was reacted at 80° C. for 3 hours in a nitrogen gas atmosphere. Thereafter, 0.3 parts of an azo polymerization initiator [manufactured by Nippon Finechem Co., Ltd., trade name: ABN-E] was added into the reaction vessel, and the reaction was further carried out at 80°C for 3 hours to increase the weight average molecular weight. 470,000, a glass transition temperature of -57°C, an acid value of 6 mgKOH/g, and a hydroxyl value of 1.4 mgKOH/g [hereinafter referred to as (meth)acrylic polymer] A solution of acrylic polymer D] was obtained (non-volatile content: 40% by mass).

Note that the acid value and hydroxyl value are values measured by neutralization titration method based on the provisions of JIS K0070 (1992).

Example 1
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.25 equivalent], 120 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 5.72 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive force of the adhesive was measured based on the following adhesive force measurement method, and the adhesive force was 13 g/25 mm.

[Method of measuring adhesive strength]
Apply the adhesive to the base material [polyethylene terephthalate film (length: 50 cm, width: 50 cm, thickness: 25 μm)] with an applicator and dry it at a temperature of 100°C for 5 minutes to form an adhesive layer with a thickness of 30 μm. formed. A release film (a release polyethylene terephthalate film treated with silicone) was laminated onto this adhesive layer to obtain an adhesive sheet having one side as an adhesive surface.

An adhesive tape was produced by cutting the adhesive sheet obtained above into a rectangle with a length of 50 mm and a width of 25 mm. The release paper of the adhesive tape obtained above was peeled off, and a stainless steel plate with a polished surface was placed on the peeled surface. Thereafter, the stainless steel plate was attached to the peeling surface by moving a roll having a mass of 2 kg back and forth over the stainless steel plate, and was left standing at room temperature (25° C.) for 20 minutes. Thereafter, the adhesive tape was peeled from the stainless steel plate at a peeling angle of 180° and a peeling rate of 300 mm/min, and the peeling force (unit: g/25 mm) was measured.

Example 2
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.25 equivalent], 120 parts of bis(2-ethylhexyl adipate) as a plasticizer, isocyanate Adding 1.43 parts of a crosslinking agent [manufactured by Nippon Polyurethane Industries Co., Ltd., trade name: Coronate (registered trademark) L-55E] and 5.72 parts of acetylacetone [manufactured by Daicel Corporation] to the solution of A above. An adhesive was obtained.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 29 g/25 mm.

Example 3
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.25 equivalent], 120 parts of bis(2-butoxyethyl adipate) as a plasticizer, 1.43 parts of isocyanate crosslinking agent [manufactured by Nippon Polyurethane Industries Co., Ltd., trade name: Coronate (registered trademark) L-55E] and 5.72 parts of acetylacetone [manufactured by Daicel Corporation] were added to the above (meth)acrylic polymer. By adding it to the solution of A, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 26 g/25 mm.

Example 4
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount based on the carboxyl group possessed by (meth)acrylic polymer A: 0.25 equivalent], 120 parts of diisodecyl adipate and acetylacetone as plasticizers [Daicel Co., Ltd.] A pressure-sensitive adhesive was obtained by adding 5.72 parts of the (meth)acrylic polymer A to the solution of the (meth)acrylic polymer A.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 14 g/25 mm.

Example 5
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum alkyl acetoacetate diisopropylate [Kawaken Fine Chemical Co., Ltd.] was added as a metal chelate crosslinking agent. Co., Ltd., trade name: Alumichelate M] 1.31 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.10 equivalent], 120 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [ 1.43 parts of Coronate (registered trademark) L-55E manufactured by Nippon Polyurethane Industries Co., Ltd. and 2.62 parts of acetylacetone [manufactured by Daicel Corporation] were added to the solution of the (meth)acrylic polymer A. By doing so, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 30 g/25 mm.

Example 6
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum monoacetylacetonate bis(ethyl acetoacetate) was used as a metal chelate crosslinking agent. Manufactured by Kawaken Fine Chemical Co., Ltd., product name: Aluminum Chelate D] 2.09 parts [amount based on the carboxyl group possessed by (meth)acrylic polymer A: 0.20 equivalent], 120 parts of diisononyl adipate as a plasticizer, epoxy Add 0.029 parts of a crosslinking agent [manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: TETRAD-C] and 4.18 parts of acetylacetone [manufactured by Daicel Corporation] to the solution of the (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 11 g/25 mm.

Example 7
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group of (meth)acrylic polymer A: 0.25 equivalent], 180 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 5.72 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 11 g/25 mm.

Example 8
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group of (meth)acrylic polymer A: 0.25 equivalent], 15 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan Polyurethane Industries Co., Ltd., product name: Coronate (registered trademark) L-55E] 1.43 parts, epoxy crosslinking agent [Mitsubishi Gas Chemical Co., Ltd., product name: TETRAD-C] 0.143 parts, and acetylacetone [Manufactured by Daicel Corporation] 5.72 parts was added to the solution of the (meth)acrylic polymer A to obtain an adhesive.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 62 g/25 mm.

Example 9
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 8.57 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.75 equivalent], 120 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 17.14 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Industries Co., Ltd. and 17.14 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 9 g/25 mm.

Example 10
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris (acetylacetonate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: aluminum chelate A] 3.75 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.35 equivalent], 120 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 7.5 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of the (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 11 g/25 mm.

Example 11
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 1.14 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.10 equivalent], 120 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Industries Co., Ltd. and 2.28 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of the (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 40 g/25 mm.

Example 12
Per 100 parts of (meth)acrylic polymer B contained in the solution of (meth) acrylic polymer B obtained in Production Example 2, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 9.78 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 1.28 equivalents], 80 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Industries Co., Ltd. and 19.56 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer B. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 16 g/25 mm.

Example 13
Per 100 parts of (meth)acrylic polymer C contained in the solution of (meth) acrylic polymer C obtained in Production Example 3, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.12 parts [amount based on the carboxyl group of (meth)acrylic polymer A: 0.76 equivalent], 30 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 4.24 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer C. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 78 g/25 mm.

Comparative example 1
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.25 equivalent], adipic acid polyester [J-Co., Ltd.] as a polymer plasticizer. Made by Plas, product number: D643, molecular weight: approximately 1800] 120 parts, isocyanate crosslinking agent [made by Japan Polyurethane Industries Co., Ltd., product name: Coronate (registered trademark) L-55E] 1.43 parts, and acetylacetone [Co., Ltd.] A pressure-sensitive adhesive was obtained by adding 5.72 parts (manufactured by Daicel) to the solution of the (meth)acrylic polymer A.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 250 g/25 mm.

Comparative example 2
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.25 equivalent], diisononyl phthalate as an aromatic plasticizer [Mitsubishi Chemical Co., Ltd.] product, product number: DINP] 120 parts, isocyanate crosslinking agent [Japan Polyurethane Industries Co., Ltd., product name: Coronate (registered trademark) L-55E] 1.43 parts, and acetylacetone [Daicel Corporation] 5.72 parts % to the solution of the (meth)acrylic polymer A to obtain an adhesive.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 120 g/25 mm.

Comparative example 3
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, 120 parts of diisononyl adipate as a plasticizer and an isocyanate-based crosslinking agent [Japan Polyurethane Industry Co., Ltd. Co., Ltd., trade name: Coronate (registered trademark) L-55E] was added to the solution of the (meth)acrylic polymer A to obtain an adhesive.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 450 g/25 mm.

Comparative example 4
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, 120 parts of diisononyl adipate as a plasticizer and an epoxy crosslinking agent [Mitsubishi Gas Chemical ( A pressure-sensitive adhesive was obtained by adding 0.143 parts of TETRAD-C, manufactured by Co., Ltd., trade name: TETRAD-C, to the solution of the (meth)acrylic polymer A.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 180 g/25 mm.

Comparative example 5
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount relative to the carboxyl group of (meth)acrylic polymer A: 0.25 equivalent], 225 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 5.72 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 8 g/25 mm.

Comparative example 6
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 2.86 parts [amount based on the carboxyl group of (meth)acrylic polymer A: 0.25 equivalent], 5 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 5.72 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 500 g/25 mm.

Comparative example 7
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 11.43 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.99 equivalent], 120 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Kogyo Co., Ltd. and 22.86 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 8 g/25 mm.

Comparative example 8
Per 100 parts of (meth)acrylic polymer A contained in the solution of (meth) acrylic polymer A obtained in Production Example 1, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 0.57 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer A: 0.05 equivalent], 120 parts of diisononyl adipate as a plasticizer and an isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Industries Co., Ltd. and 1.14 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of (meth)acrylic polymer A. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive force of the adhesive was measured in the same manner as in Example 1, and the adhesive force was 80 g/25 mm.

Comparative example 9
Per 100 parts of (meth)acrylic polymer D contained in the solution of (meth) acrylic polymer D obtained in Production Example 4, aluminum tris(ethyl acetoacetate) [Kawaken Fine Chemical Co., Ltd.] was used as a metal chelate crosslinking agent. Co., Ltd., product number: ALCH-TR] 1.12 parts [amount relative to the carboxyl group possessed by (meth)acrylic polymer D: 0.79 equivalent], 30 parts of diisononyl adipate as a plasticizer, isocyanate crosslinking agent [Japan 1.43 parts of Coronate (registered trademark) L-55E manufactured by Polyurethane Industries Co., Ltd. and 2.24 parts of acetylacetone [manufactured by Daicel Corporation] are added to the solution of the (meth)acrylic polymer D. In this way, an adhesive was obtained.

Using the adhesive obtained above, the adhesive strength of the adhesive was measured in the same manner as in Example 1, and the adhesive strength was 320 g/25 mm.

Next, the following physical properties were evaluated using the adhesives obtained in each Example and each Comparative Example. The results are shown in Table 1.

First, an adhesive is applied to a base material [polyethylene terephthalate film (length: 60 cm, width: 60 cm, thickness: 25 μm)] using an applicator, and the thickness is reduced to 30 μm by drying at a temperature of 100°C for 5 minutes. An adhesive layer was formed. A release film (a release polyethylene terephthalate film treated with silicone) was laminated onto this adhesive layer to obtain an adhesive sheet having one side as an adhesive surface.

(1) Air release performance Air release performance was evaluated based on the schematic explanatory diagram of the air release performance evaluation method shown in FIG. More specifically, the base of an adhesive sheet 2 (length: 60 mm, width: 60 mm) is placed on a smooth glass plate 1 with a side length of 80 mm so that the adhesive layer 3 of the adhesive sheet 2 is on the top surface. After fixing the material 4, align the short side of the adhesive layer 3 with the short side of the polyethylene terephthalate film 5 (length: 50 mm, width: 25 mm, thickness: 0.1 mm), and attach the polyethylene terephthalate film (hereinafter referred to as polyester film). ) A region 2 mm from the end of the short side of No. 5 was attached to the adhesive layer, and the other short side was held with fingers.

Next, gently release the edge of the polyester film 5 that you were holding with your fingers, and use a video camera to photograph the situation until the entire surface of the polyester film 5 sticks to the adhesive layer 3. Based on this, the time from when the end of the polyester film 5 is released from the hand until the polyester film 5 sticks to the adhesive layer 3 is measured, and the length (58 mm) of the polyester film 5 is calculated as follows: The air release speed was determined by dividing by the time it took to stick.

In addition, whether or not air bubbles were present between the adhesive layer 3 and the polyester film 5 was visually confirmed.

Based on the above results, air release performance was evaluated according to the following evaluation criteria.
〔Evaluation criteria〕
◎: No air bubbles are observed between the adhesive layer 3 and the polyester film 5, and the air release rate is 10 mm/sec or more.
Good: No air bubbles are observed between the adhesive layer 3 and the polyester film 5, and the air release rate is 6 mm/sec or more and less than 10 mm/sec.
Δ: No air bubbles were observed between the adhesive layer 3 and the polyester film 5, and the air release rate was less than 6 mm/sec.
x: The presence of air bubbles is observed between the adhesive layer 3 and the polyester film 5.

(2) Strength of adhesive layer Measured according to the pencil scratch test of JIS K5400-8-4. In addition, a pencil with a hardness of 6B was used as the pencil, the mass of the weight was 200 g, the adhesive layer was visually observed when the adhesive layer was scratched with the pencil, and the strength of the adhesive layer was evaluated based on the following evaluation criteria. did.
〔Evaluation criteria〕
◎: No scratches or falling off of the adhesive layer was observed.
Good: Scratches are observed on the adhesive layer, but no peeling of the adhesive layer is observed.
×: Scratches on the adhesive layer and falling off of the adhesive layer are observed.

(3) Leakage inhibiting property After evaluating the above-mentioned "air release property", the polyester film was peeled off from the adhesive sheet, the polyester film was visually observed, and the seepage inhibiting property was evaluated based on the following evaluation criteria.

〔Evaluation criteria〕
◎: No exudate is observed on the surface of the polyester film.
○: Slight exudate is observed on the surface of the polyester film.
Δ: Exudates are observed on the surface of the polyester film, but transparency is maintained.
×: Transparency of the polyester film is lost.

In addition, in the evaluation of the physical properties of a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet that has even one evaluation of "x" is rejected.

From the results shown in Table 1, in each Example, the acid value of the carboxyl group-containing (meth)acrylic polymer was 10 mgKOH/g or more, and the carboxyl group-containing (meth)acrylic polymer and the metal chelate crosslinking agent Because the adhesive sheet is used in combination with It can be seen that it is excellent.

Example 14
Per 100 parts of aminoethylated acrylic polymer [manufactured by Nippon Shokubai Co., Ltd., trade name: Polyment NK-380], 17.1 parts of crosslinking agent [manufactured by Nagase ChemteX Co., Ltd., trade name: Deconal EX-931] and as a solvent. A resin composition was prepared by mixing the aminoethylated acrylic polymer, the crosslinking agent, and ethyl acetate in a ratio of 150 parts of ethyl acetate. The resin composition obtained above was applied onto a release film using an applicator and dried at a temperature of 100° C. for 3 minutes to obtain a base material having a methacrylic polymer layer with a thickness of 1.5 μm.

Next, using the adhesive obtained in Example 1, a slightly adhesive layer (thickness: 50 μm) was formed on the methacrylic polymer layer of the base material in the same manner as in Example 1. A release film was attached to this slightly adhesive layer to obtain an adhesive sheet in which one side of the isolation layer was an adhesive surface.

Acrylic adhesive at a ratio of 0.30 parts of crosslinking agent [manufactured by Soken Kagaku Co., Ltd., product number: E-AX] to 100 parts of acrylic adhesive [manufactured by Soken Kagaku Co., Ltd., product name: SK Dyne 2094]. An adhesive for a strong adhesive layer was prepared by mixing the agent and the crosslinking agent.

The adhesive for a strong adhesive layer obtained above was applied to a release film (thickness: 50 μm) using an applicator and dried at a temperature of 90° C. for 2 minutes to form a strong adhesive layer with a thickness of 50 μm. Ta.

The non-adhesive surface of the adhesive sheet, in which one side of the base layer is the adhesive surface, was bonded to the strong adhesive layer obtained above to produce a double-sided adhesive tape. When the adhesive force of the slightly adhesive layer of the double-sided adhesive tape obtained above was examined in the same manner as in Example 1, the adhesive force was 15 g/25 mm. Furthermore, when the adhesive strength was examined in the same manner as in Example 1 after one month, the adhesive strength was 15 g/25 mm, so no change was observed in the adhesive strength, and no oozing of the plasticizer was observed. .

Using the double-sided adhesive tape obtained above, the air release property of the slightly adhesive layer was examined in the same manner as above, and the air release property was evaluated as ◎.

1 Glass plate 2 Adhesive sheet 3 Adhesive layer 4 Base material 5 Polyester film

Claims (4)

An adhesive containing a carboxyl group-containing (meth)acrylic polymer, a metal chelate crosslinking agent , a plasticizer , and a crosslinking agent , wherein the carboxyl group-containing (meth)acrylic polymer has an acid value of 10 mgKOH/g or more. , the amount of plasticizer per 100 parts by mass of the carboxyl group-containing (meth)acrylic polymer is 10 to 200 parts by mass, and the amount of the metal chelate crosslinking agent for the carboxyl group of the carboxyl group-containing (meth)acrylic polymer is the amount of the metal chelate crosslinking agent is 0.1 equivalent or more, the amount of the metal chelate crosslinking agent is 9.78 parts by mass or less per 100 parts by mass of the carboxyl group-containing (meth)acrylic polymer, and the plasticizer is an aliphatic 1. A pressure-sensitive adhesive , which is a dicarboxylic acid diester, and the crosslinking agent is at least one crosslinking agent selected from the group consisting of an isocyanate crosslinking agent and an epoxy crosslinking agent . A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 1 formed on at least one surface of a base material. A double-sided adhesive in which an adhesive layer made of the adhesive according to claim 1 is formed on one surface of a base material, and an adhesive layer having a different adhesive force from that of the adhesive layer is formed on the other surface of the base material. sheet. The double-sided pressure-sensitive adhesive sheet according to claim 2 , wherein the base material is made of a (meth)acrylic polymer having a crosslinked structure.

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