JP4644576B2 - Alkali film removal type water-based adhesive - Google Patents

Description

The present invention relates to a surface treatment agent for metals having adhesion performance in water. More specifically, the present invention relates to a metal surface treatment agent having a film formed on the metal surface using the surface treatment agent, having excellent adhesion regardless of the polarity of other adhesives, and having good alkali film removal properties.

Conventionally, chromate steel plates and steel materials that have been electroplated and hot-dip galvanized and further chromed have been used for steel plates and steel materials used in home appliances, automobiles, building materials, and the like. Since the chromate steel plate has been regarded as a problem because it uses hexavalent chromium, which has been pointed out as carcinogenic, liver failure, skin disorder, etc., it has recently been replaced by a non-chromate steel plate that does not use these. Yes. In manufacturing such a non-chromate steel sheet, a technique for improving the corrosion resistance by applying an inorganic or organic film treatment instead of the chromium treatment has been developed, and various applied technologies have been proposed. Patent Document 1 discloses performing an organic film treatment for improving the workability of a metal steel sheet, and Patent Document 2 discloses a technique using an organic film process as a primer for adhesion to a specific organic resin. Further, Patent Document 3 discloses a technique for applying an organic film treatment for bonding with an organic adhesive used in automobile manufacture. As these disclosed technologies show, the organic film used in the current metal surface treatment technology is not only adhesive with metal, but also with organic compounds such as resins and adhesives so that it can be used for various subsequent processing. It has been required to have adhesiveness.

Under such a technical background, resins such as acrylic, epoxy, and urethane have been applied as resins that have been used for organic coatings. The organic film of acrylic resin, which is relatively advantageous, is frequently used. On the other hand, in order to improve the adhesiveness when an adhesive is applied to the organic film, the adhesive resin and the organic film need to be sufficiently bonded by chemical action, but when using the acrylic resin film, There is a problem that the adhesiveness changes depending on the presence / absence / magnitude of the polarity of the adhesive resin. In order to solve such problems, a copolymer of acrylic acid and / or methacrylic acid and acrylic acid ester and / or methacrylic acid ester has an acid value of 40 to 100 and a glass transition temperature of 30 ° C. to 60 ° C. A metal surface treatment technique capable of alkali film removal using an acrylic resin is disclosed (Patent Document 4). Since alkali film removal is possible, there is also an advantage that electrodeposition coating used in the automobile industry and the like becomes easy.

However, in order to further improve the adhesion to metal and the film removal property in an alkaline environment, the acrylic organic film increases the number of carboxyl groups in the molecule and increases the polarity (that is, increases the acid value). However, when the disclosed technique is applied, if the acid value is higher than 100, there is a problem in that the adhesiveness with the nonpolar adhesive deteriorates and the processing is hindered.

JP 2003-138385 A Japanese Patent No. 31965634 Japanese Patent No. 3343842 Japanese Patent No. 3088948

The problem to be solved by the present invention is that when a film is formed on a metal surface, they can be bonded using various adhesives without being affected by the presence or absence of the polarity of the adhesive resin, and the alkali film-removing property is improved. It is to provide an aqueous adhesive having the same.

In such a situation, the present inventors conducted extensive studies, and as a result, (A) a structural unit derived from an α, β-ethylenically unsaturated carboxylic acid, and (B) an α, β-ethylenically unsaturated carboxylic acid ester. An alkaline film-removable water-based adhesive comprising a structural unit derived from (C) a polymer essentially containing a structural unit derived from diacetone acrylamide, and ( C) The content of the structural unit derived from diacetone acrylamide is 0.5 to 50% by mass, and the present invention has been completed by finding that an alkaline film-removable aqueous adhesive can solve the above-mentioned problems .

When a film is formed on the metal surface by using the alkaline film removal type aqueous adhesive of the present invention, they can be bonded using various adhesives without being affected by the presence or absence of the polarity of the adhesive resin, And good alkali film removal property can be provided.

The (A) α, β-ethylenically unsaturated carboxylic acid according to the present invention is not particularly limited, but monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and isocrotonic acid, maleic acid, fumaric acid, itaconic acid And the like. Among these, monocarboxylic acid is preferable, and methacrylic acid is more preferable in terms of adhesiveness. These α, β-ethylenically unsaturated carboxylic acids can be used singly or in combination of two or more.

(A) The amount of the structural unit derived from the α, β-ethylenically unsaturated carboxylic acid is preferably when the polymer is taken as 100% by mass from the viewpoint of film removal after forming a film on the metal surface. Is 20% by mass or more, more preferably 30% by mass or more, and preferably 40% by mass or less.

The (B) α, β-ethylenically unsaturated carboxylic acid ester according to the present invention is not particularly limited, and examples thereof include acrylic acid esters and methacrylic acid esters. Specific acrylic acid esters include acrylic acid. Methyl, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isobornyl acrylate, N, N-dimethylaminoethyl acrylate, isobutyl acrylate, 4-hydroxybutyl acrylate, acrylic 2-methoxyethyl acid, 3-methoxybutyl acrylate, lauryl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane acrylate, 1,9-nonanediol acrylate, 2-hydroxyethyl acrylate 2-acrylic acid Rokishipuropiru and the like. Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, alkyl methacrylate. , Tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, allyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, methacrylic acid 2 -Methoxyethyl, 2-ethoxyethyl methacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, dimethyl 1,6-hexanediol of crylic acid, polypropylene glycol dimethacrylate, trimethylolpropane trimethacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, trifluoroethyl methacrylate, heptadecafluorodecyl methacrylate, etc. One type or two or more types are selected and used as necessary.

Further, the amount of the structural unit derived from (B) α, β-ethylenically unsaturated carboxylic acid ester in the polymer is not particularly limited, but the balance between the content of diacetone acrylamide and adhesiveness, From the viewpoint of the water-soluble / water-insoluble balance of the coalescence, it is preferably 50 to 70% by mass.

The preferred content in the polymer of the structural unit derived from (C) diacetone acrylamide according to the present invention is in the range of 0.5 to 50% by mass, but more preferably it can balance adhesion and film removal. .5 to 20% by mass. If it is 0.5% by mass or less, the adhesive ability may be lowered, and if it is 50% by mass or more, the water solubility is lowered and the film removal property is lowered.

In addition, (C) diacetone acrylamide according to the present invention may be used in combination with diacetone acrylamide alone or in combination with diacetone acrylamide depending on the degree of adhesion required in various applications. Other acrylamide monomers include acrylamide, N, N-dimethylacrylamide, Nn-butoxyacrylamide, oleic acid amide, N, N-dimethylacetamide, N- [3- (dimethylamino) propyl] acrylamide, etc. Depending on, one type or two or more types are selected and used.

  The alkaline film-removable water-based adhesive according to the present invention, that is, the alkali film-removable water-based adhesive comprising a polymer composed of various structural units (A), (B) and (C), the acid value of the polymer Is not particularly limited, but is preferably greater than 100 and less than or equal to 300 from the viewpoint of film removal properties. This is 1.79 to 5.35 in terms of the amount of carboxyl groups in 1 g of the polymer. It corresponds to about millimolar.

The alkaline film-removable aqueous adhesive according to the present invention, that is, the alkali film-removable water-based adhesive comprising a polymer comprising various structural units (A), (B) and (C), the glass transition of the polymer Although there is no restriction | limiting in particular in temperature, From a viewpoint of workability improvement, Preferably it is -40-100 degreeC, More preferably, it is the range of 0-60 degreeC.

  The production method of the alkaline film-removable aqueous adhesive of the present invention is not particularly limited, and publicly known methods can be used. Specifically, a temporary charging method, a monomer addition method, a monomer emulsion addition method, a seed type Conventional methods such as a polymerization method may be mentioned. An organic solvent for improving the wettability of a metal material or the like and further providing an antifoaming effect can be blended. Preferred organic solvents include methanol, ethanol, isopropanol, butanols, hexanol, 2-ethylhexanol, ethylene glycol ethyl ether or butyl ether, diethylene glycol, propylene glycol, etc., but are not limited to these. Or may be used in combination of two or more.

  In the production of the present invention, a surfactant may be used as an emulsification aid. As the surfactant to be used in this case, known and publicly available surfactants such as nonions, anions, and cations can be used according to the purpose, but it is desirable to select the kind and the amount to be used that do not inhibit the expression of the effect of the invention. . Nonionic activators include polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene dodecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene isoester Stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene 2-ethyl-hexyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ether (synthetic system), narrow type polyoxyethylene alkyl ether, polyoxyethylene octyldodecyl (gel) Be) ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene β-naphthyl ether, poly Examples include oxyethylene hydrogenated castor oil ether, polyethylene glycol monoalkyl fatty acid ester, polyethylene glycol dialkyl fatty acid ester, polyoxyethylene sorbitan monolauric acid ester and the like, but anionic activators in addition to nonionic activators for the purpose of obtaining stable polymers. Etc. may be used in combination. Semi-cured tallow fatty acid soap Na salt, stearic acid soap Na salt, oleic acid soap K salt, gum rosin disproportionated rosin sodium salt, alkenyl succinic acid dipotassium salt, dodecyl sulfate Na salt, polyoxyethylene Alkyl (C12, C13) ether sulfate Na salt, polyoxyethylene dodecyl sulfate ammonium salt, dodecyl benzene sulfonate Na salt, higher alkyl monoamine salt, dialkylethyl methyl ethyl sulfate ammonium salt and the like as cation activator are mentioned. Most preferably, reactive surfactants are used for the purpose of preventing loss of the adhesive properties of the invention. Examples of the reactive surfactant include polyoxyethylene alkylphenyl ether and its sulfate ester salt, sulfosuccinic acid type, alkenyl polyoxyalkylene phosphate ester, polyoxyethylene alkyl ammonium phosphate glycidyl ether adduct, and the like. Further, a protective colloid such as polyvinyl alcohol may be used as a substitute for the surfactant.

    As polymerization initiators, azo-based azobisisobutyronitrile and its hydrochloride, 4,4′-azobis (4-cyanovaleric acid), persulfates, potassium persulfate, sodium persulfate, ammonium persulfate, Examples include sodium persulfate.

  Moreover, when neutralizing the polymer obtained using the above production method, as a neutralizing agent to be used, sodium hydroxide, potassium hydroxide, barium hydroxide, lithium hydroxide, or a divalent metal Includes alkalis such as zinc oxide and calcium hydroxide. Further, amines can also be used, such as triethylamine, N, N-dimethylbutylamine, N, N-dimethylallylamine, N-methylpyrrolidine, tetramethyldiaminomethane, trimethylamine, etc. Secondary amines such as N-methylethylamine, diisopropylamine , Diethylamine, primary amines include propylamine, t-butylamine, sec-butylamine, isobutylamine, 1,2-dibutylpropylamine, 3-pentylamine, etc., and morpholine-based morpholine, N-methylmorpholine, N- Ethylmorpholine, piperazine as piperazine, hydroxyethylpiperazine, 2-methylpiperazine, aminoethylpiperazine, aminoalcohol as N, N-diethylethanolamine, N, N-dibutylethanol Ruamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, Nn-butylethanolamine, Nn-butyldiethanolamine, Nt-butyl Ethanolamine, Nt-butyldiethanolamine, N- (β-aminoethyl) isopropanolamine, N, N-diethylisopropanolamine, 2-amino-2-methyl-1-propanol and the like, and diamines include ethylenediamine, diethylenetriamine, Ethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylethanolamine, 1,6-hexamethylenediamine, metaxylylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, and coconut amine as an aliphatic amine , Octylamine, laurylamine, stearylamine, and the like oleylamine and their EO adducts.

When neutralizing the polymer, the pH of the aqueous adhesive containing the polymer is preferably 4 or more, more preferably 5 or more, and preferably 9 or less, more preferably 6 or less. From the viewpoint of film removal properties, etc., it is preferable.

The alkali film-removing water-based adhesive of the present invention can be adjusted for film-removability, lubricity, and workability by controlling the average molecular weight of the polymer contained therein. An appropriate molecular weight range is preferably a number average molecular weight of 10,000 or more, more preferably 12,000 or more, further preferably 15,000 or more, preferably 30,000 or less, more preferably 25,000 or less, Preferably it is 20,000 or less.

In order to increase the molecular weight of the polymer, it is possible to reduce the initiator amount and the polymerization temperature. In order to reduce the molecular weight, it is possible to increase the amount of the initiator and increase the polymerization temperature. Further, the molecular weight can be controlled by using a chain transfer agent. Specifically, benzene, toluene, ethylbenzene, isopropylbenzene, diphenylmethane, triphenylmethane, acetone, methyl ethyl ketone, cyclohexanone, isobutyl alcohol, ethyl acetate, isopropyl alcohol, and compounds having a thiol group, lauryl mercaptan, 2-mercaptoethyl alcohol , Dodecyl mercaptan, mercaptosuccinic acid, n-butyl mercaptopropionate, octyl mercaptopropionate, butyl mercaptopropionate, and the like. These chain transfer agents are preferably mixed in advance with the monomer emulsion to be dropped and dropped into the reaction vessel.

Moreover, the alkali film-removal type water-based adhesive of the present invention can be used by adding various additives in a range not impairing the effects of the present invention depending on the application. For example, colloidal silica is added to improve lubricity at the time of coating a steel sheet, and wax, fluororesin or an aqueous dispersion thereof is mixed to further improve lubricity and film removal properties.

When using the alkaline film removal type aqueous adhesive of the present invention, for example, a polymer containing the components (A), (B) and (C) as essential constituent units, and optionally colloidal silica, wax and / or Or fluororesin, and other additives as long as they do not impair the effects of the present invention (for example, anti-leathering agents, leveling agents, antifoaming agents, penetrating agents, emulsifying agents, film-forming aids, color pigments, thickeners) It is recommended to first prepare an aqueous adhesive composition comprising) and then apply it to a metal surface.

The non-volatile content concentration of the alkali film-removing aqueous adhesive of the present invention is preferably 10 to 20% by mass. There is no particular limitation on the method of applying the aqueous adhesive to the steel sheet, and examples thereof include a roll coater method, a spray method, and a curtain flow coater method. After apply | coating a water-system adhesive agent to a steel plate, it can dry by a well-known method. The drying temperature is preferably 80 to 200 ° C, more preferably 100 to 150 ° C, and the drying time is preferably 1 to 2 minutes.

The adhesion amount of the water-based adhesive to the steel plate is preferably 0.2 to 3.0 g / m ² , more preferably 1.0 to 2.0 g / m ² (after drying), from the balance of adhesion and film removal properties. ). In forming the film, it can be formed on only one side or both sides of the steel plate. The steel sheet to which the aqueous adhesive of the present invention is applied may be subjected to a known surface treatment such as plating treatment or chemical conversion treatment. Examples of the steel plate include a cold-rolled steel plate, an alloyed hot-dip galvanized steel plate, a hot-dip galvanized steel plate, and an electrogalvanized steel plate.

Hereinafter, the present invention will be described in more detail based on examples. However, this invention is not restrict | limited at all by these Examples.

Example 1: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution completely dissolved in 200 g of water, 10 g of diacetone acrylamide, 27.3 g of 2-ethylhexyl acrylate, 102.7 g of ethyl acrylate, and 60 g of methacrylic acid are diluted with 200 g of water, and the reactive surface activity is further obtained. A monomer emulsion obtained by emulsifying 15 g of the additive latemul S-180 (manufactured by Kao Corporation) was added dropwise simultaneously over 1 hour using a dropping funnel. After completion of dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150 mesh wire netting to obtain the aqueous adhesive-1 of the present invention.

Example 2: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution completely dissolved in 200 g of water, 10 g of diacetone acrylamide, 130.0 g of 2-ethylhexyl acrylate, and 60 g of methacrylic acid were diluted with 200 g of water, and the reactive surfactant Latemul S-180 (Kao) A monomer emulsion obtained by emulsifying 15 g of Co., Ltd. was added dropwise using a dropping funnel over 1 hour. After completion of dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150-mesh wire mesh to obtain the aqueous adhesive-2 of the present invention.

Example 3: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution completely dissolved in 200 g of water, 5 g of diacetone acrylamide, 56.1 g of 2-ethylhexyl acrylate, 58.9 g of n-butyl acrylate, and 80 g of methacrylic acid are diluted with 200 g of water and further reactive. A monomer emulsion obtained by emulsifying 15 g of surfactant Latemulu S-180 (manufactured by Kao Corporation) was added dropwise simultaneously over 1 hour using a dropping funnel. After completion of the dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150 mesh wire mesh to obtain the aqueous adhesive-3 of the present invention.

Example 4: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution in which 200 g of water is completely dissolved, 10 g of diacetone acrylamide, 130 g of n-butyl methacrylate, and 60 g of acrylic acid are diluted with 200 g of water, and the reactive surfactant Latemulu S-180 (Kao Corporation) The monomer emulsion emulsified with 15 g of the product was added dropwise using a dropping funnel over 1 hour. After completion of the dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150-mesh wire mesh to obtain an aqueous adhesive-4 of the present invention.

Example 5: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution completely dissolved in 200 g of water, 10 g of diacetone acrylamide, 27.3 g of 2-ethylhexyl acrylate, 102.7 g of ethyl acrylate, and 60 g of methacrylic acid were diluted with 200 g of water, and the reactive surface activity was further obtained. A monomer emulsion obtained by emulsifying 15 g of the additive latemul S-180 (manufactured by Kao Corporation) was added dropwise simultaneously over 1 hour using a dropping funnel. After completion of the dropping, the mixture was aged at 80 ° C. for 1 hour, and then approximately 10 g of a 50% aqueous solution of triethylamine was gradually added dropwise until the pH reached 6, followed by aging for 30 minutes, then cooled to 40 ° C. and filtered through a 150 mesh wire mesh. The aqueous adhesive-5 of the present invention was obtained.

Example 6: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution in which 200 g of water is completely dissolved, 60 g of diacetone acrylamide, 80 g of 2-ethylhexyl acrylate, and 60 g of methacrylic acid are diluted with 200 g of water, and the reactive surfactant Latemul S-180 (Kao Corporation) The monomer emulsion emulsified with 15 g of the product was added dropwise using a dropping funnel over 1 hour. After completion of dropping, the mixture was aged at 80 ° C. for 1 hour, then cooled to 40 ° C. and filtered through a 150 mesh wire netting to obtain an aqueous adhesive-6 of the present invention.

Example 7: A 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 400 g of water, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution completely dissolved in 200 g of water, 2 g of diacetone acrylamide, 158 g of ethyl acrylate, and 40 g of methacrylic acid were diluted with 200 g of water, and the reactive surfactant Latemul S-180 (manufactured by Kao Corporation) was further diluted. The monomer emulsion emulsified with 15 g of each was added dropwise simultaneously using a dropping funnel over 1 hour. After completion of dropping, the mixture was aged at 80 ° C. for 1 hour, then cooled to 40 ° C. and filtered through a 150 mesh wire mesh to obtain an aqueous adhesive-7 of the present invention.

Comparative Example 1: 400 g of water was charged into a 1000 ml four-necked round bottom flask equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel and heated to 80 ° C. An aqueous initiator solution in which 4 g is completely dissolved in 200 g of water, 74.4 g of n-butyl methacrylate, 65.6 g of 2-ethylhexyl acrylate, and 60 g of methacrylic acid are diluted in 200 g of water, and the reactive surfactant lathemul A monomer emulsion prepared by adding 15 g of S-180 (manufactured by Kao Corporation) and emulsified was simultaneously added dropwise over 1 hour using a dropping funnel. After completion of dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150 mesh wire netting to obtain an aqueous adhesive-8.

Comparative Example 2: 400 g of water was charged into a 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution completely dissolved in 200 g of water, 140.0 g of ethyl acrylate, and 60 g of methacrylic acid are diluted with 200 g of water, and 15 g of a reactive surfactant Latemul S-180 (manufactured by Kao Corporation) is added. The monomer emulsion emulsified in this manner was simultaneously added dropwise using a dropping funnel over 1 hour. After completion of the dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150 mesh wire net to obtain an aqueous adhesive-9.

Comparative Example 3: 400 g of water was charged into a 1000 ml four-necked round bottom flask equipped with a stirrer, thermometer, reflux condenser and dropping funnel, heated to 80 ° C., and then ammonium persulfate 0.4 g An aqueous initiator solution in which 200 g of water is completely dissolved, 190.0 g of butyl methacrylate and 10 g of methacrylic acid are diluted with 200 g of water, and 15 g of a reactive surfactant Latemul S-180 (manufactured by Kao Corporation) is added. The monomer emulsion emulsified in this manner was simultaneously added dropwise using a dropping funnel over 1 hour. After completion of the dropping, the mixture was aged at 80 ° C. for 1 hour, cooled to 40 ° C., and then filtered through a 150 mesh wire net to obtain an aqueous adhesive-10.

Comparative Example 4: Water-based adhesive-11 Ethylene-acrylic acid copolymer emulsion
HYTEC S-3121 manufactured by Toho Chemical Industry Co., Ltd.

Comparative Example 5: Water-based adhesive-12 Styrene-maleic acid copolymer aqueous solution
SMA3000H made by Sartomer

The properties and physical properties of the production examples and comparative examples are summarized in Table 1 and Table 2 below. Tg is the amount of (A) to (C) in the polymer (mass fraction) and (A), (B) or (C), ignoring the amount of reactive surfactant in the polymer. It is the value calculated using the Tg of the homopolymer consisting of only.

(Preparation of test plate for evaluation)
(1) Metal plate used as a carrier:
Uses a chromium-free steel plate (25 x 100 mm).
(2) Water-based adhesive coating and drying conditions:
A treatment agent adjusted to a 20% by mass solution was coated on the steel plate with a bar coater # 3, dried at 105 ° C. for 2 minutes using a hot air circulating dryer, and then allowed to stand for one day.

(Performance evaluation)
(1) Alkali film removal property evaluation A 1% NaOH aqueous solution was prepared, and 500 g was weighed in a 500 cc beaker, immersed at a temperature of 40 ° C. for 2 minutes, and then lightly washed with tap water to visually observe the film removal state.
Evaluation criteria:
◎ Complete film removal 〇 Most of the film can be removed. △ Partial film removal.
× Not removed

(2) Adhesive evaluation (2-1) Adhesion with adhesive (adhesiveness with synthetic butadiene rubber adhesive)
Low polarity adhesive (synthetic butadiene rubber adhesive) with two water-based adhesive resin-coated steel sheets coated with rust-preventive oil at a ratio of 1.5 / m ² (adhesive area 25 × 25 mm) Adhesion amount after drying is 1.0 to 1.5 g / m ² ) and cured by heating at 170 ° C. for 20 minutes. Thereafter, the two bonded steel plates are allowed to cool to room temperature, and then pulled in a shear tensile tester in a direction parallel to the bonding surface at a tensile speed of 50 mm / min until the steel plates peel. In the peeled adhesive region (25 × 25 mm), the area ratio of the region that was interface fracture (breakage of the interface between the adhesive layer and the resin film) was measured visually, and evaluated according to the following criteria. Regions that are not interfacial failure are cohesive failure (destruction of the adhesive layer itself) or substrate failure on the steel sheet.

Evaluation criteria:
◎ Interfacial fracture area ratio <10%
〇 10% ≦ area ratio of interface fracture area <30%
△ 30% ≦ area ratio of interface fracture area <50%
× 50% ≦ area ratio of interface fracture region

(2-2) Adhesion with adhesive (adhesiveness with epoxy adhesive)
Two water-based adhesive resin-coated steel sheets coated with rust-preventing oil at a ratio of 1.5 / m ² are mixed with a high-polarity adhesive (epoxy-based adhesive) (after drying) so that the adhesion area becomes 25 × 25 mm. Adhesive adhesion amount of 1.0 to 1.5 g / m ² ) and cured by heating at 170 ° C. for 20 minutes. Thereafter, the two bonded steel plates are allowed to cool to room temperature, and then pulled in a shear tensile tester in a direction parallel to the bonding surface at a tensile speed of 50 mm / min until the steel plates peel. In the peeled adhesive region (25 × 25 mm), the area ratio of the region that was interface fracture (breakage of the interface between the adhesive layer and the resin film) was measured visually, and evaluated according to the following criteria. Regions that are not interfacial failure are cohesive failure (destruction of the adhesive layer itself) or substrate failure on the steel sheet.

Evaluation criteria:
◎ Interfacial fracture area ratio <10%
△ 10% ≦ area ratio of interface fracture area <50%
× 50% ≦ area ratio of interface fracture region

Table 3 shows the performance evaluation results.

From the results shown in Table 3, it is clear that the alkaline film-removing water-based adhesive of the present invention has good adhesiveness with an adhesive resin regardless of polarity and good alkali film-removing property.

Claims (4)

(A) Structural unit derived from α, β-ethylenically unsaturated carboxylic acid, (B) Structural unit derived from α, β-ethylenically unsaturated carboxylic acid ester, and (C) Configuration derived from diacetone acrylamide A polymer that essentially contains a unit, and a polymer containing (C) diacetone acrylamide in the polymer having a content of 0.5 to 50% by mass and an acid value of 130 or more. only containing, film removal water-based adhesive alkali, characterized in that it is subjected to a metal surface treatment with a bonding step by applying different adhesive from the polymer on the dry film. The alkali film-removing aqueous adhesive according to claim 1, wherein the polymer has a glass transition temperature of -40 to 100 ° C. 3. The alkaline film-removable aqueous adhesive according to claim 1 or 2, further neutralized with a neutralizing agent. It is an object for metal adhesion, The alkali film-removal type water-based adhesive according to any one of claims 1 to 3.