JP6041717B2 - Hydrophilic treatment agent and aluminum material surface-treated with the hydrophilic treatment agent - Google Patents

Description

  The present invention relates to a hydrophilic treatment agent applied to the surface of a substrate such as an aluminum material, and an aluminum material surface-treated with such a hydrophilic treatment agent, whereby a hydrophilic surface film having excellent hydrophilicity and water resistance can be obtained. The present invention relates to a chemical treatment agent.

The heat exchanger for an air conditioner such as an air conditioner is composed of aluminum fins with a thickness of about 0.1 mm overlapped at intervals of 1 to 2 mm. Water droplets adhere to the fins, block the passage of the wind, and if condensation further proceeds, water will fly out from the wind outlet, so a hydrophilic treatment agent is applied to prevent condensation.
Thus, since the hydrophilization treatment agent greatly affects the performance of an air conditioner or the like, various studies have been made.

In order to solve the above-mentioned problems, those using various modified polyvinyl alcohol resins (hereinafter referred to as PVA resins) have been proposed as hydrophilic treatment agents.
For example, a hydrophilization treatment agent using an oxyalkylene group-containing PVA resin (see Patent Document 1), a modified PVA resin having an N-vinyl lactam polymer in the side chain of the PVA resin, and a crosslinking agent are contained. A hydrophilic treatment agent (see Patent Document 2) has also been proposed.
Moreover, in order to improve the water resistance of a PVA-type resin film, the technique which uses a glyoxylate as a crosslinking agent with respect to an acetoacetylated PVA-type resin (henceforth AA-type PVA-type resin) is known. (See Patent Document 3)

JP 2002-285139 A WO2010 / 084896 JP 2010-077385 A

  However, when the PVA resin described in Patent Documents 1 and 2 is used as a hydrophilic treatment agent, the initial hydrophilicity is good, but the water resistance is poor, so that the PVA resin is eluted by long-term use. There was a tendency for the hydrophilicity to decrease. In general, it has been considered that when PVA is crosslinked, the degree of freedom of the hydroxyl group decreases, or the hydrophilicity decreases, making it unsuitable for a hydrophilic treatment agent.

  That is, an object of the present invention is to provide a hydrophilizing agent that forms a surface film having excellent surface hydrophilicity and excellent water resistance when applied to the surface of an aluminum substrate or the like.

As a result of intensive studies in view of the above circumstances, the present inventor has solved the above problems with a hydrophilizing agent containing an acetoacetyl group- and oxyalkylene group-containing PVA resin (A) and a crosslinking agent (B). The present invention has been completed.
As described above, the oxyalkylene group-containing PVA resin is a resin having excellent hydrophilicity, but has poor water resistance, and the AA-PVA resin has excellent water resistance by crosslinking, but is hydrophilic. Sex is scarce. By making both present in one polymer, water resistance maintains the performance of the cross-linked AA-PVA-based resin, and the hydrophilicity is surprisingly superior to that of an oxyalkylene group-containing PVA-based resin. I was able to get it.

  A surface film with good hydrophilicity and water resistance can be obtained by subjecting a base material such as an aluminum material to surface treatment using the hydrophilizing agent of the present invention.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.
Hereinafter, the present invention will be described in detail.

［Ｒ^１及びＲ^２は水素または炭素数１〜３のアルキル基、Ｘは単結合または結合鎖、ｎは正の整数を示す。］ [PVA resin (A) having acetoacetyl group and oxyalkylene group]
The PVA resin (A) having an acetoacetyl group and an oxyalkylene group used in the present invention has a vinyl alcohol unit obtained by saponifying vinyl acetate as a main structural unit, together with vinyl acetate units remaining without saponification. And a structural unit containing an acetoacetyl group and a structural unit containing an oxyalkylene group. Such a structural unit containing an acetoacetyl group is not particularly limited, and can be represented by, for example, the general formula (1). The structural unit containing an oxyalkylene group is represented by the general formula (2). Can be represented.

[R ¹ and R ² are hydrogen or an alkyl group having 1 to 3 carbon atoms, X is a single bond or a bond chain, and n is a positive integer. ]

X in the oxyalkylene group-containing structural unit represented by the general formula (2) is a hydrocarbon such as alkylene, alkenylene, alkynylene, phenylene, or naphthylene (these hydrocarbons are halogen such as fluorine, chlorine, bromine, etc.) _other, -O of in may be _{substituted) -, - (CH 2 O} ) m -, - (OCH 2) m -, - (CH 2 O) mCH 2 -, - CO -, - COCO-, _{-CO (CH 2) mCO -,} - CO (C 6 H 4) CO -, - S -, - CS -, - SO -, - SO 2 -, - NR -, - CONR -, - NRCO -, - _{CSNR -, - NRCS -, -} NRNR -, - HPO 4 -, - Si (OR) 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) 2 -, - _{OTi (OR) 2 -, -} OTi (OR) 2 O- -Al (OR)-, -OAl (OR)-, -OAl (OR) O-, etc. (R is each independently an arbitrary substituent, preferably a hydrogen atom or an alkyl group; An integer of 5). Among them, —CH ₂ O— is preferably used because the raw material monomer is easily available.

Content of the structural unit which has an acetoacetyl group of the PVA-type resin (A) of this invention is 0.1-10 mol% normally, Furthermore, it is 0.5-8 mol%, Especially 1-6 mol%. It is preferable that If the content of the acetoacetyl group is too small, the water resistance of the film tends not to be sufficiently obtained. If the content is too large, the hydrophilicity of the film tends to decrease.
The content of the oxyalkylene group is usually 0.3 to 5 mol%, more preferably 0.5 to 4 mol%, and particularly preferably 1 to 3 mol%. If the content of the oxyalkylene group is too small, the hydrophilicity of the film tends to decrease, and if it is too large, the strength of the film tends to decrease.

  The viscosity of a 4 mass% aqueous solution at 20 ° C. measured in accordance with JIS K6726 of the PVA resin (A) used in the present invention is usually 1.5 to 20 mPa · s, and further 4 to 12 mPa · s, In particular, 5 to 10 mPa · s is preferable. If the aqueous solution viscosity is too low, the water resistance of the film tends to decrease, and if it is too high, workability such as coating property tends to decrease. In addition, this 4 mass% aqueous solution viscosity is widely used as a parameter | index of the molecular weight of PVA-type resin.

  The average degree of polymerization of the PVA-based resin (A) used in the present invention is usually 300 to 4000, particularly 400 to 2000, and more preferably 500 to 1000. If the average degree of polymerization is too small, there is a tendency that a film having sufficient water resistance cannot be obtained or a sufficient crosslinking rate cannot be obtained. On the other hand, if the degree of polymerization is too large, the viscosity becomes too high. Coating tends to be difficult.

  The degree of saponification of such PVA-based resin is usually 75 to 99.9 mol%, more preferably 80 to 99.5 mol%, and particularly preferably 85 to 99.3 mol%. If the degree of saponification is too low, the solubility in water tends to decrease.

  The method for producing the PVA-based resin (A) used in the present invention is not particularly limited, but the method of simultaneously introducing both functional groups by copolymerization, the production of PVA having one functional group by copolymerization, and the like, Examples thereof include a method for introducing a functional group. Among them, there is a production method in which an acetoacetyl group is introduced by post-modification into an oxyalkylene group-containing PVA resin obtained by saponifying a copolymer of a monomer containing an oxyalkylene group and a vinyl ester monomer. Preferably used.

Below, the manufacturing method which manufactures an oxyalkylene group containing PVA-type resin by copolymerization, and makes this PVA-type resin contain an acetoacetyl group by post-modification is demonstrated.

  The oxyalkylene group-containing PVA resin can be generally obtained by copolymerizing a vinyl ester monomer and an oxyalkylene group-containing monomer and saponifying the resulting polymer. It can be produced by the method described in paragraphs [0042] to [0055] of 2008-163179.

  Further, in the present invention, in addition to the acetoacetyl group-containing monomer and the oxyalkylene group-containing monomer, other monomers are contained in an amount of about 0.1 to 10 mol% within a range not impairing the object of the present invention. It is also possible to use a PVA resin obtained by copolymerization. Examples of such monomers include α-olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, and the like. .

Next, a method for introducing an acetoacetyl group into the oxyalkylene group-containing PVA resin by a post reaction will be described.
The introduction of the acetoacetyl group by such post-reaction is performed by converting the hydroxyl group into acetoacetate by reacting the oxyalkylene group-containing PVA resin with diketene.
Such an acetoacetylation reaction is performed by, for example, a homogeneous reaction in which a PVA resin is uniformly dissolved in a solvent such as DMSO, or a heterogeneous reaction in which a liquid or gaseous diketene is reacted with a solid PVA resin. However, industrially, the latter heterogeneous reaction is preferably used because the product after the reaction can be easily separated and washed.

  The oxyalkylene group-containing PVA tree used for such a heterogeneous reaction preferably has a narrow particle size distribution, especially in the form of powder, because diketene is uniformly adsorbed and absorbed, reacts uniformly, and improves the reaction rate. . The particle size is preferably 7 mesh pass to 450 mesh on, more preferably 10 mesh pass to 450 mesh on, and particularly 10 mesh pass to 320 mesh on a JIS standard sieve.

  The oxyalkylene group-containing PVA resin may contain several percent of alcohols, esters and moisture in the production process, and these components react with diketene and consume diketene, Since there are some which lower the reaction rate of diketene, it is desirable to use it after reducing it as much as possible by carrying out a reaction such as heating and depressurization.

As a method of reacting the oxyalkylene group-containing PVA resin powder and the diketene, the PVA resin and the gaseous or liquid diketene may be directly reacted, or an organic acid is adsorbed and occluded in advance in the PVA resin powder. After that, a method of spraying and reacting liquid or gaseous diketene in an inert gas atmosphere or spraying and reacting a mixture of an organic acid and liquid diketene to an oxyalkylene group-containing PVA resin powder is used. .
Among them, such a method is preferably used because diketene penetrates quickly into the PVA resin by using a method of adsorbing and occluding an organic acid in the PVA resin.

Acetic acid is most preferable as such an organic acid, but is not limited thereto, and propionic acid, butyric acid, isobutyric acid and the like are arbitrarily used.
The amount of the organic acid is preferably within an amount that can be adsorbed and occluded by the oxyalkylene group-containing PVA resin powder in the reaction system, in other words, an amount that does not exist the organic acid separated from the resin in the reaction system, Although it is necessary to determine the addition amount in consideration of the amount of modification or the crystallinity of the PVA resin, specifically, it is 0.1 to 80 parts by weight, preferably 0 to 100 parts by weight of the PVA resin. It is appropriate that 5 to 50 parts by weight, particularly preferably 5 to 20 parts by weight of an organic acid coexist. If the amount of the organic acid is too small, it is difficult to obtain the effect of coexisting the organic acid. On the other hand, if the organic acid is excessive, a large amount of washing solvent is required to remove the organic acid after the reaction, which is not economical.

  In order to uniformly adsorb and occlude an organic acid on an oxyalkylene group-containing PVA resin, a method of spraying an organic acid alone onto the PVA resin, a method of dissolving an organic acid in an appropriate solvent, and spraying it are optional. The following means can be implemented.

  The reaction conditions of the oxyalkylene group-containing PVA resin and diketene are as follows. When the liquid diketene is uniformly adsorbed and absorbed by means such as spraying on the PVA resin powder, the temperature is 10 to 120 ° C. in an inert gas atmosphere. It is preferable to continue the stirring or the fluid state for a predetermined time.

When the diketene gas is reacted, the contact temperature is 20 to 250 ° C., preferably 40 to 200 ° C. The temperature at which the gaseous diketene does not liquefy at the time of contact with the oxyalkylene group-containing PVA resin and the diketene partial pressure condition It is preferable that the gas is in contact with the gas, but it is not a problem that some gas forms droplets.
The contact time depends on the contact temperature, that is, when the temperature is low, the time is long, and when the temperature is high, the time may be short, and is appropriately selected from the range of 1 minute to 6 hours.

  When supplying the diketene gas, the diketene gas may be used as it is, or a mixed gas of diketene gas and inert gas may be used. The oxyalkylene group-containing PVA resin may absorb the gas, and the temperature may be increased. It is preferable to contact the gas after heating while heating.

  As a catalyst for such a reaction, basic compounds such as sodium acetate, potassium acetate, primary amine, secondary amine and tertiary amine are effective, and 0.1 to 10% by weight based on the oxyalkylene group-containing PVA resin. It is. In addition, PVA-type resin contains sodium acetate as a by-product at the time of manufacture normally, and it is also possible to utilize it. On the other hand, if the amount of catalyst is too large, side reaction of diketene tends to occur, which is not preferable.

  As the reaction apparatus, any apparatus that can be heated and has a stirrer is used. For example, a kneader, a Henschel mixer, a ribbon blender, other various blenders, and a stirring and drying device.

[Crosslinking agent (B)]
Next, the crosslinking agent (B) of the present invention will be described.
The crosslinking agent (B) is not particularly limited, and examples thereof include inorganic crosslinking agents such as chromium compounds, aluminum compounds, zirconium compounds, and boron compounds, and aldehyde compounds such as glyoxylate and glyoxal; polyamides, polyamines, polyethyleneimines , Ethyleneimine compounds, hydrazine compounds, carbodiimide compounds, oxazoline compounds, isocyanate compounds and other nitrogen atom-containing compounds; epichlorohydrin and other epoxy compounds; urea resins, melamine resins and other N-methylol compounds; acryloyl compounds Acrylic compounds such as compounds; organic cross-linking agents such as active halogen compounds, metals, and metal complex salts can be used. Among them, an aldehyde compound is preferable in that a film excellent in water resistance can be obtained, and glyoxylate is preferably used in terms of stability when a mixed aqueous solution with the PVA resin (A) is used.

Examples of the glyoxylate include metal salts and amine salts of glyoxylic acid. Examples of the metal salt include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, titanium, zirconium, Transition metals such as chromium, manganese, iron, cobalt, nickel, copper, other metals such as zinc and aluminum and metal salts of glyoxylic acid, and amine salts include amines such as ammonia, monomethylamine, dimethylamine, and trimethylamine And salts of glyoxylic acid.
In particular, metal salts, particularly alkali metal and alkaline earth metal salts, are preferably used from the viewpoint of obtaining a crosslinked polymer having excellent water resistance.

  In addition, it is considered that the hydrophilicity of the carboxylate group introduced into the crosslinked structure is small compared to the carboxylic acid group, which contributes to the improvement of the water resistance of the crosslinked polymer. Glyoxylate having a lower solubility in water is preferable. Specifically, the solubility in water at 23 ° C. is 0.01 to 100%, particularly 0.1 to 50%, and further 0.5 to 20%. Is preferably used. For example, the solubility of sodium glyoxylate is about 17% and the solubility of calcium glyoxylate is about 0.7%.

  As a method for producing glyoxylate, a known method can be used. For example, (1) a method based on a neutralization reaction of glyoxylic acid, (2) a salt of glyoxylic acid with an acid dissociation constant larger than glyoxylic acid, And (3) a method by alkaline hydrolysis of glyoxylic acid ester (see, for example, JP-A-2003-300996). In particular, when the alkaline compound used for the neutralization reaction with glyoxylic acid is highly water-soluble, the method of (1) is a salt of an acid whose glyoxylate salt is low in water solubility and has an acid dissociation constant greater than glyoxylic acid. When the water solubility of is high, the method (2) is preferably used.

The method (1) is usually carried out using water as a medium, glyoxylic acid and an alkaline compound, for example, various metal hydroxides or amine compounds are reacted in water, and the precipitated glyoxylate is filtered off. It can be produced by drying.
The method (2) is also generally carried out in water, and glyoxylate can be obtained in the same manner as the method (1). Examples of the acid salt having a larger dissociation constant than glyoxylic acid used in the method (2) include, for example, alkali metal or alkaline earth metal salts of aliphatic carboxylic acids such as sodium acetate, calcium acetate, and calcium propionate. Can be mentioned.

  In addition, after synthesizing glyoxylate, it is possible to carry out the above reaction (1) or (2) in the system without isolating the glyoxylate and use the produced glyoxylate as it is.

  The glyoxylate of the present invention may contain raw materials used in the production of glyoxylate, impurities contained in the raw material, by-products during production, etc., for example, glyoxylic acid, metal hydroxide Products, amine compounds, aliphatic carboxylates, glyoxal, oxalic acid, oxalate, glycolic acid or glycolate may be contained.

  In particular, when glyoxylic acid is used as a raw material, glyoxal, which is a by-product at the time of production thereof, may be contained in the crosslinking agent, and the content of such glyoxal is most desirably 0% by weight. Is preferably 5% by weight or less, particularly 2% by weight or less, and more preferably 1% by weight or less. When the content of glyoxal is large, the stability of the aqueous solution mixed with the AA-PVA resin decreases, the pot life is shortened, and the resulting cross-linked product of the AA-PVA resin discolors over time depending on the storage conditions. There is a case.

  In addition, the glyoxylate in the present invention is acetalized with an alcohol having 3 or less carbon atoms such as methanol and ethanol, a diol having 3 or less carbon atoms such as ethylene glycol and propylene glycol, and hemiacetal. Including the compound. Such an acetal group and a hemiacetal group easily desorb alcohol in water or at a high temperature and take an equilibrium state with the aldehyde group. It functions as.

  Although the compounding quantity of this crosslinking agent (B) is not specifically limited, It is preferable that it is 0.5-20 weight part with respect to 100 weight part of PVA-type resin (A), More preferably, it is 0.8-15 weight part. Parts, particularly preferably 1 to 10 parts by weight. Moreover, it is 0.01-10 mol normally with respect to 1 mol of acetoacetyl groups, Preferably it is 0.1-5 mol, Most preferably, it is 0.5-1 mol. If the amount is too small, the effects of the present invention tend not to be obtained, and if too large, the water resistance tends to decrease, which is not preferable.

[Hydrophilic treatment agent]
The hydrophilization treatment agent of the present invention contains the PVA resin (A) and the crosslinking agent (B), and the blending method of each component is not particularly limited, but the PVA resin ( A method of blending an aqueous solution of a crosslinking agent (B) in an aqueous solution of A), a method of blending a crosslinking agent (B) in an aqueous solution of a PVA resin (A), a crosslinking agent (B in a powdered PVA resin (A) ), A method of applying an aqueous solution of the PVA resin (A), a surface of the aqueous solution of the PVA resin (A), Examples include a method of applying an aqueous solution of the crosslinking agent (B), a method of mixing the PVA resin (A) and the crosslinking agent (B), and dissolving the mixture in water. Preferably, a method of blending an aqueous solution of the crosslinking agent (B) with an aqueous solution of the PVA resin (A) is used.

  The concentration of the hydrophilic treatment agent of the present invention may be appropriately adjusted depending on the desired film heat and coating method, but is usually 1 to 30% by weight, preferably 3 to 20% by weight, particularly preferably. Is 5 to 15% by weight. If the concentration is too low, drying tends to require a large amount of energy (temperature, time). If the concentration is too high, the viscosity becomes too high and the coating workability may be hindered.

  The hydrophilic treatment agent of the present invention includes a rust preventive agent, leveling agent, colloidal silica, plastic pigment and other fillers, colorants, surfactants and antifoaming agents as long as the spirit and film performance of the present invention are not impaired. Antibacterial and antifungal agents may be added.

[Hydrophilic treatment method]
Next, a method for forming a hydrophilic treatment film on an aluminum material, which is a material to be coated, using the hydrophilic treatment agent of the present invention will be described. The hydrophilization treatment method of the present invention is a method of forming a film by coating and drying the hydrophilization treatment agent according to the present invention on part or the entire surface of an untreated or cleaned aluminum-containing metal material. .

  As the material to be coated, an aluminum-containing metal material (aluminum material or aluminum alloy material) used for applications requiring condensation wettability is preferable, and an aluminum alloy heat exchanger is particularly preferable. Such a material to be coated is preferably cleaned in advance with an alkaline or acidic aqueous cleaning agent, but cleaning may be omitted if cleaning is not required. Further, if necessary, the aluminum-containing metal material may be subjected to a rust prevention treatment after the non-treatment or cleaning treatment and before the hydrophilic treatment agent is applied and dried. Examples of the rust prevention treatment include formation of a corrosion-resistant film (chemical conversion treatment film, corrosion-resistant primer layer). In this case, the corrosion-resistant film is not particularly limited, and examples thereof include known chromate, zinc phosphate, titanium-based, zircon-based, organic film-coated base treatment films.

  Next, a hydrophilic treatment agent is applied to the material to be coated by an appropriate coating means so as to obtain a necessary coating amount, and is heated and dried. Examples of the coating means include a roll coating method, a spray method, and a dipping method. Although heat drying is not specifically limited, It is preferable to dry for 5 seconds-120 minutes in the range of 100-220 degreeC, and it is more preferable that it is a temperature range of 120-200 degreeC. When the drying temperature is less than 100 ° C., film formation becomes insufficient, and water resistance and condensation wettability may not be obtained. When the drying temperature exceeds 220 ° C., the reaction between the crosslinking agent and the functional group exhibiting hydrophilicity occurs. Condensation wettability may decrease due to excessive progress. The coating amount of the hydrophilic film obtained by such a method is preferably 0.05 to 5.0 g / m 2, and if it is less than 0.05 g / m 2, the substrate is not sufficiently covered with the hydrophilic film. If it is more than 5.0 g / m 2, there is no problem in the performance which is the gist of the present invention, but it is not economically preferable.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

Example 1
[Production of PVA resin (A1) having oxyalkylene group and acetoacetyl group]
<Manufacture of oxyalkylene group-containing PVA resin>
A polymerization can was charged with 15.0 parts of polyoxyethylene monoallyl ether having an average chain length (n) of oxyethylene group of 10, 85 parts of vinyl acetate, and 10.0 parts of methanol, and the temperature was raised to a reflux state, followed by 30 After refluxing for 5 minutes, 0.08 mol% of azobisisobutyronitrile was added to the total amount of vinyl acetate charged to initiate polymerization. At 2 and 4 hours after the start of the reaction, azobisisobutyronitrile was added in an amount of 0.08 mol% with respect to the total amount of vinyl acetate charged.

  Then, about 8 hours after the start of the polymerization reaction, 20 parts of methanol for cooling and 0.2 part of m-dinitrobenzene as an inhibitor were added, the reaction jacket was cooled to stop the polymerization reaction, and the polyoxyethylene group A vinyl acetate polymer was obtained. The polymerization rate of such a polymer was about 95%.

  Next, after the residual monomer was driven out from the solution of the oxyethylene group-containing vinyl acetate polymer obtained above, it was diluted with methanol and adjusted to a concentration of 40% and charged into a kneader, while keeping the solution temperature at 40 ° C., Saponification was carried out by adding a 2% methanol solution of sodium hydroxide in an amount of 11 mmol to 1 mol unit of vinyl acetate in the copolymer. Saponification progressed as saponification progressed, and finally became particulate. The produced resin was filtered off, washed well with methanol and dried in a hot air dryer to obtain the desired product. The obtained oxyalkylene group-containing polyvinyl alcohol resin had a saponification degree of 99.2 mol%, an average polymerization degree of 750, and an oxyalkylene group content of 2.0 mol%. The product yield was 85%. The yield was calculated from the actual amount of resin obtained relative to the amount of product resin theoretically calculated from the raw material charge.

<Acetoacetylation reaction>
100 parts of the obtained oxyalkylene group-containing PVA resin was charged into a kneader, 20 parts of acetic acid was added to the kneader, and the mixture was swollen and stirred at a rotation speed of 20 rpm. The solution was added dropwise and reacted for another hour. After completion of the reaction, the mixture was washed with 500 parts of methanol three times and dried at 60 ° C. for 10 hours to obtain a PVA resin (A1) having an acetoacetyl group and an oxyethylene group.
The content of the acetoacetyl group of the obtained PVA resin (A1) was 5.0 mol%, and the viscosity of a 4% aqueous solution was 8.0 mPa · s.

<Creation of hydrophilic treatment agent>
To 100 parts by weight of the 10% aqueous solution of the PVA resin (A1) thus obtained, 0.5 part by weight of the crosslinking agent (B) (sodium glyoxylate) (5 parts by weight with respect to the PVA resin (A1)). %) And mixed and stirred to obtain an aqueous resin composition solution. At this time, the molar ratio (X / Y) of the amount of aldehyde groups (X) in the crosslinking agent to the amount of AA groups (Y) in the PVA-based resin (A1) was 0.4.
This aqueous solution is cast on a PET film, left for 48 hours under conditions of 23 ° C. and 50% RH, and then heat-treated at 70 ° C. for 5 minutes to form a water resistance and hydrophilicity evaluation film having a thickness of 100 μm. Obtained.
The water resistance and hydrophilicity of the obtained film were evaluated as follows.

(water resistant)
The obtained film was immersed in water at 23 ° C. for 100 hours, and the elution rate (%) of the film was measured. In calculating the dissolution rate (%), the dry weight (X1) of the film before immersion in hot water and the dry weight (X2) of the film after immersion in hot water (both in g) were obtained and eluted by the following formula The rate (%) was calculated. The results are shown in Table 1.
Elution rate (%) = [(X1-X2) / X1] × 100

(Hydrophilic)
As the hydrophilicity test, the water drop contact angle test was performed according to the following procedure. A PVA resin aqueous solution having a concentration of 10% was applied to a PET film using a 100 μm applicator and dried under the conditions of 120 ° C. × 5 minutes to obtain a PVA film having a thickness of 10 μm. With respect to the obtained PVA film, the water contact angle was measured at 23 ° C. and 50% Rh. The water contact angle is measured by placing a sample horizontally, dropping 2 microliters of pure water on it, and using an automatic contact angle meter (FAMAS: manufactured by Kyowa Interface Science Co., Ltd.) It was measured.

Comparative Example 1
In Example 1, in place of the PVA resin (A1), an acetoacetyl group content of 5 mol%, a polymerization degree of 750, a 4 mass% aqueous solution viscosity of 5.2 mPa · s, and a saponification degree of 99.2 mol% A resin composition aqueous solution was obtained in the same manner as in Example 1 except that a PVA-based resin containing only groups was used, and a resin composition film was prepared in the same manner and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 2
In Example 1, in place of the PVA resin (A1), the oxyethylene group content is 2 mol%, the polymerization degree is 750, the 4 mass% aqueous solution viscosity is 7.6 mPa · s, and the saponification degree is 99.2 mol%. A resin composition aqueous solution was obtained in the same manner as in Example 1 except that a PVA-based resin containing only groups was used, and a resin composition film was prepared in the same manner and evaluated in the same manner. The results are shown in Table 1.

From the above results, in Comparative Example 1 using a PVA resin having only an acetoacetyl group, water resistance was obtained, but the contact angle of water was very large. It was insufficient. In Comparative Example 2 using a PVA resin having only an oxyethylene group, a satisfactory contact angle was obtained, but water resistance was insufficient.
On the other hand, the PVA resin (A) of the present invention has excellent water resistance, a low contact angle, and excellent hydrophilicity.

Example 2
In Example 1, by adding 3 parts of diketene dropwise over 3 hours in the acetoacetylation reaction, an average polymerization degree of 750, a saponification degree of 99.2 mol%, an acetoacetyl group content of 0.59 mol%, oxyethylene An acetoacetyl group- and oxyethylene group-containing PVA resin (A2) having a group content of 2 mol% was prepared. To 100 parts by weight of a 10% aqueous solution of the PVA resin (A2), 0.1 part by weight of a crosslinking agent (B) (sodium glyoxylate) (1% by weight with respect to the PVA resin (A2)) is added and mixed. The mixture was stirred to obtain an aqueous resin composition solution. At this time, the molar ratio (X / Y) of the amount of aldehyde groups (X) in the crosslinking agent to the amount of AA groups (Y) in the PVA-based resin (A2) was 1.1.
This aqueous solution was cast on an aluminum plate (3.0 × 70 × 150 m / m, manufactured by Nippon Test Panel Osaka), left to stand at 23 ° C. and 50% RH for 48 hours, and dried.
The obtained aluminum plate was visually observed and rubbed with a finger to evaluate the adhesion to the aluminum plate.
[Table 2]
Rub with your fingers
Example 2 Uniformity without unevenness No deposit on the finger

Claims (3)

  A hydrophilizing agent containing a PVA resin (A) having an acetoacetyl group and an oxyalkylene group and a crosslinking agent (B).   The hydrophilic treatment agent according to claim 1, wherein the crosslinking agent (B) is glyoxylate.   An aluminum material surface-treated with the hydrophilizing agent according to claim 1 or 2.