JPS61186481A - Hydrophilic corrosion-resisting film-forming material - Google Patents

Abstract

PURPOSE:To enable formation of a film excelling in corrosion resistance and plastic workability by blending each proper amount of sexivalent and trivalent Cr compounds, a fluoride, ion exchange resin powder, and an acrylic acid polymer with a water solvent. CONSTITUTION:The hydrophilic film-forming material is prepared by blending, with a water solvent, a sexivalent Cr compound such as chromium trioxide by 0.05-2g/l expressed in terms of CrO3, a trivalent Cr compound such as chromium sulfate by 1-18g/l expressed in terms of CrO3, a fluoride such as hydrofluoric acid by 0.1-5g/l in the form of F<->, ion exchange resin powder by 1-100g/l as a solid, and an acrylic acid polymer by 1-20g/l as a solid. On application of this to the surface of metallic material, a film hardly causing secular deterioration and having superior corrosion resistance as well as excellent hydrophilic property can be formed. Moreover, as the outer layer of this film is made of resin, workability after film formation can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydrophilic corrosion-resistant film-forming agent capable of forming a film with excellent hydrophilicity, corrosion resistance, and plastic workability on the surface of a metal material.

[Conventional technology and problems]

Metal materials are widely used for various purposes, and depending on the purpose, it is desired that the surface be hydrophilic, meaning that it can be easily wetted by water. That is, in the case of heat exchangers, for example, as performance becomes higher and smaller, attempts are being made to improve heat transfer performance by narrowing the fin spacing.

Therefore, in the heat exchanger, heat exchange is performed with the atmosphere at the fin surface C; moisture in the atmosphere condenses on the fin surface, but the fin spacing is narrowed to, for example, 3 to 4 m or less. In this case, condensed water forms so-called bridges between the fins (20), which increases ventilation resistance and causes noise generation and lowers energy consumption efficiency. Attempts have been made to prevent the formation of bridges.In addition to heat exchangers, C2 is also used when it is desired to prevent dew condensation on metal surfaces in a humid atmosphere, or when it is desired to prevent fogging on metal surfaces that require gloss. Alternatively, when it is desired to increase the wettability of water and increase the amount of water evaporated from the metal surface, a hydrophilic film is formed on two surfaces of the metal surface.

As a means of imparting hydrophilicity, means are taken depending on the metal material used, but a method of applying a treatment agent that imparts hydrophilicity is known.As a coating agent, for example, resin paint C: Hydrophilic Additions of silica powder and surfactants are known as properties imparting agents, but it is necessary to add a large amount of silica powder, which reduces the density of the inorganic film and reduces the corrosion resistance of the film. If the concentration of hexavalent chromium ions is increased to compensate for The agent elutes over time.

There are problems such as deterioration of hydrophilicity, and problems such as increasing hydrophilicity may reduce the corrosion resistance of metal materials depending on the usage environment, and hydrophilicity deteriorates over time. (hereinafter referred to as a film forming agent) is desired.

[Means and effects for solving the problem] The present inventors have conducted repeated research in order to obtain a film-forming agent that can form a film that not only provides good hydrophilicity and corrosion resistance but also has excellent plastic workability. As a result, we have discovered that the object can be achieved by appropriately blending a chromium compound, fluoride, ion exchange resin, and acrylic acid polymer, and have accomplished the present invention. That is, 9 the present invention contains a hexavalent chromium compound in an aqueous solvent of 0.05 to 29/l in terms of Crys, a trivalent chromium compound of 1 to 189/l in terms of Crys, and a fluoride F- of 0. This is a hydrophilic corrosion-resistant film-forming agent containing ion exchange resin powder in a solid content of 1 to 100 t/l and acrylic acid polymer in a solid content of 1 to 209/l.

In the present invention, metal materials include, for example, formed materials such as plates and extruded materials made of aluminum and its alloys, stainless steel, aluminum or zinc-coated steel materials (plated materials, clad materials, etc.), or heat exchange materials. Items with specific shapes such as vessels.

Examples include assembled products.

Examples of the source of the trivalent chromium compound constituting the film forming agent of the present invention include chromium hydroxide.

Inorganic acid salts such as chromium nitrate, chromium fluoride, chromium phosphate, chromium sulfate, organic acid salts such as chromium acetate, chromium maleate, etc. can generally be used as sources of hexavalent chromium compounds. chromates, such as chromium dioxide, ammonium chromate, potassium chromate, sodium chromate, lithium chromate, or ammonium dichromate, potassium dichromate, sodium dichromate, lithium dichromate, etc. Dichromates such as dichromates and the like may be commonly used. In addition to adding trivalent chromium in the form of a compound as described above, a hexavalent chromium compound such as chromium trioxide is used, and a part of this is added to formalin.

It is also possible to mix trivalent compounds by reducing them with an organic reducing agent such as phenol or polyhydric alcohol. It is preferable to use it on the low concentration side.

Therefore, the hexavalent chromium compound seed Crys in the film forming agent
0.05 to 2 in terms of conversion? If the amount added is less than 0.05 g/l, the corrosion resistance effect will not be sufficient, and the crosslinking reaction of the acrylic acid polymer will be sufficiently satisfactory (29 / That's all for now.

Hexavalent chromium is likely to be eluted from the coating, causing pollution problems, and as a result, the corrosion resistance of the C2 coating is reduced.

Trivalent chromium compounds compensate for the decrease in the effectiveness of chromium due to restrictions on the amount of hexavalent chromium compounds used.
It is added in a range of 1 to 18 f/l in terms of ys, and outside this range, the above purpose cannot be fully achieved. Incidentally, if the total amount of chromium exceeds 20 g/l, the metal surface will be colored, the chromium will be locally concentrated, the film will become non-uniform, and it is also economically disadvantageous. However, chromium compounds.

It works in conjunction with fluoride (=acts on the surface of metal materials to form an inorganic layer with high corrosion resistance, and also crosslinks the acrylic acid polymer to make it insolubilized.

Next, as a fluoride, for example, hydrofluoric acid.

Silicon fluoride, boron fluoride, tetanicum fluoride.

Examples include zirconium fluoride and zinc fluoride.

Such soluble fluoride is 0.1-51/l, preferably 0.7-3.
Add in a range of 5t/l. If F- is less than 0.1 g/l, good corrosion resistance of the inorganic layer, which is mainly composed of a reaction product of a metal material and a chromium compound, cannot be obtained, and if F- is more than 59/l.

The elution of the metal material becomes noticeable and the density of the film decreases, making it difficult to control it in the film-forming agent.

Thus, fluoride acts cooperatively with the chromium compound to form an inorganic layer with corrosion resistance and good plastic workability on the metal surface.

next. As an ion exchange resin, it has a hydrophilic atomic group,
It includes compounds that can act as water-insoluble surfactants, and can be appropriately selected from resins commercially available as ion exchange resin particles and ion exchange resin membranes, and has a total ion exchange capacity. is 0.5 [■equivalent/f-
DryR) or more.

More preferably, it is 1 [Misaki equivalent/f-Dry-R] or more. That is, for example, condensation type ion exchange resins such as phenol sulfonic acid type, ethyleneimine-ebichlorohydrin type, and Epoquin type, monopolymer type ion exchange resins such as styrene-divinylbenzene type, andyl-divinylbenzene type, methacryl Acids such as divinylbenzene are available, but these have hydrophilic atomic groups.

Those to which sulfonic acid groups, phosphonic acid groups, phosphinic acid groups, quaternary ammonium, or primary or tertiary amines have been added are commercially available as cation exchange resins or anion exchange resins, and appropriately selected from these. can be used. Furthermore, amphoteric ion exchange resins such as strongly basic anion exchange resins polymerized with acrylic acid, and fluororesins with hydrophilic atomic groups introduced are also commercially available, and any of these can be used. Among these ion exchange resins, cation exchange resins are preferred because they have excellent hydrophilicity, and sulfonic acid type strongly acidic cation exchange resins are most suitable. In addition, the ion exchange resin is not limited to one type, but can be used in appropriate proportions depending on the desired degree of hydrophilicity, such as strong acidic and weakly acidic cation exchange resins or strongly basic and weakly basic anion exchange resins. Two or more types can be used in combination. Furthermore, not only new products but also recycled products that have been used in other processes can be used.

Therefore, the ion exchange resin is used as a powder with a particle size that corresponds to the desired film thickness. For example, when the film thickness is 5 Iin or less, the average particle size IIJ! It is preferable to use particles with a particle size of mJ21 or less. If particles with such a particle size are difficult to obtain, they can be finely ground using a grinder. 1 to 100 F/4, preferably 3 to 60 g/l, and 1 g/l
If it is less than 1, it is difficult to obtain uniform hydrophilicity, and if it is more than 1ooy7, the adhesion and water resistance of the film will decrease due to repeated swelling of the ion exchange resin. .

Therefore, the ion exchange resin acts as a water-insoluble surfactant, and also gives the film hydrophilicity that does not change over time and plastic workability that does not cause die wear when plastic working metal materials. be.

Next, as the acrylic acid polymer, water-soluble or water-dispersible polyacrylic acid or polyacrylic ester (
(hereinafter referred to as resin) is used.

For example, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-methacrylate
Those obtained by polymerization or copolymerization of compounds such as butyl, isobutyl methacrylate, maleic acid, itaconic acid, etc. are used. In addition, for water-soluble resins,
Metal species of divalent or higher valence (chromium ion in the present invention) coexisting in the film forming agent during the relatively low temperature, short time heat treatment process
It is necessary for water-soluble resin to undergo a chelate reaction and become insoluble in water.
It is desirable that the resin has a molecular weight of 0,000 to 300,000, and such resins include Brimar A-1, A-
3, A-5 (trade name, manufactured by Rohm & Hess), etc. are commercially available. 9 for water-dispersed emulsion type resins
The upper limit for molecular weight is not limited to this. Also, the acid value of the resin is 9
Although it should be determined based on the correlation with the molecular weight, it is preferably 5 or more; if it is less than this, high temperature and long-term treatment will be required, which is economically disadvantageous.

Therefore, the amount of resin added is in the range of 1 to 20 f/4 in terms of solid content, preferably 4 to 14 t/l, and 1 t/l.
If the amount is less than 20 g/l or more than 20 g/l, the film tends to become uneven depending on the region, the adhesion and corrosion resistance of the film become non-uniform, and the stability of the film forming agent decreases. Furthermore, when using an emulsion type resin, it is preferable to keep it at 10 f/L or less in view of the stability of the emulsion.

Note that the insolubilization of the water-soluble resin in the present invention is as follows.

As mentioned above, this is due to the formation of poorly soluble organic chromate compounds through a crosslinking reaction with coexisting chromium compounds, and the amount of chromium required for crosslinking can be reduced to zero by adding 0.2% or more of CrQ[). As long as the chromium compound content of the present invention is present, the amount of resin can be substantially 1: arbitrarily changed.

Furthermore, it is also possible to improve the corrosion resistance of the film by adding a thermosetting water-soluble resin.

The film forming agent of the present invention is prepared by blending these compounds in the above-mentioned range, and has a pH of 1.5 to 3.
That's about it. Incidentally, if desired, a surfactant such as α-olefin sulfonate, sodium alkylnaphthalene sulfonate, etc. may be added as an initial hydrophilicity improver.
．． Adding about 5 to 1 g/l causes no problem, and adding 0.1 to 50 g/l of phosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, phosphorous acid, etc. as POi improves the uniform coating of the film. This increases the long-term stability of hydrophilicity, so it can be used depending on the application method.

In addition, silica powder such as silica sol or fumed silica can be added to an amount of 0.5 to 41% as a thickener for the film forming agent, a dispersant for ion exchange resins, or an auxiliary agent for imparting hydrophilicity, or it can be added to ordinary paints. The total amount of additives such as antifungal agents and slip agents is 0.01 to 0.5 t/L.
There is no problem in mixing them to a certain extent.

The method for preparing the film forming agent of the present invention includes, for example,
A bath in which ion exchange resin powder is uniformly dispersed in a resin liquid and a bath B in which a chromium compound and a fluoride are dissolved in a mixture of water and C are separately prepared.

In advance or just before use (method of mixing both baths).

Alternatively, a bath in which ion exchange resin powder is uniformly dispersed in a resin solution and a trivalent chromium solution is added, and a B' bath prepared by mixing fluoride and hexavalent chromium are mixed immediately before use. Method. Alternatively, immediately before use (a method in which all compounds are mixed and used. Furthermore, A, B baths or A,
Any suitable method can be used, such as a method in which the B' bath is applied separately on the surface of the metal material and mixed on the surface of the metal material.

Therefore, the film forming agent of the present invention can be applied by roll coating, for example, in the case of a simple shaped material such as a continuous plate or an extruded material, in the same way as the conventional processing agent.

In the case of a product having a complicated shape, the metal surface C2 can be coated by a suitable method depending on the shape of the metal material, such as brushing, dipping, or spraying. That is, a film-forming agent prepared to have a composition suitable for these application means is applied at a liquid temperature of 20 to 40° C. in a coating amount of 0.
It is coated at a rate of 1 to 5 f/g (dry film standard), and then heat treated at 100 to 250°C for 10 seconds to 30 minutes.
The film is dried and fixed by baking.

Note that if the film forming agent of the present invention is applied while the metal material still has residual heat after rolling, extrusion, or other heat treatment, the film forming agent of the present invention can be applied to cool the metal material, thereby eliminating the subsequent step of heating and fixing the film. You can use the residual heat. or,
Before insolubilizing the film, the film-forming agent of the present invention can be repeatedly applied many times to increase the film thickness. Furthermore, coating can be applied not only after the metal material has been formed, but also because the resulting film has excellent press formability, so it can also be applied after forming the film.For example, it can be applied during press punching, etc. Secondary effects such as reducing die wear may also occur.

The film obtained by applying the film forming agent in this way has a lower layer consisting of an inorganic layer containing a chromium compound and having high corrosion resistance.
It has a two-layer structure, consisting mainly of ion exchange resin and an upper layer consisting of a resin layer that is highly hydrophilic and suppresses the elution of chromium compounds. For this reason, it is believed that far superior hydrophilicity and corrosion resistance are permanently exhibited compared to conventional treatment agents.

〔Effect of the invention〕

The present invention uses a chromium compound, a fluoride, an ion exchange resin, and an acrylic acid polymer as constituent components.

Since a predetermined amount of each of these is blended, when this is applied to the surface of a metal material, a normal coating operation can be performed.
It is possible to form a film with little aging deterioration, excellent hydrophilicity and corrosion resistance, and the formed film has at least a two-layer structure, and the outer layer is a resin layer, so it is easy to process after forming the film. It has excellent effects, such as not causing wear of processing dies or cracking of the film itself, and being able to prevent the elution of hexavalent chromium in the film.

Next, nine embodiments of the present invention will be described.

Example 1 (1) Preparation of hydrophilic corrosion-resistant film forming agent 20% by weight aqueous solution of polyacrylic acid (trade name: Schlimer A)
CIOH (manufactured by Nippon Pure Chemical Industries, Ltd.) with water so that the concentration of polyacrylic acid was 16 f/l (after dilution).

After pulverization, a sulfonic acid polyethylene cation exchange resin (trade name Amberlite IR-120, manufactured by Rohm &]\-S Co., Ltd.) having an average particle size of 1tIm (2!3111m) was added at a ratio of 162/l after being dried. Uniformly dispersed solution (bath) and sulfuric acid/yomu (Crt(SO2)s ・5H
zO) 19.3 f/l, chromium trioxide (Cr(h)
An aqueous solution (bath B) was prepared in advance by mixing 1.5 fμ of hydrofluoric acid (464HF) and 2.1t71 of hydrofluoric acid (464HF), and at the time of use, equal amounts of the bath and bath B were mixed.

(2) Formation of film and press processing As a metal material, after degreasing and cleaning an AA3102 aluminum alloy coil material with a thickness of 0.15111 with a weak alkaline cleaning solution, apply 1 coat of the film forming agent prepared according to the previous item (1) using a roll coating method. .2f/'' (dry film standard) and heat-treated in a hot air drying oven at 150°C for 20 minutes to make the film insoluble and fix it.

Next, using the obtained coil material, a cross fin material for a heat exchanger was manufactured by press punching, press ironing, and C2.

(3) Evaluation test (a) Test method and evaluation of hydrophilicity and corrosion resistance (b) Test method of hydrophilicity (1) Initial performance: After immersing in deionized water, pulling it out for 3
The wetted area ratio was measured after being left for 0 seconds.

(11) Long-term durability: The wetted area ratio was measured after being left in an atmosphere with a relative humidity of 95% and a temperature of 50° C. for 500 hours.

(b) Corrosion resistance test method (1) Salt spray: JISZ 2371 (1955)i
The corrosion area rate after <1000 hours was measured based on the salt spray method according to n.

(11) Acetic acid salt water spray Nialuminum Surface Treatment Technology Research Association Test Standard AR82132 was used to measure the corrosion area rate after <100 hours.

(c) Evaluation The measurement results of the above test are shown in the attached table.

It can be seen that the film treatment agent of the present invention exhibits hydrophilicity equivalent to that of conventional treatment agents, and its corrosion resistance is significantly superior.

(b) Evaluation of press formability The processing die used to process the coil material treated with the film-forming agent of the present invention was used to process the coil material treated with the film-forming agent of the present invention. It was confirmed that the product could be used without any trouble even when the throughput was reached, and that a film with less die wear was obtained.This was also proven in the pressure ball wear test.

Example 2 (1) Preparation of hydrophilic corrosion-resistant film forming agent
0) to 1.92 t/l.

Chromium dioxide (Crys) is converted to 1.42F/4fluoric acid (4
1 t/l of orthophosphoric acid (100 tHsPO)
4) mixed at a ratio of 1 f/l (bath) and a 25% by weight aqueous solution of acrylic acid polymer (trade name Brymer A-1, manufactured by Rohm & Co., Ltd.) diluted with water. After setting the acrylic acid polymer concentration to 15.4Vt.

The solid content of sulfonic acid type ion exchange resin (trade name R-120B, manufactured by Organo) with an average particle size of 05 to IA1m is 5.
A homogeneous (bidispersed aqueous solution (bath B)) is prepared in advance by mixing to give a ratio of 0 f/l.

They were prepared by mixing equal amounts of each before use.

(2) Film formation and press processing A with a thickness of 012 mm treated with trichlene degreasing as a metal material
The coating was applied to an aluminum plate made of A1050 alloy using a roll coater in the same manner as in Example 1, and the coating was made insoluble and fixed in the same manner to form a coating with a thickness of IAlrrl. Then, press working was performed in the same manner as in Example 1. (3) Evaluation test The same test method as in Example 1 was conducted. These results are shown in the table below, and the corrosion resistance is significantly superior to that of conventional treatment agents.

Regarding the plastic workability, there was no trouble even when the throughput was 10 times higher than that of the conventional method.

Comparative Example: Commercially available acrylic resin paint (product name Water Silua 27)
．． (manufactured by Dainippon Ink Co., Ltd.), melamine resin paint (trade name: Watersol 8695; manufactured by Dainippon Ink Co., Ltd.), and colloidal silica (trade name: Snowtex).

(manufactured by Nissan Chemical Co., Ltd.) and 48 parts each in terms of solid content.

A mixture of 12 parts and 40 parts was prepared, and the same tests were conducted by applying, fixing by baking, and pressing under the same conditions as in the example. The results are shown in the attached table.

Claims (1)

[Claims] 1) In an aqueous solvent, add a hexavalent chromium compound to 0.05 to 2 g/l in terms of CrO_3, and a trivalent chromium compound to CrO_3.
1 to 18 g/l in terms of fluoride, 0.3 as F^-.
1-5g/l, solid content of ion exchange resin powder 1-10
0g/l, acrylic acid polymer solid content 1-20g/l
1. A hydrophilic corrosion-resistant film-forming agent characterized by comprising: l.