JP2682168B2 - Metal anticorrosion composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the Invention "Field of Industrial Application" The present invention relates to a metal rust preventive composition, and more particularly, it has good storage stability at room temperature for a long period of time. The present invention relates to a metal rust preventive composition which forms an effective film by coating water on a metal surface and presents an effective film by the presence of water in the atmosphere or slight heating. The product is a rust preventive composition particularly suitable for zinc and zinc alloy plating such as zinc plating, nickel / zinc plating, iron / zinc plating, tin / zinc plating, etc., and a metal whose surface is chromated. It can be widely used in various industrial fields using metals, such as the machine industry, electrical equipment industry, and automobile industry.

"Prior Art" Conventionally, many treating agents and paints have been used for the purpose of protecting the metal surface from various corrosive environments. Among them, a coating material that forms a film and cures at room temperature or with slight heating has been widely praised from the viewpoint of thermal energy because it saves resources and simplifies the process. Examples of such paints include, for example, two-component paints such as polyurethane-based and epoxy-based paints, air-drying paints such as alkyd-based and polybutadiene-based paints, and moisture-curable paints such as silicone-based and various modified silicone-based paints. To be

"Problems to be Solved by the Invention" However, coating materials that can be formed into a film or cured at room temperature or with slight heating have the following problems.

In other words, the two-component curing type coating forms a dense coating film and has excellent rust prevention properties, but there are restrictions on work such as the complexity of weighing and mixing when mixing the curing agent and the short working life. Air-drying type paints often form coating films with excellent water resistance, but residual unsaturated bonds may reduce the antioxidant properties and weather resistance of coating films. In addition, silicone-based moisture-curable coatings having excellent weather resistance and heat resistance have problems in storage stability and coating film rust resistance.

As a solution to those problems, the present inventors have previously shown that in Japanese Patent Application No. 57-203358 a film thickness much thinner than a normal coating film, it exhibits excellent rust-preventing properties, and at room temperature. Although a curable metal rust preventive composition has been proposed, the composition is colored with various pigments for the purpose of imparting an aesthetic appearance,
When a rust preventive agent, a rust preventive pigment, etc. is added to further improve the rust preventive property, or a lubricating substance etc. is added for the purpose of improving the surface characteristics of the coating film, the active groups on the particle surface of the pigment etc. There is a problem in that the stability of the composition may be impaired by the reaction between the adsorbed moisture on the particle surface and the like and the constituent components in the composition.

The present inventors have made various studies with the aim of solving the problem.

(B) Structure of the Invention "Means for Solving the Problem" As a result of the study by the present inventors, an organosilicon compound having an aminoalkyl group and an alkoxysilyl group as previously proposed (hereinafter referred to as "organosilicon compound") In a metal rust-preventing composition containing, as a main component, an epoxy resin having two or more hydroxyl groups in one molecule (hereinafter referred to as “epoxy resin”), a decrease in stability caused by pigment blending is caused by a specific solvent. That is, the inventors have found that it can be prevented by using a monoalkyl ether of a dihydric alcohol as a solvent, and completed the present invention.

That is, the present invention provides an organosilicon compound having an aminoalkyl group and an alkoxysilyl group, an epoxy resin having two or more hydroxyl groups in one molecule, a pigment, and a monoalkyl ether of a dihydric alcohol. The present invention relates to a rust composition.

Organosilicon compound The organosilicon compound used in the present invention has both an aminoalkyl group and an alkoxysilyl group, and includes those widely known as silane coupling agents. The specific compound is one aminoalkyl group such as aminomethyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminoisobutyltrimethoxysilane and 3 groups. Aminoalkyltrialkoxysilane having an alkoxysilyl group of N- (β
-Aminoethyl) aminomethyltrimethoxysilane, N
N- (β having an N- (aminoalkyl) aminoalkyl group and three alkoxysilyl groups such as-(β-aminoethyl) aminomethyltriethoxysilane and N- (β-aminoethyl) aminopropyltrimethoxysilane -Aminoalkyl) aminoalkyltrialkoxysilane; aminoalkyldialkoxysilane having one aminoalkyl group and two alkoxysilyl groups such as aminomethyldiethoxysilane and γ-aminopropylmethyldiethoxysilane; N- Examples include N- (β-aminoalkyl) aminoalkylalkyldialkoxysilanes having an N- (aminoalkyl) aminoalkyl group such as (β-aminoethyl) aminopropylmethyldimethoxysilane and two alkoxysilyl groups, Have two or more alkoxysilyl groups The is preferred in order to increase the corrosion resistance.

Epoxy resin The epoxy resin having two or more hydroxyl groups in one molecule used in the present invention has also been described in detail in the above proposal, and bisphenol A based on bisphenol A is preferred as the epoxy resin for the present invention. And F-type epoxy resins, those having various characteristics are commercially available, and examples thereof include Epicoat 1001, 1004, 1007 and 1009 (all made of oiled shell epoxy). Used in the present invention. Other examples include brominated epoxy resins in which some of the hydrogen atoms of the benzene ring of bisphenol A type epoxy resin have been replaced with bromine, such as Epicoat 1045, Epicoat YL903 (all made by Yuka Shell Epoxy), and dimer acid-based resins. Glycidyl ester type epoxy resin, for example, Epicoat 871 (made by Yuka Shell Epoxy), phenoxy resin, for example, PKHH
(Made by Union Carbide Corporation) and the like.

The above epoxy resin may be used in combination with other resins or compounds within a range that does not impair the performance of the composition of the present invention. For example, glycidyl amine type epoxy resin, novolac type epoxy resin, glycidyl ester type epoxy resin, etc. A resin having an oxirane ring other than: {β-
Organosilicon compounds such as (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane; polyvinyl butyral resin, polyvinyl formal resin, polyester resin,
Resins having a hydroxyl group in the molecule such as cellulose acetate butyrate and ethyl cellulose can be used together. Among them, the resin having a hydroxyl group in the molecule is particularly useful because it reacts with the alkoxysilyl group of the organosilicon compound to form a tough coating film.

○ Monoalkyl ether of dihydric alcohol The monoalkyl ether of dihydric alcohol used as a solvent in the present invention has two alcoholic hydroxyl groups in one molecule, and one of the hydroxyl groups is an alkyl ether. Specifically, for example, ethylene glycol alkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether; propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono. Propylene glycol monoalkyl ethers such as butyl ether; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobub Diethylene glycol monoalkyl ethers such as chill ether; Dipropylene glycol monomethyl ethers such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether; Others, 3-methoxybutyl alcohol, 3-methyl-3 -Methoxybutyl alcohol and the like.

In the present invention, as the monoalkyl ether of the dihydric alcohol, various ones as described above are used, but ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether having good dissolving power are preferable for the present invention, and particularly, , The boiling point at atmospheric pressure is 100
Monomethyl, monoethyl ether and the like having a temperature of not less than 220 ° C and not more than 220 ° C are preferable because they have an appropriate volatilization rate and good drying property.

Dihydric alcohols and monohydric alcohols that have not been monoalkyl etherized have problems such as poor solubility and gelation in a short time even when dissolved. It cannot be used as a substitute. Further, dihydric or polyhydric alcohols in which all of the hydroxyl groups are alkyl etherified are inferior in the dispersion stability of the pigment, and there is a problem that they settle out during storage and cannot be similarly substituted.

In the present invention, the monoalkyl ether of a dihydric alcohol may be used in combination with one or more of other solvents, for example, an aromatic solvent such as toluene, xylene, mesitylene; acetone, methyl ethyl ketone, Monoketone solvents such as methyl isobutyl ketone, cyclohexanone, and isophorone; 1,3-diketone solvents such as acetylacetone, methyl acetoacetate, ethyl acetoacetate and β-ketocarboxylic acid ester solvents; such as ethyl alcohol, propyl alcohol, butyl alcohol, etc. Alcohol-based solvent; examples thereof include ester-based solvents such as ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate, which can be used in combination.

These solvents are used in combination with a monoalkyl ether of a dihydric alcohol within a range that does not impair the storage stability of the composition of the present invention or the drying property at the time of coating. 10% by weight in all solvents
It is preferably used in combination as described above, and particularly preferably 30% by weight or more. If the amount of monoalkyl ether of dihydric alcohol is less than 10% by weight, the composition stability of the composition containing the pigment may be increased, or the storage stability of the pigment may be significantly reduced. May occur.

When a dicarbonyl compound such as a 1,3-diketone-based solvent or a β-ketocarboxylic acid ester-based solvent is used in combination with the solvent, the imine reacts with the aminoalkyl group of the organosilicon compound in the composition of the present invention. An epoxy resin that forms a compound and stably exists with an epoxy resin having an oxirane ring during storage, and once applied to a base material, the organosilicon compound is regenerated by moisture in the atmosphere and the like, and an epoxy resin having an oxirane ring. Since it has the property of reacting with and forming a coating film, it is effective for increasing the stability of the composition of the present invention, and therefore it is a preferable compound to be used in combination. Because of the characteristics like
It is preferably 5 to 20% by weight in the total solvent.

○ Pigment As the pigment to be used in the present invention, any pigment widely used in the field may be applied, but for the present invention, a pigment having a primary particle diameter of 10 μm or less is preferable, and specifically, carbon is used. Black pigments such as black, acetylene black, lamb black, bone black and black iron oxide; white pigments such as titanium oxide, zinc white, and lead white; anticorrosion pigments such as zinc chromate and strontium chromate; calcium carbonate, talc , Clay, kaolin, alumina,
Examples thereof include extender pigments such as silicic acid anhydride; metal powders such as zinc powder and aluminum powder; and molybdenum disulfide, ethylene tetrafluoride powder, vinylidene fluoride powder and the like.

In the present invention, various pigments as described above are used, but carbon black that imparts a black appearance, aluminum powder or chromate or fine particulate silicic acid anhydride that improves rust resistance, storage stability and It is preferable because it exerts a remarkable effect on coating film performance.

For more information on carbon black, see Encyclopedia of Chemical Technology (Encylopedia
of Chemical Technology (Second Edition (Vol.4 p.24
3-282), it is classified into channel black, furnace black, thermal black and the like, and in the composition of the present invention, furnace black is preferable from the viewpoint of coloring degree and dispersion stability.

The aluminum powder is produced by crushing aluminum foil, spraying molten aluminum, or the like, and from the viewpoint of safety in handling, aluminum paste in the form of an aluminum paste kneaded with a solvent or oil can be preferably used.

Zinc chromate is produced by the reaction between chromic anhydride and potassium dichromate or zinc white, and strontium chromate is produced by the reaction between strontium sulfate and sodium dichromate.

Particulate silicic acid anhydride is called fumed silica and hydrophobic silica (hydrophobic silica) obtained by treating fumed silica with silane or polysiloxane, and is known as Encyclopedia of Chemical Technology. (S
econd Edition) Vol.18 p.61-72) for details.

○ Blending ratio The blending ratio of the composition of the present invention is preferably such that the weight ratio of the organosilicon compound to the epoxy resin is 90/10 to 5/95, and more preferably 60/40 to 10/90. is there. If the ratio is out of this range, the film-forming property may be deteriorated or the curing speed may be slowed during coating on the object to be coated, which may impair the durability of the coating film such as rust-preventive property.

The weight ratio of the pigment is preferably 1/100 to 200/100, and more preferably 5/100 to 150/100 with respect to the total amount of the organosilicon compound and the epoxy resin.
If the ratio is out of this range, the effect of blending the pigment may not be obtained, or the strength of the coating film may be significantly reduced, which is not preferable.

Further, the concentration of the nonvolatile content in the solution is preferably 10 to 90.
The solvent is used in an amount of 10% by weight, more preferably 10 to 60% by weight. If the ratio is out of this range, the liquid viscosity at the time of coating becomes unsuitable and the coating film after coating may be defective.

Preparation Method The composition of the present invention is prepared by dissolving an organosilicon compound and an epoxy resin in a solvent containing a monoalkyl ether of a dihydric alcohol or a monoalkyl ether of a dihydric alcohol at room temperature or under heating, and then adding a pigment. It is easily manufactured by mixing and dispersing. Alternatively, a part or all of the organosilicon compound or a part of the epoxy resin may be dispersed in the pigment and then added to produce.

As a method for mixing / dispersing the pigment, a method known in the art may be applied, for example, a stirrer such as a paddle type mixer, a turbine type mixer, an impeller type mixer or a mill disperser such as a sand mill, a ball mill, an attritor or a roll mill. It is possible to mix and disperse by appropriately selecting and combining.

Further, various additives such as a viscosity modifier, a defoaming agent, a siloxane bond condensation catalyst, an antioxidant and an ultraviolet absorber may be added at an appropriate stage during production.

-Applied substrate The composition of the present invention can be widely applied to metal substrates, but iron and iron alloys, aluminum and aluminum alloys, copper and copper alloys, zinc plating and zinc alloy plating, nickel plating, chrome plating, It is prized for various plating such as cadmium plating, especially galvanized by electroplating, hot dipping, mechanical plating, etc., nickel / zinc plating, iron / zinc plating, tin / It exhibits excellent anti-corrosion performance against zinc and zinc alloy plating such as zinc plating, and on metals whose surfaces are colored, black, green and colorless chromate treatments.

O Application Method Since the composition of the present invention is in the form of a solution, it can be easily applied to a metal base, and as a method thereof, known coating methods such as spray coating, dip coating, roll coating and brush coating can be applied. By removing the solvent at room temperature or under heating conditions after coating, a uniform coating film is formed and the object of the present invention can be achieved. The film thickness is 1 to 300 μm,
It is preferably from 1 to 100 μm, more preferably from 1 to 20 μm, and it is a major feature of the composition of the present invention that remarkably rust-preventing property can be imparted by a film thickness of 10 μm or less.

"Action" The present invention is to improve the dispersion stability of the composition previously proposed by the present inventors at the time of compounding the pigment, and when compounding the pigment, a monoalkyl ether of a dihydric alcohol is used as a part of the solvent. Alternatively, it is achieved by using it as a whole, and the pigment dispersion stability and liquid viscosity stability of the composition are improved, the long-term storage stability is excellent, and the composition is applied to the surface of the applied substrate. When it is worked, it has the effect of forming a good coating film and significantly improving the coating film performance such as rust prevention.

The reason why the composition of the present invention exhibits excellent liquid storage stability is not clear, but the following reasons are presumed.

The hydroxyl groups of the monoalkyl ether of dihydric alcohol cover the active groups (OH group, COOH group, etc.) on the surface of the pigment, and suppress the reaction or hydrogen bond with the alkoxyxylyl group of the organosilicon compound, while the alkyl ether group The part improves the wettability with the organic resin part.

The hydroxyl group of the monoalkyl ether of the dihydric alcohol causes transesterification with the alkoxysilyl group of the organosilicon compound, causing hydrolysis of the organosilicon compound and condensation of the organosilicon compounds due to the water present in the liquid or the water adsorbed on the pigment surface. Suppress.

The hydroxyl group of the monoalkyl ether of the dihydric alcohol forms a hydrogen bond with the aminoalkyl group of the organosilicon compound and suppresses the reaction between the aminoalkyl group and the oxirane ring of the epoxy resin.

The reason why the bisphenol A type epoxy resin having two or more hydroxyl groups in one molecule in the present invention is preferable is that the aminoalkyl group of the organosilicon compound and the oxysilane ring of the epoxy resin react very easily.
When the number of hydroxyl groups in the molecule is less than two, the reaction rate is slow and it takes a long time to form a coating film, whereas when it has two or more hydroxyl groups, a strong coating film is formed in a short time. It is considered that this is because the hydroxyl groups of the epoxy resin greatly contribute to the reaction with the organosilicon compound.

"Examples and Comparative Examples" Examples 1 to 6 Epoxy resin (Epicoat 1004: made by Yuka Shell Epoxy) 66.4 parts by weight (hereinafter referred to as "part"), ethylene glycol monoethyl ether 91.8 parts, toluene 91.8 parts and methyl ethyl ketone 91.8 parts 7.2 parts of carbon black (# 1000 manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) was stirred and mixed with a liquid dissolved in a mixed solvent consisting of, and dispersed by a ball mill type disperser to obtain a black dispersion liquid. Γ-aminopropyltriethoxysilane 4
4.2 parts were added and mixed to obtain a composition. (Example 1) In the same manner, the solvent of Example 1 was mixed with 110.0 parts of propylene glycol monomethyl ether and 54.9 of acetylacetone.
Parts and xylene 110.0 parts to obtain a composition. (Example 2) In the same manner, the solvent of Example 1 was mixed with 110.0 parts of 3-methyl-3-methoxybutyl alcohol and 11 cyclohexanone.
A composition was obtained in place of 0.0 parts and xylene 54.9 parts. (Example 3) By the same method, 7.2 parts of carbon black as the pigment of Example 1 and 38 parts of the same pigment zinc chromate (ZTO manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) were blended together to obtain a composition.
(Example 4) In the same manner, 7.2 parts of carbon black as the pigment of Example 1 was used together with 2.0 parts of fumed silica (Aerosil R972: manufactured by Nippon Aerosil Co., Ltd.), which was also a pigment, to obtain a composition. (Example 5) By the same method, instead of the pigment carbon black of Example 1, an aluminum paste (Toyo Aluminum 0100) was used.
A composition was obtained using 30.3 parts (NA: non-volatile content 66% by weight). Example 6 These solution-like compositions were subjected to the following tests.

(1) Liquid state Each solution of 400 cc was put in a tin oil can, immersed in a water tank at 40 ° C. and left for 1 month, and then changes in the properties of the solution were observed.

(2) Salt spray test Zinc-plated yellow chromate treatment test plate (70 x 150 x 0.8) dip-coated in each solution is heated and dried at 80 ° C for 10 minutes, and then salt spray test (JIS-Z-2371) 600Hr is applied. I served.

 Table 1 shows the test results.

Example 7 A resin composed of 44.2 parts of an epoxy resin (Epicoat 1004: made by Yuka Shell Epoxy) and 22.2 parts of a polyvinyl butyral resin (Eslek BL1 made by Sekisui Chemical Co., Ltd.) was used as a mixture of 184.6 parts of propylene glycol monomethyl ether, 45.7 parts of xylene and 45.7 parts of methyl isobutyl ketone. Further dissolved in a mixed solvent consisting of and carbon black (# 100 manufactured by Mitsubishi Kasei
7.2 parts of (0) was mixed by stirring and dispersed by a sand mill type disperser to obtain a black dispersion liquid. 44.2 parts of γ-aminopropyltriethoxysilane was added to and mixed with this to obtain a composition. This composition was evaluated by the above test method. The results are also shown in Table 1.

Comparative Examples 1 to 5 In the same manner as in Example 1, the mixed solvent of Example 1 was mixed with 8.9 parts of ethylene glycol monoethyl ether and 13 parts of toluene.
A composition was obtained in place of 3.0 parts and 133.0 parts of methyl ethyl ketone. Comparative Example 1 A composition was obtained in the same manner as in Example 1 except that 91.8 parts of ethylene glycol, 91.8 parts of toluene and 91.8 parts of methyl ethyl ketone were used as the mixed solvent of Example 1. (Comparative Example 2) In the same manner as in Example 1, the mixed solvent of Example 1 was mixed with 91.8 parts of ethylene glycol diethyl ether and 91.8 of toluene.
Parts and 91.8 parts of methyl ethyl ketone to obtain a composition. Comparative Example 3 In the same manner as in Example 1, the mixed solvent of Example 1 was added with n-
A composition was obtained by replacing 91.8 parts of butanol, 91.8 parts of toluene and 91.8 parts of methyl ethyl ketone. (Comparative Example 4) In the same manner, the mixed solvent of Example 1 was replaced with 8.9 parts of ethylene glycol monoethyl ether, 133.0 parts of toluene and 133.0 parts of methyl ethyl ketone, and zinc chromate (7.2 parts with carbon black). A composition was obtained by combining 3.8 parts of Japan Inorganic Chemical Industry ZTO) together.
(Comparative Example 5) These compositions were evaluated by the same test method as in the Examples. The test results are shown in Table 2.

(C) Effect of the invention The metal substrate immersed in the composition of the present invention is formed into a coating film by simply air-drying, and very easily imparted with good rust prevention property. Even with a thin film thickness of 1 to 10 μm, it shows good rust resistance and excellent aesthetics, and does not cause various problems in work and process due to the increase in the thickness of the base material due to the coating film. Further, since the composition of the present invention is excellent in storage stability and can always exhibit stable coating film performance, it can be applied to chromate-treated materials such as zinc plating and zinc alloy plating which are widely used in industry. The present invention can provide an extremely simple rust preventive method, which greatly contributes to each industry.

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Claims (1)

(57) [Claims] 1. A metal rust preventive comprising an organosilicon compound having an aminoalkyl group and an alkoxysilyl group, an epoxy resin having two or more hydroxyl groups in one molecule, a pigment and a monoalkyl ether of a dihydric alcohol. Composition.