JP6592648B2 - Anti-rust paint - Google Patents

Description

  The present invention relates to a thin film-type anticorrosive paint that does not contain harmful metals such as chromium, and more specifically, it has a high antirust function even if it is a thin film that can be applied to, for example, precision equipment and steel plates for press forming of automobiles. The present invention relates to a paint capable of forming a colored coating film.

  In the field of coatings intended for rust prevention of steel, rust-proof coatings mainly composed of zinc powder and chromic acid have been frequently used. This paint can keep the zinc powder stable for a long time by the passivating action of hexavalent chromium, and is excellent in storage stability of the liquid. Moreover, the coating film which consists of a coating material containing this zinc powder is effective in the sacrificial anti-corrosion action by well-known zinc, and prevents the corrosion of the base steel, Therefore The outstanding rust prevention effect is acquired.

  However, in recent years, environmental pollution due to the toxicity of hexavalent chromium and health damage to the human body have become a concern, and the movement to legally restrict the use of harmful metals such as hexavalent chromium has been accelerated. In response to this trend, companies that manufacture consumer products such as precision equipment and automobiles are proceeding with a study in which no harmful metals such as hexavalent chromium are used. Therefore, in the field of anticorrosive paints, paints that do not contain toxic metals such as chromium are strongly desired.

  As an example of such a rust-free paint containing no chromium, there is a kind of paint in which zinc powder and a binder component are dispersed or dissolved in an organic solvent, that is, zinc rich paint. This zinc-rich paint has an organic type and an inorganic type, and from the viewpoint of durability, an inorganic type using an organosilicon compound as a vehicle is superior. For example, it is used as a primer in heavy-duty anticorrosive coating on ships and bridges. It has been.

  However, inorganic zinc rich paints tend to generate voids in the film, and it is difficult to control the thickness of the coating film. In order to overcome such drawbacks, the following techniques are disclosed.

  Patent Document 1 discloses a technique of additionally containing whisker-like calcium carbonate having a major axis of 20 to 30 μm. In this technique, the added whisker has a function of preventing the occurrence of cracks in the coating.

  Patent Document 2 discloses a zinc rich paint in which an alkyl silicate resin having a weight average molecular weight / number average molecular weight ratio of 40 or less is used, and the morpholine gel time of the paint is 60 seconds or less. It is described that such a coating has a fast curing time, and therefore suppresses a phenomenon in which cracks develop and lead to voids.

  Although such a technique is certainly effective as a thick film zinc rich paint, it is possible to stably form a thin film of about 10 μm and to provide a paint having a high anticorrosive property. Not done.

  The main applications of such a thin film with high anticorrosion properties are office equipment, electrical equipment, automobiles, etc. Specifically, fastening parts such as bolts and nuts, fasteners such as clamps and clips, plates And press-molded products such as housings, hinges and panels. These members are often subjected to a strong shearing force at the time of processing or assembling, although the assembling accuracy is severe, and a high level is required for the strength and adhesion of the coating itself.

  One effective means for meeting this requirement is baking of the coating film at a high temperature. However, when the zinc rich paint according to the prior art is baked at a high temperature of about 300 ° C., the organosilicon compound serving as the binder rapidly shrinks, and even if the technique according to the patent literature as described above is used, Crack growth cannot be stopped, and breakage may even occur in the steel material of the substrate.

  Therefore, it is an important technical problem to provide a rust preventive paint that can form a thin film that does not easily generate cracks even when a baking process is performed at a high temperature without using any harmful metal compound such as chromium. In this regard, the present applicant has proposed a rust-preventing paint that includes a non-aqueous binder and a metal powder, and uses a solution containing an organosilicon compound and an organic titanate compound as the non-aqueous binder (Patent Document). 3). This rust preventive paint not only has high corrosion resistance but also has an advantageous effect that the pot life is long.

By using the above rust preventive paint proposed by the present applicant, high corrosion resistance can be imparted. When coloring a member to which corrosion resistance is imparted, a coloring paint may be further applied on the coating film of the anticorrosive paint. However, there is a problem in that the processing cost increases due to an increase in the coloring process for applying a coloring paint for coloring separately from the rust preventive paint. Further, the coloring paint applied on the coating film of the anticorrosive paint may affect the sacrificial anticorrosive action of zinc in the paint film, which may reduce the antirust property.
JP 11-293200 A JP 2004-359800 A Japanese Patent No. 4111531

  An object of the present invention is to provide a rust-preventing paint capable of forming a colored paint film with good color development, which does not require coloring with another paint for coloring on the paint film of the anti-rust paint.

In order to achieve the above object, the present inventor has formulated a paint that vividly develops color while maintaining good rust prevention properties by blending a color pigment into a rust preventive coating and blending colored aluminum powder. The knowledge that a film can be formed was obtained.
The present invention has been completed based on the above findings, and includes the following matters.

(1) 5 to 40% by mass of organosilicon compound, 0.05 to 2% by mass of organic titanate compound, 5 to 60% by mass of metal powder comprising zinc powder and colored aluminum powder, and organic solvent based on the total paint 10 to 60% by mass and a coloring pigment , the zinc powder is not colored, and its content is 3 to 9% by mass based on the total paint. paint.
(2) The rust preventive paint according to (1), wherein the organosilicon compound is one or more compounds selected from the group consisting of tetraalkylsilicate compounds having an alkyl group having 3 or less carbon atoms and oligomers thereof.
(3) The organic titanate compound is an organic compound represented by the general formula Ti (X) ₄ and an oligomer thereof, wherein X is carbon of methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, and tert-butoxy One or more functional groups selected from the group consisting of an alkoxy group having a number of 4 or less, lactate, triethanolaminate, acetylacetonate, acetoacetate, and ethylacetoacetate, and a hydroxyl group ( The anticorrosion paint according to 1) or (2).
(4) The rust preventive paint according to any one of (1) to (3), wherein the metal powder is scaly.

Since the rust preventive paint of the present invention does not contain a harmful metal compound such as chromium, there is no need to worry about environmental pollution or health damage to the human body.
By blending the colored aluminum powder together with the color pigment, it is possible to form a vivid color coating film while maintaining good rust prevention. For this reason, since a vivid color can be given to an application object only with a rust preventive paint, a coloring process of applying a color paint on the coating film of the rust preventive paint becomes unnecessary.
Moreover, it is possible to form a thin film having a surface property of about 10 μm, and even if this thin film is baked at a high temperature, no cracks are generated in the film. Therefore, it is possible to form a rust preventive film having excellent corrosion resistance while being a thin film.

The rust preventive paint according to the present invention includes an organic silicon compound, an organic titanate compound, a metal powder composed of zinc powder and a colored aluminum powder, and an organic solvent as essential components, and a small amount of additives as necessary. .
Hereinafter, these components will be described in detail. In the following description,% is mass% based on all paints unless otherwise specified.

(Organic silicon compound)
As a binder component in the rust preventive paint of the present invention, an organic silicon compound and an organic titanate compound are used so that cracks do not occur even when baking is performed at a high temperature.

Of these, the organosilicon compound is one or more selected from alkoxysilanes and hydrolysates thereof. The alkoxysilane is preferably a compound represented by the general formula (X ′) Si (X ″) ₃ .

  Here, X ′ is a hydroxy group, a lower alkoxy group such as methoxy, ethoxy or isopropoxy, a lower alkyl group such as methyl or ethyl, a lower alkenyl group such as a vinyl group, or γ-glycidoxypropyl. , Γ-methacryloxypropyl, γ-mercaptopropyl, and the like. X ″ is selected from a hydroxy group and an alkoxy group such as methoxy, ethoxy, isopropoxy, etc., and three X ″ may be the same or different.

  Specific examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and the like. But it is not limited to that. Various alkoxysilanes that are commercially available as silane coupling agents may be used.

  Among these alkoxysilanes, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane or oligomers thereof are preferable, and tetraalkoxysilanes having 3 or less carbon atoms or oligomers thereof are particularly preferable. When a condensation reaction is caused by the baking treatment, a film having a three-dimensional crosslinked structure can be formed, and the film strength is easily improved. Further, since the volume shrinkage during condensation is relatively small, cracks are difficult to grow.

  The amount of the organosilicon compound is desirably 5 to 40% of the total paint. If the amount is less than 5%, the coating strength tends to be low, and if the addition amount is further small, a clear void (void) is generated between the metal powders so that the rust prevention function is also lowered. become. On the other hand, when added in excess of 40%, the dispersion concentration of the metal powder in the film is relatively lowered, so that the rust prevention function tends to be lowered. Moreover, since the overlapping area of the metal powder to be laminated is reduced, there is a possibility that the function of suppressing the progress of cracks is lowered. A more preferable range is 10 to 35%, and a particularly preferable range is 15 to 35%.

(Organic titanate compound)
In the present invention, an organic titanate compound is added to the medium in order to improve the film properties. The organic titanate compound means an organic compound represented by Ti (X) ₄ as a general formula and an oligomer thereof. Here, X is selected from a hydroxyl group, a lower alkoxy group, and a chelating substituent, and the four Xs may be the same or different.

  The lower alkoxy group means an alkoxy group having 6 or less carbon atoms, preferably 4 or less, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy and the like.

  The chelating substituent means a group derived from an organic compound having chelating ability. Examples of such organic compounds include β-diketones such as acetylacetone, alkylcarbonylcarboxylic acids such as acetoacetic acid and esters thereof, hydroxy acids such as lactic acid, alkanolamines such as triethanolamine, and the like. Specific examples of the chelating substituent include lactate, ammonium lactate, triethanolamate, acetylacetonate, acetoacetate, ethylacetoacetate, and the like.

  This organic titanate compound exhibits a high function with a small amount of addition as described later. That is, when subjected to baking treatment at a high temperature, the added organic titanate compound functions as a curing agent or a catalyst, and promotes a three-dimensional crosslinking reaction of the organosilicon compound. For this reason, the hardening rate of a binder component increases and the progress of a crack is suppressed.

  Further, the chemical bond between the organosilicon compound and the metal powder and the chemical bond between the organosilicon compound and the steel material as the base material are also promoted by the presence of the organotitanate compound, and the bond strength is increased. For this reason, the interfacial peeling between the metal powder and the binder and the interfacial peeling between the steel material and the binder are suppressed, and the progress of cracks is suppressed.

  The addition amount of the organic titanate compound is preferably 0.05 to 5.0%. If the amount of the organic titanate compound is too small, the effect cannot be obtained and cracks are likely to occur, and the rust prevention characteristics of the film may be lowered. On the other hand, when it becomes excessive, it tends to be hydrolyzed by absorbing humidity in the atmosphere, and the pot life tends to be shortened. A more preferable range is 0.05 to 2%, and a particularly preferable range is 0.1 to 2%.

(Metal powder)
As the metal powder, zinc powder and aluminum powder, which are conventionally used for zinc-rich anticorrosive paints, are used. In the present invention, the zinc powder means a metal powder containing zinc as a component, and also includes a zinc alloy powder. The colored aluminum powder signifies that the surface of a metal powder containing aluminum as a component is provided with a colored pigment. Here, the metal powder containing aluminum as a component contains an aluminum powder and an aluminum alloy powder as well as the zinc powder. Accordingly, the colored aluminum powder includes a colored aluminum alloy powder. Examples of the zinc alloy include Zn—Ni, Zn—Sn, Zn—Fe, Zn—Al, Zn—Al—Mg, and the like.

  By adding a color pigment to the rust preventive paint, a colored rust preventive paint can be obtained. However, it is not possible to obtain a coating film that vividly develops color simply by adding a color pigment. The inventors of the present invention have found that blending metal powder in the rust-preventing paint is one factor that reduces the vividness of the color of the coating film, and that the influence of aluminum powder is particularly great. When a rust preventive paint is used as a colored rust preventive paint to which a color pigment is added, a coating film that vividly colors can be formed by using a colored aluminum powder previously colored with a color pigment.

  Unlike the aluminum powder, the zinc powder in the metal powder has a small effect on the vividness of the color of the coating film. Therefore, the zinc powder is blended without being colored. Thereby, the coating film formed with the rust preventive paint has vivid color and has a sufficient rust preventive effect due to the sacrificial anticorrosive action of zinc.

  The shape of the metal powder as the coating material is preferably a scaly shape (a scaly shape) so as to have high corrosion resistance even when the thickness of the coating is reduced. By being scaly, it is realized that the metal powder is laminated in the thickness direction in the film. Even if a crack is generated in the film due to shrinkage caused by the polymerization of the binder component, this laminated structure suppresses the progress and prevents the generation of a large crack that exposes the substrate.

  The average thickness of the scale-shaped metal powder is 1/200 to 1/2 of the average thickness of the film, and the average value of the major axis of the metal powder (the length of the longest part of the scale shape) is the average of the film It is preferable that it is 1 / 20-10 times with respect to thickness. For example, when the film is about 10 μm, the average thickness of the scale-shaped metal powder is preferably 0.05 to 5 μm, and the average value of the major axis is preferably 0.5 to 100 μm.

  Even if the coating thickness varies depending on the coating conditions, the average value of the major axis of the metal powder is in the range of 1.0 to 50 μm, particularly preferably in the range of 4.0 to 20 μm. In the case where the average thickness of the scale shape is in the range of 0.05 to 1.0 μm, particularly preferably in the range of 0.05 to 0.5 μm, cracks are hardly generated even by the baking treatment, and excellent antirust properties A coating film having the following is obtained.

  In addition, when the average value of a major axis is smaller than said range, it becomes difficult to obtain the structure where the scaly metal powder was laminated | stacked within the membrane | film | coat, and it comes to show the tendency for the inhibitory effect of a crack progress to become small. On the other hand, when it is larger than the above range, the distribution of the metal powder becomes sparse, which may adversely affect the rust prevention characteristics.

  In addition, when the average thickness of the scale shape is smaller than the above range, it becomes easy to be destroyed during the stirring and kneading operation of the paint, the scale shape is hardly formed, and the laminated structure is hardly obtained. On the other hand, when it is larger than the above range, it is difficult to obtain a structure in which a plurality of metal powders are laminated in the thickness direction of the film, and the effect of suppressing the progress of cracks may be reduced.

  The composition ratio of the metal powder in the paint is preferably mass% relative to the total paint, and is preferably in the range of 5 to 60%, more preferably 5 to 40%. When the amount is too large, it becomes difficult to apply the coating in a thin film state, and the strength of the film is lowered. On the other hand, if the amount is too small, cracks are likely to progress, and the rust preventive function of the film is reduced.

(Organic solvent)
When the rust-preventive coating material of the present invention contains an organic solvent in the coating operation, it is possible to obtain a film having good adhesion to the member to be coated and high adhesion. In addition, regarding various additives added at the time of forming a coating material, a wide variety of additives can be used by including an organic solvent.

  Suitable organic solvents include alcohols such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, methoxybutanol, methoxymethylbutanol, esters of these alcohols, esters such as propionate, ethylene glycol, diethylene glycol And glycols such as triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol, and ethers of these glycols such as monomethyl ether, monoethyl ether and monobutyl ether. Moreover, you may use hydrocarbons, such as toluene, xylene, mineral spirit, and solvent naphtha. These may be used alone or as a mixture of several kinds.

The amount of the organic solvent varies depending on the working environment, but is preferably 10 to 60% of the total coating material, more preferably 15 to 45%, and particularly preferably 20 to 30%. If this range is exceeded, it may be difficult to obtain a thin film, or it may be difficult for the metal powder to form a laminated structure in the film, and there may be a relationship with the content of other components, but it may be difficult to obtain the desired film. sell.

(Color pigment)
As the coloring pigment, commonly used organic pigments and inorganic pigments can be used, but organic pigments are preferred because of vivid color tone. Examples of organic pigments include permanent red, first yellow, and phthalocyanine green, and examples of inorganic pigments include titanium dioxide, red pepper, bitumen, iron oxide, and carbon black. These may be used alone or as a mixture of several kinds. From the viewpoint of improving the dispersibility in the coating composition, the colored pigment is preferably blended as a pigment dispersion in which the colored pigment is previously dispersed in a dispersion medium. The blending amount of the pigment dispersion is preferably 5 to 60% by mass, more preferably 10 to 40% by mass of the anticorrosive paint.

(Other additives)
The rust preventive paint of the present invention can contain various additives generally used in the paint as necessary. Examples of such additives include thickeners, rust preventive pigments, colloidal silica fine particles, and the like.

Examples of the thickener include fatty acid amides, polyamides, polyethylene oxide, hydroxypropyl cellulose, and silicate inorganic thickeners.
Examples of the rust preventive pigment include zinc phosphate, magnesium phosphate, zinc molybdate, and aluminum phosphomolybdate.

  The colloidal silica fine particles are sol-like silica particles having a particle diameter finer than 1 μm, and have the effect of improving the corrosion resistance and film strength of the film, similar to the silicon compound described above. Examples of the colloidal silica fine particles include organosilica sol (for example, Snowtex manufactured by Nissan Chemical Industries, Ltd.) in which colloidal silica is dispersed in an organic solvent, fumed silica (vapor phase silica), and the like.

In addition, conventional paint additives such as a wetting agent and an antifoaming agent can be contained in the paint of the present invention.
These other additives are preferably added in a total amount in the range of 0.1 to 10% of the total paint. If the amount is less than 0.1%, the effect of the additive may not be obtained. If the amount exceeds 10%, the composition ratio of the metal powder and binder component as the main agent is relatively lowered, and rust prevention is a basic characteristic. There is a risk that the characteristics will deteriorate.

As for each component which comprises the rust preventive coating material of this invention described above, all can use 1 type (s) or 2 or more types.
The anticorrosive paint of the present invention is prepared by sufficiently stirring and mixing the above-described components and uniformly dispersing the metal powder in the liquid.

  The steel members to which the rust preventive paint can be applied include all steel members from steel plates, rods, steel pipes and die steels to small articles such as molded products and bolts. The steel member may be subjected to a treatment widely used as a coating pretreatment for improving coating adhesion and corrosion resistance, such as shot blasting and phosphate coating.

  Application of the coating material to the steel member can be performed by, for example, conventional methods such as roll coating, spraying, brush coating, and dipping, and an appropriate coating method may be selected according to the form of the member. The coating is preferably performed so that the thickness of the film formed after the heat treatment is in the range of 2 to 30 μm.

  The heat treatment (baking) after coating is performed at 200 to 400 ° C. for 10 to 120 minutes. By the heat treatment, the organosilicon compound undergoes a condensation reaction using the organotitanate compound as a curing agent or catalyst, and a film containing a large amount of metal powder is formed on the surface of the steel member. Prior to the heat treatment, preheating may be performed for drying.

  Thus, the steel member to which the paint of the present invention has been applied exhibits a long-term rust prevention effect even if it is used as it is, but it can be further coated if desired.

EXAMPLES Hereinafter, although this invention is further demonstrated using an Example, this invention is not limited to the aspect of an Example.
1. Preparation of Test Pieces According to the formulation (parts by mass) shown in Table 1, the components were mixed well by stirring together for 3 hours using a high-speed stirrer for paint, and Examples 1 to 3 and Comparative Example 1 and 2 paints were prepared.

First, scaly zinc powder was prepared as follows.
100 parts by weight of metal zinc powder having an average particle size of 5 μm was dispersed in 200 parts by weight of mineral spirit, and a small amount of fatty acid was added to form a slurry having a dispersion concentration of metal zinc powder of about 30% by weight. This slurry is pulverized with a bead mill (Star Mill ZRS manufactured by Ashizawa Finetech Co., Ltd.), and the slurry after the treatment is evaporated and dried under reduced pressure. A 0.3 μm-flaky zinc powder was obtained.

Moreover, the following were used for the scaly aluminum powder and the colored aluminum powder.
Uncolored aluminum powder (scale-like): Toyo Aluminum Co., Ltd. Alpaste 0200M (product name, average diameter 10 μm, average thickness 0.2 μm)
Red aluminum powder (scale-like): Colored Al paste D451RE (product name, average diameter 11 μm) manufactured by Toyo Aluminum Co., Ltd.
-Yellow aluminum powder (scale-like): Colored Al paste D452YE (product name, average diameter 11 μm) manufactured by Toyo Aluminum Co., Ltd.
Blue aluminum powder (scale-like): Colored Al paste D452BL (product name, average diameter 11 μm) manufactured by Toyo Aluminum Co., Ltd.

As the other components shown in Table 1, the following were used.
-Ethyl polysilicate: Colcoat Co., Ltd. ethyl silicate 40 (product name)
Tetrabutoxy titanium polymer: Nippon Soda Co., Ltd. TBT polymer B-10 (product name)
-Red pigment dispersion: NX-032 Red (product name) manufactured by Dainichi Seika Kogyo Co., Ltd.
・ Yellow pigment dispersion: NX-011 Yellow (product name) manufactured by Dainichi Seika Kogyo Co., Ltd.
Blue pigment dispersion: EMU Blue 870AF-1 (product name) manufactured by Toyocolor Co., Ltd.
・ Dispersant (polyethylene oxide): manufactured by Enomoto Kasei Co., Ltd.
・ Thickener (Organic bentonite): Made by Nippon Organic Clay Co., Ltd.

  Next, each paint was applied to a mild steel plate previously degreased and washed by a bar coater, and heat treatment was performed at 280 ° C. for 30 minutes to form a coating film having a thickness of 20 μm.

2. Evaluation method (1) Color tone Whether or not the mild steel sheet having the coating film formed on the surface thereof was colored without turbidity by the above-described method was visually determined using the following criteria.
○: There is no turbidity and the color is fine.
X: There is turbidity and it cannot be colored neatly.
(2) Corrosion resistance with scratches A mild steel sheet on which a coating film of an anticorrosive paint was formed was used as a test piece. A cross-cut was made with a cutter knife so as to reach the substrate (soft steel plate) to the test piece to obtain a test piece for evaluation.
Corrosion resistance was evaluated by observing the progress according to the salt spray test JIS Z 2371 and evaluating the time from the start of the test to the occurrence of red rust at the cross-cut portion of the test specimen for evaluation.

3. Test Results Table 2 shows the results of evaluating (1) color tone and (2) scratched corrosion resistance using the evaluation method described above. As shown in Table 2, by using a pigment dispersion as a coloring pigment and a colored aluminum powder in combination, it is possible to achieve coloring without turbidity by the anticorrosive paints of Examples 1 to 3, that is, a coating film that vividly develops color. Could be formed. In addition, the coating film of the anticorrosive paint had good scratch resistance and corrosion resistance.

The present invention is useful as a rust-preventing paint applied to precision equipment and steel plates for press molding of automobiles because it can impart a high rust-preventing function to a thin film and can give a vivid color.

Claims (4)

Based on the total paint, 5 to 40% by mass of the organosilicon compound, 0.05 to 2% by mass of the organic titanate compound, 5 to 60% by mass of the metal powder composed of zinc powder and colored aluminum powder, and 10 to 60 of the organic solvent. Containing mass% and a coloring pigment ,
The zinc powder is not colored and the content thereof is 3 to 9% by mass based on the total coating material.   2. The anticorrosive paint according to claim 1, wherein the organosilicon compound is at least one compound selected from the group consisting of tetraalkylsilicate compounds having an alkyl group having 3 or less carbon atoms and oligomers thereof. The organic titanate compound is an organic compound represented by the general formula Ti (X) ₄ and an oligomer thereof, wherein X is methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, and tert-butoxy having 4 or less carbon atoms. Or at least one functional group selected from the group consisting of a chelating substituent including an alkoxy group, lactate, triethanolaminate, acetylacetonate, acetoacetate, and ethylacetoacetate, and a hydroxyl group. 2. Anticorrosive paint according to 2.   The rust preventive paint according to any one of claims 1 to 3, wherein the metal powder is scaly.