JP2991293B2 - Zinc rich paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-rich paint composition, and more particularly, to a zinc-rich paint composition containing whisker-like calcium carbonate, which is excellent in coating workability, is capable of thick film coating, and has high corrosion resistance. The present invention relates to a coating composition.

[0002]

2. Description of the Related Art Zinc rich paint in which a relatively large amount of zinc dust is mixed with a binder is widely used for the purpose of preventing corrosion of ships, bridges, tanks, plants, marine structures and the like. The zinc-rich paint is roughly classified into an organic zinc-rich paint and an inorganic zinc-rich paint depending on the type of a binder used.

[0003] Organic zinc-rich paints are generally obtained by adding a large amount of zinc dust to a binder such as an epoxy resin, so that the base adjustment work and the painting work are easy and the top coat applicability is good. Although it has certain characteristics,
Since the anticorrosion function and cohesion of the coating are somewhat insufficient, they are not often used when long-term anticorrosion is important. In contrast, inorganic zinc-rich paints generally use an alkyl silicate resin as a binder,
Because of the excellent anticorrosion function and durability of the coating film, it is especially suitable for long-term anticorrosion of large steel structures.
The coating workability is not easy, and therefore it is necessary to carefully adjust the base such as polishing and blasting of the base. Attempts have been made to add anti-flow agents for the purpose of improving the coating workability, but the effect is small. Further, attempts have been made to balance the coating workability and the anticorrosion function by combining an inorganic binder and an organic binder.

[0004] However, in all zinc-rich paints, a high concentration of zinc dust has conventionally been focused on the anticorrosion function, but the coating workability, especially when the wet film thickness is 200 μm or more in one coating, is applied. However, there is no proposal that is satisfactory in terms of preventing sagging and cracking of the coating film during spraying and sprayability.

[0005] For example, in the case of inorganic zinc-rich paint, it is difficult to apply a wet film thickness of 200 μm or more by one coating even if the base material is sufficiently adjusted.
Even if the anti-flow agent is added, dripping is unavoidable, and even if the coating is applied over a long period of time, if the dry film thickness exceeds 200 μm, cracks, peeling off from the undercoat or overcoat easily occur, and the anticorrosion function Cannot be fully demonstrated. Further, even in the case of an organic zinc silicate which is considered to be excellent in coating workability, if the amount of zinc dust is not appropriate, the zinc silicate may be sagged, and cracking of the coating film is a problem. In addition, sedimentation of zinc dust during storage of paint is also a problem.

In JP-A-63-17976, the coating operation is improved while preserving the corrosion resistance of the zinc-rich paint by coating the zinc powder with a flow stopper in advance. A method for preventing the occurrence of cracks is disclosed. However, the generation of cracks cannot be sufficiently suppressed only by coating the zinc dust with a flow stopper. Further, Japanese Unexamined Patent Publication No.
No. 81370 describes a rust-preventive coating composition containing acicular or long columnar calcium metasilicate to prevent cracking and peeling of a coating film.
In thixotropic coating compositions containing acicular and / or fibrous substances, fibrous clay minerals such as acicular calcium silicate (wollastonite), sepiolite, serpentine lizatite, or potassium titanate, gypsum Fiber, slag fiber,
Rock wool, glass fiber, etc.
Improved anti-scattering properties. However, these needle-like or fibrous substances have poor mesh permeability, so that the yield in preparing the powder component in the pre-process of paint production is poor, resulting in blending fluctuations, and the use of coating equipment during coating. There was a problem that the spray was clogged.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to improve the ability of powder components to pass through a mesh.
An object of the present invention is to provide a zinc-rich paint which exhibits excellent anticorrosion properties, improves coating work, improves adhesion to a base coat or a top coat even in the case of thick coating, and can prevent the occurrence of cracks.

[0008]

Means for Solving the Problems In order to solve such problems of paint workability and crack prevention, the present inventors have proposed:
As a result of intensive research on fillers for zinc-rich paint, it was found that the desired purpose was achieved by adding a specific whisker-like calcium carbonate, and the present invention was completed.

That is, the present invention is characterized in that a zinc rich paint composition containing a binder and zinc dust as main components contains whisker-like calcium carbonate having a major axis of 5 to 50 μm and an aspect ratio of 4 or more. It contains a zinc-rich paint composition.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The whisker-like calcium carbonate of the present invention preferably has a particle diameter of 5 to 50 μm and an aspect ratio of 4 or more. More preferably, the major axis is 20 to
The particle size is 30 μm. If the major axis is less than 5 μm, cracks in the coating film tend to occur, and the coating tends to corrode. Also,
If the major axis exceeds 50 μm, the sieving property tends to be poor, and the workability of the spray during the coating operation tends to be poor. Such a whisker-like calcium carbonate is easily produced, for example, by the method described in JP-A-3-88714.

The whisker-like calcium carbonate used in the present invention is preferably surface-treated with a silicone-based treating agent, a titanate-based coupling agent, a carboxylic acid-based surface treating agent, a sulfonic acid-based surface treating agent, or the like. These surface treatment agents can be used alone or in combination of two or more.
More preferably, surface treatment with a silicone-based silane coupling agent is preferred. The surface treatment of the whisker-like calcium carbonate changes the surface state and reduces the bulk of the powder, thereby improving the sieve passage property and the coating workability.

The silicone-based treating agent is a silicone-based surface modifying agent, which is a compound having a reactive silyl group in a molecule and a silicate or polysilicate such as silicone oil or silicone emulsion. The silane coupling agent is an organosilicon monomer having two or more different reactive groups, and specifically, vinyl silane, acryl (methacryl) silane, epoxy silane, amino silane, mercapto, chloropropyl silane It is a coupling agent. Monomers and partial condensates (tetraalkoxysilicate) having one type of reactive group are methyl silicate, ethyl silicate, propyl silicate, isopropyl silicate, butyl silicate, and isobutyl silicate monomers and partial condensates. is there.

The titanate-based surface treating agent is represented by the following structural formula. _{(XO) nTi (OR) 4} -n wherein, XO: R'COO, (R " O) 2 P (O) O or the like RO: a lower alkoxy group n: 1 to 3

One of the carboxylic acid surface treating agents is α,
a polymer of a β-unsaturated carboxylic acid monomer, an alkali salt thereof,
A type consisting of a partially or completely neutralized product with an ammonium salt and an amine, containing a hydroxyl group and a carboxyl group obtained by copolymerizing an α, β unsaturated carboxylic acid and an α, β unsaturated carboxylic acid hydroxy ester. Is preferred. The other one is a fatty acid-based treating agent, and higher fatty acids or saturated salts of saturated fatty acids or unsaturated fatty acids can be used.

The sulfonic acid-based surface treating agents include alkyl ether sulfuric acid, alkyl aryl ether sulfuric acid, alkyl sulfate, alkyl aryl sulfate, alkyl amide sulfate, alkyl sulfonic acid, alkyl naphthalene sulfonic acid, α-olefin sulfonic acid, N- Acyl sulfonic acid, perfluoroalkyl sulfonic acid and the like.

The amount of the surface treating agent to be treated is 0.1 to 5% by weight, preferably 0.2 to 3.0% by weight, more preferably 0.5 to 2% by weight, based on the whisker-like calcium carbonate.
0% by weight. When the surface treatment amount is less than 0.1% by weight, the sieve passage property may be deteriorated. On the other hand, when the surface treatment amount is more than 5% by weight, the binder is adversely affected, and the crack preventing effect may not be sufficiently exhibited.

The surface treatment of the whisker-like calcium carbonate may be any of a wet method and a dry method. In the case of wet surface treatment, a surface treating agent may be added to the whisker-like calcium carbonate water or solvent slurry.In the case of dry treatment, a powder stirring device such as a Henschel mixer or ribbon mixer may be used. it can. Also,
It is also possible to perform a surface treatment during mixing with the zinc powder during coating compounding.

As the binder for the zinc-rich paint of the present invention, a partially hydrolyzed polyalkyl silicate or a modified product thereof can be mentioned. For example, tetramethyl orthosilicate, tetraethylorthosilicate, tetrapropylorthosilicate, tetrabutylorthosilicate, tetrapentylorthosilicate, tetrahexylorthosilicate, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane , Ethyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, amyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, etc.
The hydrolysis rate in this case is preferably 50 to 98%. These hydrolysates may be derivatives reacted with other organic polymer compounds. These may be used alone or in combination of two or more.

More specifically, ethyl silicate 40 (manufactured by Colcoat Co., Ltd.), ethyl silicate 40 (manufactured by Tama Chemical Industry Co., Ltd.), Silbond 40 (Stauf)
fer Chemical Co. Manufactured), Ethyl
Silicate 40 (Union Carbide
Co. These materials are usually dissolved in a solvent and hydrolyzed under an acid catalyst.

The binder may be a mixture of a partial hydrolyzate of the polyalkyl silicate or a modified product thereof and an organic polymer compound compatible with them. Examples of such high molecular compounds include, for example, polyvinyl acetal, for example, having a polymerization degree of 200 or more and 2000 or more.
In the following, those having a degree of acetalization of 60 to 70%, specific examples thereof include formal and butyral: cellulose derivatives such as cellulose esters such as acetylcellulose and nitrocellulose, methylcellulose, ethylcellulose, benzylcellulose and carboxymethylcellulose. Cellulose ethers: epoxy resins, for example, glycidin ethers of alkylene glycol polyethers, for example, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polyoxytetramethylene glycol diglycidyl ether and the like. These may be used alone or in combination of two or more.

According to the present invention, even when only the organic binder such as an epoxy resin or a polyamide resin is used as the binder, the coating workability such as spraying and the like and the thick film coating property are improved, and the good anti-corrosion property of the film properties is obtained. A coating is obtained.

The zinc powder used in the present invention is Zn powder.
Can be used as long as it elutes and has a sacrificial anode effect. The particle size of zinc powder is usually 1
１００100 μm is used.
Those having a particle size in the range of μm are preferred. The use of particles in this preferred particle size range makes it possible to obtain a coating film having better workability during coating and a more uniform appearance. The amount of zinc dust to be blended in the paint of the present invention is not particularly limited, but is usually 4% of the total blended solid components.
It is good to mix zinc powder so as to be 0 to 95% by weight, preferably 50 to 92% by weight.

The amount of the whisker-like calcium carbonate used in the present invention is usually from 0.5 to 50% of the total solid component.
% By weight, preferably 1 to 30% by weight, more preferably 2% by weight.
It is better to mix so as to be ２０20% by weight. If the amount is less than 0.1% by weight, it is difficult to sufficiently exert the effect of preventing cracks in the coating film. If the amount is more than 50% by weight, the workability of spraying is deteriorated, and ethyl silicate and the like are not bonded. There is a tendency that the condensation of the agent is accelerated and the pot life after the compounding of the paint is shortened.

[0024] As other compounding agents, anti-sagging agents, pigments and the like can be compounded. As an anti-sagging agent,
It is usually added to paints to develop structural viscosity and impart thixotropic properties to the paints, such as amorphous silica, colloidal calcium carbonate, organic bentonite, hydrogenated castor oil, aliphatic amides, higher fatty acids, and microgel particles. These are used singly or in combination of two or more. Particularly, an organic bentonite-based sagging agent is preferable because a large amount of structural viscosity can be exhibited by adding a small amount thereof.

As the pigment, extender pigments, rust-preventive pigments, and color pigments used in ordinary rust-preventive paints can be used. Specifically, talc, mica, barium sulfate, clay, calcium carbonate, zinc white, titanium white, red iron,
Examples include zinc phosphate, aluminum phosphate, barium metaborate, aluminum molybdate, iron phosphide, and the like, and these may be used alone or in combination of two or more.

The paint can be prepared according to a conventional method,
For example, a liquid component containing a binder, a powder component of zinc powder and whisker-like calcium carbonate are separately prepared, and the powder component is mixed with a powder component such as zinc powder and whisker-like calcium carbonate using a Henschel mixer or the like. Pass through and fill container. In general, a method of mixing the two immediately before use is used for actual coating. For dispersion of liquid component and powder component,
It can be dispersed by a media mill such as a roll mill, a sand grind mill, a ball or the like, which is a usual disperser, or a disperser. The zinc-rich paint made in this way is air spray, airless spray, roll coater,
It is applied to a steel structure or the like by means such as brushing, and is generally applied by spraying.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following description, "part",
“%” Represents “parts by weight” and “% by weight” unless otherwise specified.

Examples 1 to 8, Comparative Examples 1 to 5 (A) Whisker-like calcium carbonate (1) Preparation of whisker-like calcium carbonate (no surface treatment) As shown in Table 1, whisker-like calcium carbonates having different particle diameters Was prepared.

[0029]

[Table 1]

(2) Preparation of surface-treated whisker-like calcium carbonate f, g and j (dry method) 2.5 kg of whisker-like calcium carbonate a (Whiscal A manufactured by Maruo Calcium Co., Ltd.) shown in Table 1 was mixed with a supermixer (Co., Ltd.). The mixture obtained by copolymerizing α, β unsaturated carboxylic acid and α, β unsaturated carboxylic acid hydroxyester was added to whisker-like calcium carbonate at 1.0% to 10% slurry while mixing, stirring and mixing. And spraying 1.0% on whisker-like calcium carbonate as a 20% slurry with a silane coupling agent (KBM-603γ-aminopropyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd.).
Heat treatment was performed for a period of time to obtain a coupling-treated whisker-like calcium carbonate f as shown in Table 2. Also, except that the surface treatment agent was changed as shown in Table 2,
Surface-treated whisker-like calcium carbonate g and j were obtained.

(3) Preparation of surface-treated whisker-like calcium carbonates h and i (wet method) 3 kg of whisker-like calcium carbonate a shown in Table 1 (Whiscal A manufactured by Maruo Calcium Co., Ltd.) was stirred in 30 L of warm water using a stirrer. Well dispersed. In this slurry, 30 g of sodium stearate (reagent) (1.0% based on whisker-like calcium carbonate) is dissolved in hot water,
The slurry was added with stirring, dehydrated by a conventional method,
The mixture was dried and crushed at 100 ° C. for 24 hours to obtain whisker-like calcium carbonate h treated with stearic acid as shown in Table 2.
A surface-treated whisker-like calcium carbonate i was obtained in the same manner as described above, except that the surface treatment agent was changed as shown in Table 2. Surface-treated whisker-like calcium carbonate f,
Table 2 shows the powder bulks of g, h, i and j.

[0032]

[Table 2]

(B) Zinc rich paint composition (1) Preparation of powder component Zinc powder having an average particle size of 15 μm (manufactured by Mitsui Kinzoku Mining Co., Ltd.)
The above-mentioned whisker-like calcium carbonates a to j were added to 100 parts, mixed with a Henschel mixer, and passed through a 120-mesh vibrating sieve to prepare a zinc-rich paint powder component.

(2) Preparation of binder Ethyl silicate condensate (Ethyl silicate 40 manufactured by Colcoat Co., Ltd.) and isopropyl alcohol were mixed and hydrolyzed to obtain a binder for zinc rich paint. At this time, the hydrolysis rate was 95%, and the nonvolatile content was 2%.
0%. The hydrolysis rate is defined as ethyl silicate 4
0 means the amount of water when the stoichiometric amount of water that changes to SiO ₂ by hydrolysis is defined as 100% of hydrolysis.

(3) Preparation of paint Whisker-like calcium carbonate a to
j and k: colloidal calcium carbonate (Calfine 20)
0, manufactured by Maruo Calcium Co., Ltd .; l: wollastonite (NYAD1250, manufactured by Nagase Sangyo Co., Ltd.); m: talc (LMS200, manufactured by Maruo Calcium Co., Ltd.) with the following composition using a sand grinder mill. , Zinc rich paint was evaluated. Formulation example Zinc powder concentration 85% Sample (whisker-like calcium carbonate) 5% Binder 10%

The evaluation was conducted by applying a zinc-rich paint to a steel sheet,
The following evaluation was performed. The results are shown in Tables 3 and 4.

(A) Screening property of sieve The passing property and yield (%) of the powder component at 120 mesh are shown.

(A) Rust prevention The degree of occurrence of red rust is indicated by ◎ to ×. The standard is ASTM-
In D610 / SSPC-Vis2, 9 to 10 points were rated as ◎, 7 to 8 points as ○, 5 to 6 points as Δ, and 1 to 4 points as ×.

(C) Substrate adhesion A shotplast steel plate (manufactured by Nippon Test Panel) was applied by air spray and dried for one week in a room adjusted to 20 ° C. and 75% RH. A Goban-mesh tape test was performed and evaluated by a 10-point scale of 1 to 10 points.

(D) Cracked Film Thickness The presence or absence of cracks in the coated plate dried under the same conditions as in (c) was visually determined, and the film thickness at the time of crack generation was measured. The judgment was as follows: film thickness> 150 μm
0 μm for ○, <100 to 50 μm for Δ, film thickness <50 μm
Is indicated by x.

(E) Precipitation of Pigment The non-volatile component of the paint was adjusted to 60%, and the state of standing at 20 ° C. for 5 hours was observed. These observation results are indicated by ◎ to × according to the following criteria. A: Very good without any sediment. ：: Soft sediment is slightly present, but easily redispersed. Δ: Most of the pigment components softly settled, and redispersion took time. ×: A hard cake is formed, and a long time is required for redispersion.

(F) Airless Sprayability Using an airless spray device with a compression ratio of 30: 1, using a tip size of 163-619 (manufactured by Nippon Gray Co., Ltd.) at a primary pressure of 3 kg / cm ² , the nozzle tip can be clogged. Checked and indicated by ◎ to に よ り according to the following criteria. A: Continuous spraying is possible with almost no clogging of chips. ：: There is clogging about once every 30 minutes, but there is no problem in sprayability. Δ: Clogging occurred once or more in a few minutes, and continuous spraying was impossible.

[0043]

[Table 3]

[0044]

[Table 4]

Examples 9 to 15 Using whisker-like calcium carbonate g, the composition was changed as shown in Table 5 to prepare zinc-rich coatings, which were evaluated. Table 5 shows the composition and the evaluation results.

[0046]

[Table 5]

[0047]

As described above, the zinc-rich paint composition of the present invention has good sieving property and excellent coating workability, has good substrate adhesion, prevents cracking, and has good thick film coating properties. Are better.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-259853 (JP, A) JP-A-63-17976 (JP, A) JP-A-2-212530 (JP, A) JP-A-3-3 88714 (JP, A) JP-A-60-13864 (JP, A) JP-A-59-36157 (JP, A) JP-A-6-9928 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09D 1/00-201/10 C08K 1/00-13/08 C08L 1/00-101/14

Claims (7)

(57) [Claims] 1. A zinc-rich paint composition comprising a binder and zinc powder as main components, comprising a whisker-like calcium carbonate having a major axis of 5 to 50 μm and an aspect ratio of 4 or more. Composition. 2. The zinc-rich paint composition according to claim 1, wherein the content of the whisker-like calcium carbonate is 0.5 to 50% by weight. 3. The whisker-like calcium carbonate is surface-treated with at least one of a silicone surface treatment agent, a titanate coupling agent, a carboxylic acid surface treatment agent, and a sulfonic acid surface treatment agent. A zinc rich paint composition as described in the above. 4. The zinc-rich paint composition according to claim 1, wherein the content of zinc powder is 40 to 95% by weight. 5. The zinc-rich paint composition according to claim 1, wherein the binder is a partially hydrolyzed polyalkyl silicate or a modified product thereof. 6. The zinc-rich paint composition according to claim 1, wherein the binder is an organic polymer compound. 7. The zinc-rich paint composition according to claim 6, wherein the organic polymer compound is an epoxy resin or a polyamide resin.