JPS6317976A - Zinc-rich paint composition - Google Patents

Abstract

PURPOSE:The titled composition, consisting essentially of zinc dust prepared by precoating with a specific amount of an antirunning agent and binder, capable of improving the coating operability while holding corrosion resistance and above all thick coating without causing sagging or cracks of films and useful for preventing corrosion of ships, etc. CONSTITUTION:A composition, consisting essentially of (A) 55-92wt% (weight ratio of solid in the composition) zinc dust prepared by precoating with an antirunning agent, e.g. consisting of the group of amorphous silica, precipitated calcium carbonate, bentonite, hydrogenated castor oil, fatty acid polyamide, higher fatty acid and carbon, and (B) a binder (partial hydrolyzate or modified polyalkyl silicate), capable of preventing settling of the zinc dust in the binder and having improved storage stability and adhesive property.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a zinc-rich paint composition that contains a high concentration of zinc powder that has been pre-coated with an anti-flow agent, has excellent coating workability, and is suitable for thick film coating. The present invention relates to a coating composition with high corrosion resistance.

Conventional technology Zin-frich paint, which is a binder mixed with a relatively large amount of zinc powder, is widely used for corrosion protection of large steel structures such as ships, bridges, tanks, plans, and offshore structures. Such zinc-rich paints are classified into organic zinc-rich paints and inorganic zinc-rich paints, depending on the type of binder used.

Organic zinc-rich paints generally contain a large amount of zinc dust in a binder such as an epoxy resin, and have the characteristics of being easy to prepare the base, easy to paint, and suitable for overcoating. On the other hand, since the anticorrosion function and cohesive force of the coating film are somewhat lacking, it is not used very often when long-term corrosion protection is important. On the other hand, inorganic zinc-rich paints generally use alkyl silicate-based resins as binders, which impairs the anti-corrosion function and durability of the paint film, making them particularly suitable for long-term corrosion protection purposes for large steel structures. However, it is not easy to prepare the substrate, paint, etc., and therefore, it is necessary to carefully prepare the substrate by polishing or blasting the substrate. Attempts have been made to add anti-flow agents to improve the ease of coating, but the effect is small.

Furthermore, attempts have been made to combine inorganic binders and organic binders to balance painting workability and corrosion protection.

However, conventionally, all types of zinc-rich paints have focused on anti-corrosion functionality and have contained zinc powder at a high concentration of 85 to 95% by weight, but there have been problems with painting workability, especially the ability to form a wet film with one coat. It was not sufficient in terms of sagging when applied to a film with a thickness of 200 μm or more, cracking of the coating film, generation of dust during air spraying, etc. For example, with inorganic zinc-rich paint, even if the substrate is sufficiently prepared, it is difficult to apply the same coating to a wet film thickness of 200 μm or more, and even if an anti-flow agent is added, sagging occurs, and it lasts a long time. Even after repeated coating over time, the dry film thickness remains 20%.
If it exceeds 0μ, mud cracks and peeling from the base or top coat are likely to occur, making it impossible to fully demonstrate the anticorrosion function. Furthermore, even in the case of organic zinc silicate, which is said to have excellent coating properties, sagging may occur if the amount of zinc powder is not appropriate, and cracks and scratches in the coating film are often a problem. There is. In addition, settling of zinc dust during paint storage is also a problem.

Problems to be Solved by the Invention Therefore, the workability of painting has been improved while maintaining the corrosion resistance of zinc-rich paint, which is mainly composed of a binder and zinc powder, and in particular, thick coating is possible and there is no sagging or coating film. There is a need for a coating composition that does not cause cracks and has excellent paint storage stability and substrate adhesion, and it is an object of the present invention to provide such a zinc-cured Sochi paint.

Means for Solving the Problems According to the present invention, the above object is to provide a zinc-rich paint composition containing a binder and zinc dust as main components, in which the zinc dust is an anti-flow agent in a weight ratio of 0.61 to 10% by weight. The solid content of the composition is 55 to 92% by weight.
This can be achieved by a zinc-rich pain composition (1) characterized in that it contains the following:

The present inventors first conducted a series of tests on the anti-corrosion properties of Shinkuri Sochi paint, which mainly consists of a binder and zinc dust, and found that the zinc dust content was at least 55% by weight based on the total solid content of the paint composition. It has been found that if the amount is less than this, the anticorrosion properties will be sharply reduced. In addition, from the viewpoint of corrosion resistance alone, the amount of zinc powder may be 95% or more, but if the amount of zinc powder is too large, the coating film will crack and the film forming properties will decrease, so the amount of zinc powder should be 55% or more. We found that 92% is the optimal range. Furthermore, as a binder, it is possible to select a partial hydrolyzate of polyalkyl silicate, a mixture with an organic polymer compound that is compatible with it, or an organic polymer compound such as an epoxy resin. Addition of amorphous silica, fatty acid bentonite, hydrogenated castor oil, fatty acid amide, higher fatty acid, etc., which are known as LL agents, has little effect on improving painting workability, and in particular, thick film coating properties and crack prevention properties are poor. However, when zinc powder is treated in advance with a specific amount of anti-flow agent and coated, it is surprisingly possible to achieve remarkable improvements in painting workability, thick film coating, and control of cracking. It was also found that precipitation of zinc dust in the binder was prevented, storage stability was improved, and adhesion was also improved. Based on these findings, the present invention was completed. It is.

As described above, the most characteristic feature of the present invention is that zinc powder, which has been treated in advance with a specific amount of anti-flow agent, is used in an amount of 55 to 92% by weight based on the total solid content of the coating composition.

The term "anti-flow agent" used in this specification generally shows a large interaction with organic polymer compounds used in inorganic zinc paints or organic zinc paints, and reduces structural viscosity. It means a substance that can be expressed, and typical examples include amorphous silica,
Examples include precipitated carbonate Calcylano 2 treated with fatty acid or resin acidification, bentonite treated with organic matter + 7 spoons, hydrogenated mustard oil, fatty acid polyamide, higher fatty acid, microshell particles, and the like. Of course, materials other than these may be used as long as they have a strong interaction with the organic polymer compound mentioned above and can exhibit structural viscosity.

Normal zinc powder, i.e. average particle size 1-20
μ may be of any shape, such as spherical or flat.

The anti-flow agent coating is conveniently formed by dispersing zinc powder and the anti-flow agent in a ball mill for 30 minutes to 48 hours so that the anti-flow agent is adsorbed onto the surface of the zinc particles. On this occasion,
A mortar may be used, and general dispersion equipment other than a ball mill may be used.

In the present invention, this anti-flow agent has a weight ratio of 0.1 to the zinc powder. , /99.9 to 10/90. This is because if the weight is less than 0.1% by weight, the anti-flow agent will not have sufficient effect and it will be difficult to make a thick film, and the effect of preventing zinc dust from settling will not be obtained. This is because not only no further improvement can be obtained, but also cracks tend to occur in the coating film and the pot life tends to be shortened.

The characteristics of the stream 1F cracked zinc powder of the present invention are most effectively exhibited when it is combined with a binder for an inorganic zinc-rich paint. Binders for such paint compositions include partially hydrolyzed polyalkyl silicates or modified products thereof. Representative of such binders are trimethyl orthosilicate, tetraethyl orthosilicate, tetraalopyl orthosilicate, tetrabutyl orthosilicate, trapentyl orthosilicate, tetrahexyl orthosilicate, methyltrimethoxysilane, methyltripropoxy silane,
Hydrogenation of alkyl siligate using raw materials such as methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, butyltrimethoxysilane, butyltrimethoxysilane', amyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, etc. It is an initial decomposition condensate, and the hydrolysis rate in this case is preferably 50 to 98%. Further, these hydrolysates may be derivatives reacted with other organic polymer compounds.

The binder may also be a mixture of a partially hydrolyzed polyalkyl silicate or a modified product thereof and an organic polymer compound compatible therewith. Examples of such polymer compounds include polyvinyl acetals, such as those with a polymerization degree of 200 to 2000 and acetalization degree of 60 to 75%, specific examples of which include formal, butyral, etc.; cellulose derivatives, such as acetalization. Cellulose esters such as cellulose and nitrocellulose, cellulose ethers such as methyl cellulose, ethyl cellulose, benzyl cellulose, and carboxymethyl cellulose (particularly preferred are ethyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, etc.): Epoxy resins, such as alkylene glycols Glycidyl ethers of polyethers, such as polyethylene glycol diglycidyl ether, polypropylene
'Glycol diglycidyl ether, polyoxytetramethylene glycol diglycidyl ether, and the like.

When using such a combination of inorganic and organic binders, the ratio of the former to the latter is preferably from 70/30 to 98/2 from the viewpoint of coating workability, storage stability, and physical properties of the coating film, and is particularly preferred. 85/'15~9515
It has also been confirmed that it is within the range of Even when only an organic binder such as epoxy resin or polyamide resin is used as the binder, the present invention further improves coating workability, thick film coating properties, storage stability, etc., and provides an anticorrosive coating with good film properties. It has been found that

In this way, in the present invention, zinc powder coated with a specific amount of flow agent is added to the binder, but as already mentioned, the zinc powder is 55-9
It is used in an amount of 2% by weight, preferably 75 to 85% by weight. This is because if the amount of zinc blended is too low, the corrosion protection will be insufficient, and if it is too much, the binder will inevitably be insufficient, making it easier for the coating to crack, and the film-forming performance will tend to deteriorate. It is.

In addition, in the composition of the present invention, normal zinc powder may be used in combination with the above-mentioned treated zinc powder. In this case, the same effect can be expected if the treated zinc dust accounts for 5% by weight or more of the total amount of zinc and the total amount of zinc dust is within a range of 92% by weight or less as a weight ratio of the total solid content of the composition. In the composition of the present invention, in addition to the above-mentioned treated zinc dust, zinc dust, and binder, various pigments, solvents, additives, etc. may be blended as necessary, as in ordinary antirust paints. Pigment components include ordinary extender pigments, anti-rust pigments, and coloring pigments, including talc, mica, barium sulfate, clay, calcium carbonate, zinc white, titanium white, red iron phosphate, zinc phosphate, aluminum phosphate,
Examples include barium metaborate, aluminum molybdate, phosphorous iron, and the like. Solvent components include normal isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, coal, butyl cellosolve, ethyl cellosolve, M
Examples include EK, MIBK, Doruor, Kijiroru, etc., and may be blended in an appropriate amount so as to obtain appropriate coating workability and coating film drying properties. As additive components, agents commonly used in anticorrosive paints such as wetting agents, reaction accelerators, color separation inhibitors, and anti-settling agents may be blended in appropriate amounts depending on the purpose.

The composition of the present invention can be prepared according to a conventional method by storing a liquid component containing a binder and a system containing other powder components in separate containers, and mixing the two immediately before use. Also, components that react with the binder (e.g. treated zinc dust, zinc dust)
A part or all of the other powder components may be dispersed together with a liquid component containing a binder, and the mixture and the remaining components may be mixed immediately before use. For dispersing the liquid component and the powder component, a common dispersing machine such as a roll mill, sand mill, Indian mill, ball mill, etc. may be used. In the composition thus obtained, the binder concentration may generally be 5 to 40% by weight, and the composition is applied to a steel structure by a conventional means such as air spray, airless spray, roll coater, shaving, etc. It may be dried by drying or hot air drying.

The present invention will be explained below with reference to Examples. Parts and percentages are by weight unless otherwise specified.

Production example 1 1 piece of porridge, MJll 7 former square salmon silicate u-ethyl silicate (ES40, manufactured by Nippon Colcoat Co., Ltd.) 100 parts IN-hydrochloric acid 8 parts ethanol
40 parts IPA
40 parts butyl cellosolve
Transfer 30 parts of the above formulation to a reactor and continue stirring for 3 hours while keeping the temperature at 60°C. The obtained solutions were used in Examples and Comparative Examples. Incidentally, the nonvolatile content of this solution after heating at 105° C. for 3 hours was 29%.

Example 1 Partial hydrolyzate solution of polyalkyl silicate of Production Example 1 16 parts Polyvinyl butyral (manufactured by Tanesui Kagaku Co., Ltd., trade name "S-LEC B")
H-3J) in 10% Butycello/fPA solution
10 parts talc
Part 3 mica
3 parts of the above formulation was dispersed in a stirrer for 1 hour to prepare a liquid base. Next, zinc powder (manufactured by Mitsui Kinzoku Mining Co., Ltd., product name
66.5 parts of C3J) and 1.5 parts of calcium carbonate (manufactured by Shiroishi Calcium Co., Ltd., trade name: Shiroenka CCRJ) were dispersed in a ball mill for 4 hours, taken out, and coarse particles were removed with a 350-mesh sieve to obtain treated zinc powder. was prepared.

The above liquid base and treated zinc powder were mixed and dispersed for 2 minutes using a stirrer to prepare a paint. Using this paint, test plates were prepared as described below and subjected to various tests. Table 1 shows the paint properties and test results of the coated plates.

Examples 2 to 13 and Comparative Examples 1 to 7 The same method as in Example 1 was repeated using the various raw materials listed in Table 1 to obtain paints, and the same tests as in Example 1 were conducted using these paints. The results are shown in Table 1.

Electron micrographs of the zinc dust used in Examples 1 and 2 ( x2390) are shown in the accompanying drawings, Figs. 1 and 2, and an electron micrograph (same magnification) of the zinc powder without using an anti-flow agent is shown in Fig. 3 (reference drawing).

(Left below) Evaluation test method [At room temperature, apply the sample paint solution to a glass plate using a sagging tester, immediately stand the glass plate vertically and let it stand for 30 minutes.
After 0 minutes, find the maximum film thickness without any abnormality (limit film thickness).

After leaving the coating film with a normal thickness obtained in the sagging test (below the critical thickness) for one week at 15-20°C, 30-50% R14, the coating film was removed. Observe with a 30x magnifying glass and determine the maximum film thickness without cracking.

If necessary, dilute the sample paint with thinner to adjust the viscosity to a range of 25 to 30 seconds using a #4 Ford cup. After leaving it at room temperature for 8 hours, measure the viscosity again and judge whether it is 60 seconds or less.

Kuno'1 Dilute the sample paint with thinner if necessary to adjust the viscosity to a range of 25 to 30 seconds using a #4 Ford cup. Next, with air spray (pneumatic 2.5KG/cm2), 20
The coating was applied perpendicularly to the surface to be coated from a distance of ~30 cIm, and the resulting coating film was visually observed to determine the degree of spray dust generation.

1 50 x 70 x 3 shot blasted
．． The prepared test paint was applied to one side of a 2a/n+ soft steel plate using air spray so that the dry film thickness was 75 to 100μ, and left for 120 hours under the conditions of 15 to 20'C130 to 50%R11. After that, the plate was immersed in 900 g of 3% saline solution at 20°C, and the potential of the plate was measured.

After that, the potential is measured every 24 hours and the saline solution is replaced with a new one.
IV), and the corrosion resistance is judged based on the number of days (number of times).

-Nine-

[Brief explanation of drawings]

Figures 1 and 2 of the accompanying drawings are electron micrographs (23 magnification) of zinc dust coated with the anti-flow agent used in the present invention.
90). Figure 3, for comparison, is an electron micrograph of zinc dust that has not been treated with anti-flow agent. patent application agent

Claims (6)

[Claims] (1) In a zinc-rich paint composition whose main components are a binder and zinc dust, the zinc dust is pre-coated with an anti-flow agent in an amount of 0.1 to 10% by weight, and the composition is solid. A zinc-rich paint composition characterized in that the zinc-rich paint composition is contained in a proportion of 55 to 92% by weight. (2) The anti-flow agent is amorphous silica, precipitated calcium carbonate, bentonites, hydrogenated castor oil, fatty acid polyamide,
The composition according to claim 1, which is at least one selected from the group consisting of higher fatty acids and carbon. (3) The composition according to claim 1, wherein the coating treatment of the zinc dust with the anti-flow agent is carried out by mixing and dispersing the zinc powder and a predetermined amount of the anti-flow agent in advance in a ball mill. (4) Claims 1 to 3, wherein the binder is a partially hydrolyzed polyalkyl silicate or a modified product thereof.
The composition according to any of paragraphs. (5) 70/30 to 98 in which the binder is a partially hydrolyzed polyalkyl silicate or a modified product thereof and an organic polymer compound that is compatible with the hydrolyzed polyalkyl silicate or a modified product thereof.
3. The composition according to any one of claims 1 to 3, which is a mixture in a weight ratio of 1 to 2. (6) The composition according to any one of claims 1 to 3, wherein the binder is an organic polymer compound such as an epoxy resin or a polyamide resin.