JP6313200B2 - Water-based anticorrosive paint composition - Google Patents

Description

  The present invention relates to a zinc dust-containing coating composition used for the purpose of rust prevention in large steel structures. More specifically, the present invention relates to a zinc dust-containing coating composition that is useful as an undercoat or overcoat for steel materials such as ships, offshore structures, plants, bridges, and onshore tanks and that can be diluted with water.

  Conventionally, epoxy resin coatings have been widely used for coating heavy-duty anticorrosive coatings on large steel structures due to their excellent characteristics such as corrosion resistance, adhesion, and chemical resistance. Also in ships, epoxy resin coatings have been used for many years especially in WBT (water ballast tanks) and have exhibited long-term corrosion resistance. However, the impact on the human body and the risk of fire caused by low flash point, low boiling point organic solvents such as xylene and toluene contained in epoxy paint have been regarded as problems. The PCPC rule established in 2007 by IMO (International Maritime Organization) requires a dry thick film of 320 μm by multilayer coating of epoxy paint in the WBT coating standards. Increasing the required coating thickness makes it more difficult to comply with the recent VOC regulations, and the increase in the number of man-hours related to painting causes a significant cost increase.

  As paints having good heavy anticorrosion properties, there are “zinc rich primer” and “thick film zinc rich paint” mainly composed of zinc metal powder as rust preventive paints for steel materials. These are paints mainly composed of zinc metal powder, epoxy resin (or alkyl silicate) as a binder, a curing agent and a solvent. More specifically, conventionally used zinc rich paints are roughly classified into organic zinc rich paints and inorganic zinc rich paints depending on the resin used as the vehicle, and the former mainly includes epoxy resins and curing agents (polyamides) as vehicles. , Amine adducts, etc.), and the latter is an alkyl silicate resin, both of which use an organic solvent as an essential component. These zinc-rich paints, when a corrosion battery is formed by permeated moisture, corrodes metal zinc powder in a high concentration instead of the iron base, that is, excellent corrosion resistance due to the electrochemical corrosion protection function. Show. From the above characteristics, zinc rich paint has been widely used as a solvent-based paint for forming a basic coating film of a heavy anticorrosion coating system.

However, these zinc rich paints are desired to emit no or almost no volatile organic solvent for the same reason as described above.
Aqueous alkali silicate binders containing zinc powder provide sufficient anticorrosion properties, but when immersed half times in the sea, blistering (local peeling of the coating) occurs over time and the area around the top of the draft section It has been found that the coating film dissolves. This is because the aqueous alkali silicate contains a large amount of alkali metal cations. Further, since such a paint has a low viscosity, it cannot be applied with an airless coating machine, and it is necessary to perform air spray coating using a pressure-feed pump. However, this coating machine cannot perform continuous painting, and the painting work takes time and is not practical.

  Thus, aqueous silica sols with very low alkali metal ion content are commercially available, but such coatings are very weak in adhesion, cohesion, hardness, and wear and water resistance. JP-T-2002-539317 proposes a water-based anticorrosive paint having a low alkali metal ion content and improved adhesion to a substrate and coating strength with respect to the above-mentioned properties in order to prevent the start and growth of blistering. Thick film construction is impossible, and it cannot be used as a top coat and expected to have long-term corrosion resistance.

  From the above, a zinc rich paint that can be used as an undercoating or overcoating, contains almost no organic solvent, cures at room temperature, and maintains good anticorrosion and physical properties over the long term is also desired.

  JP 2000-38394 A proposes a water-dispersible polyisocyanate compound containing a water-dispersible alkoxysilane group. Reference is also made to the use of the compounds as mixtures with isocyanate-reactive resins in aqueous two-component paints. However, such a paint could not be expected to have long-term corrosion resistance.

  In the case of conventional water-based inorganic zinc paints, since the resin component is only inorganic, the anti-sagging agent is not effective and the paint viscosity is low. Air spray painting using a pressure-feed pump was common. However, this coating machine cannot perform continuous painting, and the painting work takes time and is not practical. In addition, since zinc (zinc) is contained, it may sag when coated on the wall surface, or the resin component and zinc may be separated.

Special Table 2002-539317 JP 2000-038394 A

  The present invention seeks to solve the problems associated with the prior art as described above, and can be dispersed in water, has a low VOC, and is coated so that the dry film thickness is 250 μm or more. It is an object of the present invention to provide a water-based anticorrosive coating composition that is free from cracking of the coating film and sagging of the paint and that can give long-term anticorrosive properties to the steel sheet due to the sacrificial anticorrosive action of zinc. In addition, using epoxy resin paint, it can provide corrosion protection over a longer period of time compared to thick heavy-duty anticorrosion coating film formed in multiple steps, and can suppress corrosion of the steel sheet by sacrificial anticorrosive action even in damaged parts. An object of the present invention is to provide a water-based anticorrosive coating composition.

The present invention
A reaction solution (a) obtained by reacting a polyisocyanate compound having a hydrophilic site with a secondary amino group-containing alkoxysilane,
Zinc-containing powder (b),
Thixotropic agent (c),
And water (d)
A water-based anticorrosive coating composition comprising
In the reaction, the equivalent ratio (NCO / NH) of the isocyanate group of the polyisocyanate compound to the secondary amino group of the secondary amino group-containing alkoxysilane is 1.0 / 0.8 to 1.0 / 1.0. It is a certain water-based anticorrosive coating composition.

  In the water-based anticorrosive coating composition, the secondary amino group-containing alkoxysilane is preferably a compound represented by the following formula I and / or a compound represented by the following formula II.

（式中、３個のＸはそれぞれ有機基を表し、Ｘの少なくとも１個はアルコキシ基であり、Ｒ₁は炭素数１〜８の直鎖の、もしくは分岐したアルキル基またはフェニル基を表し、ｎは１〜８の整数である。）

(In the formula, each of three X represents an organic group, at least one of X is an alkoxy group, R ₁ represents a linear or branched alkyl group having 1 to 8 carbon atoms or a phenyl group, n is an integer of 1-8.)

（式中、３個のＸはそれぞれ有機基を表し、Ｘの少なくとも１個はアルコキシ基であり、ｎは１〜８の整数である）

(In the formula, three Xs each represent an organic group, at least one of X is an alkoxy group, and n is an integer of 1 to 8)

In the water-based anticorrosive coating composition, the hydrophilic portion of the polyisocyanate compound is preferably composed of an ethylene oxide chain or a sulfonic acid salt.
In the water-based anticorrosive coating composition, the thixotropic agent (c) is preferably composed of a bentonite compound thixotropic agent and / or a liquid thixotropic agent.
Another invention is an anticorrosion coating film formed from the water-based anticorrosion coating composition.
Another invention is a substrate with an anticorrosion coating film, wherein the surface of the substrate is coated with an anticorrosion coating film formed from the water-based anticorrosion coating composition.
Another invention is a substrate anticorrosion method including a step of applying the water-based anticorrosive coating composition.

  The water-based anticorrosive coating composition of the present invention is water-dispersible, has a low VOC, and has no problem of cracking of the coating film or sagging of the coating even when applied so that the dry film thickness is 250 μm or more. In addition, the sacrificial anticorrosive action of zinc can provide long-term anticorrosive properties to the steel sheet.

In addition, the water-based anticorrosive coating composition of the present invention can use less volatile organic solvent than conventional solvent-based zinc paints.
In addition, since the water-based anticorrosive coating composition of the present invention uses a resin component having both an organic system and an inorganic system, the resin itself is viscous and an anti-sagging agent is effective. For this reason, airless painting is possible, coating dust is difficult to be generated during airless painting, and smooth discharge is possible.

By the coating method using this water-based anticorrosive coating composition, coating is performed with a dry coating thickness of 125 μm as a guideline. However, due to the nature of the coating method, a wrap portion is formed, and about 250 μm, which is twice the guideline, may deposit. Even in such a case, the paint of the present invention has no sagging and no cracks are generated in the dried coating film. In addition, good adhesion to the steel sheet can be obtained by the conventional ground treatment method (Sa2.5).
Furthermore, the water-based anticorrosive coating composition of the present invention can be used as a top coat.
Moreover, the steel plate with an anticorrosion coating film of the present invention exhibits excellent anticorrosion properties over a long period of time.

Hereinafter, the water-based anticorrosive coating composition and the steel plate with the anticorrosive coating film according to the present invention will be specifically described.
The water-based anticorrosive coating composition according to the present invention comprises a reaction liquid (a) obtained by reaction of a polyisocyanate compound having a hydrophilic site and a secondary amino group-containing alkoxysilane, a zinc-containing powder (b), a thixotropic agent ( c), and water (d).
Hereinafter, each component will be described.

The reaction liquid (a) used in the present invention is obtained by a reaction between a polyisocyanate compound having a hydrophilic site and a secondary amino group-containing alkoxysilane. The reaction product produced by the reaction contained in the reaction liquid (a) functions as a binder. Since the reaction product contained in the reaction liquid (a) has a hydrophilic portion, the reaction product is converted into emulsion particles having an average particle diameter of 50 μm to 300 μm by dispersing the reaction liquid (a) in water. I can do it. At this time, the terminal alkoxy group of the reaction product is expected to be inside the emulsion particle, and contact between the terminal alkoxy group and the water molecule is avoided, so that the emulsion particle exists stably in water for several hours. Can do. A compound that is stably dispersed is a compound that remains in a mixed state with water as an oil-in-water emulsion or a water-in-oil emulsion without precipitation, coagulation or separation for a sufficient time to use the dispersion for the intended purpose. is there.
Moreover, it is desirable that the hydrophilic portion in the polyisocyanate compound is composed of an ethylene oxide chain or a sulfonic acid salt from the viewpoint of water dispersibility.

  Moreover, when the water-based anticorrosive coating composition of the present invention becomes a zinc coating film, silanol groups generated by hydrolysis of terminal alkoxysilanes of the reaction product contained in the reaction liquid (a) are present. It produces a strong bond between the coating and the steel plate. Furthermore, the silanol group is bonded to the zinc-containing powder, so that the coating film becomes strong. Furthermore, the presence of an organic group in the reaction product contained in the reaction liquid (a) allows the zinc coating film formed from the aqueous anticorrosive coating composition of the present invention to be more flexible than a general inorganic zinc coating film. When a thick film is used, good crack resistance is exhibited.

This coating film has an anticorrosive action peculiar to a zinc-containing coating film. When the film is thick, it can provide anticorrosion properties to the steel sheet for a long period of time, and has a sacrificial anticorrosive action to the damaged portion.
The reaction product contained in the reaction liquid (a) is synthesized by combining the NCO of the polyisocyanate compound and the secondary amino group of the aminosilane compound. The reaction of NCO and amino group is carried out at a temperature of 10 to 100 ° C., preferably 20 to 80 ° C., more preferably 20 to 50 ° C. for 1 to 5 hours, preferably 1 to 3 hours.

  Examples of the secondary amino group-containing alkoxysilane include a compound represented by Formula I and a compound represented by Formula II. As the secondary amino group-containing alkoxysilane, either one or both of the compound represented by Formula I and the compound represented by Formula II can be used.

式Ｉ中、３個のＸはそれぞれ有機基を表す。３個のＸはそれぞれ異なる有機基であってもよく、２個または３個のＸが同一の有機基であってもよい。

In formula I, three Xs each represent an organic group. Three Xs may be different organic groups, and two or three Xs may be the same organic group.

Examples of the organic group include an alkoxy group, an alkyl group, an alkenyl group, and an arylalkyl group. At least one of X is an alkoxy group.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. As the alkoxy group, a methoxy group, an ethoxy group, and a propoxy group are preferable because raw materials are easily available.

Examples of the alkyl group include an alkyl group having 20 or less carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, and the like.
Examples of the alkenyl group include a vinyl group, a propenyl group, and a butenyl group.

Examples of the arylalkyl group include a benzyl group, a phenethyl group, and a phenylpropyl group.
In Formula I, R ₁ represents a linear or branched alkyl group having 1 to 8 carbon atoms or a phenyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. The alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group.

In the formula I, n is an integer of 1 to 8, preferably an integer of 2 to 4.
Specific examples of the compound represented by the formula I include (N-cyclohexylaminomethyl) methyldiethoxysilane, (N-cyclohexylaminomethyl) triethoxysilane, (N-phenylaminomethyl) methyldimethoxysilane, (N Examples include silane coupling agents such as -phenylaminomethyl) trimethyloxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and 3- (n-butylamino) propyltrimethoxysilane.

式ＩＩ中、３個のＸはそれぞれ有機基を表し、Ｘの少なくとも１個はアルコキシ基であり、ｎは１〜８の整数である。Ｘおよびｎについては、式ＩにおけるＸおよびｎとそれぞれ同様である。

In formula II, three Xs each represent an organic group, at least one of X is an alkoxy group, and n is an integer of 1-8. X and n are the same as X and n in Formula I, respectively.

  Specific examples of the compound represented by Formula II include silane coupling agents such as bistriethoxysilylpropylamine, bismethoxydimethoxysilylpropylamine, and bisethoxydiethoxysilylpropylamine.

  The silicon-containing group in the aminosilane compound represented by the above formula I or formula II has 1 to 3 hydrolyzable alkoxy groups bonded to a silicon atom, and is necessary in the presence of moisture or a crosslinking agent. Accordingly, by using a catalyst or the like, a condensation reaction can be caused to form a siloxane bond, which can be crosslinked, thereby contributing to the curing reaction of the paint. Specifically, as the silicon-containing group, an alkoxysilyl group, an alkenyloxysilyl group, an acyloxysilyl group, an aminosilyl group, an aminooxysilyl group, an oximesilyl group, an amidosilyl group and the like are preferably used.

  As a commercial item of a polyisocyanate compound having a hydrophilic portion, for example, Basonat HW-100 manufactured by BASF can be mentioned as a polyisocyanate obtained by modifying 1,6-hexamethylene diisocyanate that has been isocyanurated with an ether emulsifier.

The polyisocyanate compound having a hydrophilic site can be obtained by reacting a hydrophilic compound with a polyisocyanate compound in addition to the above-mentioned commercially available products.
For example, the polyisocyanate compound having the above-mentioned hydrophilic portion can be obtained by reacting polyethylene glycol or polyol with an excess amount of polyisocyanate in the presence of a urethanization catalyst.

  Usable hydrophilic compounds are compounds containing side chain or terminal hydrophilic ethylene oxide units and / or compounds containing ionic or latent ionic groups. The ionic group or latent ionic group may be an anionic group or a cationic group, but an anionic group is preferred. Examples of anionic groups include carboxylate groups and examples of cationic groups include ammonium groups and sulfonium groups.

  A polyisocyanate compound is a compound having an average of two or more isocyanate groups in one molecule, and such a compound can be used for synthesis of a binder component without limitation. Further, the polyisocyanate compound may react with other compounds to form an adduct within a range where the average number of isocyanate groups in one molecule is 2 or more.

  Specific examples of such polyisocyanate compounds include MDI such as 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, and H12MDI; Crude MDI; 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and the like. TDI of naphthalene-1,5-diisocyanate (NDI), tolidine diisocyanate (TODI), xylylene diisocyanate (XDI), H6 XDI (HXDI), p-phenylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), triphenylmethane Triisocyanate, toluene diisocyanate, 1,3-bis- (1-isocyanate-1-methylethyl) -benzene, 1,4-bis- (1-isocyanate-1-me Ruethyl) -benzene, 1,3-bis- (1-isocyanatomethyl) -benzene, 1,5-dimethyl-2,4-bis- (isocyanate-methyl) -benzene, 1,5-dimethyl-2,4 -Bis- (isocyanatoethyl) -benzene, 1,3,5-triethyl-2,4-bis- (isocyanatomethyl) -benzene, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, etc. Aromatic diisocyanates: ethylene diisocyanate, propylene diisocyanate, 2,3-butylene diisocyanate, hexamethylene diisocyanate (HDI), octamethylene diisocyanate, dodecamethylene diisocyanate, ω, ω'-dipropyl ether diisocyanate, lysine diisocyanate (LDI) , Trimethyl hexame Aliphatic polyisocyanates such as diisocyanate (TMDI); isophorone diisocyanate (IPDI), cyclopentene diisocyanate, cyclohexane diisocyanate, transcyclohexane-1,4-diisocyanate, 4-methyl-1,3-diisocyanatocyclohexane, dicyclohexylmethane 4,4'-diisocyanate, 3,3'-dimethyl-dicyclohexylmethane-4,4'-diisocyanate alicyclic polyisocyanate; norbornane skeleton diisocyanate (NBDI), and the like. Moreover, the polymer which can be manufactured from the polyisocyanate compound illustrated above can also be used as a polyisocyanate compound.

  Among these polyisocyanate compounds, MDI, crude MDI, TDI, XDI, TMXDI, IPDI, NBDI, HXDI, HDI and polymers thereof are preferable. This is because these isocyanate compounds and polymers are industrially produced in a relatively large amount, so that they are inexpensive and easily available, and have good reactivity with aminosilane compounds. More preferred are HDI, XDI, IPDI, NBDI and polymers thereof.

  From the viewpoint of corrosion resistance, it is preferable that the reaction product contained in the reaction solution (a) has a high NCO group modification ratio and a large number of alkoxy groups. However, the secondary amino group-containing alkoxysilane used for introducing the alkoxy group is insoluble in water and unstable in water. Therefore, when the polyisocyanate compound reacts with the secondary amino group-containing alkoxysilane, the equivalent ratio (NCO / NH) of the isocyanate group (NCO) of the polyisocyanate compound to the secondary amino group of the secondary amino group-containing alkoxysilane is , 1.0 / 0.8 to 1.0 / 1.0, preferably 1.0 / 0.95 to 1.0 / 1.0.

  When the equivalent ratio is out of this range and the isocyanate becomes excessive, the coating film formed from the water-based anticorrosive coating composition containing the reaction liquid (a) is insufficient in anticorrosive properties. On the other hand, when the equivalence ratio is outside this range and the amine is excessive, an unreacted aminosilane compound remains, so that even if the reaction solution (a) is used for coating, it is difficult to obtain a uniform aqueous anticorrosive coating composition.

  The zinc-containing powder (b) is used as an anticorrosive pigment for preventing rusting of the steel sheet in the coating film formed from the aqueous anticorrosive coating composition of the present invention. As this zinc containing powder (b), what is normally used for the water-system anticorrosion coating composition can be used, and zinc powder with an average particle diameter of 2 micrometers-15 micrometers is preferable. Further, the zinc-containing powder (b) of the present invention includes a zinc alloy powder. Examples of zinc alloys include conventionally known Zn—Ni, Zn—Sn, Zn—Fe, Zn—Al, Zn—Al—Mg, and the like.

  In addition to the spherical shape, the zinc-containing powder (b) may be a flat zinc powder for the purpose of preventing water from penetrating into the coating film (barrier effect). Examples of the flat zinc powder include STANDART Zinc flake GTT manufactured by ECKART.

  Examples of the thixotropic agent (c) include bentonite compound thixotropic agents that can be swollen with water. For example, trade name “Benton EW”, trade name “Benton DE”, trade name “Benton HD”, trade name “Benton LT” manufactured by Elementis), trade name “Laponite RD”, trade name “Laponite RDS” ( Rock Wood Additives).

  Examples of the thixotropic agent (c) include a liquid thixotropic agent. Examples of liquid thixotropic agents include “BYK-420 (modified urea), BYK-425 (urea modified urethane), BYK-428 (polyurethane)” (each trade name, manufactured by BYK), “ER-3 (polyether polyurethane). ), ER-90 (polyether polyurethane) ”(each trade name, manufactured by Ito Oil Co., Ltd.),“ Tixol K-130B (polycarboxylic acid), Tixol K-502 (polycarboxylic acid), Tixol W-300 (fatty acid polyamide) ), Tixol W-400LP (fatty acid polyamide / polyethylene oxide) "(each trade name, manufactured by Kyoeisha Chemical Co., Ltd.)," AQ-580 (polyamide amine salt), AQ-600 (polyamide amine salt), AQ-607 ( Polyamide amine salt), AQ-610 (polyamide amine salt), AQ-630 (polyamide) Min salt), AQ-870 (polyamide amine salt) ”(each trade name, manufactured by Enomoto Kasei Co., Ltd.),“ Senka Act Gel AP200 (polyacrylic acid salt type), Senka Act Gel NS100 (polyacrylamide type), Senka Act Gel CM100 (polymethacrylic acid ester) ”(each trade name, manufactured by Senca),“ SN thickener 601 (polyether type), SN thickener 613 (modified polyacrylic acid type), SN thickener 615 (modified polyacrylic sulfone) Acid salt), “SN thickener 618 (modified polyacrylic acid sodium), SN thickener 621N (urethane modified polyether type), SN thickener 630 (modified polyacrylic type), SN thickener 634 (modified polyacrylic type), SN thickener 636 (Modified polyacrylic), SN thickener 4 050 (inorganic silica type) "(each trade name, manufactured by San Nopco).

When coating a coating composition containing a high density powder such as zinc-containing powder at a high concentration on a thick film of about 250 μm with a coating machine with a high discharge rate, such as an airless coating machine, while maintaining workability In order to prevent the problem of sagging, the thixotropy of the coating composition becomes very important. The bentonite compound thixotropic agents (powder) listed here swell with water and give moderate thixotropy to the paint to prevent sagging during painting. It has the effect of preventing pigment settling. Similarly, the liquid thixotropic agent as described above also has an effect of preventing sagging during coating and preventing sedimentation of zinc-containing powder and other pigments in the coating composition.
As the water (d), ion exchange water, tap water and the like can be used.

  In addition, a pigment for filling may be added to the water-based anticorrosive coating composition of the present invention. Examples of the filler pigment include talc, mica, and wollastonite, which are flat, flake shaped, or acicular pigments. These are pigments having a relatively large oil absorption, can impart viscosity to the coating composition, and can reduce sagging of the coating composition. Furthermore, mica, wollastonite, etc. give strength to the coating film. Moreover, talc can relieve the internal stress of the coating film and prevent the coating film from cracking.

  Further, potassium feldspar, silica powder, precipitated barium sulfate, titanium oxide, calcium carbonate, aluminum hydroxide, carbon black, alumina and the like may be added to the water-based anticorrosive coating composition of the present invention.

Titanium oxide, zinc oxide, iron oxide or the like may be added as a coloring pigment to the water-based anticorrosive coating composition of the present invention.
In addition, whiskers such as basic magnesium sulfate, potassium titanate, sepiolite, and zonotlite can be added to the water-based anticorrosive coating composition of the present invention in order to improve crack resistance.
The water-based anticorrosive coating composition of the present invention may contain a pigment dispersant.

  Usually, since the binder component has a high viscosity and may have a handling problem, an organic solvent can be added to the water-based anticorrosive coating composition of the present invention. Examples of organic solvents include various commonly used solvents such as alcohols, glycols, esters, ketones, aromatics, and glycols.

  Examples of the alcohol solvent include methanol, ethanol, isopropanol, butanol, 2-butanol, ter-butanol, and the like. However, the alcoholic solvent is added after the NCO of the polyisocyanate compound and the secondary amino group of the secondary amino group-containing alkoxysilane are sufficiently reacted, considering that it reacts with the NCO of the starting isocyanate compound.

  Examples of ester solvents include ethyl acetate, butyl acetate, propylene carbonate (PC), and examples of ketone solvents include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and N-methylpyrrolidone. Examples of the aromatic solvent include benzene, xylene, and toluene. Examples of the glycol solvent include propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate (PGMAC), ethylene, and the like. Examples thereof include diglycol acetate (EDGAC) and ethylene glycol monobutyl ether (butyl cellosolve). These solvents are used alone or in combination of two or more.

  In the water-based anticorrosive coating composition of the present invention, the component (a) is 1 to 20% by weight, preferably 1 to 10% by weight, the component (b) is 20 to 90% by weight, preferably 40 to 90% by weight, the component ( It is desirable that c) is contained in an amount of 0.1 to 10% by weight, preferably 0.1 to 2% by weight, and water (d) is contained in an amount of 1 to 20% by weight, preferably 1 to 10% by weight.

  Further, the filler pigment used as required is usually contained in an amount of 10 to 40% by weight, preferably 15 to 25% by weight, and the color pigment is usually contained in an amount of 1 to 15% by weight, preferably 3 to 10% by weight. The

  The water-based anticorrosive coating composition of the present invention comprising the above components is usually used as a three-pack type, and pack A containing the reaction liquid (a) and pack B containing the zinc-containing powder (b). The pack C containing the thixotropic agent (c) and water (d) is preferably stored in a separate container and mixed immediately before use.

The pack A may contain the reaction solution (a), but is preferably prepared by adding a small amount of an organic solvent to the reaction solution (a) in order to improve the film forming property.
On the other hand, the pack B may contain the zinc-containing powder (b), and if necessary, the pack B is prepared by mixing the filler pigment, whiskers with anti-cracking properties, color pigments and the like.

  Pack C may contain thixotropic agent (c) and water (d), and is prepared, for example, by mixing an aqueous bentonite compound or liquid modifier, a pigment dispersant, and ion-exchanged water. Is done.

The water-based anticorrosive coating composition obtained by blending the above materials is applied to a base material such as a steel plate that has been sufficiently ground-treated, or a base material such as a steel plate that has been coated with a general inorganic zinc shop primer. Painted directly.
Painting can be performed using an airless spray coater.

<Base material with anticorrosion coating>
The base material with an anticorrosion coating film according to the present invention has an anticorrosion coating film formed from an aqueous anticorrosion coating composition on the surface of a base material such as a steel plate. Such a substrate with an anticorrosive coating can be prepared according to a conventional method. For example, the water-based anticorrosive coating composition of the present invention is applied to the substrate surface by air spray, airless spray or the like and dried at room temperature.

  The water-based anticorrosive coating composition of the present invention can be thickly coated so that the average dry film thickness of the anticorrosive coating film after drying formed from the anticorrosive coating composition is 250 to 300 μm. Furthermore, since the anticorrosion coating film formed from the water-based anticorrosion coating composition of the present invention does not have defects such as sagging, swelling, and cracks, it can exhibit excellent anticorrosion properties over a long period of time.

≪Base material anticorrosion method≫
The anticorrosion method for the substrate of the present invention is not particularly limited as long as it includes the step of applying the composition of the present invention on the substrate, but the coating film is formed by applying the composition of the present invention on the substrate. A method of preventing corrosion of the substrate by forming the coating film and drying and curing the coating film is preferable.

In this method, the base material, the coating method, and the like may be the same as those described in the column of the base material with the anticorrosion coating film.
In the anticorrosion method for the base material, a conventionally known top coat such as an antifouling paint may be applied on the obtained coating or anticorrosion coating, and dried and cured, depending on the desired application. Good.
For example, the anti-corrosion method for the ballast tank is performed as follows.

  First, the composition of the present invention is spray-coated on the ballast tank (the first coating), and after the coating film has dried, a stripe coat is applied to the weld line and edge portion where it is difficult to ensure the film thickness with a brush or roller. The composition is spray-coated again (second coating) to form an anticorrosion coating film having a thickness of about 320 μm.

  This type of anti-corrosion method for ballast tanks requires a brush or roller stripe coating, which requires not only spray work but also paint work with the brush and roller. The coated film is required to be formed in a healthy state free from bubbles and pinholes.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
[Production Example 1]
Water-dispersed isocyanate compound under a nitrogen atmosphere (Basonat HW-100 manufactured by BASF: polyisocyanate modified with isocyanurated 1,6-hexamethylene diisocyanate with an ether emulsifier, NCO content: 17 ± 0.5% ) 156 g and 78 g of MEK as a solvent were introduced into a container and heated until the internal temperature reached 60 ° C. Thereafter, 151.32 g of the aminosilane compound 3- (n-butylamino) propyltrimethoxysilane (manufactured by Dynasilan 1189 Evonik Degussa) was dropped into the container using a dropping funnel. The equivalent ratio (NCO / NH) (hereinafter referred to as equivalent ratio) of the isocyanate group (NCO) of the polyisocyanate compound to the secondary amino group of the secondary amino group-containing alkoxysilane was 1.0 / 1.0.

At this time, the internal temperature was made not to exceed 75 ° C. After all the aminosilane compound was dropped, stirring was continued for 2 hours while maintaining the temperature of the oil bath at 60 ° C. After confirming that an isocyanate group was not detected by IR spectroscopy, the mixture was cooled to room temperature, 39 g of MEK and 39 g of ethanol were added to the container, and the liquid was drained.
Thus, the reaction liquid (a1) containing the reaction product of a polyisocyanate compound and a secondary amino group containing alkoxysilane was obtained.

[Production Example 2]
Water-dispersed isocyanate compound under a nitrogen atmosphere (Basonat HW-100 manufactured by BASF: polyisocyanate modified with isocyanurated 1,6-hexamethylene diisocyanate with an ether emulsifier, NCO content: 17 ± 0.5% ) 156 g and 78 g of MEK as a solvent were introduced into a container and heated until the internal temperature reached 60 ° C. Then, using a dropping funnel, 75.7 g of aminosilane compound 3- (n-butylamino) propyltrimethoxysilane (manufactured by Dynasilan 1189 Evonik Degussa) and bistriethoxysilylpropylamine (manufactured by Dynasilan 1124 Evonik Degussa) 109. 8 g of the mixture was dropped into the container. The equivalent ratio was 1.0 / 1.0.

At this time, the internal temperature was made not to exceed 75 ° C. After all the aminosilane compound was dropped, stirring was continued for 2 hours while maintaining the temperature of the oil bath at 60 ° C. After confirming that an isocyanate group was not detected by IR spectroscopy, the mixture was cooled to room temperature, 49 g of MEK and 49 g of ethanol were added to the container, and the liquid was drained.
Thus, the reaction liquid (a2) containing the reaction product of a polyisocyanate compound and a secondary amino group containing alkoxysilane was obtained.

[Production Example 3]
Water-dispersed isocyanate compound under a nitrogen atmosphere (Basonat HW-100 manufactured by BASF: polyisocyanate modified with isocyanurated 1,6-hexamethylene diisocyanate with an ether emulsifier, NCO content: 17 ± 0.5% ) 156 g and 78 g of MEK as a solvent were introduced into a container and heated until the internal temperature reached 60 ° C. Thereafter, using a dropping funnel, 143.75 g of an aminosilane compound 3- (n-butylamino) propyltrimethoxysilane (manufactured by Dynasilan 1189 Evonik Degussa) was dropped into the container. The equivalent ratio was 1.0 / 0.95.

At this time, the internal temperature was made not to exceed 75 ° C. After all the aminosilane compound was dropped, stirring was continued for 2 hours while maintaining the temperature of the oil bath at 60 ° C. After cooling to room temperature, 38.2 g of MEK and 38.2 g of ethanol were added to the container, and the liquid was drained.
Thus, the reaction liquid (a3) containing the reaction product of a polyisocyanate compound and a secondary amino group-containing alkoxysilane was obtained.

[Production Example 4]
Water-dispersed isocyanate compound under a nitrogen atmosphere (Basonat HW-100 manufactured by BASF: polyisocyanate modified with isocyanurated 1,6-hexamethylene diisocyanate with an ether emulsifier, NCO content: 17 ± 0.5% ) 156 g and 78 g of MEK as a solvent were introduced into a container and heated until the internal temperature reached 60 ° C. Thereafter, 113.49 g of an aminosilane compound 3- (n-butylamino) propyltrimethoxysilane (manufactured by Dynasilan 1189 Evonik Degussa) was dropped into the container using a dropping funnel. The equivalent ratio was 1.0 / 0.75.

At this time, the internal temperature was made not to exceed 75 ° C. After all the aminosilane compound was dropped, stirring was continued for 2 hours while maintaining the temperature of the oil bath at 60 ° C. After cooling to room temperature, 30.4 g of MEK and 30.4 g of ethanol were added to the container, and the liquid was drained.
Thus, the reaction liquid (a'1) containing the reaction product of a polyisocyanate compound and a secondary amino group containing alkoxysilane was obtained.

[Production Example 5]
Water-dispersed isocyanate compound under a nitrogen atmosphere (Basonat HW-100 manufactured by BASF: polyisocyanate modified with isocyanurated 1,6-hexamethylene diisocyanate with an ether emulsifier, NCO content: 17 ± 0.5% ) 156 g and 78 g of MEK as a solvent were introduced into a container and heated until the internal temperature reached 60 ° C. Thereafter, using a dropping funnel, 75.7 g of an aminosilane compound, 3- (n-butylamino) propyltrimethoxysilane (manufactured by Dynasilan 1189 Evonik Degussa) was dropped into the container. The equivalent ratio was 1.0 / 0.5.

At this time, the internal temperature was made not to exceed 75 ° C. After all the aminosilane compound was dropped, stirring was continued for 2 hours while maintaining the temperature of the oil bath at 60 ° C. After cooling to room temperature, 20.7 g of MEK and 20.7 g of ethanol were added to the container, and the liquid was drained.
Thus, the reaction liquid (a'2) containing the reaction product of a polyisocyanate compound and a secondary amino group containing alkoxysilane was obtained.

[Production Example 6]
Water-dispersed isocyanate compound under a nitrogen atmosphere (Basonat HW-100 manufactured by BASF: polyisocyanate modified with isocyanurated 1,6-hexamethylene diisocyanate with an ether emulsifier, NCO content: 17 ± 0.5% ) 132 g and 68 g of solvent MEK were introduced into a container, and the mixture was sufficiently stirred at room temperature to drain the solution.
In this way, a mixture of the solvent and the water-dispersed isocyanate compound was obtained.

<Preparation of Pack A>
According to Table 1 and Table 2, each component of Pack A was put into a round can whose inner surface was coated with a rust preventive coating, and thoroughly stirred and mixed with a disper to prepare Pack A. In addition, in the column of packs A to C in Table 1 and Table 2, the numerical values without the unit notation represent parts by mass.

<Preparation of Pack B>
In accordance with Tables 1 and 2, put zinc powder (Umicore Malaysia Sdn Bhd, average particle size 3.7-4.5 μm), potassium feldspar (Sibelco Malaysia Sdn Bhd, particle size 325 mesh) into the container, and enough And pack B was prepared.

<Preparation of Pack C>
For pack C used in Examples 1 to 3 and Comparative Examples 1 to 4, according to Table 1, ion exchange water is placed in a round can whose inner surface is coated with antirust, and a pigment dispersant ( Additol VXW 6208) was added and stirred with a disper. Thereafter, Benton EW and Laponite RD were gradually added while stirring, and after the addition was completed, the mixture was stirred for 20 minutes to prepare Pack C.

  For pack C used in Examples 4 to 8, according to Table 2, ion exchange water is added to a round can whose inner surface is coated with rust prevention, a pigment dispersant (Additol VXW 6208) is added, And stirred. Thereafter, the thixotropic agent was gradually added while stirring was continued, and after the addition was completed, the mixture was stirred for 20 minutes to prepare Pack C.

[Examples 1-8, Comparative Examples 1-5]
Pack A, Pack B and Pack C were sufficiently mixed at the mixing ratios shown in Tables 1 and 2 to obtain aqueous anticorrosive coating compositions of Examples 1 to 8 and Comparative Examples 1 to 4.
As the water-based anticorrosive coating composition of Comparative Example 5, Galbon L (trade name, manufactured by China Paint Co., Ltd., water-based inorganic zinc paint using water-based alkali silicate as a binder) was used.
In Examples 1 to 3 and Comparative Examples 1 to 3, the following initial physical property evaluation, anticorrosion test, crack resistance test and sagging test were performed. In Examples 4 to 8, a sagging property test was performed. The results are shown in Tables 1 and 2.

(1) Evaluation of initial physical properties
(A) Test method and evaluation standard of coating film appearance Sandblasted steel plate (70 mm × 150 mm × 3.2 mm (thickness), manufactured by TP Giken Co., Ltd.) (hereinafter also referred to as “substrate 1”), heat-resistant inorganic zinc on the sandblasted steel plate The shop primer “Cerabond 2000 (trade name), manufactured by China Paint Co., Ltd.” is applied so that the DFT (dry coating thickness) is 15 μm, and is allowed to dry for more than a week (14 days) in an outdoor exposure state. Two types of test piece base materials were prepared: an obtained steel sheet with an undercoat (shop primer) (hereinafter also referred to as a substrate 2).

The test liquid obtained by diluting by adding ion exchange water at a ratio of 7 parts by mass to 100 parts by mass of the water-based anticorrosive coating composition is applied to the substrate 1 by air spray so that the dry film thickness is about 150 μm. And dried at room temperature (20 ° C.) for 7 days to obtain a test piece. For Example 1, the same operation as described above was performed on the substrate 2 to obtain a test piece.
The appearance of the coating film of this test piece was visually observed and evaluated according to the following criteria.
<Evaluation criteria>
4: Smooth and uniform coating.
3: It is not smooth, and it has a uniform coating, although it can be seen in the skin.
2: A coating film that is not smooth and uniform and has slight cracks and repellency.
1: A coating film that is not smooth and uniform, and clearly shows cracking and repellency abnormalities.

(B) [Adhesion]
(A) Cross-cut test method and evaluation criteria A cross-cut test was carried out using the above test piece in accordance with the "cross cut tape method" of "JIS K-5400 8.5.2". 25 squares having a width of 3 mm were prepared, the number of residual squares in the adhesion test was measured, and adhesion was evaluated according to the following criteria.
<Evaluation criteria> (cross-cut test)
4: Each cut is thin and both ends are smooth, the intersection of the cut and the square are not peeled off at a glance, and the area of the defect is less than 5% of the total square area.
3: There is peeling at both sides of the cut and at the intersection, and the area of the defect is 5% or more and less than 15% of the total square area.
2: The width of the peeling of the cut is wide, and the area of the defect is 15% or more and less than 35% of the total square area.
1: The width of peeling of the cut is wider than the width of “Evaluation: 2”, and the area of the defect portion is 35% or more of the total square area.

(B) Test Method and Evaluation Criteria for Knife Test Using the above test piece, a knife test was carried out according to the “X cut tape method” of “JIS K-5400 8.5.3”. Adhesion was evaluated according to the following criteria.
<Evaluation criteria> (Knife test)
4: No peeling at all.
3: There is no peeling at the intersection, and there is a slight peeling at the X-cut portion.
2: There is peeling within 3 mm in any direction from the intersection of the X cut portions.
1: Most of the X-cut portion where the tape is applied is peeled off.

(2) Anticorrosion test A test piece was prepared in the same manner as in the evaluation of the initial physical properties.
(I) Salt water immersion (salt water resistance) test method and evaluation criteria A salt water resistance test was performed in accordance with "JIS K 5400 8.23" using the above test pieces. Immersion was performed for 3 months in 40 ° C. artificial seawater (Aquamarine). The corrosion resistance was evaluated from the appearance and rusting according to the following criteria.

In addition, an adhesion test (cross-cut test) was conducted in accordance with the “cross-cut tape method” of “JIS K-5400 8.5.2” using the above-mentioned test pieces after the appearance and rust tests. went. 25 squares having a width of 3 mm were prepared, the number of residual squares in the adhesion test was measured, and the anticorrosion properties were evaluated from the crosscut test according to the following criteria.
<Evaluation criteria> (Appearance)
4: The coating film does not swell and peel off, and the coating film does not dissolve or collapse.
3: The coating film does not swell and peel off, but the coating film is slightly dissolved or disintegrated.
2: Swelling and peeling of the coating film, and some dissolution and disintegration of the coating film are observed.
1: Swelling and peeling of the coating film, and dissolution and disintegration of the coating film are often observed.
<Evaluation criteria> (rusting)
4: There is no red rust from the base material and no white rust from the zinc 3: There is no red rust from the base material, but there is much white rust from the zinc 2: Red rust is generated from the base material , Many occurrences of white rust from zinc 1: Many occurrences of red rust from base material, many occurrences of white rust from zinc <Evaluation criteria> (cross-cut test)
4: Each cut is thin and both ends are smooth, the intersection of the cut and the square are not peeled off at a glance, and the area of the defect is less than 5% of the total square area.
3: There is peeling at both sides of the cut and at the intersection, and the area of the defect is 5% or more and less than 15% of the total square area.
2: The width of the peeling of the cut is wide, and the area of the defect is 15% or more and less than 35% of the total square area.
1: The width of peeling of the cut is wider than the width of “Evaluation: 2”, and the area of the defect portion is 35% or more of the total square area.

(B) Salt Spray Test Method and Evaluation Criteria Using the above test piece, a salt spray test was performed in accordance with “JIS K-5600 7.1”. Immersion was performed for 2000 hours in 35% 5% salt water. Corrosion resistance was evaluated according to the evaluation criteria of the salt water resistance test method.

(C) Constant temperature and humidity test method and evaluation criteria A constant temperature and humidity test was performed in accordance with "JIS K-5600 7.2" using the above test piece. The test conditions were 50 ° C. and 95% RH or more for 3 months. Corrosion resistance was evaluated according to the evaluation criteria of the salt water resistance test method.

(3) Test method and evaluation criteria for crack resistance of coating film A plurality of sandblasted steel plates (length 70 mm, width 150 mm, thickness 3.2 mm, manufactured by TP Giken Co., Ltd.) were prepared. Ion exchange at a ratio of 7 parts by mass with respect to 100 parts by mass of the water-based anticorrosive coating composition so that each sandblasted steel sheet has a DFT (dry coating thickness) of 75 μm, 150 μm, 225 μm, 300 μm, 375 μm, or 450 μm. A test solution obtained by diluting with water was applied. The steel sheet on which the coating film was formed was dried indoors at 23 ° C. and 50% relative humidity for 1 week to prepare a test piece. For Example 1, heat-resistant inorganic zinc shop primer “Cerabond 2000 (trade name), manufactured by China Paint Co., Ltd.” was applied to the sandblasted steel sheet so that the DFT (dry coating thickness) was 15 μm, and the outdoor The same operation as described above was performed on a steel sheet with an undercoat (shop primer) obtained by drying in an exposed state for 1 week or longer (14 days) to prepare a test piece. The crack of the coating film of each test piece was observed visually, and the crack resistance of the coating film was evaluated according to the following criteria.
<Evaluation criteria>
2: Cracks are not seen in the coating film.
1: Cracks are observed in the coating film.

(4) Sagging test method and evaluation criteria A plurality of sandblasted steel plates (length 70 mm, width 150 mm, thickness 3.2 mm, manufactured by TP Giken Co., Ltd.) were prepared. Each sandblasted steel plate is set up vertically, and the DFT (dry coating thickness) is set to 100 μm, 150 μm, 200 μm, 250 μm, or 300 μm on each sandblasted steel plate, with respect to 100 parts by mass of the water-based anticorrosive coating composition. The test liquid obtained by adding ion-exchanged water at a ratio of 5 parts by weight and diluting was coated using an airless coating machine. The steel sheet on which the coating film was formed was dried indoors at 23 ° C. and a relative humidity of 50% for 1 day to prepare a test piece. For Example 1, heat-resistant inorganic zinc shop primer “Cerabond 2000 (trade name), manufactured by China Paint Co., Ltd.” was applied to the sandblasted steel sheet so that the DFT (dry coating thickness) was 15 μm, and the outdoor The same operation as described above was performed on a steel sheet with an undercoat (shop primer) obtained by drying in an exposed state for 1 week or longer (14 days) to prepare a test piece. The state of the coating film of each test piece was visually observed, and the sagging property of the coating film was evaluated according to the following criteria.
<Evaluation criteria>
3: No sagging is seen in the coating film.
2: A slight sagging is seen in the coating film.
1: Sagging is clearly seen in the coating film.

  In Comparative Example 4, the polyisocyanate compound and aminosilane used in the binder synthesis in Production Example 1 were used as they were without being reacted in advance to form a paint. That is, Comparative Example 4 is a cold blend of raw materials for the binder resin.

  However, since the aminosilane is insoluble in water, this paint requires constant stirring at the time of painting in order to maintain the uniformity of the paint, and the usable life of the paint is also short. I couldn't. In other words, this paint was not practical. From this, it is understood that the polyisocyanate compound and aminosilane need to be combined before forming a paint.

Claims (7)

A reaction solution (a) obtained by reacting a polyisocyanate compound having a hydrophilic site with a secondary amino group-containing alkoxysilane,
Zinc-containing powder (b),
Thixotropic agent (c),
And water (d)
A water-based anticorrosive coating composition comprising
In the reaction, the equivalent ratio (NCO / NH) of the isocyanate group of the polyisocyanate compound to the secondary amino group of the secondary amino group-containing alkoxysilane is 1.0 / 0.95 to 1.0 / 1.0. An aqueous anticorrosive coating composition. The water-based anticorrosive coating composition according to claim 1, wherein the secondary amino group-containing alkoxysilane is a compound represented by the following formula I and / or a compound represented by the following formula II.

(In the formula, each of three X represents an organic group, at least one of X is an alkoxy group, R ₁ represents a linear or branched alkyl group having 1 to 8 carbon atoms or a phenyl group, n is an integer of 1-8.)

(In the formula, three Xs each represent an organic group, at least one of X is an alkoxy group, and n is an integer of 1 to 8)   The water-based anticorrosive coating composition according to claim 1 or 2, wherein the hydrophilic portion of the polyisocyanate compound is composed of an ethylene oxide chain or a sulfonic acid salt.   The water-system anticorrosive coating composition according to any one of claims 1 to 3, wherein the thixotropic agent (c) is composed of a bentonite compound thixotropic agent and / or a liquid thixotropic agent.   The anticorrosion coating film formed from the water-system anticorrosion coating composition of any one of Claims 1-4.   The base material with an anticorrosion coating film by which the surface of a base material is coat | covered with the anticorrosion coating film formed from the water-system anticorrosion coating composition of any one of Claims 1-4.   The base material anticorrosion method including the process of apply | coating the water-system anticorrosive coating composition of any one of Claims 1-4 on a base material.