JPS61176668A - Water-dispersible coating resin composition having excellent corrosion-proofing property - Google Patents

Abstract

PURPOSE:To provide the titled composition having excellent corrosion-proofing property, by mixing an alkyd resin (derivative) with a corrosion-proofing pigment, and dispersing the mixture in water in the presence of an emulsifier. CONSTITUTION:The objective composition is produced by mixing (A) 100pts.(wt.) of an alkyd resin (derivative) thoroughly with (B) 0.05-20pts. of a corrosion- proofing pigment such as basic lead chromate, and dispersing the mixture in water taking advantage of the hydrophilic group existing in the component A and/or adding (C) an emulsifier to the system. The component A is preferably the one obtained by adding 0-50pts. of an epoxy resin to 100pts. of a raw material consisting of (i) 0-60pts. of a fatty acid, (ii) 5-40pts. of a polyol, (iii) 10-50pts. of a polybasic acid, and (iv) 0-15pts. of a 6-18C monobasic acid, wherein the molar ratio of OH/COOH in the components i-iv is 1.0-2.0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improved water-dispersible resin composition for coating;
More specifically, the present invention relates to a resin composition with excellent rust prevention properties, which is made by adding a specific amount of rust prevention pigment to an alkyd resin or a derivative thereof, thoroughly mixing the mixture, and then dispersing it in water.

[Prior Art and Problems to be Solved by the Invention] Conventionally, various rust-preventing paints have been used for the purpose of coating metal materials to prevent rust.

Most of these are oil-based paints, and the vehicle component is a mixture of alkyd resin, male oil, or natural resin, and components such as coloring pigments, extender pigments, and anti-rust pigments are kneaded into the vehicle component. It is a thing of form.

However, the organic solvents contained in such oil-based paints are not preferable from the viewpoint of resource saving and safety.

Water-based paints are one type of paint that satisfies these needs, and as research has progressed more and more in recent years, they are establishing themselves as resource-saving paints.

By the way, with the progress of recent improvement research, water-based resins are gradually approaching the level of oil-based resins (solvent-based resins) in terms of rust prevention ability, but the essential characteristics of water-based resins are The problem is that the water-based resin, which also serves as the vehicle in the paint, is an emulsifier and has a large amount of hydrophilic groups (R water-based functional groups), so the paint film has high water absorption, which prevents rust from forming and progressing. As a result, water-based paints are generally inferior to oil-based paints in their rust-preventive power.

Recently, although an emulsion for the deaf that does not use an emulsifier has been known in the literature, the stability of the finished log dispersion is poor, and therefore it cannot be said to be of practical use.

On the other hand, although water-soluble resins are superior to emulsions in terms of anti-rust properties, they contain a large amount of water-soluble functional groups such as carboxylic groups and hydroxyl groups to make the 4-limer water-soluble. From this point of view, it can be said that this is also undesirable from the point of view of anti-corrosion ability.

Therefore, various types of rust-preventing pigments are widely used to improve the rust-preventing ability, but since many of these rust-preventing pigments are polyvalent metal salts, for example, amine-neutralized water-soluble pigments are commonly used. In polyvalent resins, so-called metal crosslinks are likely to be formed between carboxyl groups, hydroxyl groups, etc. in the resin and these polyvalent metal ions, and as a result, polymer aggregation is induced. Water-dispersed resin,
For example, in the case of Disno Arms, Nari, and Emulsion K, polyvalent metal ions, which are rust-preventing pigments, tend to crosslink with the hydrophilic groups on the surface of polymer particles and cause polymer aggregation, resulting in poor stability as a paint. It will be inferior,
For this reason, the rust-preventing pigments used in water-based paints are also practically limited, and the reality is that water-based paints are not preferred in terms of improving rust-preventing ability.

By the way, anti-rust pigments are usually mixed with a vehicle as a component of the pigment during the preparation of paints and heated, but for the reasons mentioned above, the finished paints have poor stability), and even worse. During storage of paint, it is easy to cause "water blistering", pigment settling, and color separation, as well as thickening, lubrication, loss of luster of the paint film, and the formation of "debris". The reality is that there are many problems.

[Means for solving problems]

However, the inventors of the present invention have identified various problems and shortcomings in the conventional water-based paints as described above, and as a result of intensive studies in order to solve them, we have developed a method that uses anti-corrosion pigments in advance without using emulsifiers. The anticorrosive pigment is incorporated into the polymer particles by sufficiently mixing it with the resin, and then the hydrophilic groups in the resin are used, or only at this point, an emulsifier is added, and furthermore, the hydrophilic groups are utilized. By dispersing the resin (polymer particles) containing anti-rust pigments in water using both the addition of an emulsifier and the addition of an emulsifier, the stability of the paint can be improved, which is the disadvantage of conventional water-based paints containing anti-rust pigments. The present invention has been completed by discovering a water-dispersible resin composition for coating that has excellent anti-corrosion properties and can be used as a water-dispersible deaf paint that has greatly improved corrosion resistance and excellent corrosion resistance.

That is, the present invention provides a water-dispersible resin composition comprising an alkyd resin or its derivative (A) and a rust-preventing pigment as essential components, and furthermore, 100% by weight of the alkyd resin or its derivative (A). 0.05 to 20 per part
Part by weight of the rust preventive pigment (B) is added and mixed thoroughly, and then the alkyd resin or its derivative (A) is added with a hydrophilic group and/or an emulsifier (C) is added to the water. The present invention provides a water-dispersible resin composition for coating which is dispersed and has excellent anti-rust properties.

The water-dispersible resin composition of the present invention contains an anti-rust pigment inside the polymer particles, and therefore, the conventional method of blending and mixing the anti-rust pigment with a vehicle when preparing a paint is different from the conventional method. In comparison, firstly, it has excellent stability, and the paint obtained using the resin composition of the present invention has excellent rust-preventing power without impairing the inherent ability of the rust-preventing pigment. Here, the alkyd resin (A) described above is not particularly limited as it can be prepared according to any known and commonly used method. a-1
), polyol (a-2), polybasic acid (a-3), and further raw materials such as C6'''018 monobasic acid (a-4> and epoxy resin (a-5)) in a limestone pot. Charge and heat under nitrogen gas atmosphere at 140-300C, preferably 150C.
The condensation is allowed to proceed until the desired acid number is reached at a temperature in the range of ~250°C.

The acid value of the finished resin is 70 or less, preferably 50 or less; if it exceeds 70, the corrosion resistance and water resistance of the coating film will deteriorate, and the rust prevention ability will deteriorate. This is not preferable because the stability of the paint becomes inferior.

Typical raw materials used to prepare the alkyd resin (A) include tung oil, linseed oil, dehydrated castor oil, safflower oil, soybean oil, castor oil, tall oil, rice bran oil, and so-called drying oils, semi-drying oils such as oils, and their fatty acids [hereinafter referred to as oils or fatty acids (a
-1). The polyol (a-2) includes ethylene glycol, propylene glycol, polyethylene glycol or polypropylene glycol having an average molecular weight (Mn) of 400 to 20,000, and diethylene glycol. , diethylene glycol, neopentyl glycol, 1,3-ethylene glycol, 1,4
-butylene glycol, 2.2.4-)dimethyl-1
, 3-bentanediol, 1,6-hexanediol,
Typical examples include cyclohexane dimethylol, dimethylol gropionic acid, glycerin, trimethylolethane, trimethylolethane, tris(2-hydroxyethyl)in cyanurate, (phthaerythritol, dipentaerythritol, etc.). Polybasic acid (a
-3) Typical examples include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hymic acid, maleic acid, fumaric acid, adipic acid, cepacic acid, dimer acid, trimellitic acid/pyro Examples include mellitic acid or their silane anhydrides, and C6~ such as benzoic acid, p-t@rt-butylbenzoic acid, isooctanoic acid, inodecanoic acid, or cyclohexanoic acid.
A monobasic acid (a-4) called Cta can also be used in combination.

Furthermore, "Ebikuron sso, 1oso.

3050.4050 or 7050J (these are 4-4 resins manufactured by Dainippon Ink and Chemicals Co., Ltd.), "Epicoat 828.834.1001.1004.

1007 or 1009J (epoxy resin manufactured by Shell, Netherlands), or rDER660°6
Bisphenol-deaf epoxy resins such as 61J, 662.664J, 667J, 668 or 669JJ (epoxy resins manufactured by Dow Chemical Co., USA), "Evicron 750" or "Yunox 201"
Or an alicyclic epoxy resin such as 289J (epoxy resin manufactured by Union Carbide, USA),
Phenol like "Ebikron N-740 Mojikuha 775" is a rack mold/Φ resin, "Ebiko" 812J
or "Epolite 40K, 200 or 40
Ethylene glycol-based epoxy resin such as 0EJ (epoxy resin manufactured by Kyoeisha Co., Ltd.), or rBF-1
Various epoxy resins (a-5) such as epoxidized polybutadiene such as 000J [Ko I xy resin manufactured by Adeka Argus Chemical Co., Ltd.] can also be used for preparing the alkyd resin derivative (A) by modifying the alkyd resin. In addition, "Suit Mother - Petskasite 1001 or 3011J (all manufactured by Dainippon Ink and Chemicals Co., Ltd.)", "Hital 2181 or 230
Various phenolic resins such as ONJ C or above, manufactured by Hitachi Chemical Co., Ltd.] or ``Nikalua 0PJ (made above, Mitsubishi Gas Chemical Co., Ltd.); Perakasite J-896 or P-720J [made by Dai Nippon Various petroleum resins such as Ink Kagaku Kogyo Co., Ltd. products; rTsR165 or YR3168J;
terminal hydroxyl group-containing silicone resin] or r 5
F8427 or 8428J C or higher, manufactured by Toray Silicone Co., Ltd., silicone resin containing a terminal hydroxyl group], rSF8421J [Silicone resin containing an Epoquine group, manufactured by Toray Silicone Co., Ltd.], or rSF8
Various silicone resins such as 418J (Calgoxy-modified silicone resin manufactured by the same company); furthermore, nitrocellulose, cellulose acetate butyrate, cellulose acetate globionate, cellulose acetate phthalate, acetyl cellulose, cellulose fropionate,
Various cellulose derivatives such as cellulose butyrate, methylcellulose, ethylcellulose, butylcellulose, pennorcellulose, calgoxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose or hydroxyglobil methylcellulose can also be used for modification.

Furthermore, including (meth)acrylic acid esters represented by the general formula, various glycidyl (meth)acrylates, methoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, diethylaminoethyl methacrylate, styrene, α
-methylstyrene, vinyltoluene, vinylpyridine,
! Tadiene, isoprene, chloroprene, (meth)acrylonitrile, or (meth)acrylic acid, itaconic acid, (meth)acrylamide, N-methylacrylamide, N-ethylacrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate,
So-called α,β-ethylenically unsaturated monomers such as water-soluble or hydrophilic monomeric compounds such as acrolein;
, PE350, PME2000.

PME 4000 or Ha80-PMIi: P-4
000J C or higher, polyethylene glycol monomethacrylate manufactured by NOF Corporation)) 1fc is "NK-ester M-90G or M-230GJ C or higher, methoxypreethylene glycol methacrylate manufactured by Shin Nakamura Chemical Co., Ltd. #!" Various kinds of I realkylene glycol (
Meth)acrylate monomeric compounds may also be used for modification.

Therefore, in the present invention, the above-mentioned alkyd resin derivative (A) includes the above-mentioned alkyd resins, and each polar-modified material such as epoxy resin, phenol resin, petroleum resin, silicone resin, cellulose derivative, or acrylic resin. Typical examples include those modified with resins or the various modifying monomeric compounds listed above.

Such modification can impart and further improve adhesion, gloss, drying properties, hardness, flexibility, etc. of the coating film, and can be expected to further improve water dispersibility.

To give an example of such a modification method, in the presence of 10 to 90 parts by weight of the alkyd resin (A), α,β-ethylenically unsaturated monomer (a-6) as described above is added. 70
A method of copolymerizing ~9.5 parts by weight with 20 to 0.5 parts by weight of the above-mentioned polyalkylene glycol (meth)acrylate (a-7) by a conventional method can be mentioned.

The polymerization temperature in this case is suitably within the range of 50 to 180°C, preferably 80 to 150°C, and in such copolymerization, the alkyd resin (A) is dissolved in a water-soluble solvent. It is preferable to start from the beginning because it is easier to control the reaction.

Typical examples of the above solvents that can be used include ethanol, n-7'lononol, 1so-propanol,
3-methoxy-3-methylbutanol, n-butanol, 1so-butanol, aea-butanol, t@rt
-2 tanol, methyl selon, ethyl selon
imo-butylcelonol! ,n-! Terceronulp, methylcarpitol, ethylcarpitol, n-propylcarpitol or n-butylcarpitol, etc., and polymerization initiators such as benzoyl peroxide, azopisinteronitrile% t@rt-butyl hydroxide, Tert-tart-7'' thyl oxide, cumenehyde o-4-oxide or tert-tuterno f-benzoate, etc. can be used.

The oil or fatty acid (a-1) described above is (a-1
) to (a-4) are used in a range of 0 to 60 parts by weight, assuming a total amount of 100 parts by weight (the same applies hereinafter). If the amount exceeds 60 parts by weight, the stability of the resulting aqueous dispersion and, ultimately, the stability of the coating material will deteriorate, which is not preferable.

Next, the polyol (a-2) described above is used in a range of 5 to 40 parts by weight.

Moreover, the polybasic acid (a-3) described above is used in a range of 10 to 50 parts by weight.

Furthermore, the monobasic acid (a-4) 06 to C18 described above
is used in a range of 0 to 15 parts by weight.

Next, each of the above-mentioned modifying resins or each modifying monomeric compound including the above-mentioned epoxy resin (a-5) is added to each of the above-mentioned raw materials (a-1) to (a-4). It is used in a range of 0 to 50 parts by weight based on 100 parts by weight of the total amount.

Among these various modifying resins or various modifying monomeric compounds, when using the epoxy resin (a-5), it is necessary to prepare the alkyd resin (A) from the beginning (
It may be added together with the other raw materials a-1) to (a-4) or during the reaction.

In addition, for example, when using the above-mentioned silicone resin, (a-1) to (a-
4) It is desirable to react together with each of the other raw materials, and when using the cellulose derivatives listed above, it is preferable to mix them directly with the alkyd resin (A) or dissolve them in the water-soluble solvent listed above. Tekarako alkyd resin (A)
Either method may be used, such as mixing with

Note that these various modifying resins or various modifying monomeric compounds may be used alone or in combination of two or more.

In the water-dispersible resin composition of the present invention, 0.05 to 20 parts by weight of the rust preventive pigment (B) is blended with 100 parts by weight of the alkyd resin or its derivative (A) obtained in this way, and the mixture is thoroughly mixed. As the rust preventive pigment (B), any known and commonly used pigment can be used as long as it has rust preventive properties. Representative examples include various chromate compounds such as basic lead chromate, syncchromate, strontium chromate, and barium chromate; various lead-based compounds such as calcium leadate, red lead, and lead cyanamide; Various phosphate compounds such as zinc phosphate, ammonium tripolyphosphate, zinc phosphite; basic zinc molybdate,
Various molybdate-based compounds such as calcium molybdate; various borate-based compounds such as barium metaborate, calcium metaborate, and calcium rosilicate; mica-like iron oxide (MIO), chemical formula M@0Fe203 (however, Me in the formula is Ca h Sr # Ba a Mg
r shall represent a divalent metal atom such as Zn or Mn. ) Various iron oxide compounds such as magnetic ferrite; various basic tungstate compounds such as zinc tungstate and calcium tungstate are represented by the chemical formula ZnRNO2 (wherein R represents an alkyl group The rust-preventive pigment (B) may be used alone or in combination.
Can be used as a mixture of more than one species.

As mentioned above, the appropriate amount of these antirust pigments (B) is within the range of 0.05 to 20 parts by weight, and if it is less than 0.05 parts by weight, the coating film will not be protected. If the amount exceeds 20 parts by weight, the water resistance and moisture resistance of the coating film will become poor, which is not preferable.

The water-dispersible resin composition of the present invention utilizes a hydrophilic functional group, such as a hydrophilic functional group, a cardexyl group, a hydroxyl group, a polyether group, or an amide bond, in the resin containing the anticorrosive pigment obtained in this way. or by adding an emulsifier (C), or by adding an emulsifier (C) at the same time as using the hydrophilic group and dispersing it in water.

When dispersing the resin in water using the hydrophilic groups in the resin, it is necessary to preliminarily prepare a cal. Ammonia: triethylamine, dimethylaminoethanol, morpholine, N-methylmorpholine, 2-amino-2
-Organic amines such as methylpronofnol; or alkali metal hydroxides such as sodium hydroxide and potassium hydroxide may be used for neutralization.

Typical emulsifiers (C) mentioned above include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene lupitor fatty acid ester, ? Lioxyethylene fatty acid ester? Various nonionic or alkyl sulfate salts such as rioxyethylene alcohol ether, glycerin fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene castor oil derivative, polyoxyethylene alkylphenyl ether, alkyl phosphate ester, /lioxyethylene phosphate ester , polyoxyethylene alkyl ether sulfate salts, alkyl sulfosuccinates, N-acyl sarcosine salts, and the like, and these may be used alone or in combination of two or more.

It is desirable to use these emulsifiers by sufficiently mixing them into the resin.

The type and amount of the emulsifier (C) to be used should be determined from the viewpoint of the stability of the dispersed particles and the performance of the coating film, and are not particularly limited in the present invention.

The water-dispersible resin composition of the present invention obtained in this manner can be used as it is for rust-preventing paints, or can be used with addition of known and commonly used additive components such as pigments, plasticizers, solvents, or colorants. It is also possible to use modified amino resins, en-? This does not in any way preclude the use of a wide range of water-soluble or water-dispersible resins such as acrylic resins.

For example, it can be used as a baking paint in combination with a melamine resin, and especially when a drying oil or its fatty acid is used in the composition of the present invention, it is useful as a paint for drying at room temperature when a metal dryer is added. .

These coating compositions can be applied by dipping, brushing, spraying, rolling, etc., and can be applied to ferrous and non-ferrous metals as well as other surfaces such as wood, paper, plastics or ceramics. It can also be applied to

〔Example〕

Next, the present invention will be explained in more detail with reference to Reference Examples, Examples, and Comparative Examples, where all parts and parts are based on weight unless otherwise specified.

Reference Example 1 [Preparation example of alkyd resin 1 & its derivative (A)] Safflower oil 400II and 4-ntaerythritol 1soII were charged into a reaction vessel equipped with a stirrer, a thermometer and an inert gas introduction tube, and hydroxylated. Add lithium 2
The reaction was carried out by heating at 60° C. for 3 hours.

After confirming the transesterification, the mixture was cooled to 1800°C, and then 31ON of 7-talic anhydride and 110I of p-1·rt-tuterbenzoic acid were added and reacted by heating to 210°C, resulting in an alkyd resin with an acid value of 10 ( A) was obtained. Hereinafter, this will be abbreviated as resin (A-1).

Reference Example 2 (Pl top) Using the same apparatus as Reference Example 1, 350% of linseed oil fatty acid
．． 9 and "4001 of Evicron 4050J, a condensation reaction was carried out until the acid value reached 15, and then 1800
After cooling at t, 100 Ii of phthalic anhydride and 150 I of neointyl glycol were added and reacted at 220° C. for 3 hours to obtain an epoxy ester resin with an acid value of 20. Hereinafter, this will be abbreviated as resin (A-2).

Reference Example 3 (same as above) Using the same apparatus as Reference Example 1, 3 of dehydrated castor oil fatty acid
50Ii and [Epicron 4050JO400J 2
Condensation reaction was carried out at 00°C until the acid value reached 15, then cooled to 180°C, and 100J' of phthalic anhydride and 1501 of neopentyl glycol were added to 220°C.
The reaction was carried out at ℃ for 3 hours to obtain an epoxy ester resin having an acid value of 5. Hereinafter, this will be abbreviated as resin (A-3).

Reference Example 4 (same as above) In a device similar to Reference Example 1, 450Ii of tall oil fatty acid was added.
, 193.9 of glycerin. 3071 of talic anhydride and 50.9 of maleic anhydride were charged and heated to 190° C. to react to obtain an alkyd resin having an acid value of 5.

The resin was then diluted with 519J' of ethyl cellosolve and further diluted with r CAB 551-0. Add 5011 of OIJ (cellulose acetate tottellate manufactured by Eastman Kodak, USA) and heat to 130°C, and add 1001 of styrene and 6 of methyl methacrylate.
6(1' of 0i n-butyl acrylate and 40II of methacrylic acid and 13.9 of tart-butyl perbenzoate were added dropwise over 3 hours to react.)

Four hours after the completion of the dropping, a viscous and transparent vinyl-modified alkyd resin (A) was obtained. Hereinafter, this will be referred to as resin (A-4).
It is abbreviated as

Reference Examples 5 to 10 (same as above) Using the same apparatus as Reference Example 1, the respective alkyd resins and epoxy ester resins obtained in Reference Examples 1 and 3 were acrylic-modified under the conditions shown in Table 1. Various alkyd resin derivatives (A) were prepared using the following methods.In addition, each formulation number in the same table is the number of parts by weight.

Reference Example 11 (same as above) Using the same apparatus as Reference Example 1, 450
193 parts of glycerin, 307 parts of phthalic anhydride, and 50 parts of maleic anhydride were charged and reacted by heating at 190°C to obtain an alkyd resin having an acid value of 5.

The resin was then diluted with 519 parts of ethyl cellosol and then 50 parts of r CAB 551-0.01 J
(Cellosolve acetate butyrate manufactured by Eastman Kodak, USA) was added and heated to 130°C.

Thereafter, 100 parts of styrene, 60 parts of methyl methacrylate, 60 parts of n-butyl acrylate,
A mixture of 40 parts of methacrylic acid and 13 parts of t@rt-butyl perbenzoate was added dropwise over 3 hours to react.

Four hours after the completion of the dropping, a viscous and transparent alkyd resin derivative (4) was obtained. Hereinafter, this will be abbreviated as resin (A-11).

Examples 1 to 11 and Comparative Examples 1 to 7 Antirust pigments and the like were added to 100 parts of the alkyd resin and its derivative obtained in Reference Example 1-11 at the composition ratios shown in Tables 2 and 3. A water-dispersible resin composition for coating was prepared.

At this time, there are two methods: first adding a rust preventive pigment to the alkyd resin or its derivative, mixing it thoroughly, and then dispersing it in water (dispersion method I); A two-pronged method was used, including the method of adding a rust preventive pigment (dispersion method II).

The dispersibility and stability of each of the water-dispersible resin compositions for coating were evaluated, and the results are summarized in Table 2.

Test Examples 1 to 15 For reference, 100 parts of each of the dispersions A1 to 18 shown in Tables 2 and 3 were added with [100 KD J
50 copies of (bengara manufactured by Toda Kogyo ■) and -NS-20
10 parts of calcium carbonate (manufactured by Nitto Funka Co., Ltd.) were separately blended to disperse crosstalk, and then 1 part of 5% cobalt heptathenate was added to each separately to prepare an air-drying red rust paint. (Sample stores 1-13 and 15).

Separately, for the dispersion AlO shown in Table 2, the paint formulation was carried out as in Samples 1-13 and 15, with the addition of a portion of barium metaborate. A red rust paint was prepared (Sample 14).

Various paints were applied to an untreated steel plate that had been degreased with toluene to a dry film thickness of 15 to 20 μm, and then heated at 25°C for 50 minutes.
A cured coating film was obtained by drying for several days.

The paint stability and film performance of each paint and film were evaluated. The results are shown in Table 4 K. [Effects of the Invention] As is clear from the above results, the aqueous dispersion of the resin composition of the present invention is stable, whereas the aqueous dispersion of the resin composition of the present invention is stable. What is obtained is less stable.

Furthermore, while the paint obtained using the resin composition of the present invention has excellent anti-corrosion ability and stability, the paint obtained by adding a rust-preventive pigment after dispersion in water, or when blending the paint, Paints obtained by adding anti-rust pigments are less stable.

The water-dispersible resin composition for coating of the present invention is extremely useful.

Claims (1)

[Claims] 1. Add 0.05 to 20 parts by weight of the anti-rust pigment (B) to 100 parts by weight of the alkyd resin or its derivative (A) and mix thoroughly, and then add the above-mentioned alkyd resin A water-dispersible resin composition for coating with excellent anticorrosion properties, which is dispersed in water by utilizing the hydrophilic groups present in or a derivative thereof (A) and/or by adding an emulsifier (C). 2. The alkyd resin (A) described above may contain oil or fatty acid (
0 to 60 parts by weight of a-1), 5 parts by weight of polyol (a-2)
~40 parts by weight, 10 to 50 parts by weight of polybasic acid (a-3), 0 to 1 of monobasic acid (a-4) of C_6 to C_1_8
5 parts by weight, and 0 to 50 parts by weight of epoxy resin (a-5) based on 100 parts by weight of the total amount of each of the raw materials (a-1) to (a-4) described above, and (
A patent claim characterized in that it is obtained by reacting each of the raw materials a-1) to (a-4) so that the ratio of the number of hydroxyl groups to the number of carboxyl groups becomes 1.0 to 2.0. The composition according to item 1. 3. The alkyd resin derivative (A) described above contains 0 to 60 parts by weight of oil or fatty acid (a-1), polyol (a-
5 to 40 parts by weight of 2), 10 to 5 parts by weight of polybasic acid (a-3)
0 parts by weight, monobasic acid C_6 to C_1_8 (a-4)
0 to 15 parts by weight, and (a-1) to (a-
4) 0 per 100 parts by weight of the total amount of each raw material.
~15 parts by weight of epoxy resin (a-5) is used, and the ratio of hydroxyl group/carboxyl group number in each of the above-mentioned raw materials (a-1) to (a-4) is 1.0 to 2.0. 10 to 9 of the alkyd resin obtained by reacting as follows.
70 to 9.5 parts by weight of α,β-ethylenically unsaturated monomer (a-6) and 20 to 0.5 parts by weight of polyalkylene glycol (meth)acrylate (a
The composition according to claim 1, which is a vinyl-modified alkyd resin obtained by copolymerizing with -7).