JP5426436B2 - Modified phenolic resin and aqueous coating composition containing the same - Google Patents

Description

  The present invention relates to a phenol resin modified with a maleated unsaturated fatty acid and an aqueous coating composition containing the same.

  An anticorrosion paint is used to suppress rusting and prevent corrosion by applying to a metal material. Conventionally, epoxy resins and phenol resins having high material adhesion and low permeability of water or oxygen, which are corrosion factors, have been frequently used as binders for anticorrosion paints. Such anticorrosion paints are generally used as solvent-type paints diluted with organic solvents. In particular, phenolic resins have been frequently used because of their excellent anticorrosion performance.

  In general, it is desirable to use a cured coating film in order to obtain an anticorrosion coating film excellent in solvent resistance and durability. However, unmodified phenolic resin itself has poor curability, so that it has long been used together with a curing agent or modified with drying oil. For example, Patent Document 1 discloses a method for producing a dry oil-modified phenol resin.

  In recent years, the transition from solvent-based paints to water-based paints has been promoted in order to protect the environment and reduce VOCs. However, since the drying oil-modified phenolic resin, which is originally a hydrophobic substance, does not dissolve or disperse in water as it is, an anticorrosion coating using a phenolic resin as a binder has not been made into an aqueous coating. Patent Document 2 discloses a method for producing an oil-modified phenol resin emulsion using a water-soluble polymer as a protective colloid. However, the water-based paint using this phenolic resin contains a large amount of water-soluble polymer which is a water-eluting component, so that the water resistance of the coating film is inferior and sufficient anticorrosion performance cannot be exhibited.

JP-A-55-73721 JP 2009-67921 A

  An object of the present invention is to produce a phenol resin having water dispersibility and to obtain an aqueous coating composition excellent in coating film performance using it as a binder.

  As a result of intensive studies to solve the above problems, the present inventors have determined that phenolic resins modified with unsaturated fatty acids maleated with maleic anhydride have their acid anhydride groups water, alcohol, amine, etc. It was found that the aqueous coating material using the aqueous dispersion showed excellent coating film performance and completed the present invention.

Thus, the present invention comprises the following items.
1. An aqueous dispersion of an unsaturated fatty acid-modified phenol resin in which the unsaturated fatty acid is maleated with maleic anhydride, and the unsaturated fatty acid-modified phenol resin is a carboxyl obtained by ring opening of an anhydride group derived from maleic anhydride An aqueous dispersion of an unsaturated fatty acid-modified phenolic resin having a group .
2. Item 2. The unsaturated fatty acid-modified phenolic resin aqueous dispersion according to Item 1, wherein the unsaturated fatty acid raw material is at least one selected from cashew oil, tall oil and linseed oil.
3 . Item 3. The aqueous dispersion of unsaturated fatty acid-modified phenolic resin according to Item 1 or 2 , wherein a resin acid value derived from a carboxyl group generated by ring opening of an anhydrous group is 40 to 100.
4 . Item 4. The unsaturated group according to any one of items 1 to 3, wherein the carboxyl group in the unsaturated fatty acid-modified phenol resin is amine-neutralized and the amine neutralization degree is 0.60 to 1.00. An aqueous dispersion of a fatty acid-modified phenolic resin.
5 . Item 5. An aqueous coating composition comprising an aqueous dispersion of an unsaturated fatty acid-modified phenolic resin according to any one of Items 1 to 4 and a pigment.

  According to the present invention, it is possible to obtain a modified phenolic resin that can be made into a stable aqueous dispersion using a natural product-derived raw material. The aqueous coating composition containing the aqueous dispersion has a low VOC discharge amount and can be dried at room temperature, and the cured coating film exhibits excellent coating performance and can be suitably used particularly as an anticorrosion coating.

  The present invention will be described in more detail below.

Phenolic resin
As the phenol resin used in the present invention, a novolac type phenol resin or a resol type phenol resin is used. A phenol resin is obtained by reaction of phenols with carbonyl compounds such as aldehydes and ketones. Examples of phenols include phenol, bisphenol A, bisphenol F, cresol, xylenol, and nonylphenol. Examples of aldehydes include formaldehyde. As formaldehydes, for example, formalin, paraformaldehyde and the like are common.

  As for the molecular weight of the phenol resin, the number average molecular weight is preferably 300 to 4000 in the novolak type phenol resin, and the number average molecular weight is preferably 200 to 2000 in the resol type phenol resin. It is preferable that the number average molecular weight is in the above-mentioned range since a balance between corrosion resistance and smoothness can be obtained.

  In this specification, the number average molecular weight and the weight average molecular weight are the retention time (retention capacity) measured using a gel permeation chromatograph (GPC), the retention time of standard polystyrene with a known molecular weight measured under the same conditions ( It is a value obtained by converting to the molecular weight of polystyrene by (retention capacity). Specifically, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” are used as columns. ”And“ TSKgel G-2000HXL ”(trade names, all manufactured by Tosoh Corporation), a differential refractometer is used as a detector, mobile phase: dimethyl sulfoxide tetrahydrofuran measurement temperature: 40 ° C., flow rate It can be measured under the condition of 1 mL / min.

Unsaturated fatty acids used for modification
Examples of the unsaturated fatty acid used for the modification of the phenol resin in the present invention include, for example, cashew oil, linseed oil, tall oil, eno oil, tung oil, sesame oil, rapeseed oil, cottonseed oil, soybean oil, camellia oil, olive oil, castor oil And various terpenes including tall oil vegetable oil and rosin (eg, abietic acid, pimaric acid). These are raw materials derived from natural products, and can be used alone or in admixture of two or more. Cashew oil is also a natural phenolic substance.

  Among these raw materials, those selected from cashew oil, tall oil, and linseed oil are preferable from the viewpoints of quality stability, ease of handling, and physical properties of the coating film, and cashew oil is particularly preferable.

  These raw materials may be used for the modification reaction as they are (for example, in the case of many vegetable oils, they are fatty acid triglycerides), or fatty acids isolated by decomposition and purification may be used. Examples of such fatty acids include linoleic acid, linolenic acid, eleostearic acid, stearidonic acid, and the like.

  As a method for synthesizing the modified phenolic resin used in the present invention, for example, the above-mentioned raw materials containing phenols, aldehydes, and unsaturated fatty acids are reacted (modified) in the presence of an acidic catalyst to produce a novolak-type modified phenol. Resole-modified phenolic resin obtained by reacting (modifying) a raw material containing the above-described phenols and unsaturated fatty acid in the presence of an acidic catalyst, and then reacting the aldehyde in the presence of an alkaline catalyst. And a method of reacting (modifying) the above-described phenols and oil in the presence of an acidic catalyst and then reacting with an aldehyde to obtain a novolac-type modified phenol resin.

  Further, after resol type or novolac type phenol resin is synthesized, modification with a raw material containing unsaturated fatty acid may be performed.

  Examples of acidic catalysts that can be used in the synthesis reaction include oxalic acid, hydrochloric acid, sulfuric acid, diethyl sulfuric acid, phosphoric acids, phenolsulfonic acid, and the like, divalent metal (Ca, Mg, Zn, etc.) acetates, boric acid, and divalent metals. (Ca, Mg, Zn, etc.) borate, paratoluenesulfonic acid, methanesulfonic acid, boron trifluoride, stannic chloride, ferric chloride, perfluoromethanesulfonic acid, etc. alone or in combination Can be used.

  As the usage-amount of the said acidic catalyst, it can be 0.001-0.05 mol normally with respect to 1 mol of phenols.

  Examples of the alkaline catalyst that can be used include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide, tertiary amines such as ammonia water and triethylamine, and alkaline earth metals such as calcium, magnesium and barium. These oxides and hydroxides, alkaline substances such as sodium carbonate and hexamethylenetetramine can be used alone or in combination of two or more.

  Although the usage-amount of the said alkaline catalyst is not specifically limited, It can be 0.01-0.1 mol normally with respect to 1 mol of phenols.

  In the synthesis of a phenol resin modified with a maleated unsaturated fatty acid used in the present invention, the ratio of the modified component to the phenol resin is 40 to 98% by weight of the modified component based on the total solid content of the modified phenol resin. It is preferable that More preferably, it is 50 to 95% by weight. If the amount of the modifying component is less than this range, there may be a case where sufficient water dispersibility may not be obtained when the water-dispersed ring is opened after neutralization and neutralization after maleation. When used as a paint, sufficient physical properties of the coating film may not be obtained. Here, the denatured component refers to a maleated fatty acid component.

Maleinization
In the present invention, the unsaturated fatty acid is maleated. The maleation of the unsaturated fatty acid may be performed before or after the modification of the phenol resin, but is modified with the unsaturated fatty acid in order to avoid unnecessary ring-opening reaction of the anhydrous group by the alkaline catalyst. It is preferable to maleate the phenol resin.

  The maleation reaction can be performed by a known method. For example, the unsaturated fatty acid-modified phenol resin and maleic anhydride are mixed, and the maleation of the unsaturated group can be promoted by mixing and stirring at a temperature of 160 ° C. or higher, preferably 160 ° C. to 220 ° C. At this time, if the reaction is carried out at a high temperature exceeding 220 ° C., undesirable side reactions such as thermal degradation of the resin, oxidation of unsaturated groups, and polymerization may occur.

  The amount of maleic anhydride when maleating is preferably 40 to 100 equivalent, more preferably 50 to 80 equivalent in terms of resin acid value after maleation (unit: mgKOH / g). . If the acid value derived from maleic anhydride is less than 40, water dispersibility may be insufficient. If the acid value derived from maleic anhydride exceeds 100, the anticorrosion performance may be insufficient when used as a coating component.

  Here, the resin acid value can be determined by titrating with potassium hydroxide in which the resin is dissolved in a mixed solvent containing alcohol and dissolved in ethanol. At this time, in addition to the original protonic acid, the acid anhydride introduced by maleation is subjected to ring-opening addition with an alcohol such as ethanol to form an ester bond and one protonic acid, and then contained in 1 g of organic solid content in the system This is a value obtained as a numerical value when the mass of potassium hydroxide required to neutralize all the protonic acids expressed in mg, and can be measured based on JIS K-6901-2008.

Water dispersion
In the present invention, the maleated unsaturated fatty acid-modified phenol resin opens a maleic anhydride group to a carboxyl group. At this time, when hydrolyzing with water as a ring-opening agent, the anhydrous group becomes two carboxyl groups. Alcohol decomposition (half-esterification) using alcohol as a ring-opening agent results in a carboxyl group and an alkyl ester. In any case, the ring-opening reaction proceeds by adding excess water or alcohol equivalent to or more than the anhydrous group and heating, but at this time, a small amount of catalyst may be used. A known catalyst can be used without any problem.

  Carboxyl groups and amides can also be formed by adding a primary or secondary amine as a ring-opening agent to an anhydrous group and subjecting it to amine decomposition (half amidation).

  In the half esterification and half amidation described above, alcohol or amine is reacted directly with an anhydrous group, but after ring opening with water, it is less than half of the total amount of carboxyl groups, ie 0.5 equivalent or less. These alcohols or amines can also be condensed into esters or amides.

  When alcohol or amine is used as a ring-opening agent or a condensing agent, the alcohol or amine is preferably a compound having a nonionic hydrophilic group in the molecule from the viewpoint of water dispersibility. Examples of such a compound include polyalkylene glycol, polyalkylene glycol monoalkyl ether, polyalkylene glycol-modified amine and the like.

  The maleated unsaturated oil-modified phenol resin of the present invention can be dispersed in water by neutralizing the carboxyl group generated by ring opening of the anhydrous group. As the neutralizing agent, any basic substance can be used without any problem, but an amine is preferably used from the viewpoint of anticorrosion.

  Examples of such amines include tertiary amines such as triethylamine, tributylamine, dimethylethanolamine and triethanolamine; secondary amines such as diethylamine, dibutylamine, diethanolamine and morpholine; primary amines such as propylamine and ethanolamine; ammonia and the like Is mentioned. The amount of the basic substance used is preferably in the range of 0.6 to 1.0 molar equivalent with respect to the carboxyl group in the maleated unsaturated oil-modified phenol resin. If the amount of the basic substance is less than 0.6 molar equivalent, sufficient water dispersibility may not be obtained. On the other hand, if the amount of the basic substance is more than 1.0 molar equivalent, the corrosion resistance and water resistance may be adversely affected.

Water-based paint composition
If necessary, pigments such as coloring pigments, extender pigments, rust preventive pigments; pigment dispersants, anti-settling agents, thickeners, antifoaming agents, antifreezing agents Conventional additives for paints such as an agent, an antiseptic, an organic solvent, a film-forming aid, and a coating surface modifier, and an aqueous resin other than a modified phenolic resin can be blended.

  When the pigment is blended in the aqueous coating composition containing the aqueous dispersion of the present invention, the maleated unsaturated fatty acid-modified phenolic resin aqueous dispersion obtained in the present invention can be used for the pigment dispersion resin. This is preferable because other additives such as a dispersion stabilizer are unnecessary.

  The aqueous coating composition containing the aqueous dispersion of the present invention can be applied by a conventionally known method such as spray coating, roller coating or brush coating.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, both “parts” and “%” are based on mass.

Example 1
A flask equipped with a heating device, thermometer, condenser, and stirrer was charged with 100 parts of cashew oil (product name CX-1000, manufactured by Cashew Co., Ltd.) and 1.0 part of boric acid. 25 parts of an aqueous formalin solution was added dropwise over 2 hours. In order to remove water generated by condensation of water or formalin as a solvent, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 8.12 parts of maleic anhydride was charged, the temperature was raised to 180 ° C., and the mixture was aged for 2 hours. Subsequently, 5.0 parts of deionized water was added dropwise over 1 hour while cooling. After aging at 120 ° C. for 2 hours, 40 parts of butyl cellosolve was added to obtain a maleated cashew novolak resin having a number average molecular weight of 3000 and an acid value of 80 derived from a carboxyl group. Further, 17 parts of triethylamine equivalent to 1.0 equivalent to the carboxyl group added to the maleated cashew novolak resin was neutralized, and deionized water was gradually added while stirring to obtain a water dispersion. It was. The maleated cashew-modified novolak resin aqueous dispersion 1 had a solid content of 30% and a viscosity of 4000 mPa · s.

Example 2
A flask equipped with a heating device, a thermometer, a condenser, and a stirrer was charged with 100 parts of cashew oil and 1.0 part of boric acid. After raising the temperature to 130 ° C., 25 parts of 37% formalin solution was added dropwise over 2 hours. . In order to remove water which is a solvent or water generated by condensation, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 8.12 parts of maleic anhydride was charged, the temperature was raised to 180 ° C., and aging was performed for 2 hours. Next, the mixture was cooled to 120 ° C., charged with 10 parts of Jeffamine M-1000 (manufactured by HUNTSMAN, a polyether compound having a primary amine group), and aged at the same temperature for 1 hour. Subsequently, 5.0 parts of deionized water was added dropwise over 1 hour. After aging at 120 ° C. for 2 hours, 40 parts of butyl cellosolve was added to obtain a polyether-modified maleated cashew novolac resin having a number average molecular weight of 3100 and an acid value of 65 derived from a carboxyl group. Further, neutralize by adding 10.3 parts of triethylamine equivalent to 1.0 times equivalent to the carboxyl group added to the obtained polyether-modified maleated cashew novolak resin, and gradually add deionized water while stirring. An aqueous dispersion was obtained. The resulting polyether-modified maleated cashew-modified novolak resin aqueous dispersion 2 had a solid content of 30% and a viscosity of 3000 mPa · s.

Example 3
A flask equipped with a heating device, thermometer, condenser, and stirrer was charged with 25 parts of phenol, 75 parts of cashew oil, and 1.0 part of boric acid, heated to 130 ° C., and then 25 parts of 37% formalin solution for 2 hours. It was dripped over. In order to remove water which is a solvent or water generated by condensation, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 8.12 parts of maleic anhydride was charged, the temperature was raised to 180 ° C., and aging was performed for 2 hours. Subsequently, 5.0 parts of deionized water was added dropwise over 1 hour while cooling. After aging at 120 ° C. for 2 hours, 40 parts of butyl cellosolve was added to obtain a maleated cashew novolak resin having a number average molecular weight of 1200 and an acid value of 80 derived from a carboxyl group. Further, 17 parts of triethylamine equivalent to 1.0 equivalent to the carboxyl group added to the maleated cashew novolak resin was neutralized, and deionized water was gradually added while stirring to obtain a water dispersion. It was. The maleated cashew-modified novolak resin aqueous dispersion 3 had a solid content of 30% and a viscosity of 1000 mPa · s.

Example 4
A flask equipped with a heating device, thermometer, condenser, and stirrer was charged with 50 parts of phenol, 50 parts of linseed oil and 1.0 part of boric acid, heated to 130 ° C., and then 20 parts of 37% formalin solution for 2 hours. It was dripped over. In order to remove water which is a solvent or water generated by condensation, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 8.12 parts of maleic anhydride was charged, the temperature was raised to 180 ° C., and aging was performed for 2 hours. Subsequently, 5.0 parts of deionized water was added dropwise over 1 hour while cooling. After aging at 120 ° C. for 2 hours, 40 parts of butyl cellosolve was added to obtain a linseed modified maleated novolak resin having a number average molecular weight of 1000 and an acid value of 80 derived from a carboxyl group. Further, 17 parts of triethylamine equivalent to 1.0 times equivalent to the carboxyl group added to the linseed oil-modified maleated novolak resin was neutralized, and deionized water was gradually added while stirring to disperse the water. Got. The maleated linseed oil-modified novolak resin water dispersion 4 had a solid content of 30% and a viscosity of 800 mPa · s.

Comparative Example 1
A flask equipped with a heating device, a thermometer, a condenser, and a stirrer was charged with 100 parts of cashew oil and 1.0 part of boric acid. After raising the temperature to 130 ° C., 25 parts of 37% formalin solution was added dropwise over 2 hours. . In order to remove water which is a solvent or water generated by condensation, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 100 parts of polyacrylamide (Polystron 117, 15% aqueous solution, manufactured by Arakawa Chemical Industries, Ltd.) was added, and deionized water was gradually added while stirring to obtain a water dispersion. The obtained cashew-modified novolak resin aqueous dispersion 5 had a solid content of 30% and a viscosity of 300 mPa · s.

Comparative Example 2
A flask equipped with a heating device, a thermometer, a condenser, and a stirrer was charged with 100 parts of cashew oil and 1.0 part of boric acid. After raising the temperature to 130 ° C., 25 parts of 37% formalin solution was added dropwise over 2 hours. . In order to remove water which is a solvent or water generated by condensation, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 4.5 parts of maleic anhydride and 0.02 parts of copper naphthenate were added, the temperature was raised to 180 ° C., and the mixture was aged for 2 hours. Subsequently, 5.0 parts of deionized water was added dropwise over 1 hour while cooling. After aging at 120 ° C. for 2 hours, 40 parts of butyl cellosolve was charged to obtain a maleated cashew-modified novolak resin having a number average molecular weight of 2900 and an acid value of 45 derived from a carboxyl group. Further, 9.24 parts of triethylamine equivalent to 1.0 times equivalent to the carboxyl group added to the maleated cashew-modified novolak resin was neutralized, and deionized water was gradually added while stirring to disperse the water. A body was created, but after several hours it was separated into an aqueous layer and an oil layer.

Comparative Example 3
A flask equipped with a heating device, a thermometer, a condenser, and a stirrer was charged with 100 parts of cashew oil and 1.0 part of boric acid. After raising the temperature to 130 ° C., 25 parts of 37% formalin solution was added dropwise over 2 hours. . In order to remove water which is a solvent or water generated by condensation, all substances distilled out were discharged out of the system. After completion of the dropwise addition, the mixture was reacted at the same temperature for 1 hour, then heated to 170 ° C. and the distillate was removed under reduced pressure. Thereafter, 8.12 parts of maleic anhydride and 0.02 part of copper naphthenate were charged, the temperature was raised to 180 ° C., and aging was performed for 2 hours. Subsequently, 5.0 parts of deionized water was added dropwise over 1 hour while cooling. After aging at 120 ° C. for 2 hours, 40 parts of butyl cellosolve was added to obtain a maleated cashew-modified novolak resin having a number average molecular weight of 3000 and an acid value of 80 derived from a carboxyl group. Further, 8.5 parts of triethylamine equivalent to 0.5 times equivalent to the carboxyl group added to the maleated cashew modified novolak resin was neutralized, and deionized water was gradually added while stirring to disperse the water. A body was created, but after several hours it was separated into an aqueous layer and an oil layer.

Examples of water-based paints
Example 5
200 parts of maleated cashew-modified novolak resin aqueous dispersion 1 having a solid content of 30% by mass obtained in Example 1 (solid content 60 parts), 5.0 parts of carbon MA-100 (Note 1), talc MA (Note 2) ) 120 parts, EXPERT NP-1020C (Note 3) 40 parts, deionized water 85 parts were added to a ball mill and stirred for 20 hours to obtain a pigment dispersion paste having a solid content of 50%. The obtained pigment dispersion paste was mixed with 450 parts (solid content 225 parts) and maleated cashew modified novolak resin water dispersion-1 133 parts (solid content 40 parts), and 80 parts of deionized water was gradually added while stirring. In addition, an aqueous paint-1 having a solid content of 40% was obtained.
(Note 1) Carbon black MA-100: Carbon black, trade name, manufactured by Mitsubishi Chemical Corporation
(Note 2) Talc MA: manufactured by Hayashi Kasei Co., Ltd., trade name, talc, average particle size 14 μm, oil absorption 27 ml /
100g
(Note 3) EXPERT NP-1020C: manufactured by Toho Chemical Co., Ltd., trade name, calcium phosphite Examples 6-8
In the same manner as in Example 5, aqueous paints 2 to 4 were obtained with the formulations shown in Table 1.

Comparative Example 4
In the same manner as in Example 1, water-based paint-5 was obtained with the formulation shown in Table 1.

Coating performance evaluation
The degreased 0.8 mm thick untreated cold-rolled steel sheet was spray-coated with the aqueous paints 1 to 5 obtained in Examples 5 to 8 and Comparative Example 4 so that the dry film thickness was 20 ± 2 μm. . The obtained coated plate was forcibly dried at 75 ° C. for 20 minutes using an electric hot air dryer, and then subjected to aging (curing drying) at room temperature (23 ° C.) for 7 days to obtain a test plate.

  Table 2 shows the results of the test plate subjected to the test by the test method described later.

(Note 4) Paint stability: Each aqueous paint was placed in a 250 ml glass container and stored in the dark at 40 ° C. for 30 days to check the condition.
○ indicates neither gelation nor separation of the paint.
Δ indicates at least one of an increase in viscosity that does not lead to gelation of the paint and a mild separation that is uniform when stirred.
X indicates at least one of gelation and irreversible significant separation of the paint.
(Note 5) Finishing property: The appearance of the coated surface of each test plate was visually evaluated.

○ indicates smoothness and no problem.
For Δ, at least one kind of decrease in repellency, dents and cloudiness is slightly observed on the coated surface.
In x, the decrease in at least one of repellency, dents and cloudiness on the coated surface is large.
(Note 6) Pencil hardness: In accordance with JIS K 5600-5-4, apply a pencil lead at an angle of about 45 ° to the test coating plate surface, and push forward against the test coating plate surface to the extent that the core does not break. It moved about 10 mm at a uniform speed. The hardness symbol of the hardest pencil that did not tear the coating film was defined as pencil hardness.
(Note 7) Chemical resistance: The coated surface after each test plate with the substrate exposed surface sealed in a 5% concentration sulfuric acid aqueous solution at 60 ° C. for 3 hours was visually evaluated.
A: There is no abnormality in the coating film.
○ is a level where there is no problem as a product, although slight gloss is recognized in the coating film.
Δ indicates either swelling or cracking in the coating film.

X: A blister or crack is remarkably recognized in the coating film.
(Note 8) Water resistance: Each test plate was immersed in deionized water at 23 ° C. for 72 hours to evaluate the coated surface.
◎ is good and has no problem.
○ is a level where there is no problem as a product although some glossiness is seen.
Δ indicates either blistering or discoloration.
X indicates that either blistering or color fading is large.
(Note 9) Corrosion resistance: A cross-cut flaw was made in the coating film of each test plate with a knife, and this was subjected to a salt water spray test according to JIS Z-2371 for 480 hours. After the test, evaluation was made based on the following criteria based on the rust and blister width from the knife scratch.
◎: The maximum width of rust and blisters is less than 2 mm from the cut part (one side).
○ indicates that the maximum width of rust and blisters is 2 mm or more and less than 3 mm (one side) from the cut part.
Δ indicates that the maximum width of rust and swelling is 3 mm or more and less than 4 mm from the cut part (one side).
X: The maximum width of rust and blisters is 4 mm or more from the cut part (one side).

  The coating films of Examples 5 to 8 are superior to the coating film of Comparative Example 4 in chemical resistance, water resistance, and corrosion resistance.

Claims (5)

An aqueous dispersion of an unsaturated fatty acid-modified phenol resin in which the unsaturated fatty acid is maleated with maleic anhydride, and the unsaturated fatty acid-modified phenol resin is a carboxyl obtained by ring opening of an anhydride group derived from maleic anhydride An aqueous dispersion of an unsaturated fatty acid-modified phenolic resin having a group . The aqueous dispersion of unsaturated fatty acid-modified phenolic resin according to claim 1, wherein the raw material of the unsaturated fatty acid is at least one selected from cashew oil, tall oil and linseed oil. The aqueous dispersion of an unsaturated fatty acid-modified phenol resin according to claim 1 or 2 , wherein a resin acid value derived from a carboxyl group generated by ring opening of an anhydrous group is 40 to 100. Carboxyl groups in the unsaturated fatty acid-modified phenolic resin is amine-neutralized IteKatsu amine neutralization degree according to claim 1, characterized in that a 0.60 to 1.00 An aqueous dispersion of unsaturated fatty acid-modified phenolic resin. An aqueous coating composition comprising an aqueous dispersion of an unsaturated fatty acid-modified phenol resin according to any one of claims 1 to 4 and a pigment.