JP2513161B2 - Resin composition for low temperature dry paint - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a water-dispersible or water-soluble coating resin composition which gives a coating film excellent in low-temperature curability and corrosion resistance. More specifically, the present invention relates to an epoxy resin,
The present invention relates to a coating resin composition particularly suitable for electrodeposition, which contains an anionic or cationic resin prepared from an unsaturated fatty acid and an ethylenically unsaturated monomer.

Conventionally, electrodeposition paints have been used for various purposes as primers. However, such a coating requires a high temperature of 160 to 180 ° C. to be sufficiently cured, which is not preferable from the viewpoint of energy saving. Low-temperature curing type electrodeposition coatings have been developed in order to improve such defects, but the present situation is that no useful ones have been found yet.

The inventors of the present invention have conducted extensive studies to develop a resin for low temperature curing type paints, and as a result, obtained from a graft polymer containing epoxy resin, unsaturated fatty acid and ethylenically unsaturated monomer as essential components. The resin is excellent in low temperature effect,
The present invention has been completed by providing a coating film having good corrosion resistance and finding that it is suitable as an electrodeposition coating material.

The present invention uses an epoxy resin of 30 to 60% by weight.
And 30 to 60% by weight of unsaturated fatty acid, and if necessary, a monovalent to trivalent organic acid and a monovalent to tetravalent alcohol are added within a total amount of 70% by weight or less. Number average molecular weight obtained by condensation is 500 to 5000
In addition, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, 40 to 80% by weight of the epoxy resin ester intermediate having a weight average molecular weight of 1,000 to 20,000, an acid value of 0 to 20, and a hydroxyl value of 0 to 100. The number average molecular weight obtained by graft-polymerizing 60 to 20% by weight of an ethylenically unsaturated monomer containing at least 5% by weight of at least one selected from the group consisting of diethylaminoethyl acrylate and diethylaminoethyl methacrylate is 1000 to 6000. , A weight average molecular weight of 5,000 to 200,000, and an amine value of 3
There is provided a resin composition for low temperature dry coating, which comprises neutralizing a product of 0 to 100 with an acid and dispersing or dissolving it in water.

Regarding conventional resin compositions for electrodeposition,
Numerous patents have been published in some reviews, such as "Oil and Petroleum.
Chemistry "18 (3), 101-105 (1974)
"Paint technology"1973 (1), 155-164 etc.
It is However, all of these have various drawbacks.
Have, for example, the composition of Japanese Patent Publication No. 51-32655
In some cases, it takes 30 minutes to dry the coating film at 170 ° C.
There is a drawback. Also, J. Oil Col. Chem. Assoc.,5
3, 353-362 (1970), "Room Tempera.
Room temperature for ture Curing Electrodeposited Coatings
An electrodeposition paint that cures at is shown, but this is a two-part system.
Yes, one electrodeposition paint cannot be used for a long time
Yes. On the other hand, the electrodeposition coating composition according to the present invention is
It is a liquid type, stable for a long time, and 80 to 100 ° C.
Sufficient hardness at low temperature drying, corrosion resistance and other general coating performance
Is different from conventional electrodeposition coating compositions in that
There is. The epoxy resin used in the present invention includes bis
Diglycidyl ether type epoxy resin of phenol A
Is suitable, and a molecular weight of 500 or more is required. Fifty
At 0 or less, sufficient quick-drying property and hardness cannot be obtained. Other
The epoxy resin of bisphenol F, phenol
Polyglycidides such as Lunovolatsk and Cresol Novoratsk
Any ether having a melting point of 40 ° C or higher can be used.
The resin composition comprises at least one of the above epoxy resins.
The above must be contained in the intermediate raw material in an amount of 30 to 60% by weight.
Yes.

As the fatty acid used in the present invention, a fatty acid of a drying oil having an iodine value of 130 or more is suitable. Such dry fatty acids include linseed oil fatty acid, eno oil fatty acid,
Examples include cinnamon oil fatty acid and soybean oil. In addition to dry oil fatty acid, semi-dry oil with iodine value of 100 to 130, such as cottonseed oil, rapeseed oil, rice bran oil, etc., or iodine value of 10
A non-drying oil of 0 or less, for example, a fatty acid such as palm oil or coconut oil may be used. Only one of these fatty acids may be used,
You may use 2 or more types. However, in order to obtain sufficient room temperature dryness, the resin composition of the present invention must contain 30 to 60% by weight of a fatty acid having at least one unsaturated carbon-carbon bond in the epoxy resin ester intermediate raw material. .

In the epoxy resin ester intermediate used in the present invention, in addition to the epoxy resin and the unsaturated fatty acid, a 1 to 3 functional acid and a 1 to 4 functional alcohol which are used as a raw material of a usual alkyd are used as raw materials. May be included. Finally, the epoxy resin ester intermediate has a number average molecular weight of 500 to 5,000 and a weight average molecular weight of 1,000 to 2,000.
0, acid value 0 to 50, OH value 0 to 100,
The epoxy resin ester intermediate resin can be synthesized by using one or more kinds of necessary amounts of 1 to 3 functional acid and 1 to 4 functional alcohol, respectively. Examples of the above 1-3 functional acids include various aliphatic carboxylic acids such as acetic acid, butyric acid, oleic acid, various aromatic carboxylic acids such as benzoic acid, tert-butylbenzoic acid, phthalic acid, isophthalic acid, Other examples include various dimer acids, addition products of various fatty acids and maleic acid, trimellitic acid, and the like. Examples of the above-mentioned 1 to 4 functional alcohols include various aliphatic alcohols such as tert-butyl alcohol, amyl alcohol, 2-ethylhexyl alcohol, various aromatic alcohols such as benzyl alcohol, other ethylene glycol and propylene glycol. , Neopentyl glycol, glycerol, trimethylolethane, pentaerythritol and the like.

Since the ring-opening reaction between the epoxy resin and the carboxylic acid is promoted by an amine-based catalyst, a high-boiling amine such as dimethylbenzylamine is added to 1/1 of the epoxy weight.
It is effective to add 00 to 1/1000. The esterification reaction of the hydroxyl group and the carboxyl group is suitably carried out at 150 to 250 ° C.

Since oxygen in the reaction system reacts with the carbon-carbon double bond, it is necessary to proceed the reaction under an atmosphere of an inert gas (nitrogen-carbon dioxide, etc.).

The reaction has a predetermined molecular weight (number average 500 to 5).
000) or a viscosity corresponding thereto and an acid value of 0 to 20 are reached, the reaction is stopped by lowering the temperature or mixing with a water-soluble organic solvent. As the water-soluble organic solvent used, alkanol, for example, methanol, ethanol, propyl alcohol and the like, alcohols such as monoalkylethylene glycol, monoalkyldiethylene glycol and the like are preferred, but other water-soluble solvents, such as acetone, THF, Dioxane etc. can also be used.

The aqueous solvent solution of the epoxy resin ester intermediate is then used in the reaction for graft polymerization with an ethylenically unsaturated monomer. In the graft polymerization reaction, 60 to 20% by weight of the ethylenically unsaturated monomer is added to 40 to 80% by weight of the solid portion of the epoxy resin ester intermediate.
Graft-polymerized to have a number average molecular weight of 1,000 to 6,000,
Weight average molecular weight 5,000 to 200,000, amine value 30
~ 100 graft polymerized resins are synthesized. The ethylenically unsaturated monomer used for this graft polymerization must contain at least 5% by weight of at least one of dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate. Further, other monomers include styrene, acrylic acid esters, methacrylic acid esters, itaconic acid esters, fumaric acid esters, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl lactam, vinyl chloride and the like.

The resulting graft-polymerized resin aqueous solvent solution is neutralized with a neutralizing agent, for example, organic acids such as formic acid, acetic acid and lactic acid or inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and further deionized water is added. This makes it possible to obtain the same stable aqueous solution or dispersion as in the case of the first embodiment.

When electrodeposition coating is carried out using the above aqueous solutions or dispersions, this is first filled in a container so that the electrically conductive anode and the electrically conductive cathode to be coated are dipped, and then both A voltage is applied between the electrodes to electrodeposit an adhesive coating of the coating composition on the cathode. The voltage condition is 1 to 1000V, typically 50 to 300V. The current density usually decreases from a maximum of 0.1 A / cm ² to zero A / cm ² during the electrodeposition process. The pH is usually set to 5-9.

Electrodeposition coating with the composition of the present invention is suitable for conductive substrates such as iron, aluminum, copper and the like. The adhesive coating is usually cured and dried at 120 to 200 ° C, but when the composition of the present invention is used, it is 60 to 120 ° C.
However, it is possible to obtain sufficient hardness, corrosion resistance and other physical properties.

The paint according to the present invention can be applied to various objects to be coated other than metal by using any coating method such as brush coating, spray coating, roller coating and dip coating. It is most suitable for electrodeposition coating on such conductive metal products.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples. Percentages and parts are by weight.

[0017]

EXAMPLE 1 422 parts of linseed oil fatty acid and 43 parts of dehydrated castor oil fatty acid are heated to 140 ° C. in an N ₂ -substituted reaction vessel. After adding 513 parts of epoxy resin (Dainippon Ink KK, Epiclon 1050), heating was further carried out, and when the system became uniform and transparent, 0.5 part of dimethylbenzylamine was added, and further heated to 180 ° C. The temperature is raised and 18 hours
Keep at 0 ° C. After cooling to 120 ° C., 5 parts of maleic anhydride is added and gradually heated, and the temperature is raised to 230 ° C. over 3 hours. The condensation reaction proceeds while maintaining the temperature at 230 ° C, and the acid value becomes 6,
When the Gardner viscosity of a 60% butyl cellosolve solution of the resin reaches V, the temperature is rapidly lowered to 80 ° C., and about 500 parts of butyl cellosolve and about 500 parts of ethyl cellosolve are added.
Parts are added to prepare an epoxy ester intermediate resin solution having a resin non-volatile portion of 50%.

This epoxy ester intermediate resin solution 12
00 parts are heated to 80 ° C. in a reaction vessel with N ₂ substitution. Into this resin container, 160 parts of styrene, 40 parts of lauryl methacrylate, 24 parts of methyl methacrylate, 8 parts of butyl acrylate, 168 parts of dimethylaminoethyl methacrylate and a peroxide polymerization initiator (NOF K.K.
K., perbutyl O) 40 parts of the mixture is added dropwise over 3 hours. Further, the temperature is kept at 80 ° C. for 6 hours to complete the graft polymerization. This graft-polymerized resin solution has a resin non-volatile portion of 62.5%, a Gardner viscosity of X, and a resin non-volatile portion amine value of 60.

160 parts of this graft-polymerized resin solution, 100 parts of diacid titanium (Teikoku Chemical KK, JR600E),
20 parts of butyl cellosolve and 20 parts of ethyl cellosolve are kneaded in a sand mill to prepare a mill base of NV 67% and PWC 50%.

While stirring a mixture of 120 parts of the above graft-polymerized resin solution, 75 parts of this mill base, and 4 parts of acetic acid, 801 parts of ion-exchanged water was gradually added to prepare 1000 parts of an aqueous dispersion for paint for electrodeposition.

The breakdown voltage of the aqueous dispersion is 300V, the pH is 6.0, and 200V on the iron phosphate treated mild steel sheet cathode.
By electrodeposition for 2 minutes and drying at 80 ° C. for 15 minutes, a smooth, hard and flexible coating film having a film thickness of 20 μm was obtained.
This coating film had a pencil hardness H and had a cellophane tape peeling width of 3 mm or less on one side after 200 hours of salt spray test.

Example 2 470 parts of linseed oil fatty acid and 50 parts of dehydrated castor oil fatty acid are heated to 140 ° C. in an N ₂ -substituted reaction vessel. After adding 450 parts of an epoxy resin (Dainippon Ink KK, Epiclon 1050), it is further heated, and when the system becomes uniform and transparent, 0.5 part of dimethylbenzylamine is added and the temperature is further raised to 180 ° C. The temperature is raised and 18 hours
Keep at 0 ° C. After cooling to 120 ° C., 10 parts of maleic anhydride and 20 parts of phthalic anhydride are added and gradually heated, and the temperature is raised to 230 ° C. over 3 hours. When the condensation reaction proceeds while maintaining the temperature at 230 ° C and the acid value is 15 and the Gardner viscosity of the 60% butylcellosolve solution of the resin reaches N, the temperature is rapidly lowered to 80 ° C, and about 500 parts of butylcellosolve and about 500 parts of ethylcellosolve are used. Part is added to the resin non-volatile part 5
Prepare a 0% epoxy ester intermediate resin solution.

This epoxy ester intermediate resin solution 12
00 parts are heated to 80 ° C. in a reaction vessel with N ₂ displacement. To this resin solution, 136 parts of styrene, 46 parts of methyl methacrylate, 168 parts of dimethylaminoethyl methacrylate and a peroxide polymerization initiator (NOF K.K.
K. , Tert-butyl O) (25 parts) is added dropwise over 3 hours. Further, the temperature is kept at 80 ° C. for 6 hours to complete the graft polymerization. This graft-polymerized resin solution has a resin non-volatile portion of 62.5%, a Gardner viscosity of X, and a resin non-volatile portion amine value of 60.

160 parts of this graft-polymerized resin solution, 100 parts of diacid titanium (Teikoku K.K., JR600E)
Part, butyl cellosolve 20 parts and ethyl cellosolve 2
Kneading 0 parts with a sand mill, NV 67%, PWC 50%
Prepare a mill base of.

While stirring a mixture of 120 parts of the above graft-polymerized resin solution, 75 parts of this mill base and 4 parts of acetic acid, 801 parts of ion-exchanged water was gradually added to prepare 1000 parts of an aqueous dispersion for paint for electrodeposition.

The breakdown voltage of the aqueous dispersion was 300 V, the pH was 6.0, and the film thickness was obtained by electrodeposition on the iron phosphate-treated mild steel plate cathode at 200 V for 2 minutes and drying at 80 ° C. for 15 minutes. A smooth, hard, flexible coating of 20μ was obtained.
This coating film had a pencil hardness of H and had a cellophape peeling width of 3 mm or less on one side after 150 hours of a salt water spray test.

Comparative Example 1 Linseed oil fatty acid 363 was placed in a N ₂ -substituted reaction vessel.
Parts, 371 parts phthalic anhydride, trimethylolpropane 8
Charged 0 parts and 186 parts of pentaerythritol, and 3
Heat gradually to 190 ° C. over time. When the condensation reaction proceeds while maintaining the temperature at 190 ° C and the Gardner viscosity of the 60% butyl cellosolve solution of the resin is 55 and the resin reaches R, the temperature is rapidly lowered to 80 ° C, and about 400 parts of isopropyl alcohol is added to the resin. A resin solution having a solid content of 70% is prepared.

143 parts of the resin solution, 100 parts of titanium dioxide (TEKKO K.K., JR600E) and 57 parts of isopropyl alcohol were kneaded in a sand mill to obtain NV67.
%, PWC 50% millbase.

While stirring a mixture of 107 parts of the resin solution, 75 parts of the mill base and 6.5 parts of triethylamine, 811.5 parts of ion-exchanged water was gradually added to prepare 1000 parts of an aqueous dispersion for paint for electrodeposition.

The coating film obtained in the same manner as in Example 1 had a blur pencil hardness of 4B or less and a cellophape peeling width of 8 mm or more on one side after 100 hours of the salt water spray resistance test.

Comparative Example 2 366 parts of linseed oil fatty acid are heated to 180 ° C. in a reaction vessel substituted with N ₂ . Epoxy resin (Epiclon 40
50) 95 parts and 0.1 part of catalyst dimethylbenzylamine are added, the temperature is raised again to 180 ° C., and the temperature is kept at 180 ° C. for 1 hour.
After cooling to 150 ° C., 321 parts of phthalic anhydride and 218 parts of pentaerythritol are added and gradually heated, and the temperature is raised to 190 ° C. over 3 hours. When the condensation reaction proceeds while keeping the temperature at 190 ° C and the Cardner viscosity of the acid value of 70 and the resin 60% butyl cellosolve reaches W, the temperature is rapidly lowered to 80 ° C, and isopropyl alcohol of about 400 is added.
Parts are added to prepare a resin solution having a resin solid part of 70%.

An aqueous dispersion of a coating material for electrodeposition was prepared in the same manner as in Comparative Example 1, and electrodeposition coating was further performed. The resulting coating film had a pencil hardness of F-H and a cellotape peeling width after salt water spray test 100 of about 5 mm on one side.

Claims (1)

(57) [Claims] 1. An epoxy resin of 30 to 60% by weight and an unsaturated fatty acid of 30 to 60% by weight are further added, if necessary.
The number average molecular weight obtained by addition or condensation of a monovalent to trivalent organic acid and a monovalent to tetravalent alcohol within a range of 70% by weight or less is 500 to 5000, and the weight average molecular weight is 1000. ~ 20,000, acid value 0-20
And 40-80% by weight of the epoxy resin ester intermediate having a hydroxyl value of 0-100, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate,
The number average molecular weight obtained by graft-polymerizing 60 to 20% by weight of an ethylenically unsaturated monomer containing at least 5% by weight of at least one selected from the group consisting of diethylaminoethyl acrylate and diethylaminoethyl methacrylate is 1000 to 6000. Having a weight average molecular weight of 5,000 to 200,000 and an amine value of 30 to 10
A resin composition for a low-temperature coating composition, which is obtained by neutralizing a product of 0 with an acid and dispersing or dissolving it in water.