JPH05156137A - Thermosetting water-dispersible resin composition and coating composition - Google Patents

Abstract

PURPOSE:To provide a thermosetting water-dispersible resin compsn. and a coating compsn. which are excellent in dispersion stability in water and give coating films excellent in physical properties such as hardness, and chemical resistance. CONSTITUTION:A water-sol. solvent, a neutralizing agent, and water are added to an oil-free alkyd resin having an acid value of 10-40, a hydroxyl value of 50-200, and a number-average mol.wt. of 1,000-5,000 and prepd. by reacting a polyhydric alcohol component contg. 2-butyl-2-ethyl-1, 3-propanediol and polyoxyethylene glycol having a mol.wt. of 600-20,000 with a polybasic acid, thus giving the objective thermosetting water-dispersible resin compsn. The compsn. is mixed with an amino resin to give a coating compsn.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermosetting water dispersion which is used for coating steel furniture, automobiles, etc., and has excellent dispersion stability and hardness of the resulting coating film and other physical properties. The present invention relates to a resin composition and a coating composition.

[0002]

2. Description of the Related Art In recent years, water-based paints have attracted attention from the viewpoint of resource saving and environmental protection. In particular, water-dispersed paints generally use less organic solvents and organic amines than water-soluble paints, and are preferable from the viewpoint of resource saving and environmental protection. Further, since the solvent volatilizes quickly and the coating material exhibits a non-Newtonian flow, it has the advantage of being difficult to drip and being excellent in coating workability.

In Japanese Patent Laid-Open No. 54-107932, a water-soluble solvent is added to a polyoxyethylene glycol-modified alkyd resin obtained by mixing specific components, and one of the carboxyl groups in the resin is added. A method for producing a thermosetting water-dispersed resin composition having excellent low-temperature curability, which comprises emulsifying and dispersing the resin in water after neutralizing all or part of the resin, is described.

Further, JP-A-52-82936 discloses a water-dispersible resin obtained by using a polymerizable monomer having a zwitterionic structure and another monomer copolymerizable with the monomer as a polymerization component. And a aminoplast resin, which can provide a coating film having good durability at a relatively low temperature in a short time, are disclosed.

[0005]

Problems to be Solved by the Invention JP-A-54-1079
The water-dispersed resin composition described in JP-A No. 32 is excellent in low-temperature curability, but when it contains an oil component in an amount of 10% by weight or more, hardness when used for automobile intermediate coating, etc. The physical properties (elongation, strength, etc., hereinafter simply referred to as physical properties) of the water-dispersible resin composition are not sufficient, and the composition having an oil component of less than 10% by weight cannot balance hydrophilicity and lipophilicity, and the dispersion stability of the water-dispersed resin composition is Inferior

Further, the thermosetting coating composition disclosed in JP-A-52-82936 is excellent in stability and hardness of the water-dispersed resin composition, but when used for intermediate coating of automobiles, etc. In addition, the physical properties are insufficient.

Therefore, the object of the present invention is to provide a water-dispersible resin composition and a coating composition which produce a coating film which is excellent in water dispersion stability, hardness and other physical properties and chemical resistance. And

[0008]

The present invention focuses on the fact that an oil-free alkyd resin containing no oil component has an excellent balance of hardness and physical properties, and utilizes its characteristics to stabilize the stability of the water-dispersed resin composition. The problem is solved by using 2-butyl-2-ethyl-1,3-propanediol having high lipophilicity in order to improve

That is, the present invention relates to (A) 2-butyl-
2-ethyl-1,3-propanediol and molecular weight 60
Polyhydric alcohol component containing 0 to 20,000 polyoxyethylene glycol and acid value (solid) 10 to 40 and hydroxyl value (solid) 40 obtained by reacting polybasic acid
To 200, a number average molecular weight of 1000 to 5000, and a thermosetting property obtained by adding a water-soluble solvent, a neutralizing agent for neutralizing a part or all of carboxyl groups in the resin, and water to the oil-free alkyd resin. The present invention relates to a water-dispersed resin composition, a coating composition containing the thermosetting water-dispersed resin composition and an amino resin.

The present invention will be described in detail below. The (A) component 2-butyl-2-ethyl-1,3-propanediol used in the present invention is blended in a proportion of 10 to 40% by weight based on the total amount of the polyhydric alcohol component and the polybasic acid. It is preferable that the content is 15 to 30% by weight. If this amount is less than 10% by weight, the lipophilicity and hydrophilicity will not be balanced, and the dispersion stability of the resulting water-dispersed resin composition will tend to be poor. If it exceeds 40% by weight, the resin structure will become linear. The resulting coating film has excellent physical properties, but the hardness tends to decrease.

The thermosetting water-dispersed resin composition of the present invention comprises
As the component (B), one or more polyoxyethylene glycols having a molecular weight of 600 to 20,000 can be used. When the molecular weight is less than 600, the hydrophilicity is large and the water resistance of the resulting coating film is poor, and when it exceeds 20,000, the lipophilicity is large and the dispersion stability of the resulting water-dispersed resin composition is poor. The blending amount of the component (B) is preferably 3 to 25% by weight, and particularly preferably 5 to 20% by weight based on the total amount of the polyhydric alcohol component and the polybasic acid. If this blending amount is less than 3% by weight, the particle size of the resulting water-dispersed resin composition tends to be large and the dispersion stability tends to be poor. On the other hand, if it exceeds 25% by weight, the resulting water-dispersed resin composition has a small particle size and a high viscosity, so that the solid content of the coating composition tends to decrease and the sagging property of the coating film tends to decrease.

In the present invention, in addition to the components (A) and (B), a polyhydric alcohol having 2 to 4 hydroxyl groups in one molecule (provided that the components (A) and (B) are excluded) is used. be able to. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethylol, methylpentanediol. , Glycerin, trimethylolethane, trimethylolpropane, tris (2-hydroxyethyl) isocyanurate, pentaerythritol, monoglycidyl ester of versatic acid, monoglycidyl ester of p-t-butylbenzoic acid, ε-caprolactam and the like. These polyhydric alcohols can be appropriately selected and used from the viewpoint of coating film performance.

The content of the polyhydric alcohol is preferably 10 to 45% by weight, more preferably 20 to 40% by weight based on the total amount of the polyhydric alcohol component and the polybasic acid. If the blending amount is less than 10% by weight, the resin structure becomes linear and the resulting coating film has excellent physical properties, but the hardness tends to decrease. On the other hand, if it exceeds 45% by weight, the resin structure has a small molecular weight and a high hydroxyl value, and the resulting coating film has excellent hardness, but the physical properties tend to deteriorate.

The polybasic acid used in the present invention is preferably a polybasic acid having 2 to 3 carboxyl groups in one molecule, such as phthalic acid, isophthalic acid, terephthalic acid, dimethyl terephthalate, tetrahydrophthalic acid and hexa. Hydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, hymic acid, sebacic acid, adipic acid, azelaic acid,
Examples thereof include trimellitic acid or acid anhydrides or ester-forming derivatives thereof. Of these polybasic acids,
An aromatic polybasic acid having excellent hydrolyzability is preferable, and it can be appropriately selected and used from the viewpoint of coating film performance.

The amount of the polybasic acid compounded is 40 to 70% by weight, especially 4% by weight, based on the total amount of the polyhydric alcohol component and the polybasic acid.
It is preferably 5 to 65% by weight. When the amount of the polybasic acid compounded is less than 40% by weight, the resin structure has a small molecular weight and a high hydroxyl value, and the hardness of the resulting coating film is excellent, but the physical properties tend to deteriorate and exceeds 70% by weight. If so, the molecular weight of the resin becomes large, and the particle diameter of the resulting water-dispersed resin composition becomes large, so that the dispersion stability tends to decrease.

In the present invention, the composition containing the above-mentioned polyhydric alcohol component and polybasic acid is heated and reacted as necessary to give an acid value (solid) of 10 to 40 and a hydroxyl value (solid) of 50. ~ 200, number average molecular weight 1000-500
0 oil-free alkyd resin is formed and used. The reaction temperature can be appropriately determined depending on the type of components used, and the reaction time is until the oil-free alkyd resin as described above is obtained.

Acid value (solid) of oil-free alkyd resin
Is 10 to 40, preferably 15 to 35. When the acid value (solid) is less than 10, the hydrophilicity after neutralization is low, the particle size of the resulting water-dispersed resin composition is large, and the dispersion stability is poor. On the other hand, when it exceeds 40, the hydrophilicity after neutralization is high, the viscosity of the obtained water-dispersed resin composition is high, and the coating solid content is reduced.

The oil-free alkyd resin is 50
It is necessary to have a hydroxyl value (solid) of 200 to 200, and it is preferable to have a hydroxyl value (solid) of 80 to 170. If the hydroxyl value is less than 50, the resulting coating film has a low crosslink density and the coating film performance is generally inferior. If it exceeds 200, the resulting coating film has a too high crosslink density and the physical properties are significantly deteriorated. ..

Further, the oil-free alkyd resin is 1
It is necessary to have a number average molecular weight of 000 to 5000, and it is preferable to have a number average molecular weight of 2000 to 4000. When the number average molecular weight is less than 1000, the cross-linking density of the obtained coating film becomes high and the physical properties are remarkably lowered, and when it exceeds 5,000, the smoothness of the obtained coating film is lowered and the water-dispersed resin composition The particle size of the product becomes large and the stability decreases.

The thermosetting water-dispersible resin composition of the present invention comprises the above oil-free alkyd resin, a water-soluble solvent,
It is formed by adding a neutralizing agent for neutralizing the carboxyl groups in the resin and water. Here, as the water-soluble solvent, ethanol, isopropanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, 3-methyl-3-methoxybutanol, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol methyl ether Acetate, DBE (DuPont, dibasic acid dimethyl ester), butyl carbitol and the like can be appropriately selected and used. As the neutralizing agent, amines such as ammonia, triethylamine and dimethylaminoethanol, alkali metal hydroxides such as sodium hydroxide and ammonium salts such as ammonium carbonate can be appropriately selected and used. The degree of neutralization is the pH of the composition
Is preferably 7 to 9. Neutralization can be carried out before or after addition of the water-soluble solvent.

A neutralizing agent is added to neutralize the carboxyl groups, and then water is added to disperse the resin in water to obtain a thermosetting water-dispersible resin composition having a desired solid content. Obtainable.

The thermosetting water-dispersible resin composition of the present invention obtained as described above exhibits water-dispersion stability, and by adding an amino resin as a curing agent to this composition, an excellent aqueous resin coating composition is obtained. Produces a composition for use.

The amino resin used at that time is obtained by subjecting an amino compound such as urea, melamine or benzoguanamine to an aldehyde such as formalin or paraformaldehyde, and then etherifying with a monoalcohol having 1 to 4 carbon atoms. Examples thereof include urea resins, melamine resins and the like, industrially, n-butyl etherified amino resins, isobutyl etherified amino resins, methyl etherified amino resins and the like. In particular, methyl etherified melamine resin is preferable because it is easily dissolved in water.

In the coating composition of the present invention, the mixing ratio of the water-dispersed resin composition and the amino resin is 95/5 to 6
It is preferably 0/40 (solid content weight ratio). When the ratio of the water-dispersed resin composition exceeds 95/5, the cross-linking density of the obtained coating film is low, and the coating film properties generally tend to be inferior. On the other hand, when it is less than 60/40, the cross-linking density of the obtained coating film becomes high, and the physical properties and interlayer adhesion are lowered.

In the coating composition of the present invention, an alkyd resin, an epoxy resin, a polyester resin, an acrylic resin, a blocked polyisocyanate resin or the like can be used in combination with the amino resin. To the coating composition of the present invention, a pigment, a dispersant, an anti-repellent agent and the like which are usually used can be appropriately added.

The coating composition of the present invention can be applied to the surface of plastics, ceramics, ferrous metals, non-ferrous metals, etc. by any method such as brush coating, dipping method, spray coating and roll coating.

[0027]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples, "parts" means "parts by weight" unless otherwise specified. In addition, the number average molecular weight was measured by weighing 150 mg of the sample, dissolving it in 5 ml of tetrahydrofuran, and then using high performance liquid chromatography [manufactured by Hitachi, Ltd., model 665A-11, column by Hitachi Chemical Co., Ltd., Gelpack R440, R450, R400
M is used], and a calibration curve of standard polystyrene is prepared and converted.

Example 1 In a 2 liter glass flask equipped with a stirrer, a thermometer, a dehydrator equipped with a rectification column and an inert gas introduction device, 50 parts of versatic acid glycidyl ester and 153.9 parts of trimethylolpropane were added. 2-Butyl-2-ethyl-1,3-propanediol 203.9 parts, 1,6-hexanediol 100 parts, polyoxyethylene glycol (molecular weight 4000, trade name PEG4000S, manufactured by Sanyo Chemical Industry Co., Ltd., and so on) ) 70 parts and isophthalic acid 57
Charge 6.2 parts and heat to 180 ° C. 220 in 3 hours
The temperature was raised to 0 ° C., the reaction was allowed to proceed at the same temperature until the acid value (solid) was 20, and the temperature was cooled to 150 ° C. Dilute with 250 parts of 3-methyl-3-methoxybutanol, then add 25.2 parts of triethylamine and mix evenly. The obtained resin was transferred to a 3 liter container and stirred with distilled water 122
By adding 5 parts little by little, an aqueous dispersion resin composition having an acid value (solid) of 20, a hydroxyl value (solid) of 110 and a number average molecular weight of 2300 was obtained.

Example 2 In a 2 liter glass flask equipped with a stirrer, a thermometer, a dehydrator equipped with a rectification column, and an inert gas introduction device, 50 parts of versatic acid glycidyl ester, and 200.2 parts of trimethylolpropane were added. 126.5 parts of 2-butyl-2-ethyl-1,3-propanediol, 100 parts of 1,6-hexanediol, 70 parts of polyoxyethylene glycol (molecular weight 4000) and 561.9 parts of isophthalic acid were charged, and the temperature was 180 ° C. Heat to. The temperature was raised to 220 ° C. in 3 hours, the reaction was allowed to proceed at the same temperature until the acid value (solid) reached 30, and the temperature was cooled to 150 ° C. Diluted with 250 parts of 3-methyl-3-methoxybutanol, then added 37.8 parts of triethylamine and mixed uniformly. The resin obtained is 3
It was transferred to a liter container, and 1225 parts of distilled water was added little by little with stirring to obtain an aqueous dispersion resin composition having an acid value (solid) of 30, a hydroxyl value (solid) of 110, and a number average molecular weight of 3400.

Example 3 In a 2 liter glass flask equipped with a stirrer, a thermometer, a dehydrator equipped with a rectification column, and an inert gas introduction device, 50 parts of versatic acid glycidyl ester and 132.9 parts of trimethylolpropane were added. 2-Butyl-2-ethyl-1,3-propanediol 208.8 parts, 1,6-hexanediol 100 parts, polyoxyethylene glycol (molecular weight 4000) 100 parts and isophthalic acid 508.5.
Charge parts and heat to 180 ° C. The temperature was raised to 220 ° C. in 3 hours, the reaction was allowed to proceed until the acid value (solid) reached 20 at the same temperature, and the temperature was cooled to 150 ° C. Dilute with 250 parts of 3-methyl-3-methoxybutanol, then add 25.2 parts of triethylamine and mix evenly. The resin obtained is 3
It was transferred to a liter container, and 1225 parts of distilled water was added little by little with stirring to obtain an aqueous dispersion resin composition having an acid value (solid) of 20, a hydroxyl value (solid) of 110, and a number average molecular weight of 2200.

Comparative Example 1 117.8 parts of trimethylolpropane and 234.2 parts of neopentyl glycol were placed in a 2 liter glass flask equipped with a stirrer, a thermometer, a dehydrator equipped with a rectification column and an inert gas introduction device. 1,6-hexanediol 10
0 parts, polyoxyethylene glycol (molecular weight 400
0) Charge 70 parts and 602.2 parts of isophthalic acid,
Heat to 0 ° C. The temperature was raised to 220 ° C. in 3 hours, the reaction was allowed to proceed until the acid value (solid) reached 20 at the same temperature, and the temperature was cooled to 150 ° C. 3-methyl-3-methoxybutanol 250
Dilute with 1 part, then add 25.2 parts triethylamine and mix evenly. The obtained resin was transferred to a 3 liter container, and 1225 parts of distilled water was added little by little with stirring to obtain an aqueous dispersion resin composition having an acid value (solid) of 20, a hydroxyl value (solid) of 110, and a number average molecular weight of 2000. Got

Comparative Example 2 150.0 parts of soybean oil fatty acid and 10 parts of dehydrated castor oil fatty acid were placed in a 2 liter glass flask equipped with a stirrer, a thermometer, a dehydrator equipped with a rectification column and an inert gas introduction device.
Charge 0.0 part, 41.9 parts of ethylene glycol, 289.0 parts of trimethylolpropane, 70 parts of polyoxyethylene glycol (molecular weight 4000) and 452.0 parts of isophthalic acid, and heat to 180 ° C. After keeping the same temperature for 2 hours,
The temperature was raised to 220 ° C in 2 hours and the acid value (solid) was 35 at the same temperature.
The reaction was allowed to proceed until, and cooled to 150 ° C. Dilute with 250 parts of 3-methyl-3-methoxybutanol, then add 44.1 parts of triethylamine and mix evenly. The obtained resin was transferred to a 3 liter container, and 1225 parts of distilled water was added little by little while stirring to obtain an acid value (solid) 35, a hydroxyl value (solid) 120, and a number average molecular weight of 22.
A water-dispersed resin composition of No. 00 was obtained.

Coating and Evaluation Each of the water-dispersed resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was made into a coating by the following formulation. Water dispersion resin composition (solid content 40%) 87.5 parts Titanium white (Taipec R-930 / Ishihara Sangyo Co., Ltd.) 100.0 parts 3-Methyl-3-methoxybutanol 5.0 parts Distilled water 10. 0 parts Glass beads 100.0 parts

2 μm of the above composition on a paint shaker
The mixture was dispersed until the following amount, and the following resins, additives and distilled water were added. Water-dispersed resin composition (solid content 40%) 100.0 parts Melan 620 (methyl etherified melamine resin / manufactured by Hitachi Chemical Co., Ltd., solid content 80%) 31.3 parts BYK302 (anti-repellent agent / Big Chemie Japan) Manufactured) 0.3 parts Distilled water Diluted in 40 seconds with Ford Cup # 4

The obtained coating material was applied to a Bonderite # 144 treated steel sheet (0.8t × 70 × 150 mm / manufactured by Nippon Test Panel Co., Ltd.) by air spraying so that the dry film thickness was 35 to 40 μm, and the coating was applied at 80 ° C. for 10 minutes. 14 after pre-drying
Baking at 0 ° C. for 30 minutes. A coating film test was conducted by the following method.

Coating Film Test (a) Gloss: 60 ° specular gloss was measured with a gloss meter manufactured by Suga Test Instruments Co., Ltd. (B) Erichsen: Measured with an Erichsen tester. (C) Impact value: 1/2 "-50 with DuPont impact tester
It was measured at 0 g and judged by the height (cm) at which the coating film did not crack. (D) Adhesiveness: 100 squares having a size of 1 × 1 mm were cut with a cutter, the coating film was peeled off with cellophane tape, and the peeled squares are shown. (E) Pencil hardness: Scratch hardness was measured with Mitsubishi Uni, manufactured by Mitsubishi Pencil Co., Ltd.

(F) Moisture resistance: The blister was subjected to A.V. after 72 hours of testing with a wetness tester manufactured by Suga Test Instruments Co., Ltd. S. T. It was judged by M judgment photograph. (G) Acid resistance: A 5% sulfuric acid aqueous solution was dropped onto the test plate in an amount of 0.5 cc, left at room temperature for 24 hours, wiped off, and the traces were visually evaluated according to the following criteria. ○: No traces △: Slight traces ×: Partially dissolved (h) Alkali resistance: 5% alkaline aqueous solution on the test plate.
After dropping 5 cc and leaving it at room temperature for 24 hours, wipe it off,
The traces were visually evaluated according to the following criteria. ○: No trace △: Slight trace ×: Partially dissolved

The formulations used in Examples 1 to 3 and Comparative Examples 1 and 2 and the properties of the resulting water-dispersed resin compositions are shown in Table 1.
Table 2 shows the performance of paints produced by using each water-dispersed resin composition.
It was shown to. The dispersion stability of the water-dispersed resin composition is 5
The viscosity is measured at 25 ° C. using a 0c / BH viscometer.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

The thermosetting water-dispersed resin composition of the present invention is
Excellent in water dispersion stability, the coating composition of the present invention using the same produces a coating film having excellent physical properties such as hardness and impact resistance and chemical resistance, and can be used for steel furniture, metal for automobiles, etc. It is most suitable as a water-based paint used for painting products.

Claims (3)

[Claims] 1. (A) 2-Butyl-2-ethyl-1,3
-Propanediol and (B) molecular weight 600-2000
Acid value (solid) 10 to 40, hydroxyl value (solid) 50 to 200 obtained by reacting polyhydric alcohol component containing 0 of polyoxyethylene glycol and polybasic acid,
Thermosetting water-dispersible resin obtained by adding a water-soluble solvent, a neutralizing agent for neutralizing a part or all of carboxyl groups in the resin, and water to an oil-free alkyd resin having a number average molecular weight of 1,000 to 5,000. Composition. 2. The oil-free alkyd resin comprises (A) component 10 to 40% by weight, (B) component 3 to 25% by weight, other polyhydric alcohol component 10 to 45% by weight, and polybasic acid 40 to 70% by weight. % Of the thermosetting water-dispersed resin composition according to claim 1. 3. A coating composition containing the thermosetting water-dispersed resin composition according to claim 1 or 2 and an amino resin.