JP3203714B2 - Water-dispersed resin composition and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-dispersible resin composition containing a melamine-modified epoxy acrylic resin useful for paints, adhesives and the like, and a method for producing the same .

[0002]

2. Description of the Related Art In recent years, there has been a high demand for labor and energy savings for coatings and adhesives for coating automobiles, steel furniture, electric appliances and the like. Further, in order to prevent air pollution caused by organic solvents radiated from the paint, the transition from the conventional organic solvent type paint to the aqueous paint is progressing. However, with water-based paint, baking can be performed for a short time, and the water resistance, adhesion,
At present, a material having an excellent balance of flexibility has not been found.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, is capable of baking for a short time, and has a cured film having a melamine-modified coating excellent in water resistance, adhesion and flexibility. A water-dispersed resin composition containing an epoxy acrylic resin ; and
An object of the present invention is to provide a method for producing the same.

[0004]

The present invention provides (A) and (a)
An aromatic epoxy resin having a number average molecular weight in the range of 4500 to 8000, and (b) melamine and / or benzoguar
A melamine resin, a benzoguanamine resin, or a melamine / benzoguanamine co-condensation resin obtained by adding an aldehyde to namin and alkyl-etherifying with an alcohol having 1 to 4 carbon atoms is used to give a weight ratio of (a) / (b) of 95/5. ~ 60 /
Modified epoxy resin 9 reacted at a ratio in the range of 40
(B) a carboxyl-functional acrylic having an acid value of 100 to 350;
10-50 parts by weight of partially neutralized acrylic resin Le resin with ammonia or amine (solids) (where the total amount [(A) + (B)] as 100 parts by weight) and reacting the with melamine modified Manufacturing epoxy acrylic resin
Characterized by a melamine-modified epoxy acrylic resin and
Including a diluent consisting of a mixed solvent of a water-soluble organic solvent and water
And a method for producing a water-dispersed resin composition . Further, the present invention relates to (A) and (a) having a number average molecular weight of 45.
A melamine resin, a benzoguanamine resin or a melamine / benzoguanamine obtained by adding an aldehyde to an aromatic epoxy resin in the range of from 00 to 8000 and (b) melamine and / or benzoguanamine and alkylating it with an alcohol having 1 to 4 carbon atoms; (A)
/ Modified epoxy resin 90 to 50 parts by weight obtained by reacting a proportion in the range of 95 / 5-60 / 40 by weight ratio of (b) (solid content) and (B) a carboxyl functional acid number 100 to 350 acrylate
To 50 to 50 parts by weight (solid content) of an acrylic resin partially neutralized with ammonia or an amine, provided that the total amount ((A) + (B)] is 100 parts by weight). A water-dispersible resin composition comprising a melamine-modified epoxy acrylic resin and a diluent comprising a mixed solvent of a water-soluble organic solvent and water.

Hereinafter, the present invention will be described in detail. In the present invention, the aromatic epoxy resin (a) used for producing the resin as the component (A) has a number average molecular weight in the range of 4,500 to 8,000. When the number average molecular weight is less than 4500, the processability and adhesion of the cured coating film of the final resin composition are reduced. On the other hand, when the number average molecular weight exceeds 8000, gelation is likely to occur during the reaction with the component (b), and When the obtained component (A) is allowed to react with the component (B), it is easily gelled,
Stability decreases as viscosity increases when used as a paint,
It becomes difficult to handle in work. From the viewpoint of these characteristics, (a)
The number average molecular weight of the aromatic epoxy resin is 5500 to 75.
00 is preferable, and 6000 to 7000 is more preferable.

Although there is no limitation on the method for producing such an epoxy resin, for example, D-Chemicals sold by Dow Chemical Company
It can be easily produced by using ER343 (diglycidyl ether of bisphenol A, trade name) and bisphenol A.

(A) As described above, the aromatic epoxy resin can be synthesized from, for example, bisphenol A and DER343 (trade name of diglycidyl ether of bisphenol A) commercially available from Dow Chemical Company. In this case, the weight ratio of bisphenol A / DER343 is preferably set to 35 to 32/65 to 68 from the viewpoint of controlling the molecular weight. Bisphenol A and DER343
Is preferably performed at a reaction temperature of 180 to 190 ° C. If the reaction temperature is lower than 180 ° C., it takes a long time to obtain the final target molecular weight, the content of low molecular components is increased, and the curability of the final product tends to decrease.
On the other hand, when the temperature exceeds 190 ° C., the reaction proceeds rapidly, and the control tends to be difficult.

Further, in the present invention, a melamine resin, a benzoguanamine resin or a melamine obtained by adding the aldehyde of the component (b) and alkyl-etherifying with an alcohol having 1 to 4 carbon atoms, which is used for the production of the resin of the component (A). The melamine resin, the benzoguanamine resin and the melamine / benzoguanamine cocondensation resin in the benzo / guanguanamine cocondensation resin are prepared by first adding an aldehyde such as formaldehyde and paraformaldehyde, and then having 1 to 4 carbon atoms.
Is a resin alkyl etherified with the alcohol of
The production method is not particularly limited.

For example, there is a method in which formaldehyde, methanol, melamine (and / or benzoguanamine) are first mixed, heated under alkaline conditions (preferably at pH 9 to 11), and etherified and condensed. Also,
By another method, melamine (and / or benzoguanamine), formaldehyde, methanol and water are mixed, heated under alkaline conditions, and subjected to an addition reaction to isolate methylolated melamine (and / or benzoguanamine) obtained. In addition, there is a method in which n-butanol is added thereto, and the mixture is heated and reacted under an acidic condition to carry out an etherification and condensation reaction.

In carrying out such a production method, 4 to 20 mol of formaldehyde and 5 to 30 mol of an alcohol having 1 to 4 carbon atoms are used per 1 mol of melamine (and / or benzoguanamine). Is preferred.

In the present invention, a melamine resin, a benzoguanamine, which is obtained by adding (a) the aromatic epoxy resin as described above and (b) alkylating with an alcohol having 1 to 4 carbon atoms by adding an aldehyde as described above. Resin or melamine / benzoguanamine co-condensation resin
The modified epoxy resin reacted at a weight ratio of (b) of 95/5 to 60/40 is used as the component (A). In this reaction, the component (b) is added to the (a) aromatic epoxy resin kept at 80 to 130 ° C, and the reaction is performed at 80 to 110 ° C for 10 minutes to 5 hours, preferably 30 minutes to 2 hours, and more preferably. Can be carried out by keeping the temperature for 1 to 2 hours. The end point of the reaction can be controlled by analyzing the oxirane content (%), etc., but the molecular weight is measured, and the low molecular weight compound (number average molecular weight of 1200 or less) is 2 to 20% by weight, preferably 5 to 10% by weight. % By selecting the reaction temperature and time.

The weight ratio of component (a) / component (b) is in the range of 95/5 to 60/40 as described above. (A)
The more components, the worse the stability of the final paint. When the amount of the component (b) increases, gelation easily occurs during the above-mentioned reaction step, and the workability and corrosion resistance of the coating film are significantly reduced.

The number average molecular weight of the modified epoxy resin (A) thus obtained is preferably in the range of 3,000 to 10,000.

In the present invention, an acrylic resin having an acid value of 100 to 350 obtained by partially neutralizing a carboxyl-functional polymer with ammonia or an amine is reacted as the component (A) with the component (A). The carboxyl-functional polymer used herein includes α, β-monoethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid. 2-hydroxyethyl methacrylate, mosquito obtained α having a hydroxyl group such as 2-hydroxypropyl methacrylate, beta-ethylenically unsaturated monomer and other unsaturated monomer, etc. are copolymerized
It is a ruboxyl functional acrylic resin.

[0015] Other unsaturated monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate,
2-ethylhexyl acrylate, methyl methacrylate,
Alkyl esters of α, β-monoethylenically unsaturated carboxylic acids such as n-butyl methacrylate, acrylamide,
Methacrylamide, N-methylolacrylamide, N
-Acrylamide derivatives such as methylol methacrylamide and diacetone acrylamide; glycidyl esters of α, β-monoethylenically unsaturated carboxylic acids such as glycidyl methacrylate and glycidyl methacrylate; vinyls of saturated carboxylic acids such as vinyl acetate and vinyl propionate. There are aromatic unsaturated monomers such as esters, styrene, α-methylstyrene, and vinyl toluene.

The copolymerization is carried out by heating to 130 to 160 ° C. in the presence of a radical catalyst such as azobisisobutyronitrile, t-butylperoxybenzoate, benzoyl peroxide, dibutyl peroxide, cumene hydroperoxide. It can be carried out.

The carboxyl-functional polymer (acrylic resin before neutralization) used in the present invention is adjusted to have an acid value of 100 to 350, and preferably has an acid value of 200 to 320. When the acid value is less than 100, the water-dispersibility or water-dispersibility of the water-dispersible resin composition is poor, and the stability of the paint is poor.
On the other hand, when the acid value exceeds 350, the properties of the coating film (particularly, hot water resistance) deteriorate. It is easy to gel when the component (A) and the component (B) react.

The carboxyl-functional polymer preferably has a number average molecular weight of 5,000 to 12,000,
More preferably, it is 7000 to 11000. If the number average molecular weight is less than 5,000, hot water resistance and processability decrease, and if it exceeds 12,000, the viscosity of the final product increases, which is not preferable.

In the present invention, the acid groups of the resin are neutralized with a volatile base such as ammonia or amine to make the carboxyl-functional polymer water-soluble or water-dispersible. Preferred amines here include monopropylamine, monobutylamine, diethylamine, dibutylamine, triethylamine, tributylamine, monoethanolamine, ethyl monoethanolamine, monocyclohexylamine, dimethylaminoethanol, 2-amino-2-methyl- Primary, secondary and tertiary aliphatic or cycloaliphatic amines such as 1-propanol, morpholine, piperidine and the like. Ammonia or amine is preferably used in an amount of 0.6 to 1.0 mol per 1 mol of the acid group. If the amount of ammonia or amine is less than 0.6 mol, water dispersibility or water solubility tends to be insufficient, and if it exceeds 1.0 mol, the viscosity of the final product tends to be too high.

The acrylic resin (B) obtained by partially neutralizing the carboxyl-functional polymer preferably has a number average molecular weight of 5,000 to 12,000, and an acid value of 100 to 350. Preferably, there is.

The melamine-modified epoxy compound according to the present invention
The amount of the above-mentioned (A) component is from 90 to 50 parts by weight (solid content) and the amount of the (B) component is from 10 to 50 parts by weight (solid content), and the total amount thereof is 100 parts by weight. And reacted. The reaction between the component (A) and the component (B) is performed at 60 to 130 ° C, preferably 70 to 100 ° C.
° C, more preferably 75 to 85 ° C for 5 minutes to 5 hours, preferably 10 minutes to 1 hour, more preferably 20 minutes to
The reaction can be performed under a reaction condition of 40 minutes. The end point of the reaction is controlled by an acid value (in terms of solid content) of 25 to 45, preferably 3 to 45.
It is desirable to carry out by selecting the reaction conditions so as to be 0 to 40. When the amount of the component (A) exceeds 90 parts by weight, water dispersibility and curability are inferior. When the amount is less than 50 parts by weight, flexibility, water resistance and adhesion are inferior, and gelation is liable to occur.

The melamine-modified epoxy acrylic resin of the present invention
A catalyst such as an inorganic acid such as hydrochloric acid or phosphoric acid or an organic acid such as p-toluenesulfonic acid may be added to the fat . The amount of use is preferably 1 part by weight or less based on 100 parts by weight of the component (A) + (B) (solid content).

The melamine-modified epoxy acrylic resin of the present invention
Fats are butyl cellosolve, ethyl cellosolve, methyl cellosolve, diacetone alcohol, 3-methoxy-3-
Dilute a mixed solvent of water and a water-soluble organic solvent such as methylbutan-1-ol, isopropanol, ethanol, methanol and the like as a diluent to obtain an appropriate solid content and disperse in water.
It can be used as a resin composition . The ratio of water / organic solvent (weight ratio) is preferably from 95/5 to 80/20. This diluent has a solid content of 30 in the water-dispersed resin composition.
It is preferable to use the compound in such an amount that the viscosity becomes 150 to 2000 cps at the time of weight%.

[0024]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Production Example 1 (Production of Partially Neutralized Acrylic Resin) A flask equipped with a stirrer, a reflux condenser, a thermometer and an inert gas inlet was charged with 35 parts by weight of butyl cellosolve and 20 parts by weight of butanol, and heated. The temperature was raised to 130 ° C., and 28 parts by weight of styrene and 26 parts of ethyl acrylate were added.
A mixed solution consisting of parts by weight, 46 parts by weight of methacrylic acid and 0.6 parts by weight of t-butylperoxybenzoate was added dropwise over 3 hours. Thereafter, 5 parts by weight of butyl cellosolve and 23 parts by weight of butanol were added dropwise over 20 minutes, and the mixture was kept warm for 2 hours to obtain a carboxyl-functional polymer (acid value: 300, solid content conversion).

Thereafter, the mixture is cooled to 100 ° C., 47 parts by weight of water are added, and dimethylaminoethanol 3 is added at 80 ° C.
One part by weight was added to obtain a partially neutralized acrylic resin (neutralization rate 65%). Then, water was added so that the heating residue was adjusted to 43% by weight (108 ° C., 3 hours). The resulting acrylic resin had an acid value of 300 (in terms of solid content), a number average molecular weight of 9,700 and a weight average molecular weight of 242.
00.

Production Example 2 (Production of Partially Neutralized Acrylic Resin) In a flask equipped with a stirrer, a reflux condenser, a thermometer and an inert gas inlet, 35 parts by weight of butyl cellosolve and 20 parts by weight of butanol were charged and heated. The temperature was raised to 130 ° C, and 32 parts by weight of styrene and 30 parts of ethyl acrylate were added.
A mixed solution consisting of 38 parts by weight of methacrylic acid and 0.6 part by weight of t-butylperoxybenzoate was added dropwise over 3 hours. Thereafter, 5 parts by weight of butyl cellosolve and 23 parts by weight of butanol were added dropwise over 20 minutes, followed by keeping the temperature for 2 hours to obtain a carboxyl-functional polymer (acid value 250, solid content conversion).

Thereafter, the mixture is cooled to 100 ° C., 47 parts by weight of water are added, and further, dimethylaminoethanol 2 is added at 80 ° C.
3.6 parts by weight were added to obtain a partially neutralized acrylic resin (neutralization rate 65%). Then, water was added to adjust the heating residue to 43% by weight. The acid value of the obtained acrylic resin was 250 (in terms of solid content), and the number average molecular weight was 9
The weight average molecular weight was 600.

Production Example 3 (Production of Aromatic Epoxy Resin) 405 parts by weight of a glycidyl ether type epoxy resin of bisphenol A (trade name: DER343, manufactured by Dow Chemical Company) and 220 g of bisphenol were weighed, and a stirrer was used.
The flask was charged with a reflux condenser, a thermometer, and an inert gas inlet. The heating was adjusted to 130 ° C. in about 30 minutes, and then the heating was stopped and the reaction heat was used to reduce the temperature to 19 ° C.
The temperature was raised to 0 ° C. The reaction was carried out at this temperature for 2 hours to obtain an aromatic epoxy resin. Number average molecular weight (Mn) of this resin
Was 6550, the weight average molecular weight (Mw) was 19,600, and the degree of dispersion (Mw / Mn) was 2.99.

Production Example 4 (Production of Aromatic Epoxy Resin) An aromatic epoxy resin was synthesized in the same manner as in Production Example 3 except that the amount of bisphenol was changed to 209 parts by weight. The number average molecular weight (Mn) of this resin is 4760, the weight average molecular weight (Mw) is 11750, and the degree of dispersion (Mw / Mw)
n) was 2.5.

Production Example 5 (Production of Melamine Resin) 225 g of paraformaldehyde, 444 g of n-butanol and 126 g of melamine were weighed into a flask equipped with a stirrer, a reflux condenser and a thermometer, and subjected to an addition reaction at 90 ° C. for 30 minutes. Then, 0.1 g of phthalic acid was added, and the mixture was reacted for 2 hours while refluxing and dehydrating under acidic conditions, thereby performing alkyl etherification. After completion of the reaction, the mixture was heated and concentrated, and the obtained resin was diluted with butanol to adjust the solid content to 74.8% by weight. The viscosity of this product, Y ^- (Gardner / 25 ° C.)
Met.

Production Example 6 (Production of melamine / benzoguanamine co-condensation resin) In a flask equipped with a stirrer, a reflux condenser and a thermometer, 187.5 g of paraformaldehyde and 370 n-butanol were added.
g, 63 g of melamine and 93.5 g of benzoguanamine were weighed and subjected to an addition reaction at 90 ° C. for 30 minutes. Thereafter, 0.1 g of phthalic acid was added, and the mixture was refluxed and dehydrated under acidic conditions.
Reaction was carried out for an hour to effect alkyl etherification. After completion of the reaction, the mixture was heated and concentrated, and the obtained resin was diluted with butanol to adjust the solid content to 96.0% by weight. Its viscosity was Z ²⁻ (Gardner / 25 ° C.).

Production Example 7 (Production of Melamine Resin) 300 g of paraformaldehyde, 384 g of methanol and 126 g of melamine were weighed into a flask equipped with a stirrer, a reflux condenser and a thermometer, and subjected to an addition reaction at 90 ° C. for 30 minutes. 0.1 g of phthalic acid was added, and the mixture was reacted for 2 hours while performing dehydration under reflux under acidic conditions to carry out alkyl etherification. After completion of the reaction, the mixture was concentrated by heating, and the obtained resin was diluted with methanol to adjust the solid content to 71.8% by weight. The viscosity of this product, Z ^- was (Gardner / 25 ° C.).

Example 1 To 625 parts by weight of the epoxy resin obtained in Production Example 3 was added 50 parts by weight of butanol at 130 ° C., and the mixture was thoroughly stirred.
While maintaining the temperature at 30 ° C., 192.5 parts by weight of the melamine resin synthesized in Production Example 5 was added and reacted for 2 hours to obtain a modified epoxy resin (a low-molecular-weight product of this modified epoxy resin (number-average molecular weight of 1200 or less) was 7%). Wt%). 100 ℃
At that point, 447 parts by weight of the partially neutralized acrylic resin produced in Production Example 1 was added over 20 minutes (epoxy resin / melamine resin / acrylic resin = 65/15/20; solids content ratio by weight). The mixture was stirred and reacted at 80 ° C. for 30 minutes to obtain a melamine-modified epoxy acrylic resin. At this time, the acid value (in terms of solid content) was 40. Then 13
50 parts by weight of water was added over 1 hour to obtain a white water-dispersed resin composition, which was further adjusted to a solid content of 30.5% by weight with water. At this time, the acid value (in terms of solid content) was 39, the viscosity was 100 cps (B-type viscosity: 6 rpm) (organic solvent / water = 11/89), and the pH was 7.6.

Comparative Example 1 625 parts by weight of the epoxy resin obtained in Production Example 3 was cooled to 130 ° C., 50 parts by weight of butanol was added, and the mixture was sufficiently stirred. 782.6 parts by weight of a partially neutralized acrylic resin were added (epoxy resin / acrylic resin = 65/35; solid content weight ratio). Thereafter, the mixture was reacted by stirring at 80 ° C. for 30 minutes to obtain an epoxy acrylic reactant. The acid value at this time was 45. Thereafter, 1100 parts by weight of water was added over 1 hour to obtain a white water-dispersed resin composition, which was further adjusted to a solid content of 30% by weight with water. The viscosity at this time is 450 cps (B-type viscosity 6
rpm) (organic solvent / water = 13/87).

Examples 2 to 6 and Comparative Example 2 Resins were produced in the same manner as in Example 1 according to the formulations shown in Table 1 below to obtain water-dispersed resin compositions.

[0037]

[Table 1]

The characteristic values of the modified epoxy resins, melamine-modified epoxy acrylic resins, and water-dispersed resin compositions obtained in Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 2 below. The stability was evaluated by measuring the change in viscosity and the appearance after standing at room temperature (25 ° C.) for 60 days.

[0039]

[Table 2]

Coating film test A solid content of 30 obtained in Examples 1-6 and Comparative Examples 1-2.
The water-dispersed resin composition adjusted to% by weight was applied to a tin plate with a bar coater # 18 (the film thickness was 5 to 7 μm after baking). 200, 220, 270
Each was baked at 30 ° C. for 30 seconds. Then, it was left at room temperature for 24 hours, and the coating film test was measured by the following method.

Pencil hardness was evaluated according to JIS-K5400 using Mitsubishi Uni. Impact value Judged by a DuPont impactor 1/2 "-500. Retort resistance 130 ° C., immersed in steam at 2 atm, taken out, and evaluated for its appearance Adhesion after retort resistance test 130 ° C. After immersion at 2 atm, cut 100 pieces of 1mm x 1mm gobang on the coating film and perform peeling test with cellophane tape.
The rate of the peeling was determined. Erichsen value after retort resistance test After immersion at 130 ° C. and 2 atm, an Erichsen test was performed.
mm, and the appearance of the coating film was observed.

[0042]

[Table 3]

As is clear from the results shown in Table 3, the water-dispersed resin composition using the melamine-modified epoxy acrylic resin obtained by the production method of the present invention can be baked at a high temperature for a short time, and the resulting coating composition The film is excellent in water resistance, adhesion and flexibility.

[0044]

The water-dispersed resin composition using the melamine-modified epoxy acrylic resin obtained by the production method of the present invention has excellent stability and good curability which can be baked at a high temperature for a short time. , Resulting in a cured coating film having excellent water resistance, adhesion and flexibility.

Continuation of front page (56) References JP-A-5-17556 (JP, A) JP-A-4-283217 (JP, A) JP-A-2-212570 (JP, A) JP-A-4-168176 (JP) JP-A-2-286736 (JP, A) JP-A-58-79010 (JP, A) JP-A-56-131622 (JP, A) JP-A-55-145717 (JP, A) 52-36132 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/14-59/17 C09D 163/00-163/10 C09J 163/00-163/10

Claims (2)

(57) [Claims] (1) (A) (a) the number average molecular weight is 4500
Aromatic in the range of 8000 epoxy resin and (b) main
(A) / (b) a melamine resin, a benzoguanamine resin or a melamine / benzoguanamine co-condensation resin obtained by adding an aldehyde to lamin and / or benzoguanamine and alkyl-etherifying with an alcohol having 1 to 4 carbon atoms;
90 to 50 parts by weight (solid content) of a modified epoxy resin reacted at a weight ratio of 95/5 to 60/40
And (B) a carboxyl-functional acrylic having an acid value of 100 to 350
10-50 parts by weight of partially neutralized acrylic resin Le resin with ammonia or amine (solids) (where the total amount [(A) + (B)] as 100 parts by weight) and reacting the with melamine modified Manufacturing epoxy acrylic resin
Characterized by a melamine-modified epoxy acrylic resin and
Including a diluent consisting of a mixed solvent of a water-soluble organic solvent and water
A method for producing a water-dispersed resin composition comprising: 2. (A) (a) The number average molecular weight is 4500
Aromatic in the range of 8000 epoxy resin and (b) main
(A) / (b) a melamine resin, a benzoguanamine resin or a melamine / benzoguanamine co-condensation resin obtained by adding an aldehyde to lamin and / or benzoguanamine and alkyl-etherifying with an alcohol having 1 to 4 carbon atoms;
90 to 50 parts by weight (solid content) of a modified epoxy resin reacted at a weight ratio of 95/5 to 60/40
And (B) a carboxyl-functional acrylic having an acid value of 100 to 350
To 50 to 50 parts by weight (solid content) of an acrylic resin partially neutralized with ammonia or an amine, provided that the total amount ((A) + (B)] is 100 parts by weight). A water-dispersible resin composition comprising a melamine-modified epoxy acrylic resin and a diluent comprising a mixed solvent of a water-soluble organic solvent and water.