JP3415170B2 - Method for producing water-soluble resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-soluble resin composition useful as a paint, an adhesive, a paper impregnating treatment agent, and the like.

[0002]

2. Description of the Related Art In recent years, coating and coating materials applied to automobiles, industrial machines, steel furniture, electric appliances, etc. have recently been required to save labor and energy. Furthermore, in recent years, in order to prevent air pollution due to organic solvents emitted from paints and adhesives, conventional solvent-based paints are being shifted to water-soluble paints.

In an aqueous paint containing an amino resin as a curing agent, a methyl etherified melamine resin is mainly used as the amino resin because of its water solubility. However, with a water-based paint using hexamethoxymethylol melamine, which is a typical methyl etherified melamine resin, a coating film having good flexibility can be obtained, but there is a problem of poor water resistance. In addition, the methyl etherified melamine resin containing a large amount of residual methylol groups has problems in stability of the coating and flexibility of the coating film.

On the other hand, the alkyl etherified benzoguanamine resin does not exhibit water solubility or water dispersibility, so that it is difficult to use it in an aqueous paint. The solution is
A method of improving water resistance and flexibility by using an amino compound composed of benzoguanamine and melamine has been proposed. For example, JP-A-59-147056 discloses an amino resin modified with an alcohol having a C ₃ or less in a melamine / benzoguanamine co-condensation system, having 1.5 or less methylol groups (per triazine nucleus), and An etherified amino resin in which the proportion of those having one triazine nucleus in one molecule is 40% or less is disclosed. When the coating material using the resin obtained by the above technique is used, the coating stability and sufficient coating performance can be obtained by baking at high temperature.
However, although a resin that can be baked at a low temperature has been demanded from the viewpoint of recent energy saving, there is a problem that sufficient coating film performance cannot be obtained under such a condition.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and enables low temperature baking, and the cured film thereof is a water-soluble resin composition excellent in water resistance, adhesion and flexibility. It is an object to provide a method for manufacturing a product.

[0006]

The present invention has achieved the above object by blending a specific methyl etherified amino resin.

The present invention comprises 5-60% by weight of melamine and
Amino composed of 95-40% by weight of nzoguanamine
0.5 or more per triazine nucleus for the compound
Formua so that no more than 1.5 imino groups are formed.
Addition of ludehyde and alcohol and the resulting mixture
Methylolation reaction by heating the material under alkaline conditions
And then under acidic conditions triazine in one molecule.
The proportion of those with only one core is 70% by weight or less
Heating until complete, carry out condensation and etherification reaction, and
Heat the solution under alkaline conditions to
Resin (A) to obtain the alkyl etherified amino resin
(A) and water-soluble or water-dispersible resin (B)
Mix (B) in a weight ratio of 5/95 to 60/40.
And a method for producing a water-soluble resin composition. The present invention
In addition, in the methylolation reaction, the amino compound 1
Formaldehyde to 3 to 10 moles, alcohol
The above-mentioned method of adding 5 to 30 mol of
The above-mentioned method in which the reaction is carried out under the alkaline condition of pH 9 to 11.
Method and condensation and etherification reaction with an acid of pH 2-4.
The above method performed under sex.

The present invention will be described in detail below. The alkyl etherified amino resin used as the component (A) in the method for producing a water-soluble resin composition of the present invention is obtained by subjecting an amino compound consisting of melamine and benzoguanamine to formaldehyde addition / condensation reaction and etherification reaction with alcohol. It is a resin. Melamine and benzoguanamine are used here as 5 to 60% by weight of melamine and 95 to 40% by weight of benzoguanamine. When the proportion of melamine is less than 5% by weight, the water solubility is lowered and the curing reactivity is lowered. On the other hand, when it exceeds 60% by weight, water resistance and flexibility are deteriorated.

The above addition / condensation reaction and etherification reaction with alcohol are carried out as follows. That is, melamine, benzoguanamine, formaldehyde and alcohol are mixed to make it alkaline (preferably pH).
9-11) under heating for methylolation reaction, then under acidic (preferably pH 2-4) for condensation and etherification reaction, mixing melamine, benzoguanamine, formaldehyde and alcohol or water , Heating under alkaline condition to cause methylolation reaction,
Isolation of the obtained amino resin, adding alcohol to this, heating under acidic conditions, methyl etherified benzoguanamine resin, mixing alcohols other than methanol, heating under acidic conditions and carrying out an ether exchange reaction, etc. is there. In such production, formaldehyde is used in an amount of 2.5 to 15 mol, alcohol to 5 to 30 mol, and preferably 5 to 20 mol, per 1 mol of melamine and benzoguanamine in total. When formaldehyde is less than 2.5 mol, the number of imino groups per triazine nucleus often exceeds 1.5. On the other hand, 1
If it exceeds 5 moles, the amount of unreacted formaldehyde also increases, and a large number of steps are required to finally remove it. From the reaction rate of formaldehyde, it is preferable to use 3 to 10 mol. If the amount of alcohol is less than 5 mol, the molecular weight increases drastically during the etherification reaction, increasing the viscosity,
It tends to gel. Further, if it exceeds 30 mol, the movement of the molecular weight at the time of etherification is slow, and it takes a long time for the ratio of mononuclear body to become 70% or less, and a great amount of labor is required when finally removing alcohol. Becomes In any case, the alkyl etherified amino resin of the component (A) in the present invention can be produced by appropriately adjusting the amounts of formaldehyde and alcohol used and the reaction conditions.

The alkyl etherified amino resin used in the present invention needs to have 0.5 to 1.5 imino groups per triazine nucleus. When the number of the imino groups exceeds 1.5, the stability of the water-based paint is lowered, the viscosity is increased, and the flexibility of the coating film is significantly lowered. On the other hand, water-soluble, for further coating properties (reactivity) represents an imino group Ru der 0.5 or more.

The number of formaldehyde per triazine nucleus is preferably 2 or more. If the number is less than 2, the stability during coating and the flexibility of the cured coating film tend to decrease.

Further, the alkyl etherified amino resin used in the present invention must have a proportion of mononuclear body (amino resin containing one triazine nucleus in one molecule) of 70% by weight or less. When this ratio exceeds 70% by weight, the reactivity at low temperature is lowered and the water resistance is also lowered. The ratio of mononuclear bodies is an area ratio in high performance liquid chromatography analysis. Also, if there are too few mononuclear bodies,
The water solubility and the solid content at the time of forming a coating material tend to decrease, and workability tends to deteriorate. Therefore, the proportion of mononuclear bodies is preferably 10% by weight or more.

A method for producing the water-soluble resin composition of the present invention
The water-soluble or water-dispersible resin used as the component (B) in the method is not particularly limited as long as it can react with the component (A) by heating, and examples thereof include a water-soluble or water-dispersible alkyd resin, a water-soluble or Examples include alkyd resins such as water-dispersible acrylic resins and neutralized products such as acrylic resins.

The above alkyd resin is, for example, an alkyd resin obtained by reacting a polyvalent carboxylic acid, a polyhydric alcohol and, if necessary, an oil or a fatty acid thereof.
Here, examples of the polycarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, maleic acid, fumaric acid, succinic acid, adipic acid, sebacic acid, trimellitic acid, and pyromellitic acid. They are,
It may be an acid anhydride or an ester-forming derivative such as methyl ester. As the polyhydric alcohol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol,
Neopentyl glycol, 1,4-butanediol,
1,6-hexanediol, trimethylene glycol,
Examples include glycerin, trimethylolpropane, trimethylolethane, and pentaerythritol. Examples of the oil include tung oil, linseed oil, soybean oil, dehydrated castor oil, safflower oil, castor oil, coconut oil and tall oil.

The alkyd resin can be produced by a known method. When an oil is used, the oil and the polyhydric alcohol are reacted at 200 to 260 ° C. in the presence of a transesterification catalyst such as lithium hydroxide. After that, a method of adding a polybasic acid and the remaining polyhydric alcohol and reacting at 180 to 250 ° C., when oil is not used, the raw materials are mixed to be 180 to 2
There is a method of reacting at 50 ° C.

The acrylic resin includes α, β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, and 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and methacrylic acid. It is obtained by copolymerizing an α, β-ethylenically unsaturated monomer having a hydroxyl group such as 2-hydroxyethyl and 2-hydroxypropyl methacrylate, and another unsaturated monomer. Other unsaturated monomers include α, β-monoethylenically unsaturated compounds such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate and n-butyl methacrylate. Alkyl ester of carboxylic acid, acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, acrylamide derivative such as diacetone acrylamide, α, β-monoethylenically unsaturated carboxylic acid such as glycidyl acrylate, glycidyl methacrylate Glycidyl ester of
Examples thereof include vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate, and araliphatic unsaturated monomers such as styrene, α-methylstyrene and vinyltoluene.

The above copolymerization is carried out in the presence of a radical catalyst such as azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, cumene hydroperoxide, etc.
It can be performed by heating to 0 ° C.

The alkyd resin and acrylic resin are preferably adjusted to have an acid value of 20 to 100 and a hydroxyl value of 15 to 200. If the acid value is too small, the water solubility or water dispersibility after neutralization will be poor, and if the acid value is too large, the coating properties will tend to deteriorate. Further, if the hydroxyl value is too small, the curability is poor, and if the hydroxyl value is too large, the water resistance of the coating film is poor.

When making such an alkyd resin and an acrylic resin water-soluble or water-dispersible, the acid groups of the resin may be neutralized with a volatile base such as ammonia or amine. , For example, primary, secondary and tertiary of monopropylamine, monobutylamine, diethylamine, dibutylamine, triethylamine, tributylamine, monoethanolamine, ethylmonoethanolamine, monocyclohexylamine, morpholine, piperidine, etc. Aliphatic or alicyclic amines are mentioned. Ammonia and amine are preferably used in an amount of 0.3 to 1.2 mol per equivalent of acid group.

In the present invention, the alkyl etherified amino resin as the component (A) and the water-soluble or water-dispersible resin as the component (B) have a weight ratio of (A) / (B) of 5 / 95-60 /.
It is blended to be 40. When the proportion of the amino resin is less than 5% by weight, the curing reactivity is lowered, and when it exceeds 60% by weight, the flexibility of the coating film is lowered.

An acid catalyst such as hydrochloric acid, phosphoric acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid may be added to the water-soluble resin composition obtained by the production method of the present invention. The amount of the acid catalyst used is preferably 1% by weight or less based on the component (A).

The water-soluble resin composition obtained by the production method of the present invention is butyl cellosolve, ethyl cellosolve, diacetone alcohol, 3-methoxy-3-methylbutane-1.
-Used after diluting to an appropriate solid content with a mixed solvent of water and a water-soluble solvent such as all, isopropanol, and methanol.

Pigments and other additives can be further added to the water-soluble resin composition obtained by the production method of the present invention depending on the purpose. Also, as a painting method,
Spray coating, roll coater coating, dip coating,
Spin coating or the like can be adopted.

[0024]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Production Example 1 80 in a flask equipped with a stirrer, a reflux condenser and a thermometer.
% Paraformaldehyde 187.5 g, methanol 48
After adding 0.0 g and 0.3 g of 50% aqueous sodium hydroxide solution and dissolving paraformaldehyde at 40 ° C., 130.9 g of benzoguanamine and 37.8 g of melamine were added, and addition reaction was carried out at 60 ° C. for 3 hours. Then 62
% 1.3% nitric acid, and under acidic condition at 60 ℃ for 2 hours 30
It was made to react for minutes. After the reaction was completed, 1.5 g of 50% aqueous sodium hydroxide solution was added again to make the reaction solution alkaline, and the solution was concentrated under reduced pressure (50 torr). The end point was when the temperature inside the flask reached 130 ° C. At the same time as the end point, 130 g of butyl cellosolve was added, and the heating residue was adjusted to 70% by weight. The amount of methyl etherified amino resin produced was about 430 g and the viscosity was Z Gardner viscosity.

Production Examples 2 to 7 Using the same apparatus as in Production Example 1, the amounts of formaldehyde, methanol, benzoguanamine and melamine were changed,
A methyl etherified amino resin was synthesized under the same conditions as in Example 1. Table 1 shows the formulation, diluted butyl cellosolve, the amount of resin produced and the viscosity in each Production Example.

[0027]

[Table 1]

The results of analysis of the number of imino groups and methyl ether groups per triazine nucleus and the content of mononuclear bodies of the methyl etherified amino resin obtained in the above Production Example are shown in Table 2. The number of imino groups and methyl ether groups per triazine is ¹ H-N
It was calculated by MR and mass balance at the time of synthesis.

The content of mononuclear bodies was determined by the area ratio from the chromatogram obtained by high performance liquid chromatography. The elution time of one nucleus is about 32 minutes, the elution time of one nucleus is about 30.5 minutes, and that of three or more nucleotides is about 30.5 minutes or less. The measurement conditions of high performance liquid chromatography are as follows.

Column: Three kinds of porous styrene-divinylbenzene resin particles [manufactured by Hitachi Chemical Co., Ltd., trade name G
ELKO GL-410, 420, 430, theoretical plate number 1
7,000 columns / piece], three columns with an inner diameter of 8 mm and a length of 25 cm connected in series. Solvent; Tetrahydrofuran flow rate; 1.75 ml / min Sample concentration; 100 mg / 5 ml tetrahydrofuran injection volume; 50 μl Detector; Differential refractometer

[0031]

[Table 2]

Examples 1 to 4 and Comparative Examples 1 to 3 The methyl etherified amino resin obtained in the above Production Example, a water-soluble acrylic resin having a hydroxyl value of 27.5 (Hitaroid 7121, manufactured by Hitachi Chemical Co., Ltd., solid) 50% by weight, solvent: water / isopropanol) and titanium white were mixed in the composition (unit, parts by weight) shown in Table 3 and kneaded with a roll, and then thinner (composition: butyl cellosolve / water = 50/50) was added. After adjusting the viscosity with Ford Cup # 4 for 20 seconds (25 ° C.), spray coating to obtain a film thickness of 30-40 μm (Bondelite # 144)
And leave it at room temperature for about 20 minutes and then at 140 ° C for 2 minutes.
Bake for 0 minutes.

[0033]

[Table 3]

The performance of the obtained coating film was measured by the following method, and the results are shown in Table 4. (1) Gloss: Measured by 60 ° specular reflectance. (2) Pencil hardness: Determined by Mitsubishi Pencil Uni. (3) Cross-cut: The coating film surface was cut into 100 squares with a cutter knife at 1 mm intervals, and judged by the number of squares left when peeled off with cellophane tape. (4) Erichsen value: Tested according to JIS-K5400. (5) Impact value: Judgment was made in centimeters by a DuPont type impactor 1/2 ″ -500 g. (6) Boiling water resistance: After soaking in boiling water for 1 hour, the film was taken out and the appearance of the coating film was visually judged based on the following criteria. ○ ・ ・ ・ No change △ ・ ・ ・ Slightly corroded × ・ ・ ・ Strongly corroded (6) Magic stain resistance: Write characters on the coating surface with the magic ink red, leave it at room temperature for 24 hours, and then with butanol. Was wiped, and the state was visually judged based on the following criteria. ◯: It was wiped off cleanly △: A little magic ink remained (7) Acid resistance: It was immersed in a 1N acetic acid solution at 40 ° C for 4 hours and then taken out, and the appearance of the coating film was visually judged according to the following criteria. did. ○ ・ ・ ・ No change △ ・ ・ ・ Slightly invaded × ・ ・ ・ Very violent

[0035]

[Table 4]

[0036]

The water-soluble resin composition obtained by the production method of the present invention can be baked at a low temperature and is excellent in adhesion, hardness, impact resistance, stain resistance, acid resistance, water resistance and flexibility. Produces a coating film.

Continuation of the front page (56) Reference JP 59-147056 (JP, A) JP 53-61628 (JP, A) JP 4-136078 (JP, A) JP 5-65452 (JP , A) JP 63-12670 (JP, A) JP 1-301768 (JP, A) JP 59-184265 (JP, A) JP 62-101666 (JP, A) JP 3-115377 (JP, A) JP 62-207373 (JP, A) JP 2-300272 (JP, A) JP 2-29478 (JP, A) JP 47-1393 (JP, B1) JP-B 49-6552 (JP, B1) JP-B 49-6545 (JP, B1) JP-B 46-12627 (JP, B1) JETI (Japan Energy & Technology Intelligence), February 1992 40, [2], 1992), p. 94-99 (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 61/20-61/32 C08G 12/00-12/46 C09D 161/20-161/32 CA (STN) REGISTRY (STN ) JIST file (JOIS)

Claims (4)

(57) [Claims] 1. Melamine 5 to 60% by weight and benzogua
An amino compound composed of 95-40% by weight of namin
On the other hand, 0.5 to 1.5 per triazine nucleus
So that the lower imino group is formed, formaldehyde and
Alkali of the addition of the alcohol and the mixture obtained by the addition
And heating under acidic conditions to induce the methylolation reaction.
And then, under acidic conditions, only one triazine nucleus per molecule
Heat until the proportion of what you have is less than 70% by weight
To carry out condensation and etherification reactions, and then heat under alkaline conditions to give alkyl etherification
Mino resin (A) is obtained, and the alkyl etherified amino resin is obtained.
The fat (A) and the water-soluble or water-dispersible resin (B),
/ (B) should be 5 / 95-60 / 40 in weight ratio
A method for producing a water-soluble resin composition, which comprises mixing. 2. In the methylolation reaction, the
The above formaldehyde is added to 3 mol per mol of the mino compound.
-10 mol, 5-30 mol of the alcohol is added,
The method for producing the water-soluble resin composition according to claim 1. 3. The methylolation reaction is performed at pH 9-11.
The water solution according to claim 1 or 2, which is carried out under alkaline condition.
For producing a water-soluble resin composition. 4. The condensation and etherification reactions are conducted at pH 2
4. Carrying out under acidic conditions of -4, any one of Claims 1-3.
The method for producing the water-soluble resin composition according to item 1.