JPH01292073A - Resin composition for aqueous coating - Google Patents

Abstract

PURPOSE:To obtain the inexpensive title resin suitable for coating of automobile, electrical product, etc., and being excellent in water resistance and flexibility of coating film, by using a specific alkyl-etherified amino resin as an amino resin. CONSTITUTION:The aimed composition containing (A) 5-60wt.% (as solid content) alkyletherified amino resin obtained by addition and condensation of an amino compound (being 1 in sum of molar ratio of melamine and molar ratio of spiroguanamine) with formaldehyde and etherification reaction of the resultant product with <=3C alcohol and being z>3x+4y in average binding formaldehyde number z to melamine nucleus number x and spiroguanamine nucleus number y and (B) 95-40wt.% water soluble or water dispersing resin.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a resin composition for water-based paints.

(Prior Art) In recent years, there has been a strong demand for labor-saving and energy-saving coatings for automobiles, industrial machinery, real furniture, electrical appliances, etc. Furthermore, in recent years, it has been used to prevent air pollution caused by organic solvents emitted from paints.

The transition from traditional solvent-based paints to water-based paints is progressing.

In water-based paints containing amino resin as a curing agent,
As the amino resin, methyl etherified melamine resin is mainly used because of its water solubility. However, a typical water-based paint using hexamethoxymethylolmelamine can provide a coating film with good flexibility, but has a problem of poor water resistance.

Furthermore, amino resins with a low degree of addition have problems in resin stability, and amino resins containing a large amount of residual methylol groups have problems in paint stability and coating film flexibility. Also,
Alkyl etherified spiroguanamine resins have the drawback of being very expensive.

(Problems to be Solved by the Invention) The present invention solves these problems, and uses a specific alkyl etherified amino resin (
The purpose of the present invention is to provide an inexpensive resin composition for water-based paints that uses an alkyl etherified spiroguanamine/melamine cocondensation resin and has excellent water resistance and removability of the paint film.

(Failure to solve the problem) In other words, the present invention is as follows.

(2) An amino compound composed of melamine and spiroguanamine (here, the molar ratio of melamine is X and the molar ratio of spiroguanamine is y (X+y=1)) is added with formaldehyde.

An alkyl etherified amino resin obtained by condensation and etherification reaction with an alcohol having 3 or less carbon atoms, wherein the average number of formaldehyde bonds 2 to X melamine nuclei and y spiroguanamine nuclei is 2Z>3X+4Y
5 to 60 parts by weight (solid content) of an alkyl etherified amino resin satisfying the following conditions and (B) 95 to 40 m' of a water-soluble or water-dispersible resin! The present invention relates to a water-based paint composition containing Li (solid content) in an amount of 100 parts by weight.

The method for producing the alkyl etherified amino resin, component (5) of the present invention, is already known and can be easily synthesized by appropriately selecting reaction conditions.

For example, -1', an aldehyde such as formaldehyde, paraformaldehyde, etc., is converted into an amino compound composed of melamine and spiroguanamine (here, the molar ratio of melamine is X, the molar ratio of spiroguanamine is y (X + y
=1). ), and the average formaldehyde number 2 bound to X melamine nuclei and y spiroguanamine nuclei satisfies the formula 1: z>3 x+4 y.

When 2 does not satisfy this formula, the alkyl etherified amino resin tends to become cloudy, and when used as a paint, the stability of the paint is poor (for example, two-layer separation).

The performance of the coating film (flexibility in %) is also poor. Ensuring that 2 satisfies the above formula can be achieved mainly by selecting the reaction conditions when adding the aldehyde to the amino compound.

The reaction conditions are 2-10F5 at a temperature of 50-80℃.
? It is preferable to carry out an addition reaction between P.

Further, the (melamine and spiroguanamine)/aldehyde (molar ratio) is preferably in the range of 1/30 to 1/4, more preferably in the range of 1/20 to 1/10.

The alkyl etherified amino resin of the present invention is obtained by further alkyl etherifying the above adduct with an alcohol having 3 or less carbon atoms (methanol, ethanol, propatool or isopropanol), and further by a condensation reaction, The molecular weight is adjusted to suit the purpose. When an alcohol having 4 or more carbon atoms is used, the water solubility or water dispersibility is poor. The amount of alcohol used is (melamine and spiroguanamine)/alcohol (molar ratio) 1/30 to 1.
A range of 15 is preferable.

The alkyl etherified amino resin of the present invention can be produced by various methods.

For example, spiroguanamine, melamine, formaldehyde and methanol are mixed and heated under alkaline conditions (preferably pH 9 to 11) to cause an addition reaction, and then heated under acidic conditions (preferably pH 2 to 5) to undergo condensation. and an alkyl etherification reaction method, in which spiroguanamine, melamine, formaldehyde, and methanol or water are mixed and heated under alkalinity, and the resulting spiroguanamine and melamine adduct is isolated once, and methanol is added to it. In addition, there is a method of carrying out a heating reaction under acidic conditions.

In addition, spiroguanamine is 2,4,8.10-tetraoxaspiro[5,5]undecane-49-bis(2-
ethylguanamine) and its structure is shown by the formula below. This product can be obtained, for example, under the trade name CTU Guanamine manufactured by Ajinomoto ■.

The water-soluble or water-dispersible component (B) of the present invention.

(1) There are no particular restrictions on the material as long as it reacts with the alkyl etherified amino resin of component (2) Examples include water-soluble or water-dispersible alkyd resins, water-soluble or water-dispersible acrylic resins, and the like.

The above-mentioned water-soluble or water-dispersible alkyd resin is, for example, a neutralized product of an alkyd resin obtained by reacting a polycarboxylic acid, a polyhydric alcohol, and, if necessary, an oil or a fatty acid thereof. Examples of polyhydric carboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, and pleic acid.

Fumaric acid, cono-phosphoric acid, adipic acid, hetano(cinic acid).

These include trimellitic acid and pyromellitic acid. These may be used in the form of ester-forming derivatives such as acid anhydrides and methyl esters. Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, flopylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, trimethylene glycol, glycerin, and trimethylolpropane. , trimethylolethane, and pentaerythritol.

Examples of the oil include tung oil, linseed oil, soybean oil, dehydrated mustard oil, safflower oil, castor oil, coconut oil, and tall oil. The alkyd resin can be produced by a known method,
When oil is used, oil and polyhydric alcohol are reacted at 200 to 260°C in the presence of a transesterification catalyst such as lithium hydroxide.

Add polybasic acid and remaining polyhydric alcohol to 180-25
There are a method of reacting at 0°C, and a method of mixing raw materials and reacting at 180 to 250°C when no oil is used.

Moreover, the above-mentioned water-soluble or water-dispersible acrylic resin.

α, β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-methacrylic acid - Neutralized acrylic resins obtained by copolymerizing α,β-ethylenically unsaturated monomers having hydroxyl groups such as hydroxypropyl and other unsaturated monomers. Examples of other unsaturated monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and n-butyl methacrylate.

Alkyl esters of β-monoethylenically unsaturated carboxylic acids, acrylamide, methacrylamide.

Acrylamide derivatives such as N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, glycidyl esters of α,β-monoethylenically unsaturated carboxylic acids such as glycidyl acrylate and glycidyl methacrylate, vinyl acetate, vinyl propionate, etc. vinyl esters of saturated carboxylic acids, aromatic unsaturated monomers such as styrene, α-methylstyrene, and vinyltoluene. The above copolymerization is azobisisobutyronitrile and benzoyl peroxide.

This can be carried out by heating to 130 to 160°C in the presence of a radical catalyst such as dibutyl peroxide or cumene hydroperoxide.

Alkyd resin and acrylic resin before neutralization.

It is preferable to adjust the acid value to 20 to 300 and the hydroxyl value to 15 to 400. It is more preferable to adjust the acid value to 20 to 100 and the hydroxyl value to 15 to 200. If the acid value is too low, the water solubility or water dispersibility will be poor after neutralization, and if the acid value is too high, the coating film properties will tend to deteriorate. Also.

If the hydroxyl value is too small, the curability will be poor, and if it is too large, the water resistance of the coating film will be poor.

In order to make such alkyd resins and acrylic resins water-soluble or water-dispersible before neutralization, the acid groups of the resins may be neutralized with a volatile base such as ammonia or amino. teeth.

For example, monopropylamino, monobutylamino.

diethylamino, digtylamino, triethylamino,
Tributylamino, monoethanolamino.

Secondary and tertiary aliphatic or cycloaliphatic amino acids can be used, such as ethyl monoethanolamino, monocyclohexylamino, morpholine, and piperidine. The amount of ammonia and amino is 0.3 to 1.0% per equivalent of acid group.
Preferably, 2 moles are used.

In the present invention, the alkyl etherified amino resin (Al component) and the water-soluble or water-dispersible resin (Bl component) are
(3)/(B) is 5/95 to 60 in weight ratio (solid content ratio)
/40. If it exceeds this range, the coating properties such as curability or flexibility of the coating film will be poor.

Further, a catalyst such as an inorganic acid such as hydrochloric acid or phosphoric acid, or an organic acid such as para-toluenesulfonic acid may be added to the resin composition for water-based paint of the present invention.

The amount used is based on 100 parts by weight (solid content) of component (■).

It is preferably 1 part by weight or less.

The resin composition for water-based paints of the present invention comprises butyl cellosolve,
Ethyl cellosolve, methyl cellosolve.

It can be used in a suitable solid content by using a mixed solvent of water and a water-soluble solvent such as diacetone alcohol, 3-methoxy-3-methylbutan-1-ol, isopropanol, ethanol, and methanol. The water-soluble organic solvent is preferably used in an amount of 5 parts by weight or more per 100 parts by weight of water, especially 1
It is preferable to use 0 parts by weight or more.

The resin composition for water-based paints of the present invention may contain pigments,
Other additives may also be used.

In addition, coating methods include spray painting, roll coater
Painting, dipping, etc. can be used.

Next, nine production examples and examples related to the present invention will be shown. Hereinafter, 9 parts and 1 indicate parts by weight and % by weight, respectively.

(Example) [Production Example 1] In a flask equipped with a stirrer, a reflux condenser, and a thermometer,
80 Ciparaformaldehyde (contains 20% water) 75
Weigh out 0.09 (20 moles), 800 g (25 moles) of methanol, and 30% sodium hydroxide Z6, and further add 390.89 (0.9 moles) of spiroguanamine and 12 melamine.
．． 69 (0.1 mol) was added, the temperature was raised to 60°C, and an addition reaction was carried out at the same temperature for 4 hours. Then, add 62% nitric acid to 3.0
g was added, the pH was adjusted to '3.5, and the alkyl etherification reaction was carried out at 70°C for 10 hours. After the reaction is completed, 3
The reaction solution was made alkaline pI (10
, 0, and concentrated under reduced pressure. The amount produced at this time is 630
It was 9. Dilute this resin with butyl cellosolve,
The non-volatile content was adjusted to 75%. The viscosity was Y-Z (Gardna/25°C).

[Production Example 2] Using the same apparatus as Production Example 1, 80% paraformaldehyde 750.09 (20 mol), methanol 8009 (
25 mol), 30 sodium hydroxide 2.69 was weighed out, and further spiroguanamine 304.09 (0.7 mol)
, 37.89 (0.3 mol) of melamine was added, the temperature was raised to 60°C, and an addition reaction was carried out at the same temperature for 4 hours. then 62
3.% nitric acid. After the reaction was completed, the reaction solution was made alkaline (pH
10.0) and concentrated under reduced pressure. The amount produced at this time was 5509. This resin was diluted with butyl cellosolve to adjust the solid content to 75%. The viscosity was X (Gardna/25°C).

[Production Example 3] Using the same apparatus as Production Example 1, 80% paraformaldehyde 750.09 (20 mol), methanol 8009 (
25 mol), 30 sodium hydroxide 2.69 was weighed out, and spiroguanamine 217.19 (0.5 mol) was added.
, 63.09 (0.5 mol) of melamine was added, the temperature was raised to 60°C, and an addition reaction was carried out at the same temperature for 4 hours. then 62
Add 3.0g of % nitric acid, adjust the pH to 3.5, and heat at 60°C.
The alkyl etherification reaction was carried out for 10 hours. After completion of the reaction, one reaction solution was converted to an alkaline earth metal (io, o) with IJ hydroxide and concentrated under reduced pressure. The amount produced at this time was 5009. This resin was diluted with butyl cellosolve to adjust the solid content to 75%.

The viscosity was W (Gardner 725°C).

[Comparative Production Example 1] Using the same apparatus as in Production Example 1, 80% paraformaldehyde 3009 (8 mol), methanol 800 g (25 mol), and 30% sodium thihydroxide Z69 were weighed out, and spiroguanamine 304. After adding 0.09 (0.7 mol) and melamine 37.89 (0.3 mol) and raising the temperature to 60°C, an addition reaction was carried out at the same temperature for 1 hour.

Thereafter, 3.0 g of 62% nitric acid was added, the pH was adjusted to 3.5, and an alkyl ether reaction was carried out at 60° C. for 2 hours. After the reaction was completed, the reaction solution was made alkaline (pH 10.0) with 30% sodium hydroxide and concentrated under reduced pressure. The amount produced at this time was 4 sog. Dilute this resin with butyl cellosolve.

The solid content was adjusted to 75 tons. Viscosity ViM (Gardona/2
5°C).

X melamine nuclei and y spiroguanamine nuclei of the alkyl etherified amino resin (alkyl etherified spiroguanamine/melamine cocondensation resin) obtained as above
Table 1 shows the analysis results of the average number of bound formaldehyde (2) and the average number of bound methanol for each sample.

Table 1 ×1) Based on phosphoric acid decomposition method and NMR analysis.

*2) Based on NMR analysis.

Further, Table 2 shows the relationship between the molar ratio X of melamine, the molar ratio y of spiroguanamine, and the average number of bound formaldehydes 2 to X melamine nuclei and y spiroguanamine nuclei in the alkyl etherified amino resin.

Table 2 [Examples 1 to 2 and Comparative Example 1] Alkyl etherified amino resin and water-soluble acrylic resin of production example (Hitachi Chemical Co., Ltd. trade name Hytaloid 7)
200, solid content: 50%, solvent: water/isopropanol) and titanium white in the formulation shown in Table 3, and after roll kneading, thinner (composition, butyl cellosolve/water = 1)
0/90) for 20 seconds (25
After adjusting the viscosity so that the film thickness is 30 to 40μ/D
Spray paint on the coating plate (Bonply Donna 144) so that it is 160 degrees Celsius after leaving it at room temperature for about 20 minutes.
I baked it for 20 minutes. Table 3 shows the performance of the resulting coating film.

Table 3 Formulation (unit: 2 parts) ×1) Hitachi Chemical Co., Ltd. Product name Melan 523 *2)
Hitachi Chemical Co., Ltd. Trade name Melan 620 Table 4 The test method for coating film performance is as follows.

The following (1) to (5) were performed according to JIS K 5400.

(1) Gloss = Measured at 60 degrees specular skin emissivity.

(2) Pencil hardness: Judged with Mitsubishi Pencil Uni.

(3) Cross cut: Cut the coating surface with a cutter knife.
100 squares were cut at - intervals, and the number of squares remaining when peeled off with cello tape was judged.

(4) Erichsen value: Measured with an Erichsen tester.

(5) Impact value: Determined in centameter using a Devon impactor "/'-500g."

(6) Boiling water resistance: After being immersed in boiling water for 1 hour, it was taken out and the condition of the coating surface was visually judged.

○ No change △ Slightly immersed X Vigorously immersed (effects of the invention) The resin composition for water-based paints according to the present invention has excellent water resistance and removability of the coating film, and is inexpensive.

Claims (1)

[Scope of Claims] (A) An amino compound composed of melamine and spiroguanamine (here, the molar ratio of melamine is x and the molar ratio of spiroguanamine is y (however, x+y=1))
is an alkyl etherified amino resin obtained by addition, condensation, and etherification reaction with formaldehyde and an alcohol having 3 or less carbon atoms, in which the average number z of formaldehyde bound to x melamine nuclei and y spiroguanamine nuclei is expressed by the formula z 5 to 60 parts by weight (solid content) of an alkyl etherified amino resin satisfying >3x+4y and 95 to 40 parts by weight (solid content) of a water-soluble or water-dispersible resin (B) in an amount that makes the total amount 100 parts by weight. A water-based paint composition comprising: