JPH04342717A - Water-dispersible type resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, composed of a specific acrylic- modified epoxy resin and a spiroguanamine resin, etc., in a prescribed proportion, capable of baking at high temperatures in a short time and providing films excellent in water resistance, adhesion and flexibility and useful as coatings, adhesives, etc. CONSTITUTION:The objective composition containing (A) 99-65 pts.wt. (solid content) acrylic-modified epoxy resin prepared by reacting (i) an acrylic resin prepared by partially neutralizing a carboxyl functional polymer having 5000-12000 number-average molecular weight and 100-350 acid value with NH3 or an amine with (ii) an aromatic epoxy resin having 1.25-1.5 average epoxy groups, 2.7-3.2 dispersity and 4500-8000 number-average molecular weight at (95/5)-(60/40) weight ratio of epoxy resin/acrylic resin and (B) 1-35 pts.wt. spiroguanamine or acetoguanamine resin obtained by adding an aldehyde which is a reaction curing agent and alkyl etherifying the resultant product with a 1-4C alcohol. The components (A) and (B) are contained in amounts so as to provide 100 pts.wt. total amount thereof.

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 useful for paints, adhesives, and the like.

0002

BACKGROUND OF THE INVENTION In recent years, there has been a strong demand for labor-saving and energy-saving paints and adhesives for coating automobile industrial machinery, steel furniture, electrical appliances, and the like. Furthermore, in order to prevent air pollution caused by organic solvents emitted from paints, a shift from conventional solvent-based paints to water-based paints is progressing. However, a water-based paint that can be baked for a short time and provides a well-balanced cured coating film with water resistance, adhesion, and flexibility has not yet been found.

0003

[Problems to be Solved by the Invention] The present invention solves these problems by providing a water-dispersed heat treatment that enables short-time baking and provides cured coatings with excellent water resistance, adhesion, and flexibility. A curable resin composition is provided.

0004

[Means for Solving the Problems] That is, the present invention provides (A
) Number average molecular weight 5,000 to 12,000 and acid value 1
00 to 350, partially neutralized with ammonia or amine, and an acrylic resin (a) having an average of 1.25 or more and less than 1.5 epoxy groups in one molecule. , an aromatic epoxy resin (b) having a dispersity of 2.7 to 3.2 and a number average molecular weight of 4,500 to 8,000 is mixed into an epoxy resin (b)/acrylic resin (a) (by weight 99 to 65 parts by weight (solid content) of an acrylic modified epoxy resin (solid content) reacted with a ratio of 95/5 to 60/40 and (B) an aldehyde as a reaction curing agent, and alkyl with an alcohol having 1 to 4 carbon atoms. Etherified spiroguanamine, acetoguanamine resin 1-3
5 parts by weight (solid content) and the total amount ((A) + (B)) is 10
It relates to a water-dispersed resin composition containing the present invention in an amount of 0 parts by weight.

The present invention will be explained in detail below. The carboxyl-functional polymers of the present invention include α,β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid, etc. It is an acrylic resin obtained by copolymerizing α,β-ethylenically unsaturated monomers having hydroxyl groups such as 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, and other unsaturated monomers. Other unsaturated monomers include α, β-monoethylenically unsaturated monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and n-butyl methacrylate. Alkyl esters of carboxylic acids, acrylamide derivatives such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, glycidyl acrylate, glycidyl methacrylate, etc.
Examples include glycidyl esters of β-monoethylenically unsaturated carboxylic acids, vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate, and aromatic unsaturated monomers such as styrene, α-methylstyrene, and vinyltoluene. The above copolymerization includes azobisisobutyronitrile, t-
130 to 160 in the presence of a radical catalyst such as butyl peroxybenzoate, benzoyl peroxide, dibutyl peroxide, cumene hydroperoxide, etc.
This can be done by heating to ℃.

[0006] The carboxyl functional polymer (acrylic resin before neutralization) is adjusted to have an acid value of 100 to 350;
It is preferable to adjust it to 320. If the acid value is less than 100, the water solubility or water dispersibility of the acrylic modified epoxy resin (A) obtained after the reaction with the epoxy resin (b) will be poor, and the stability of the coating material will be poor. Moreover, if the acid value is too large than 350, the coating film properties (especially hot water resistance) will deteriorate. Moreover, it tends to gel when reacting with the epoxy resin (b).

The number average molecular weight of the carboxyl functional polymer is 5,000 to 12,000, and 7,000 to 12,000.
11,000 is more preferred. Number average molecular weight is 5,00
If it is less than 0, the hot water resistance and processability will be poor, and if it exceeds 12,000, the viscosity of the final product will be high, which is not preferable.

In order to make such carboxyl-functional polymers water-soluble or water-dispersible, the acid groups of the resin can be neutralized with a volatile base such as ammonia or an amine, with suitable amines including: For example, monopropylamine,
Monobutylamine, diethylamine, dibutylamine,
Triethylamine, tributylamine, monoethanolamine, ethylmonoethanolamine, monocyclohexylamine, dimethylaminoethanol, 2-amino-
Primary, secondary and tertiary aliphatic or cycloaliphatic amines can be used, such as 2-methyl-1-propanol, morpholine, piperidine. Ammonia and amine are preferably used in an amount of 0.6 to 1.0 mol per mol of acid group. If the amount of amine is less than 0.6 mole, water dispersibility or water solubility tends to be poor, and if it exceeds 1.0 mole, the viscosity of the final product tends to be high, which is not preferable. In this way, the number average molecular weight of the acrylic resin (a) obtained by neutralizing the carboxyl functional polymer is 5,000 to 1.
It is preferably 2,000, and the acid value is 100 to 35.
Preferably, it is 0.

In the present invention, the dispersity (weight average molecular weight/number average molecular weight) having an average of 1.25 or more and less than 1.5 epoxy groups in one molecule is 2.7 to 3.2, and the number average An aromatic epoxy resin (b) having a molecular weight in the range of 4,500 to 8,000 is used. When the number of epoxy groups in one molecule is less than 1.25, water dispersibility decreases. If the number is 1.5 or more, processability and adhesion will decrease.

[0010] If the molecular weight dispersity is less than 2.7, the flexibility of the cured coating will decrease, while if it exceeds 3.2, the processability and adhesion of the cured coating will decrease, and the coating will deteriorate. The viscosity increases and the stability of the paint decreases. From the viewpoint of these characteristics, 2.8 to 3.1 is preferable. Furthermore, if the number average molecular weight is less than 4,500, the processability and adhesion of the cured coating will decrease, while if it exceeds 8,000, gelation will occur easily during the reaction with the acrylic resin (A), and the coating will Viscosity increases and paint stability decreases. From the viewpoint of these characteristics, the number is preferably 5,500 to 7,500, particularly preferably 6,000 to 7,000. Although there are no limitations on the method for producing such aromatic epoxy resin (b), for example,
It can be easily produced by using DER343 (diglycidyl ether of bisphenol A, trade name) and bisphenol A sold by Dow Chemical Company. In addition, the present inventors conducted a similar study using Epon 829 (glycidyl ether of bisphenol A, trade name) manufactured by Shell Chemical, but the aromatic epoxy resin (b) was easily removed due to the large amount of low molecular weight substances. Could not be manufactured. This is thought to be due to the type of catalyst for molecular chain elongation, and the complex of ethyltriphenylphosphonium acetate and acetic acid contained in DER343 is considered to be effective in producing aromatic epoxy resin (b). . The aromatic epoxy resin (b) can be synthesized using, for example, bisphenol A and the trade name DER343 (diglycidyl ether of bisphenol) sold by The Dow Chemical Company. In this case, bisphenol A/DER34
The weight ratio of 3 to 3 is preferably 33.4 to 32/66.6 to 68 from the viewpoint of molecular weight control. Bisphenol A
For the reaction between and DER343, the reaction temperature was set at 180-190
It is preferable to carry out the reaction at ℃. If the reaction temperature is less than 180°C, it will take a long time to obtain the final target molecular weight, and
The content of low molecular weight substances increases and the curability of the final product decreases. On the other hand, if the temperature exceeds 190°C, it becomes difficult to control the reaction. Also, it is better not to use a reaction solvent. When a reaction solvent is used, the reaction time becomes longer and the content of low molecular weight substances increases.

In the present invention, the reaction between the partially neutralized acrylic resin (a) and the aromatic epoxy resin (b) is carried out at 80%
The partially neutralized acrylic resin (a) is added to the aromatic epoxy resin (b) kept at ~100°C, and then heated to 65~8°C.
This can be done by incubating at 5°C for 10 to 45 minutes. . The reaction was controlled using the acid value oxirane (%
) can be measured. The weight ratio of this partially neutralized acrylic resin/aromatic epoxy resin (b)/partially neutralized acrylic resin (a) is 95/5 to 60/40.
(carboxyl group/epoxy group (molar ratio) is approximately 5 to 20) is preferable. (a) When the amount of component used increases, the processability and corrosion resistance of the coating film decreases, and (b)
As the amount of components increases, the dispersibility and stability of the paint decrease. Acrylic modified epoxy resin obtained in this way (
The number average molecular weight of A) is preferably 10,000 to 25,000. The acid value is preferably 20-80.

Furthermore, the alkyl etherified spiroguanamine and acetoguanamine resins of the present invention are already known resins, and can be easily synthesized by appropriately selecting reaction conditions. First, formaldehyde or paraformaldehyde is added to spiroguanamine or acetoguanamine, and then alkyl etherification is performed with an alcohol having 4 or less carbon atoms. For example, first methanol, paraformaldehyde, spiroguanamine (and/or acetoguanamine)
are mixed, heated under alkaline conditions (preferably pH 9 to 11) to cause an addition reaction, and then resistant (preferably pH 9 to 11).
There is a method of heating under H2-6) to cause condensation and etherification reactions. In addition, in a method different from the above, methylolspiguanamine (and/or acetoguanamine), formaldehyde, methanol, and water are mixed, heated under alkalinity, and subjected to an addition reaction. This method involves isolating n-butanol, adding n-butanol to it, and conducting a heating reaction under acidic conditions to carry out etherification and condensation reactions. In such a production method, 4 to 20 mol of formaldehyde per 1 mol of spiroguanamine (and or acetoguanamine),
It is desirable to use methanol in a proportion of 5 to 30 moles.

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 water-based coating composition of the present invention. The amount used is (A) + (
It is preferably 1 part by weight or less per 100 parts by weight of component B) (solid content).

The water-based coating composition of the present invention contains butyl cellosolve, ethyl cellosolve, methyl cellosolve, diacetone alcohol, 3-methoxy-3-methylbutane-1
It is preferable to use a mixed solvent of a water-soluble organic solvent such as -ol, isopropanol, ethanol, methanol, etc. and water as a diluent to obtain an appropriate solid content. water/
It is preferable that the organic solvent (weight ratio) is 95/5 to 80/20. This diluent has a viscosity of 150 to 2,000 cp when the solid content of the water-dispersed resin composition is 30% by weight.
It is preferable to use the amount such that s.

The resin composition for water-based paints of the present invention may contain pigments and other additives depending on the purpose. Further, as a coating method, spray coating, coating with a roll coater, dipping, etc. can be adopted.

[0016]

[Examples] The present invention will be specifically explained below using Examples.

A partially neutralized acrylic resin was produced by the following method. [Production Example 1] In a flask equipped with a stirrer, reflux condenser, thermometer, and inert inlet, 35 parts by weight of butyl cellosolve,
Add 20 parts by weight of butanol and heat. The temperature was raised to 130°C, and a mixed solution consisting of 28 parts by weight of styrene, 26 parts by weight of ethyl acrylate, 46 parts by weight of methacrylic acid, and 0.6 parts by weight of t-butyl peroxybenzoate was dropped into the flask over 3 hours. I let it happen. Thereafter, 5 parts by weight of butyl cellosolve and 23 parts by weight of butanol were added dropwise over 20 minutes, followed by keeping warm for 2 hours to obtain a carboxyl functional polymer. (Acid value 300) (solid content conversion) After that 1
The mixture was cooled to 00°C, 47 parts by weight of water was added, and further 31 parts by weight of dimethylaminoethanol was added at 80°C to obtain a partially neutralized acrylic resin (neutralization rate 65%). Thereafter, water was added to adjust the heating residue to 37% by weight. The acid value at this time was 300 (in terms of solid content). In addition, the number average molecular weight is 9,700, the weight average molecular weight is 24,
It was 200. [Production Example 2] Into a flask equipped with a stirrer, reflux condenser, thermometer, and inert inlet, 35 parts by weight of butyl cellosolve,
Add 20 parts by weight of butanol and heat. The temperature was raised to 130°C, and a mixed solution consisting of 32 parts by weight of styrene, 30 parts by weight of ethyl acrylate, 38 parts by weight of methacrylic acid, and 0.6 parts by weight of t-butyl peroxybenzoate was dropped into the flask over 3 hours. I let it happen. Thereafter, 5 parts by weight of butyl cellosolve and 23 parts by weight of butanol were added dropwise over 20 minutes, followed by keeping warm for 2 hours to obtain a carboxyl functional polymer. (Acid value 250) (solid content conversion) After that 1
The mixture was cooled to 00°C, 47 parts by weight of water was added, and further 23.6 parts by weight of dimethylaminoethanol was added at 80°C to obtain a partially neutralized acrylic resin (neutralization rate 65%). after that,
Water was added to adjust the heating residue to 37% by weight. The acid value at this time was 250 (calculated as solid content). In addition, the number average molecular weight is 9,600, and the weight average molecular weight is 2.
It was 1,300.

Synthesis of aromatic epoxy resin [Production Example 3] Weigh out 405 parts by weight of glycidyl ether type epoxy resin of bisphenol A (trade name: DER343 (manufactured by Dow Chemical) and 220 g of bisphenol, and add a stirrer, a reflux condenser, and a thermometer. , into a flask equipped with an inert gas inlet. Adjust the heating so that the temperature reaches 130°C in about 30 minutes, then stop heating and use the heat of reaction to raise the temperature to 190°C.
The temperature rose to The mixture was reacted at this temperature for 2 hours to synthesize an aromatic epoxy resin. The number average molecular weight (Mn) at this time is 6
, 550, weight average molecular weight (Mw) of 19,600, and degree of dispersion (Mw/Mn) of 2.99.

Synthesis of alkyl etherified spiroguanamine and acetoguanamine resin (amino resin) [Production Example 4] Using the same apparatus as in Production Example 1, 80% by weight paraformaldehyde (containing 20% by weight water) 562. 5g
(15 mol), methanol 640g (20 mol), 30
2.6 g of wt% sodium hydroxide was weighed out, 434.2 g (1 mol) of spiroguanamine was further added, and an addition reaction was carried out at reflux temperature (83° C.) and pH 10.5 for 4 hours. Thereafter, 2.0 g of 62% by weight nitric acid 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 was completed, the reaction solution was again made alkaline (pH 10.0) with 30% by weight sodium hydroxide and concentrated under reduced pressure. The amount produced at this time was about 650 g. This resin was diluted with butyl cellosolve to adjust the solid content to 75% by weight. The viscosity was Y (Gardna/25°C).

[Production Example 5] Using the same synthesis apparatus as in Production Example 1, 225 g (6 moles) of 80% by weight paraformaldehyde (containing 20% water) and 320 g (6 moles) of methanol were added.
10 mol) and 0.2 g of 30% by weight sodium hydroxide were weighed out, 125 g (1 mol) of acetoguanamine was added, and the temperature was raised to 60°C (pH 10.3) to carry out an addition reaction for 4 hours. Then, 0.15 g of 62% by weight nitric acid was added, and p
H was adjusted to 3.5. After performing the alkyl etherification reaction at 60° C. for 6 hours, the reaction solution was again made alkaline (pH 10.0) with 30% by weight sodium hydroxide and concentrated under reduced pressure. The amount produced at this time was 285 g. This resin was diluted with butyl cellosolve and the solid content was 75% by weight.
Adjusted to. The viscosity was W (Gardna/25°C).

[Comparative Production Example 1] Using the same apparatus as in Production Example 1, 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 a mixed solution consisting of 57 parts by weight of styrene, 32 parts by weight of ethyl acrylate, 11 parts by weight of methacrylic acid, and 0.6 parts by weight of t-butyl peroxybenzoate was dropped into the flask over 3 hours. I let it happen. Then 5 parts by weight of butyl cellosolve,
23 parts by weight of butanol was added dropwise over 20 minutes, and the mixture was kept warm for 2 hours to obtain an acrylic resin. Thereafter, the mixture was cooled to 100°C, 47 parts by weight of water was added, and further 7.4 parts by weight of dimethylaminoethanol was added at 80°C to obtain a partially neutralized acrylic resin (neutralization rate 65%). Thereafter, water was added to adjust the heating residue to 37%. The acid value at this time was 75 (calculated as solid content).

[Comparative Manufacturing Example 2] Using the same equipment as in Manufacturing Example 3, 405 parts by weight of epoxy resin DER343 (manufactured by Dow Chemical) and 180 parts by weight of bisphenol were weighed out and heated to 130°C in about 30 minutes. Adjust the heating to 130°C, then stop heating at 130°C, and use the reaction heat to
The temperature was raised to 90°C. The reaction was carried out at this temperature for 2 hours to obtain a polymeric epoxy resin. Number average molecular weight (Mn) at this time
is 4,250, weight average molecular weight is 9,850, dispersity (
Mw/Mn) was 2.32.

[Example 1] The epoxy resin obtained in Production Example 3 was cooled to 130°C, 50 parts by weight of butanol was added,
After thorough stirring, when the temperature reached 100°C, 435 parts by weight of the partially neutralized acrylic resin synthesized in Production Example 1 was added (epoxy resin/acrylic resin = 80/20; solid content weight ratio). Thereafter, the mixture was stirred at 80° C. for 30 minutes to obtain an acrylic modified epoxy resin. The acid value at this time was 34. Thereafter, 1100 parts by weight of water was added over 1 hour to obtain a white water-dispersed resin. This resin was further adjusted with water so that the solid content was 30% by weight. The viscosity at this time is 450 cps
(B type viscosity 6 r·p·m). To 200 parts by weight of this resin, 14.1 parts by weight of the amino resin synthesized in Production Example 4 (
Solid content ratio: 85/15) was added.

[Examples 2 to 4 and Comparative Examples 1 to 4] Synthesis was carried out in the same manner as in Example 1 according to the formulations in Table 1 below, and the water-dispersed resins were obtained.

[0025]

[Table 1]

Characteristic values of the synthetic products and coating film tests of the water-dispersed resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 5 were measured under the following conditions. Each resin composition adjusted to 30% was applied to a tin plate using a bar coater #18 (the film thickness was 5 to 7 μm after baking). This coating plate is 190,
Baking was performed at 200°C and 210°C for 2 minutes each. Then, it was left at room temperature for 24 hours and a coating test was conducted. Stability: The paint was left at room temperature (25°C) for 60 days, and the viscosity change and appearance of the paint were measured. Paint film test method/Pencil hardness JIS K5400 using Mitsubishi Uni
Evaluated by.・Impact value: Determined using a DuPont impactor 1/2"-500. ・Boiling water resistance: Immersed in boiling water for 1 hour, then taken out.
Its appearance was judged.・Boiling water resistant adhesion After immersing in boiling water for 1 hour, 1mm on the paint film
100 squares of ×1 mm were cut, and the rate of peeling was determined by peeling off cellophane tape. - Erichsen after boiling water resistance After 1 hour of boiling water, extrude 5mm using Erichsen test and observe the appearance of the coating film. The evaluation results are shown in Tables 2, 3 and 4.

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

The water-dispersed resin composition obtained by the present invention can be baked at high temperatures for a short time, and the resulting coating film has excellent water resistance, adhesion, and flexibility.

[0031]

[Effects of the Invention] The water-dispersed resin composition of the present invention has excellent stability and can be baked for a short time, and the resulting cured coating film has excellent water resistance, adhesion, flexibility, etc. be.

Claims (2)

[Claims] Claim 1: (A) Number average molecular weight 5,000-12
,000 and an acid value of 100 to 350, partially neutralized with ammonia or amine, and an acrylic resin (a) having an average of 1.
It has 25 or more but less than 1.5 epoxy groups, a degree of dispersion of 2.7 to 3.2, and a number average molecular weight of 4,500 to 8,0.
Aromatic epoxy resin (b) in the range of 0.00 and epoxy resin (b)/acrylic resin (a) (weight ratio) of 95.
99 to 65 parts by weight (solid content) of the acrylic modified epoxy resin reacted as /5 to 60/40 and (B) aldehyde as a reaction curing agent were added, and the mixture was converted into alkyl ether with an alcohol having 1 to 4 carbon atoms. Spiguanamine, acetoguanamine resin 1 to 35 parts by weight (solid content) and the total amount ((
A water-dispersed resin composition containing A)+(B)) in an amount of 100 parts by weight. Claim 2: Water/organic solvent (weight ratio) from 95/5 to
The water-dispersed resin composition according to claim 1, which has a viscosity of 150 to 2,000 cps when the solid content is 30% by weight when diluted with an 80/20 diluent.