JPS6259619A - Production of phenolic resin for adding to epoxy resin paint - Google Patents

Abstract

PURPOSE:To obtain the titled resin which is excellent in adhesion to an adherend and can give a paint film of a light color, by reacting a phenol with a formaldehyde in a wealky acidic condition by using an organic acid metal salt as a catalyst. CONSTITUTION:1.0mol (in terms of phenol nuclei) of a phenol (e.g., o-cresol) is reacted with 1.0-3.0mol of a formaldehyde (e.g., paraformaldehyde) for 1-10hr at 80-140 deg.C and a pH at 25 deg.C of 3.5-6.8, preferably, 4.5-6.0 by using 0.0005-0.0100mol of at least one organic acid metal salt selected from among bivalent metal salts of carboxylic acids and naphthenic acids (e.g., lead naphthenate) to obtain the titled resin in which the rate of the number of moles of dimethylene ether bonds to the sum of the number of moles of dimethylene ether bonds, that of methylene bonds and that of methylol groups is 20% or above, preferably, 30% or above.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an epoxy resin paint (2) which can be blended and baked to provide excellent adhesion to the object to be coated (2), and A method for producing a heat-reactive phenolic resin for blending in epoxy resin paints, in which the resulting coating film is light-colored.

[Prior art]

Traditionally, epoxy resin paints containing heat-reactive phenolic resins have been widely used because the paint film after baking has excellent properties such as heat resistance, corrosion resistance, chemical resistance, and content resistance. has been done. General (=, bisphenol A type epoxy resin obtained by reacting bisphenol A and epichlorohydrin in the presence of caustic soda (
The heat-reactive phenolic resin used in the second paint is 1
reacting a species or two or more phenols with formaldehyde under basic conditions using an alkali catalyst;
Or two or more different types of phenolic resins with different properties] □Enols are reacted with formaldehyde separately and then used as a mixture.These phenolic resins are No. 59-42705, etc. (No. 2 is publicly known. In this case, hydroxides and carbonates of alkali metals such as sodium and potassium, calcium, barium, and magnesium are used as the melting medium for the reaction. One or more selected from hydroxides and oxides of alkaline earth metals such as ammonia and amines such as triethylamine and triethanolamine.However, these phenols and formaldehyde Epoxy resin paints containing heat-reactive phenolic resin obtained by reacting phenolic resins under basic conditions do not adhere well to the surface of the coated object during baking, and are strongly yellowed. For baking, it is required to improve the adhesion of the coating film to the object to be coated and to lighten the color.

[Purpose of the invention]

The method for producing a phenolic resin for compounding epoxy resin paints of the present invention improves the adhesion of the paint film to the object being coated and lightens the color ( As a result of intensive research on the two, we found that a thermally reactive phenolic resin obtained by reacting phenols and formaldehyde with an organic acid metal salt as a catalyst under weak acidity is extremely effective. .

It was completed after various researches (this is what we came up with).

In addition, the aim is to prevent the baking from deteriorating the properties such as the flexibility and solvent resistance of the paint film, and to prevent the baking from using an epoxy resin coating that has extremely excellent adhesion of the paint film to the object being coated. To provide a method for producing a phenolic resin for use.

[Structure of the invention]

The present invention is a phenolic resin for compounding epoxy resin paints, which is characterized by reacting phenols and formaldehyde under weak acidity using an organic acid metal salt.

In order to react phenols and formaldehydes using an organic acid metal salt as a catalyst, the preferred reaction conditions are that the molar ratio of phenols and form7k tehydes is 1.0 mole of phenol nuclei to 1.0 mole of formaldehyde.
0 mol or more and 3.0 mol or less, and the reaction temperature is 80 mol or more.
~140°C, the reaction time is 1~10 hours, and the resin formation reaction is completed while removing moisture and unreacted raw materials under normal pressure or reduced pressure.

Resol-type phenolic resins obtained by reacting phenols and formaldehydes with organic acid metal salts under weak acidity are used in two to three applications.This type of resol-type phenolic resin is used for molding For materials, there is Japanese Patent Publication No. 53-23861, and for self-hardening foundry sand, Japanese Patent No. 614946 and Japanese Patent No. 726584.
No. 753851.

Also for self-hardening refractories (two examples are JP-A-57-20
5357, Japanese Patent Application Laid-Open No. 57-205358, etc. For molding materials, a molding material made by kneading only the above resol type phenolic resin with a filler is used by heat-pressing and hardening, and for self-hardening foundry sand and self-hardening refractories, the above resol type is used as a binder. Since the phenol resin is used in combination with polyisoneanate and cured at room temperature, it is clear that the method of use is different from the phenol resin obtained by the method for producing a phenol resin for compounding epoxy resin paint according to the present invention. The use of phenolic resins as curing agents or crosslinking agents in epoxy resin paints is a completely new approach.

Examples of the phenols that can be used in the present invention include difunctional phenols such as orthocresol, para-cresol, para-ethylphenol, para-propylphenol, para-1fk phenol, para-ofnal phenol, and para-nonylphenol; Phenols with higher functionality include phenol, metacresol, 3.5-quinlenol, resorcinol, catechol, bisphenol A1, bisphenol F, and one or more selected from these.

Formaldehydes include formaldehyde, paraformaldehyde, triochitin, etc., and they can also be used in combination.

In order to react phenols and formaldehyde in the present invention (:), the organic acid metal salt used as a dicatalyst is one or more selected from divalent metal salts of organic acids; include carboxylic acid, naphthenic acid, sulfonic acid, and sulfinic acid, but carboxylic acid and naphthenic acid are particularly preferred, and types of divalent metals include lead, caruncum, Wangan, tin, zinc, copper, and barium magnencum. etc., but especially (dilead, manganese,
Zinc and barium are preferred. These catalysts are one or more selected from inorganic acids such as hydrochloric acid and sulfuric acid, which are commonly used as acid catalysts, and organic acids such as benzoic acid, salicylic acid, oxalic acid, maleic acid, and para-toluenesulfonic acid. It is also possible to use them together.

When phenols and formaldehyde are reacted under weak acidity using an organic acid metal salt as a catalyst, the amount of catalyst used is usually 0.0005 to 0.00% per mole C of phenol.
However, since the type of catalyst (= therefore the amount used varies greatly), it is appropriate to control the PH+ of the reaction system. In other words, the PH of one reaction system at 25°C 1= is preferably 3 Further (
: Preferably 4.5 to 6.0 (= It is preferable to react phenols and formaldehydes using a catalyst.

In addition, so that the pH of the reaction system is 3.5 to 6.8 (2 catalysts and 1. In addition to the organic acid metal salts (2) ordinary alkali metal hydroxides, carbonates, and alkaline earth metals), A small amount of one or more of basic catalysts such as hydroxides, ammonia oxides, and amine compounds can also be used in combination.

The phenolic resin obtained from the method C2 for producing a phenolic resin for blending in epoxy resin paints of the present invention is as follows.

After acetylation, the results of 'H-NMR (proton nuclear magnetic resonance) analysis showed that the sum of the number of moles of dimethylene ether bonds, methylene bonds, and methylol groups (the ratio of the number of moles of double dimethylene ether bonds was 20 % or more,
Preferably it is 30% or more. If it is less than 20%, the baking of the epoxy resin paint containing the phenol resin according to the present invention C will result in the adhesion of the paint film to the object to be coated.

The phenolic resin for compounding epoxy resin paints according to the present invention is acetylated and then subjected to 'H-NMR analysis (2). From the results of analysis, the binding molar ratio of formaldehyde to 1 mole of phenol nuclei (2 to 2) is preferably 3.0 or less. Yes, even (
= preferably 2.4 or less. Furthermore, the phenol resin for blending in epoxy resin paints of the present invention preferably has a number average molecular weight of 200 to 900, and more preferably 250 to 600, based on the results of OPC (gel permeation chromatography) analysis. The baking of the epoxy resin paint blended with the phenol resin obtained from the manufacturing method of the phenol resin for compounding the epoxy resin paint of the present invention (2) shows that the coating film has excellent adhesion to objects (2). A heat-reactive phenol resin obtained by reacting with a salt as a catalyst under a weak acidity (2) is compared with a conventional heat-reactive phenol resin obtained by reacting under a basic environment (2) with an alkaline catalyst, etc. This is due to the fact that the content of dibenzyl ether bonds is large, and in other words, the content of methylol groups is small.

Heat-reactive phenolic resins with a high content of dimethylene ether bonds are effective in improving adhesion to coated objects because they generate less condensation water when co-condensed with epoxy resins and cured. I can't help but think that I'm doing it. Furthermore, the baking of the epoxy resin paint containing a phenolic resin according to the present invention (= a paint film), and the baking of the conventional epoxy resin paint containing a phenol resin, shows a clear hue (= lighter color). The phenol resin obtained by reacting under weak acidity using an organic acid metal salt as a catalyst is oxidized (compared to the conventional phenol resin obtained by reacting under basic conditions using an alkaline catalyst etc.). There is little secondary coloration, and this effect is thought to be reflected in the hue (:) after co-condensation with the epoxy resin and curing.

Regarding the phenolic resin obtained by the method for producing a phenolic resin for blending into epoxy resin paints of the present invention, the solvents that can be used for dissolving the phenolic resin into a resin liquid for the purpose of improving the workability of blending into the epoxy resin are: , aromatics such as toluene and xylene, methyl cellosolve,
Cellosolves such as ethyl cellosolve and butyl cellosolve, cellosolve acetate, butyl cellosolve acetate, esters such as nibyl acetate, butyl acetate, ketones such as acetone methyl ethyl ketone, methyl isobutyl ketone, nclohexanone, isophorone, propyl alcohol, butyl alcohol, One or more types selected from alcohols such as diacetone alcohol.

〔Effect of the invention〕

The Evogin resin paint blended with the phenolic resin obtained from the present invention (method for producing phenolic resin for compounding epoxy resin paints according to 2) has excellent adhesion of the coating film to the coated object with respect to baking, and The film is extremely light in color.It also has good properties such as heat resistance, corrosion resistance, flexibility, and construction resistance. Demand for phenolic resins is expected to expand in the future.

In addition, the phenolic resin obtained by the method for producing a phenolic resin for blending in epoxy resin paints of the present invention can be used in various epoxy resins (compounded with It is possible to use.

The application of the Evokin resin paint blended with the phenolic resin obtained from the present invention (=method for producing phenolic resin for blending with epoxy resin paints (2) is for the inside of food cans, the inside of chemical cans, the lining of drums, and adhesive cans. It is used for adhesive brimers, for painting the inner and outer surfaces of crown caps, and for high-grade brimers for tableware, food appliances, etc.

Hereinafter, the present invention will be explained in detail by Examples (2).
The present invention is not limited to the embodiments.

Note that in these Examples and Comparative Examples (all "parts" and "%" described herein are 1 part by weight and t% by weight).

Example 1 Resin reactor equipped with stirring shaft, reflux condenser and thermometer (=
150 parts of phenol, 850 parts of para-cresol, 80%
583 parts of paraformaldehyde was charged and manganese acetate was added to adjust the pH of the reaction system to 6.20, while the temperature was gradually raised. After the temperature reached 110°C, the reaction was carried out under reflux under normal pressure for 5 hours, and further dehydration reaction was carried out under reduced pressure of 35 to 60 Torr. At 40 Torr, the internal temperature was 1
When the temperature reached 22°C, the dehydration reaction was completed to obtain a heat-reactive phenolic resin for epoxy resin paint formulation.
In order to improve the workability of blending into Evokin resin, we added and mixed phenolic resin for epoxy resin paint formulation (dimethyl ethyl ketone) to achieve a Gardner color number of 1.125℃ (-) with a non-volatile content (according to JIS K6909 +=) of 33%. A resin liquid was obtained. After acetylating phenol No. 1 fat for blending Evogin's honeydew, the results of 'H-NM analysis showed that the above 33% resin liquid 100F T2 contained methylol groups and Upon thermal decomposition of dimethylene ether bonds (contained 0.35 mol of biphasic active methylene groups).

Example 2 Resin reactor of the same type as Example 1 (=bisphenol A
1000 parts, 370 parts of 80% paraformaldehyde.

After charging 300 parts of ethyl cellosolve and adding 24% lead naphthenate to bring the pH of the reaction system to 5.6, the temperature was gradually raised.
Further, a dehydration reaction was carried out under normal pressure, and when the internal temperature reached 125°C (2), a heat-reactive phenol resin for compounding epoxy resin paints was obtained. Ethylceron lubricant was then added and mixed to obtain a Gardner color number. A resin liquid with a non-volatile content of 33% was obtained at 125°C.

'H-NMR analysis (according to 2, the above 33% resin liquid 1
00 F contained 0.28 mol of active methylene groups (= generated during thermal decomposition of methylol groups and dimethylene ether bonds).

Example 3 Baracresol 100 was added to the same type of m-lipid reactor as in Example 1.
0 parts, 400 parts of 88% paraformaldehyde, 550 parts of 37% formalin, and 300 parts of cellosolve acetate were charged, and after adding zinc acetate to adjust the pH of the reaction system to 5.1, the temperature was gradually raised. 3.5 under reflux under normal pressure
After the reaction was carried out for a period of time, dehydration was further carried out under normal pressure, and when the internal temperature reached 125°C (2), a heat-reactive phenol resin for epoxy resin paint formulation was added. Number of colors is 1, 12
A resin liquid with a non-volatile content of 33% was obtained at 5°C.
According to -NMR analysis, 100 g of the 33% resin solution contained 0.41 moles of active methylene groups generated during thermal decomposition of methylol groups and dimethylene ether bonds.

Example 4 A resin reactor of the same type as in Example 1 (= 1000 parts of Balatarsharifthylphenol, 520 parts of 85% paraformaldehyde, and 27,250 parts of Kin) was charged, and barium acetate was added to adjust the pH of the reaction system to 4.9. After that, the temperature was gradually raised to 123° C. (200° C.). The reaction was carried out under reflux under normal pressure for 5.0 hours, and the internal temperature was 123° C. under normal pressure. , internal temperature 1
When the temperature reached 27°C, a heat-reactive phenolic resin for blending with epoxy resin paints was obtained.

After that, the superposition ratio of xylene and butanol was 80:2.
Gardner color number is 1.125℃ by adding 0 mixed solvent.
A resin liquid with a nonvolatile content of 33% was obtained. 1H-NM
According to R analysis, 100 g of the above 33% resin liquid contains methylol groups and dimethylene ether bonds during thermal decomposition (=
It contained 0.33 mol of active methylene groups.

Comparative Example 1 Resin reactor of the same type as Example 1
parts, /(850 parts of Rafresol, 1 part of 37% formalin
After adding 260 parts of 25% caustic soda aqueous solution (parts) to make the reaction system basic, the reaction system was gradually raised to 100°C for 1 hour. After standing, the aqueous layer was separated and removed. Then, n-butanol 500
1 part and 500 parts of ginkgo were reacted at a temperature of 120° C. for 3 hours while removing moisture to obtain a resol type phenol resin. After that, a mixed solvent of the same weight of n-butanol and xylene was added, and the Gardner color number reached 3,125℃ (:
A resin liquid with a nonvolatile content of 33% was obtained. 'H-NMR
According to analysis (=), the above 33% resin liquid 100.P+2 contained 0.30 moles of active methylene groups (two phases) upon thermal decomposition of methylol groups and dimethylene ether bonds.

Comparative Example 2 Resin reactor of the same type as Example 1 (nibisphenol A
1000 parts, 37% formalin 800 parts, Kin 27
After adding 100 parts of 25% caustic soda aqueous solution to make the reaction system basic, the temperature was raised to 100°C.
The reaction was carried out for 1.5 hours. The mixture was neutralized with sulfuric acid, left to stand at room temperature, and then the aqueous layer was separated and removed. Then 50~60℃ hot water 100℃
The hot water washing was completed by adding 0 part of the solution, stirring it, and after setting i%, separating and removing the aqueous layer three times. followed by 25-80
A dehydration reaction was carried out under reduced pressure in Tart to obtain a thermally reactive phenol resin. Thereafter, xylene was added to obtain a resin liquid with a Gardner color number of 2,125°C (non-volatile content of 33%).
% resin liquid ioo y t = contained 0.28 mol of active methylene groups generated during thermal decomposition of methylol groups and dimethylene ether bonds.

Comparative Example 3 Resin reactor of the same type as Example 1 (= 1000 parts of para-butylphenol, 1195 parts of 37% formalin)
After adding 40 parts of 25% caustic soda aqueous solution and 30 parts of 25% aqueous ammonia to make the reaction system basic, the reaction system was reacted at 80° C. for 2 hours. The mixture was neutralized with hydrochloric acid and treated in the same manner as in Comparative Example 2 to obtain a heat-reactive phenol resin.

After that, xylene was added to increase the Gardner color number to 2°125.
A resin liquid with a nonvolatile content of 33% at ℃ (=) was obtained.

'H-NMR, analysis (Niyoreha, above 33% m fat liquid 10
0.9 +: is the active methylene group generated during thermal decomposition of the methylol group and dimethylene ether bond (= 0.33
It contained moles.

[Adjustment of Evokin resin paint]

A solution prepared by dissolving 700 g of bisphenol A-type Evokin resin (1,900 g) in 1,400 g of a mixed solvent of butyl cellosolve and xylene (;, 33 g of phenolic resin for compounding epoxy resin paints obtained in Examples 1 to 4) % resin liquid or the 33% resin liquid of the phenolic resin obtained in Comparative Examples 1 to 3 was heated to decompose the methylol group and dimethylene ether bond (- 3.0 mol of active methylene group (= equivalent number of grams) In addition, 2 grams of 5% phosphoric acid was added and mixed to prepare an Epokin resin paint.

[Test results of Epokin resin paint]

A tin plate with a thickness of 0.25 mm (2) The above adjustment paint was baked so that the coating film thickness was 5μ (applyed using a two-roll coater, baked at 210°C for 10 minutes, and prepared as a test piece. was created.

The test pieces were tested for coating film properties (coating film appearance, coating film adhesion, bending resistance, and solvent resistance), and the results are shown in Table 2.

Table 2 Note 1) Half mark Equimolar mixture of two types of resin liquid 2) Paint film appearance: naked eye (secondary observation 3) Paint film adhesion: paint film (with a cutter knife After scratching the book with perpendicular lines in the vertical and horizontal directions, apply cellophane tape afterward (= peeling off method) to observe the adhesion of the paint film and give a score.

l... Peeling part is less than 25% (good) 2.
・・・・・・ 25% or more but less than 50% 3.
... 150% or more (defective) 3) Flexibility:
The length of the crack that occurred was observed by bending the two test pieces 180 degrees so that the coating surface was on the outside and displaying it as a score.

1...Small, 2--Medium, 3...
...Large 4) Solvent resistance: Butanol or xylene at 25°C (; Visually observe the state of the coating after immersion for 14 days.

Tests/161 to 5 (= The epoxy resin paint blended with the resin liquid shown in Tests 46 to 9 (= The epoxy resin paint blended with the resin liquid shown in 2) had better paint film adhesion and better paint film appearance. The hue was clear (light color). Also, the bending resistance and solvent resistance (the two were comparable. Therefore, the phenolic resin obtained from the method for producing phenolic resin for compounding epoxy resin paints of the present invention (2) When baking the epoxy resin paint using the epoxy resin paint, the paint film had excellent adhesion to the object to be coated (2) and was light in color.

Claims (1)

[Scope of Claims] 1) A method for producing a phenolic resin for use in epoxy resin paint formulations, which comprises reacting phenols and formaldehyde under weak acidity using an organic acid metal salt as a catalyst. 2) The epoxy resin according to claim 1, wherein the organic acid metal salt used in the catalyst is one or more divalent metal salts selected from carboxylates and naphthenates. A method for producing phenolic resin for paint formulation.