JPH0195164A - Phenolic resin composition for paint - Google Patents

Abstract

PURPOSE:To provide the title composition excellent in boiling water resistance, etc., and suitable as a curing agent for a water-based paint for an inner surface of a can, by constituting it from a bisphenol A-derived phenolic resin specified in the average number of bisphenol nuclei and the number of methylol groups. CONSTITUTION:A bisphenol (e.g. bisphenol A) is reacted with a formaldehyde (e.g., formalin) to produce a bisphenol-derived high-MW phenolic resin having the average number of bisphenol nuclei of 8-25 and 0.1-2 methylol groups per bisphenol nucleus. This phenolic resin is used as a principal component to produce a phenolic resin composition for paint. When this resin composition is used as a curing agent of a water-based epoxy phenol paint for an inner surface of a can, it can give excellent properties such as low yellowness of film, small KMnO4 consumption and excellent flavor resistance and processability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a phenolic resin composition for paint. More specifically, when used as a curing agent in an epoxy-phenolic can interior water-based paint, boiling water resistance, KMn
The present invention relates to a phenolic resin composition for paints that can provide extremely excellent properties in O4 consumption, anti-flare/hardening properties, processability, and curability.

(Prior art) As is well known, the performance of epoxy-phenol paints is
It is greatly influenced by the properties of the phenolic resin blended. In reality, the balance of performance changes depending on the type and composition ratio of the phenol component used, the type and amount of the catalyst, the amount of formaldehyde, the epoxy/phenol ratio, etc.
Various phenolic resins are used depending on their respective uses. However, conventional resol type fer/fer resins have a relatively low molecular weight, with a weight average molecular weight of about 300 to 000 tons, so they have been used as epoxy-phenol paints and as curing agents for water-based paints on the inside of cans. In this case, KMnO4 consumption is high, and there are problems with flavor resistance, hardenability, and boiling water resistance. In addition, in order to solve these characteristics, there are examples of producing high molecular weight resol type phenolic resins through a one-step reaction using ammonia as a catalyst, but because the methylol group concentration is low, curability, boiling water resistance, K
There are problems with M n O4 consumption and anti-flare properties,
Furthermore, because of the ammonia aresol resin, the yellowing of the coating film is also significant, and it seems that no solution to this problem has yet been reached.

(Problems to be Solved by the Invention and Means for Solving the Problems) Therefore, the present inventors have discovered that when used as a curing agent for an epoxy-phenol water-based paint for the inside of a can, the yellowing of the paint film and the Intensive research has been carried out to develop a phenolic resin composition that consumes only a small amount of KM nO4 and can provide excellent flavor resistance, processability, boiling water resistance, and curability.

As a result, when a phenol resin composition that is a bisphenol type high molecular weight phenol resin and has a specific amount of methylol groups is used as a curing agent for a water-based paint on the inside of a can,
The present invention was achieved based on the discovery that KMnO4 consumption is small and performance such as flavor properties, curing properties, boiling water resistance, processability, etc. are well-balanced.

That is, the present invention is a reaction product of bisphenols and formaldehyde, and the average bisphenol 41
The present invention relates to a phenolic resin composition for paint having a compound 'II of 8 to 25 and an average of 0.1 to 2.0 methylol groups per bisphenol.

Examples of bisphenols used in the present invention include bisphenol A, bisphenol B, and bisphenol F, which may be used alone or in combination, and some of these may be supplemented with cresol, pt-butylphenol, salicylic acid, etc. You can also use the ones that exist.

Moreover, formalin, paraformaldehyde, etc. can be used as formaldehyde.

In order to obtain the phenolic resin composition for paint of the present invention, for example, the following three-step process can be used.

In the first step, formaldehyde is added to bisphenols to form methylol, in the second step, the molecular weight is increased, and in the third step, formaldehyde is added again to form methylol.

This method will be explained in more detail.

In the first step, the reaction between bisphenols and formaldehydes is carried out in the presence of a basic catalyst, and the bisphenols are methylolated, but in the first step, it is preferable to react all the formaldehydes used. In the first step, in addition to methylolation of bisphenols, a portion of methylolated bisphenols may be subjected to dehydration condensation.

Solvents used in this first step include aromatic hydrocarbon solvents such as xylene, toluene, benzene, and alkylbenzene, aliphatic hydrocarbon solvents such as pentane and heptane, alicyclic hydrocarbons such as cyclohexane, and water. However, it is particularly preferable to use water in terms of cost and ease of purification of the final product.
By using the above solvent, the reaction system becomes a heterogeneous reaction, the addition of formaldehyde to bisphenols is promoted, and the methylolation reaction is carried out in a short time. The amount of these solvents used is the same as that of bisphenols.
0% to 200% by weight is preferred, and 1001f! ,1
% to 150% by weight is more preferred. The amount of solvent used is 5
If it is less than 0% by weight, the viscosity will increase as the reaction progresses, causing problems in production, while if it exceeds 200% by weight, it will take too much time to ultimately separate and recover the solvent, and productivity will deteriorate significantly. There is a tendency to

Furthermore, as the basic catalyst, those commonly used for synthesizing resol type phenol resins can be used. for example,
alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide; alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide; and basic metal salts such as trisodium phosphate; Amines such as triethylamine, trimethylamine, ethanolamine can be used.

The amount of the alkali catalyst used is preferably 0.005 to 0.2 mol per mol of bisphenols.

If it is less than 0.005 mol, the methylolation reaction will be slow and productivity will be poor, while if it exceeds 0.2 mol, the reaction will be too rapid and difficult to control.

The amount of formaldehyde to be used is 1.5 to 3.0 mm in terms of formaldehyde per 1 mole of bisphenols.
0 mol is preferable, and 1.5 to 2.0 mol is more preferable. The converted amount of formaldehyde used (molar ratio) is 1
．． If the amount is less than 5 moles, it is difficult to sufficiently increase the molecular weight in the second step, whereas if it exceeds 3 moles, the methylolated bisphenols, which have a high molecular weight, are dehydrated and condensed in an acidic atmosphere to increase the molecular weight. Through this second step, it is possible to reliably increase the molecular weight of the resol type phenolic resin.

An acidic catalyst is used to create an acidic atmosphere.As acidic catalysts, known ones that are usually used when synthesizing novolac type phenolic resins, such as inorganic acids such as sulfuric acid and hydrochloric acid, oxalic acid, phthalic anhydride, and formic acid, can be used. Organic acids such as can be used. The amount of acidic catalyst to be used is preferably the amount required to equivalently neutralize the alkaline catalyst used in the first step plus an amount of 0.005 to 1.0 mol per 1 mol of bisphenols. .

In the reaction in the second step, the bisphenols used 1
0.2 to 3.0 mol, preferably 0.8 to 1 mol
．． It is desirable to allow the reaction to occur until 5 moles of water have been dehydrated. The dehydration ratio is 0.2 per mole of bisphenols.
When the amount is less than mol, the molecular weight cannot be sufficiently increased, and when it exceeds 3 mol, the viscosity becomes abnormally high, and the inner wall of the reaction vessel is seriously contaminated. This second
The molecular weight (degree of condensation) of the phenolic resin covered by the process is controlled. The degree of condensation at this time is desirably an average number of bisphenol nuclei of 8 to 25, preferably 10 to 20.The increase in molecular weight in the second step is achieved through self-condensation of methylol groups (-CH20CH2).
Alternatively, a condensate of high molecular weight bisphenols formed by hydrogen abstraction of a methylol group and a benzene ring is reacted with formaldehyde in a basic atmosphere to convert the high molecular weight condensate of bisphenols into methylol. It is done.

This step is carried out under a basic atmosphere, and a basic catalyst is used to create a basic atmosphere. As the basic catalyst, the same basic catalyst that can be used in the first step of the present invention is used. can. The amount of basic catalyst used in this step is 0.005 mol per mole of bisphenols, which is the amount necessary to neutralize an equivalent amount of the unneutralized acidic catalyst among the acidic catalysts used in the second step. It is desirable to add an amount of 0.2 mol to 0.2 mol.

In addition, the amount of formaldehyde used in this step is 0.00% in terms of formaldehyde per mole of bisphenols.
The amount is preferably 1 to 2.0 mol, preferably 0.2 to 1.0 mol.

By changing the degree of methylolization in this third step, it is possible to obtain a phenol resin that meets the required performance as appropriate.

Said 1st. Second. By performing the third step, the average number of bisphenol nuclei is 8 to 25, more preferably 10 to 2.
It is possible to obtain a phenolic resin composition for coatings having an average of 0.1 to 2.0, more preferably 0.2 to 1.0 methylol groups per bisphenol nucleus. It is preferable to neutralize the base remaining in the composition obtained in the third step with an acid, and further perform dehydration, solvent removal, and elimination of m-isolated formaldehyde.

In addition to the above-mentioned method, the method for producing the phenolic resin composition for paints of the present invention includes reacting 2 moles or more of formaldehyde with 1 mole of bisphenol in the first stage step to highly methylolize the phenolic resin composition. There are methods to increase the molecular weight of a substance in the second step, but these methods make it difficult to control the reaction.

The average number of bisphenol nuclei obtained as described above is 8 to 25, preferably 10 to 20, and the average number of methylol groups per bisphenol nucleus is 0.1 to 2.0, preferably 0.2 to 1. When the phenolic resin composition for paints of the present invention having 0 is used as a curing agent for a water-based paint on the inside of a can, it consumes less KMnO4 and has extremely excellent performance in terms of flavor properties, curing properties, boiling water resistance, processability, etc. It is something that can be given. When the average number of bisphenol nuclei is less than 8, KMnO4 consumption increases, and flavor resistance and processability tend to deteriorate.On the other hand, when it exceeds 25, the viscosity increases significantly, making handling difficult. In addition, if the number of methylol groups is less than 0.1 on average per bisphenol nucleus, curing properties and boiling water resistance will be poor, and - actual average 2
．． When the number exceeds 0, processability and flavor properties tend to deteriorate.

Note that the average number of methylol groups relative to the bisphenol l nucleus exhibits particularly excellent performance as a curing agent in infrared spectrum and free forma epoxy phenol paints, but it is difficult to cure agril-based, alkyd-based, polyester-based, etc. that have hydroxyl groups. It also exhibits excellent performance as an agent.

Furthermore, the phenolic resin composition for paints of the present invention can be used not only in water-based paints but also in organic solvent-based paints.

Next, the present invention will be further explained by giving examples. Further, "parts" and "r%" described in each example and comparative example indicate "parts by weight" and "wt%".

Example 1 228 parts of bisphenol A, 228 parts of water, 2 parts of sodium hydroxide, and 162 parts of 37% formalin water were charged into a reaction vessel equipped with a stirrer and a reflux condenser, heated to 80 to 85°C, and reacted for 2 hours. I let it happen. Next, 4 parts of sulfuric acid was added at the same temperature to advance the reaction, and 20 parts of water was dehydrated by heating over 4 hours. Thereafter, 9 parts of sodium hydroxide and 81 parts of 37% formalin water were added, and methylolization was carried out at 80°C for 1 hour.

After that, sulfuric acid was added to neutralize excess sodium hydroxide to make the PL=6 to 7. Then, the degree of vacuum is 700 mm.
The mixture was heated with Hg to perform dehydration, solvent removal, and free formaldehyde, and when the concentration reached 70%, it was diluted to 60% with n-butanol. The properties of the obtained high molecular weight resol type phenolic resin were as follows.

Bisphenol A Average number of nuclei: 15 (calculated by GPC) Bisphenol A: Methylol group concentration per nucleus is 0.
8 (Calculated from infrared spectrum and NMR measurement of free formaldehyde amount) Example 2 228 parts of bisphenol A, 228 parts of water, 3 parts of sodium hydroxide, and 121 parts of 37% formalin water were placed in a reaction vessel equipped with a stirrer and a reflux condenser. The mixture was charged, heated to 80 to 85°C, and reacted for 2 hours. Next, 4 parts of sulfuric acid was added at the same temperature to advance the reaction, and 18 parts of water was dehydrated by heating over 2 hours. Thereafter, 9 parts of sodium hydroxide and 81 parts of 37% formalin water were added, and methylolization was carried out at 80°C for 1 hour.

After that, sulfuric acid was added to neutralize excess sodium hydroxide to make the PL=6 to 7. Then, the degree of vacuum is 700 mm.
The mixture was heated with Hg to perform dehydration, solvent removal, and free formaldehyde, and when the concentration reached 70%, it was diluted to 60% with n-butanol. The properties of the obtained high molecular weight resol type phenolic resin were as follows.

Bisphenol A Average number of nuclei 10 Bisphenol A Concentration of methylol group per nucleus 0.
8 Example 3 228 parts of bisphenol A, 228 parts of water, 2 parts of sodium hydroxide, and 121 parts of 37% formalin water were charged into a reaction vessel equipped with a stirrer and a reflux condenser, and heated to 80 to 85°C for 2 hours. Made it react. Then, 4 parts of sulfuric acid was added at the same temperature to advance the reaction, and 18 parts of water was dehydrated by heating over 4 hours. Thereafter, 9 parts of sodium hydroxide and 162 parts of 37% formalin water were added, and methylolization was carried out at 80° C. for 4 hours. Thereafter, sulfuric acid was added to adjust the pH to 6 to 7 to neutralize excess sodium hydroxide. Then, the degree of vacuum is 700 mm.
The mixture was heated with Hg to perform dehydration, solvent removal, and free formaldehyde, and when the concentration reached 70%, it was diluted to 60% with n-butanol. The properties of the obtained high molecular weight resol type phenolic resin were as follows.

Bisphenol A Average number of nuclei: 11 Bisphenol A: Methylol group concentration per nucleus is 1.
5 Comparative Example 1 228 parts of bisphenol A, 228 parts of n-butanol,
5.0 parts of ammonia and 324 parts of 37% formalin water were charged into a reaction vessel equipped with a stirrer and a reflux condenser.
The mixture was heated to ℃ and reacted under reflux for 6 hours. Then,
After discharging the water to be separated, the degree of vacuum is 700 mmHg.
The mixture was heated to perform dehydration, removal of solvent, and removal of formalin. When a concentration of 70% was reached, it was diluted to 60% with n-butanol.

The properties of the obtained resol type phenolic resin were as follows.

Average number of nuclei 6 Methylol group concentration 0.5 Comparative Example 2 228 parts of bisphenol A, 228 parts of water, 2 parts of sodium hydroxide, and 162 parts of 37% formalin water were charged into a reaction vessel equipped with a stirrer and a reflux condenser. The temperature was raised to ~85°C and the reaction was allowed to proceed for 2 hours. Then 9 parts of sodium hydroxide, 3
81 parts of 7% formalin water was added, and methylolization was carried out for 1 hour using go''c. After that, sulfuric acid was added to neutralize excess sodium hydroxide to bring the PL to 6 to 7. Then, the degree of vacuum was reduced to 700 mmHg. The mixture was heated to perform dehydration, solvent removal, and free formaldehyde.When the concentration reached 70%, it was diluted to 60% with n-butanol.

The properties of the obtained high molecular weight resol type phenolic resin were as follows.

Bisphenol A Average number of nuclei 1.5 Bisphenol A Concentration of methylol group per nucleus 2.8 Comparative Example 3 228 parts of bisphenol A, 228 parts of water, 2 parts of sodium hydroxide, and 202 parts of 37% formalin water were mixed with a stirrer and The mixture was charged into a reaction vessel equipped with a reflux condenser, heated to 80 to 85°C, and reacted for 3 hours. Next, 4 parts of sulfuric acid was added at the same temperature to continue the reaction, and 20 parts of water was dehydrated by heating over 4 hours. Thereafter, in order to neutralize excess sulfuric acid, sodium hydroxide was added to adjust the pH to 6 to 7. Then the degree of decompression is 700 m.
The mixture was heated at mHg to perform dehydration, solvent removal, and elimination of formaldehyde. When the concentration reaches 70%, n-
Diluted to 60% with butanol. The properties of the obtained high molecular weight resol type phenolic resin were as follows.

Bisphenol A Average number of nuclei 15 Bisphenol A Concentration of methylol group per nucleus 0.
06 Comparative Example 4 228 parts of bisphenol A, 228 parts of water, 2 parts of sodium hydroxide, and 162 parts of 37% formalin water were charged into a reaction vessel equipped with a stirrer and a reflux condenser, and heated to 80 to 85°C for 2 hours. Made it react. Thereafter, sulfuric acid was added to adjust the pH to 6 to 7 to neutralize excess sodium hydroxide. Then, the mixture was heated at a reduced pressure of 700 mmHg to perform dehydration, solvent removal, and free formaldehyde. When the concentration reached 70%, it was diluted to 60% with n-butanol.

The properties of the obtained high molecular weight resol type phenolic resin were as follows.

Bisphenol A Average number of nuclei: 1.2 Methylol group concentration per bisphenol A nucleus: 2.0 Application examples 1 to 7 Using the phenol resins obtained in Examples 1 to 3 and Comparative Examples 1 to 4 above, the following procedure was performed. A water-based paint was prepared, and the water-based paint was applied to one side of a 100 l aluminum foil to a thickness of 8 to 10 l, and then dried at an ambient temperature of 200°C for about 30 seconds. Furthermore, the above-mentioned water-based paint was applied to the back side to a thickness of 8 to 10 l, and then dried at an ambient temperature of 200''C for about 80 seconds to prepare a test panel for a water extract flavor test.

Further, the above water-based paint was applied on a #25 tin plate to a thickness of 8~10μ, and then the ambient temperature was 200°C! About 2
The test panel was prepared by drying for a minute. Test results first
Shown in the table.

[Preparation of water-based paint] Formulation (2) Epoxy resin solution (Note 2) 283 parts (3)
n-Butanol 86 parts (4) 2-Butoxychetanol 47 parts (5) Deionized water
3.2 parts (6) dimethylaminoethanol
5.3 parts (7) dimethylaminoethanol 9
．． 5 parts (9) 646 parts deionized water
Total: 1260 parts (Note 1) Acrylic resin with an acid value of 390 and solid content of 30% copolymerized with 174 parts of methacrylic spirit, 87 parts of styrene, and 29 parts of ethyl acrylate (Note 2) Epicor) 828 (epoxy resin manufactured by Shell) 90% epoxy resin solution prepared by reacting 500 parts of bisphenol A, 286 parts of tri-n-butylamine, and 86 parts of methyl isobutyl ketone.
It was heated to 15°C to dissolve the resin component. After dissolving 1
Cool to 05°C, add (5) to (6) in order,
It was kept at °C for 3 hours. The reaction product is acrylic resin/
The solid content weight ratio of the epoxy resin is 15/85. The reaction was tracked by measuring the acid value, and the acid value was 51 at the end of the reaction. Then, after 3 hours, (7) was added, and after 5 minutes, (8) was added.
) was added followed by (9) over a period of 30 minutes to obtain a stable aqueous paint with a solids content of 25%.

The tests in Table 1 were conducted according to the following method.

3. Adhesion Use a knife to make 11 vertical and horizontal cuts, each about 1.5 mm wide, on the painted surface of the test panel painted on tinplate. A cellophane adhesive tape with a width of 24 mm is attached to the sample, and when it is strongly peeled off, the adhesion of the goblin area is observed.

0: No peeling at all, Δ: Slight peeling, ×: Significant peeling.

宸4 #Footeng A test panel painted on water-based tinplate was treated underwater at 100"C for 30 minutes, and the coating film was visually and peeled off with cellophane adhesive tape (
Judgment is made using the same evaluation as for adhesion in 03).

15 KMnO4 consumption Put 100 l aluminum foil coated with various water-soluble paints into a heat-resistant glass bottle so that the coating area: activated carbon treated tap water is 1 cm": 1 + a/, cover with a lid, and heat at 125°C.
The sample was treated for 30 minutes and measured according to the test method described in the Food Sanitation Act (Ministry of Health and Welfare No. 434). The consumption amount is expressed in ppm.

Zero〇 Water Extract Flavor Type A piece of aluminum foil coated with various water-based paints was placed in a heat-resistant glass bottle so that the applied area: tap water treated with activated carbon was 4CI112 = 1-, the lid was closed, and the bottle was heated at 100℃-
After 30 minutes of sterilization, a flavor test of the liquid contents is conducted.

O: No change at all, Δ: Slight change, ×: Significant change.

Processability Using a special fold-type DuPont impact tester, a painted sample of tin plate folded in half was placed at the bottom, and an iron drill weighing 1 kg with a flat contact surface was dropped from a height of 50 cm. Measure the length of the crack in the paint film that occurs at the bend.

O: 0~10rnffi, Δ: lO~20ff1m, X
: 20 mm or more 8 Gel fraction A #25 tin plate coated with various water-based paints was placed in a container equipped with a rapid flow cooler so that the coating surface: chloroform was 1 cffi2: 14, heated, and from the start of reflux. The amount of residue after 1 hour is expressed as a percentage.

Clothing 9 Δb (Degree of coloration of coating film) A test panel coated on a tin plate was visually observed to evaluate the degree of coloration.

0: Almost no coloring ×: Significantly colored

Claims (1)

[Claims] It is a reaction product of bisphenols and formaldehyde, and has an average number of bisphenol nuclei of 8 to 25, and an average of 0.1 to 2.0 methylol groups per bisphenol nucleus.
A phenolic resin composition for paint having 0 pieces.