JPS5840363A - Manufacture of water-dispersible epoxy paint composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to water-dispersible coating compositions based on epoxy resins. Epoxy resins are capable of forming tough coatings that are highly resistant to hydrolysis and chemical attack. Coatings exhibiting particularly high WLO resistance to hydrolysis are required, for example, as internal coatings for food and beverage cans that must withstand heating in contact with acidic aqueous solutions such as fruit juice or beer. be. The coating must not undergo hydrolysis to elute a substance that completely impairs the flavor of the food or beverage;
and (2) it must be able to withstand the conditions unavoidable during sterilization of food or beverages and (2) be capable of adhering satisfactorily to cans, usually made of tin or aluminum.

However, it is difficult to produce water-dispersible coating compositions containing epoxy resins. Volatile organic solvents
Furthermore, because the cost of organic solvents is rapidly increasing, their use is gradually decreasing. The invention can be applied to a substrate from a water-based diluent solution or stable dispersion.

When manufacturing a paint assembly based on epoxy resin,
purpose.

European Patent Publication Nos. 6334 and 6336 disclose a solvent-soluble carboxyl-functional polymer; an aromatic polyether having oxirane functionality; The mixture of aromatic bo-9 ethers constitutes at least 40% of the total resin solids, and the oxirane functionality is in a stoichiometric deficit of 1:2 to 12° relative to the carboxyl functionality in the carboxyl-functional polymer. The above esterification reaction 1. The oxirane functionality is reacted with the carboxyl functionality in an organic solvent medium in the presence of an amine esterification catalyst in an amount greater than 2 to the weight of the reactants to be esterified to completely convert the oxirane functionality into a commercially complete product. It was carried out at a high enough temperature to cause the disappearance of the oxidation gas, and the formation of 1.

A self-emulsifying epoxy ester copolymer characterized in that at least a portion of the carboxyl functionality in the polymer-epoxy resin hydroxy ester reaction product is reacted with a base to render the reaction product self-emulsifying in water. lol
- A method for producing the mixture is described. European Patent Application No. 6334 indicates that in order to avoid gelation 1a of the reaction mixture, it is necessary to use a high ratio of amine enetherification catalyst of 4 to 10 weight to reactants.

British Patent Publication No. 112,059,968 describes the treatment of epoxy resins with carboxylic acid in a mixture of water and organic solvents.
Other methods of making water-dispersible coating compositions are described by reacting a solution of a functional acrylic polymer and an amine. In this method too, a high proportion of amine is present in the reaction between the epoxy resin and the carboxyl-functional polymer.

Other methods for producing water-dispersible coating compositions based on addition polymers containing epoxy resins and carboxylic acid groups are available in the United States! f@4,212,781. In this method, epoxy m(I]&t is prepared in the presence of a 6-7 heavy benzoyl peroxide catalyst.

Reaction with an addition polymerizable material having at least a partial carboxylic acid functionality. In this invention, water-dispersible coating compositions are prepared from epoxy resins without requiring the use of such high levels of catalysts.

The method for producing a water-dispersible coating composition according to the present invention is performed at a high temperature and in the presence of an amine, with a molecular weight of 1. Epoxy resin composition with average epoxy functionality ti- of U~2.0 epoxide groups 40~9011rll19! and a carboxylic acid group-containing polymer of 10 to 60% by weight, and a ratio of carboxylic acid groups to epoxy groups of 15=1 to 20:1 to produce a water-dispersible coating composition.
It is characterized in that it is carried out in a water-miscible organic solvent mixture containing 5 to 3016 parts of water based on the total weight of the epoxy resin and the polymer containing carboxylic acid groups.

The epoxy resin preferably has an aromatic group bonded by an ether bond, and preferably has an average molecular weight t of 35 (10 or more, 2000 to 1
Examples of useful epoxy resins, particularly preferred are those having an average molecular weight of 2000, include bisphenol A
Examples include condensed glycidyl ethers of bisphenols such as 2,2-bis(4-hydroxyphenyl)propane, also known as 2,2-bis(4-hydroxyphenyl)propane. This engineered epoxy resin is [Epikote (OI) 7 J (
Epoxy functionality approximately 1.4'), rEpi
kote) 1009 J (x.

Poxy functionality approximately 1.2Jr Dow DER
668 J - “Dowdell 667” and “Dowdell 669”
It is sold under the trade name ``. Alternatively, a suitable epoxy resin such as Epicor+001, which has a relatively low molecular bias and a functionality of about 20, is produced by reacting an epoxy resin with a bisphenol such as bisphenol A can be manufactured. Mixtures of epoxy resins can also be used, for example resins such as Epicor 1001, which can be mixed with higher molecular weight resins. Highly functional epoxide base resin 1 For example, epoxy novolak resin is Epicoat 10
It can be used as an epoxy resin mixture having an average functionality IP of 1.0 to 2.0 epoxide groups per molecular weight.

Examples of polymers having carboxylic acid groups include olefinically unsaturated carboxylic acids, such as acrylic acid.

Addition polymers of methacrylic acid, maleic acid, itaconic acid or citraconic acid are preferred. Olefinically unsaturated #
lFi, olefinically unsaturated comonomers such as methyl methacrylate, gamma acrylate, ethyl acrylate, propyl acrylate, propyl methacrylate, butyl methacrylate.

Acrylic acid esters such as hexyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate;
Acrylamine methacrylate; styrene; or α-
Preferably, it is copolymerized with at least one type of methylsulfate.

As the copolymer, those containing 10 to 851 weight units of unsaturated carboxylic acid units are preferred, and those containing 30 to 60 weight units of unsaturated carboxylic acid units are particularly preferred. Carboxylic acid group t1! The ratio of carboxylic acid groups in the polymer to epoxide groups in the epoxy resin is preferably from 2:1 to 10:1. , ether alcohols such as 2-ethoxyethanol, 2-methoxyethanol or 2-butoxycetanol, alcohols such as ethanol or butanol.

and/or by radical polymerization in esters such as ethyl acetate, butyl acetate or 2-ethoxyethyl acetate. A small amount of an aromatic hydrocarbon, such as xylene or toluene, can be mixed with the water-miscible organic solvent, Kj.

Gelation in the subsequent esterification reaction could be avoided.

The reaction between the epoxy resin and the polymer having carboxylic acid groups can be carried out using an amine, preferably diethylaminoethanol,
Preferably catalyzed by a tertiary amine such as diethylaminoethanol, triethylamine, triethanol, hedimethylpenzylamine, N-ethylmorpholine or a2-(N,N-dimethylamino)-2-methylpropanol. The amount of amine added to the epoxy resin.

and 0.5 of the total weight of the polymer with carboxylic acid groups
Although it is possible to use higher proportions of the amine, preferably 3.0% and most preferably 1.0-2.011%, the inventors.

Such a large amount of amine is used when the reaction is carried out in the presence of 5 to 309 g, preferably 5 to 20 or 25, of water based on the total weight of the epoxy resin and the polymer with carboxylic acid groups. I found out that it wasn't necessary. If the amount of water present is less than 511 tIs, it is necessary to use a high proportion of amine to avoid gelation of the reaction mixture, and on the other hand.

If more than 30 parts by weight of water is present, larger amounts of amine and organic solvent are required to achieve economically desirable reaction rates.

The reaction between a polymer having carboxylic acid groups and an epoxy resin involves solution polymerization of the epoxy resin, optionally with additional organic solvent, in a water-miscible organic solvent such as those mentioned above. The amine catalyst and the water are premixed, preferably by mixing into a solution of the acrylic polymer produced by
and.

*Alternative to this method, it is preferable to add 1 lll of polymer t epoxy having carboxyl groups to the resin.
The reaction can also be performed by adding K, amine and water to the solution of the carboxyl-bearing polymer before mixing with ir.
It is preferable to carry out in the range of 80 to 120 degrees Celsius,
The reaction time, which is usually carried out at a temperature of about 95 to 100°C and under reflux, should be sufficient for substantially all the epoxy groups to react;
It is preferable that the acid value of the non-reactive raw bottom material is in the range of 1j30 to 100 for 8 hours.

Since the desired polymer having carboxylic acid groups and the desired epoxy resin will not form a compatible solution, the reaction mixture will be heterogeneous at the start of the reaction and will have a cloudy, dispersion appearance. In some cases, the reaction mixture is
As the reaction approaches the end point, the mixture becomes homogeneous and the brass alloy becomes transparent.

Once the reaction between the epoxy resin and the polymer containing carboxylic acid groups is complete, a base is generally added to the reaction product to at least partially neutralize the excess free carboxylic groups. Examples of bases include:

Ammonia or amines can be used, and it is generally preferred to use tertiary amines such as triethylamine, triethanolamine or dimethylacrylate, which are added to the reaction mixture in the form of an aqueous solution. In a preferred procedure, the base is sufficient to convert the coating composition into a stable dispersion with a continuous phase of water such that it can be further diluted with water without loss of dispersion stability. Add as a dilute solution in a suitable amount of water. The base is 4 of the free carboxylic acid groups in the reaction product.
0 to 120 m or 13016 t" Neutralization solution OK. It is preferable to use a sufficient amount of base and water.
The smooth white dispersion produced in 7cvk can also be used directly as a coating composition.

Alternatively, it can be further diluted with water to obtain a desired viscosity before use. If desired, the M formulation used in the preparation of the coating composition can be completely or partially removed and recovered from the composition.8 For example, bumeol, ethyl acetate and/or xylene can be It can be removed from the coating composition by distillation.

t) The coating composition of the invention is particularly suitable for coating on all sides of food and beverage cans, including fruit juice and beer cans, and is especially suitable for coating on solid wood, tinplate, steel and aluminum. Excellent adhesion tWL to metals such as metals and polymers used in food and beverage can base coatings;
The multilayer films of the coating composition of this invention adhere to each other.

The coating composition may contain an aminoplast resin or a phenolic resin, generally not necessary, but if desired, to provide additional crosslinking to the coating for curing. Aminoplast resins can be added to the coating composition before or after the neutralization and dilution step. Examples of suitable aminoplast resins include melamine formaldehyde resins, especially those resins consisting primarily of hequinamethoxymethylmelamine. can be mentioned. The coating composition is preferably applied to the substrate by spraying, but it can also be applied by dip coating, anionic electrocoating, direct or reverse roller coating, flow coating or rinse coating. In order to cure the coating film, it is desirable to heat it at 100 to 240°C for 10 seconds to 20 minutes, and the temperature is 150 to 210°C.
is particularly preferred.

Next, this invention will be explained by way of examples.

Example 1 An aqueous prebolimer solution was prepared by applying the following pressure.

1 n-butanol 4003 Methacrylic acid monomer 1854 Styrene monomer 805 Ethyl acrylate monomer
2106 This solvent mixture was charged to reaction 11 equipped with benzoyl peroxide 15 compounds (1) and (2), a stirrer, a reflux condenser, a basket tank, a flow regulator, a temperature needle, and an addition funnel. Heat to 120°C and add premixed monomers (compound 3
~S), solvent (71 silicate and peroxide β) was added over a period of 2 hours. batch temperature.

120°C during and for 2 hours after monomer addition
Afterwards the patch was cooled to 1-rich. The acrylic solution polymer thus produced is 36911Dll-shaped [
It had an acid value (based on solids) of 25,411 fKOH/f of 1.

An epoxy/acrylate polymer dispersion was prepared as follows.

(Epicote 1009) 3 Dimethylaminoethanol 294 Deionized water 2005 Dimethylaminoethanol 92゛6 Deionized water
- Seal 419 Acrylic Prepolymer Solution (1) - The solution was charged to a reactor equipped with a stirrer, a reflux condenser, a thermometer and an addition funnel, heated to -110°C, and the solution was The resin was melted. When all the epoxy resin was dissolved, the reactor mixture was cooled to 90°C and premixed water and amines (compounds 3 and 4) were added.
This mixture is then poured into a trench where the reaction is completed (generally
The mixture was refluxed for about 4 hours). Acid value of polymer 63t K
It was OH/l.

Premix the remaining dimethylaminoethanol and deionized water (Base 5 and 6) and heat to 70°C in a stainless steel temperer suitable for dispersing the ester grafted epoxy/acrylic polymer. did.

After completing the esterification step, the polymer was discharged into a mixture of water and amine. The dispersion was cooled to room temperature and filtered ready for use. This dispersion Fi, has a solids content of 69 at 25 m, a viscosity of 25 to 35 seconds by Ford Cup No. 4 method at 25°C, and a water to solvent ratio of 807.
It was 20.

Example 2 An aqueous prebolimer solution was prepared as follows.

1 n-butanol 10002 methacrylic acid 2263 styrene
47 4 Ethyl acrylate 416 Benzyl peroxide 9 Butanol (Compound 1)
t, stirrer, reflux condenser, monomer tank, #! Pour into a reactor equipped with a volume controller, temperature needle and 1m addition funnel.
Then, it was heated under reflux. Monomer and peroxide (compound 2
-5) were premixed in a seven-mer tank and added to the reactor over a period of 2 hours. Batch temperature r.

maintained at reflux temperature during monomer addition and for an additional 2 hours;
After this time the patch is cooled and butanol (compound 6
) was added to adjust the solid content to 20%. What is the acid value of Jin's acrylic polymer?

A 4 g, 9.5 mf KOH/f% epoxy/acrylate polymer dispersion was prepared in the following manner.

Number Ingredient Name Parts by weight 2 n-butanol 703 parts) (Epicote 1
007) 5 Dimethylaminoethanol 296 Deionized water 2007 Dimethylaminoethanol 878 Deionized water
4611930 Acrylic prevolamer, butanol and ethylene glycol butyl ether (d-fr, 1-3), reaction IsK equipped with a stirrer, reflux condenser, temperature needle and addition funnel, the mixture was brought to 110°C. The mixture was heated and treated with Ebosushi resin tWI. When all the epoxy* has been dissolved in the fat, the mixture t-90℃
Cool to, and.

Premixed water and amines (Seisuke 5 and 6) were added. The reaction mixture is then heated to reflux until the reaction is complete (generally about 4 hours), thereby reducing the
A polymer having an acid value of KOH/f was produced.

When the acid value reaches the above l[K,! A portion of dimethylaminoethanol (6) and deionized water (81) was added to the polymer solution, and the remainder of the VC was immediately added with deionized water. From this, the water to solvent ratio was 66/34 and 18 vI.
A dispersion was formed having a solid content of . The dispersion can be adjusted to the desired solids content and water/11 agent ratio by removing excess solvent by distillation.

Margin below

Claims (1)

[Claims] 1. 1.0 to 2 molecular weight at high temperature and in the presence of amines
An epoxy resin composition having an average epoxy functionality of 2,0 epoxide groups of 7 to 40 to 90 wt. and a carboxylic acid group-containing polymer of 10 to 60 wt. St, the ratio of the carboxylic acid groups to the epoxy groups being 1.5:1. A water-dispersible coating composition is prepared by reacting the water-dispersible coating composition at ~20:1. 1. A method for producing a water-dispersible coating composition, which is carried out in a water-dispersible organic solvent mixture. 2. The method according to claim 1, characterized in that the reaction is carried out in a water-miscible organic solvent mixture containing 5 to 20,916 parts of water based on the total weight of the epoxy resin and the polymer having carboxylic acid groups. Method. 3. The amount of amine present during the reaction is 0.5 to 3 based on the total weight of the epoxy resin and the carboxylic acid group-containing polymer.
．． 091! 8th 1st
or the method described in paragraph 142. 4. The amount of amine present during the reaction is 1.0 to 2 with respect to the total weight of the epoxy resin and the carboxylic acid group-containing polymer.
．． Claim wI1 characterized in that t- is 0-
The method described in Section 2 or IR Section 2. 5. The method according to any one of claims 111EI to 4, wherein the amine is a tertiary amine. 6. The epoxy resin contains an aromatic group bonded by an ether bond, and has an average molecular weight t- of 2,000 to 12,000.
The method according to any one of claims 1 to 5, characterized in that: 7. The carboxylic acid group-containing polymer is an olefinically unsaturated carboxylic acid of 10 to 85% by weight and an olefinically unsaturated comonomer! The method according to any one of claims w41 to 6, which is an addition copolymer consisting of at least 1990 to 15 weight of -. 8. The ratio of carboxylic acid groups in the carboxylic acid group-containing polymer to epoxide groups in the epoxy resin is 2:I~lU
: 1. The method according to any one of claims 11g1 step to 7. 9. 1.0 to 1 molecular weight at high temperature and in the presence of amine
An epoxy resin composition having an epoxy functionality of 2.0 epoxide groups 4 to 10 wt. and a carboxylic acid group-containing polymer 10 to 60 wt. st. ~20:l, the total weight of epoxy resin and carboxylic acid group-containing polymer is 5
A water-dispersible coating composition is prepared by reaction in a water-miscible organic solvent mixture containing ~30 g of water, and the coating composition is allowed to form a base and a continuous phase consisting primarily of water. A method for producing a stable dispersion type coating composition, which involves mixing with a sufficient amount of water to produce a stable dispersion type coating composition. 10. The method according to claim 9, wherein the base is a tertiary amine. 11. A patent claim characterized in that the amount of base used is sufficient to neutralize 40-13096t of free carboxylic acid groups in the reaction product of the epoxy resin and the polymer containing carboxylic acid groups. The method according to item 9 or 10. α, organic solvent t used in paint assembly form WxK. 12. A method according to any one of claims 9 to 11, characterized in that the composition is completely or partially removed. 13. The method according to claim 12, characterized in that the organic solvent t is removed from the coating composition by azeotropic distillation.