RU2280661C1 - Water-dilutable composition for protective coatings - Google Patents

Abstract

FIELD: beverage industry.

SUBSTANCE: invention relates to production of water-dilutable composition used, in particular, for protecting inside surfaces of aluminum cans for beer, soda and soda-free low-alcohol and soft drinks. Composition contains, wt %: epoxide oligomer with molecular mass 2000-10000 - 5,7-9,0, unsaturated monomers 10.0-22.0, benzoyl peroxide 1.2-3.2, organic solvents 9.0-14.5, neutralization agents 1.4-5.0, distilled water 46.5-69.9, epoxide oligomer with molecular mass 200-500, and, as curing agent, water-dilutable melamine-formaldehyde oligomer 0.5-1.2, said unsaturated monomers being selected from methacrylic acid, methyl methacrylate, styrene, and ethyl acrylate.

EFFECT: increased continuity of coating and resistance to hydrolysis on storage, which assures preservation of sedimentation stability and invariability of dispersion composition over at least two years.

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Description

The invention relates to water-borne paints and varnishes based on modified epoxy oligomers and can be used, in particular, to protect the inner surface of aluminum cans for drinks.

Hydrolysis-resistant aqueous protective varnishes are known for coating metal cans, and the recommended polymer for these formulations contains the copolymerization product of a high molecular weight epoxy ester and unsaturated monomers in the presence of a peroxide initiator [US Patent No. 5792804, 1998]. The composition contains in its composition the following components (in wt.%):

terephthalic acid 4.15 trimellitic anhydride 0.69 adipic acid 5.2 pentaerythritol 0.12 diethylene glycol 7.48 epoxy oligomer (M = 2000) 13.3 butylene glycol 4.38 N, N-dimethylbenzylamine 0,035 acrylic acid 2,8 styrene 2.85 butyl acrylate 5.65 dibenzoyl peroxide 0.3 methyl ethyl ketone 2.16 dimethylethanolamine 0.9 distilled water 49,985

The main disadvantage of this material is the multi-stage process of base synthesis and the complexity of controlling the performance of intermediates at various stages.

Closest to the invention is a water-borne coating composition (US Patent No. 5,508,325, 1996), containing as a film-forming carboxyl-containing modified epoxy acrylic copolymer as a product of sequential interaction of an epoxy oligomer containing more than one epoxy group per molecule with a molecular weight of 2000-10000, with unsaturated monomers some of which are carboxyl functional. This product is taken as a prototype. This composition is prepared in the following ratio

film-forming components (in wt.%):

epoxy oligomer (2000-10000) 6.0-7.5 unsaturated monomers 9.0-10.5 benzoyl peroxide 0.6-1.2 organic solvents 7.5-10.0 neutralizing agents 2.0-3.0 water 70.0-73.0 epoxy oligomer (200-500) 0.8-2.5

The disadvantage of this invention is the insufficiently high continuity of the resulting coatings, which is especially important when applying this varnish composition to the inner surface of the food packaging.

The technical result of the invention is to obtain a varnish capable of forming coatings with higher continuity while maintaining other, no less important characteristics of both the composition and the coatings.

The technical result of the invention is achieved in that the water-borne composition for protective coatings includes epoxy oligomers, unsaturated monomers: methacrylic acid, methyl methacrylate, styrene, ethyl acrylate, neutralizing agents, organic solvents, benzoyl peroxide and distilled water, the composition additionally contains a curing agent, water-soluble, finely divided oligomer the following ratio of components (wt.%):

epoxy oligomer (M = 2000-10000) 5.7-9.0 unsaturated monomers 10.0-22.0 benzoyl peroxide 1.2-3.2 organic solvents 9.0-14.5 neutralizing agents 1.4-5.0 distilled water 46.5-69.9 epoxy oligomer (M = 200-500) 1.0-1.2 melamine-formaldehyde oligomer (water) 0.5-1.2

As a high molecular weight epoxy oligomer, it is proposed to use oligomers of the DER 669 and EPON 1009 brands, which are diane epoxy oligomers obtained by the fusion of a low molecular weight epoxy oligomer and diphenylol propane and having a molecular weight of 4200-4300. A low molecular weight epoxy oligomer is proposed to be used with DER 330 and ED-20 grades (molecular weights 340-350 and 380-430, respectively). Water-borne melamine-formaldehyde oligomer is a condensation product of formaldehyde and melamine with a high degree of butanolization (grade K-421-02).

The copolymerization product of an epoxy oligomer (M = 2000-10000) with unsaturated monomers such as methacrylic acid, styrene, methyl methacrylate, ethyl acrylate is used as the basis of the composition. As organic solvents are used n-butanol, butyl cellosolve, hexyl cellosolve. Triethylamine, diethanolamine, ammonia, dimethylethanolamine are used as neutralizing agents.

Information about the components of the composition: n-butanol (GOST 5208-81 with amendment 1-3), butyl cellosolve (TU 6-01-646-84), ED-20 (GOST 10587-84), methyl methacrylate (GOST 20370-74) , methacrylic acid (TU 6-02-59-89), styrene (GOST 10003-90 with amendment 1), benzoyl peroxide (GOST 14888-95), diethanolamine (TU 6-09-2652-91), triethylamine (GOST 9966-88), dimethylethanolamine (TU 6-02-1086-91), ammonia 25% aqueous solution (GOST 3760-64), distilled water (GOST 6709-72), melamine-formaldehyde oligomer K-421-02 (TU 6 -10-1022-78).

The invention is illustrated by the following examples.

Example 1 (prototype).

The aqueous dispersion of the grafted epoxy acrylic copolymer is obtained from the following starting components:

Group Content, wt.% Component Name BUT 6.0 Epon 1009, high molecular weight epoxy oligomer 2.1 Hexylcellosolve 2.1 Butyl cellosolve 4.7 n-butanol B 4.1 Methacrylic acid 3,1 Styrene 3,1 Ethyl Acrylate 0.8 Benzoyl Peroxide, 78% Aqueous Solution AT 1.9 Dimethylethanolamine 0.8 Ammonia (25% aqueous solution) 20.6 Distilled water G 30.9 Distilled water D 0.9 DER 330, low molecular weight epoxy oligomer (epoxy equivalent weight 187) 18.9 Distilled water

The components of group (A) are heated to 117 ° C in the presence of an inert gas, such as nitrogen, and maintained at this temperature during the addition of the components of group (B) for 2.5 hours. After adding the components of group (B), the reaction mixture was incubated for 30 minutes and cooled to 100 ° C. The components of group (B) are then added to the system over 10 minutes to disperse the copolymer in water. Then the component of group (G) is added to the reaction mass. Next, the components of group (D) are added to the system and kept at a temperature of 90 ° C for two hours.

Example 2

In a four-necked flask with a volume of 500 cm ³ , equipped with a stirrer, thermometer, reflux condenser, dropping funnel, when inert gas is introduced, 60 g of DER 669 epoxy oligomer, 50 g of n-butanol, 50 g of butyl cellosolve are placed and the mixture is heated to a temperature of 116-117 ° FROM. Dissolution of the epoxy oligomer in a mixture of organic solvents is carried out for 30 minutes. Next, a preformed mixture of unsaturated monomers containing 30 g of styrene, 30 g of methyl methacrylate, 40 g of methacrylic acid and 8 g of benzoyl peroxide is added dropwise through a dropping funnel over a period of 1.5-2.0 hours; the temperature is maintained at 115-120 ° С. . After adding the entire mixture, the reaction mass is maintained at the same temperature for 30 minutes. The product obtained at this stage is a light yellow solid polymer at room temperature. Then the polymer is cooled to 100 ° C and, with vigorous stirring (300 rpm) and inert gas flow through a dropping funnel, a neutralizing mixture consisting of 200 g of water, 20 g of diethanolamine and 7.5 g of ammonia is added. The resulting product with vigorous stirring is kept for 1-1.5 hours at a temperature of 80-90 ° C. Then, with a working stirrer, a mixture is added containing 8 g of DER molecular weight low molecular weight epoxy oligomer, 330.5 g of water-borne melamine-formaldehyde oligomer K-421-02 and 150 g of water. At a temperature of 90 ° C, the product is incubated for 1.5-2 hours. The mixture is then cooled with stirring to room temperature.

Examples 3-5.

According to the procedure described in example 2, water-borne epoxy acrylic compositions are prepared using other ratios of reacting substances, and triethylamine, dimethylethanolamine, etc. can also be used as neutralizing agents.

The ratio of the starting reagents and the properties of the coatings for examples 1-5 are shown in table 1.

Table 1 Component Name Component Content Composition number one 2 3 four 5 % mass % mass % mass % mass % mass epoxy oligomer (DER 669) - 5.7 6.8 8.2 9.0 epoxy oligomer (EPON 1009) 6.0 - - - - butyl cellosolve 2.1 7.0 6.0 6.0 7.5 n-butanol 4.7 2.0 4.2 6.8 7.0 hexyl cellosolve 2.1 - - - - methacrylic acid 4.1 4.1 4.0 5,0 6.0 methyl methacrylate - 3.6 8.0 8.4 7.8 styrene 3,1 2,3 3.6 4.7 8.2 ethyl acrylate 3,1 - - - - benzoyl peroxide 0.8 1,2 1.8 2,5 3.2 distilled water 70,4 69.9 62.1 51.1 46.5 diethanolamine - 1,1 - - 0.5 triethylamine - - 1,0 - - ammonia (25% aqueous solution) 0.8 1,1 - 2,4 0.7 dimethylethanolamine 1.9 0.5 0.4 2.6 1.7 epoxy oligomer (DER 330) 0.9 1,0 0.3 - 0.9 epoxy oligomer ED-20 - - 0.9 1,1 0.2 melamine-formaldehyde oligomer K-421-02 - 0.5 0.9 1,2 0.8 Coating Properties ^* Shine 3 four 3 four four Transparency four four 5 5 four Acid resistance (citric acid: 2% solution: 70 ° C, 20 min) four 5 5 5 four Alcohol resistance (ethyl alcohol: 3% solution: 70 ° C, 20 min) 3 four four 3 four Resistance to pasteurization (water: 80 ° C, 30 min.) 5 5 5 5 four Continuity, mA ^** 19.8 2.0 1,5 0.8 8.2

^* - coating properties were measured in points: 1 - unsatisfactory ^** - measured according to GOST R 51756-2001 5 - excellent

The resulting compositions are milky white varnishes with a density of 1.02 ± 0.018 g / cm ³ and a viscosity of 19-20 s (VZ-246 with a nozzle with a diameter of 4 mm at 25 ° C). Varnishes can be applied by airless spraying under high pressure, in bulk, by dipping. Drying mode of coatings until fully cured: 200 ° C for 4 min.

Coatings based on all the obtained varnishes have excellent flexibility (according to the ShG device, GOST 6806-73) and adhesion to an aluminum substrate (lattice notch method, GOST 15140-78). The coatings are resistant in washing solutions and during pasteurization (71 ° C for 100 s), withstand a long (at least 1 year) stay in the environment of low alcohol and non-alcoholic carbonated drinks at an internal pressure of up to 6 atm and a temperature difference of +5 - + 30 ° FROM.

All synthesis recipes considered allow to obtain ready-to-use paintwork material. As can be seen from the above examples, the additional introduction of the melamine-formaldehyde oligomer into the composition provides not only a high continuity of the resulting coatings, but also a higher hydrolysis resistance during storage of the paint composition, which ensures the sedimentation stability and the varnish dispersion composition remains constant for at least two years.

Coatings obtained on the basis of the proposed composition have high physical and mechanical properties not inferior to the properties of coatings obtained by the prototype.

Claims (1)

A water-borne composition for protective coatings, including epoxy oligomers with a molecular weight of 2000-10000 and 200-500, unsaturated monomers: methacrylic acid, methyl methacrylate, styrene, ethyl acrylate, neutralizing agents, organic solvents, benzoyl peroxide and distilled water, characterized in that the composition is additionally contains a curing agent - water-borne melamine-formaldehyde oligomer in the following ratio, wt.%: Epoxy Oligomer with a molecular weight of 2000-10000 5.7-9.0 Unsaturated monomers 10.0-22.0 Benzoyl peroxide 1.2-3.2 Organic solvents 9.0-14.5 Neutralizing agents 1.4-5.0 Distilled water 46.5-69.9 Epoxy Oligomer with a molecular weight of 200-500 1.0-1.2 Melamine formaldehyde oligomer 0.5-1.2