RU2638373C1 - Composition for cathode electrodeposition intended for formation of painted zinc-polymer coatings with increased hardness and water resistance - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: composition for electrodeposition at the cathode is a paint material containing a film former, an epoxyamine adduct modified with blocked isocyanate, transferred to the water-soluble state by the addition of acetic acid, pigment paste, butyl glycol, phenoxypropanol, zinc acetate, and water at a certain ratio of components.

EFFECT: obtaining zinc-polymer coatings with increased hardness and water resistance.

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Description

The invention relates to a new product: an aqueous composition for electrodeposition on the cathode of paint coatings containing zinc, having increased hardness superior to traditional known paint coatings and high water resistance.

The method of coloring by electrodeposition, including at the cathode, which serves as a painted product, is widely used in industry for the production of primers and single-layer coatings [1]. For cathodic electrodeposition, paint and varnish compositions based on oligomeric binder film former polyelectrolytes, in particular epoxyamine adducts of various modifications, are used [2]. Their disadvantage compared to metal plating is low hardness.

Known aqueous paint compositions for cathodic electrodeposition based on a modified epoxyamine adduct containing, to increase hardness, a dispersion of polyphenylene sulfide with additives of silicon carbide and graphite stabilized by OP-10 (nonylphenol). Coatings have a higher hardness than that of a coating without additives. Water resistance does not exceed the initial coating [3].

Known aqueous paint compositions for cathodic electrodeposition based on epoxyamine adducts of various modifications, containing a fluoroplastic dispersion to impart hydrophobicity to the coatings. However, coatings do not have high hardness [4].

The proposed composition for producing coatings by the method of cathodic electrodeposition in terms of hardness and water resistance exceeds both the original paint and varnish material, and the composition of the considered patents. For this, the paint composition in its composition additionally contains a metal salt, in particular zinc. In this case, a joint electrodeposition is carried out at the cathode of the paint material with simultaneous electroreduction of zinc to obtain a metal-polymer precipitate. After subsequent thermosetting, a zinc-polymer coating is formed from the precipitate with a polymer matrix. Similar coatings can be obtained on various conductive products, for example, on car bodies, hardware, instrument housings. In this case, the properties of the resulting coatings will be significantly improved in comparison with the currently used purely polymer coatings based on epoxyamine adducts for cathodic electrodeposition.

The composition is based on the use in a certain ratio of the components of the paint system, which includes:

- water emulsion paint film former with a concentration of 35-36 mass. % by dry residue, which is an epoxyamine adduct modified with blocked toluene diiscyanate with a molecular weight of 1700-2500 and converted to a water-soluble state by the addition of acetic acid and containing the addition of phenoxypropanol and 2-butoxyethanol (butyl glycol);

- pigment paste, which is a dispersion of any pigments used in paints and varnishes, stabilized by the above aqueous emulsion (epoxyamine adduct) with a molecular weight of 1100-1500 with a concentration of 53-56% by dry residue;

- an aqueous solution of zinc acetate with a concentration of 17 mass. % by dry residue (17 g / l).

To obtain a zinc-polymer coating, the composition must be prepared as follows:

Stage 1: to the calculated amount of demineralized water, an aqueous emulsion of a film-forming film former is introduced with stirring and stirring is continued for at least 2 hours;

Stage 2: the calculated amount of zinc acetate solution is added to the emulsion obtained in the first stage and stirring is continued for at least one hour;

Stage 3: the pigment paste is added to the composition obtained in the second stage with stirring and stirring is continued for at least 3 hours.

It turns out an aqueous solution of the composition with the following parameters:

Zinc-polymer coatings are obtained in the electrodeposition bath, in which the painted samples serve as the cathode. The opposite electrode is a stainless steel plate. The surface of the samples to be painted is pre-prepared according to GOST 9.402-2004 "Preparation of metal surfaces for painting." Electrodeposition is carried out in the following mode:

After receiving the coating, the samples are washed with demineralized water and thermoset at 180 ° C for 30 minutes.

The prototype of the new composition is a paint and varnish composition for cathodic electrodeposition based on a modified epoxyamine adduct without zinc acetate.

Table 1 presents the composition of the compositions in the entire range of values, and in Table 2 the properties of the coatings in comparison with the prototype and analogue.

Table 1. The composition in (g / l)

Table 2. Coating Properties

The dispersing ability of compositions 1-3, determined according to GOST 9.413-2007, is at least 15 cm, which allows to obtain a uniform coating thickness on products of complex configuration.

Information sources

1. Krylova I.A. Painting by electrodeposition the eve of the 21-st century // Progress in Organic Coating. 2001. Vol. 42. P. 119-131.

2. Kvasnikov M.Yu., Krylova I.A. // Paintwork materials and their application. 2001. No. 4-6. S. 10, S. 24, S. 26.

3. Patent of Russia No. 2486220.

4. Patent of Russia No. 2222562.

Claims (2)

A composition for producing zinc-polymer coatings with increased hardness and water resistance by cathodic electrodeposition, comprising an epoxyamine adduct modified as a film former, blocked with toluene diisocyanate with a molecular weight of 1700-2500 and converted to a water-soluble state by an additive - acetic acid - and containing phenoxy-propane and butoxyethanol (butyl glycol), a pigment paste, which is a dispersion of any pigment used in paints and varnishes s in an epoxyamine adduct modified with blocked toluene diisocyanate with a molecular weight of 1100-1500, and water, characterized in that it further comprises zinc acetate in the following components (g / l): Epoxyamine Adduct one hundred Pigment paste 28-32 Acetic acid 0.4 2-butoxyethanol (butyl glycol) 3.5-4.1 Phenoxypropanol 4,5-5,1 Zinc Acetate 0.17-0.51 Demineralized water The rest is up to 1 liter