RU2532245C2 - Method of applying polyphenylene sulphide-based coating on metal substrate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of applying polyphenylene sulphide-based coating on a metal substrate is characterised by applying onto the surface of the metal substrate 3 vol % of an aqueous solution of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane by immersion, drying at 120°C for 60 minutes and electrostatic spraying a polyphenylene sulphide-based powder coating. The metal substrate used is made of low-carbon steel, carbon steel or cast iron.

EFFECT: high adhesion of the coating to the metal substrate and protection from underfilm corrosion when integrity of the coating is breached, which improves corrosion and chemical resistance of the polyphenylene sulphide-based coating.

2 cl, 2 dwg, 1 ex

Description

This invention relates to the field of polymer coating technology - improving the operational properties of polymer coatings by increasing the adhesion of the main coating to a metal substrate.

The adhesion of the coating to the substrate is the main factor determining the quality of the coating. The “coating-substrate” bond characterizes the behavior of the protective layer, therefore, when developing coatings, special attention is always paid to the surface quality of parts and the compatibility of dissimilar materials.

When applying any type of coating, special attention is paid to the cleanliness of the surface of the substrate, which in turn determines the level of adhesion of the future coating. This explains the variety of different types of surface cleaning before coating and the almost complete absence of surface modification technologies for specific types of coatings. Research here, as a rule, ends with the development of special coating compositions for specific substrates.

The main objective of the research work carried out within the framework of the topic under discussion is the creation of a universal primer agent for substrates of carbon steels when applying coatings based on polyphenylene sulfide.

The use of silanes, a large group of organosilicon compounds, is common in many industries, including the polymer industry. However, research here is primarily aimed at creating polymer composites, i.e. Using silanes, surface modification of various kinds of fillers of polymeric materials is performed to increase their adhesion to the matrix.

So the group (CH ₃ -Si-) has a stable and strong bond, it is non-polar and is responsible for the reduction of surface energy and hydrophobic effects; the group (-Si-H), on the contrary, is very active, interacts with water and carbon, forming new compounds; the methoxy group is also very active and, reacting with carbon and silicon, forms an easily hydrolyzable group; aminopropyl and vinyl groups also actively interact; the group (-Si-O) is responsible for the bond with metals and mineral compounds.

As the closest in technical essence to the claimed invention, there is a known method of coating metal surfaces from an aqueous composition (RF patent No. 2402648 C2, 10.27.2010), including including silanes. The above method is aimed at increasing the corrosion resistance and the level of adhesion between the metal surface and the varnish.

Another author's work (US20040237890 A1, IPC С23С 16/00, 02/02/2004) is devoted to the development of polyphenylene sulfide-based coatings for oil and gas pipelines using an intermediate primer layer based on various phosphates.

The disadvantages of the above methods include the difficulty of compiling hybrid aqueous solutions containing fluorides and phosphates. And the universality of the methods does not allow to obtain reliably reproducible results for specific types of substrates (steel, aluminum, copper, etc.) and coatings.

The technical result of the invention is the development of a universal method of applying a coating based on polyphenylene sulfide on a metal substrate and combating sub-film corrosion in case of violation of the integrity of the coating, which will increase the corrosion and chemical resistance of the coating.

The technical result in the proposed invention is achieved as follows.

The method of coating a polyphenylene sulfide-based coating on a metal substrate, characterized by applying to the surface of a metal substrate a 3 vol.% Aqueous solution of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane by dipping, drying at a temperature of 120 ° C for 60 minutes and electrostatic powder spraying polyphenylene sulfide based coatings.

As the metal substrate, a substrate of low carbon steel, carbon steel or cast iron is used.

The method is as follows.

A 3 vol.% Aqueous solution of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane is applied to the surface of the metal substrates. A solution of organosilicon compounds is applied to the protected part by dipping. After that, the part is placed in a drying chamber and drying is carried out at 120 ° C for 60 minutes. During this time, water has time to evaporate from the surface of the substrate, and a nanosized layer of organosilicon compound is formed on it. After the intermediate primer layer is obtained, a polyphenylene sulfide base coating is applied to the part. When a coating is formed in the furnace, a stable chemical bond is formed between the polyphenylene sulfide and the metal substrate. The formation of communication is presented in Figure 1.

The possibility of industrial applicability of the proposed method and obtained with its use of polymer coatings based on polyphenylene sulfide is confirmed by the following implementation example.

Example.

As starting materials, we used a 3 vol.% Aqueous solution of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, a polyphenylene sulfide-based powder coating, and steel plates (St08, steel 40).

The solution was applied to the metal substrate by dipping, after which the plate was placed in an oven (120 ° C) for 60 minutes. Immediately after drying, a powder coating was applied to the plate by electrostatic spraying. After forming the coating in the furnace, the plate was subjected to tests to determine the level of adhesion. For a comparative analysis of the test, plates that did not pass the surface modification were tested. Coating adhesion was determined in two ways.

The first is by peeling off according to ISO 4624, ASTM D 4541. It was found that the adhesion level of the coatings on wafers with an intermediate silicon layer is 10-15% higher compared to the coating applied on an untreated metal substrate.

The second - by the method of trellised notch according to GOST 15140-78. Perpendicular cuts were made on the coated plates, after which they were immersed for 72 hours in a boiling 7 wt.% NaCl solution. Inspection of the plates after the test showed that on the modified plate there are no traces of corrosion and destruction of the main coating, and on an unmodified plate there is film-like corrosion and destruction of the main coating (Figure 2).

Claims (2)

1. The method of applying a coating based on polyphenylene sulfide on a metal substrate, characterized by applying to the surface of a metal substrate 3 vol.% Aqueous solution of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane by dipping, drying at a temperature of 120 ° C for 60 minutes and electrostatic powder coating based on polyphenylene sulfide. 2. The method according to claim 1, characterized in that as the metal substrate using a substrate of low carbon steel, carbon steel or cast iron.

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