PL237202B1 - Corrosion protective agent - Google Patents

Description

Description of the invention

The subject of the invention is an anti-corrosion protective agent containing modified polysiloxanes.

Until recently, corrosion protection was based mainly on the introduction of metals and coatings - heavy metals - into the treatment, which were inhibitors of the corrosion process. Currently, chromate coatings are withdrawn from use due to carcinogenicity and environmental toxicity. New environmentally safe and renewable sources of corrosion inhibitors are being sought. One of the groups of safe corrosion inhibitors are polysiloxanes with reactive functional groups.

Polysiloxanes are an interesting group of inorganic polymers due to their physicochemical and application properties resulting from their unique chemical structure. They are characterized by stability of properties regardless of temperature, high thermal and oxidation resistance. The ease of functionalization and modification with various functional groups is also important. Epoxy-functional polysiloxanes due to their high reactivity in the processes of cross-linking initiated by UV radiation or in the presence of nucleophilic factors under the influence of thermal or chemical initiation, e.g. cross-linking with amines. Due to the aforementioned properties, epoxy polysiloxane derivatives can be successfully used as substrates for the synthesis of new derivatives and as components of hybrid materials based on epoxy resins.

Epoxy resins enjoy wide application and research interest due to their desired performance properties (chemical, mechanical and oxidation resistance [Tsuchida K., Bell JPJ Appl. Polym. Sci. 2001, 79, 1359-1370]. They can be hardened with amines. or carboxylic acid anhydrides over a wide temperature range [Luo X., Zheng S., MaD. Chin. J. Polym. Sci. 1995, 13, 144-153],

For years, work has been carried out to improve the properties of epoxy binders in the direction of reducing VOC, improving the resistance of coatings to UV radiation and to aggressive media, such as concentrated acids and chlorinated hydrocarbons. Improvement of these properties can be obtained by using epoxy-functional polysiloxanes [M. Zubielewicz, W. Gnot, Protection against corrosion, 4 (2005) 98-100],

Sun used a polysiloxane containing aminoethylamino groups cross-linked with an epoxy cross-linking agent to produce coatings on the steel surface [X. Sun et al., J. Coat. Technol. Res., (2017) DOI 10: 1007 / s11998-017-9918-5], The produced coatings interact with the metal surface on the basis of physical interactions, their adhesion depends on the nature of the coated surface. Coatings based on the epoxy-polysiloxane composite system show greater flexibility compared to analogous stand-alone systems based on epoxy resins. Sun used complex blends of polysiloxane and at least seven other ingredients. In addition, it was necessary to prepare the mixtures under an inert gas atmosphere and in some cases it was necessary to add a solvent to allow better mixing of the ingredients and to reduce the viscosity of the mixtures.

The aim of the invention was to develop an anti-corrosion agent that creates durable and flexible coatings with increased hydrophobicity.

The subject of the invention is an anti-corrosion protective agent consisting of two components, the first of which contains modified polysiloxanes of the general formula 1,

(1) in which:

R ¹ is a substituent containing an epoxy group as described by formulas 2, 3 and 4, where n is an integer from 1 to 8,

PL 237 202 Β1

4c </ ° - + 0 ^ 0- ^ 0 ° (2) (3)

(4)

R ² represents an alkyl group containing from 3 to 20 carbon atoms, x takes a value from 20 to 200, and y and z are from 1 to 50, the distribution of functional groups in the polysiloxane of formula 1 is statistical, and may also contain epoxy resins, as well as it may contain the epoxy functional disiloxane of formula 5

R ¹ . LO J _ή

Si Si R ¹ (5) wherein R ¹ has the meaning described above.

The second component contains an amine hardener selected from the group of: primary and secondary diamines, aliphatic or aromatic polyamines.

In case component A also contains epoxy resins, the content of the polysiloxane of the formula I is from 20% to 99%, preferably 50-90%.

Both components must be mixed immediately before application.

In cases where the viscosity of component A is high, the addition of disiloxane of formula V is used to facilitate the mixing of components A and B before the application of the agent.

The amount of component B added to component A is determined on the basis of the total epoxy number of the compounds contained in component A, so that for each epoxy group there will be 0.8-1.2 active hydrogen from the NH2 or NH group, preferably 1 hydrogen atom.

Modified polysiloxane of general formula I is obtained by hydrosilylation of two different olefins (one is an alkene, the other is an unsaturated compound containing epoxy groups, e.g. allyl glycidyl ether) with a polyhydrogen siloxane in the presence of platinum and rhodium catalysts, according to the publication [H. Maciejewski et al., Reactive and Functional Polymers 83 (2014) 144-154],

The mixture of polysiloxane with epoxy resin and / or disiloxane is obtained by thoroughly mixing specific amounts by weight of individual components in accordance with the description of the mixture.

The use of disiloxane of the formula V makes it possible to resign from the use of organic solvents (reduction of VOC emissions) and due to the presence of epoxy groups, disiloxane is incorporated into the cross-linked protective coating. The lack of solvent has a positive effect on the curing of the coating, the coating does not require conditioning to remove the solvent, and the coating does not form bubbles that may arise from solvent evaporation from partially cross-linked coatings.

The agent can be used to protect all surfaces of metals and / or their alloys, such as steel, aluminum, copper, zinc in particular.

The agent according to the invention can be used to create a cross-linked protective coating on the surface of metals or their alloys.

PL 237 202 B1

Before commencing the application of the agent, the metal surface is cleaned to remove any dirt, dust and previous corrosion products using commonly known cleaning methods. It is advantageous to additionally immerse the cleaned metal surface in an aqueous KOH solution in order to de-block the hydroxyl groups present on the metal surface.

The anticorrosive agent according to the invention can be applied to metal surfaces in any way, e.g. by dipping, spraying, coating, etc. The choice of the method depends on the viscosity of the agent, in the case of high viscosity of the agent, it is preferable to apply it by dipping or coating. The application process is preferably carried out at room temperature. The resulting coatings are then dried at room temperature or elevated temperature to cure the coating.

The agent of the invention contains polysiloxanes functionalized with two or more functional groups. The solutions known so far have not used polysiloxanes to which more than one functional group has been introduced.

Corrosion tests of the metal tiles obtained in the examples were carried out in the SC 450 salt chamber by Weiss Technik by spraying a neutral brine solution (Neutral salt spray NSS) in accordance with the PN-EN ISO 9227: 2017 standard. The test time was 168 hours. Four plates each coated with the agent were placed in the chamber. The visual inspection of the steel surfaces exposed to the salt spray was performed every 24 hours. The table shows the average time after which the first signs of corrosion appeared in the form of point white corrosion products.

The following examples illustrate the invention:

P r z v k ł a d I

A. Preparation of the measure

To 20 g of component A, which includes only polysiloxane containing 17 mole% of octyl groups and glycidoxypropyl groups (x = 50, y and z = 12) with an epoxy number equal to 0.15, 1.1 g of component B containing the amine hardener Z-1 were added . The whole was mixed for 15 minutes immediately before being applied to the surface of the steel plate.

B. Implementation of coatings

The 304 stainless steel plates were washed sequentially with acetone and a 10% aqueous KOH solution to purify and deblock the hydroxyl groups on the steel surface. On the plates of 304 stainless steel prepared in this way, the agent was applied according to point A in the form of a thin film. The plates with the mixture applied were left for 24 hours at room temperature to cross-link the coating.

The plates with the preservative were tested in a salt spray chamber. The results are given in Table 1.

P r z v k ł a d II

To 20 g of component A, which includes 10 g of polysiloxane, each containing 17 mol% of octyl and glycidoxypropyl groups (x = 50, y and z = 12), and 10 g of Epidian 6 epoxy resin, 6.5 g of component B containing the amine hardener IDA were added. The setup was mixed and applied to 304 stainless steel panels prepared according to the procedure given in Example 1. The plaques with the mixture were left for 24 hours at room temperature to cross-link the coating.

The plates with the preservative were tested in a salt spray chamber. The results are given in Table 1.

P r z v k ł a d III

To 40 g of component A, which includes 20 g of polysiloxane, each containing 17 mol% of octyl and glycidoxypropyl groups (x = 50, y and z = 12), and 20 g of disiloxane, 3.7 g of component B containing the Z-1 hardener were added. The mixture was stirred for 15 minutes and applied to stainless steel plates prepared according to the procedure given in Example 1. The plates with the mixture applied were left for 24 hours at room temperature to cross-link the coating.

The plates with the preservative were tested in a salt spray chamber. The results are given in Table 1.

P r z v k ł a d IV

1.1 g of component B containing the hardener Z-1 was added to 10 g of component A, which consists only of polysiloxane, each containing 17 mole% of octyl groups and glycidoxypropyl groups (x = 50, y and z = 12) with an epoxy number equal to 0.15. The mixture was stirred for 15 minutes

PL 237 202 Β1 and applied to 5083 aluminum alloy plaques prepared according to the procedure given in Example 1. Plaques coated with the mixture were left for 24 hours at room temperature to cross-link the coating.

The plates with the preservative were tested in a salt spray chamber. The results are given in Table 1.

Example V

To 20 g of component A, which includes 10 g of polysiloxane with 17 mol% of octyl and glycidoxypropyl groups (x = 50, y and z = 12), and 10 g of Epidian 6 epoxy resin, 6.5 g of component B containing the amine hardener IDA were added. The system was mixed and applied to 5083 aluminum alloy plates prepared according to the procedure given in Example 1. The plates with the mixture applied were left for 24 hours at room temperature to cross-link the coating.

The plates with the preservative were tested in a salt spray chamber. The results are given in Table 1.

Table 1 - test results in a salt spray chamber

Sample name Mean time to the appearance of corrosion signs [h] 304 stainless steel control sample 72 Example I. 108 Example II 120 Example III 105 5083 aluminum control sample 24 Example IV 90 Example V 96

The data in Table 1 show the results of the observation of the tiles in accelerated tests in a salt spray chamber simulating sea conditions. The obtained results indicate an improvement in the corrosion resistance of steel and aluminum plates coated with the agent according to the invention compared to the uncoated control samples.

Claims (3)

1. Anti-corrosion protection agent consisting of two components, characterized in that the first component contains modified polysiloxanes of the general formula 1, Me ₃ SiMe ₃ (i) where: - R ¹ is a substituent containing an epoxy group described by formulas 2, 3 and 4, where n is an integer from 1 to 8, PL 237 202 Β1 -4ch ^ (2) (3) (4) - R ² represents an alkyl group having from 3 to 20 carbon atoms - x takes a value from 20 to 200 and y and z are from 1 to 50, the distribution of functional groups in the polysiloxane of formula I is statistical; and in addition it may contain epoxy resins as well as may contain epoxy functional dosilixane of formula 5 in which R ¹ has the meaning described above; and the second component contains an amine hardener selected from the group of primary and secondary diamines, aliphatic or aromatic polyamines. 2. The agent according to claim. 2. The process of claim 1, wherein the first component comprises epoxy resins and the content of the polysiloxane of the formula I is from 20% to 99%, preferably 50-90%. 3. The agent according to claim. A process as claimed in claim 1 or 2, characterized in that the first component comprises an epoxy-functional dosilixane of the formula 5.