PL237201B1 - 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 Currently, chromate coatings are withdrawn from use due to carcinogenicity and environmental toxicity.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.

There are also examples of the use of modified polysiloxanes for the production of protective coatings. Polysiloxanes containing reactive functional groups that can form cross-linked three-dimensional structures are used. 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 / s 11998-017-9918-5], The produced coatings interact with the metal surface on the basis of physical interactions, their adhesion depends on the nature of the coated surface.

Singh-Beemat used polymethylhydridosiloxane in polymer coatings with polyurea with the addition of montmorillonite to create protective coatings on the aluminum surface. The obtained coatings successfully limited the occurrence of the corrosion process [J. Singh-Beemat, J. O. Iroh, Polymer Engineering and Science (2012) 2611-2620],

Gao received protective coatings based on the polyurethane / polysiloxane system with the addition of titanium oxide. The polysiloxane fragment was obtained by the tetraethoxysilane sol-gel process. The obtained coatings effectively protected the aluminum surface against corrosion [T. Gao et al., J. Appl. Polym. Sci. (2016) DOI: 10.1002 / app.42947], As with Sun's coatings, epoxy ester / polyurea / polysiloxane and polyurethane / polysiloxane hybrid coatings are examples of physical interaction coatings that do not involve direct chemical bonding between metal and shell atoms.

The aim of the invention was to develop an anti-corrosion agent permanently bonded to the metal surface by chemical bonds.

The subject of the invention is an anti-corrosion protective agent containing modified polysiloxanes of the general formula 1,

Me ₃ Si - O-Si-OSi-O-Si-O-SiMe ₃ xL r ² Jz r

Si (OR ¹ ) ₃ (I) where:

R ¹ is an alkyl group having up to 1 to 4 carbon atoms, preferably a methyl or ethyl group, the R ¹ groups may be equal or different, and R ² is an alkyl group containing up to 3 to 20 carbon atoms, x is 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, in the form of a solution of polysiloxane or a mixture thereof in alcohols or mixtures thereof in a concentration of 1 to 50% of polysicoxane or a mixture thereof.

The use of methyl and ethyl alcohol is preferred. Preferably, solutions with a concentration of up to 5 to 30% have properties.

The agent is obtained by mixing the polysiloxane of formula 1 with the solvent.

The anti-corrosion agent according to the invention can be applied to metal surfaces in any way, e.g. by dipping, spraying, coating, etc.

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 being the subject of the invention can be used to create a protective coating on the surface of metals or their alloys, chemically bonded to the surface as a result of the reaction.

The hydrolytic condensation of the hydroxyl groups on the metal surface with the alkoxy groups of the silyl substituents found in the modified polysiloxane of general formula 1.

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 agent can be applied using available methods of applying liquid protective agents: painting, spraying, dipping, sonication. The application process is preferably carried out at room temperature. Then, the obtained coatings are dried at room or elevated temperature, during drying, water is removed and the alkoxysilyl groups Si (OR1) 3 of the compound of formula 1 are reacted. During drying, the metal elements covered with a protective coating should be in an upright position.

The agent according to the invention, thanks to the presence of alkoxysilyl groups (-Si (OR1) 3 groups in formula 1, can chemically bind to the surface of most metals (metals containing hydroxyl groups on the surface). Previously known solutions did not use polysiloxanes to which more than one functional group was added.

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:

The polysiloxanes used in the examples have a random / random distribution of mers in the polymer chains.

P r z v k ł a d I

A. Preparation of the measure

A 30% solution of polysiloxane in ethanol was prepared with the addition of tetraethoxysilane by mixing 30 g of polysiloxane containing 17 mole% octyl and trimethoxysilylethyl groups (x = 50, y and z = 12), 15 g of tetraethoxysilane and 55 mL of ethanol. The system was acidified with acetic acid to pH = 2. The solution was stirred for 4 hours at room temperature.

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. The steel plates prepared in this way were immersed in the vessel containing the agent obtained according to point A. The vessel was then placed in an ultrasonic cleaner (Bandelin Sonorex RK 255 H) for 15 minutes. After the deposition process, the steel plates with the polysiloxane coatings applied were dried in a vertical position at 80 ° C for one hour.

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

A 30% solution of polysiloxane in ethanol was prepared with the addition of tetraethoxysilane by mixing 30 g of polysiloxane containing 17 mole% octyl and trimethoxysilylethyl groups (x = 50, y and z = 12), 15 g of tetraethoxysilane and 55 mL of ethanol. The system was acidified with acetic acid to pH = 2. The solution was stirred for 4 hours at room temperature. The 304 stainless steel plates prepared according to the procedure given in Example 1 were then immersed in a vessel containing a 30% solution of polysiloxane in ethanol for 5 minutes. After removal of the agent from the solution, the plates were placed upright on an absorbent material (paper towel) to remove excess surface runoff and then left in the air for a period of 3 minutes. The process of dipping in solution and drying in air was repeated three times. The tiles were then dried in an upright position at 80 ° C for one hour.

PL 237 201 Β1

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

Example III

A 30% solution of polysiloxane in ethanol was prepared with the addition of tetraethoxysilane by mixing 30 g of polysiloxane containing 7 mole% octyl groups and 27 mole% trimethoxysilylethyl groups (x = 50, y = 20 and z = 5), 15 g tetraethoxysilane and 55 mL of ethanol. The system was acidified with acetic acid to pH = 2. The solution was stirred for 6 hours at room temperature. The 304 stainless steel plates prepared according to the procedure given in Example 1 were then immersed in a vessel containing a 30% solution of polysiloxane in ethanol for 5 minutes. After removal of the agent from the solution, the plates were placed upright on an absorbent material (paper towel) to remove excess surface run-off and then left in the air for a period of 3 minutes. The process of dipping in solution and air drying was repeated three times. The tiles were then dried in an upright position at 80 ° C for one hour.

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

Example IV

A 30% solution of polysiloxane in ethanol was prepared with the addition of tetraethoxysilane by mixing 30 g of polysiloxane containing 17 mole% octyl and trimethoxysilylethyl groups (x = 50, y and z = 12), 15 g of tetraethoxysilane and 55 mL of ethanol. The system was acidified with acetic acid to pH = 2. The solution was stirred for 4 hours at room temperature. Then the 5083 aluminum alloy plates, prepared according to the procedure given in Example 1, were immersed in a vessel containing a 30% solution of polysiloxane in ethanol for 5 minutes. After removal of the agent from the solution, the plates were placed upright on an absorbent material (paper towel) to remove excess surface runoff and then left in the air for a period of 3 minutes. The process of dipping in solution and drying in air was repeated three times. The tiles were then dried in an upright position at 80 ° C for one hour.

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

Table I - test results in the salt spray chamber

Sample name Mean time to the appearance of corrosion signs [h] 304 stainless steel control sample 72 Example I. 138 Example II 135 Example III 126 5083 aluminum control sample 24 Example IV 108

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 containing polysiloxanes, characterized in that it contains modified polysiloxanes of the general formula 1, Me ₃ Si — O-Si — OSi-O-Si- O-SiMe ₃ r Si (OR ¹ ) ₃ xL r ² Jz (1) where: - R ¹ is an alkyl group having up to 1 to 4 carbon atoms, preferably a methyl or ethyl group, the R ¹ groups may be equal or different, - R2 is an alkyl group with up to 3 to 20 carbon atoms - x takes a value from 20 to 200, and y and z take a value from 1 to 50, the distribution of functional groups in the polysiloxane of formula 1 is statistical or their mixture and alcohols, the concentration of polysiloxanes being from 1 to 50%. 2. The agent according to claim. The process of claim 1, wherein the concentration of the polysiloxanes is 5 to 30%. 3. The agent according to claim. The process of claim 1 or 2, characterized in that it contains methyl or ethyl alcohol or a mixture thereof.