High-strength anti-erosion self-repairing silicon-based material for underground industrial pipes and preparation method thereof

Abstract

The application belongs to the technical field of coating materials, and particularly relates to a high-strength anti-erosion underground industrial pipeline self-repairing silicon-based material and a preparation method thereof. The high-strength anti-erosion underground industrial pipeline self-repairing silicon-based material comprises organic silicon resin, inorganic nano filler and amino silane coupling agent. The amino silane coupling agent contains 10% to 30% of KH-550 silane coupling agent. The application adopts inner coating and outer coating with the same composition and different amino silane coupling agent contents. The inner coating remains active groups, the outer coating is crosslinked and dense, can isolate the inner coating, and enables the inner coating to keep the active groups remaining for a long time. When the coating is punctured or scratched, the coating can be self-repaired, and can occur polycondensation reaction with the hydroxyl groups (Me-OH) on the surface of the metal pipeline, to form firm covalent bonds (Me-O-Si) again, thereby preventing the defects from being enlarged.

Description

Technical Field

[0001] This invention belongs to the field of coating materials technology, specifically a high-strength, wear-resistant, self-healing silicon-based material for underground industrial pipelines and its preparation method. Background Technology

[0002] Industrial pipelines are subjected to multiple harsh conditions such as soil corrosion and groundwater erosion for a long time, and corrosion and wear of pipelines are one of the important problems they face.

[0003] Currently, protective coatings used for underground pipelines mainly include epoxy resin coatings, polyurethane coatings, and fusion-bonded epoxy powder coatings. These coatings have the following technical defects in practical applications: I. Insufficient internal density of the material: Due to low cross-linking density or incomplete curing, the coating itself contains micropores or localized weak areas. During service, these defects are prone to "skin loss" or "flaking," allowing external corrosive media to penetrate along the defects, causing localized corrosion of the metal beneath the coating, which gradually spreads outwards, resulting in large-area peeling.

[0004] II. Insufficient bonding between the coating and the substrate: The coating itself is dense, but its interfacial bonding strength with the pipe substrate is insufficient. Under the peeling effect of temperature changes and soil stress, micro-gaps are easily generated at the interface. Corrosive media penetrate along the gaps and form "bulges", which then expand and lose their protective function. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-strength, wear-resistant, self-healing silicon-based material for underground industrial pipelines and its preparation method. This solves the problems of insufficient internal compactness of existing coating materials, which easily leads to peeling and flaking, and insufficient bonding between the coating and the substrate, which easily leads to bulging and failure. Moreover, once a small defect occurs in the coating, it cannot repair itself. Under the influence of the external environment, the defect will rapidly expand in a short period of time and lead to large-area failure.

[0006] To achieve the above objectives, the present invention provides the following technical solution: High-strength, wear-resistant, and corrosion-resistant self-healing silicon-based material for underground industrial pipelines, comprising independently mixed components A and B; Component A, by weight, includes the following components: 40-80 parts of organosilicon resin; 10-40 parts of inorganic nanofiller; Additives: 0.5–5 parts; Toluene and butyl acetate are mixed with an appropriate amount of solvent; Component B, by weight, includes the following components: Aminosilane coupling agent, containing 10% to 30% KH-550 silane coupling agent; Component A and Component B are mixed in a first mass ratio to form an inner coating, and mixed in a second mass ratio to form an outer coating; wherein the amount of Component B in the first mass ratio is less than the amount of Component B in the second mass ratio.

[0007] When the aminosilane coupling agent is mixed with component A, it hydrolyzes to generate Si-OH, which can quickly react with the surrounding Si-OH or organosilicon resin end groups to form a three-dimensional network structure. The part in contact with the surface of the metal pipe will undergo a condensation reaction with the hydroxyl groups (Me-OH) on the surface of the metal pipe to form a strong covalent bond (Me-O-Si), thereby achieving chemical anchoring and making the coating and substrate interface tightly bonded.

[0008] It is understandable that aminosilane coupling agents are easily hydrolyzed and react with the hydroxyl groups (Me-OH) on the surface of metal pipes or the terminal hydroxyl groups (Si-OH) of organosilicon resins. When there is an excess, self-condensation occurs to form a dense cross-linked network, and a large number of active groups are consumed, resulting in a dense coating. When there is a deficiency, after chemically bonding with the metal surface to form a strong anchor, the remaining active groups are preserved (there are spatial gaps between the active groups), providing a basis for self-repair after the coating is damaged.

[0009] Component A serves as the film-forming skeleton and wear-resistant reinforcing phase of the coating, providing basic mechanical strength and wear resistance. Component B acts as a crosslinking curing agent, enabling crosslinking and curing of the coating itself and chemical bonding with the pipe substrate. The aminosilane coupling agent has a unique "bifunctional" structure. One end of its hydrolyzable group (-OC2H5) can undergo a condensation reaction with the hydroxyl groups on the surface of the pipe metal substrate to form a strong chemical bond (Fe-O-Si). The other end of its amino group (-NH2) can react chemically with the organosilicon resin in the coating or form a strong hydrogen bond, thereby building a stable "molecular bridge" between the coating and the substrate. In particular, an aminosilane coupling agent containing KH-550 silane coupling agent is selected. Its hydrolysis rate is stable, and with reasonable timing control during the curing stage, it can leave active groups. After the outer coating forms a sealing layer, it can prevent the aminosilane coupling agent from continuing to play its role, maintaining long-term active group residue. When pinhole-like damage occurs later, the residual active groups play a self-repairing role after damage.

[0010] Preferably, the organosilicon resin is one or a mixture of multiple of the following: hydroxyl-terminated polydimethylsiloxane, epoxy-modified organosilicon resin, polysiloxane resin, and methylphenyl silicone resin.

[0011] Preferably, the inorganic nanofiller is one or a mixture of nano-silicon carbide and nano-alumina, and the particle size of the inorganic nanofiller is 10-100nm, such as 20nm, 40nm, 60nm, 90nm, etc.

[0012] Preferably, in the first mass ratio, the mass ratio of component A to component B is 100:(5-9); In the second mass ratio, the mass ratio of component A to component B is 100:(13-15).

[0013] In the first mass ratio, the content of component B is relatively small, and there is an obstacle to the reaction between component A and component B, resulting in insufficient formation of a dense three-dimensional network layer, and the formed layer has residual active groups. In the second mass ratio, the content of component B is relatively large, and the reaction between component A and component B is sufficient, resulting in self-condensation to form a dense cross-linked network, with a large amount of active groups being consumed, and the coating becoming dense.

[0014] For example, in the first mass ratio, the mass ratio of component A to component B is 100:7; in the second mass ratio, the mass ratio of component A to component B is 100:14.

[0015] A method for preparing a high-strength, wear-resistant, and corrosion-resistant self-healing silicon-based material for underground industrial pipelines includes the following steps: S1. Mix 40-80 parts of organosilicon resin, 10-40 parts of inorganic nanofiller, 0.5-5 parts of additives and an appropriate amount of toluene and butyl acetate compound solvent thoroughly, grind to a fineness ≤30μm, filter and discharge to obtain component A; S2. Mix the aminosilane coupling agent containing KH-550 silane coupling agent evenly to obtain component B; The A component obtained in steps S3 and S1 is mixed with the B component obtained in step S2 at the first mass ratio, stirred evenly, and then degassed under vacuum to obtain the inner coating layer. The A component obtained in steps S4 and S1 is mixed with the B component obtained in step S2 at a second mass ratio, stirred evenly, and then cured to obtain the outer coating; and the amount of B component in the first mass ratio is less than the amount of B component in the second mass ratio. S5. Spray the inner coating obtained in step S3 onto the surface of the pipe to form the first coating. Before the first coating is fully cured, spray the outer coating obtained in step S4 onto the surface of the first coating to form the second coating. After both are cured, a composite coating is obtained.

[0016] The first and second coatings have the same composition, and the spraying of the first and second coatings is completed within a certain time. The composite coating formed by spraying has no obvious interface effect, and the two layers are closely distributed.

[0017] Preferably, the stirring in step S3 is carried out in a vacuum-sealed reactor.

[0018] Preferably, the dry film thickness of the first coating is 120-200 μm; the second coating is applied 15-30 minutes after the first coating is applied.

[0019] Preferably, the dry film thickness of the second coating is 90–120 μm.

[0020] The present invention has the following beneficial effects: 1. This invention uses a combination of organosilicon resin and aminosilane coupling agent to form a coating. The aminosilane coupling agent is mixed with component A, and its hydrolysis generates Si-OH, which can quickly react with the surrounding Si-OH or organosilicon resin end groups to form a three-dimensional network structure. The part in contact with the surface of the metal pipe will undergo a condensation reaction with the hydroxyl groups (Me-OH) on the surface of the metal pipe to form a strong covalent bond (Me-O-Si), thereby achieving chemical anchoring and making the coating and substrate interface tightly bonded.

[0021] 2. This invention uses inner and outer coatings with the same composition but different aminosilane coupling agent contents. The inner coating has a lower aminosilane coupling agent content, resulting in physical spatial barriers to the crosslinking reaction and insufficient formation of a dense three-dimensional network layer. The resulting layer has residual active groups. The outer coating has an excessive aminosilane coupling agent content, which undergoes self-condensation to form a dense crosslinked network. A large number of active groups are consumed, resulting in a dense coating that can isolate the inner coating. This allows the inner coating to retain residual active groups. When subsequent needle punctures or scratches occur, the coating can self-repair and undergo a condensation reaction with the hydroxyl groups (Me-OH) on the surface of the metal pipe to form strong covalent bonds (Me-O-Si) again, thus hindering the expansion of defects.

[0022] 3. The aminosilane coupling agent used in this invention contains 10%–30% KH-550 silane coupling agent. KH-550 silane coupling agent, on the one hand, solves the problem of insufficient interfacial bonding and easy blistering between the coating and the substrate by forming strong chemical bonds with the metal substrate through its hydrolyzable ethoxy groups; on the other hand, it retains a large number of unreacted active groups in the undercured inner coating, providing a material basis for the formation of a denser repair layer after the coating is damaged and exposed to air. Experiments show that when the KH-550 content is 20%, the coating self-repair efficiency reaches 85%, and the needle-piercing corrosion area is only 0.56 mm², significantly better than the comparative example without KH-550. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 High-strength, wear-resistant, and corrosion-resistant self-healing silicon-based material for underground industrial pipelines, comprising independently mixed components A and B; Component A, by weight, includes the following components: 70 parts epoxy-modified silicone resin, 33 parts nano alumina (particle size 10-100nm), 1 part wetting and dispersing agent, 1 part leveling agent, 1 part defoamer (wetting and dispersing agent, leveling agent, and defoamer are collectively referred to as additives), and 100 parts xylene and butyl acetate compound solvent.

[0025] Component B, by weight, includes the following components: aminosilane coupling agent (KH-792 silane coupling agent, KH-550 silane coupling agent), wherein the aminosilane coupling agent contains 10% KH-550 silane coupling agent.

[0026] Example 2 High-strength, wear-resistant, and corrosion-resistant self-healing silicon-based material for underground industrial pipelines, comprising independently mixed components A and B; Component A, by weight, includes the following components: 70 parts epoxy-modified silicone resin, 33 parts nano alumina (particle size 10-100nm), 1 part wetting and dispersing agent, 1 part leveling agent, 1 part defoamer (wetting and dispersing agent, leveling agent, and defoamer are collectively referred to as additives), and 100 parts xylene and butyl acetate compound solvent.

[0027] Component B, by weight, includes the following components: aminosilane coupling agent (KH-792 silane coupling agent, KH-550 silane coupling agent), wherein the aminosilane coupling agent contains 20% KH-550 silane coupling agent.

[0028] Example 3 High-strength, wear-resistant, and corrosion-resistant self-healing silicon-based material for underground industrial pipelines, comprising independently mixed components A and B; Component A, by weight, includes the following components: 70 parts epoxy-modified silicone resin, 33 parts nano alumina (particle size 10-100nm), 1 part wetting and dispersing agent, 1 part leveling agent, 1 part defoamer (wetting and dispersing agent, leveling agent, and defoamer are collectively referred to as additives), and 100 parts xylene and butyl acetate compound solvent.

[0029] Component B, by weight, includes the following components: aminosilane coupling agent (KH-792 silane coupling agent, KH-550 silane coupling agent), wherein the aminosilane coupling agent contains 30% KH-550 silane coupling agent.

[0030] Example 4 A method for preparing a high-strength, wear-resistant, and corrosion-resistant self-healing silicon-based material for underground industrial pipelines includes the following steps: S1. Thoroughly mix the organosilicon resin, inorganic nanofiller, additives and appropriate amount of solvent, grind to a fineness ≤30μm, filter and discharge to obtain component A.

[0031] S2. Mix the aminosilane coupling agent evenly to obtain component B.

[0032] The A component obtained in steps S3 and S1 is mixed with the B component obtained in step S2 at a ratio of 100:6, stirred evenly, and then degassed under vacuum to obtain the inner coating layer.

[0033] The A component obtained in steps S4 and S1 is mixed with the B component obtained in step S2 at a ratio of 100:14, stirred evenly, and cured for more than 30 minutes to obtain the outer coating.

[0034] S5. Spray the inner coating obtained in step S3 onto the pipe surface to form the first coating. Before the first coating is fully cured, spray the outer coating obtained in step S4 onto the surface of the first coating to form the second coating. After both coatings are cured, a composite coating is obtained. The dry film thickness of the first coating is 120-200 μm. The second coating is applied 15-30 minutes after the first coating is applied, and the dry film thickness of the second coating is 90-120 μm.

[0035] Comparative Example 1 Silicon-based materials, comprising independently mixed components A and B; Component A, by weight, includes the following components: 70 parts epoxy-modified silicone resin, 33 parts nano alumina (particle size 10-100nm), 1 part wetting and dispersing agent, 1 part leveling agent, 1 part defoamer (wetting and dispersing agent, leveling agent, and defoamer are collectively referred to as additives), and 100 parts xylene and butyl acetate compound solvent.

[0036] Component B, by weight, includes the following components: aminosilane coupling agent (KH-792 silane coupling agent).

[0037] Based on the independently mixed components A and B in Examples 1, 2, 3, and 1 Comparative Example, and using the preparation method of high-strength wear-resistant and corrosion-resistant self-healing silicon-based material for underground industrial pipelines in Example 4, the following test substrates (plates) were obtained: SQ1: Example 1 + Example 4 (method), SQ2: Example 2 + Example 4 (method), SQ3: Example 3 + Example 4 (method), SQ4: Comparative Example 1 + Example 4 (method). After being placed in the dark for 15 days, the test results are shown in Table 1.

[0038] Needle penetration corrosion test: A 1mm diameter steel needle was used to vertically penetrate the coating to the substrate (board). Three needle penetrations were made on each sample (distributed in a triangle with a spacing of ≥20mm). The sample was then placed in a neutral salt spray chamber (GB / T1771-2007) for 50 hours. After removal, the surface rust was removed, and the average corrosion area (mm²) around each needle penetration point was calculated using ImageJ software. The average value of the three penetrations was taken, and the data is shown in Table 1 below. Referring to GB / T 1771-2007 "Determination of Resistance to Neutral Salt Spray of Paints and Varnishes" and ASTM D1654, a scratcher was used to scratch the surface of the test substrate (board) down to the substrate, forming a single straight scratch with a length of 50 mm. The scratched test substrate (board) was placed in a neutral salt spray test chamber under the following conditions: NaCl solution concentration 5%, temperature 35±2℃, continuous spraying for 50 hours. After the test, the sample was rinsed with clean water, and the corrosion spread width (maximum distance on one side from the edge of the scratch to the farthest corrosion point) was measured along the vertical direction of the scratch using a stereomicroscope (magnification 20×). Measurements were taken at 10 mm intervals, for a total of 5 points, and the arithmetic mean was taken, accurate to 0.01 mm.

[0039] Table 1

[0040] It can be seen that the optimal dosage of KH-550 is 20% of the total amount of component B (i.e., Example 2). Under this condition, the coating has high initial adhesion, and at the same time, the needle puncture corrosion area is the smallest (0.56 mm²) and the scratch expansion width is the narrowest (0.54 mm), achieving the functions of high adhesion and high self-healing.

[0041] When the KH-550 content is too low (10%), although it is better than the comparative example without KH-550, the overall performance may still have room for improvement due to the limited reserve of active groups. When the KH-550 content is too high (30%), not only does it fail to further improve the performance, but the excessive cross-linking leads to the premature consumption of active groups in the coating, and some performance is even worse than the 10% content scheme.

[0042] The above comparison fully demonstrates that by controlling the mass fraction of KH-550 in component B to be between 10% and 30% (especially 20% is optimal), and by combining it with a homogeneous but heterogeneous double-layer structure of "low B in the inner layer and high B in the outer layer", the present invention has successfully solved the technical problems of existing underground pipeline coatings such as "sparse peeling, bulging, difficulty in long-term preservation of activity, and easy expansion of failure after damage".

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines, characterized in that... Includes independently mixed components A and B; Component A, by weight, includes the following components: 40-80 parts of organosilicon resin; 10-40 parts of inorganic nanofiller; Additives: 0.5–5 parts; Toluene and butyl acetate are mixed with an appropriate amount of solvent; Component B, by weight, includes the following components: Aminosilane coupling agent, containing 10% to 30% KH-550 silane coupling agent; Component A and Component B are mixed in a first mass ratio to form an inner coating, and mixed in a second mass ratio to form an outer coating; wherein the amount of Component B in the first mass ratio is less than the amount of Component B in the second mass ratio.

2. The high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines according to claim 1, characterized in that, The organosilicon resin is one or a mixture of multiple of the following: hydroxyl-terminated polydimethylsiloxane, epoxy-modified organosilicon resin, polysiloxane resin, and methylphenyl silicone resin.

3. The high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines according to claim 1, characterized in that, The inorganic nanofiller is one or a mixture of nano-silicon carbide and nano-alumina, and the particle size of the inorganic nanofiller is 10-100 nm.

4. The high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines according to claim 1, characterized in that, In the first mass ratio, the mass ratio of component A to component B is 100:(5-9); In the second mass ratio, the mass ratio of component A to component B is 100:(13-15).

5. A method for preparing the high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Mix 40-80 parts of organosilicon resin, 10-40 parts of inorganic nanofiller, 0.5-5 parts of additives and an appropriate amount of toluene and butyl acetate compound solvent thoroughly, grind to a fineness ≤30μm, filter and discharge to obtain component A; S2. Mix the aminosilane coupling agent containing KH-550 silane coupling agent evenly to obtain component B; The A component obtained in steps S3 and S1 is mixed with the B component obtained in step S2 at the first mass ratio, stirred evenly, and then degassed under vacuum to obtain the inner coating layer. The A component obtained in steps S4 and S1 is mixed with the B component obtained in step S2 at a second mass ratio, stirred evenly, and then cured to obtain the outer coating; and the amount of B component in the first mass ratio is less than the amount of B component in the second mass ratio. S5. Spray the inner coating obtained in step S3 onto the surface of the pipe to form the first coating. Before the first coating is fully cured, spray the outer coating obtained in step S4 onto the surface of the first coating to form the second coating. After both are cured, a composite coating is obtained.

6. The preparation method of the high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines according to claim 5, characterized in that, The stirring in step S3 is carried out in a vacuum-sealed reactor.

7. The preparation method of the high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines according to claim 5, characterized in that, The dry film thickness of the first coating is 120-200 μm; the second coating is applied 15-30 minutes after the first coating is applied.

8. The preparation method of the high-strength, wear-resistant, corrosion-resistant self-healing silicon-based material for underground industrial pipelines according to claim 7, characterized in that, The dry film thickness of the second coating is 90–120 μm.

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