A fiber-reinforced alcohol-soluble inorganic zinc-rich primer and its preparation method

Abstract

This invention provides a fiber-reinforced, alcohol-soluble, inorganic zinc-rich primer and its preparation method. The primer is composed of polyethyl silicate, deionized water, anhydrous ethanol, mixed acid, hydrolysis modifier, organosilicon compound, zinc powder, filler, isopropanol, polyvinyl butyral resin, organobentonite, and glass fiber. Through organosilane modification, this invention optimizes the surface energy of the main agent solution, improving the wettability of the primer on steel substrates; it also provides additional chemical bonding anchoring sites, strengthening the interfacial bonding strength between the inorganic crosslinking network and the steel substrate.

Description

Technical Field

[0001] This invention belongs to the field of industrial coatings technology, specifically relating to a fiber-reinforced alcohol-soluble inorganic zinc-rich primer and its preparation method. Background Technology

[0002] Alcohol-soluble inorganic zinc-rich primer is a two-component heavy-duty anti-corrosion primer with ethyl silicate hydrolysate as the inorganic film-forming base, zinc powder as the anti-rust pigment, and alcohol as the dispersion medium. It boasts advantages such as long anti-corrosion life, rapid drying, high construction efficiency, resistance to 400℃ high temperatures, and weldability and cutting capability. It is widely used as the first coat for large steel structures such as ships, pipelines, storage tanks, and bridges. The anti-corrosion mechanism of alcohol-soluble inorganic zinc-rich primer mainly lies in the fact that metallic zinc has a more negative electrode potential than iron, making it more prone to losing electrons and thus providing sacrificial anodic cathodic protection to the steel substrate. Furthermore, the zinc salts and chelates formed after the zinc corrosion reaction are chemically stable and can fill the pores of the paint film, forming a dense barrier that prevents corrosive media from penetrating and protects the steel substrate from corrosion. However, traditional alcohol-soluble inorganic zinc-rich primers have the problem of low construction tolerance. Improper construction operations can easily lead to various coating defects. The main construction pain points are as follows: (1) High requirements for substrate treatment: steel usually needs to be sprayed to Sa2.5 or higher grade, otherwise the coating is very easy to peel off; (2) Strict control of film thickness: the film thickness must be strictly controlled at 80 micrometers or lower (especially in areas with multiple sprayings such as the inside corners of equipment), otherwise the coating may crack due to shrinkage stress generated during curing; (3) Strict requirements for curing environment: the humidity at the curing site must be kept above 50% (usually water spraying is required), otherwise the coating will not be fully cured.

[0003] Therefore, this invention provides a modified alcohol-soluble inorganic zinc-rich primer and its preparation method, aiming to improve the curing stability, adhesion and thick film crack resistance of inorganic coatings through the synergistic effect of polymerization activity regulation, silane modification and glass fiber reinforcement, and significantly improve the application tolerance of inorganic zinc-rich primer. Summary of the Invention

[0004] The purpose of this invention is to provide a fiber-reinforced alcohol-soluble inorganic zinc-rich primer and its preparation method. This inorganic zinc-rich primer consists of component A and component B, wherein component A is the main agent of the alcohol-soluble inorganic zinc-rich primer, which plays a film-forming role in the inorganic zinc-rich primer; component B is an alcohol-soluble inorganic zinc-rich primer paste, which plays a corrosion-preventing role in the inorganic zinc-rich primer.

[0005] A fiber-reinforced, alcohol-soluble, inorganic zinc-rich primer is composed of component A and component B in a mass ratio of 1:(3-8).

[0006] Component A (main agent) consists of the following ingredients by weight:

[0007] 60-70 parts of polyethyl silicate

[0008] 12-18 parts deionized water

[0009] 9-16 parts of anhydrous ethanol

[0010] 1-3 parts mixed acid

[0011] Hydrolysis regulator 1.0-2.5 parts

[0012] 0.6-2.0 parts of organosilicon compound;

[0013] Component B (paste) consists of the following ingredients by weight:

[0014] 60-70 parts zinc powder

[0015] 10-18 parts of filler

[0016] Isopropyl alcohol 14.5-18.5 parts

[0017] 1-3 parts of polyvinyl butyral resin

[0018] 0.5-2.5 parts organic bentonite

[0019] 0.5-1.5 parts glass fiber;

[0020] The organosilicon compound is a mixture of methyltriethoxysilane and dimethyldiethoxysilane.

[0021] In the aforementioned primer, the polyethyl silicate is polyethyl silicate-40.

[0022] In the aforementioned primer, the mixed acid is a mixture of hydrochloric acid, lactic acid, and glacial acetic acid, with a mass ratio of (0.3~2):(0.5~2):(0.5~2); the hydrolysis regulator is a mixture of glacial acetic acid and sodium acetate, with a mass ratio of (2~3):1; and the mass ratio of methyltriethoxysilane and dimethyldiethoxysilane is (1.5~3):1.

[0023] In the aforementioned primer, the zinc powder is spherical 800-mesh zinc powder from Jiangsu Kecheng, the polyvinyl butyral resin is purchased from Guangdong Yuemei Chemical (copper cup viscosity 10s), and the organic bentonite is Zhejiang Fenghong BS-1C organic bentonite.

[0024] In the above primer, the filler is a mixture of silica powder, wet sericite powder and 1250 mesh talc powder, with a mass ratio of (4~8): (3~6): (4~6).

[0025] In the aforementioned primer, the glass fiber is alkali-free glass fiber with a single strand diameter of 10±5 μm and a length of 300±50 μm.

[0026] The preparation method of components A and B in the above primer includes the following steps:

[0027] S1: Add anhydrous ethanol to the reaction vessel, heat in a water bath to 30-40℃, add polyethyl silicate, and stir under controlled temperature until uniformly mixed; while stirring, first add methyltriethoxysilane, mix well, then add deionized water and mixed acid dropwise, completing the addition within 1-2 hours; after sampling and testing the gel time to 15-35 seconds, raise the temperature to 50℃, then add dimethyldiethoxysilane and stir until uniformly mixed; slowly add hydrolysis regulator to the vessel, completing the addition within 0.5-1.5 hours, then maintain the temperature for reaction until the gel time reaches 95-130 seconds, cool, and filter to obtain component A;

[0028] S2: According to the formula, add polyvinyl butyral resin and isopropanol into the material tank, stir at room temperature to completely dissolve, and obtain polyvinyl butyral resin liquid; after the glass fiber and zinc powder are dry mixed evenly, add them to the polyvinyl butyral resin liquid in batches and mix evenly; then add filler and organic bentonite, disperse at high speed and filter to obtain component B.

[0029] S3: Mix components A and B evenly to obtain fiber-reinforced inorganic zinc-rich primer.

[0030] The fiber-reinforced alcohol-soluble inorganic zinc-rich primer and its preparation method provided by this invention have the following significant advantages compared to the prior art:

[0031] (1) Excellent substrate wettability and adhesion

[0032] By modifying with organosilanes, the surface energy of the main agent solution can be optimized, improving the wettability of the primer on the steel substrate. On the other hand, it can provide additional chemical bonding anchoring sites, strengthening the interfacial bonding strength between the inorganic crosslinking network and the steel substrate.

[0033] (2) Excellent internal stress relief capability, impact resistance and thick film crack resistance

[0034] By precisely controlling the oligomer molecular weight (gel time) and modifying the inorganic backbone with organosilanes, the flexibility of the inorganic cross-linked network is enhanced. Simultaneously, the network doping of glass fibers disperses internal stress, effectively preventing brittle cracking of the coating during thick-film application or rapid temperature changes. Furthermore, the high strength of the glass fibers themselves significantly improves the coating's tensile strength and impact resistance, preventing cracking and peeling caused by external forces.

[0035] (3) Excellent storage stability and a wider curing humidity window

[0036] This invention employs a two-step polycondensation process, introducing a specialized hydrolysis regulator in the second stage to achieve precise control of the polycondensation process, resulting in silane hydrolysis products with narrow molecular weight distribution and high batch reproducibility. Combined with precise gel time design, the finished primer exhibits excellent curing activity, enabling coating film curing over a wider humidity range and significantly reducing the incidence of coating defects. Detailed Implementation

[0037] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0038] The polyethyl silicate used in this invention was purchased from Zhangjiagang Xinya Chemical Co., Ltd., and the polyethyl silicate was polyethyl silicate-40. The zinc powder was spherical 800-mesh zinc powder from Jiangsu Kecheng; the polyvinyl butyral resin was purchased from Guangdong Yuemei Chemical (Ford Cup viscosity 10s); and the organobentonite was Zhejiang Fenghong BS-1C organobentonite. The glass fiber was alkali-free glass fiber with a single strand diameter of 10±5 μm and a length of 300±50 μm.

[0039] The amounts of each component in Examples 1-3 are shown in the table below:

[0040] Table 1. Raw materials and dosages of components A and B in Examples 1-3

[0041]

[0042] The preparation methods of Examples 1-3 are as follows:

[0043] S1: Add anhydrous ethanol to the reaction vessel, heat to 40°C in a water bath, add polyethyl silicate, and stir under controlled temperature until homogeneous; add methyltriethoxysilane while stirring, mix well, and then add acidified water (deionized water and mixed acid) dropwise over 1-2 hours; after the gel time reaches 15-35 seconds, raise the temperature to 50°C, add dimethyldiethoxysilane, and stir well; slowly add hydrolysis regulator to the vessel over 0.5-1.5 hours, and then maintain the temperature for reaction until the gel time reaches 95-130 seconds. Cool and filter to obtain component A.

[0044] S2: According to the formula, add polyvinyl butyral resin and isopropanol into the feed tank and stir at room temperature to completely dissolve them to obtain polyvinyl butyral resin liquid; after the glass fiber and zinc powder are dry mixed evenly, they are added to the polyvinyl butyral resin liquid in batches and mixed evenly; then the filler and organic bentonite are added, dispersed at high speed and filtered to obtain component B.

[0045] S3: Mix components A and B at a mass ratio of 1:(4-5) until homogeneous to obtain fiber-reinforced inorganic zinc-rich primer.

[0046] Comparative Example 1:

[0047] The other conditions are the same as in Example 1, except that the hydrolysis regulator is replaced with an equal amount of a mixture of hydrochloric acid and sodium chloride.

[0048] Comparative Example 2:

[0049] Other conditions are the same as in Example 1, except that glass fiber is replaced with an equal amount of cellulose fiber (single fiber diameter 25±5μm, length 500±100μm).

[0050] Comparative Example 3:

[0051] The other conditions are the same as in Example 1, except that the organosilicon compound is replaced with an equal amount of polyethyl silicate.

[0052] Comparative Example 4:

[0053] Other conditions are the same as in Example 1, except that the amounts of mixed acid and deionized water are adjusted to 9 parts and 7.9 parts, respectively.

[0054] Impact resistance (forward impact), bending test, adhesion (pull-off method), drying time and salt spray resistance were tested on Examples 1-3 and Control Examples 1-3, respectively, in accordance with GB / T 1732-2020 "Determination of Impact Resistance of Paint Film", GB / T 6742-2007 "Bending Test (Cylindrical Shaft) of Paints and Varnishes", GB / T 5210-2006 "Adhesion Test by Pull-off Method of Paints and Varnishes", GB / T1728-2020 "Determination of Drying Time of Paint Film and Putty Film", and GB / T 10125-2021 "Civilized Atmosphere Corrosion Test - Salt Spray Test". The test results are recorded in Table 2.

[0055] Table 2 Performance test results of alcohol-soluble inorganic zinc-rich primers obtained from each example and control example

[0056]

[0057] Note: The test panels for impact resistance, bending test, and maximum single-coat thickness were all cured at 25°C and 60% humidity.

[0058] Compared to Example 1, Example 2 contains a higher amount of organosilicon compound. As shown in Table 2, after increasing the amount of organosilicon compound, the adhesion of the coating, tested using the pull-off method, was improved for both surface-treated steel plates compared to Example 1. This is because methyltriethoxysilane can reduce the cohesive force of the coating, resulting in a more uniform dispersion of the cohesive force, which is beneficial for improving coating adhesion; while increasing the proportion of dimethyldiethoxysilane helps reduce the brittleness of the coating, improves its flexibility, ensures the integrity of the coating, and reduces the formation of cracks.

[0059] Compared to Example 1, Example 3 uses a smaller amount of glass fiber. As can be seen from the data in Table 2, reducing the amount of glass fiber not only decreases the adhesion of the coating compared to Example 1, but also shortens the salt spray resistance time. This is because glass fiber can form a network structure in the coating, effectively dispersing stress, and its own corrosion resistance also improves the coating's salt spray resistance.

[0060] Hydrolysis regulators can adjust the pH value of polyethyl silicate hydrolysis, thereby promoting a stable forward reaction. In Comparative Example 1, the hydrolysis regulator was replaced with an equal amount of a mixture of hydrochloric acid and sodium chloride. This substituted mixture did not regulate the pH value during the reaction, resulting in an excessively low pH during polyethyl silicate hydrolysis. This accelerated the hydrolysis reaction, shortened the storage time of component A, and significantly reduced adhesion and salt spray resistance. This is because residual glacial acetic acid in the polyethyl silicate hydrolysate continues to promote the hydrolysis reaction during storage, causing the hydrolysate to form a gel in a shorter time. Simultaneously, the residual glacial acetic acid in the polyethyl silicate hydrolysate reacts with zinc powder when component A and component B are mixed, affecting the performance of the paint film.

[0061] Glass fiber primarily serves as physical reinforcement; its network structure within the coating effectively disperses stress, improving the tensile and impact resistance of the paint film. Comparative Example 2, where glass fiber was replaced with an equal amount of cellulose fiber (single fiber diameter 25±5μm, length 500±100μm), showed a significant decrease in impact resistance and adhesion compared to Example 1, which contained glass fiber. This is because the mechanical strength of the three-dimensional skeleton formed by cellulose fiber in the coating is far less than that of glass fiber. The shrinkage rate of the silicon-oxygen bond network formed by the hydrolysis and polycondensation reaction of polyethyl silicate is large, making it unable to effectively disperse and transfer concentrated stress when the coating is subjected to external forces, resulting in a significant reduction in the mechanical strength of the coating. Simultaneously, the weak chemical resistance of cellulose fiber reduces the coating's salt spray resistance.

[0062] Modification with organosilicon compounds not only improved the flexibility of the coating, but also enhanced its application performance and various mechanical properties. In Comparative Example 3, where the organosilicon compound was replaced with an equal amount of polyethyl silicate, the MEK wiping resistance of Comparative Example 3 was substandard, and its adhesion was also reduced. This is because zinc powder has poor interfacial compatibility with the steel substrate, and polyethyl silicate alone is insufficient to form strong covalent bonds with the substrate surface, resulting in a weak bond between the coating and the substrate and reduced interfacial adhesion.

[0063] In Comparative Example 4, the amounts of mixed acid and deionized water were adjusted to 9 parts and 7.9 parts, respectively. The excessive addition of acidified water led to an overly vigorous hydrolysis reaction of polyethyl silicate, significantly shortening the gel time and drastically reducing the stability of the resulting hydrolysate. Inorganic zinc-rich primers prepared using such hydrolysates exhibited rapid curing, but after surface curing, external moisture could not penetrate into the coating to participate in the internal curing reaction, resulting in a "dry surface, wet interior" phenomenon. Ultimately, this led to a significant reduction in all aspects of the coating's performance.

[0064] The above embodiments are some examples of the present invention, used only to describe the technical solutions of the present invention in detail, and not to limit the scope of the present invention. Other embodiments, modifications or equivalent substitutions made by those skilled in the art based on the present invention, should be considered within the scope of the claims of the present invention.

Claims

1. A fiber-reinforced alcohol-soluble inorganic zinc-rich primer, characterized in that... Composed of component A and component B in a mass ratio of 1:(3-8): Component A (main agent) consists of the following ingredients by weight: 60-70 parts of polyethyl silicate 12-18 parts deionized water 9-16 parts of anhydrous ethanol 1-3 parts mixed acid Hydrolysis regulator 1.0-2.5 parts 0.6-2.0 parts of organosilicon compound; Component B (paste) consists of the following ingredients by weight: 60-70 parts zinc powder 10-18 parts of filler Isopropyl alcohol 14.5-18.5 parts 1-3 parts of polyvinyl butyral resin 0.5-2.5 parts organic bentonite 0.5-1.5 parts glass fiber; The organosilicon compound is a mixture of methyltriethoxysilane and dimethyldiethoxysilane.

2. The fiber-reinforced alcohol-soluble inorganic zinc-rich primer according to claim 1, characterized in that... The polyethyl silicate mentioned is polyethyl silicate-40.

3. The fiber-reinforced alcohol-soluble inorganic zinc-rich primer according to claim 1, characterized in that... The mixed acid is a mixture of hydrochloric acid, lactic acid and glacial acetic acid, with a mass ratio of (0.3~2):(0.5~2):(0.5~2); the hydrolysis regulator is a mixture of glacial acetic acid and sodium acetate, with a mass ratio of (2~3):1; and the mass ratio of methyltriethoxysilane and dimethyldiethoxysilane is (1.5~3):

1.

4. The fiber-reinforced alcohol-soluble inorganic zinc-rich primer according to claim 1, characterized in that... The zinc powder is spherical 800-mesh zinc powder from Jiangsu Kecheng; the polyvinyl butyral resin is purchased from Guangdong Yuemei Chemical (copper cup viscosity 10s); and the organic bentonite is Zhejiang Fenghong BS-1C organic bentonite.

5. The fiber-reinforced alcohol-soluble inorganic zinc-rich primer according to claim 1, characterized in that... The filler is a mixture of silica powder, wet sericite powder and 1250 mesh talc powder, with a mass ratio of (4~8): (3~6): (4~6).

6. The fiber-reinforced alcohol-soluble inorganic zinc-rich primer according to claim 1, characterized in that... The glass fiber is alkali-free glass fiber with a single fiber diameter of 10±5 μm and a length of 300±50 μm.

7. A method for preparing the fiber-reinforced alcohol-soluble inorganic zinc-rich primer according to claim 1, characterized in that... The preparation method of components A and B includes the following steps: S1: Add anhydrous ethanol to the reaction vessel, heat in a water bath to 30-40℃, add polyethyl silicate, and stir under controlled temperature until uniformly mixed; while stirring, first add methyltriethoxysilane, mix well, then add deionized water and mixed acid dropwise, completing the addition within 1-2 hours; after sampling and testing the gel time to 15-35 seconds, raise the temperature to 50℃, then add dimethyldiethoxysilane and stir until uniformly mixed; slowly add hydrolysis regulator to the vessel, completing the addition within 0.5-1.5 hours, then maintain the temperature for reaction until the gel time reaches 95-130 seconds, cool, and filter to obtain component A; S2: According to the formula, add polyvinyl butyral resin and isopropanol into the material tank, stir at room temperature to completely dissolve, and obtain polyvinyl butyral resin liquid; after the glass fiber and zinc powder are dry mixed evenly, add them to the polyvinyl butyral resin liquid in batches and mix evenly; then add filler and organic bentonite, disperse at high speed and filter to obtain component B. S3: Mix components A and B evenly to obtain fiber-reinforced inorganic zinc-rich primer.

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