Corrosion-resistant high-strength epoxy resin oily primer and preparation method thereof

Abstract

The invention discloses a corrosion-resistant high-strength epoxy resin oil-based primer and a preparation method thereof, and belongs to the technical field of coatings. The corrosion-resistant high-strength epoxy resin oil-based primer is prepared from the following components in parts by weight: 100 parts of epoxy resin, 60 to 70 parts of modified anti-rust pigment, 15 to 25 parts of reinforcing filler, 40 to 50 parts of mica iron oxide, 40 to 50 parts of curing agent, 1 to 3 parts of anti-settling agent and 0.2 to 0.7 part of flatting agent. The preparation method comprises the following steps: dispersing epoxy resin in a mixed solvent to obtain a resin base material, adding the modified anti-rust pigment, micaceous iron oxide, the reinforcing filler and the anti-settling agent into the resin base material, mixing and grinding, finally adding the curing agent and the leveling agent, mixing and sieving to obtain the anti-rust paint. According to the invention, erosion is blocked through a passive film, a hydroxide / oxyhydroxide film or bond energy advantage generated by the modified anti-rust pigment, so that the primer has excellent acid resistance, alkali resistance and salt spray corrosion resistance, and in addition, the primer has excellent mechanical strength by adding the reinforcing filler and micaceous iron oxide.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to a corrosion-resistant high-strength epoxy resin oil-based primer and a preparation method thereof. Background Art

[0002] Epoxy resin primer is widely used in various industrial fields due to its excellent adhesion, corrosion resistance and mechanical properties. The epoxy resin structure is stable, making the coating resistant to acid, alkali and organic solvents. After curing, the structure is dense and the anti-seepage performance is strong. It has excellent adhesion to various materials such as metal, cement, fiberglass and so on.

[0003] Although epoxy resin has a certain degree of corrosion resistance, its corrosion resistance is still insufficient in environments with strong acids, strong bases, or high salt concentrations. It is easily penetrated by corrosive media, causing the coating to fail. It is also prone to powdering when exposed to sunlight for a long time, with poor decorative properties and difficulty maintaining gloss. In addition, the impact resistance of epoxy resin primer is relatively weak, and it is prone to cracking or peeling when subjected to external impact, reducing the protective effect of the coating. In zinc-rich anti-corrosion coatings, zinc exists in the form of elemental particles, which will reduce the mechanical properties of the coating. After the zinc is consumed, free zinc ions will be produced, causing pollution to the ocean and other environments.

[0004] In summary, epoxy resin primer has obvious defects in corrosion protection and mechanical strength, and its performance needs to be improved by improving the formulation and process to meet more demanding use environments and application requirements. Summary of the Invention

[0005] Based on the deficiencies of the prior art, the object of the present invention is to provide a corrosion-resistant high-strength epoxy resin oil-based primer and a preparation method thereof.

[0006] The first aspect of the present invention is to provide a corrosion-resistant high-strength epoxy resin oil-based primer, comprising the following components in parts by weight: 100 parts of epoxy resin, 60-70 parts of modified anti-rust pigment, 15-25 parts of reinforcing filler, 40-50 parts of micaceous iron oxide, 40-50 parts of curing agent, 1-3 parts of anti-settling agent, and 0.2-0.7 parts of leveling agent; The modified anti-rust pigment is aminopolysiloxane-zinc phosphate, which is prepared by the following steps: (1) Dispersing zinc phosphate in a solvent and adding a pH regulator to obtain pretreated zinc phosphate; (2) Add aminopolysiloxane to the pretreated zinc phosphate, mix and react, and then dry to obtain aminopolysiloxane-zinc phosphate.

[0007] It should be noted that the Zn-OH group obtained by the hydrolysis of zinc ions on the surface of zinc phosphate is protonated in an acidic ethanol environment, and the ethoxy group at the end of aminopolyoxysilane is hydrolyzed into silanol, and the positively charged ≡Zn-OH2 +With negatively charged ≡Si-O - (Silanol deprotonation) generates electrostatic attraction to form ion pairs, which are driven to dehydrate under heat of 50-70°C to form ≡Si-O-Zn≡ covalent bonds. This covalent bond runs through the resin, can absorb external stress, and reduce the occurrence of coating shedding and cracking.

[0008] Acid corrosion during service caused local H + As the concentration increases, the Si-OH groups on the surface of aminopolysiloxane-zinc phosphate that are not involved in bonding generate ≡Si-OH2 + ,≡Si-OH2 + Adsorption of PO4 3- Forming a phosphate ion enrichment layer, enriched PO4 3- Attract metal ions such as Fe dissolved from the metal substrate anode 2+ , a precipitation reaction occurs to form a passivation film, thereby preventing further corrosion of the acid; when encountering alkali corrosion, OH - As the concentration increases, hydroxyl ions dissolve the oxide film on the surface of the metal substrate and release divalent metal ions (such as Fe 2+ / Zn 2+ ), -NH2 of aminopolysilane coordinates with metal ions and forms hydroxide / oxyhydroxide (such as FeOOH / Zn(OH)2) composite film through dissolution oxidation and hydrolysis reaction. This composite film can effectively protect the metal substrate and prevent further corrosion; in high salt environment, Cl - With ≡Si-O - Competitive binding of Zn 2+ Since the ≡Si-O-Zn bond energy is significantly higher than the Zn-Cl bond energy, chloride ion corrosion needs to overcome a higher bond energy, thereby reducing the chloride ion permeability and reducing salt corrosion.

[0009] In some embodiments, the weight ratio of zinc phosphate to aminopolysilane is 100:2-5.

[0010] In some embodiments, the solvent is selected from at least one of ethanol, isopropanol, methanol, and ethylene glycol ethyl ether; and the pH adjuster is selected from at least one of glacial acetic acid, lactic acid, citric acid, and hydrochloric acid.

[0011] In some embodiments, the pH adjuster adjusts the pH to 4.5-5.5.

[0012] In some embodiments, in step (2), the mixing reaction temperature is 50-70°C, the mixing reaction time is 1.5-2.5 h, and the drying temperature is 75-85°C.

[0013] The second aspect of the present invention is to provide a method for preparing a corrosion-resistant high-strength epoxy resin oil-based primer, comprising the following steps: S1: dispersing epoxy resin in a mixed solvent to obtain a resin base; S2: Add modified anti-rust pigment, mica iron oxide, reinforcing filler and anti-settling agent to the resin base, mix and grind; S3: Add curing agent and leveling agent to the mixed system of S2, mix and sieve to obtain corrosion-resistant high-strength epoxy resin oil-based primer.

[0014] In some embodiments, the anti-settling agent is selected from at least one of organic bentonite and polyamide wax slurry; the curing agent is selected from at least one of polyamide, phenolic amine, and alicyclic amine adduct; and the leveling agent is selected from at least one of polyether-modified polysiloxane and fluorocarbon-modified acrylate.

[0015] In some embodiments, the mixed solvent is formed by mixing xylene and n-butanol in a mass ratio of 6-8:3; the reinforcing filler is formed by mixing glass flakes and silane-modified aluminum borate whiskers in a mass ratio of 4-6:0.5-1.5.

[0016] In some embodiments, in S2, the grinding is performed to a fineness of ≤40 μm.

[0017] The purpose of limiting the grinding fineness is to eliminate the hidden danger of sedimentation of the reinforcing filler and facilitate its uniform dispersion.

[0018] In some embodiments, in S3, the mixing temperature is 35-45° C., and the mixing stirring speed is 200-400 rpm.

[0019] The mixing is carried out at low temperature and low speed to avoid pre-reaction of amine curing agent caused by high temperature, and at the same time to make the leveling agent evenly distributed and eliminate shrinkage holes.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention bridges the resin and filler through ≡Si-O-Zn covalent bonds to form a penetrating network, eliminating physical interface weaknesses. The rigid bonded skeleton can disperse mechanical stress and inhibit the appearance and expansion of microcracks. The long polysiloxane chain can also absorb impact energy, achieving a balance of strength and toughness. In addition, aminopolysiloxane-zinc phosphate can cope with corrosion in acidic, alkaline and high-salt environments, and blocks erosion by forming a passivation film, a hydroxide / oxyhydroxide composite film, and bond energy advantages, further improving the corrosion resistance and mechanical properties of the primer.

[0021] 2. The corrosion-resistant high-strength epoxy resin oil-based primer provided by the present invention also includes reinforcing fillers. The glass flakes stacked in parallel in the resin matrix can block tiny corrosion channels and absorb part of the impact force. The silane-modified aluminum borate whiskers are interspersed in the resin matrix. In addition to improving the tensile strength of the primer and preventing crack expansion, it can also support the glass flakes and prevent them from storage and sedimentation. In addition, the present invention also adds mica iron oxide, which realizes physical shielding through large-area stacking. In addition to providing rigid support, it can also cooperate with the glass flakes to further extend the penetration path of the corrosive medium and slow down the corrosion rate. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to specific embodiments.

[0023] Example 1 A corrosion-resistant, high-strength epoxy resin oil-based primer comprising the following components in parts by weight: 100 parts of epoxy resin, 65 parts of modified anti-rust pigment, 20 parts of reinforcing filler, 45 parts of mica iron oxide, 450 parts of curing agent, 2 parts of anti-settling agent, and 0.5 parts of leveling agent; The modified anti-rust pigment is aminopolysiloxane-zinc phosphate, which is prepared by the following steps: (1) Dispersing zinc phosphate in ethanol, adding glacial acetic acid to adjust the pH to 4.5-5.5, to obtain pretreated zinc phosphate; (2) Add aminopolysiloxane to the pretreated zinc phosphate, mix and react at 60°C for 2 h, and then dry at 80°C to obtain aminopolysiloxane-zinc phosphate.

[0024] The weight ratio of zinc phosphate to aminopolysilane is 100:4.

[0025] The above-mentioned corrosion-resistant high-strength epoxy resin oil-based primer is prepared by the following steps: S1: dispersing epoxy resin in a mixed solvent to obtain a resin base; S2: Add modified anti-rust pigment, mica iron oxide, reinforcing filler and anti-settling agent to the resin base, mix and grind to a fineness of ≤40 μm; S3: Add curing agent and leveling agent to the mixed system of S2, mix at 40°C and 300 rpm, and then sieve to obtain corrosion-resistant high-strength epoxy resin oil-based primer.

[0026] Example 2 It is basically the same as Example 1, with the only difference being: The corrosion-resistant high-strength epoxy resin oil-based primer provided in this embodiment includes the following components in parts by weight: 100 parts of epoxy resin, 70 parts of modified anti-rust pigment, 25 parts of reinforcing filler, 50 parts of mica iron oxide, 50 parts of curing agent, 3 parts of anti-settling agent, and 0.7 parts of leveling agent.

[0027] Example 3 It is basically the same as Example 1, with the only difference being: The corrosion-resistant high-strength epoxy resin oil-based primer provided in this embodiment includes the following components in parts by weight: 100 parts of epoxy resin, 60 parts of modified anti-rust pigment, 15 parts of reinforcing filler, 40 parts of mica iron oxide, 40 parts of curing agent, 1 part of anti-settling agent, and 0.2 parts of leveling agent.

[0028] Example 4 It is basically the same as Example 1, with the only difference being: The aminopolysiloxane-zinc phosphate provided in this embodiment is prepared by the following steps: (1) Dispersing zinc phosphate in isopropyl alcohol, adding lactic acid to adjust the pH to 4.5-5.5, and obtaining pretreated zinc phosphate; (2) Add aminopolysiloxane to the pretreated zinc phosphate, mix and react at 70°C for 2.5 h, and then dry at 85°C to obtain aminopolysiloxane-zinc phosphate.

[0029] Example 5 The same as the embodiment, except that: The aminopolysiloxane-zinc phosphate provided in this embodiment is prepared by the following steps: (1) Dispersing zinc phosphate in methanol, adding citric acid to adjust the pH to 4.5-5.5, to obtain pretreated zinc phosphate; (2) Add aminopolysiloxane to the pretreated zinc phosphate, mix and react at 50°C for 1.5 h, and then dry at 75°C to obtain aminopolysiloxane-zinc phosphate.

[0030] Comparative Example 1 The method is basically the same as Example 1, except that the modified anti-rust pigment is replaced with the same amount of zinc phosphate.

[0031] Comparative Example 2 The process is basically the same as Example 1, except that during the preparation of the modified anti-rust pigment, the aminopolysiloxane is replaced with an equal amount of methylpolysiloxane.

[0032] Comparative Example 3 The method is basically the same as Example 1, except that no reinforcing filler is added and the amount of reinforcing filler is superimposed on mica iron oxide.

[0033] In order to prove that the corrosion-resistant high-strength epoxy resin oil-based primer provided by the present invention has excellent corrosion resistance and high mechanical strength, the epoxy primers provided in Examples 1-5 and Comparative Examples 1-3 are applied to the surface of the steel plate according to the common method used by people in this field, and a 50μm coating is formed after natural drying. The performance test is then carried out, and the test results are shown in Table 1.

[0034] Table 1 As can be seen from Table 1, the oil-based primers provided in Examples 1-5 have excellent acid resistance, alkali resistance, and salt spray corrosion resistance, and have high mechanical strength, good tensile strength, and impact resistance. Combined with the comparative examples, it can be seen that comparative example 1 adds zinc phosphate that has not been modified by aminosilanization, resulting in a significant decrease in corrosion resistance, only a weak anti-rust function, and a decrease in mechanical support capacity; comparative example 2 replaces aminopolysilane with methylpolysilane, which loses the catalytic passivation and self-repair function of -NH2, resulting in reduced alkali resistance; comparative example 3 lacks reinforcing fillers, resulting in the opening of small corrosion channels, which accelerates the invasion speed of the corrosive medium and reduces the supporting capacity of the primer.

[0035] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A corrosion-resistant high-strength epoxy resin oil-based primer, characterized in that: The invention comprises the following components in parts by weight: 100 parts of epoxy resin, 60-70 parts of modified anti-rust pigment, 15-25 parts of reinforcing filler, 40-50 parts of mica iron oxide, 40-50 parts of curing agent, 1-3 parts of anti-settling agent, and 0.2-0.7 parts of leveling agent; The modified anti-rust pigment is aminopolysiloxane-zinc phosphate, which is prepared by the following steps: (1) Dispersing zinc phosphate in a solvent and adding a pH regulator to obtain pretreated zinc phosphate; (2) Adding aminopolysiloxane to the pretreated zinc phosphate, mixing and reacting, and then drying to obtain aminopolysiloxane-zinc phosphate.

2. The corrosion-resistant high-strength epoxy resin oil-based primer according to claim 1, characterized in that: The weight ratio of the zinc phosphate to the aminopolysiloxane is 100:2-5.

3. The corrosion-resistant high-strength epoxy resin oil-based primer according to claim 1, characterized in that: The solvent is selected from at least one of ethanol, isopropanol, methanol, and ethylene glycol ethyl ether; and the pH adjuster is selected from at least one of glacial acetic acid, lactic acid, citric acid, and hydrochloric acid.

4. The corrosion-resistant high-strength epoxy resin oil-based primer according to claim 3, characterized in that: The pH value is adjusted to 4.5-5.5 by the pH adjuster.

5. The corrosion-resistant high-strength epoxy resin oil-based primer according to claim 1, characterized in that: In the step (2), the mixing reaction temperature is 50-70°C, the mixing reaction time is 1.5-2.5 h, and the drying temperature is 75-85°C.

6. A method for preparing a corrosion-resistant high-strength epoxy resin oil-based primer, characterized in that: The following steps are involved: S1: dispersing epoxy resin in a mixed solvent to obtain a resin base; S2: adding modified anti-rust pigment, mica iron oxide, reinforcing filler and anti-settling agent to the resin base material, mixing and grinding; S3: Add curing agent and leveling agent to the mixed system of S2, mix and sieve to obtain corrosion-resistant high-strength epoxy resin oil-based primer.

7. The method for preparing the corrosion-resistant high-strength epoxy resin oil-based primer according to claim 6, characterized in that: The anti-settling agent is selected from at least one of organic bentonite and polyamide wax slurry; the curing agent is selected from at least one of polyamide, phenolic amine and alicyclic amine adduct; the leveling agent is selected from at least one of polyether modified polysiloxane and fluorocarbon modified acrylate.

8. The method for preparing the corrosion-resistant high-strength epoxy resin oil-based primer according to claim 6, characterized in that: The mixed solvent is formed by mixing xylene and n-butanol in a mass ratio of 6-8:3; the reinforcing filler is formed by mixing glass flakes and silane-modified aluminum borate whiskers in a mass ratio of 4-6:0.5-1.

5.

9. The method for preparing the corrosion-resistant high-strength epoxy resin oil-based primer according to claim 6, characterized in that: In the S2, the powder is ground to a fineness of ≤40 μm.

10. The method for preparing the corrosion-resistant high-strength epoxy resin oil-based primer according to claim 6, characterized in that: In the step S3, the mixing temperature is 35-45° C., and the mixing stirring speed is 200-400 rpm.

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