A vulcanized rubber modified acrylic emulsion for steel corrosion protection and preparation method thereof

Abstract

The present invention relates to the field of coating technology, in particular to the field of IPC C09D1, and more specifically to a vulcanized rubber modified acrylic emulsion for steel corrosion protection and a preparation method thereof. The components include: acrylic resin emulsion, vulcanized rubber emulsion and emulsifier, and both ends of the rubber molecule in the vulcanized rubber emulsion contain mercapto groups, wherein one end of the mercapto group is grafted with benzothiazole, and the other end of the mercapto group is modified by water-based modification. When used as a coating, the anti-corrosion performance of the film layer can be effectively improved to meet the use requirements of the anti-corrosion of steel substrates; the long-chain monomer includes at least one of dodecyl acrylate and hexadecyl acrylate, which improves the hydrophobic performance, so that the contact angle of the vulcanized rubber modified acrylic emulsion is between 100-120°, preventing water from penetrating and contacting the steel substrate, and further improving the dispersion performance with the vulcanized rubber emulsion.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to the field of IPC C09D1, and more specifically to a vulcanized rubber modified acrylic emulsion for steel corrosion protection and a preparation method thereof. Background Art

[0002] Metal corrosion is the great damage caused to metal equipment by the chemical reaction between metal and the medium it contacts. Metal corrosion is a problem that metal equipment has always faced during its service life. The most commonly used anti-corrosion method is to cover the metal surface with a metal, non-metal or metal-non-metal composite film as a protective layer through physical, chemical or electrochemical processes to prevent or slow down the chemical reaction between the metal and the medium it contacts. There are many ways to achieve corrosion protection for steel substrates, such as thermal spraying alloys, electrogalvanizing, zinc-chromium coatings (Dacromet), zinc-nickel diffusion layers, surface phosphating treatments and organic coatings. Among them, the method of coating the surface of the substrate with anti-corrosion coatings is the most effective means. Among them, the use of water-based anti-corrosion coatings is the focus and difficulty of current research. How to design and prepare water-based resins with high-efficiency anti-corrosion is an urgent problem that needs to be solved in the industry.

[0003] CN102206459A discloses a high-performance solvent-free epoxy anti-corrosion coating for steel surface and a preparation method thereof. The high-performance solvent-free epoxy anti-corrosion coating comprises component A and component B. The percentage content of component A is as follows: component A comprises epoxy resin 830 (40%), epoxy resin 618 (30%), and toughening agent (polyurethane type epoxy resin, homemade, 30%); component B comprises amine curing agent (50%), zinc phosphate (10%), aluminum tripolyphosphate (10%), mica iron oxide (10%), talcum powder (800 mesh, 5%), precipitated barium sulfate (800 mesh, 2%), and aluminum powder (13%); CN105255313A discloses a super anti-corrosion epoxy zinc-rich coating and a preparation method thereof. The coating comprises component A and component B, wherein component A comprises 12-16 parts of organosilicon modified resin, 10-40 parts of inorganic filler, 4-8 parts of zinc powder, 15-21 parts of pigment, 4-8 parts of aromatic hydrocarbons, 10-23 parts of organic solvent, 6-19 parts of coupling agent, 1-3 parts of auxiliary agent, and component B comprises 10-25 parts of curing agent. The above anticorrosive coating is an oily or solvent-free system, and has poor anticorrosive performance, poor adaptability, and non-compliance with environmental protection standards. Summary of the invention

[0004] The first aspect of the present invention provides a vulcanized rubber modified acrylic emulsion for steel corrosion protection, the components of which include: acrylic resin emulsion, vulcanized rubber emulsion and emulsifier, both ends of the rubber molecules in the vulcanized rubber emulsion contain mercapto groups, one end of the mercapto group is grafted with benzothiazole, and the other end of the mercapto group is modified to be water-based.

[0005] The applicant has found that both ends of the rubber molecules in the vulcanized rubber emulsion contain mercapto groups, one end of which is grafted with benzothiazole, and the other end of which is modified by water-based modification. When used as a coating, it can effectively improve the anti-corrosion performance of the film layer and meet the requirements for anti-corrosion of steel substrates. It may be that the double-terminal mercapto structure increases the activity of the modification reaction, and benzothiazole is more likely to undergo addition reaction with the mercapto group, thereby passivating the benzothiazole group and the substrate, significantly reducing the oxidation activity of the metal.

[0006] The other end mercapto group and the epoxy group are modified to be water-based through a ring-opening reaction.

[0007] The water absorption rate of the vulcanized rubber modified acrylic emulsion after coating is not higher than 4%.

[0008] The contact angle of the vulcanized rubber modified acrylic emulsion is 100-120°.

[0009] The raw materials for preparing the acrylic resin emulsion include long-chain monomers, and the long-chain monomers include at least one of lauryl acrylate and hexadecyl acrylate.

[0010] The applicant has found that the raw materials for preparing the acrylic resin emulsion include long-chain monomers, and the long-chain monomers include at least one of lauryl acrylate and hexadecyl acrylate, which improves the hydrophobicity and makes the contact angle of the vulcanized rubber modified acrylic emulsion between 100-120°, preventing water from penetrating and contacting the steel substrate. At the same time, it can further improve the dispersion performance with the vulcanized rubber emulsion. It may be that the long alkyl chain structure improves the entanglement and disentanglement effect with the rubber segment, forming a similar interpenetrating network structure, and the molecular segments are fixed to each other after the emulsion is dried.

[0011] The added amount of the emulsifier accounts for 20-100wt% of the vulcanized rubber emulsion.

[0012] Preferably, the amount of the emulsifier added accounts for 50wt% of the vulcanized rubber emulsion.

[0013] Preferably, the raw materials for preparing the acrylic resin emulsion further include soft monomers, hard monomers, benzene ring-containing monomers, hydroxyl monomers, emulsifiers, initiators and deionized water.

[0014] Preferably, at least one of butyl acrylate (BA) and isooctyl acrylate (EHA).

[0015] Preferably, the benzene ring-containing monomer includes styrene (St).

[0016] Preferably, the hard monomer includes at least one of methyl acrylate (MA) and methyl methacrylate (MMA).

[0017] Preferably, the hydroxy monomer includes at least one of hydroxyethyl acrylate and hydroxypropyl acrylate.

[0018] The initiator includes at least one of potassium persulfate (KPS) or ammonium persulfate (APS).

[0019] Further preferably, the preparation of the acrylic resin emulsion includes, by weight percentage, 5-15% long-chain monomer, 20-40% soft monomer, 10-25% hard monomer, 15-35% benzene ring-containing monomer, 2-8% hydroxyl monomer, 0.5-1.5% emulsifier, 0.1-2% initiator, and deionized water makes up the balance.

[0020] The applicant has found that by limiting the long-chain monomers in the acrylic resin emulsion to 5-15%, the soft monomers to 20-40%, the hard monomers to 10-25%, the benzene ring-containing monomers to 15-35%, and the hydroxyl monomers to 2-8%, the density of the film layer can be further improved, and at the same time, the mechanical properties of the film layer can be improved. This may be due to the combined effect of specific monomers and multiple active groups, which improves the cross-linking point density and the uniformity of the distribution of the cross-linking points.

[0021] Preferably, the emulsifier includes at least one of OP-10 (condensation product of alkylphenol and ethylene oxide), SDS (sodium dodecyl sulfate), and PCA078 (dodecyl ether sulfate).

[0022] The raw materials for preparing the vulcanized rubber emulsion include: vulcanized rubber, benzothiazole (CAS: 256414-72-9), acrylic monomer containing epoxy group, catalyst, first solvent and second solvent.

[0023] Preferably, the vulcanized rubber is homemade, specifically a polymerized sulfur copolymer containing 10 wt% limonene. The specific synthesis method is described in patent CN104844772B, paragraphs 49-51 of the specification.

[0024] Preferably, the epoxy group-containing acrylic monomer includes at least one of glycidyl methacrylate, glycidyl acrylate, glycidyl neodecanoate, and glycidyl methacrylate.

[0025] Preferably, the first solvent includes one of toluene, xylene, propylene glycol methyl ether and butyl acetate.

[0026] Preferably, the second solvent includes one of toluene, xylene, propylene glycol methyl ether and butyl acetate.

[0027] Preferably, the catalyst includes one of tetramethylammonium hydroxide, tetrabutylammonium fluoride, and an organic tin catalyst.

[0028] The second aspect of the present invention provides a method for preparing a vulcanized rubber modified acrylic emulsion for steel corrosion protection, comprising the following steps:

[0029] S1, preparing acrylic resin emulsion;

[0030] S2, preparing vulcanized rubber emulsion;

[0031] S3, uniformly mix the vulcanized rubber latex and the emulsifier, and add the acrylic resin latex to obtain.

[0032] The specific steps of preparing the acrylic resin emulsion include: mixing all monomers; uniformly mixing 20-40wt% of the mixture of the total monomers, deionized water, an initiator and an emulsifier, and pre-emulsifying to obtain a pre-emulsified product; dripping the remaining monomers into the pre-emulsified product for 0.5-3h, and continuing the reaction for 2-10h to obtain the product.

[0033] The method for preparing the vulcanized rubber emulsion comprises the following steps:

[0034] Step 1: adding vulcanized rubber, benzothiazole and a catalyst into a first solvent to react to obtain an intermediate;

[0035] Step 2: Adding an acrylic monomer containing an epoxy group and a second solvent to the intermediate, and reacting to obtain the product.

[0036] The epoxy group-containing acrylic monomer is glycidyl methacrylate, the first solvent and the second solvent are both toluene, and the catalyst is tetramethylammonium hydroxide.

[0037] The molar ratio of the vulcanized rubber to benzothiazole is 1:0.8 to 1:1.2.

[0038] The reaction temperature in step 1 is 50-120° C., and the reaction time is 3-8 hours.

[0039] In the step 1, the amount of the catalyst used is 0.5-5 wt % of the vulcanized rubber and benzothiazole.

[0040] The molar ratio of the intermediate to the epoxy group-containing acrylic monomer is 1:0.8 to 1:1.2.

[0041] The reaction temperature in step 2 is 60-150° C., and the reaction time is 4-12 hours.

[0042] The amount of the catalyst used in step 2 is 0.2-5 wt % of the intermediate and the acrylic monomer containing epoxy groups.

[0043] Preferably, the mass ratio of the acrylic resin emulsion to the vulcanized rubber emulsion is (2-5):1.

[0044] The applicant has found that the mass ratio of the acrylic resin emulsion and the vulcanized rubber emulsion is (2-5):1, and the emulsifier includes at least one of OP-10 (condensation product of alkylphenol and ethylene oxide), SDS (sodium dodecyl sulfate), and PCA078 (dodecyl ether sulfate), which can make the water absorption rate of the vulcanized rubber modified acrylic emulsion after coating not higher than 4%. This may be due to the regulation of the small size and size uniformity of the acrylic emulsion and vulcanized rubber emulsion particles, thereby improving the stacking density of the latex ions after drying.

[0045] Beneficial Effects

[0046] 1. The water-based resin coating prepared in this application has strong adaptability, meets environmental protection requirements, and has excellent anti-corrosion properties.

[0047] 2. By limiting the long-chain monomer to 5-15%, the soft monomer to 20-40%, the hard monomer to 10-25%, the benzene ring-containing monomer to 15-35%, and the hydroxyl monomer to 2-8% in the acrylic resin emulsion, the density of the film layer can be further improved, and at the same time, the mechanical properties of the film layer can be improved.

[0048] 3. The mass ratio of the acrylic resin emulsion to the vulcanized rubber emulsion is (2-5):1, and the emulsifier includes OP-10

[0049] At least one of (condensation product of alkylphenol and ethylene oxide), SDS (sodium dodecyl sulfate), PCA078 (dodecyl ether sulfate) can make the water absorption rate of the vulcanized rubber modified acrylic emulsion coating film no more than 4%.

[0050] 4. Both ends of the rubber molecules in the vulcanized rubber latex contain mercapto groups, one end of which is grafted with benzothiazole.

[0051] The mercapto group at the other end is modified by water-based treatment and used as a coating, which can effectively improve the anti-corrosion performance of the film layer and meet the anti-corrosion requirements of steel substrates.

[0052] 5. The raw materials for preparing the acrylic resin emulsion include long-chain monomers, and the long-chain monomers include at least one of lauryl acrylate and hexadecyl acrylate, which improves the hydrophobicity, so that the contact angle of the vulcanized rubber modified acrylic emulsion is between 100-120°, preventing water from penetrating and contacting the steel substrate, and further improving the dispersion performance with the vulcanized rubber emulsion. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The red one is Example 1, the blue one is Example 3, the yellow one is Example 5, the green one is Example 7, and the purple one is Comparative Example 1. DETAILED DESCRIPTION

[0054] Examples 1-9

[0055] A vulcanized rubber modified acrylic emulsion for steel corrosion protection comprises acrylic resin emulsion, vulcanized rubber emulsion and emulsifier.

[0056] A method for preparing a vulcanized rubber modified acrylic emulsion for steel corrosion protection comprises the following steps:

[0057] S1, preparing acrylic resin emulsion;

[0058] S2, preparing vulcanized rubber emulsion;

[0059] S3, uniformly mix the vulcanized rubber latex and the emulsifier, and add the acrylic resin latex to obtain.

[0060] The emulsifier is OP-10, and the added amount of the emulsifier accounts for 50wt% of the vulcanized rubber emulsion.

[0061] The specific steps of preparing the acrylic resin emulsion include: mixing all monomers; uniformly mixing 30wt% of the mixture of the total monomers, deionized water, an initiator and an emulsifier, pre-emulsifying to obtain a pre-emulsified product; dropping the remaining monomers into the pre-emulsified product, and then carrying out a heat-insulating reaction to obtain the product.

[0062] The formula and preparation parameters of the acrylic resin emulsion are shown in Table 1.

[0063] The preparation of the vulcanized rubber emulsion comprises the following steps:

[0064] Step 1: adding vulcanized rubber, benzothiazole and a catalyst into a first solvent (30 wt% relative to the modified vulcanized rubber) to react to obtain an intermediate;

[0065] Step 2: Adding an epoxy group-containing acrylic monomer and a second solvent (relative to the modified vulcanized rubber, 20 wt %) into the intermediate, and reacting to obtain the product.

[0066] The vulcanized rubber is self-made, specifically a polymerized sulfur copolymer containing 10 wt% limonene. The specific synthesis method is described in patent CN104844772B, paragraphs 49-51 of the specification.

[0067] The epoxy group-containing acrylic monomer is glycidyl methacrylate, the first solvent and the second solvent are both toluene, and the catalyst is tetramethylammonium hydroxide.

[0068] The molar ratio of the vulcanized rubber to benzothiazole is 1:1.

[0069] The reaction temperature in step 1 is 85° C. and the reaction time is 6 h.

[0070] The amount of the catalyst used in step 1 is 0.5 wt % of the vulcanized rubber and benzothiazole.

[0071] The molar ratio of the intermediate to the epoxy group-containing acrylic monomer is 1:1.

[0072] The reaction temperature in step 2 is 105° C. and the reaction time is 8 h.

[0073] The amount of catalyst used in step 2 is 0.2wt% of the intermediate and the acrylic monomer containing epoxy groups. The mass ratio of the acrylic resin emulsion to the vulcanized rubber emulsion is 3:1.

[0074] Table 1

[0075]

[0076]

[0077] Comparative Example 1

[0078] An acrylic resin emulsion, comprising: acrylic resin emulsion, the formula and preparation method of the acrylic resin emulsion are the same as those in Example 1.

[0079] Performance Testing Methods

[0080] 1. Contact angle test: The test method refers to the contact angle test standard for plastics, "GB / T 30693-2014 Measurement of contact angle between plastic film and water"

[0081] 2. Swelling test: The resin emulsion is coated on the steel surface (average dry film thickness 150μm). After the whole surface is immersed for 15 days, the quality change before and after immersion is tested.

[0082] The test results are shown in Table 2.

[0083] Performance test data

[0084] Table 2

[0085] Contact angle° Water absorption % Example 1 105.8 3.70 Example 2 109.3 3.56 Example 3 108.4 4.01 Example 4 103.5 3.45 Example 5 104.4 3.67 Example 6 106.9 3.21 Example 7 107.1 3.78 Example 8 104.3 3.89 Example 9 106.8 3.26 Comparative Example 1 85.5 11.22

Claims

1. A vulcanized rubber modified acrylic emulsion for steel corrosion protection, characterized in that: The components include: acrylic resin emulsion, vulcanized rubber emulsion and emulsifier, wherein both ends of the rubber molecule in the vulcanized rubber emulsion contain mercapto groups, wherein the mercapto groups at one end are grafted with benzothiazole, and the mercapto groups at the other end are modified to be water-based; The mass ratio of the acrylic resin emulsion to the vulcanized rubber emulsion is (2-5):1, and the emulsifier includes at least one of OP-10, SDS, and PCA078; The raw materials for preparing the acrylic resin emulsion include long-chain monomers, and the long-chain monomers include at least one of lauryl acrylate and hexadecyl acrylate.

2. The vulcanized rubber modified acrylic emulsion for steel corrosion protection according to claim 1, characterized in that: The other end mercapto group and the epoxy group are modified to be water-based through a ring-opening reaction.

3. The vulcanized rubber modified acrylic emulsion for steel corrosion protection according to claim 2, characterized in that: The water absorption rate of the vulcanized rubber modified acrylic emulsion after coating is not higher than 4%.

4. The vulcanized rubber modified acrylic emulsion for steel corrosion protection according to claim 3, characterized in that: The contact angle of the vulcanized rubber modified acrylic emulsion is 100-120°.

5. The vulcanized rubber modified acrylic emulsion for steel corrosion protection according to claim 1, characterized in that: The raw materials for preparing the vulcanized rubber emulsion include: vulcanized rubber, benzothiazole, acrylic monomer containing epoxy group, catalyst, first solvent and second solvent.

6. The vulcanized rubber modified acrylic emulsion for steel corrosion protection according to claim 5, characterized in that: The preparation method of the vulcanized rubber emulsion comprises the following steps: Step 1: adding vulcanized rubber, benzothiazole and a catalyst into a first solvent to react to obtain an intermediate; Step 2: Adding an acrylic monomer containing an epoxy group and a second solvent to the intermediate, and reacting to obtain the product.

7. A method for preparing the vulcanized rubber modified acrylic emulsion for steel corrosion protection according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, preparing acrylic resin emulsion; S2, preparing vulcanized rubber latex; S3, uniformly mix the vulcanized rubber latex and the emulsifier, and add the acrylic resin latex to obtain.

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