CN115353795A - A kind of high-resistance waterborne epoxy zinc-rich primer and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of water-based anticorrosive coatings, and particularly discloses a high-resistance water-based epoxy zinc-rich primer and a preparation method thereof. The primer consists of a component A and a component B, wherein the component A comprises: 4.0 to 5.0 percent of modified alicyclic amine aqueous curing agent, 3.2 to 4.0 percent of modified polyamide aqueous curing agent, 3.0 to 7.0 percent of film forming additive, 25.0 to 35.0 percent of 500-mesh spherical zinc powder, 40.0 to 50.0 percent of 800-mesh flaky zinc powder, 3.0 to 7.0 percent of filler, 0.1 to 0.5 percent of dispersant, 0.1 to 0.5 percent of defoamer, 2.4 to 3.6 percent of anti-settling agent and 1.6 to 5.0 percent of other components; wherein the sum of the weight percentages of the A components is one hundred percent; the component B comprises 93.0 to 97.0 percent of epoxy emulsion, 1.0 to 3.0 percent of flash rust inhibitor, 0.3 to 0.7 percent of thickener and 1.5 to 3.5 percent of water; wherein the sum of the weight percentages of the B components is one hundred percent. The water-based epoxy zinc-rich primer product has good initial water resistance, outstanding flash rust resistance and excellent salt spray resistance, and can be widely applied to primer coating of the surface of a metal substrate in the field of industrial corrosion prevention.

Description

A kind of high-resistance waterborne epoxy zinc-rich primer and preparation method thereof

technical field

The invention belongs to the technical field of water-based anticorrosion coatings, and in particular relates to a high-resistance water-based epoxy zinc-rich primer and a preparation method thereof.

Background technique

Zinc-rich primers can be divided into three types according to their film-forming substances: inorganic, organic, and organic/inorganic blends. Inorganic zinc-rich primers can be divided into water glass, ethyl silicate and phosphate according to the film-forming substances, among which ethyl orthosilicate is the most widely used at home and abroad. Epoxy, chlorinated rubber, vinyl resin and polyurethane resin are commonly used as film-forming base materials for organic zinc-rich primers, and epoxy zinc-rich primers are most commonly used.

Epoxy zinc-rich primer is widely used in the anti-corrosion field of steel, especially in the field of heavy-duty anti-corrosion due to its dual anti-corrosion mechanism of "physical shielding" and "anode sacrifice". However, solvent-based epoxy zinc-rich primer is still widely used at present. Primer. Due to its high VOCs content, solvent-based coatings have caused great harm to the environment and construction personnel, and cannot meet the needs of sustainable development. Waterborne epoxy zinc-rich primer has been widely used and researched as an environmentally friendly coating, but there is still a lot of controversy in the industry about the performance of waterborne epoxy zinc-rich primer. It is believed that the performance of waterborne epoxy zinc-rich primer is not as good as that of solvents Many people even think that it is difficult to apply in the field of heavy anti-corrosion, especially when the corrosion environment is C5 and above, it is difficult to meet the requirements. The resistance of water-based coatings is an important index to measure whether it can be applied in the field of heavy-duty anti-corrosion. Due to its special film-forming process and solvent system, compared with solvent-based coatings, some special resistances, especially initial water resistance and flash resistance Rust resistance and salt spray resistance are particularly important.

In terms of improving the anti-corrosion performance of water-based coatings, many current studies focus on using carbon nanomaterials, such as graphene and carbon nanotubes, to modify epoxy zinc-rich primers to improve their anti-corrosion properties. The nanostructure and high conductivity of carbon nanomaterials are used to improve the shielding and cathodic protection of epoxy zinc-rich primers to improve its anti-corrosion performance, but less attention is paid to some properties required in its actual application process, such as initial water resistance, Flash rust resistance, and these properties are often the key properties that determine whether the waterborne epoxy zinc-rich primer can be successfully applied to the heavy-duty anti-corrosion field.

The Chinese patent document with application number 201711177381.0 discloses a long-acting waterborne epoxy zinc-rich anti-corrosion primer and its coating method. The product has a simple construction process and good anti-corrosion durability, but the performance and technical solution of the product in terms of initial water resistance and flash rust resistance are not mentioned in the patent application; the Chinese patent document with the application number 201810214574.7 discloses a water-based ring Oxygen-rich zinc primer and its preparation method, the product has excellent anti-sagging performance and good anti-settling performance, which improves the storage performance of the coating, but the patent application does not mention the product's initial water resistance and flash rust resistance. Performance and technical solutions, and the salt spray resistance time is only 1000h, which does not show the excellence and long-term effect of its anti-corrosion performance.

The present invention is made based on this situation.

Contents of the invention

The purpose of the present invention aims at the deficiencies in the initial water resistance, flash rust resistance and salt spray resistance in the existing water-based epoxy zinc-rich primer technology, and provides a high-resistant water-based epoxy zinc-rich primer. The water-based epoxy zinc-rich primer product has good initial water resistance, outstanding flash rust resistance, excellent salt spray resistance, good storage stability, strong adhesion, fast drying speed, low VOC content, health and environmental protection, and convenient construction. Widely used in the primer coating on the surface of metal substrates in the field of industrial anticorrosion. Another object of the present invention is to provide a preparation method of the high resistance waterborne epoxy zinc-rich primer.

In order to achieve the above object, the present invention takes the following technical solutions:

A high-resistance water-based epoxy zinc-rich primer, consisting of the following components A and B by weight:

A component

Wherein the weight percentage sum of each component in A component is 100%;

B component

Wherein the sum of the weight percentages of each component in the B component is 100%.

In the present invention, the modified alicyclic amine water-based curing agent and the modified polyamide water-based curing agent in the A component are water-based amine epoxy curing agents. The weight ratio of the modified alicyclic amine water-based curing agent to the modified polyamide water-based curing agent is (1.2-1.3):1.

The cycloaliphatic curing agent has proper pot life, good bonding performance, high gloss, low color, good chemical resistance and high hardness, but poor flexibility, which is not conducive to improving the impact resistance of the coating. The amide curing agent paint has good adhesion, good flexibility, long pot life and no irritating smell, but its reaction speed is slightly low and the hardness is not good. The high-resistance water-based epoxy zinc-rich primer of the present invention is selected from modified alicyclic amine water-based curing agent and modified polyamide water-based curing agent according to a certain weight ratio, and the paint film has better chemical resistance and higher Hardness and impact resistance, fast drying speed, good anti-corrosion performance.

In the present invention, the film-forming aid in the A component is formed by mixing propylene glycol butyl ether and propylene glycol methyl ether acetate in a weight ratio (1.5-2.5):1.

In the present invention, the zinc powder in the A component adopts 500 mesh spherical zinc powder and 800 mesh flake zinc powder. The weight ratio of the 500-mesh spherical zinc powder to the 800-mesh flake zinc powder is (0.4-0.8):1.

Flake zinc powder has the advantages of strong shielding effect, good anti-sedimentation property, and less amount of zinc powder, but the flake zinc powder is not easy to disperse; Powder is easier to disperse. In the case of the same paint film thickness and a certain amount of total zinc powder, as the weight ratio of spherical zinc powder to flake zinc powder increases, water, oxygen, and ions are more likely to diffuse in the coating, and the shielding effect is relatively poor. The anti-corrosion performance is relatively poor. Conversely, as the weight ratio of spherical zinc powder and flake zinc powder decreases, the content of flake zinc powder increases relatively. Under the same paint film thickness, spherical zinc powder has only a few layers, while flake zinc powder can reach hundreds of layers. Layers, forming a system of parallel overlapping and overlapping arrangements in the coating, thereby reducing the porosity of the coating, improving the shielding performance of the coating, and significantly reducing the diffusion of water, oxygen, and ions in the coating. Corrosion resistance is greatly improved. However, when the ratio of spherical zinc powder to flake zinc powder is reduced to a certain weight ratio, the pigment is basically flake zinc powder, and the flake structure reduces the diffusion of water, oxygen, and ions in the coating, and the performance The water resistance becomes better gradually, but the failure rate of flake zinc powder is faster than that of spherical zinc powder, so the salt water resistance and salt spray resistance become worse. Considering the above reasons, in order to further improve the high resistance of the water-based zinc-rich primer, the ratio of spherical zinc powder to flake zinc powder is determined to be (0.4-0.8):1.

In the present invention, the total weight percentage of the 500-mesh spherical zinc powder and the 800-mesh flaky zinc powder in the formula in the A component is 65%-85%.

Zinc powder is an active pigment with good rust resistance and atmospheric corrosion resistance, which can protect steel structures. The reason is that the electrode potential of zinc is -0.7628V, and that of iron is -0.409V. After moisture invades the coating film, zinc powder and steel form a micro battery. Since the electrode potential of zinc is lower than that of iron, the corrosion current flows from zinc to iron at this time, and the steel is protected by cathodic protection. At the same time, the zinc salt produced by the corrosion of zinc powder can fill the pores of the coating film, seal the damaged part of the coating, protect the zinc particles in the lower layer, delay its corrosion, and then protect the steel surface. With the increase of zinc content, the salt water resistance and salt spray resistance of the paint film are obviously improved, but the adhesion of the paint film is decreased. This is because as the amount of zinc powder increases, the resin content in the zinc-rich primer decreases, and the film-forming substances decrease relatively. When a certain critical point is reached, the resin in the zinc-rich primer is not enough to cover all the zinc powder. , so that a continuous and dense coating film cannot be formed, resulting in changes in various properties of the coating film. If the adhesion and shielding effect of the paint film are weakened, the corrosive medium will directly penetrate into the surface of the zinc powder, causing the zinc powder to corrode, and the volume of the zinc powder particles will increase, thereby increasing the possibility of coating blisters. The corrosive medium invades the interior of the coating and causes the surface of the substrate to corrode, resulting in the peeling off of the paint film. According to the experimental research results of the present invention, when the total content of zinc powder in the formula exceeds 85%, various properties of the paint film are all reduced. Considering comprehensively, the total weight percentage of spherical zinc powder and flake zinc powder in the formula of the present invention is 65%-85%.

In the present invention, the filler in the A component is 1250 mesh talcum powder.

In the present invention, the dispersant in the A component is a high-molecular polymer dispersant. In the present invention, the high-molecular-weight dispersant AdditoL VXW 6208/60 from Allnex is preferred.

This patent studies the influence of high molecular polymer type, polycarboxylate type and organic phosphate type dispersant on coating film tolerance. When the high molecular polymer dispersant is used, the comprehensive resistance of the coating film is the best, and its initial water resistance is not less than 480h, which is about 10 times that of the polycarboxylate dispersant and 2.9 times that of the organic phosphate dispersant; The salt spray resistance of the film is 3000h without blistering or rusting, which is about 7.5 times that of polycarboxylate-type dispersants and 5 times that of organic phosphate-type dispersants. This is because the high molecular polymer dispersant itself has better water resistance, and its compatibility with epoxy resin and amine curing agent is better, and it has excellent water resistance while having dispersing performance.

In the present invention, the defoamer in the A component is TEGO FOAMEX 810.

In the present invention, the anti-settling agent in the A component is compounded by anti-settling agent 1, anti-settling agent 2, and anti-settling agent 3 according to the weight percentage of (1.0～1.5):(1.2～1.8):1 made.

Further, the anti-settling agent 1 is attapulgite provided by Zhongshan Yongfeng Chemical Co., Ltd., the anti-settling agent 2 is BENTONE EW NA bentonite provided by ELEMENTIS, and the anti-settling agent 3 is Cabot Provided with fumed silica M-5.

Although a single anti-settling agent (attapulgite, bentonite, fumed silica) can improve the anti-settling and anti-sagging properties of two-component waterborne epoxy zinc-rich coatings to a certain extent, the effect is not obvious. However, when three kinds of thixotropic agents, attapulgite, bentonite and fumed silica, are compounded by weight percentage (1.0～1.5):(1.2～1.8):1, it can effectively solve the problem of waterborne epoxy zinc-rich primer. Anti-sinking and anti-sagging problems. The main reason is: the layer chain structure of attapulgite clay, the layer structure of bentonite, and the network structure (three-dimensional) of fumed silicon can play a very good synergistic effect, thus playing a good role in the coating system. Anti-settling and anti-sagging effect.

In the present invention, the epoxy emulsion in the B component is the epoxy resin BECKOPOX ^TM EP384w provided by allnex.

In the present invention, the anti-flash rust agent in the B component is the anti-flash rust agent FA-179 provided by Hemings (Deqian).

In the present invention, the thickener in the B component is polyurethane thickener SN612 provided by Guangzhou Guanzhi Chemical Co., Ltd.

The present invention also provides a preparation method of the high-resistance water-based epoxy zinc-rich primer, the specific steps are as follows:

(1) Preparation of component A: add modified alicyclic amine water-based curing agent, modified polyamide water-based curing agent, film-forming aid, 500-mesh spherical zinc powder, and 800-mesh flake into the dispersion tank according to the formula amount Zinc powder, filler, dispersant, defoamer, anti-sedimentation agent and other components, disperse at a speed of 1200-1500r/min until the finished product has a fineness of ≤50um and a viscosity of 100-150s;

(2) Preparation of component B: add epoxy emulsion, anti-flash rust agent, thickener and water in the dispersion tank according to the formula, disperse at a speed of 800-1000r/min for 20-30min, filter and pack;

(3) Mix component A and component B according to the weight ratio of 3:1, and let it stand for a while.

Compared with prior art, the beneficial effect of the present invention is:

1) The volatile organic compound (VOC) content of the product of the present invention is effectively controlled within 50g/L", which is far lower than that in the chemical industry standard of the People's Republic of China "HG/T 5176-2017 "Water-based Anticorrosion Coatings for Steel Structures"" The VOC content limit of the water-based zinc-rich primer is 200g/L, which is a truly healthy and environmentally friendly water-based paint product.

2) The drying speed of the product is fast; the surface dry time is ≤0.6h, and the hard drying time is ≤9.2h, which is far less than the water-based zinc-rich primer in the chemical industry standard of the People's Republic of China "HG/T 5176-2017 "Water-based Anticorrosion Coatings for Steel Structures"" The surface drying time (4h) and solid drying time (24h) of the paint realize the characteristics of quick drying of the product.

3) Good freeze-thaw stability and storage stability, excellent anti-sag performance, good anti-settling effect, easy construction, and convenient operation; the product paint film has strong adhesion to the substrate and good impact resistance;

4) The product has extremely high resistance, which is manifested in initial water resistance, flash rust resistance and salt spray resistance; the product has excellent initial water resistance, and the initial water resistance time is far beyond the industry standard and the initial water resistance time of similar products in the industry (24h), reaching more than 480h; the product has outstanding flash rust resistance. According to the conditions stipulated in GB/T 9278-2008, after 24 hours of maintenance, the test shows whether there is penetrating rust on the surface of the coating film, and there is no rust on the substrate ;The salt spray resistance of the product is excellent, and the salt spray resistance time is far beyond the industry standard and the salt spray resistance time (600h) of similar products in the industry, reaching more than 2400h, no blistering, no rust.

Detailed ways

In this embodiment, a high-resistance water-based epoxy zinc-rich primer consists of the following components A and B by weight:

A component

Wherein the weight percentage sum of each component in A component is 100%;

B component

Wherein the weight percentage sum of each component in the B component is 100%.

The film-forming aid in the A component is a mixture of propylene glycol butyl ether and propylene glycol methyl ether acetate in a weight ratio (2.0-4.0): (1.0-3.0); the dispersant is Allnex’s high molecular weight dispersant AdditoL VXW 6208/60; the defoamer is TEGO FOAMEX 810; the anti-settling agent is anti-settling agent 1, anti-settling agent 2, anti-settling agent 3 according to (0.8～1.2):(1.0～1.4 ): (0.6～1.0) by weight percentage, the anti-settling agent 1 is attapulgite provided by Zhongshan Yongfeng Chemical Co., Ltd., and the anti-settling agent 2 is BENTONE EW NA provided by ELEMENTIS Bentonite, the anti-settling agent 3 is fumed silica M-5 provided by Cabot.

The epoxy emulsion in the B component is the epoxy resin BECKOPOX ^TM EP 384w provided by Allnex; the anti-flash rust agent is the anti-flash rust agent FA-179 provided by Hemings (Deqian); the The thickener is polyurethane thickener SN612 provided by Guangzhou Guanzhi Chemical Co., Ltd.

The preparation method of the high resistance water-based epoxy zinc-rich primer described in the present embodiment, the concrete steps are as follows:

(1) Preparation of component A:

Add modified alicyclic amine water-based curing agent, modified polyamide water-based curing agent, film-forming aid, 500 mesh spherical zinc powder, 800 mesh flake zinc powder, filler (talcum powder), Dispersant, defoamer, anti-sedimentation agent and other components are dispersed at high speed for 30-50 minutes, and the speed of high-speed dispersion is 1200-1500r/min. Sampling to test the fineness and viscosity of the finished product. If the fineness of the finished product reaches ≤50um and the viscosity is 100-150s, component A is obtained.

(2) Preparation of component B:

Add epoxy emulsion, anti-flash rust agent, thickener and water into the dispersion tank by weight percentage, disperse at a medium speed for 20-30 minutes, and the medium-speed dispersion speed is 800-1000r/min. Filter packs.

(3) Mix component A and component B according to the weight ratio of 3:1, and let it stand for 15 minutes.

The present invention will be further described below in conjunction with specific examples, but is not limited thereto.

In this specific example, embodiments 1 to 5 are set to prepare the high-resistance water-based epoxy zinc-rich primer of the present invention, wherein the formulas of A and B components are shown in Table 1, and the formula composition is based on raw material mass percentage (% )count:

The formula (unit: %) of high resistance waterborne epoxy zinc-rich primer of table 1

According to the raw material formula in the above table embodiment 1～5, and according to the preparation method of above-mentioned high resistance waterborne epoxy zinc-rich primer, the product of the high-resistant waterborne epoxy zinc-rich primer of embodiment 1～5 is prepared, and make Performance Testing.

Performance Testing

The products of the highly resistant water-based epoxy zinc-rich primers prepared in Examples 1-5 of the present invention were sprayed and tested with similar commercially available products.

According to the standards of "HG/T 5176-2017 "Water-based Anticorrosion Coatings for Steel Structures"" and "HJ 2537-2014 Environmental Labeling Product Technical Requirements Water-based Coatings" standards, the main performance test is carried out; other basic performance tests are in accordance with HG/T3668-2009 regulations method is carried out.

Initial water resistance test. According to the conditions specified in GB/T 9278-2008, test after curing for 24 hours; immerse half of the coating of the test panel in pure water for a certain period of time, and then take out the test panel for visual observation. If there is no blistering, rust, If there are pathological phenomena of the coating film such as cracking and peeling, and after the test panel is recovered for 2 hours under standard conditions, no obvious discoloration is observed in the soaked area compared with the unsoaked area, then it is considered "normal".

Flash rust resistance performance test. According to the conditions specified in GB/T 9278-2008, test after 24 hours of curing, visually observe whether there is penetrating corrosion on the surface of the coating film; immediately after that, soak the test panel in methyl ethyl ketone solvent, remove the coating film, and visually observe the corrosion on the substrate. There are no rust spots. Visually observe that there is no rust on the surface of the coating film and no rust spots on the substrate, then it is evaluated as "normal", otherwise it is "unqualified".

The products prepared in the above Examples 1-5 and the commercially available similar products, the test results of the main performance indicators are shown in Table 2.

Table 2 Test results

According to the test results in Table 2, it can be seen that the content of volatile organic compounds (VOC) in the highly resistant waterborne epoxy zinc-rich primer prepared in Examples 1 to 5 is effectively controlled within 50g/L, which is far lower than that of the People's Republic of China The VOC content limit of the water-based zinc-rich primer in the chemical industry standard "HG/T 5176-2017 "Water-based anti-corrosion coatings for steel structures" is 200g/L, which is a truly healthy and environmentally friendly water-based coating product. The product dries quickly. Table Drying time ≤ 0.6h, hard drying time ≤ 9.2h, far less than the surface drying time (4h) of water-based zinc-rich primer in the chemical industry standard of the People's Republic of China "HG/T 5176-2017 "Water-based Anticorrosion Coatings for Steel Structures"" And hard drying time (24h), realize the characteristics of fast drying of the product. The product has good freeze-thaw stability and storage stability, excellent anti-sagging performance, good anti-settling effect and easy construction, and easy to operate. The product The paint film has strong adhesion to the substrate and good impact resistance. It is especially worth mentioning that the product of the present invention has extremely high resistance, which is embodied in initial water resistance, flash rust resistance and salt spray resistance. The product The initial water resistance is excellent, the initial water resistance time is far longer than the industry standard and the initial water resistance time (24h) of similar products in the industry, and the initial water resistance has reached more than 480h. The product has outstanding flash rust resistance, in accordance with the provisions of GB/T 9278-2008 Tested after 24 hours of maintenance under certain conditions, whether there is penetrating corrosion on the surface of the coating film, and no rust spots on the substrate. The product has excellent salt spray resistance, and the salt spray resistance time is far longer than the industry standard and the salt resistance of similar products in the industry The fog time (600h) has reached more than 2400h, without blistering or rusting.

The above-mentioned preferred implementation mode should be regarded as an illustration of the implementation mode of the application scheme, and any technical deduction, replacement, improvement, etc. that are identical, similar to or based on the application scheme should be regarded as the protection scope of the present invention.

Claims (10)

1. A high-resistance water-based epoxy zinc-rich primer is characterized in that it is composed of the A component and the B component of the following percentage by weight: A component

Wherein the weight percentage sum of each component in A component is 100%; B component

Wherein the sum of the weight percentages of each component in the B component is 100%. 2. high resistance water-based epoxy zinc-rich primer according to claim 1, is characterized in that: in the described A component, the weight ratio of modified alicyclic amine water-based curing agent, modified polyamide water-based curing agent is ( 1.2～1.3):1. 3. high resistance water-based epoxy zinc-rich primer according to claim 1, is characterized in that: the film-forming aid in the described A component is by weight ratio (1.5～ 2.5): 1 mixed. 4. The high-resistance water-based epoxy zinc-rich primer according to claim 1, characterized in that: the weight ratio of 500 mesh spherical zinc powder to 800 mesh flake zinc powder in the A component is (0.4～0.8) :1. 5. the high-resistance water-based epoxy zinc-rich primer according to claim 1, is characterized in that: the filler in the described A component is 1250 purpose talcum powder; The dispersant is a high molecular polymer type dispersant; The defoamer in the A component is TEGOFOAMEX 810. 6. The high-resistance water-based epoxy zinc-rich primer according to claim 5, characterized in that: the polymer-based dispersant is selected from Allnex's high-molecular-weight dispersant AdditoL VXW 6208/60. 7. high resistance water-based epoxy zinc-rich primer according to claim 1, is characterized in that: the anti-settling agent in the described A component is by anti-settling agent 1, anti-settling agent 2, anti-settling agent 3 by ( 1.0～1.5):(1.2～1.8):1 The weight ratio is compounded. 8. The high-resistance water-based epoxy zinc-rich primer according to claim 7, characterized in that: the anti-settling agent 1 is attapulgite provided by Zhongshan Yongfeng Chemical Co., Ltd.; the anti-settling agent 2 BENTONE EWNA bentonite provided by ELEMENTIS was selected; the anti-settling agent 3 was fumed silica M-5 provided by Cabot. 9. The high-resistance water-based epoxy zinc-rich primer according to claim 1, characterized in that: the epoxy emulsion in the B component is the epoxy resin BECKOPOX ^TM EP 384w provided by Allnex, which is anti-flash rust The anti-flash rust agent FA-179 provided by Hemings (Deqian) was used as the agent, and the polyurethane thickener SN612 provided by Guangzhou Guanzhi Chemical Co., Ltd. was used as the thickener. 10. a preparation method of the high-durability water-based epoxy zinc-rich primer described in any one of claims 1-9, is characterized in that comprising the following steps: (1) Preparation of component A: add modified alicyclic amine water-based curing agent, modified polyamide water-based curing agent, film-forming aid, 500-mesh spherical zinc powder, and 800-mesh flake into the dispersion tank according to the formula amount Zinc powder, filler, dispersant, defoamer, anti-sedimentation agent and other components are dispersed at a speed of 1200-1500r/min until the finished product has a fineness of ≤50um and a viscosity of 100-150s; (2) Preparation of component B: add epoxy emulsion, anti-flash rust agent, thickener and water in the dispersion tank according to the formula, disperse at a speed of 800-1000r/min for 20-30min, filter and pack; (3) Mix component A and component B according to the weight ratio of 3:1, and let it stand for a while.