A chlorinated rubber topcoat and preparation method thereof

Abstract

The invention discloses a chlorinated rubber topcoat and a preparation method thereof. The chlorinated rubber topcoat of the invention is prepared from chlorinated rubber, alkyd resin, bisphenol A epoxy resin, stabilizer, toughening agent, solvent, defoamer, wetting dispersant, rheology control additive, pigment and filler, the oil content of the alkyd resin is 60-70%, and the epoxy equivalent of the bisphenol A epoxy resin is 180-210 g / mol. The invention can improve the flexibility, impact resistance, adhesion, corrosion resistance, weather resistance and glossiness of the chlorinated rubber topcoat, and is suitable for long-term protection of parts above the waterline of ships, bridges, chemical equipment, steel structures, etc.

Description

Technical Field

[0001] This invention belongs to the field of coatings, and particularly relates to a chlorinated rubber topcoat and its preparation method. Background Art

[0002] For surface protection of parts of ships above the waterline, bridges, chemical equipment, steel structures, etc., polyurethane paint, epoxy paint, chlorinated rubber paint, etc. are commonly used. Among them, chlorinated rubber topcoat is a single-component coating and is widely used due to its storage stability, convenient construction and good recoatability. However, chlorinated rubber topcoat still has some shortcomings in practical applications, such as low gloss, poor adhesion, corrosion resistance and weather resistance. When exposed to harsh environments for a long time, it is prone to discoloration and cannot effectively resist the erosion of seawater, salt spray and ultraviolet rays. In addition, it has poor flexibility, especially with a high construction film thickness, the flexibility and impact resistance are significantly reduced.

[0003] Patent CN113881267A improves the adhesion and water resistance of chlorinated rubber anticorrosive paint by grafting acrylate monomers with hydrophilic groups into chlorinated rubber and controlling the mass ratio of chlorinated rubber, acrylate monomers, and thickener to 1:0.2~0.5:0.1~0.3. Patent CN109161316A improves adhesion by using an alkyd resin made from specific components such as soybean oil, lithium hydroxide, pentaerythritol, benzoic acid, phthalic anhydride, tung oil, xylene, and butyl acetate, as well as a specific 5130PP adhesion promoter. However, none of the above patents improve the flexibility and weather resistance of chlorinated rubber paint.

[0004] Therefore, there is an urgent need to develop a high-adhesion chlorinated rubber topcoat that can enhance the flexibility and impact resistance of the paint film, as well as improve its corrosion resistance, weather resistance, and gloss, thereby extending the life of the paint film and achieving long-term protection. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a chlorinated rubber topcoat and its preparation method. The chlorinated rubber topcoat of this invention is prepared from chlorinated rubber, alkyd resin, bisphenol A type epoxy resin, stabilizer, toughening agent, solvent, defoamer, wetting and dispersing agent, rheology control agent, pigment, and filler. The alkyd resin has an oil content of 60-70%, and the bisphenol A type epoxy resin has an epoxy equivalent of 180-210 g / mol. This improves the flexibility, impact resistance, adhesion, corrosion resistance, weather resistance, and gloss of the chlorinated rubber topcoat, making it suitable for long-term protection of ship above-water sections, bridges, chemical equipment, steel structures, etc.

[0006] The technical solution of the present invention is: a chlorinated rubber topcoat, characterized in that it is compounded from the following components in parts by weight: 15-20 parts chlorinated rubber, 10-15 parts alkyd resin, 0.3-5 parts bisphenol A epoxy resin, 3-6 parts toughening agent, 15-25 parts solvent, 0.1-0.4 parts defoamer, 0.5-0.8 parts wetting and dispersing agent, 2-5 parts rheology control agent, 20-25 parts pigment, 10-15 parts filler, and 0.5-3 parts stabilizer.

[0007] Preferably, the chlorinated rubber has a chlorine content of 64-68%. The introduction of chlorine atoms into the chlorinated rubber helps improve the performance of the coating. The increase in chlorine content leads to more saturated bonds in the chlorinated rubber molecular structure, which can enhance the rigidity and density of the molecular chains in the chlorinated rubber molecular structure, improve the saturation and stability of the chlorinated rubber molecules, and help enhance the corrosion resistance, weather resistance, adhesion between the topcoat and the substrate, the deformation resistance of the coating, and balance the hardness and toughness of the resin molecules. In the embodiments of the present invention, the chlorinated rubber used is further selected from one or more of S-20, CRF10, CRF20, CR-10, or CR-20.

[0008] Preferably, the alkyd resin is a long-oil alkyd resin with an oil content of 60-70%. Alkyd resins have high gloss, and through synergy with bisphenol A type epoxy resin and chlorinated rubber, the coating surface becomes smoother and more delicate, thereby improving the gloss of the coating and enhancing its decorative effect. In the embodiments of this invention, the alkyd resin is further selected from one or more of QT-6380, 389-9B, GL3303, and RV8111.

[0009] Preferably, the epoxy equivalent of the bisphenol A epoxy resin is 180~210 g / mol. Based on the chlorinated rubber topcoat provided by the present invention, a specific epoxy equivalent helps to enhance the crosslinking density of the bisphenol A epoxy resin, alkyd resin, and chlorinated rubber, thereby enhancing the adhesion, corrosion resistance, weather resistance, and stability of the coating film. A decrease in the epoxy equivalent of the bisphenol A epoxy resin leads to excessively fast curing, generating shrinkage stress and affecting the smoothness and adhesion of the coating. Conversely, an excessively high epoxy equivalent results in a low degree of crosslinking participation by the bisphenol A epoxy resin, failing to improve adhesion, corrosion resistance, and weather resistance. In the embodiments of the present invention, the bisphenol A epoxy resin is further selected from one or more of E-51, E-55, Epon Resin 828 (Epon 828), and DER331.

[0010] Preferably, the stabilizer is a compound of zinc oxide and bisphenol A polyoxyethylene ether (BPE) in a mass ratio of 3 to 5:1. The bisphenol A polyoxyethylene ether used in the embodiments of the present invention is selected from one or both of BPE-6 and BPE-10.

[0011] Preferably, the toughening agent is a compound of 52# chlorinated paraffin and polyvinyl acetate (PVAc), with a mass ratio of 2 to 5:1. The polyvinyl acetate used in the embodiments of the present invention is selected from one or more of PVAc 234K, PVAc 195K, or PVAc 189K.

[0012] Preferably, the wetting and dispersing agent is a high molecular weight modified polyurethane dispersant, and in the embodiments of the present invention, it is selected from one or more of EFKA4063, Anjeka-6161A, and BYK-163.

[0013] Preferably, the defoamer is a fluorinated modified defoaming polysiloxane solution, and in the embodiments of the present invention, it is selected from one or more of BYK-066N, BYK-065 or NEO-5608.

[0014] Preferably, the rheology control agent is a compound of organically modified bentonite and polyamide wax powder, with a mass ratio of 1:1 to 4. In this embodiment of the invention, the organically modified bentonite is selected from one or more of Bentone 828, Bentone SD-2, Bentone 27, or Bentone 34, and the polyamide wax powder is selected from one or more of SUPER, RC-800, MT6650, and PA-8600.

[0015] Preferably, the pigment is selected from one or more of titanium dioxide, phthalocyanine pigment (phthalocyanine blue or phthalocyanine green), or iron oxide pigment (iron oxide red, iron oxide yellow, or iron oxide black); the filler is selected from one or more of mica powder, talc powder, and graphite powder; and the solvent is one or more of xylene, butyl acetate, propylene glycol methyl ether acetate, and heavy aromatic hydrocarbons.

[0016] This invention also provides a method for preparing a chlorinated rubber topcoat, comprising the following steps:

[0017] S1: Add solvent, alkyd resin, bisphenol A epoxy resin, toughening agent, defoamer, and wetting and dispersing agent to a dispersion tank, adjust the rotation speed to 800~1500 r / min, and stir for 10~20 min;

[0018] S2: Add rheology control agent, filler, pigment and stabilizer, stir evenly and then transfer to a grinder for grinding until the fineness is <40µm to form a slurry;

[0019] S3: Add the slurry and chlorinated rubber to the dispersion tank, adjust the rotation speed to 800~1000r / min, stir for 15~20min, adjust the viscosity to 100~110KU, and filter to obtain chlorinated rubber topcoat.

[0020] Chlorinated rubber, as the main film-forming substance of chlorinated rubber topcoat, endows the topcoat with certain water resistance, chemical resistance, mildew resistance, abrasion resistance, and scratch resistance. However, the paint film is hard and brittle, and sensitive to temperature, organic solvents, and oils. The gloss, solid content, flexibility, impact resistance, weather resistance, and corrosion resistance of the topcoat are relatively low, resulting in poor decorative properties and easy fading, which increases the difficulty and cost of construction.

[0021] To address the aforementioned problems, this invention employs a compound of alkyd resin, bisphenol A epoxy resin, and chlorinated rubber. Through a synergistic effect, the flexibility and impact resistance of the chlorinated rubber topcoat are improved, as well as the overall weather resistance and corrosion resistance of the coating. This enhances its resistance to the erosion of acids, alkalis, salts, and other chemicals, strengthens its resistance to natural factors such as ultraviolet radiation and weathering, and extends the service life of the coating. Both alkyd resin and bisphenol A epoxy resin contain polar functional groups in their molecular structures. When compounded with chlorinated rubber, these functional groups can form chemical bonds with polar groups on the surfaces of various substrates such as metals and concrete, thereby enhancing the adhesion between the coating and the substrate.

[0022] Other raw materials and their uses:

[0023] Stabilizer: Zinc oxide compounded with bisphenol A polyoxyethylene ether. Chlorinated rubber is a highly chlorinated polymer containing a large number of chlorine atoms and active groups in its molecules. During storage and curing, chlorinated rubber topcoats, under the influence of high temperatures and moisture, generate HCl, which forms double bonds in the molecules, causing cross-linking and releasing heat, thus increasing the temperature and viscosity of the paint film until it gels. Zinc oxide is commonly used as a stabilizer for chlorinated rubber topcoats; however, due to its strong polarity and high surface energy, zinc oxide is not easily dispersed uniformly, which can easily lead to unstable performance in local areas, resulting in particle agglomeration and precipitation, affecting the adhesion and corrosion resistance of the paint film. After introducing bisphenol A polyoxyethylene ether, the longer polyoxyethylene chains in its molecular structure fully extend and surround the zinc oxide particles in the system, preventing the zinc oxide particles from approaching each other and agglomerating. Furthermore, the hydrophilic oxyethylene ether segments and hydrophobic bisphenol A groups contained in bisphenol A polyoxyethylene ether improve the surface properties of zinc oxide and the surface tension of the chlorinated rubber topcoat, making it easier for the system to encapsulate and disperse the zinc oxide particles, reducing the tendency of zinc oxide particles to aggregate, and ensuring that zinc oxide remains dispersed in the chlorinated rubber topcoat. Furthermore, based on the chlorinated rubber topcoat provided by this invention, the addition of bisphenol A polyoxyethylene ether enhances the adhesion between the chlorinated rubber topcoat and the substrate by forming strong chemical bonds with the substrate surface. Bisphenol A polyoxyethylene ether has good compatibility with chlorinated rubber and, by participating in the film-forming process, can fill the gaps between chlorinated rubber molecules, making the formed paint film more uniform and dense, and improving the mechanical strength, weather resistance, and chemical corrosion resistance of the paint film. When used for surface protection of facilities such as ships and bridges that are exposed to harsh environments for a long time, it can effectively resist the erosion of seawater, salt spray, and ultraviolet rays.

[0024] Toughening Agent: 52# chlorinated paraffin, as a toughening agent, can insert into the molecular chains of chlorinated rubber, increasing the distance between the chains and reducing the intermolecular forces, making the chlorinated rubber molecular chains easier to move. This improves the flexibility and tensile strength of the topcoat. However, at high film thicknesses, the intermolecular movement slows down, hardness increases, and flexibility is difficult to maintain, making it prone to brittleness and cracking. The toughening agent of this invention incorporates polyvinyl acetate, which can effectively disperse the stress generated in the coating and improve the toughness of the paint. Working synergistically with 52# chlorinated paraffin, when the topcoat is impacted, the flexibility of 52# chlorinated paraffin can absorb some of the impact energy, while the plasticizing effect of polyvinyl acetate allows the topcoat to better disperse and transfer impact stress, preventing stress concentration that could lead to cracking or damage. This improves the flexibility of the chlorinated rubber topcoat, maintaining excellent flexibility even at higher film thicknesses, improving the impact resistance and crack resistance of the paint film, and making it less prone to brittleness and cracking. Polyvinyl acetate has strong adhesion and film-forming properties. When combined with 52# chlorinated paraffin, it further enhances the adhesion between the coating and the substrate, improves the anti-sagging properties, and together improves the coating's workability, film uniformity, stability and density. It also effectively avoids sedimentation and delamination, and further enhances the film's aging resistance.

[0025] Wetting and dispersing agent: This is a high molecular weight modified polyurethane dispersant, which exhibits excellent wetting and flow properties in the system of this invention. It significantly improves the wetting performance of the coating on the substrate surface, helps the coating spread better on the substrate surface, reduces the generation of defects such as bubbles and pinholes, prevents flocculation and sedimentation through steric hindrance, effectively reduces the viscosity of the coating, ensures uniform dispersion of pigments in the coating system, improves the hiding power, tinting strength and gloss of the coating, and reduces problems such as floating color and blooming. In addition, the high molecular weight modified polyurethane dispersant has a long molecular chain, which entangles and interweaves during the curing process of the chlorinated rubber topcoat provided by this invention, forming a network structure, which enhances the strength and toughness of the paint film. It also further enhances the adhesion between the coating and the substrate by penetrating into the micropores and cracks on the substrate surface.

[0026] Defoamer: This is a fluorinated modified defoaming polysiloxane solution. The fluorine groups in the fluorinated modified defoaming polysiloxane solution form a low-energy protective film on the molecular surface, which reduces the surface tension of the fluorinated modified polysiloxane solution, improves the wettability of the substrate, and can quickly penetrate into the foam and disrupt its stability, causing the foam to dissipate rapidly, thereby improving the smoothness and gloss of the coating. In the chlorinated rubber topcoat provided by this invention, the fluorinated modified defoaming polysiloxane solution enhances the chemical stability and durability of the coating, reducing coating degradation and failure caused by environmental factors.

[0027] Rheology control additive: This is a compound of organically modified bentonite and polyamide wax powder. Organically modified bentonite exhibits excellent dispersibility and anti-settling properties in coatings, effectively preventing sagging during the application of chlorinated rubber topcoats. The compounding of organically modified bentonite with polyamide wax powder further enhances the thixotropic and anti-sagging properties of chlorinated rubber topcoats, reducing sagging and dripping, while also improving workability and film-forming properties, and balancing the effects on gloss and adhesion.

[0028] Fillers: All fillers in this invention are sheet fillers. The sheet fillers form a tight shielding layer in the coating, which effectively prevents the penetration of moisture, oxygen and corrosive media, improves the anti-corrosion performance of the coating, enhances the overall adhesion of the coating, and improves the hardness and wear resistance of the coating.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention employs a compound of alkyd resin, bisphenol A epoxy resin, and chlorinated rubber. Through a synergistic effect, it enhances the flexibility, impact resistance, weather resistance, and corrosion resistance of the chlorinated rubber topcoat, extending the coating's service life. Both alkyd resin and bisphenol A epoxy resin contain polar functional groups in their molecular structures. After compounding with chlorinated rubber, these functional groups can form chemical bonds with polar groups on the surfaces of various substrates such as metals and concrete, thereby enhancing the adhesion between the coating and the substrate. Experiments have shown that compounding alkyd resin with an oil content of 60-70%, bisphenol A epoxy resin with an epoxy equivalent of 180-210 g / mol, and chlorinated rubber significantly improves the gloss and flexibility of the paint film, and enhances its adhesion, mechanical strength, weather resistance, and chemical corrosion resistance.

[0031] 2. The chlorinated rubber topcoat provided by this invention incorporates bisphenol A polyoxyethylene ether and zinc oxide as a stabilizer, enhancing the stability of the chlorinated rubber and preventing localized instability, particle agglomeration, and precipitation caused by uneven zinc oxide dispersion. The addition of bisphenol A polyoxyethylene ether also enhances the adhesion between the chlorinated rubber topcoat and the substrate by forming strong chemical bonds with the substrate surface. Furthermore, bisphenol A polyoxyethylene ether and chlorinated rubber have good compatibility, participating in the film-forming process and filling the gaps between chlorinated rubber molecules, resulting in a more uniform and dense paint film, thus improving the film's mechanical strength, weather resistance, and chemical corrosion resistance. Experiments have shown that zinc oxide and bisphenol A polyoxyethylene ether, used in a specific ratio in the chlorinated rubber topcoat provided by this invention, exhibit good flexibility, corrosion resistance, and weather resistance.

[0032] 3. The chlorinated rubber topcoat provided by this invention incorporates polyvinyl acetate and 52# chlorinated paraffin as a toughening agent, enhancing the flexibility of the paint film. Even at higher film thicknesses, it maintains excellent flexibility, improving the impact resistance and crack resistance of the paint film. The combination of polyvinyl acetate, with its strong adhesion and film-forming properties, and 52# chlorinated paraffin further enhances the adhesion between the coating and the substrate, improves anti-sagging properties, enhances the coating's application performance, effectively prevents settling and delamination, improves the uniformity, stability, and density of the paint film, and further enhances its aging resistance. Experiments have shown that a specific ratio of polyvinyl acetate to 52# chlorinated paraffin can maintain excellent flexibility in the paint film, improve its impact resistance, and enhance the adhesion between the coating and the substrate.

[0033] In summary, this invention uses alkyd resin, bisphenol A epoxy resin, and chlorinated rubber as film-forming resins, and further combines them with specific amounts of stabilizers, toughening agents, defoamers, wetting and dispersing agents, rheology control agents, pigments, fillers, and other additives to obtain a chlorinated rubber topcoat. The alkyd resin has an oil content of 60-70%, the bisphenol A epoxy resin has an epoxy equivalent of 180-210 g / mol, the stabilizer is a mixture of zinc oxide and bisphenol A polyoxyethylene ether at a mass ratio of 3-5:1, and the toughening agent is a mixture of 52# chlorinated paraffin and polyvinyl acetate at a mass ratio of 2-5:1. This improves the flexibility, impact resistance, adhesion, corrosion resistance, weather resistance, and gloss of the chlorinated rubber topcoat, making it suitable for long-term protection of ship above-waterline areas, bridges, chemical equipment, steel structures, etc. DETAILED DESCRIPTION

[0034] The effects are illustrated below with reference to specific examples.

[0035] Example 1:

[0036] S1: Add 20 parts xylene (solvent), 15 parts QT-6380 (alkyd resin), 2 parts E-51 (bisphenol A type epoxy resin), 2 parts DER 331 (bisphenol A type epoxy resin), 2 parts 52# chlorinated paraffin, 1 part PVAc 234K (polyvinyl acetate), 0.3 parts BYK-066N (defoamer), and 0.6 parts BYK-163 (wetting and dispersing agent) to a dispersion tank in sequence, adjust the rotation speed to 1200 r / min, and stir for 15 min;

[0037] S2: Add 1 part Bentone 828 (organic modified bentonite), 1 part SUPER (polyamide wax powder), 13 parts mica powder, 10 parts titanium dioxide, 12 parts iron oxide black, 0.4 parts zinc oxide, and 0.1 parts BPE-6 (bisphenol A polyoxyethylene ether) in sequence. After stirring evenly, transfer to a grinder for grinding until the fineness is <40µm to form a slurry.

[0038] S3: Add the slurry, 9 parts of CRF10 (chlorinated rubber, Ruize Chemical Co., Ltd.), and 9 parts of CR-20 (chlorinated rubber) to a dispersion tank, adjust the rotation speed to 900 r / min, stir for 18 min, adjust the viscosity to 105 KU, and filter to obtain the chlorinated rubber topcoat.

[0039] Example 2:

[0040] S1: Add 7 parts butyl acetate (solvent), 8 parts propylene glycol methyl ether acetate (solvent), 5 parts GL3303 (alkyd resin), 5 parts 389-9B (alkyd resin), 0.3 parts E-55 (bisphenol A type epoxy resin), 5 parts 52# chlorinated paraffin, 1 part PVAc195K (polyvinyl acetate), 0.1 parts NEO-5608 (defoamer), 0.2 parts EFKA4063 (wetting and dispersing agent), and 0.3 parts Anjeka-6161A (wetting and dispersing agent) to a dispersion tank in sequence, adjust the rotation speed to 800 r / min, and stir for 10 min;

[0041] S2: Add 1 part Bentone SD-2 (organic modified bentonite), 3 parts RC-800 (polyamide wax powder), 5 parts talc powder, 5 parts graphite powder, 25 parts titanium dioxide, 2.1 parts zinc oxide, and 0.7 parts BPE-10 (bisphenol A polyoxyethylene ether) in sequence. After stirring evenly, transfer to a grinder for grinding until the fineness is <40µm to form a slurry.

[0042] S3: Add the slurry and 15 parts of S-20 (chlorinated rubber) to a dispersion tank, adjust the rotation speed to 800 r / min, stir for 15 min, adjust the viscosity to 100 KU, and filter to obtain the chlorinated rubber topcoat.

[0043] Example 3:

[0044] S1: Add 25 parts S-800# (heavy aromatic solvent), 7 parts GL3303 (alkyd resin), 7 parts RV8111 (alkyd resin), 5 parts Epon Resin 828 (bisphenol A type epoxy resin), 3 parts 52# chlorinated paraffin, 0.5 parts PVAc 195K (polyvinyl acetate), 0.5 parts PVAc 189K (polyvinyl acetate), 0.2 parts BYK-065 (defoamer), 0.2 parts NEO-5608 (defoamer), and 0.8 parts BYK-163 (wetting and dispersing agent) to a dispersion tank in sequence, adjust the speed to 1500 r / min, and stir for 20 min;

[0045] S2: Add 1 part Bentone 27 (organic modified bentonite), 2 parts MT6650 (polyamide wax powder), 2 parts PA-8600 (polyamide wax powder), 15 parts mica powder, 10 parts phthalocyanine blue, 10 parts iron oxide black, 2.5 parts zinc oxide, 0.3 parts BPE-6 (bisphenol A polyoxyethylene ether), and 0.2 parts BPE-10 (bisphenol A polyoxyethylene ether) in sequence. After stirring evenly, transfer to a grinder for grinding until the fineness is <40µm to form a slurry.

[0046] S3: Add the slurry, 10 parts of CR-10 (chlorinated rubber), and 10 parts of CRF20 (chlorinated rubber, Ruize Chemical Co., Ltd.) to a dispersion tank, adjust the rotation speed to 1000 r / min, stir for 20 min, adjust the viscosity to 110 KU, and filter to obtain the chlorinated rubber topcoat.

[0047] Comparative Example 1:

[0048] The only difference between this comparative example and Example 1 is that in this comparative example, equal amounts (equal parts by weight, the same below) of chlorinated rubber CRF10 are used to replace alkyd resin QT-6380, bisphenol A type epoxy resin E-51, and DER 331.

[0049] Comparative Example 2:

[0050] The only difference between this comparative example and Example 1 is that an equal amount of alkyd resin QT-6906 with an oil content of 35-45% was used to replace alkyd resin QT-6380; and an equal amount of bisphenol A type epoxy resin DER 332 with an epoxy equivalent of 171-175 g / mol was used to replace bisphenol A type epoxy resin E-51 and DER 331.

[0051] Comparative Example 3:

[0052] The only difference between this comparative example and Example 1 is that this comparative example uses an equal amount of zinc oxide to replace bisphenol A polyoxyethylene ether BPE-6.

[0053] Comparative Example 4:

[0054] The only difference between this comparative example and Example 1 is that 0.1 parts of zinc oxide and 0.4 parts of BPE-6 were added to Comparative Example 4.

[0055] Comparative Example 5:

[0056] The only difference between this comparative example and Example 1 is that Comparative Example 5 contains 1 part of 52# chlorinated paraffin and 2 parts of PVAc234K.

[0057] Comparative Example 6:

[0058] The only difference between this comparative example and Example 1 is that Comparative Example 6 used 10 parts of 52# chlorinated paraffin and did not add polyvinyl acetate PVAc 234K.

[0059] The performance indicators of the chlorinated rubber topcoats of Examples 1-3 and Comparative Examples 1-6 were observed and measured (product standard: GB / T6745-2008 "Hood Coatings"). The results are shown in Table 1.

[0060] Table 1 Performance test results of chlorinated rubber topcoat

[0061]

[0062]

[0063] The test results in Table 1 show that Examples 1-3 provide a chlorinated rubber topcoat with good flexibility, impact resistance, corrosion resistance, weather resistance, high gloss, and good adhesion. It is suitable for surface protection of parts above the waterline of ships, bridges, chemical equipment, steel structures, etc., and extends the service life of the paint film.

[0064] Compared with Comparative Examples 1 and 2, Example 1 shows that the alkyd resin with an oil content of 60-70%, the bisphenol A type epoxy resin with an epoxy equivalent of 180-210 g / mol, and the chlorinated rubber significantly improve the gloss and flexibility of the paint film, and enhance its adhesion, mechanical strength, weather resistance and chemical corrosion resistance.

[0065] A comparison of Example 1 with Comparative Examples 3 and 4 reveals that the specific ratio of zinc oxide and bisphenol A polyoxyethylene ether used in the chlorinated rubber topcoat provided by this invention exhibits better flexibility, corrosion resistance, and weather resistance. The absence of bisphenol A polyoxyethylene ether, or alteration of the ratio of bisphenol A polyoxyethylene ether to zinc oxide, affects the flexibility, salt water resistance, salt spray resistance, artificial weathering resistance, and other properties of the coating film.

[0066] A comparison of Example 1 with Comparative Examples 5 and 6 revealed that the specific ratio of polyvinyl acetate to chlorinated paraffin 52# ​​maintained the excellent flexibility of the paint film, improved its impact resistance, and enhanced the adhesion between the coating and the substrate. The absence of polyvinyl acetate, or alteration of the ratio of polyvinyl acetate to chlorinated paraffin 52#, negatively impacted the excellent flexibility, impact resistance, and adhesion between the coating and the substrate.

Claims

1. A chlorinated rubber topcoat, characterized in that: The invention is compounded from the following components in parts by weight: 15-20 parts of chlorinated rubber, 10-15 parts of alkyd resin, 0.3-5 parts of bisphenol A epoxy resin, 3-6 parts of toughening agent, 15-25 parts of solvent, 0.1-0.4 parts of defoaming agent, 0.5-0.8 parts of wetting and dispersing agent, 2-5 parts of rheology control agent, 20-25 parts of pigment, 10-15 parts of filler and 0.5-3 parts of stabilizer. The alkyd resin is a long oil alkyd resin with an oil content of 60-70%; The epoxy equivalent of the bisphenol A epoxy resin is 180-210 g / mol; The stabilizer is a compound of zinc oxide and bisphenol A polyoxyethylene ether, and the mass ratio of the two is 3-5:1; The toughening agent is a compound of 52# chlorinated paraffin and polyvinyl acetate, and the mass ratio of the two is 2-5:1; The chlorine content of the chlorinated rubber is 64-68%; The rheology control additive is a compound of organic modified bentonite and polyamide wax powder, and the mass ratio of the two is 1:1-4; The solvent is at least one of xylene, butyl acetate, propylene glycol methyl ether acetate, and heavy aromatic hydrocarbons.

2. The chlorinated rubber topcoat according to claim 1, characterized in that: The wetting dispersant is a high molecular weight modified polyurethane dispersant.

3. The chlorinated rubber topcoat according to claim 1, characterized in that: The pigment is selected from at least one of titanium dioxide, phthalocyanine pigment or iron oxide pigment; The filler is selected from at least one of mica powder, talc powder and graphite powder.

4. The method for preparing the chlorinated rubber topcoat according to any one of claims 1 to 3, characterized in that: The steps include: S1: Add solvent, alkyd resin, bisphenol A epoxy resin, toughening agent, defoaming agent and wetting dispersant into a dispersion tank for stirring and dispersing; S2: Add rheology control agent, filler, pigment and stabilizer, stir evenly and transfer to grinder for grinding until the fineness is less than 40µm to form slurry; S3: Add the slurry and chlorinated rubber into a dispersion tank, stir and disperse, adjust the viscosity to 100-110KU, and filter to obtain the chlorinated rubber topcoat.

5. The method for preparing the chlorinated rubber topcoat as claimed in claim 4, characterized in that: The stirring and dispersing in step S1 is as follows: adjusting the rotation speed to 800-1500 r / min and stirring for 10-20 min.

6. The method for preparing the chlorinated rubber topcoat as claimed in claim 4, characterized in that: The stirring and dispersing in step S3 is as follows: adjusting the rotation speed to 800-1000 r / min and stirring for 15-20 min.

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