Preparation method of water-based finish paint for carbon fiber composite material

Abstract

The invention relates to a preparation method of a water-based finish paint for a carbon fiber composite material. The preparation method comprises the following steps: (1) mixing an acrylate monomer, a fluorine-containing acrylate monomer, a chain transfer agent and a part of an initiator to prepare a monomer premixed solution; adding a solvent into the reaction kettle, and adding a solution which accounts for 20-40% of the total amount of the monomer premixed solution; (2) mixing acrylic acid with the residual monomer premixed solution, and supplementing the mixture and the residual initiator into the reaction kettle; (3) adding deionized water, dispersing, and filtering to prepare a fluorine-modified water-based hydroxy acrylic dispersion with the solid content of 40-45wt%; (4) mixing and grinding the fluorine-modified water-based hydroxy acrylic acid dispersion, a filler, color paste, an auxiliary agent and deionized water to obtain a component A; diluting a water-based isocyanate curing agent with a solvent until the solid content is 40-80% to obtain a component B; the component A and the component B are mixed according to the mass ratio of (2-10): 1. The invention provides an environment-friendly water-based two-component finish paint with excellent adhesive force, mechanical property and weather resistance and a preparation method thereof.

Description

Technical Field

[0001] The invention relates to the technical field of organic fluorine modified coatings, and in particular to a method for preparing a water-based topcoat for carbon fiber composite materials. Background Art

[0002] Carbon fiber composites are widely used in the industrial field due to their light weight and high strength. However, the surface of this material is chemically inert, and traditional solvent-based topcoats have problems with insufficient interfacial adhesion and volatile organic compound emissions. Although existing water-based polyurethane topcoats have environmental advantages, there is still room for improvement in hardness, adhesion and weather resistance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of poor weather resistance and insufficient corrosion resistance of water-based carbon fiber composite material topcoats in the prior art, and to provide an environmentally friendly water-based two-component topcoat with excellent adhesion, mechanical properties and weather resistance and a preparation method thereof.

[0004] To solve the above technical problems, the technical solution of the present invention is a method for preparing a water-based topcoat for carbon fiber composite materials:

[0005] The following steps are involved:

[0006] (1) Mixing an acrylate monomer, a fluorinated acrylate monomer, a chain transfer agent, and a portion of an initiator to prepare a monomer premix; adding a solvent to a reaction kettle, heating the temperature to 80° C. to 110° C., adding a solution accounting for 20% to 40% of the total monomer premix, and keeping the temperature to react for 0.5 to 1 hour;

[0007] (2) Mixing acrylic acid with the remaining monomer premix, and adding the remaining initiator to the reactor at a uniform rate within 1-2 hours, and keeping the reaction at 80°C-110°C for 2-4 hours;

[0008] (3) cooling to room temperature, adding a neutralizer to adjust the pH to 7-9, adding deionized water for dispersion, and filtering to obtain a fluorine-modified aqueous hydroxy acrylic acid dispersion having a solid content of 40-45 wt%;

[0009] (4) Mixing and grinding the fluorine-modified water-based hydroxy acrylic dispersion with fillers, color pastes, additives, and deionized water to obtain component A; diluting the water-based isocyanate curing agent with a solvent to a solid content of 40%-80% to obtain component B; and mixing components A and B in a mass ratio of (2-10):1.

[0010] The components in step (1) include, by mass:

[0011] 80-100 parts of acrylic acid ester monomer;

[0012] 6-10 parts of fluorinated acrylate monomer;

[0013] 20-40 parts of solvent;

[0014] Chain transfer agent 0.05-0.2 parts

[0015] 1-2 parts initiator.

[0016] The acrylic acid ester monomer is selected from at least one of methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, lauryl acrylate, hexafluorobutyl methacrylate, and hydroxyethyl methacrylate.

[0017] The fluorine-containing acrylate monomer is selected from at least one of fluoroalkyl acrylate, fluoroalkyl methyl acrylate, hexafluorobutyl acrylate, and dodecafluoroheptyl methacrylate.

[0018] The remaining amount of initiator in step (2) accounts for 10-30% of the total mass of initiator.

[0019] The neutralizing agent in step (3) is selected from at least one of dimethylethanolamine, triethylamine, and ammonia water.

[0020] In the step (4),

[0021] The filler of component A comprises at least one of titanium dioxide and graphene oxide dispersion;

[0022] Additives include defoamers, wetting and leveling agents, dispersants and thickeners;

[0023] The solvent of component B is selected from at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether.

[0024] The initiator is selected from at least one of ammonium persulfate, azobisisobutyronitrile, and benzoyl peroxide; and the chain transfer agent is selected from at least one of allyl sulfide, mercaptoethanol, and dodecyl mercaptan.

[0025] The solvent in step (1) is selected from at least one of propylene glycol butyl ether, xylene, and trimethylbenzene.

[0026] The water-based isocyanate curing agent is a sulfonate-modified curing agent.

[0027] The technical effects that can be achieved by the present invention are:

[0028] 1. Fluorine-containing acrylate monomers are copolymerized with hydroxy acrylate to introduce fluorine-carbon bonds (CF) into the polymer chain. The bond energy is as high as 485kJ / mol, which significantly improves the weather resistance and chemical resistance of the coating.

[0029] 2. The abundant oxygen-containing functional groups (-OH, -COOH) on the surface of graphene oxide can form a hydrogen bond network with the resin. Its layered structure forms a maze effect in the coating, reducing the diffusion coefficient of the corrosive medium by 2 orders of magnitude.

[0030] 3. The gradient polymerization process forms core-shell structured polymer particles by controlling the monomer feeding sequence. The shell layer is enriched with fluorine to form a low surface energy protective layer, while the core layer retains hydroxyl groups to ensure the cross-linking density with the curing agent. DETAILED DESCRIPTION

[0031] The present invention will be further elaborated below.

[0032] A method for preparing a water-based topcoat for carbon fiber composite materials, comprising the following steps:

[0033] (1) Mixing an acrylate monomer, a fluorinated acrylate monomer, a chain transfer agent, and a portion of an initiator to prepare a monomer premix; adding a solvent to a reaction kettle, heating the temperature to 80° C. to 110° C., adding a solution accounting for 20% to 40% of the total monomer premix, and keeping the temperature to react for 0.5 to 1 hour;

[0034] (2) Mixing acrylic acid with the remaining monomer premix, and adding the remaining initiator to the reactor at a uniform rate within 1-2 hours, and keeping the reaction at 80°C-110°C for 2-4 hours;

[0035] (3) cooling to room temperature, adding a neutralizer to adjust the pH to 7-9, adding deionized water for dispersion, and filtering to obtain a fluorine-modified aqueous hydroxy acrylic acid dispersion having a solid content of 40-45 wt%;

[0036] (4) Mixing and grinding the fluorine-modified water-based hydroxy acrylic dispersion with fillers, color pastes, additives, and deionized water to obtain component A; diluting the water-based isocyanate curing agent with a solvent to a solid content of 40%-80% to obtain component B; and mixing components A and B in a mass ratio of (2-10):1.

[0037] Specifically, the components in step (1) include, by mass:

[0038] 80-100 parts of acrylic acid ester monomer;

[0039] 6-10 parts of fluorinated acrylate monomer;

[0040] 20-40 parts of solvent;

[0041] Chain transfer agent 0.05-0.2 parts

[0042] 1-2 parts initiator.

[0043] In step (1), the acrylate monomer is selected from at least one of methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, lauryl acrylate, hexafluorobutyl methacrylate, and hydroxyethyl methacrylate; the fluorine-containing acrylate monomer is selected from at least one of fluoroalkyl acrylate, fluoroalkyl methyl acrylate, hexafluorobutyl acrylate, and dodecafluoroheptyl methacrylate; and the solvent is selected from at least one of propylene glycol butyl ether, xylene, and trimethylbenzene;

[0044] The remaining amount of initiator in step (2) accounts for 10-30% of the total initiator mass.

[0045] The neutralizing agent in step (3) is selected from at least one of dimethylethanolamine, triethylamine and ammonia water.

[0046] In step (4),

[0047] The filler of component A comprises at least one of titanium dioxide and graphene oxide dispersion;

[0048] Additives include defoamers, wetting and leveling agents, dispersants and thickeners;

[0049] The solvent of component B is selected from at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether.

[0050] In steps (1) and (2), the initiator is selected from at least one of ammonium persulfate, azobisisobutyronitrile, and benzoyl peroxide; and the chain transfer agent is selected from at least one of allyl sulfide, mercaptoethanol, and dodecyl mercaptan.

[0051] In step (4), the water-based isocyanate curing agent is a sulfonate-modified curing agent.

[0052] The following are specific embodiments:

[0053] Example 1:

[0054] The preparation method of the fluorine-modified water-based hydroxy acrylic dispersion comprises the following steps:

[0055] Step 1: 80 parts of acrylic acid ester monomers: 30 parts by weight of methyl methacrylate, 30 parts by weight of hydroxyethyl methacrylate, and 20 parts by weight of n-butyl methacrylate;

[0056] 10 parts by weight of fluorinated acrylate monomer: 10 parts by weight of dodecafluoroheptyl methacrylate;

[0057] 1 part by weight of initiator: 1 part by weight of benzoyl peroxide;

[0058] 0.2 parts by weight of chain transfer agent: 0.1 parts by weight of dodecyl mercaptan, 0.1 parts by weight of mercaptoethanol;

[0059] Premixing in a batching tank to prepare a monomer premix solution; adding 40 parts by weight of a solvent (propylene glycol butyl ether) to a reactor equipped with a stirring device and a reflux condenser, heating to 80° C. and maintaining a constant temperature, uniformly adding 27 parts by weight of the monomer premix solution prepared in step 1 dropwise, controlling the dropping speed so that the mixed solution is added within 1 hour, maintaining a stirring speed of 500 r / min and conducting a free radical polymerization reaction for 0.5 hour;

[0060] Step 2: Slowly add a mixture of 12 parts by weight of acrylic acid, the remaining monomer premix, and 0.12 parts by weight of initiator (benzoyl peroxide) to the reaction system through a constant pressure dropping funnel. The addition time is controlled to 1 hour, and the reaction is continued at 110° C. for 4 hours.

[0061] Step 3: After the reaction system is naturally cooled to 25°C, 25% by mass of ammonia water is added to adjust the pH value of the system to 9 (ammonia water), and deionized water is added to adjust the solid content to 45wt%. The mixture is filtered through a 200-mesh stainless steel filter to obtain a fluorine-modified water-based hydroxy acrylic acid dispersion.

[0062] Step 4: The preparation method of high-performance water-based carbon fiber composite material topcoat includes:

[0063] 1. 60 parts by weight of the fluorine-modified aqueous hydroxy acrylic dispersion;

[0064] 15 parts by weight of deionized water;

[0065] 11.5 parts by weight of additives: 2 parts by weight of BYK-190 dispersant, 0.5 parts by weight of BYK-024 defoamer, 6 parts by weight of dipropylene glycol methyl ether acetate film-forming aid, 0.5 parts by weight of TEGO Flow 425 wetting and leveling agent, 0.5 parts by weight of BYK-381 leveling agent, and 2 parts by weight of polyurethane associative thickener (RM-8W);

[0066] 1 part by weight of color paste: 1 part by weight of water-based carbon black paste;

[0067] 25 parts by weight of filler: 25 parts by weight of rutile titanium dioxide (R-996);

[0068] Add the ingredients in sequence into a high-speed disperser and disperse them at a speed of 500 r / min for 45 minutes until the fineness is ≤15 μm to prepare component A;

[0069] 2. Dilute the sulfonate-modified waterborne HDI trimer curing agent (Bayhydur XP 2655) and propylene glycol methyl ether acetate to a solid content of 40 wt% to prepare component B;

[0070] 3: Mix component A and component B in a mass ratio of 10:1, let it stand and mature for 30 minutes to obtain a water-based carbon fiber composite material topcoat.

[0071] Example 2:

[0072] The preparation method of the fluorine-modified water-based hydroxy acrylic dispersion comprises the following steps:

[0073] Step 1: 100 parts of acrylic acid ester monomers: 20 parts by weight of isooctyl acrylate, 30 parts by weight of lauryl acrylate, 20 parts by weight of hexafluorobutyl methacrylate, and 30 parts by weight of hydroxyethyl methacrylate;

[0074] 6 parts by weight of fluorinated acrylate monomers: 2 parts by weight of fluoroalkyl acrylate, 2 parts by weight of fluoroalkyl methyl acrylate, and 2 parts by weight of hexafluorobutyl acrylate;

[0075] 2 parts by weight of initiator: 1 part by weight of ammonium persulfate, 1 part by weight of azobisisobutyronitrile;

[0076] 0.05 parts by weight of chain transfer agent: 0.05 parts by weight of allyl sulfide;

[0077] Premixing in a batching tank to prepare a monomer premix solution; adding 20 parts by weight of a solvent (10 parts by weight of xylene and 10 parts of trimethylbenzene) to a reactor equipped with a stirring device and a reflux condenser, heating to 110° C. and maintaining a constant temperature, uniformly adding 22 parts by weight of the monomer premix solution prepared in step 1 dropwise, controlling the dropping speed so that the mixed solution is added within 1 hour, maintaining a stirring speed of 500 r / min and conducting a free radical polymerization reaction for 1 hour;

[0078] Step 2: Slowly add a mixture consisting of 12 parts by weight of acrylic acid, the remaining monomer premix, and 0.86 parts by weight of initiator (ammonium persulfate) to the reaction system through a constant pressure dropping funnel. The addition time is controlled to be 2 hours, and the reaction is continued at 80°C for 2 hours.

[0079] Step 3: After the reaction system is naturally cooled to 25°C, 25% by mass of ammonia water is added to adjust the pH value of the system to 7 (triethylamine, dimethylethanolamine), and deionized water is added to adjust the solid content to 40wt%. The mixture is filtered through a 200-mesh stainless steel filter to obtain a fluorine-modified aqueous hydroxy acrylic acid dispersion.

[0080] Step 4: The preparation method of high-performance water-based carbon fiber composite material topcoat includes:

[0081] 1. 60 parts by weight of the fluorine-modified aqueous hydroxy acrylic dispersion;

[0082] 15 parts by weight of deionized water;

[0083] 11.5 parts by weight of additives: 2 parts by weight of BYK-190 dispersant, 0.5 parts by weight of BYK-024 defoamer, 6 parts by weight of dipropylene glycol methyl ether acetate film-forming aid, 0.5 parts by weight of TEGO Flow 425 wetting and leveling agent, 0.5 parts by weight of BYK-381 leveling agent, and 2 parts by weight of polyurethane associative thickener (RM-8W);

[0084] 1 part by weight of color paste: 1 part by weight of water-based carbon black paste;

[0085] 25 parts by weight of filler: 15 parts by weight of rutile titanium dioxide (R-996), 10 parts of graphene oxide dispersion;

[0086] Add in sequence in a high-speed disperser and disperse at a speed of 500 r / min for 45 minutes until the fineness is ≤15 μm to prepare component A;

[0087] 2. Dilute the sulfonate-modified waterborne HDI trimer curing agent (Bayhydur XP 2655) and dipropylene glycol dimethyl ether to a solid content of 80 wt% to prepare component B;

[0088] 3. Mix component A and component B in a mass ratio of 2:1, let it stand and mature for 30 minutes to obtain a water-based carbon fiber composite material topcoat.

[0089] Example 3:

[0090] The preparation method of the fluorine-modified water-based hydroxy acrylic dispersion comprises the following steps:

[0091] Step 1: 90 parts of acrylic acid ester monomers: 10 parts by weight of methyl methacrylate, 20 parts by weight of n-butyl methacrylate, 20 parts by weight of lauryl acrylate, 20 parts by weight of hexafluorobutyl methacrylate, and 20 parts by weight of hydroxyethyl methacrylate;

[0092] 8 parts by weight of fluorinated acrylate monomers: 2 parts by weight of dodecafluoroheptyl methacrylate, 2 parts by weight of fluoroalkyl acrylate, 2 parts by weight of fluoroalkyl methyl acrylate, and 2 parts by weight of hexafluorobutyl acrylate;

[0093] 1.5 parts by weight of initiator: 1 part by weight of ammonium persulfate, 0.5 part by weight of benzoyl peroxide;

[0094] 0.1 parts by weight of chain transfer agent: 0.05 parts by weight of allyl sulfide, 0.05 parts by weight of mercaptoethanol;

[0095] Premixing in a batching tank to prepare a monomer premix solution; adding 30 parts by weight of a solvent (xylene) to a reactor equipped with a stirring device and a reflux condenser, heating to 90° C. and maintaining a constant temperature, uniformly adding 39 parts by weight of the monomer premix solution prepared in step 1 dropwise, controlling the dropping speed so that the mixed solution is added within 1 hour, maintaining a stirring speed of 500 r / min and conducting a free radical polymerization reaction for 0.8 hour;

[0096] Step 2: Slowly add a mixture of 12 parts by weight of acrylic acid, the remaining monomer premix, and 0.4 parts by weight of initiator (azobisisobutyronitrile) to the reaction system through a constant pressure dropping funnel. The addition time is controlled to be 1.5 hours, and the reaction is continued at 100°C for 3 hours.

[0097] Step 3: After the reaction system is naturally cooled to 25°C, 25% by mass of ammonia water is added to adjust the pH value of the system to 8 (triethylamine), and deionized water is added to adjust the solid content to 43wt%. The mixture is filtered through a 200-mesh stainless steel filter to obtain a fluorine-modified aqueous hydroxy acrylic acid dispersion.

[0098] Step 4: The preparation method of high-performance water-based carbon fiber composite material topcoat includes:

[0099] 1. 60 parts by weight of the fluorine-modified aqueous hydroxy acrylic dispersion;

[0100] 15 parts by weight of deionized water;

[0101] 11.5 parts by weight of additives: 2 parts by weight of BYK-190 dispersant, 0.5 parts by weight of BYK-024 defoamer, 6 parts by weight of dipropylene glycol methyl ether acetate film-forming aid, 0.5 parts by weight of TEGO Flow 425 wetting and leveling agent, 0.5 parts by weight of BYK-381 leveling agent, and 2 parts by weight of polyurethane associative thickener (RM-8W);

[0102] 1 part by weight of color paste: 1 part by weight of water-based carbon black paste;

[0103] 25 parts by weight of filler: 25 parts by weight of graphene oxide dispersion;

[0104] Add in sequence in a high-speed disperser and disperse at a speed of 500 r / min for 45 minutes until the fineness is ≤15 μm to prepare component A;

[0105] 2. Dilute the sulfonate-modified waterborne HDI trimer curing agent (Bayhydur XP 2655) with butyl acetate at a solid content of 60 wt% to prepare component B;

[0106] 3: Mix component A and component B in a mass ratio of 4:1, let it stand and mature for 30 minutes to obtain a water-based carbon fiber composite material topcoat.

[0107] Performance testing:

[0108] The coating performance test of the topcoat prepared in the above embodiment is carried out, and the test results are shown in Table 1. The test method is based on the requirements of the HG / T4761-2014 "Waterborne Polyurethane Coatings" standard. The specific test results are as follows:

[0109] Table 1 Coating performance test

[0110]

[0111]

[0112] By comparing the above embodiments with the existing situation, the advantages of the present invention are: providing a water-based environmentally friendly topcoat with high hardness and high gloss for carbon fiber composite materials. The water-based polyurethane topcoat developed by the original industry standard is not suitable for carbon fiber composite materials, and is generally suitable for metal substrates or inorganic non-metallic substrates.

[0113] The beneficial effects of the present invention are embodied in:

[0114] (1) Achieve orderly distribution of fluorine in the polymer chain through the gradient feeding process of fluorine-containing monomers;

[0115] (2) The intercalation dispersion of graphene oxide significantly improves the corrosion resistance of the coating;

[0116] (3) After the two-component system is cured into a film, the pencil hardness of the coating reaches above 2H and the adhesion grade is 0;

[0117] (4) Water resistance test (96h immersion) shows no blistering or shedding.

[0118] (5) Adhesion (cross-hatch method): Grade 0, pencil hardness ≥ 3H;

[0119] (6) VOC content is less than 80g / L, in compliance with GB / T 38597-2020 environmental protection standard (general water-based industrial protective coatings less than 250g / L).

Claims

1. A method for preparing a water-based topcoat for carbon fiber composite materials, characterized in that: The following steps are involved: (1) Mixing an acrylate monomer, a fluorinated acrylate monomer, a chain transfer agent, and a portion of an initiator to prepare a monomer premix; adding a solvent to a reaction kettle, heating the temperature to 80° C. to 110° C., adding a solution accounting for 20% to 40% of the total monomer premix, and keeping the temperature to react for 0.5 to 1 hour; (2) Mixing acrylic acid with the remaining monomer premix, and adding the remaining initiator to the reactor at a uniform rate within 1-2 hours, and keeping the reaction at 80°C-110°C for 2-4 hours; (3) cooling to room temperature, adding a neutralizer to adjust the pH to 7-9, adding deionized water for dispersion, and filtering to obtain a fluorine-modified aqueous hydroxy acrylic acid dispersion having a solid content of 40-45 wt%; (4) Mixing and grinding the fluorine-modified water-based hydroxy acrylic dispersion with fillers, color pastes, additives, and deionized water to obtain component A; diluting the water-based isocyanate curing agent with a solvent to a solid content of 40%-80% to obtain component B; and mixing components A and B in a mass ratio of (2-10):

1.

2. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: The components in step (1) include, by mass: 80-100 parts of acrylic acid ester monomer; 6-10 parts of fluorinated acrylate monomer; 20-40 parts of solvent; Chain transfer agent 0.05-0.2 parts 1-2 parts initiator.

3. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 2, characterized in that: The acrylic acid ester monomer is selected from at least one of methyl methacrylate, n-butyl methacrylate, isooctyl acrylate, lauryl acrylate, hexafluorobutyl methacrylate, and hydroxyethyl methacrylate.

4. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 2, characterized in that: The fluorine-containing acrylate monomer is selected from at least one of fluoroalkyl acrylate, fluoroalkyl methyl acrylate, hexafluorobutyl acrylate, and dodecafluoroheptyl methacrylate.

5. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: The remaining amount of initiator in step (2) accounts for 10-30% of the total mass of the initiator.

6. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: The neutralizing agent in step (3) is selected from at least one of dimethylethanolamine, triethylamine, and ammonia water.

7. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: In the step (4), The filler of component A comprises at least one of titanium dioxide and graphene oxide dispersion; Additives include defoamers, wetting and leveling agents, dispersants and thickeners; The solvent of component B is selected from at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether.

8. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: The initiator is selected from at least one of ammonium persulfate, azobisisobutyronitrile, and benzoyl peroxide; and the chain transfer agent is selected from at least one of allyl sulfide, mercaptoethanol, and dodecyl mercaptan.

9. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: The solvent in step (1) is selected from at least one of propylene glycol butyl ether, xylene, and trimethylbenzene.

10. The method for preparing a water-based topcoat for carbon fiber composite materials according to claim 1, characterized in that: The water-based isocyanate curing agent is a sulfonate-modified curing agent.

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