CN115594995A - Preparation method of filler for coating - Google Patents
Preparation method of filler for coating Download PDFInfo
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- CN115594995A CN115594995A CN202210963815.4A CN202210963815A CN115594995A CN 115594995 A CN115594995 A CN 115594995A CN 202210963815 A CN202210963815 A CN 202210963815A CN 115594995 A CN115594995 A CN 115594995A
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/006—Combinations of treatments provided for in groups C09C3/04 - C09C3/12
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/06—Treatment with inorganic compounds
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
- C09C3/08—Treatment with low-molecular-weight non-polymer organic compounds
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
- C09D175/04—Polyurethanes
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- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/24—Electrically-conducting paints
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2004/01—Particle morphology depicted by an image
- C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
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- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/001—Conductive additives
Abstract
The invention provides a preparation method of a filling material for a coating, which comprises the steps of carrying out mixed acid surface pretreatment, electrochemical purification of functional groups and electro-grafting treatment on graphene in sequence, so that the finally obtained functionalized graphene has extremely high water solubility, and the abundant double bonds on the surface of the functionalized graphene are bonded with other polymers by chemical bonds, thereby increasing the crosslinking density, improving the physical and chemical properties of the polyurethane coating, and particularly remarkably improving the corrosion resistance of the coating.
Description
Technical Field
The invention relates to the technical field of water-based paint, relates to a preparation method of a water-based two-component paint composition, and particularly relates to a surface treatment method of an inorganic filler in paint.
Background
Polyurethane (PU) is a polyurethane, which is called "microphase separation", and is prepared by the addition polycondensation of isocyanate and an active hydrogen-containing compound, wherein the molecular chain contains repeated carbamate groups (-NH-COO-), and is a high molecular compound with a block structure, which is formed by inlaying a rigid chain segment (hard segment) with a high glass transition temperature and a flexible chain segment (soft segment) with a low glass transition temperature, an oligomer polyol such as polyether and polyester forms a soft segment, the molecular weight is generally 300-3000 g/mol, a diisocyanate and a chain extender (low molecular weight polyols, polyamines) with a small molecular weight form a hard segment, the polarities of the soft segment and the soft segment are different and incompatible with each other, the polarities of the hard segment and the hard segment are strong, the attraction force between the hard segment and the diisocyanate is large, and the diisocyanate and the chain extender are easily aggregated together to form a plurality of domains distributed in the soft segment. Meanwhile, the hard segment provides multi-functionality crosslinking, the soft segment matrix is crosslinked by the hard segment phase region, and different oligomer polyols react with isocyanate to obtain polyurethane with different properties.
Polyurethane is used as a high polymer material, and has the advantages of wide hardness adjustment range, low temperature resistance, good flexibility, strong adhesive force, wear resistance, chemical resistance and the like since the polyurethane is synthesized for the first time, so that the polyurethane can be widely applied to the industries of foamed plastics, rubber, adhesives, synthetic leather fibers, coatings and the like, wherein the polyurethane coating is a common coating at present, and a polyurethane product occupies a special position in the use of the coating.
Graphene has been proven to have many desirable properties, such as high mechanical strength, electrical conductivity, molecular barrier capability, and other remarkable characteristics, and at present, it is a research focus to improve the inherent properties or impart new functions by modifying an aqueous coating with graphene, and the key is to improve the dispersion compatibility of graphene in a polymer. In general, the surface energy of graphene is reduced by in-situ polymerization, electrodeposition and the like, and then effective dispersion in a coating is realized by physical blending, repulsion between functional groups or bonding with a resin coating.
For example, tianjin university of industry CN201910987015 discloses a preparation method of a functionalized graphene reinforced aqueous polyurethane anticorrosive coating. The preparation method mainly comprises the steps of preparing Graphite Oxide (GO) and performing functional modification on the graphite oxide, doping the functionalized graphene oxide into a water-based polyurethane coating, and finally coating the composite coating on the surface of metal by using a bar coating or spraying method. The method is characterized in that: (1) The graphene anticorrosive coating with high anticorrosive efficiency is prepared by taking functionalized graphene oxide as an enhancer and aqueous polyurethane as a matrix: (2) The modified graphene oxide has good dispersibility and compatibility in waterborne polyurethane; (3) The anticorrosive effect of the modified anticorrosive coating is greatly improved compared with that of pure water polyurethane; (4) The functionalized graphene can be used as doped particles of a water-based paint and coated on a protected metal surface in a brush coating or spraying manner.
For example, CN202111345795 discloses a polyacrylate functionalized graphene modified polyurethane composite coating, which has excellent flame retardancy and mechanical properties compared with pure polyurethane coating, when the composite coating is burned, graphene oxide forms a protective carbon layer to increase the flame retardancy of the coating, and graphene is uniformly dispersed in the coating to increase the mechanical properties of the coating, and a phosphorus-containing flame retardant forms polymetaphosphoric acid when heated, which not only prevents burning, but also forms an expanded carbon layer to increase the flame retardancy of the coating.
For example, CN202210422718 discloses a flame-retardant hydrophobic biomass-based waterborne polyurethane coating and a preparation method thereof, wherein the preparation method comprises the following steps: preparing an isocyanate-terminated polyurethane prepolymer; (2) preparing biomass functionalized graphene; (3) preparing a water-based polyurethane emulsion; (4) And (4) adding a thickening agent, a flatting agent and a defoaming agent into the aqueous polyurethane emulsion prepared in the step (3), and stirring at a high speed to obtain the flame-retardant hydrophobic biomass-based aqueous polyurethane coating. The invention also provides the flame-retardant hydrophobic biomass-based waterborne polyurethane coating prepared by the method, and the flame-retardant hydrophobic biomass-based waterborne polyurethane coating prepared by the method has better hydrophobicity, flame retardance and mechanical property; after the finishing agent is applied to fabric finishing, the water contact angle of the fabric can reach more than 140 degrees, and the flame retardant grade can reach B2 grade and above.
Disclosure of Invention
Based on the problem of dispersion of graphene in the coating in the prior art, the invention provides a preparation method of graphene filler for the coating, which comprises the steps of carrying out surface pretreatment on the conductive filler, wherein the pretreatment is mixed acid treatment, a large number of defect sites with functional groups, such as-OH, -CHO, -COOH, are arranged on the surface of the graphene conductive filler through the mixed acid treatment, then carrying out electrochemical oxidation or reduction treatment under the stirring condition, mainly oxidation treatment of an anode chamber, purifying the functional groups into-COOH, further improving the grafting effect of the graphene in subsequent electrochemical grafting of double-bond sulfonyl, and finally obtaining functionalized graphene with extremely high water solubility, wherein the abundant double bonds on the surface of the functionalized graphene are bonded with other polymers through chemical bonds, so that the crosslinking density is increased, and the physical and chemical properties of the composite coating are improved.
The specific treatment steps of the filler are as follows:
(1) And carrying out surface pretreatment on the conductive filler.
(2) And carrying out electrochemical purification treatment on the filler.
(3) And (4) ultrasonic stripping.
(4) Repeating the step (2) and the step (3) for multiple times.
(5) Electrochemically grafting the double-bond-rich sulfonyl group.
(6) And (5) post-treatment.
The conductive material is graphene, and the surface treatment process comprises the following steps:
taking 300-400mg of commercially available graphene powder, placing the commercially available graphene powder in a three-neck flask containing a mixed solution of sulfuric acid and nitric acid, carrying out reflux treatment at 100 ℃ for 3-4h, naturally cooling, filtering, and washing until the pH =5-6 to obtain a graphene suspension.
The electrochemical purification process is as follows: placing the graphene suspension obtained in the step (1) in an anode chamber of an electrolytic cell containing a diaphragm, stirring, and carrying out constant-current or constant-current electrochemical purification treatment by using a platinum sheet as an anode and a carbon rod as a cathode, wherein the constant voltage is as follows: 1.5-3V constant voltage treatment for 15-17 minutes; or applying 0.5-2mA constant current for 17-19 min at 30-35 deg.C and stirring speed of 800-900rpm.
Ultrasonic stripping, namely turning off the power supply of the electrolytic cell, turning on the ultrasonic crusher, and placing an ultrasonic vibrating rod of the ultrasonic crusher in the anode chamber, wherein the ultrasonic frequency is 5000-6000Hz, and the ultrasonic time is 1-2min.
And (5) repeating the step (4) for 5-8 times to obtain the purified graphene suspension.
Electrochemical grafting double bond-rich sulfonyl:
dissolving 1-2mmol of 4-methylbenzenesulfonyl hydrazide in a methanol solvent, adding 10-13wt% of tetrabutylammonium iodide, 5-10ml of saturated ammonium carbonate and 7-10g of purified graphene suspension, and adjusting the pH to 8-9 by using potassium hydroxide under the electrochemical conditions of 40-50mA for 4-5h at the temperature of 25-30 ℃.
The post-treatment process is as follows: filtering after full reaction, repeatedly washing with ethanol and acetone alternately, and ultrasonically dispersing the filtrate in deionized water containing surfactant to obtain the filler suspension for coating.
Further, the mass ratio of the nitric acid to the sulfuric acid is 3: 1.
Further, the filter membrane used in the filtration in the step (1) is selected from a 0.45 μm meta-fluorine membrane.
Further, the mass fraction of the purified graphene in the purified graphene suspension is 10-15%.
Further, the filler suspension for the coating contains 15-20wt.% of double-bond-rich sulfonyl modified graphene, 1-2 wt.% of surfactant and deionized water.
Further, the coating is a water-based two-component polyurethane coating.
Further, the coating is prepared by the following steps: firstly, sequentially adding a hydroxyl acrylic resin dispersoid, a defoaming agent, a leveling agent, a dispersing agent, a film-forming assistant, a bactericide and a thickening agent into a stirring container containing water, stirring at 300-400rpm for 15-20min, then adding a pigment and matting powder, increasing the stirring at 2000-2300 rpm, dispersing for 50-60min, then adding a modified graphene suspension, stirring at 500-600rpm for 5-10min, standing in the shade for eliminating bubbles to obtain a component A, then adding a curing agent component B, stirring at 200-300rpm, adding a proper amount of water for diluting to construction viscosity, and filtering with 200-mesh filter cloth to obtain the double-component waterborne polyurethane coating.
The modified graphene suspension contains 15-20wt.% of double-bond-rich sulfonyl modified graphene, 1-2wt% of surfactant and deionized water.
Further, the defoaming agent is BKY-024, the leveling agent is BKY-348, the dispersing agent is digao 760w, the film-forming aid is Texanol film-forming aid, the bactericide is imidazole bactericide, and the thickener is selected from R-420 thickeners.
The pigment is titanium dioxide, and the matting powder is OK-500 matting powder.
The curing agent is an isocyanate curing agent.
Further, the coating comprises the following components in parts by mass:
the component A comprises:
50-60 parts of hydroxyl acrylic resin dispersion;
0.2-0.3 part of BKY-024 defoaming agent;
0.3-0.4 part of BKY-348 leveling agent;
0.2-0.3 part of Digao 760w dispersant;
1.5-2.0 parts of Texanol film-forming additive;
0.1-0.15 part of imidazole bactericide;
0.5-0.6 part of R-420 thickening agent;
15-20 parts of titanium dioxide pigment;
2-3 parts of OK-500 matting powder;
15-20 parts of modified graphene suspension;
and the component B comprises:
18-20 parts of isocyanate curing agent.
The modified graphene suspension contains 15-20wt.% double-bond-rich sulfonyl modified graphene, 1-2 wt.% of surfactant and deionized water, and the surfactant is P123 nonionic surfactant.
As known by persons skilled in the art, graphene sheets of graphene have strong van der Waals force, so that the graphene sheets are not suitable for dispersing in an organic coating, in addition, inorganic nano graphene has poor compatibility with a high molecular polymer, and interface bonding force is weak, so that how to improve the dispersion phase of graphene in an aqueous solution directly influences the physicochemical property of the graphene coating, in order to improve the hydrophilicity of graphene, 300-400mg of commercially available graphene powder is placed in a three-neck flask containing a sulfuric acid and nitric acid mixed solution, reflux treatment is carried out for 3-4h at 100 ℃, after natural cooling, filtration is carried out, and washing is carried out until the pH =5-6, so that a graphene suspension is obtained. In the process, firstly, hydrophilic groups are considered to be introduced on the surface of graphene, and functional hydrophilic groups are considered to be introduced by using mixed acid heat treatment, for example, after the graphene is subjected to acid treatment functionalization, a large number of defect sites with functional groups, such as-OH, -CHO, -COOH, are introduced on the surface of the graphene, and the distribution of the surface energy of the graphene is changed due to the change of the microenvironment of the surface, so that the dispersity of the graphene in water is improved.
In order to effectively homogenize or purify functional groups on the surface of graphene, the functional groups on the surface of graphene can be effectively purified through electrochemical treatment, such as acidification treatment and enhanced hydrophilicity of the surface of graphene, wherein the hydrophilicity is mainly-OH, -CHO, -COOH or other dioxygen or heterocyclic epoxy, the graphene suspension obtained in the step (1) is placed in an anode chamber of an electrolytic cell containing a diaphragm and is stirred, and constant-current or constant-current electrochemical purification treatment is carried out by taking a platinum sheet as an anode and a carbon rod as a cathode, wherein the constant-voltage is: 1.5-3V constant voltage treatment for 15-17 minutes; or applying 0.5-2mA constant current for 17-19 minutes, the temperature is 30-35 ℃, the stirring speed is 800-900rpm, the reaction formula mainly involved in the process is the oxidation process of the reducing group, taking the original hydroxyl as an example, the possible reaction processes in the anode chamber are as follows:
GE-CH 2 -OH+2H 2 O-4e - →GE-COOH+4H + 。
various functional groups on the surface of the graphene are subjected to anodic oxidation treatment and carboxylation, so that the functional groups on the surface of the graphene are effectively and uniformly purified, and a solid basis is provided for subsequent electrochemical grafting.
The very necessary treatment condition in the electrochemical process is stirring, only through stirring, a foundation can be provided for the contact between the graphene and the anode electrode, only the contact between the graphene and the anode can be conducted, and the groups on the surface of the graphene can be purified, in contrast, the graphene in the electrolyte cannot be purified.
As above-mentioned, only graphite alkene and electrode take place the electrical contact and just can realize the purification process, and simultaneously at the stirring in-process, graphite alkene probably itself can take place to pile up or reunite, perhaps graphite alkene laminating is on the electrode surface and unable timely break away from, and this all can influence the purification process of graphite alkene, consequently, can not long-time electrochemistry purification treatment graphite alkene, need intermittently introduce ultrasonic treatment in the purification process: closing the power supply of the electrolytic cell, opening the ultrasonic crusher, placing an ultrasonic vibrating rod of the ultrasonic crusher in the anode chamber, performing ultrasonic treatment at an ultrasonic frequency of 5000-6000Hz for 1-2min, and circularly performing purification and ultrasonic treatment, wherein the ultrasonic effects are two: the method has the advantages that graphene on the surface of the electrode is separated, self-agglomerated graphene is vibrated and stripped, and then high-dispersion graphene suspension electrolyte is formed.
Then introducing double-bond-rich sulfonyl on the surface of GE-COOH, wherein the possible electrochemical reaction mechanism is shown in figure 1, the double bonds can improve the dispersion compatibility and the interface bonding force of graphene and a coating and a polymer, and the benzene ring structure improves the rigidity of the coating.
The graphene filler can be applied to various conventional coatings without any limitation in usability, such as conventional coatings of polyurethane, epoxy resin, methyl acrylate, fluorinated resin, electrocoating, and the like. In order to examine the influence of graphene on the physical and chemical properties of the coating, a two-component polyurethane coating is used for description.
The preparation method of the coating comprises the following steps: firstly, sequentially adding a hydroxyl acrylic resin dispersoid, a defoaming agent, a leveling agent, a dispersing agent, a film-forming assistant, a bactericide and a thickening agent into a stirring container containing water, stirring at 300-400rpm for 15-20min, then adding a pigment and matting powder, increasing the stirring at 2000-2300 rpm, dispersing for 50-60min, then adding a modified graphene suspension, stirring at 500-600rpm for 5-10min, standing in the shade for eliminating bubbles to obtain a component A, then adding a curing agent component B, stirring at 200-300rpm, adding a proper amount of water for diluting to construction viscosity, and filtering with 200-mesh filter cloth to obtain the double-component waterborne polyurethane coating.
The modified graphene suspension contains 15-20wt.% of double-bond-rich sulfonyl modified graphene, 1-2wt% of surfactant and deionized water.
The defoamer is BKY-024, the flatting agent is BKY-348, the dispersant is digao 760w, the film-forming aid is Texanol film-forming aid, the bactericide is imidazole bactericide, and the thickener is R-420 thickener.
The pigment is titanium dioxide, and the matting powder is OK-500 matting powder.
The curing agent is an isocyanate curing agent.
Specifically, the two-component coating comprises the following components in parts by mass:
the component A comprises:
50-60 parts of a hydroxy acrylic resin dispersion;
0.2-0.3 part of BKY-024 defoaming agent;
0.3-0.4 part of BKY-348 leveling agent;
0.2-0.3 part of digao 760w dispersant;
1.5-2.0 parts of Texanol film-forming additive;
0.1-0.15 part of imidazole bactericide;
0.5-0.6 part of R-420 thickening agent;
15-20 parts of titanium dioxide pigment;
2-3 parts of OK-500 matting powder;
15-20 parts of modified graphene suspension;
and B component:
18-20 parts of isocyanate curing agent.
The modified graphene suspension contains 15-20wt.% double-bond-rich sulfonyl modified graphene, 1-2wt% of surfactant and deionized water, and the surfactant is P123 nonionic surfactant.
Advantageous technical effects
According to the invention, the graphene conductive filler is subjected to surface pretreatment, namely mixed acid treatment, a large number of defect sites with functional groups, such as-OH, -CHO, -COOH, are arranged on the surface of the graphene conductive filler through the mixed acid treatment, then electrochemical oxidation or reduction treatment is carried out under the stirring condition, mainly oxidation treatment of an anode chamber is carried out, the functional groups are purified to be-COOH, the grafting effect of the graphene on subsequent electrochemical grafting of double-bond-rich sulfonyl is further improved, the finally obtained functionalized graphene has extremely high water solubility, and the rich double bonds on the surface are bonded with other polymers through chemical bonds, so that the crosslinking density is increased, and the physical and chemical properties of the composite coating are improved.
Drawings
FIG. 1 is a diagram of the electrochemical treatment mechanism of the present invention.
FIG. 2 is a surface SEM topography of the polyurethane coating.
FIG. 3 is a neutral salt spray test chart of the coating of the present invention.
FIG. 4 is an SEM image of purified graphene according to the present invention.
FIG. 5 is a TEM topography of the purified graphene of the present invention.
FIG. 6 optical diagram of a filler suspension for a coating according to the invention.
FIG. 7 is a graph of the polarization of the inventive and comparative coatings.
Detailed Description
In order to embody the specific effect of the modified graphene in the coating, the polyurethane is used as a coating material for testing, and the preparation method of the coating comprises the following steps: firstly, sequentially adding a hydroxyl acrylic resin dispersoid, a defoaming agent, a leveling agent, a dispersing agent, a film-forming assistant, a bactericide and a thickener into a stirring container containing water, stirring at 350rpm for 17.5min, then adding a pigment and a matting powder, increasing the stirring speed to 2150 rpm, dispersing for 55min, then adding a modified graphene suspension, stirring at 550rpm, dispersing for 7.5min, standing in the shade to eliminate bubbles to obtain a component A, then adding a curing agent component B, stirring at 250rpm, adding a proper amount of water to dilute to construction viscosity, filtering with 200-mesh filter cloth to obtain the two-component waterborne polyurethane coating, and then spraying the coating on the surface of a metal, wherein the coating can be stainless steel, aluminum alloy or other various metal materials, and the embodiment takes stainless steel as an example.
The coating composition obtained was as follows:
the component A comprises:
55 parts of a hydroxy acrylic resin dispersion;
0.25 part of BKY-024 defoaming agent;
0.35 part of BKY-348 leveling agent;
0.25 part of digao 760w dispersant;
1.75 parts of Texanol film-forming additive;
0.125 part of imidazole bactericide;
0.55 part of R-420 thickening agent;
17.5 parts of titanium dioxide pigment;
2.5 parts of OK-500 matting powder;
17.5 parts of modified graphene suspension;
and B component:
and an isocyanate curing agent 19.
Example 1
A preparation method of a filler for a coating comprises the following treatment steps:
(1) Performing surface pretreatment on the conductive filler;
(2) Performing electrochemical purification treatment on the filler;
(3) Ultrasonic stripping;
(4) Repeating the step (2) and the step (3) for multiple times;
(5) Electrochemically grafting the double-bond-rich sulfonyl;
(6) And (5) post-treatment.
The conductive material is graphene, and the surface treatment process is as follows:
taking 300mg of commercially available graphene powder, placing the commercially available graphene powder in a three-neck flask containing a mixed solution of sulfuric acid and nitric acid, performing reflux treatment at 100 ℃ for 3 hours, naturally cooling, filtering, selecting a filter membrane used from a 0.45-micron meta-fluorine membrane, and washing to pH =5 to obtain a graphene suspension.
The electrochemical purification process is as follows: placing the graphene suspension obtained in the step (1) in an anode chamber of an electrolytic cell containing a diaphragm, stirring, and carrying out constant-current or constant-current electrochemical purification treatment by using a platinum sheet as an anode and a carbon rod as a cathode, wherein the constant voltage is as follows: 2V constant voltage treatment for 16 minutes; the temperature was 30 ℃ and the stirring speed was 800rpm.
And (3) ultrasonic stripping, namely closing the power supply of the electrolytic cell, opening the ultrasonic crusher, and placing an ultrasonic vibrating rod of the ultrasonic crusher in the anode chamber, wherein the ultrasonic frequency is 5000Hz, and the ultrasonic time is 1min.
And (5) repeating the step (4) for 5 times to obtain the purified graphene suspension.
Electrochemical grafting of double bond-rich sulfonyl:
1mmol of 4-methylbenzenesulfonylhydrazide was dissolved in a methanol solvent, and then 10wt% of tetrabutylammonium iodide, 5ml of saturated ammonium carbonate, 7g of a purified graphene suspension were added, and the pH was adjusted to 8 using potassium hydroxide under electrochemical conditions of 40mA for 4 hours at a temperature of 25 ℃.
The post-treatment process is as follows: filtering after full reaction, repeatedly washing with ethanol and acetone alternately, and ultrasonically dispersing the filtrate in deionized water containing surfactant to obtain the filler suspension for coating.
The mass ratio of the nitric acid to the sulfuric acid is 3: 1.
The coating filler suspension contained 15wt.% double bond rich sulfonyl-modified graphene, 1wt.% p123 surfactant and deionized water.
Example 2
A preparation method of a filler for a coating comprises the following processing steps:
(1) Performing surface pretreatment on the conductive filler;
(2) Performing electrochemical purification treatment on the filler;
(3) Ultrasonic stripping;
(4) Repeating the step (2) and the step (3) for multiple times;
(5) Electrochemically grafting the double-bond-rich sulfonyl;
(6) And (5) post-treatment.
The conductive material is graphene, and the surface treatment process is as follows:
350mg of commercially available graphene powder was put in a three-neck flask containing a mixed solution of sulfuric acid and nitric acid, and subjected to reflux treatment at 100 ℃ for 3.5 hours, after natural cooling, filtration was performed using a filter membrane selected from a 0.45 μm meta-fluorine membrane, and the membrane was washed to pH =5.5, thereby obtaining a graphene suspension.
The electrochemical purification process is as follows: and (2) placing the graphene suspension obtained in the step (1) in an anode chamber of an electrolytic cell containing a diaphragm, stirring, performing constant-current or constant-current electrochemical purification treatment by using a platinum sheet as an anode and a carbon rod as a cathode, applying 1.25 mA constant current for 18 minutes, wherein the temperature is 32.5 ℃, and the stirring speed is 850rpm.
Ultrasonic stripping, namely closing the power supply of the electrolytic cell, opening the ultrasonic crusher, and placing an ultrasonic vibrating rod of the ultrasonic crusher in the anode chamber, wherein the ultrasonic frequency is 5500Hz, and the ultrasonic time is 1.5min.
And (5) repeating the step (4) for 7 times to obtain the purified graphene suspension.
Electrochemically grafting the double-bond-rich sulfonyl group.
1.5mmol of 4-methylbenzenesulfonylhydrazide was dissolved in a methanol solvent, and 11.5wt% of tetrabutylammonium iodide, 7.5ml of saturated ammonium carbonate, 8.5g of a purified graphene suspension were added, and the pH was adjusted to 8.5 using potassium hydroxide under electrochemical conditions of 45mA for 4.5 hours at a temperature of 27.5 ℃.
The post-treatment process is as follows: filtering after full reaction, repeatedly washing with ethanol and acetone alternately, and ultrasonically dispersing the filtrate in deionized water containing surfactant to obtain the filler suspension for the coating.
The mass ratio of the nitric acid to the sulfuric acid is 3: 1.
The filler suspension for coating contained 17.5wt.% double bond-rich sulfonyl-modified graphene, 1.5 wt.% p123 surfactant, and deionized water.
Example 3
A preparation method of a filler for a coating comprises the following processing steps:
(1) Carrying out surface pretreatment on the conductive filler;
(2) Performing electrochemical purification treatment on the filler;
(3) Ultrasonic stripping;
(4) Repeating the step (2) and the step (3) for multiple times;
(5) Electrochemically grafting double-bond-rich sulfonyl;
(6) And (4) post-treatment.
The conductive material is graphene, and the surface treatment process comprises the following steps:
taking 400mg of commercially available graphene powder, placing the graphene powder in a three-neck flask containing a mixed solution of sulfuric acid and nitric acid, performing reflux treatment at 100 ℃ for 4 hours, naturally cooling, filtering, selecting a filter membrane with 0.45 mu m of a meta-fluorine membrane, and washing to pH =6 to obtain a graphene suspension.
The electrochemical purification process is as follows: placing the graphene suspension obtained in the step (1) in an anode chamber of an electrolytic cell containing a diaphragm, stirring, and carrying out constant-current or constant-current electrochemical purification treatment by using a platinum sheet as an anode and a carbon rod as a cathode, wherein the constant voltage is as follows: treating at 3V for 17 minutes at constant voltage; alternatively, 2mA of constant current was applied for 19 minutes at 35 ℃ with a stirring speed of 900rpm.
And (3) ultrasonic stripping, namely closing the power supply of the electrolytic cell, opening the ultrasonic crusher, and placing an ultrasonic vibrating rod of the ultrasonic crusher in the anode chamber, wherein the ultrasonic frequency is 6000Hz, and the ultrasonic time is 2min.
And (4) repeating the step (4) for 8 times to obtain the purified graphene suspension.
Electrochemical grafting double bond-rich sulfonyl:
2mmol 4-methylbenzenesulfonyl hydrazide is dissolved in a methanol solvent, and then 13wt% tetrabutylammonium iodide, 10ml of saturated ammonium carbonate, 10g of purified graphene suspension are added, and potassium hydroxide is used to adjust the pH to 9, the electrochemical conditions are 50mA, the time is 5h, and the temperature is 30 ℃.
The post-treatment process is as follows: filtering after full reaction, repeatedly washing with ethanol and acetone alternately, and ultrasonically dispersing the filtrate in deionized water containing surfactant to obtain the filler suspension for the coating.
The mass ratio of the nitric acid to the sulfuric acid is 3: 1.
The coating filler suspension contained 20wt.% double bond-rich sulfonyl-modified graphene, 2wt.% p123 surfactant, and deionized water.
Comparative example 1
The preparation method of the coating comprises the following steps: firstly, sequentially adding a hydroxyl acrylic resin dispersoid, a defoaming agent, a leveling agent, a dispersing agent, a film-forming assistant, a bactericide and a thickening agent into a stirring container containing water, stirring at 350rpm for 17.5min, then adding a pigment and a matting powder, increasing the stirring speed to 2150-2300 rpm, and the dispersing time to 55min, then adding a modified graphene suspension, stirring at 550rpm, and dispersing for 7.5min, standing in the shade to eliminate bubbles to obtain a component A, then adding a curing agent component B, stirring at 250rpm, adding a proper amount of water to dilute to construction viscosity, filtering with a 200-mesh filter cloth to obtain a two-component waterborne polyurethane coating, and then spraying the coating on the surface of a metal, wherein the coating can be made of stainless steel, aluminum alloy or other various metal materials, and the embodiment takes stainless steel as an example.
The coating composition obtained was as follows:
the component A comprises:
55 parts of a hydroxy acrylic resin dispersion;
0.25 part of BKY-024 defoaming agent;
0.35 part of BKY-348 leveling agent;
0.25 part of digao 760w dispersant;
1.75 parts of Texanol film-forming additive;
0.125 part of imidazole bactericide;
0.55 part of R-420 thickening agent;
17.5 parts of titanium dioxide pigment;
2.5 parts of OK-500 matting powder;
17.5 parts of modified graphene suspension;
and the component B comprises:
and an isocyanate curing agent 19.
The preparation process of the coating is completely consistent with the embodiment, and the difference is that the modified graphene suspension is only the graphene which is subjected to mixed acid pickling and purification treatment, and the subsequent electro-grafting treatment is not carried out.
Generally, the higher the Ecorr potential value, the better the corrosion resistance of the coating; the corrosion current density (icorr) shows the current corrosion state of the electrode, the smaller icorr value indicates the lower corrosion rate, and from the table above and the attached figure 7, the modified graphene-polyurethane composite coating material obtained by acidification, purification and electro-grafting treatment according to the present invention has the extremely high corrosion resistance, and compared with the comparative example 1, the electro-corrosion current density is reduced by two orders of magnitude. In addition, compared with the example 2 and the example 1, the effect of the constant current electric grafting is proved to be superior to the constant potential for a specific reason to be researched, and in addition, the appearance and appearance diagram of the purified graphene prepared by the example 2 of the invention is shown in the attached fig. 4 and the attached fig. 5, the dispersion degree is high, the number of graphene layers is small, no obvious stacking exists, and the suspension performance research of the electro-grafted graphene obtained by the example 2 and the comparative example 1 is shown in the attached fig. 6, the obvious delamination has occurred in the comparative example 1 after 15D sedimentation test, compared with the suspension obtained by the example 2, and no change is caused, the appearance and appearance of the modified graphene-polyurethane composite coating material prepared by the suspension obtained by the example 2 is shown in the attached fig. 2, and in addition, the SST result of the coating obtained by the example 2 is more than 480h when the neutral salt spray test is carried out on the stainless steel sheet, the polyurethane coating and the comparative example 1 and the example 2, and the SST result is shown in the attached fig. 3.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A preparation method of a filler for paint is characterized in that the filler is treated by the following steps:
(1) Carrying out surface pretreatment on the filler;
(2) Performing electrochemical purification treatment on the filler;
(3) Ultrasonic stripping;
(4) Repeating the step (2) and the step (3) for multiple times;
(5) Electrochemically grafting the double-bond-rich sulfonyl;
(6) Post-treatment;
wherein the filler is graphene, and the surface pretreatment process is as follows:
taking 300-400mg of commercially available graphene powder, placing the commercially available graphene powder in a three-neck flask containing a mixed solution of sulfuric acid and nitric acid, performing reflux treatment at 100 ℃ for 3-4h, naturally cooling, filtering, and washing until the pH =5-6 to obtain a graphene suspension;
the electrochemical purification treatment process comprises the following steps: placing the graphene suspension obtained in the step (1) in an anode chamber of an electrolytic cell containing a diaphragm, stirring, and carrying out constant-voltage or constant-current electrochemical purification treatment by using a platinum sheet as an anode and a carbon rod as a cathode, wherein the constant-voltage condition is as follows: 1.5-3V constant voltage treatment for 15-17 minutes; or applying 0.5-2mA constant current for 17-19 min at 30-35 deg.C and stirring speed of 800-900rpm;
turning off power supply of the electrolytic cell, turning on the ultrasonic crusher, placing ultrasonic vibrating rod of the ultrasonic crusher in the anode chamber, and performing ultrasonic treatment at 5000-6000Hz for 1-2min;
repeating the step (4) for 5-8 times to obtain a purified graphene suspension;
electrochemical grafting double-bond-rich sulfonyl treatment process:
dissolving 1-2mmol of 4-methylbenzenesulfonyl hydrazide in a methanol solvent, adding 10-13wt% of tetrabutylammonium iodide, 5-10ml of saturated ammonium carbonate solution and 7-10g of purified graphene suspension, adjusting the pH to 8-9 by using a potassium hydroxide solution, and carrying out electrochemical reaction under the conditions of 40-50mA for 4-5h at the temperature of 25-30 ℃;
the post-treatment process is as follows: filtering after full reaction, repeatedly and alternately washing with ethanol and acetone, and ultrasonically dispersing the filtrate in deionized water containing surfactant to obtain the suspension of the filler for the coating.
2. The method of claim 1, wherein the nitric acid and sulfuric acid are mixed at a mass ratio of 3: 1.
3. The method of claim 1, wherein the filtration membrane used in the step (1) is selected from 0.45 μm of a meta-fluoro membrane.
4. The method of claim 1, wherein the purified graphene suspension comprises 10-15% by weight of purified graphene.
5. The method for preparing the filler for coating according to claim 1, wherein the suspension of the filler for coating contains 15-20wt.% of the double bond-rich sulfonyl-modified graphene, 1-2 wt.% of the surfactant and deionized water.
6. The method of claim 5, wherein the surfactant is selected from the group consisting of P123 nonionic surfactants.
7. The method of claim 1, wherein the coating material is a two-component aqueous polyurethane coating material.
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