CN111500192A - Polysiloxane electrophoretic coating and preparation and application method thereof - Google Patents
Polysiloxane electrophoretic coating and preparation and application method thereof Download PDFInfo
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Abstract
The invention discloses a polysiloxane electrophoretic coating and a preparation and application method thereof, the polysiloxane electrophoretic coating is prepared by compounding functional pigment filler and auxiliary agent after hydrolytic polycondensation of silane coupling agent, the conductivity is 200-2000 mus/cm, the polysiloxane electrophoretic coating is deposited on the surface of a coated workpiece through an electrophoretic coating process, and then the polysiloxane electrophoretic coating is heated and cured to obtain a protective coating with thicker film layer and excellent performance. The polysiloxane electrophoretic coating mainly uses water as a solvent and is assisted by a high-boiling-point water-soluble organic solvent, has slow volatilization, small pollution and high electrophoretic coating efficiency, can be suitable for surface coating of metal parts, alloy metal parts and plastic parts with metal coatings on the surfaces to improve the performances of hardness, wear resistance, corrosion resistance, aging resistance and the like, and is easy to realize mechanical automatic operation, so the polysiloxane electrophoretic coating has wide application.
Description
Technical Field
The invention relates to a polysiloxane electrophoretic coating and a preparation and application method thereof, belonging to the field of coating and coating protection.
Background
Electrophoresis is used as a coating method, can deposit charged coating on the surface of a metal workpiece to form a uniform and compact film layer, has high coating utilization rate, can be suitable for workpieces with complex shapes, edges and corners and holes, is easy to realize mechanical automation in industrial coating, and has wide application in the fields of military industry, automobiles, electromechanics, household appliances and the like. Electrophoretic paints are classified into anodic electrophoretic paints (negatively charged) and cathodic electrophoretic paints (positively charged) according to the difference in charged charge of the resin. The resin of the anodic electrophoretic coating generally contains carboxyl groups, in the electrophoretic coating process, the coated workpiece is taken as an anode, the resin with the carboxyl groups moves to the anode, and the anode generates O through electrolytic reaction2And H+And H is+Reacts with the carboxyl groups to electrically deactivate the resin and deposit it on the anode workpiece. The cathodic electrophoretic coating resin generally has protonated amine group, in the electrophoretic coating process, the coated workpiece is taken as a cathode, the resin with amine group moves to the cathode, and the cathode is subjected to electrolytic reaction to generate H2And OH-And OH-Combine with the amine groups to form water, and cause the polymer to lose the electrical property and deposit on the cathode workpiece. At present, the research on the anodic electrophoretic coating is not much, and the research on the cathodic electrophoretic coating is more favored, because the anodic workpiece is easy to generate polarization corrosion and the generated oxygen is also easy to oxidize and discolor the polymer in the electrophoretic process.
The polysiloxane is a polymer with a main chain structure of '-Si-O-Si-' bond, is usually prepared by a hydrolytic polycondensation reaction of a silane coupling agent, has a series of advantages of good thermal stability, high hardness, corrosion resistance, aging resistance and the like, and is widely applied to the fields of corrosion resistance of metal surfaces, hardening and wear resistance of plastic surfaces, aging resistance and the like. The properties of the polysiloxane depend on the formulation of the silane coupling agent, the hydrolysis/polycondensation process and the coating method. Currently, the polysiloxane is mainly coated by dip coating, i.e. a workpiece is immersed in a polysiloxane solution and then slowly extracted, so that the prepared film has a loose structure, the thickness is only dozens to hundreds of nanometers, the protective performance is limited, too much polysiloxane is easily remained at the bottom end of the workpiece, and the coating is easy to crack during baking. In addition to dip coating, attempts have been made in recent years to produce polysiloxane film layers using electrochemically assisted deposition. The method is to electrically polymerize polysiloxane solution by using a coated metal sheet as a working electrode, so that polysiloxane is deposited and adsorbed on the surface of the metal sheet, and the preparation, curing and other processes of the polysiloxane solution are the same as those of the traditional method. Woo et al, who may first introduce an electrochemical assisted deposition means into the preparation of a silane film, found that the bonding force between the silane film obtained by this technique and the binder is significantly improved; in 1999, Mandlcr research group also used the electrochemical auxiliary technology to successfully deposit the polymethyl trimethoxy silane solution on the surfaces of conductive glass and gold, and in 2003, the research group of Mandlcr also used the technology for the protection treatment of the aluminum surface, and the result shows that the corrosion resistance of the silane film prepared by the electrochemical auxiliary deposition is obviously improved compared with the traditional dip coating method; van Ooij et al also deposited bis-1, 2- [ gamma- (triethoxy) silicopropyl ] tetrasulfide hydrolysate onto the aluminum alloy surface using an electrochemical assisted deposition technique, confirming that the electrochemical deposition method is beneficial to increasing the thickness, density and coverage rate of the polysiloxane film layer on the substrate. Although the electrochemical auxiliary deposition method has a positive effect on solving the problem of polysiloxane coating, the electrochemical auxiliary deposition method also has a plurality of defects, such as no electric charge of polysiloxane, incapability of migrating under the action of an electric field, electrolytic deposition only on the polysiloxane near an electrode, very low deposition efficiency, insufficient coating thickness, suitability for manufacturing small experimental samples, unsuitability for large-scale production, and the polysiloxane solution mainly takes alcohols (methanol, ethanol, isopropanol and the like) as solvents, is volatile, flammable and explosive and has low electric conductivity. Based on this, we need to develop new formulations and new coating methods of polysiloxane to realize its wide application in industrial fields.
Disclosure of Invention
The invention takes proper silane coupling agent as raw material, and the polysiloxane aqueous solution is synthesized through hydrolytic polycondensation reaction, then the polysiloxane aqueous solution is compounded with functional pigment, filler and auxiliary agent to prepare the high-conductivity electrophoretic coating, and then the electrophoretic coating is optimized through electrophoretic coating process, and is deposited on the surface of a coated workpiece, and after heating and curing, the polysiloxane protective coating with thicker film layer and excellent performance is obtained.
In order to realize the aim, the technical scheme of the invention is as follows:
the polysiloxane electrophoretic coating is characterized by being prepared by compounding a silane coupling agent with a functional pigment filler and an auxiliary agent after hydrolytic polycondensation, the conductivity is 200-2000 mu s/cm, and the coating formula is as follows (in percentage by weight):
in the polysiloxane electrophoretic coating, the silane coupling agent is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl-3-aminopropyl) methyldimethoxysilane, N- (2-aminoethyl-3-aminopropyl) trimethoxysilane, diethylenetriaminopropyltrimethoxysilane or 3-ureidopropyltrimethoxysilane, n-phenyl amino propyl trimethoxy silane, N-butyl amino propyl trimethoxy silane, bis- [3- (triethoxy silicon) propyl ] amine, bis- [3- (trimethoxy silicon) propyl ] ethylenediamine, ethyl triacetoxy silane and vinyl triacetoxy silane.
In the polysiloxane electrophoretic coating, the silane coupling agent is preferably one or more of bis- [3- (triethoxysilyl) propyl ] amine, bis- [3- (trimethoxysilyl) propyl ] ethylenediamine, diethylenetriaminopropyltrimethoxysilane, ethyltriacetoxysilane and vinyltriacetoxysilane;
in the polysiloxane electrophoretic coating, the sol nano material is SiO2Sol, ZrO2Sol, TiO2Sol, Al2O3One or more of the sol, pH value of 1-5, particle size of 5-50 nm and solid content of 5-50%。
In the polysiloxane electrophoretic coating, the sol nano material is preferably SiO2Sol, TiO2One or more sol, pH value of 2-5, particle size of 5-25 nm and solid content of 10-25%.
In the polysiloxane electrophoretic coating, the water-soluble organic solvent is one or more of methanol, ethanol, isopropanol, butanol, ethylene glycol methyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol butyl ether and acetylacetone.
In the polysiloxane electrophoretic paint, the water-soluble organic solvent is preferably one or more of isopropanol, butanol, ethylene glycol butyl ether, propylene glycol butyl ether and acetylacetone.
In the polysiloxane electrophoretic coating, the nano color paste is water-based nano color paste, the solid content is 5-30%, the granularity (D50) is less than or equal to 500nm, and the heat resistance is more than or equal to 120 ℃.
In the polysiloxane electrophoretic coating, the nano color paste is preferably water-based nano color paste, the solid content is 5-20%, the granularity (D50) is less than or equal to 250nm, and the heat resistance is more than or equal to 160 ℃;
in the polysiloxane electrophoretic coating, the polymer resin coating is one of epoxy electrophoretic paint, acrylic electrophoretic paint and polyurethane electrophoretic paint, the pH value is 4.0-6.5, the conductivity is 200-800 mu s/cm, and the solid content is 5-50%; the auxiliary agent is a surfactant.
The preparation and application method of the polysiloxane electrophoretic coating is characterized by comprising the following steps:
① weighing water, water-soluble organic solvent and sol nano material according to the formula, and stirring for 0.2-1.0 h at room temperature;
②, weighing one or more silane coupling agents according to the formula, stirring at room temperature for 0.0-4.0 h, slowly adding the silane coupling agents (30-60 drops/min) into the mixed solution obtained in the step ① by using a dropping funnel, and continuously stirring for reaction for 12.0-48.0 h, wherein the reaction temperature is 20.0-40.0 ℃;
③ adding the nanometer color paste, the polymer resin coating and the auxiliary agent into the product obtained in the step ②, and continuing stirring for 0.5-12.0 h to obtain the polysiloxane electrophoretic coating;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece as an electrode, and performing electrophoretic painting at an electrophoresis voltage of 20.0-400.0V for 20.0-360.0 seconds and at a construction temperature of 20.0-30.0 ℃;
⑤ taking out the coated workpiece from the electrophoresis tank, heating and curing at 80.0-200.0 deg.C for 0.2-48.0 h to obtain the polysiloxane protective coating.
In the preparation and application method of the polysiloxane electrophoretic coating, the coated workpiece is a metal part, a metal alloy part or a plastic part with a metal coating coated on the surface, the workpiece is used as a cathode in electrophoretic coating, and the pH value of the polysiloxane electrophoretic coating is 4.0-6.8; the thickness of the polysiloxane protective coating is 3-30 mu m, and the adhesive force is less than or equal to grade 1.
The principle of the invention is as follows: firstly, the polysiloxane solution is prepared by carrying out hydrolytic polycondensation on an amino silane coupling agent or compounding the amino silane coupling agent and an acetoxy silane coupling agent in an acidic environment, and the polysiloxane has positive charges, higher conductivity and good water solubility because amino groups can be protonated under the action of acid; secondly, the water-soluble and positively charged polysiloxane is taken as a film forming material to be compounded with functional pigment, filler and auxiliary agent, and the multicolor and multifunctional electrophoretic coating is developed by solving the problems of raw material matching, compatibility and synergistic enhancement; and finally, optimizing an electrophoretic coating process, depositing the polysiloxane electrophoretic coating on the surface of the coated workpiece, and heating and curing to form a polysiloxane protective coating so as to enhance the functions of the coated workpiece such as hardness, wear resistance, corrosion resistance, aging resistance and the like.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, a proper silane coupling agent is preferably selected, and after hydrolytic polycondensation, polysiloxane with positive charge is prepared, and the polysiloxane has high conductivity and good water solubility and meets the requirements of an electrophoretic coating process;
2. the polysiloxane coating is prepared by adopting an electrophoretic coating process, has uniform thickness, thicker film layer and excellent protective performance, and can overcome the defects of the prior technologies such as dip coating, electrochemical auxiliary deposition and the like;
3. the invention has strong innovativeness in formula design, selects the acidic sol as the filler, can provide an acidic environment to promote the hydrolytic polycondensation of the silane coupling agent, can be polymerized with the polysiloxane into a whole, realizes the molecular-level composition between the resin and the filler, and is greatly beneficial to preparing polysiloxane film layers with compact structure, wear resistance, high hardness, aging resistance and corrosion resistance; the nano color paste is selected as the pigment, the particle size is small, the transparency of the coating is not influenced, and the polysiloxane film is rich and colorful in appearance; the polymer resin coating is selected as an auxiliary reinforcing coating, so that the coating has an obvious effect on overcoming the defects of high hardness, poor flexibility and the like of a polysiloxane film layer;
4. the polysiloxane electrophoretic coating mainly uses water as a solvent and is assisted by a high-boiling-point water-soluble organic solvent, has slow volatilization, small pollution and high electrophoretic coating efficiency, can be suitable for coating the surfaces of large metal pieces, alloy metal pieces and plastic pieces with metal coatings on the surfaces, and is easy to realize mechanical automatic operation, so the polysiloxane electrophoretic coating has wide application.
Detailed Description
Example 1
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
bis- [3- (triethoxysilyl) propyl ] amine 8.0
Ethyltriacetoxysilane 2.0
Water 79.98
Propylene glycol butyl ether 10.0
Surfactant 0.02
The preparation and application method comprises the following steps:
① weighing water and propylene glycol butyl ether according to the formula, and stirring at room temperature for 0.2 h;
② weighing bis- [3- (triethoxysilyl) propyl ] amine and ethyltriacetoxysilane according to the formula, stirring at room temperature for 4.0h, slowly adding into the mixed solution of step ① (30 drops/min) by using a dropping funnel, and continuously stirring for reaction for 24.0h at 40.0 ℃;
③ adding nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) into ②, and stirring for 0.5h to obtain polysiloxane electrophoretic coating with pH of 6.5 and conductivity of 800 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece (aluminum piece) as a cathode, and carrying out electrophoretic coating at the voltage of 150.0V for 120.0 seconds and the construction temperature of 25.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 200.0 deg.C for 0.2h to obtain polysiloxane protective coating with thickness of 5 μm and adhesion of 0 grade.
Example 2
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
bis- [3- (trimethoxysilyl) propyl ] ethylenediamine 8
Vinyl triacetoxysilane 4
TiO2Sol 0.6
68.4 Water
Propylene glycol butyl ether 15.0
Acetylacetone 2.0
Nano violet 1.5
Surfactant 0.5
The preparation and application method comprises the following steps:
① weighing water, propylene glycol monobutyl ether, acetylacetone and TiO according to the formula2Sol (pH value 4.0, particle size 15.0nm, solid content 10%), stirring at room temperature for 0.4 h;
② weighing bis- [3- (trimethoxysilyl) propyl ] ethylenediamine and vinyl triacetoxysilane according to the formula, stirring at room temperature for 1.0h, slowly adding into the mixed solution of step ① (50 drops/min) by using a dropping funnel, and continuously stirring for reaction for 48.0h at the reaction temperature of 20.0 ℃;
③ adding nanometer purple (particle size (D50)250nm, solid content 15%, heat resistance 180 deg.C) and nonionic surfactant (polyoxyethylene octylphenol ether-10) into ② product, and stirring for 1.0h to obtain polysiloxane electrophoretic coating with pH of 5.5 and conductivity of 1200 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece (stainless steel workpiece) as a cathode, and carrying out electrophoretic coating at a voltage of 80.0V for 240.0 seconds and a construction temperature of 30.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 170.0 deg.C for 0.5h to obtain polysiloxane protective coating with thickness of 8 μm and adhesion of 0 grade.
Example 3
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
diethylenetriaminopropyltrimethoxysilane 5.0
ZrO2Sol 1.0
Al2O3Sol 1.0
Water 50.97
Isopropyl alcohol 20.0
Ethylene glycol butyl ether 20.0
Nanometer scarlet 2.0
Surfactant 0.03
The preparation and application method comprises the following steps:
① weighing water, isopropanol, ethylene glycol monobutyl ether and ZrO according to the formula2Sol (pH 2.0, particle size 10nm, solid content 10%), Al2O3Stirring the sol (pH value is 5.0, particle size is 20nm, solid content is 20%) at room temperature for 1.0 h;
② Diethylenetriaminopropyltrimethoxysilane is weighed according to the formula, stirred at room temperature for 0.0h, then slowly added into the mixed solution of step ① by using a dropping funnel (60 drops/min), and continuously stirred for reaction for 12.0h, wherein the reaction temperature is 25.0 ℃;
③ adding scarlet (particle size (D50) of 200nm, solid content of 20%, heat resistance of 200 deg.C) and nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) into ②, and stirring for 2.0 hr to obtain polysiloxane electrophoretic coating with pH of 6.8 and conductivity of 200 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking the coated workpiece (aluminum alloy) as a cathode, and carrying out electrophoretic painting at 40.0V for 360.0 seconds at 20.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 150.0 deg.C for 0.6h to obtain polysiloxane protective coating with thickness of 3 μm and adhesion of 0 grade.
Example 4
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
diethylenetriaminopropyltrimethoxysilane 9.0
Vinyltriacetoxysilane 6.0
TiO2Sol 0.2
Water 58.98
Butanol 25.0
Acetylacetone 1.0
0.5 nanometer Green
Surfactant 0.04
The preparation and application method comprises the following steps:
① weighing water, butanol, acetylacetone and TiO according to the formula2Sol (pH value 4.5, particle size 20.0nm, solid content 15%), stirring at room temperature for 0.3 h;
② Diethylenetriaminopropyltrimethoxysilane and vinyltriacetoxysilane are weighed according to the formula, stirred at room temperature for 2.0h, then slowly added into the mixed solution in step ① by using a dropping funnel, and stirred for reaction for 40.0h at the reaction temperature of 35.0 ℃;
③ adding nanometer green (particle size (D50)180nm, solid content 12%, heat resistance 160 deg.C) and nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) into ② product, and stirring at room temperature for 4.0 hr to obtain polysiloxane electrophoretic coating with pH of 4.0 and conductivity of 2000 μ s/cm;
④ adding the polysiloxane electrophoretic paint into an electrophoresis tank, taking the coated workpiece (magnesium alloy workpiece) as a cathode, and carrying out electrophoretic coating at 20.0V for 220.0 s at 25.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 140.0 deg.C for 0.8h to obtain polysiloxane protective coating with thickness of 10.0 μm and adhesion of 0 grade.
Example 5
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
bis- [3- (trimethoxysilyl) propyl ] ethylenediamine 8
Vinyl triacetoxysilane 3
TiO2Sol 0.5
68.2 Water
Propylene glycol butyl ether 15.0
Acrylic acid electrophoretic paint 5.0
Surfactant 0.3
The preparation and application method comprises the following steps:
① weighing water, propylene glycol monobutyl ether and TiO according to the formula2Sol (pH value 3.8, particle size 25.0nm, solid content 12%), stirring at room temperature for 0.5 h;
② weighing bis- [3- (trimethoxysilyl) propyl ] ethylenediamine and vinyl triacetoxysilane according to the formula, stirring at room temperature for 3.0h, slowly adding into the mixed solution of step ① (50 drops/min) by using a dropping funnel, and continuously stirring for reacting for 35.0h at 25.0 ℃;
③ adding acrylic acid electrophoretic paint (pH 4, conductivity 800 μ s/cm, solid content 5%) and cationic surfactant (cetyl trimethyl ammonium bromide) into the product of step ②, and stirring at room temperature for 12.0h to obtain polysiloxane electrophoretic paint, pH 5.0, conductivity 1600 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece (brass piece) as a cathode, and carrying out electrophoretic coating at 400.0V for 20.0 s at 27.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 175.0 deg.C for 0.5h to obtain polysiloxane protective coating with thickness of 25 μm and adhesion of grade 1.
Example 6
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
diethylenetriaminopropyltrimethoxysilane 7.0
Ethyltriacetoxysilane 3.0
SiO2Sol 0.5
TiO2Sol 0.5
Water 42.94
Isopropyl alcohol 20.0
Propylene glycol butyl ether 15.0
Nano black 1.0
Polyurethane electrophoretic paint 10.0
Surfactant 0.06
The preparation and application method comprises the following steps:
① weighing water, isopropanol, propylene glycol monobutyl ether and SiO according to the formula2Sol (pH 4.0, particle size 20nm, solid content 50%), TiO2Sol (pH value 2.0, particle size 5nm and solid content 10%), stirring at room temperature for 0.4 h;
② Diethylenetriaminopropyltrimethoxysilane and ethyltriacetoxysilane are weighed according to the formula, stirred at room temperature for 3.0h, then slowly added into the mixed solution in step ① by using a dropping funnel (40 drops/min), and continuously stirred for reaction for 36.0h, wherein the reaction temperature is 32.0 ℃;
③ adding 240nm of nano black (particle size (D50), 5% of solid content and 300 ℃ of heat resistance), a nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) and a polyurethane electrophoretic coating (pH 6.5, conductivity 200 mu s/cm and solid content 50%) into the product of the step ②, and continuously stirring for 10.0h at room temperature to obtain a polysiloxane electrophoretic coating, wherein the pH value is 4.5 and the conductivity is 1800 mu s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking the coated workpiece (aluminum alloy) as a cathode, and carrying out electrophoretic painting at the voltage of 200.0V for 200.0 seconds and the construction temperature of 22.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 180.0 deg.C for 0.4h to obtain polysiloxane protective coating with thickness of 20 μm and adhesion of 0 grade.
Example 7
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
the preparation and application method comprises the following steps:
① weighing water, isopropanol, butanol and SiO according to the formula2Sol (pH 4.5, particle size 50nm, solid content 25%), TiO2Sol gel(the pH value is 2.0, the particle size is 10nm, the solid content is 15%), and the mixture is stirred for 0.8h at room temperature;
② weighing bis- [3- (triethoxysilyl) propyl ] amine and ethyltriacetoxysilane according to the formula, stirring at room temperature for 2.5h, slowly adding into the mixed solution of step ① (55 drops/min) by using a dropping funnel, and continuously stirring for reacting for 40.0h at the reaction temperature of 30.0 ℃;
③ adding nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) and epoxy electrophoretic coating (pH 5, conductivity 600 μ s/cm, solid content 30%) into ②, and stirring at room temperature for 8.0h to obtain polysiloxane electrophoretic coating with pH 6.2 and conductivity 900 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece (hot-dip galvanized workpiece) as a cathode, and carrying out electrophoretic coating at the voltage of 250.0V for 60.0 seconds and the construction temperature of 25.0 ℃;
⑤ taking out the workpiece from the electrophoresis tank, heating and curing at 160.0 deg.C for 0.8h to obtain polysiloxane protective coating with thickness of 30 μm and adhesion of 0 grade.
Example 8
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
the preparation and application method comprises the following steps:
① weighing water, isopropanol, butanol and TiO according to the formula2Sol (pH value 2.5, particle size 30nm and solid content 5%), stirring at room temperature for 0.8 h;
② weighing bis- [3- (triethoxysilyl) propyl ] amine and ethyltriacetoxysilane according to the formula, stirring at room temperature for 2.5h, slowly adding into the mixed solution of step ① (55 drops/min) by using a dropping funnel, and continuously stirring for reacting for 40.0h at the reaction temperature of 30.0 ℃;
③ adding nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) into ②, stirring at room temperature for 1.5 hr to obtain polysiloxane electrophoretic coating with pH of 6.0 and conductivity of 700 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece (a polycarbonate workpiece with a nickel plating layer) as a cathode, and carrying out electrophoretic painting at the voltage of 160.0V for 150.0 seconds and the construction temperature of 24.0 ℃;
⑤ taking the workpiece out of the electrophoresis tank, heating and curing at 100.0 deg.C for 24.0h to obtain polysiloxane protective coating with thickness of 9 μm and adhesion of grade 1.
Example 9
The polysiloxane electrophoretic coating has the following formula (in percentage by weight):
the preparation and application method comprises the following steps:
① weighing water, propylene glycol monobutyl ether, acetylacetone and TiO according to the formula2Sol (pH value 1.0, particle size 10nm and solid content 12%), stirring at room temperature for 0.6 h;
② weighing bis- [3- (triethoxysilyl) propyl ] amine and vinyl triacetoxysilane according to the formula, stirring at room temperature for 3.5h, slowly adding into the mixed solution of step ① (35 drops/min) by using a dropping funnel, and continuously stirring for reacting for 38.0h at 32.0 ℃;
③ adding nonionic surfactant (DuPont FSO-100 fluorocarbon surfactant) into ②, stirring at room temperature for 3.0h to obtain polysiloxane electrophoretic coating with pH of 6.3 and conductivity of 1000 μ s/cm;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece (PMMA (polymethyl methacrylate) with a chromium coating layer) as a cathode, and performing electrophoretic coating at the voltage of 120.0V for 120.0 seconds and the construction temperature of 26.0 ℃;
⑤ taking the coated workpiece out of the electrophoresis tank, heating and curing at 80.0 deg.C for 48.0h to obtain polysiloxane protective coating with thickness of 5 μm and adhesion of grade 1.
Comparative embodiment
The following comparative examples were all set up on the basis of example 2 in the above case.
Comparative example 1
The polysiloxane electrophoretic coating prepared in example 2 is applied by a dip coating process, and the coating thickness is 0.2 μm and the adhesion force cannot be detected as in example 2.
Comparative example 2
The polysiloxane electrophoretic coating prepared in example 2 is applied by an electrochemical assisted deposition method, and the construction is otherwise the same as example 2, wherein the coating thickness is 2.0 μm, and the adhesive force is 0 grade.
Comparative example 3
The "bis- [3- (trimethoxysilyl) propyl ] ethylenediamine 8, vinyltriacetoxysilane 4, and water 68.4" in example 2 was changed to "bis- [3- (trimethoxysilyl) propyl ] ethylenediamine 12, vinyltriacetoxysilane 6, and water 62.4", and the silicone electrodeposition coating was unstable and gel-prone, as in example 2.
Comparative example 4
The "bis- [3- (trimethoxysilyl) propyl ] ethylenediamine 8, vinyltriacetoxysilane 4, and water 68.4" in example 2 were changed to "bis- [3- (trimethoxysilyl) propyl ] ethylenediamine 2, vinyltriacetoxysilane 1, and water 77.4" in example 2, except that the coating thickness was 2 μm, and the adhesion was rated 0.
Comparative example 5
The electrophoretic coating voltage of 80.0V for 240.0 seconds in example 2 was changed to electrophoretic coating voltage of 15.0V for 360.0 seconds, which is otherwise the same as example 2, with a coating thickness of 0.5 μm and an adhesion level of 0.
Comparative example 6
The electrophoretic coating voltage of 80.0V for 240.0 seconds in example 2 was changed to electrophoretic coating voltage of 80.0V for 10.0 seconds, which is otherwise the same as example 2, with a coating thickness of 0.5 μm and an adhesion level of 0.
Comparative example 7
The electrophoretic coating, voltage 80.0V and time 240.0 s in example 2 were changed to electrophoretic coating, voltage 80.0V and time 400.0 s, which is otherwise the same as example 2, and the coating thickness was 10 μm, the adhesion was of level 0, and pores were left on the coating surface.
Comparative example 8
The electrophoretic coating, voltage of 450.0V and time of 360.0 seconds in example 2 was changed to electrophoretic coating, thickness of 10 μm, adhesion of 1 grade and cracks remained on the surface of the coating, as in example 2.
As can be seen from comparative examples 1-2, the thickness of the polysiloxane film layer prepared by the traditional dipping method and the electrochemical auxiliary deposition method is not as thick as that of the electrophoretic coating method of the invention; as can be seen from comparative examples 3-4, the formula proportion of the silane coupling agent has obvious influence on the coating thickness, the adhesive force and other properties; from comparative examples 5 to 8, it can be seen that the electrophoretic coating process of the present invention has a key effect on the coating thickness, adhesion, and other properties.
Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (9)
1. The polysiloxane electrophoretic coating is characterized by being prepared by compounding a silane coupling agent with a functional pigment filler and an auxiliary agent after hydrolytic polycondensation, the conductivity is 200-2000 mu s/cm, and the coating formula is as follows (in percentage by weight):
2. the electrophoretic polysiloxane coating according to claim 1, wherein the silane coupling agent is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl-3-aminopropyl) methyldimethoxysilane, N- (2-aminoethyl-3-aminopropyl) trimethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, N-butylaminopropyltrimethoxysilane, bis- [3- (triethoxysilyl) propyl ] amine, bis- [3- (trimethoxysilyl) propyl ] ethylenediamine, ethyltriacetoxysilane, N-butylaminopropyltrimethoxysilane, bis- [3- (triethoxysilyl) propyl ] amine, N-butylaminopropyltrimethoxysilane, bis, One or more of vinyltriacetoxysilanes.
3. The polysiloxane electrophoretic coating according to claim 1, wherein the sol nanomaterial is SiO2Sol, ZrO2Sol, TiO2Sol, Al2O3One or more of the sol, pH value of 1-5, particle size of 5-50 nm and solid content of 5-50%.
4. The polysiloxane electrophoretic paint according to claim 1, wherein the water-soluble organic solvent is one or more of methanol, ethanol, isopropanol, butanol, ethylene glycol methyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol butyl ether, and acetylacetone.
5. The polysiloxane electrophoretic coating according to claim 1, wherein the nano color paste is an aqueous nano color paste, the solid content is 5-30%, the particle size (D50) is less than or equal to 500nm, and the heat resistance is more than or equal to 120 ℃.
6. The polysiloxane electrophoretic coating according to claim 1, wherein the polymer resin coating is one of epoxy electrophoretic coating, acrylic electrophoretic coating and polyurethane electrophoretic coating, and has a pH value of 4.0-6.5, an electrical conductivity of 200-800 μ s/cm, and a solid content of 5-50%; the auxiliary agent is a surfactant.
7. The preparation and application method of the polysiloxane electrophoretic coating is characterized by comprising the following steps:
① weighing water, water-soluble organic solvent and sol nano material according to the formula, and stirring for 0.2-1.0 h at room temperature;
②, weighing one or more silane coupling agents according to the formula, stirring at room temperature for 0.0-4.0 h, slowly adding the silane coupling agents (30-60 drops/min) into the mixed solution obtained in the step ① by using a dropping funnel, and continuously stirring for reaction for 12.0-48.0 h, wherein the reaction temperature is 20.0-40.0 ℃;
③ adding the nanometer color paste, the polymer resin coating and the auxiliary agent into the product obtained in the step ②, and continuing stirring for 0.5-12.0 h to obtain the polysiloxane electrophoretic coating;
④ adding polysiloxane electrophoretic paint into an electrophoresis tank, taking a coated workpiece as an electrode, and performing electrophoretic painting at an electrophoresis voltage of 20.0-400.0V for 20.0-360.0 seconds and at a construction temperature of 20.0-30.0 ℃;
⑤ taking out the coated workpiece from the electrophoresis tank, heating and curing at 80.0-200.0 deg.C for 0.2-48.0 h to obtain the polysiloxane protective coating.
8. The method for preparing and applying the polysiloxane electrophoretic coating according to claim 7, wherein the workpiece to be coated is a metal part, a metal alloy part or a plastic part coated with a metal coating on the surface, and is used as a cathode in electrophoretic coating.
9. The preparation and application method of the polysiloxane electrophoretic coating according to claim 7, wherein the pH value of the polysiloxane electrophoretic coating is 4.0-6.8; the thickness of the polysiloxane protective coating is 3-30 mu m, and the adhesive force is less than or equal to grade 1.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102206848A (en) * | 2011-01-23 | 2011-10-05 | 浙江大学 | Cathode electrophoresis protective coating modified by silicane and application thereof |
| CN109338430A (en) * | 2018-09-10 | 2019-02-15 | 常州大学 | A kind of preparation method of the silane being covered on metal surface/epoxy resin-GO- silane multilayer proofing film |
| CN110396360A (en) * | 2019-06-27 | 2019-11-01 | 河北晨阳工贸集团有限公司 | A kind of cathode electrophoresis dope and preparation method thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102206848A (en) * | 2011-01-23 | 2011-10-05 | 浙江大学 | Cathode electrophoresis protective coating modified by silicane and application thereof |
| CN109338430A (en) * | 2018-09-10 | 2019-02-15 | 常州大学 | A kind of preparation method of the silane being covered on metal surface/epoxy resin-GO- silane multilayer proofing film |
| CN110396360A (en) * | 2019-06-27 | 2019-11-01 | 河北晨阳工贸集团有限公司 | A kind of cathode electrophoresis dope and preparation method thereof |
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Application publication date: 20200807 |