CN112126332B - Aqueous coating composition - Google Patents
Aqueous coating composition Download PDFInfo
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- CN112126332B CN112126332B CN202011000144.9A CN202011000144A CN112126332B CN 112126332 B CN112126332 B CN 112126332B CN 202011000144 A CN202011000144 A CN 202011000144A CN 112126332 B CN112126332 B CN 112126332B
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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
- 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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- C—CHEMISTRY; METALLURGY
- 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
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/20—Diluents or solvents
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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
- 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
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/60—Additives non-macromolecular
- C09D7/61—Additives non-macromolecular inorganic
- C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
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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
- 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
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/65—Additives macromolecular
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/02—Elements
- C08K3/08—Metals
- C08K2003/0812—Aluminium
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Abstract
The invention discloses a water-based paint composition, which comprises a film-forming resin, an amino resin, a pigment and an organic solvent, wherein the film-forming resin comprises a polycarbonate-based polyurethane resin. Also disclosed is the use of the aqueous coating composition for coating a substrate and substrates coated with the aqueous coating composition.
Description
Technical Field
The invention relates to the field of coatings, in particular to an automobile coating, and especially relates to a finish paint for automobile hubs.
Background
The finish paint for automobile hubs in the current market mainly takes solvent-based paint as a main material. Generally, the solvent-based finish paint is mainly prepared from resin, aluminum powder, an organic solvent, an auxiliary agent and the like. Such solvent-based finishes provide the automobile hub with excellent appearance, such as a shiny metallic finish with a smooth, dense coating. However, solvent-based coatings suffer from low lightning, flammability, and high VOC emissions.
Therefore, in order to meet the requirements of safety and environmental regulations on VOC, there is an urgent practical need to develop a coating for water-based automobile wheel hubs. Meanwhile, the water-based paint also has the advantages of excellent appearance, high adhesive force, good water resistance and the like so as to meet the application requirements of the paint for automobile hubs.
Disclosure of Invention
The present inventors have conducted extensive studies and developed an aqueous coating composition having a low VOC content, excellent appearance, high substrate adhesion, good water resistance and the like.
In one aspect, the present invention provides an aqueous coating composition comprising a film-forming resin, an amino resin, a pigment, and an organic solvent, wherein the film-forming resin comprises a polycarbonate-based polyurethane resin.
In another aspect, the present invention provides the use of an aqueous coating composition for coating a substrate, wherein the aqueous coating composition comprises a film-forming resin, an amino resin, a pigment and an organic solvent, wherein the film-forming resin comprises a polycarbonate-based polyurethane resin.
In yet another aspect, the present disclosure provides a coated substrate comprising at least one coating layer formed from an aqueous coating composition, wherein the aqueous coating composition comprises a film-forming resin, an amino resin, a pigment, and an organic solvent, wherein the film-forming resin comprises a polycarbonate-based polyurethane resin.
The features and advantages of the present invention will be presented in more detail in the following detailed description of the embodiments.
Detailed Description
Other than in the examples, or where otherwise explicitly indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently has certain errors. This error is a corollary to the standard deviation found in its corresponding measurement method.
Moreover, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.
In this application, the use of the singular includes the plural and plural encompasses singular, unless expressly stated otherwise. In addition, in this application, the use of "or" means "and/or" unless explicitly stated otherwise, even though "and/or" may be explicitly used in some cases. In addition, in this application, the use of "a" means "at least one" unless explicitly stated otherwise. For example, "a" polymer, "a" coating, and the like refer to one or more of any of these items. And features of one embodiment may be used with other embodiments as will be recognized by those skilled in the art, even if not explicitly stated herein.
The aqueous coating composition according to the invention can be used as a top coat, suitable for coating metal substrates, such as automobile hubs. As used herein, the term "aqueous" refers to a coating composition that includes at least 50 wt% water in a solvent. As used herein, the "topcoat" refers to a coating that is deposited over another coating, such as a primer, to provide a protective and/or decorative layer.
The coating composition according to the invention is a coating composition having a low VOC content. As used herein, the term "VOC (volatile organic compound)" refers to any organic compound having a boiling point of less than or equal to 250 ℃ (482 ° f) measured at standard atmospheric pressure of 101.3 kPa. Organic solvents are typically the major source of VOCs. The VOC content (free of water) of the aqueous coating composition according to the invention is lower than 420g/L, which meets the requirements of new national environmental regulations on the VOC content of aqueous coatings. The VOC value can be obtained by detecting the contents of the respective organic compound components in the paint by gas chromatography and then adding the contents of the respective components.
The coating composition according to the present invention has excellent appearance. Herein, the appearance of the coating is evaluated by the technical indicators of yellowing at high temperature, aluminum powder orientation. The "yellowing at high temperature" refers to a change in color, specifically, degree of yellowing, of a coating layer formed from the coating composition according to the present invention after being left at a certain high temperature for a certain time, such as at least 120 ℃ for more than 20 minutes. Herein, the color of the coating layer is determined based on the laa b color system specified in JIS Z8729. In the text, when the single-angle color difference Δ b of the coating formed from the coating composition is less than 0.5, yellowing at high temperature is not considered to occur; on the contrary, yellowing at high temperature is considered to occur.
The coating composition according to the present invention has excellent compatibility, and it can be used in combination with a powder coating or a liquid coating. In other words, the coating composition according to the invention can be applied as a top coat between a powder primer and a powder clear coat. Or alternatively, the coating composition according to the invention may be applied as a top coat, between a liquid primer and a liquid clear coat. In this context, the compatibility of a coating with a powder paint or with a liquid paint is evaluated by determining the level of adhesion between the coatings. The coating composition according to the invention has good interlayer adhesion with the powder base/varnish and with the liquid base/varnish.
The aqueous coating composition according to the present invention has excellent recoatability. As used herein, the term "recoatability" refers to the ease of repeated coating with the same coating material and the quality of the resulting coating. Herein, "recoatability" is reflected in "recoat adhesion", i.e., the magnitude of adhesion of the coating after recoat is tested.
The aqueous coating composition according to the present invention has excellent water resistance. As used herein, the term "water resistance" refers to the ability of a coating to resist water, i.e., not to wrinkle or peel off after immersion. Herein, the water resistance of the coating is evaluated by determining the "adhesion" of the coating after soaking.
The aqueous coating composition according to the present invention has excellent moisture resistance. As used herein, the term "moisture resistance" refers to the ability of a coating to maintain constant properties in a humid environment. Herein, the moisture resistance of a coating is evaluated by determining the "adhesion" of the coating in a humid environment.
The aqueous coating composition according to the invention has excellent stability. In this context, the term "stability" means the heat storage stability, i.e. the viscosity of the aqueous coating composition according to the invention does not change and does not gel after a period of 30 days at 50 ℃.
The aqueous coating composition according to the present invention has a wide operating window. That is, the aqueous coating composition according to the present invention can be cured over a wide period of time at a wide range of operating temperatures, while the properties of the formed coating are equally excellent.
The water-based finish paint composition is a one-component paint composition. The single-component coating is a single-package coating and has the advantages of being ready to use and convenient to store and construct.
The coating composition according to the present invention is a thermosetting coating composition, i.e., the coating composition is cured to a film by heating after being applied to a substrate surface. As used herein, the term "cure" refers to the process of a material becoming "fixed" to form an irreversible crosslinked network, no longer flowing, melting, or dissolving. The term "curing" is used interchangeably herein with "crosslinking".
The coating composition according to the invention is a low solids coating composition. As used herein, the term "low solids" refers to a coating composition having a low mass fraction of dry components relative to all components in the coating, for example no more than about 15 wt%, such as no more than about 10 wt%.
In one aspect, the present invention provides an aqueous coating composition comprising a film-forming resin comprising a polycarbonate-based polyurethane resin, an amino resin, a pigment, and an organic solvent.
The polycarbonate-based polyurethane resin suitable for the aqueous coating composition of the present invention means a polymer resin including a urethane-based repeating unit and a carbonate-based repeating unit. Suitably, the polycarbonate-based polyurethane resin used in the present invention can be obtained by using an aliphatic polycarbonate diol as a raw material. In some embodiments, the polycarbonate-based polyurethane resin suitable for use in the aqueous coating composition of the present invention is in the form of a dispersion having a solids content of about 25 to 50 wt.%, such as 30 to 40 wt.%. The "solids content" refers to the mass remaining after evaporation of the solution as a percentage of the mass of the original dispersion.
Suitably, the polycarbonate-based polyurethane resin used in the aqueous coating composition of the present invention has a stretch of at least about 180%, for example about 210%. Suitably, the polycarbonate-based polyurethane resin used in the aqueous coating composition of the present invention has a tensile strength of at least about 5100psi, for example at least about 5800psi, such as about 6800 psi.
Polycarbonate-based polyurethane resins suitable for use in the aqueous coating compositions of the present invention are commercially available. Commercial examples of suitable polycarbonate-based polyurethane resins include, but are not limited to, polycarbonate-based polyurethane resins from Hauthaway.
Typically, the aqueous coating composition according to the invention comprises at least about 0.6 wt%, suitably at least about 1.0 wt%, such as at least about 1.5 wt%, and up to about 8.0 wt%, suitably up to about 7.0 wt%, for example up to about 6.0 wt%, of a polycarbonate-based polyurethane resin, based on the total weight of the coating composition.
In some embodiments, the film-forming resin in the aqueous coating composition according to the present invention may also include a polyester resin.
The amino resin in the aqueous coating composition according to the present invention can be cross-linked and fixed with the above film-forming resin (such as a polycarbonate-based polyurethane resin) to form an irreversible network structure. Suitably, the amino resin used in the aqueous coating composition of the present invention comprises a methylated amino resin. The methylated amino resin is obtained by carrying out etherification reaction on amino resin by using methanol as an etherifying agent.
Suitably, the amino resin used in the aqueous coating composition of the present invention comprises a fully methylated amino resin and/or a partially methylated amino resin. Suitably, the amino resin used in the aqueous coating composition of the present invention contains alkoxymethyl, hydroxymethyl and imino groups. In some embodiments, the amino resin used in the aqueous coating composition of the present invention contains up to about 15 mol% imino groups, for example up to about 12 mol% imino groups, such as up to about 8 mol% imino groups. In some embodiments, the amino resin used in the aqueous coating composition of the present invention contains up to about 10 mol% methylol groups, suitably up to about 7 mol% methylol groups, for example up to about 5 mol% methylol groups. In some embodiments, the amino resin used in the aqueous coating composition of the present invention contains at least about 65 mol% of alkoxymethyl groups, suitably at least about 70 mol% of alkoxymethyl groups, such as at least about 80 mol% of alkoxymethyl groups. In some embodiments, the amino resin used in the aqueous coating composition of the present invention is a fully methylated amino resin.
Amino resins suitable for use in the aqueous coating composition of the present invention are commercially available. Examples of suitable amino resins include, but are not limited to, amino resins from Intel corporation (INEOS).
Typically, the aqueous coating composition according to the invention comprises at least about 0.2 wt%, suitably at least about 0.5 wt%, and up to about 2.5 wt%, for example up to about 2.0 wt%, of the amino resin, based on the total weight of the coating composition.
Generally, the weight ratio of the polycarbonate-based polyurethane resin and the amino resin used in the aqueous coating composition of the present invention is about 2 to 4:1, suitably about 2.5 to 3.5: 1.
the pigment used in the aqueous coating composition according to the present invention includes aluminum powder. Suitably, the aluminium powder used in the aqueous coating composition of the present invention comprises fumed silica coated aluminium powder. The aluminum powder has the advantages of good water resistance, good stability and long storage period.
In some embodiments, the aluminum powder suitable for use in the aqueous coating composition of the present invention is in the form of an aluminum powder slurry, wherein the aluminum powder content is 35 to 50 wt%, such as 43 to 47 wt%. In some embodiments, the aluminum powder suitable for use in the aqueous coating composition of the present invention is in the form of an aluminum powder slurry, wherein the content of the aluminum powder is 10 to 20 wt%.
Typically, the aqueous coating composition according to the invention comprises at least about 0.1 wt.%, suitably at least about 0.3 wt.%, and up to about 2.0 wt.%, for example up to about 1.5 wt.% of aluminum powder, based on the total weight of the coating composition.
Aluminum powder suitable for use in the aqueous coating composition of the present invention is commercially available. Examples of suitable aluminum powders include, but are not limited to, aluminum powders from alcay (Eckart), the eastern aluminum industry (Toyo aluminum K.K.), and the like.
In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the invention is at least about 0.04, suitably at least about 0.06, such as at least about 0.10. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the invention is at most about 0.20, suitably at most about 0.18, such as at most about 0.16.
In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.04. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.05. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.06. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.07. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.08. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.09. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.10. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.11. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.12. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.13. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.14. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.15. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.16. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.17. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.18. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.19. In some embodiments, the weight ratio of pigment to the sum of film-forming resin and amino resin in the aqueous coating composition according to the present invention may be about 0.20.
The organic solvent used in the aqueous coating composition according to the present invention may include one or more selected from the group consisting of: aliphatic or aromatic hydrocarbons such as toluene, xylene, alcohols such as butanol, isopropanol and 2-butoxyethanol, esters such as n-butyl acetate, ethylene glycol butyl ether acetate, diethylene glycol butyl ether, propylene glycol methyl ether acetate and butyl glycol acetate, ketones such as acetone, methyl n-amyl ketone, alcohol ethers such as ethylene glycol butyl ether, ethylene glycol hexyl ether and dipropylene glycol methyl ether, and the like. Suitably, the organic solvents used in the aqueous coating composition of the present invention include alcohols and alcohol ether based solvents. In some embodiments, the organic solvent used in the waterborne coating compositions of the present invention includes isopropyl alcohol, ethylene glycol butyl ether, ethylene glycol hexyl ether, and dipropylene glycol methyl ether. Suitably, the weight ratio of isopropanol, ethylene glycol butyl ether, ethylene glycol hexyl ether and dipropylene glycol methyl ether in the organic solvent is from about 1.5-3.5: 8-11: 2-3.5: 1-2.5.
Generally, the aqueous coating composition according to the present invention includes 10 to 35 wt% of an organic solvent based on the total weight of the coating composition.
The aqueous coating composition according to the present invention may further include 50 to 85 wt% of water based on the total weight of the coating composition.
The aqueous coating composition according to the invention may also comprise a wetting dispersant. The wetting and dispersing agent can improve the surface tension and permeability of the coating composition, can better wet a substrate, and can promote the compatibility of the components in the coating composition. Wetting dispersants suitable for use in the aqueous coating compositions of the present invention are commercially available. Examples of suitable wetting dispersants include, but are not limited to, those from basf, BYK, eastman. Typically, the waterborne top coat composition according to the present invention comprises 0 to 1 wt% of wetting dispersant based on the total weight of the coating composition.
The coating composition according to the present invention may also include one or more other auxiliary ingredients including, but not limited to, defoamers that inhibit the formation of foam in the coating composition; fragrances that provide a pleasant odor to the coating; preservatives that can protect the coating from mold; a pH adjuster for controlling pH and stabilizing the coating; waxes to improve scratch resistance and improve tactile sensation; thickeners to increase the viscosity of the coating and improve the wet film thickness and protect the coating from settling and delamination, and the like. When present, each auxiliary component is present in an amount of up to about 1 wt%, based on the total weight of the coating composition.
The aqueous coating composition according to the invention can be prepared according to the following process comprising: (1) adding the film-forming resin and a part of water into a reactor, and stirring at a high speed for 10-20 minutes; (2) adding a wetting dispersant and a part of solvent into a reactor, and stirring at a medium speed for 5-10 minutes; (3) adding the amino resin, the pigment and the residual solvent into a reactor, and stirring at a high speed for about 10 minutes; (4) the remaining water was added to the reactor.
In another aspect, the present invention provides the use of an aqueous coating composition for coating a substrate, wherein the aqueous coating composition comprises a film-forming resin comprising a polycarbonate-based polyurethane resin, an amino resin, a pigment and an organic solvent.
In yet another aspect, the present disclosure provides a coated substrate comprising at least one coating layer formed from an aqueous coating composition, wherein the aqueous coating composition comprises a film-forming resin comprising a polycarbonate-based polyurethane resin, an amino resin, a pigment, and an organic solvent.
The aqueous coating composition of the present invention can be applied by any standard method known in the art, such as electrocoating, spraying, dipping, roll coating, brush coating, and the like, and then cured under heating to form a coating. Generally, the water-based paint composition is cured for 20 to 50 minutes under the temperature condition of 120 to 190 ℃. The coating composition of the present invention may be applied to a thickness of 1 to 20 microns, such as 2 to 5 microns.
The aqueous coating composition according to the present invention can be applied to various metal substrates, such as automobile hubs.
In yet another aspect, the present invention provides a coating system comprising a first coating composition, a second coating composition, and a third coating composition, wherein the second coating composition is the above-described aqueous coating composition.
In some embodiments, the first coating composition is a powder primer composition. In some embodiments, the third coating composition is a powder varnish composition. In some embodiments, the first coating composition is a liquid primer composition. In some embodiments, the third coating composition is a liquid varnish composition.
Examples
The following examples are provided to further illustrate the invention but are not to be construed as limiting the invention to the details set forth in the examples. All parts and percentages in the following examples are by weight unless otherwise indicated.
Preparation of the aqueous coating composition according to the invention
The waterborne coating composition Ex1-3 provided by the present invention was prepared using the components and contents listed in table 1 below, with the specific steps: (1) adding the film-forming resin and a part of water into a reactor, and stirring at a high speed for 10-20 minutes; (2) adding a wetting dispersant and a part of solvent into a reactor, and stirring at a medium speed for 5-10 minutes; (3) adding the amino resin, the pigment and the residual solvent into a reactor, and stirring at a high speed for about 10 minutes; (4) the remaining water was added to the reactor.
TABLE 1 waterborne coating composition Ex1-3 according to the invention
aA polycarbonate-based polyurethane resin having a tensile elongation of at least about 180% and a tensile strength of at least about 5100psi, dispersed in dipropylene glycol dimethyl ether at a solids content of about 30-40 wt%;
bpartially and/or fully methylated amino resin dispersions having a solids content of about 80-92% from the Invitrogen (INEOS);
c1the aluminum powder slurry coated by the fumed silica has a solid content of about 43-47 wt% and comes from Eika (Eckart);
c2the aluminum powder slurry coated by the fumed silica has a solid content of about 10-20 wt% and comes from Eika (Eckart);
dfrom BYK;
ea combination of isopropyl alcohol, butyl cellosolve, hexyl cellosolve and dipropylene glycol methyl ether in a weight ratio of about 1.5-3.5: 8-11: 2-3.5: 1-2.5.
Preparation of comparative coating compositions
(1) Comparative coating composition CE1-4 with different resin systems
A comparative coating composition CE1-4 was prepared using the components and levels listed in table 2 below, with the following steps: (1) adding the film-forming resin and a part of water into a reactor, and stirring at a high speed for 10-20 minutes; (2) adding a wetting dispersant and a part of solvent into a reactor, and stirring at a medium speed for 5-10 minutes; (3) adding the amino resin, the pigment and the residual solvent into a reactor, and stirring at a high speed for about 10 minutes; (4) the remaining water was added to the reactor.
TABLE 2 comparative coating composition CE1-4
a1An acrylic resin dispersion having a core-shell structure, a solid content of about 20 to 30 wt%, a hydroxyl value of up to about 35mg KOH/g, and an acid value of about 10 to 30mg KOH/g;
a2the water-based polyester type polyurethane resin dispersion has a solid content of about 35-45 wt%, and can be prepared from the following components: isophthalic acid, neopentyl glycol, trimethylolpropane, diisocyanate, etc.;
a3the acrylic resin emulsion has a core-shell structure, the solid content is about 30-40 wt%, and the weight-average molecular weight is about 210000-250000;
a4a polycarbonate-based polyurethane resin having a tensile elongation of at least about 180% and a tensile strength of at least about 5100psi, dispersed in dipropylene glycol dimethyl ether at a solids content of about 30-40 wt%;
b1partially and/or fully methylated amino resin dispersions having a solids content of about 80-92% from the Invitrogen (INEOS);
b2high imino butylated amino resin dispersions with a solids content of about 80-90% from the Intel Propionian (INEOS);
cthe aluminum powder slurry coated by the fumed silica has a solid content of about 43-47 wt% and comes from Eika (Eckart);
dfrom BYK;
ea combination of isopropyl alcohol, butyl cellosolve, hexyl cellosolve and dipropylene glycol methyl ether in a weight ratio of about 1.5-3.5: 8-11: 2-3.5: 1-2.5.
(2) Comparison coating composition CE5-8 with different content ratios
Comparative coating compositions CE5-8 were prepared using the components and levels listed in table 3 below, with the specific steps: (1) adding the film-forming resin and a part of water into a reactor, and stirring at a high speed for 10-20 minutes; (2) adding a wetting dispersant and a part of solvent into a reactor, and stirring at a medium speed for 5-10 minutes; (3) adding the amino resin, the pigment and the residual solvent into a reactor, and stirring at a high speed for about 10 minutes; (4) the remaining water was added to the reactor.
TABLE 3 comparative coating compositions CE5-8
| CE5(wt％) | CE6(wt％) | CE7(wt％) | CE8(wt％) | |
| Film-forming resina | 10.8 | 10.8 | 3 | 10.8 |
| Amino resinb | 2.0 | 2.0 | 1.4 | 2.0 |
| Pigment (I)c | 1.2 | 1.2 | 1.2 | 4 |
| Wetting and dispersing agentd | 0.3 | 0.3 | 0.3 | 0.3 |
| Solvent(s) | 16e1 | 16e2 | 16e3 | 16e3 |
| Water (W) | 69.7 | 69.7 | 78.1 | 66.9 |
aA polycarbonate-based polyurethane resin having a tensile elongation of at least about 180% and a tensile strength of at least about 5100psi, dispersed in dipropylene glycol dimethyl ether at a solids content of about 30-40 wt%;
bpartially and/or fully methylated amino resins, about 80-92% solids content, as from Enlish (INEOS);
cthe aluminum powder slurry coated by the fumed silica has a solid content of about 43-47 wt% and comes from Eika (Eckart);
dfrom BYK;
e1a combination of isopropyl alcohol, butyl glycol ether, hexyl glycol ether, and dipropylene glycol methyl ether in a weight ratio of about 3.1:9.4:1.4: 4;
e2isopropyl alcohol, butyl glycol ether anda combination of ethylene glycol hexyl ether;
e3a combination of isopropyl alcohol, butyl cellosolve, hexyl cellosolve and dipropylene glycol methyl ether in a weight ratio of about 1.5-3.5: 8-11: 2-3.5: 1-2.5.
Performance testing
The following performance tests were performed on the waterborne coating composition Ex1-3 provided by the present invention and the comparative coating composition CE 1-8:
(1) the matching property: in the present invention, the compatibility of the coating composition according to the invention was evaluated by measuring the adhesion between the coating and the powder and liquid basecoat/clearcoats, respectively, wherein the adhesion was measured according to the GB/T9286 standard.
The sample surface was scribed with a NT knife at 6X6 lines (25 lines of 1 mm)2Squares, score lines and base), keeping the test surface as flat as possible (keeping the edge sharp). If the sample is too small and does not have enough space for grid division, the sample is divided into 45-degree cross grids. Nichiban tape (No.405), Scotch tape (No.610) or other tapes of the same type (18mm wide, tape tack should be 5.3N/18mm wide or more) were adhered to the sample surface, and the tape was compacted with an eraser to make the tape sufficiently contact with the test surface and left to stand for 3 minutes. The tape was quickly torn off in the 90 degree direction and the test surface was visually inspected and rated according to ISO standards.
ISO standard rating:
level 0: 5B
The edges of the cuts were completely smooth without any peeling of the grid edges.
Level 1: 4B
And small pieces are stripped at the intersection of the cuts, and the actual damage in the grid cutting area is less than or equal to 5 percent.
Stage 2: the edge or the intersection of the 3B cut is stripped, and the area of the 3B cut is 5% -15%.
And 3, stage: 2B, partial peeling or whole-piece peeling is carried out along the edge of the cut, or partial lattices are peeled by whole pieces, and the peeling area is 15-35 percent.
4, level: the 1B cut edge is larger than the peel or some squares are partially or totally peeled off, and the area of the 1B cut edge is 35-65%.
And 5, stage: 0B, a piece of paint falls off at the scribing edge and the intersection, and the total falling-off finish paint is more than 65 percent.
TABLE 4 adhesion of coating composition Ex1-3 according to the invention
| Ex1 | Ex2 | Ex3 | |
| Powder primer + Ex1-3+ powder varnish | Level 0 | Level 0 | Level 0 |
| Liquid varnish + Ex1-3+ liquid varnish | Level 0 | Level 0 | Grade 0 |
Note: the powder primer is PCFC90203L black primer, the curing condition is 20 minutes at 177 ℃, and the film thickness is 80-100 micrometers; the powder varnish is PCC10103 transparent powder paint from PPG or 158C121 transparent powder paint from Akoz, the curing condition is 20 minutes at 180 ℃, and the film thickness is 80-120 micrometers; the liquid primer is WHMC900001, and the curing condition is 20 minutes at 140 ℃ to 50 minutes at 170 ℃, and can be coated and cured with the coating composition in a wet-on-wet manner; the liquid varnish is DCC62009 liquid varnish, and the curing condition is that the liquid varnish can be coated and cured with the coating composition of the invention in a wet-on-wet manner at the temperature of 150 ℃ for 30 minutes to 170 ℃ for 50 minutes; the curing condition of the waterborne coating composition Ex1-3 provided by the invention is 20 minutes at 150 ℃.
TABLE 5 adhesion of comparative coating composition CE1-3
| CE1 | CE2 | CE3 | |
| Powder primer + CE1-3+ powder varnish | Stage 2 | Stage 2 | Stage 2 |
| Liquid varnish + CE1-3+ liquid varnish | Stage 2 | Stage 2 | Stage 2 |
Note: the powder primer is PCFC90203L black primer, the curing condition is 20 minutes at 177 ℃, and the film thickness is 80-100 micrometers; the powder varnish is PCC10103 transparent powder paint from PPG or 158C121 transparent powder paint from Akoz, the curing condition is 20 minutes at 180 ℃, and the film thickness is 80-120 micrometers; the liquid primer is WHMC900001, and the curing condition is 20 minutes at 140 ℃ to 50 minutes at 170 ℃, and can be coated and cured with the coating composition in a wet-on-wet manner; the liquid varnish is DCC62009 liquid varnish, and the curing condition is that the liquid varnish can be coated and cured with the coating composition of the invention in a wet-on-wet manner at the temperature of 150 ℃ for 30 minutes to 170 ℃ for 50 minutes; the curing conditions for comparative coating composition CE1-3 were 20 minutes at 150 ℃.
Moreover, when the curing conditions were changed to 170 ℃ for 50 minutes, the coating composition Ex1-3 according to the invention had the same excellent compatibility, i.e. adhesion to powder base/varnish or liquid base/varnish was of grade 0; however, the compatibility of the comparative coating composition CE1-3 with powder and liquid paints became markedly worse, with adhesion of grade 4 to either the powder base/clear or the liquid base/clear.
(2) Yellowing at high temperature: whether yellowing at high temperature occurs is evaluated by determining the single-angle color difference exhibited by the coating before and after being subjected to high temperature. The color of the coating was determined based on the laa b color system specified in JIS Z8729. When the single-angle color difference delta b of the coating is less than 0.5, the coating is considered not to be yellowed at high temperature; on the contrary, yellowing at high temperature is considered to occur.
First, the aqueous coating composition Ex1-3 and the comparative coating composition CE1-3 provided by the present invention were applied to a primed aluminum substrate and then cured under the following conditions, respectively: baking at 120 deg.C for 20 min, baking at 140 deg.C for 20 min, and baking at 190 deg.C for 50 min.
Herein, the b value of the coated substrate was measured using a commercially available single-angle color difference meter. The b value of the coating formed by baking at 120 ℃ for 20 minutes was measured as the initial value b0. The b value of the coating formed under the curing conditions of baking at 140 ℃ for 20 minutes and baking at 190 ℃ for 50 minutes was measured. The Δ b value is two (i.e., b)0And b) absolute value of the difference.
The experimental result shows that the coating formed by the water-based paint composition Ex1-3 has delta b values less than 0.5 at the temperature of 140 ℃ and 190 ℃ and does not yellow at high temperature. In contrast, comparative coating composition CE1-3 gave a coating having a Δ b value greater than 0.5 after 50 minutes baking at 190 ℃ and yellowing at elevated temperatures.
(3) Aluminum powder orientation: the waterborne coating composition Ex1-3 according to the invention and the comparative coating CE1-3 were applied to primed aluminum substrates with the following construction parameters and then cured by baking at 150 ℃ for 20 minutes. The surface gloss and specular effect of the cured coating were observed.
The gravity spray gun with the caliber of 1.0 has the gun distance of 25cm and 20 spraying passes.
The coating formed by the water-based paint composition Ex1-3 provided by the invention has excellent glossiness and mirror surface effect. In contrast, the coating formed by comparative coating composition CE1-3 exhibited blooming and loss of gloss effects.
(4) Water resistance: the water resistance of the coating is evaluated by determining the adhesion of the coating after soaking in water for a certain time, for example, 2 days at 63 ℃ or 10 days at 38 ℃. The method of determining the adhesion and the rating criteria are as described above.
The test results were as follows:
note: the powder primer is PCFC90203L black primer, the curing condition is 20 minutes at 177 ℃, and the film thickness is 80-100 micrometers; the powder varnish is PCC10103 transparent powder paint from PPG or 158C121 transparent powder paint from Akoz, the curing condition is 20 minutes at 180 ℃, and the film thickness is 80-120 micrometers; the liquid primer is WHMC900001, and the curing condition is 20 minutes at 140 ℃ to 50 minutes at 170 ℃, and the liquid primer can be coated and cured with the coating composition in a wet-on-wet manner; the liquid varnish is DCC62009 liquid varnish, and the curing condition is that the liquid varnish can be coated and cured with the coating composition of the invention in a wet-on-wet manner at the temperature of 150 ℃ for 30 minutes to 170 ℃ for 50 minutes; the curing conditions of the waterborne coating composition Ex1-3 and the comparative coating composition CE1-8 provided by the invention are 20 minutes at 120 ℃, 20 minutes at 140 ℃ and 50 minutes at 170 ℃ respectively.
(5) Recoating performance: the recoatability of the coating was evaluated by determining the adhesion of the coating after repeated applications. The method of determining the adhesion and the rating criteria are as described above.
The test results were as follows:
note: the powder primer is PCFC90203L black primer, the curing condition is 20 minutes at 177 ℃, and the film thickness is 80-100 micrometers; the powder varnish is PCC10103 transparent powder paint from PPG or 158C121 transparent powder paint from Akoz, the curing condition is 20 minutes at 180 ℃, and the film thickness is 80-120 micrometers; the liquid primer is WHMC900001, and the curing condition is 20 minutes at 140 ℃ to 50 minutes at 170 ℃, and can be coated and cured with the coating composition in a wet-on-wet manner; the liquid varnish is DCC62009 liquid varnish, and the curing condition is that the liquid varnish can be coated and cured with the coating composition of the invention in a wet-on-wet manner at the temperature of 150 ℃ for 30 minutes to 170 ℃ for 50 minutes; the curing conditions of the waterborne coating composition Ex1-3 and the comparative coating composition CE1-8 provided by the invention are 20 minutes at 120 ℃, 20 minutes at 140 ℃ and 50 minutes at 170 ℃ respectively.
(6) Moisture resistance: the moisture resistance of the coating was evaluated by determining the adhesion of the coating after a certain period of time in a humid environment, i.e. after 10 days at 38 ℃. The method of determining the adhesion and the rating criteria are as described above.
Experiments show that: when the waterborne coating composition Ex1-3 is used with powder base/varnish and liquid base/varnish, the adhesion force of the coating in a humid environment is 0 grade, and the coating has excellent moisture resistance.
(7) Stability: after the coating composition was allowed to stand at 50 ℃ for 30 days, it was observed whether the coating gelled, i.e., the viscosity increased. The viscosity value was determined by a commercially available viscosity tester and if the viscosity value increased more than 10% of the initial viscosity, the stability was considered poor.
The aqueous coating composition Ex1-3 according to the invention had excellent stability, whereas the coating composition of the comparative coating composition CE5-6 had poor stability and gelled.
In addition, the coating formed by the water-based coating composition has excellent gas generating performance. After standing at 40 ℃ for 40 days, the gas evolution was 0. Also, the aqueous coating composition according to the present invention has a wide operating window. Specifically, when the coating layer formed by the aqueous coating composition of the present invention is baked at 120 to 170 ℃ for 20 to 50 minutes, for example, 120 ℃ for 20 minutes, 140 ℃ for 20 minutes, and 170 ℃ for 50 minutes, the coating layer has excellent compatibility, high-temperature yellowing resistance, aluminum powder orientation, water resistance, recoatability, moisture resistance, and stability, as shown in the test results of (4) and (5) above.
The performance test results show that the water-based paint composition provided by the invention not only meets the requirements of safety and environmental protection laws and regulations on VOC, but also has the advantages of good matching property, excellent appearance, high adhesive force, good water resistance, recoatability, moisture resistance, good stability and the like, and can meet the application of paint for automobile hubs.
While particular aspects of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Claims (16)
1. The water-based paint composition comprises a film-forming resin, an amino resin, a pigment and an organic solvent, wherein the film-forming resin comprises a polycarbonate-based polyurethane resin, the pigment comprises fumed silica-coated aluminum powder, the weight ratio of the pigment to the sum of the film-forming resin and the amino resin is 0.04-0.2: 1, the organic solvent comprises isopropanol, ethylene glycol butyl ether, ethylene glycol hexyl ether and dipropylene glycol methyl ether, and the weight ratio of the isopropanol, the ethylene glycol butyl ether, the ethylene glycol hexyl ether and the dipropylene glycol methyl ether in the organic solvent is 1.5-3.5: 8-11: 2-3.5: 1-2.5.
2. The aqueous coating composition of claim 1, wherein the polycarbonate-based polyurethane resin has a stretch ratio of at least 180%.
3. The aqueous coating composition of claim 1, wherein the polycarbonate-based polyurethane resin has a tensile strength of at least 5100 psi.
4. The aqueous coating composition of claim 1, wherein the amino resin comprises a methylated amino resin.
5. An aqueous coating composition as claimed in claim 4, wherein the methylated amino resin contains up to 10 mol% of methylol groups.
6. An aqueous coating composition as claimed in any one of claims 1 to 5, wherein the weight ratio of the polycarbonate-based polyurethane resin and the amino resin is 2 to 4:1.
7. The aqueous coating composition of claim 1, wherein the coating composition has a VOC value of at most 420g/L measured free of water.
8. An aqueous coating composition according to claim 1, wherein the coating adhesion between the coating composition and a powder primer or powder clearcoat is of the 0-grade, measured according to the method of GB/T9286.
9. An aqueous coating composition according to claim 1, wherein the coating adhesion between the coating composition and a liquid primer or liquid clear coat is of the 0-grade, measured according to the method of GB/T9286.
10. The aqueous coating composition according to claim 1, wherein a coating layer formed by the coating composition has a single-angle color difference Δ b of less than 0.5 after being left at 190 ℃ for 50 minutes according to JIS Z8729.
11. Use of an aqueous coating composition according to any one of claims 1 to 10 for coating a substrate.
12. The use of claim 11, wherein the substrate comprises a metal.
13. The use of claim 11, wherein the substrate comprises an automobile hub.
14. A coated substrate comprising at least one coating layer formed from the aqueous coating composition of any one of claims 1-10.
15. The coated substrate of claim 14, wherein the substrate comprises a metal.
16. The coated substrate of claim 14, wherein the substrate comprises an automobile hub.
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| US20130011590A1 (en) * | 2011-07-06 | 2013-01-10 | Bayer Materialscience Ag | Waterborne polyurethane coating compositions |
| CN104371449A (en) * | 2014-09-16 | 2015-02-25 | 江程 | Aluminum powder metal anti-corrosion coating material and preparation method thereof |
| CN107459900A (en) * | 2017-09-15 | 2017-12-12 | 万华化学（宁波）有限公司 | Water-based aluminium alloy wheel hub coating composition and its preparation method and application |
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