CN116970311A

CN116970311A - Two-part coating composition and articles formed therefrom

Info

Publication number: CN116970311A
Application number: CN202210597635.9A
Authority: CN
Inventors: 尧华; 杨轶辉
Original assignee: Xuanwei Nantong Coatings Co ltd
Current assignee: Xuanwei Nantong Coatings Co ltd
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2023-10-31

Abstract

The present application relates to a two-part coating composition and articles formed therefrom. The two-part coating composition comprises: a) A film-forming resin composition comprising a fluorocarbon resin, a hydroxy-functional acrylic resin, an anti-settling agent, and optionally additional additives; and b) a curing agent comprising a polyisocyanate, wherein the molar ratio of-NCO of the polyisocyanate to-OH of the resin component in the film-forming resin composition is in the range of 1.6-2.2:1; and wherein the solids content of the curing agent is in the range of 80-100%. The two-component coating composition of the application can be used as a top coat to provide good protective performance for a substrate.

Description

Two-part coating composition and articles formed therefrom

Technical Field

The present application relates to a two-component coating composition, and more particularly to a two-component coating composition having a high solids content containing fluorocarbon resin and articles made therefrom.

Background

As one of important chemical products, fluoroolefin polymers or copolymers of fluoroolefins with other monomers are called fluorocarbon resins. Fluorocarbon resins have wide application in various fields, particularly in the field of coatings. The coating material prepared by taking fluorocarbon resin as a main film forming material is called as a fluorocarbon coating material. Currently, fluorocarbon coatings commonly available on the market have excellent weather resistance, but are expensive and not affordable to customers. In addition, the solid content of the common fluorocarbon coating is low, and a large amount of Volatile Organic Compounds (VOC) are required to be discharged in the application process, so that the environmental protection requirement cannot be met.

In order to prepare a fluorocarbon coating having a high solids content, the solids content of the fluorocarbon resin may be optionally increased. In general, the solid content of fluorocarbon resin is closely related to the cost, and the use of fluorocarbon resin with higher solid content inevitably increases the price of fluorocarbon coating obviously, which is unfavorable for popularization and application of fluorocarbon coating. In addition to increasing the solids content of the fluorocarbon resin, it is generally optional to add relatively large amounts of pigment/filler to the fluorocarbon coating. However, the addition of a relatively large amount of pigment/filler tends to cause poor storability such as sedimentation and delamination of the fluorocarbon coating.

Accordingly, there is a need in the coating industry for improved coating compositions having high solids fluorocarbon resins.

Disclosure of Invention

In one aspect, the present invention provides a two-part coating composition comprising: a) A film-forming resin composition comprising a fluorocarbon resin, a hydroxy-functional acrylic resin, a pigment/filler, and optionally additional additives; and b) a curing agent comprising a polyisocyanate, wherein the molar ratio of isocyanate functional groups (-NCO) of the polyisocyanate to hydroxyl functional groups (-OH) of the resin component of the film-forming resin composition is in the range of 1.6-2.2:1; and wherein the solids content of the curing agent is in the range of 80-100%. In one embodiment of the present invention, the anti-settling agent included in the film-forming resin composition is selected from silica, polyethylene wax, polyamide wax, or a combination thereof. In another embodiment of the present invention, the film-forming resin composition further comprises a diluent, preferably the diluent is a reactive diluent or is a petroleum resin having a weight average molecular weight of not more than 2000g/mol as a non-reactive diluent.

In another aspect, the application relates to an article of manufacture comprising: a substrate; a primer layer coated on at least a portion of a surface of the substrate; a topcoat applied over the basecoat, wherein the topcoat is formed from the two-component coating composition of the present application. Preferably, the substrate comprises a metal substrate, a wood substrate, a plastic substrate, a glass substrate, a ceramic substrate, or a combination thereof.

The inventors of the present application have surprisingly found that in the formulation of fluorocarbon coatings, by compounding in a conventional fluorocarbon resin an amount of an isocyanate-reactive hydroxy-functional acrylic resin and by further increasing the amount of curing agent polyisocyanate having a higher solids content such that the molar ratio of-NCO of the polyisocyanate to-OH of the resin component in the film-forming resin composition is in the range of 1.6 to 2.2:1, a fluorocarbon coating having a significantly increased solids content can be obtained, and that coatings formed from fluorocarbon coatings so formulated have significantly better abrasion resistance and chemical resistance, which was difficult to foresee before the present application.

The inventors of the present application have also surprisingly found that in the formulation of fluorocarbon coatings, by adding specific anti-settling agents and diluents, fluorocarbon coating compositions having a suitably reduced viscosity and desirable high temperature storage properties can be obtained while ensuring a high solids content of the fluorocarbon coating composition, which was difficult to expect before the present application.

The details of one or more embodiments of the application are set forth in the description below. Other features, objects, and advantages of the application will be apparent from the description and claims.

Definition of the definition

As used herein, "a," "an," "the," "at least one," and "one or more" or the use of no quantitative terms are used interchangeably. Thus, for example, a component comprising "an" additive may be interpreted as referring to the component comprising "one or more" additives.

Where a composition is described as comprising or including a particular component, it is contemplated that optional components not referred to by the present application are not excluded from the composition, and that the composition may consist or consist of the recited components, or where a method is described as comprising or including a particular process step, it is contemplated that optional process steps not referred to by the present application are not excluded from the method, and that the method may consist or consist of the recited process steps.

For simplicity, only a few numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form a range not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and any upper limit may be combined with any other upper limit to form a range not explicitly recited. Furthermore, each point or individual value between the endpoints of the range is included within the range, although not explicitly recited. Thus, each point or individual value may be combined as a lower or upper limit on itself with any other point or individual value or with other lower or upper limit to form a range that is not explicitly recited.

In this context, "coating" and "paint film" have the same meaning, both being formed after application and curing of the two-component coating composition.

In the context of the present application, the term "two-part coating composition" refers to a coating composition consisting of two or more separately stored components that are mixed together at the time of use and that can be dried and cured within an acceptable period of time to form a coating having the desired mechanical properties (e.g., hardness).

As used herein, the phrase "the molar ratio of isocyanate functional groups (-NCO) of the polyisocyanate to hydroxyl functional groups (-OH) of the resin component in the film-forming resin composition" refers to the ratio of the molar equivalent of NCO in the polyisocyanate as the curing agent to the sum of the molar equivalent of OH of the fluorocarbon resin and the hydroxyl-functional acrylic resin as the resin component in the film-forming resin composition, wherein the content of isocyanate functional groups of the polyisocyanate as the curing agent is provided by the supplier and the content of hydroxyl functional groups of the fluorocarbon resin and the hydroxyl-functional acrylic resin as the resin component is determined by calculation of the hydroxyl value of the resin.

In the context herein referring to the components and mixtures of components, the term "solids content" is also referred to as mass solids content, referring to the mass percent determined by: and baking the components or the mixture to be tested for 1 hour at the temperature of 110 ℃ under normal pressure, and then calculating the ratio of the mass of the residual materials after baking to the original mass of the components or the mixture to be tested, so as to obtain the mass solid content of the components or the mixture to be tested.

As used herein, the term "diluent" refers to any component used to adjust the viscosity of a system, which may include reactive diluents and non-reactive diluents. Herein, the term "reactive diluent" refers to a diluent that can react with isocyanate; accordingly, the term "non-reactive diluent" refers to a diluent that does not react with any of the components in the system.

As used herein, the term "basecoat" refers to a coating composition that can be applied to a substrate and dried, crosslinked, or otherwise hardened to form a non-tacky continuous film having sufficient adhesion to the substrate surface.

As used herein, the term "topcoat" refers to a coating composition that can be applied over a basecoat or a color-modifying layer and dried, crosslinked, or otherwise hardened to form a decorative or protective outermost coating layer. Further, such topcoats are capable of withstanding prolonged outdoor exposure without exhibiting visible undesirable degradation.

The terms "comprising" and "including" and variations thereof, when appearing in the specification and claims, are not intended to be limiting.

In the present invention, a numerical range defined by endpoints includes all numbers within that range such as the range of 1 to 5 includes the values 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. Moreover, the disclosed numerical ranges include all sub-ranges within the broader range, e.g., a range of 1 to 5 includes sub-ranges 1 to 4, 1.5 to 4.5, 1 to 2, etc.

The terms "preferred" and "preferably" refer to embodiments of the invention that may provide certain benefits in certain circumstances. However, other embodiments may be preferred under the same or other circumstances. In addition, recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

Detailed Description

Embodiments of the present invention provide a two-part coating composition comprising: a) A film-forming resin composition comprising a fluorocarbon resin, a hydroxy-functional acrylic resin, a pigment/filler, an anti-settling agent, and optionally additional additives; and b) a curing agent comprising a polyisocyanate, wherein the molar ratio of isocyanate functional groups (-NCO) of the polyisocyanate to hydroxyl functional groups (-OH) of the resin component of the film-forming resin composition is in the range of 1.6-2.2:1; and wherein the solids content of the curing agent is in the range of 80-100%.

In general, in a two-component coating composition using isocyanate as a curing agent, considering the case where NCO is lost due to moisture in the environment in practical construction, the molar amount of isocyanate functional groups NCO in the curing agent relative to hydroxyl functional groups OH in the resin component is excessive, typically isocyanate functional groups NCO is excessive by 20% relative to hydroxyl functional groups but not more than 50% at the most, because this may cause a decrease in coating properties. However, the inventors of the present application have surprisingly found that in the formulation of fluorocarbon coatings, the molar ratio of isocyanate functional groups (-NCO) of the polyisocyanate curing agent to hydroxyl functional groups (-OH) of the resin component in the film-forming resin composition is controlled to be in the range of 1.6 to 2.2:1, with a relatively high solids content, such as a solids content of 75% by weight or more, even a solids content of 75% by weight to 90% by weight, and that coatings formed therefrom have excellent abrasion resistance and chemical resistance, which were difficult to foresee prior to the present application. In one embodiment according to the application, the solids content of the curing agent is in the range of 90-100%. In another embodiment according to the present application, the molar ratio of isocyanate functional groups (-NCO) of the polyisocyanate as the curing agent to hydroxyl functional groups (-OH) of the resin component in the film-forming resin composition is controlled within the range of 1.8-2.1:1. In a preferred embodiment according to the present application, the solid content of the curing agent is in the range of 90-100% and the molar ratio of isocyanate functional groups (-NCO) of the polyisocyanate as curing agent to hydroxyl functional groups (-OH) of the resin component in the film-forming resin composition is controlled in the range of 1.8-2.1:1, the fluorocarbon coating composition thus formed having an even higher solid content, which may even be as high as 92% by weight. Thus, in one embodiment of the present application, the two-part coating composition is particularly suitable as a topcoat to provide protection, particularly weather protection, to a substrate.

Film-forming resin composition

In the two-component coating composition according to the application, the film-forming resin composition constitutes the main part thereof, which comprises a fluorocarbon resin, a hydroxy-functional acrylic resin, a pigment/filler and additional additives. In the context of the present application, the term "film-forming resin composition" refers to a composition comprising a resin which can be applied to a substrate or paint film and in which the contained resin is dried, crosslinked or otherwise hardened as desired with a suitable curing agent to form a non-tacky continuous film on the substrate or paint film.

In an embodiment according to the present application, the film-forming resin composition comprises a fluorocarbon resin, and thus the coating composition formed therefrom is also referred to as a fluorocarbon coating. In one embodiment of the present application, the fluorocarbon resin, which is one of the resin components of the film-forming resin composition, is hydroxy-functionalized and thus can undergo a crosslinking reaction with the polyisocyanate as the curing agent. In some embodiments of the application, the fluorocarbon resin has a hydroxyl number in the range of 45-65mg KOH/g, preferably in the range of 50-60mg KOH/g. In one embodiment of the present application, the fluorocarbon resin selected is conventional and has a solids content in the range of 50 to 60 percent, so the cost of the fluorocarbon coating composition is acceptable.

In one embodiment according to the application, the fluorocarbon resin has a suitable molecular weight in order to provide sufficient mechanical strength to the resulting coating system. Preferably, the fluorocarbon resin has a weight average molecular weight greater than 50,000g/mol, preferably in the range of 50,000g/mol to 120,000 g/mol. If the molecular weight of the polymer is too high, the coating composition formulated therefrom is difficult to coat uniformly and unsuitable for construction operations; if the molecular weight of the polymer is too low, the coating compositions formulated therefrom will have limited strength of the paint film formed upon curing. Thus, in some embodiments according to the present application, the molecular weight of the fluorocarbon resin is appropriate within the above-described range. As an exemplary illustration, one or more of polytetrafluoroethylene fluorocarbon resin, polyvinylidene fluoride fluorocarbon resin, polyvinyl fluoride fluorocarbon resin, chlorotrifluoroethylene-vinyl ether fluorocarbon resin, tetrafluoroethylene-vinyl ether fluorocarbon resin, or any other fluorocarbon resin known in the paint art may be used as the fluorocarbon resin. In an embodiment according to the present application, any commercially available fluorocarbon resin may be used, for example JF-2X, DF-300, JF-3X, ZHM-5, etc. commercially available from Sanaful, chemical industry, LF400, LF600X, etc. commercially available from Asahi sonia, etc. may be used.

In one embodiment according to the present application, the amount of fluorocarbon resin used may vary within wide limits. For example, the fluorocarbon resin may be not more than 50 weight percent, not more than 45 weight percent, not more than 40 weight percent, and at least 25 weight percent, at least 28 weight percent, at least 30 weight percent, relative to the total weight of the film-forming resin composition. In a preferred embodiment according to the application, the amount of fluorocarbon resin ranges from 30 to 40 percent by weight relative to the total weight of the film-forming resin composition. In general, the desired fluorocarbon resin amount can be selected empirically, generally based on the desired weatherability of the paint film.

As described above, fluorocarbon resins have excellent weather resistance due to the presence of fluorine, and thus applications of fluorocarbon resins in the field of coating materials are attracting increasing attention. However, the solids content of conventional fluorocarbon resins is generally not high, but is only 50 to 60% by weight. In order to increase the solid content of the fluorocarbon coating, the solid content of the fluorocarbon resin may be optionally increased. In general, the solid content of fluorocarbon resin is closely related to the cost, and the use of fluorocarbon resin with higher solid content inevitably increases the price of fluorocarbon coating obviously, which is unfavorable for popularization and application of fluorocarbon coating. In embodiments according to the present application, the cost of fluorocarbon coating compositions can be significantly reduced by blending an amount of isocyanate-reactive hydroxyl-functionalized acrylic resin in a conventional fluorocarbon resin. Both the hydroxy-functional acrylic resin and the fluorocarbon resin do not react and do not adversely affect the storage stability of the coating. And through the co-curing and crosslinking reaction with the polyisocyanate curing agent, the hydroxyl-functionalized acrylic resin and the fluorocarbon resin can jointly form a three-dimensional crosslinked network, and in the three-dimensional crosslinked network, the hydroxyl-functionalized acrylic resin and the fluorocarbon resin are alternately distributed, so that the fluorocarbon resin can enhance the weather resistance of the whole coating.

In one embodiment according to the present application, the hydroxyl value of the hydroxyl functional acrylic resin is not higher than 130mg KOH/g, preferably in the range of 70-120mg KOH/g, more preferably in the range of 60-90mg KOH/g, still more preferably in the range of 70-80mg KOH/g, so that the desired curing effect can be achieved. The hydroxyl number is measured by ISO 4629 titration. If the polymer hydroxyl number is too high, the film-forming resin composition formulated therefrom gels too quickly after mixing with the curing agent, and is not suitable for construction operations; if the hydroxyl value of the polymer is too low, the curing reaction of the film-forming resin composition formulated therefrom with the curing agent is too slow, resulting in a decrease in the construction efficiency. Thus, in some embodiments according to the present application, hydroxyl numbers of the hydroxyl-functional acrylic resins are within the ranges described above, which allows for proper pot life of the film-forming resin compositions formulated therefrom upon mixing with the curing agent.

In one embodiment according to the application, the hydroxy-functional acrylic resin has a suitable molecular weight in order to provide sufficient mechanical strength to the resulting coating system. Preferably, the at least one hydroxy-functional acrylic resin has a weight average molecular weight greater than 50,000g/mol, preferably in the range of 50,000g/mol to 120,000 g/mol. If the molecular weight of the polymer is too high, the coating composition formulated therefrom is difficult to coat uniformly and unsuitable for construction operations; if the molecular weight of the polymer is too low, the coating compositions formulated therefrom will have limited strength of the paint film formed upon curing. Thus, in some embodiments according to the present application, the molecular weight of the hydroxy-functionalized acrylic resin is appropriate within the above-described ranges.

The hydroxy-functional acrylic resins disclosed above may be made, for example, using techniques well known to those of ordinary skill in the art. For example, the hydroxy-functional acrylic resin may be a hydroxy-containing copolymer of an ethylenically unsaturated compound. These copolymers are copolymers of hydroxyl-containing olefin monomers with hydroxyl-free olefin monomers. Examples of suitable monomers include vinyl and vinylidene monomers such as styrene, alpha-methylstyrene, o-and p-chlorostyrene, o-, m-and p-methylstyrene, p-tert-butylstyrene, acrylic acid, (meth) acrylonitrile, acrylic acid and methacrylates having from 1 to 8 carbon atoms (e.g., ethyl acrylate, methyl acrylate, n-or isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and isooctyl methacrylate), diesters of fumaric acid, itaconic acid or maleic acid having from 4 to 8 carbon atoms in the alcohol component, (meth) acrylamides, vinyl esters of alkane monocarboxylic acids having from 2 to 5 carbon atoms (e.g., vinyl acetate or vinyl propionate) and hydroxyalkyl esters of acrylic or methacrylic acid having from 2 to 4 carbon atoms in the hydroxyalkyl residue (e.g., 2-hydroxyethyl acrylate or methacrylate, 2-hydroxypropyl acrylate or methacrylate, 4-hydroxybutyl acrylate or trimethacrylate, mono-or trimethacrylate) can also be used to prepare the hydroxy-functional acrylate or mono-methacrylate resins.

In some embodiments according to the present application, the use of a relatively high solids hydroxyl-functional acrylic resin is preferred because it can simultaneously increase the solids content of the fluorocarbon coating. In one embodiment according to the application, the hydroxyl-functional acrylic resin has a solids content in the range of 70-80%.

As examples of hydroxy-functionalized acrylic resins, any conventional hydroxy-functionalized acrylic resins may be used, such as ACRYDIC A-859, A-858, ZHP-2152, commercially available from DIC, and AC1170, AC1171, ACR6700, etc. commercially available from Tongde chemical industry may also be used.

In an embodiment according to the application, the hydroxy-functional acrylic resin is used in addition to the fluorocarbon resin in an amount lower than the amount of fluorocarbon resin. In one embodiment according to the application, the hydroxyl-functional acrylic resin is used in an amount ranging from 5 to 20% by weight, preferably from 10 to 15% by weight, relative to the total weight of the film-forming resin composition. In general, the desired amount of hydroxy-functional resin can be selected empirically, usually based on the film forming properties of the paint film.

In an embodiment according to the present application, the film-forming resin composition contains a substantial amount of pigment/filler in addition to the above-described resin components so as to be able to raise the solid content of the fluorocarbon coating. In the context of the present application, the filler may be organic or inorganic, for example in particulate form. The shape of the particles is not particularly limited and may have any suitable shape. The average particle size of the filler may vary over a wide range, for example, from about 10 nanometers to about 50 microns, but in order to increase the clarity of the resulting coating, the filler should not have an excessively large average particle size, for example, D ₅₀ . Preferably, the filler has a D of no more than about 10 microns ₅₀ . Some fillers, in addition to functioning as volume extenders for the coating, impart one or more desired properties to the composition and/or to the coating formed from the composition. For example, some fillers may impart a desired color to the composition and the coating resulting from the composition. In this case, such fillers are also referred to as "pigments". Some fillers may improve chemical and/or physical properties, in particular the physical properties of the polymerThe composition gives coatings with mechanical properties. In this case, such filler is also referred to as "reinforcing filler". As examples of pigments/fillers, silicate, wollastonite, kaolin, titanium oxide, calcium carbonate, talc, barium sulfate, and any combination thereof may be used. In one embodiment according to the invention, wollastonite, titanium dioxide, or a combination thereof may be used.

In one embodiment of the invention, the amount of pigment/filler is not less than 30 wt%, preferably not less than 32 wt%, more preferably not less than 35 wt%, relative to the total weight of the film-forming resin composition, so as to be able to significantly increase the solids content of the fluorocarbon coating composition. However, in view of the adhesion and storage stability of the film-forming resin composition, the amount of pigment/filler is not more than 55% by weight, preferably not more than 50% by weight, more preferably not more than 45% by weight, relative to the total weight of the film-forming resin composition. In a preferred embodiment according to the invention, the pigment filler is used in an amount ranging from 35 to 45% by weight, preferably from 38 to 45% by weight, relative to the total weight of the film-forming resin composition.

As described above, the addition of a large amount of pigment and filler in the formulation of the fluorocarbon coating composition can significantly increase the solid content of the coating composition, but this causes precipitation of the coating composition, occurrence of defects such as delamination, and the like, and the storage stability of the coating is lowered. The inventors of the present application have surprisingly found that by adding specific anti-settling agents and diluents to film-forming resin compositions, fluorocarbon coating compositions having a suitably reduced viscosity and desirable high temperature storage properties can be obtained while ensuring a high solids content of the fluorocarbon coating composition, which was difficult to expect before the present application.

In one embodiment according to the present application, in order to improve the storage stability of the coating material, an anti-settling agent selected from polyethylene wax, polyamide wax, silica aerogel, or a combination thereof may be used, and preferably, polyamide wax or silica aerogel may be used as the anti-settling agent. The inventors of the present application found that the kind of the anti-settling agent is important for obtaining a desired anti-settling effect; anti-settling agents such as polyamide wax, silica aerogel, unlike other conventional anti-settling agents such as bentonite, can ensure high temperature storage properties of the coating composition while ensuring anti-settling effect of the coating composition by adding these specific anti-settling agents, which was difficult to foresee before the present application.

In one embodiment according to the invention, the anti-settling agent is used in an amount ranging from 0.5 to 3% by weight, preferably from 0.5 to 2% by weight, relative to the total weight of the film-forming resin composition. In general, the desired anti-settling agent may be selected empirically, typically based on the storage requirements of the coating composition.

In some embodiments according to the present invention, in order to reduce the viscosity of the coating composition, a certain amount of diluent may be added. As noted above, diluent refers to any component used to adjust the viscosity of a system, which may include reactive diluents and non-reactive diluents. The addition of the above-mentioned diluent can appropriately reduce the viscosity of the coating composition on the basis of ensuring the solid content of the fluorocarbon coating composition to improve the applicability thereof at the stage of the work. In a preferred embodiment of the invention, the solids content of the diluent is greater than 98%.

In some embodiments of the present invention, in the formulation of the coating composition, a reactive diluent, i.e., a diluent that can react with isocyanate, is added to the film-forming resin composition in an amount. In view of the need to increase the solids content of the coating compositions, the reactive diluents described above include compounds having a solids content of greater than 98% or greater. As an exemplary illustration, reactive diluents include cardanol-type reactive diluents having hydroxyl functionality, such as 5300 commercially available from vantage of zhejiang. In one embodiment according to the invention, the reactive diluent is used in an amount ranging from 2 to 10% by weight, preferably ranging from 2 to 8% by weight, relative to the total weight of the film-forming resin composition. In general, the amount of reactive diluent desired can be selected empirically, typically based on the viscosity requirements of the coating composition.

In some embodiments of the present invention, in the formulation of the coating composition, an amount of an inactive diluent, i.e., a diluent that does not react with any of the components in the system, is added to the film-forming resin composition. In view of the need to increase the solids content of the coating composition, such non-reactive diluents include petroleum resins having a low molecular weight. As an exemplary illustration, the non-reactive diluent is a petroleum resin having a weight average molecular weight of no more than 2000 g/mol. In one embodiment according to the invention, the amount of non-reactive diluent is in the range of 2 to 10 wt%, preferably in the range of 2 to 8 wt%, relative to the total weight of the film-forming resin composition. In general, the amount of non-reactive diluent desired can be selected empirically, typically based on the viscosity requirements of the coating composition.

In the present invention, the resin composition may further contain conventional additional additives which do not adversely affect the resin composition or the resin coating obtained therefrom. Suitable additives include, for example, those agents that improve the processability or manufacturability of the color modifying composition, or improve specific functional properties or characteristics of the composition or the coating resulting therefrom, such as adhesion to a substrate or an underlying coating. Additives that may be included are, for example, dispersants, defoamers, leveling agents, co-solvents, UV stabilizers, UV absorbers, anti-migration aids, antimicrobial agents, wetting agents, biocides, plasticizers, defoamers, antioxidants, adhesion promoters, or combinations thereof. The amount of each optional ingredient is sufficient to serve its intended purpose, but preferably such amount does not adversely affect the composition or the coating resulting therefrom. In a preferred embodiment of the present invention, the film-forming resin composition comprises a dispersant, defoamer, leveling agent, co-solvent, UV stabilizer, UV absorber or a combination thereof.

In one embodiment according to the invention, the amount of the additional additive is in the range of 0.5 to 10 wt. -% relative to the total weight of the two-component coating composition. In some embodiments, the additional additive may be present in an amount of 0.5-8 wt%, 0.5-7 wt%, 0.5-6 wt%, 0.5-5 wt%, 1-8 wt%, 1-7 wt%, 1-6 wt%, 1-5 wt%, 2-8 wt%, 2-7 wt%, 2-6 wt%, 2-5 wt%, or any wt% within a range defined by any of these values. In a preferred embodiment, the amount of the additional additive is in the range of 2 to 10 wt.%, relative to the total weight of the two-component coating composition.

The preparation of the film-forming resin composition of the present invention may be accomplished using any suitable mixing method known to those of ordinary skill in the art. For example, the resin composition can be prepared by: fluorocarbon resin, hydroxy-functional acrylic resin, pigment/filler, anti-settling agent, diluent and optional additional additives are added to the vessel and the resulting mixture is then stirred well.

Curing agent

The two-component coating composition according to the invention comprises a polyisocyanate as curing agent. The term "polyisocyanate" as used herein refers to a polyisocyanate compound, polyisocyanate oligomer, or combination thereof, containing two or more isocyanate functional groups (NCO) that are capable of chain extension and crosslinking reactions with active hydrogens to form a three-dimensional network structure.

The inventors of the present invention have surprisingly found that a coating composition prepared by simply mixing a film-forming resin composition comprising a hydroxy-functional acrylic resin and a fluorocarbon resin with a polyisocyanate in a substantial excess relative to the film-forming resin as a curing agent of the coating composition not only provides a coating layer having good adhesion, but also allows the polyisocyanate to combine with the active hydrogen in the primer film and the isocyanate itself to undergo dense network crosslinking during the curing process, thereby providing a dense top coating layer capable of strongly adhering to the primer. The two-component coating composition according to the invention is therefore suitable for application over a base coat to form a top coat, having significantly better abrasion and chemical resistance.

Any suitable polyisocyanate may be used as a curing agent according to embodiments of the present invention. Suitable polyisocyanates include aliphatic or cycloaliphatic polyisocyanates, aromatic polyisocyanates, or any combination thereof. The term "aliphatic or alicyclic polyisocyanate" refers to a compound having two or more NCO functional groups in the molecular skeleton, and the NCO functional groups are attached to aliphatic or alicyclic groups, wherein the case where the NCO functional groups are directly attached to the methyl groups of benzyl groups is considered to be attached to aliphatic groups. The term "aromatic polyisocyanate" refers to a compound having two or more NCO functional groups in the molecular skeleton, and the NCO groups are directly attached to aromatic rings. In a preferred embodiment of the present invention, the polyisocyanate is an aliphatic or cycloaliphatic polyisocyanate, whereby the formulated coating may exhibit excellent adhesion.

As examples of suitable polyisocyanate compounds, polyisocyanate compounds such as Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), bis [ isocyanatocyclohexyl ] methane (HMDI), xylylene Diisocyanate (XDI), tetramethylene-m-xylylene diisocyanate (TMXDI), hexahydrotoluene diisocyanate (HTDI), cyclohexane-1, 4-diisocyanate, 4 '-dicyclohexylmethane diisocyanate, cyclopentane-1, 3-diisocyanate, p-phenylene diisocyanate, toluene Diisocyanate (TDI), naphthalene-1, 4-diisocyanate, biphenyl-4, 4' -diisocyanate, benzene-1, 2, 4-triisocyanate, xylene-1, 4-diisocyanate, xylene-1, 3-diisocyanate, diphenylmethane diisocyanate, butane-1, 2, 3-triisocyanate or polymethylene polyphenyl polyisocyanate, dimers or trimers thereof, derivatives thereof, or any combination thereof may be used. As examples of suitable polyisocyanates, commercially available BAYER Bayhydur 305, BAYHYDUR XP 2655, EASAQUA X L600, wanhua 269, bayhdur 401-70, etc. may be used.

In one embodiment of the present invention, the polyisocyanate is selected from the group consisting of Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), bis [ isocyanatocyclohexyl ] methane (HMDI), xylylene Diisocyanate (XDI), tetramethylene-m-xylylene diisocyanate (TMXDI)), hexahydrotoluene diisocyanate (HTDI), dimers or trimers thereof, derivatives thereof, and any combination thereof. In a preferred embodiment of the present invention, the polyisocyanate is selected from Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), dimers or trimers thereof, derivatives thereof or combinations thereof.

In one embodiment of the present invention, the curing agent comprises aliphatic and/or cycloaliphatic polyisocyanates, whereby the formulated coating composition may exhibit longer pot life and excellent workability. Studies have shown that electron withdrawing groups increase the electropositivity of carbon atoms in isocyanate groups, thereby increasing reactivity, while electron donating groups decrease the reactivity of isocyanate groups. Thus, aliphatic and cycloaliphatic isocyanates are less reactive with alcohols than aromatic isocyanates. Preferably, the curing agent of embodiments of the present invention comprises aliphatic and/or cycloaliphatic polyisocyanates containing long aliphatic chains (more than 6 carbon atoms). As an exemplary illustration, tolonate HDT-100 commercially available from Vencorex may be used.

In one embodiment according to the invention, the curing agent has a solids content of 80 to 100% by weight, preferably 90 to 100% by weight.

According to one embodiment of the invention, a method of using a two-part coating composition comprises: the curing agent and film-forming resin composition are simply mixed in a mixing device at a predetermined weight percent prior to application. Optionally, an appropriate colorant is added to the two-part coating composition obtained above to obtain the desired color. The resulting coating composition in the form of a mixture may be applied using a variety of methods familiar to those skilled in the art, including spraying (e.g., air-assisted, airless or electrostatic spraying), brushing, flood coating and dipping. In one embodiment of the invention, the mixed coating composition is applied by spraying. The coating compositions of the present invention can be applied to a variety of wet film thicknesses. The applied coating may be cured by allowing it to air dry or by accelerating the curing using various drying means (e.g., ovens) familiar to those skilled in the art.

According to certain preferred embodiments of the present application, after mixing the film-forming resin composition and the curing agent, the resulting mixture has a solids content of 75 wt% or more, preferably 75-90 wt% solids content, even more preferably up to 92 wt%.

According to certain preferred embodiments of the present application, after mixing the film-forming resin composition and the curing agent, the resulting mixture, after curing at 25 ℃ and 50% relative humidity for 7 days, forms a coating having an abrasion resistance of 0.030g or less, wherein the abrasion resistance is determined after 500 revolutions of the wheel with a weight of 500g according to GB/T1768-2006.

Article of manufacture

Embodiments of the present application also provide an article comprising a substrate; a primer layer coated on at least a portion of a surface of the substrate; a topcoat applied over at least a portion of the surface of the basecoat, wherein the topcoat is derived from the two-component coating composition described above.

The substrate used in embodiments of the present application may be a metal substrate, a wood substrate, a plastic substrate, a glass substrate, a ceramic substrate, or a combination thereof. In a preferred embodiment of the article of the application, the substrate is a metal substrate. As the metal substrate used to make the articles of the present application, any suitable metal substrate known in the art may be used. As an exemplary illustration, the metal substrate is selected from one or more of steel, iron, aluminum, zinc, copper, and alloys.

According to the application, the article may be prepared, for example, by the steps of: (1) providing a polished or grit blasted metal substrate; (2) Sequentially coating and forming one or more primer layers on the metal substrate using a coating and curing process; (2) One or more of the two-component fluorocarbon coating compositions of the present application are sequentially coated and formed on the metal substrate using a coating and curing process to form a topcoat having improved weatherability. Suitable primer layers include, but are not limited to: a polyurethane primer, a nitro primer, an unsaturated polyester primer, a UV primer, an epoxy primer, an acid-cured primer, an aqueous primer, or a combination thereof.

In some embodiments of the present application, metal articles treated via the fluorocarbon coating compositions of the present application may be used in end-use applications including, but not limited to: frozen and non-frozen shipping containers (e.g., dry cargo containers) from suppliers or manufacturers including China International Marine Containers (CIMC), graaff Transportsysteme Gmbh, maersk Line and other suppliers or manufacturers known to those of ordinary skill in the art; chassis, trailers (including semi-trailers), rail vehicles, truck bodies, boats, bridges, building skeletons, and prefabricated or off-the-shelf metal parts that require temporary indoor or outdoor corrosion protection during manufacture. Additional uses include metal corners, channels, beams (e.g., I-beams), pipes, tubes, sheets, or other components that may be welded into these or other metallic articles.

The present disclosure is more particularly described in the following examples that are intended as illustrations only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the examples below are by weight, and all reagents used in the examples are commercially available and can be used directly without further processing.

Examples

The testing method comprises the following steps:

abrasion resistance: the components of the two-component coating composition of the present invention were mixed and cured at 25℃for 7 days at 50% relative humidity to form a coating, and then the resulting coating was rotated 500 turns with a grinding wheel according to GB/T1768-2006 using a weight of 500g to determine the difference in coating weight before and after abrasion.

Solid content: the components of the two-component coating composition of the present invention were mixed, the mixture was baked at 110℃for 1 hour, and then the ratio of the mass of the residue remaining after baking to the original mass of the mixture was calculated, thereby obtaining the mass solids content of the mixture to be measured.

Viscosity: the components of the a-component of the two-component coating composition of the present invention were mixed and the viscosity of the resulting mixture was then tested using a Stormer-type viscometer.

Raw materials:

resin 1: fluorocarbon resin with hydroxyl value of 50-60mg KOH/g and solid content of 50-60;

resin 2: hydroxy-functionalized acrylic resin having a weight average molecular weight of 16,600, a hydroxyl number of 70-80mg KOH/g, a solids content of greater than 70%;

pigment/filler: titanium white and wollastonite;

anti-settling agent 1: silica aerogel with the trade name Aerosil 200;

anti-settling agent 2: polyamide wax with the trade mark of D8650;

control anti-settling agent: bentonite;

reactive diluent: 5300 of Zhejiang Wansheng;

inactive diluent: petroleum resin with weight average molecular weight not more than 2000 g/mol;

curing agent: aliphatic polyisocyanates (HDI uretdiones), tolonate HDT-100 (solids content 90-100%).

Treating a substrate

The steel sheet purchased from the market is subjected to sand blasting to obtain a metal substrate to be used.

Application of coating composition

And (3) applying 2-3 times of epoxy resin primer on the treated metal substrate by a coating mode such as spraying, brushing, roller coating or dip coating, and polishing and flattening the treated metal substrate by 400# abrasive paper after curing, so as to form a bottom coating. The components of the coating compositions in the amounts shown in table 1 below were mixed to form topcoats. The resulting topcoat is then sprayed onto the primed substrate to form a topcoat.

The viscosity test was performed on the a-components of the coating compositions of the examples and comparative examples shown in table 1 below. The two-component coating composition is then tested for mixed solids content according to test standards and the resulting article will be subjected to abrasion and chemical resistance tests. The test results are summarized in table 1.

From the above results, it can be seen that: the two-part coating compositions of examples 1-3 have significantly higher solids content and coatings formed from fluorocarbon coatings formulated as such have significantly better abrasion and chemical resistance. Furthermore, the two-component coating compositions of examples 1-3 have a significantly lower viscosity on the basis of a significantly higher solids content. Furthermore, examples 1 and 2 using specific anti-settling agents (polyamide wax and silica) have significantly better high temperature storage stability than example 3 using bentonite as the anti-settling agent.

In contrast, the two-component coating compositions of comparative examples 1-2 have significantly lower solids content and the abrasion and chemical resistance of the coatings formed from the fluorocarbon coatings so formulated are also significantly lower than the coatings formed from the two-component coating compositions according to the present invention.

While the invention has been described with reference to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the invention as disclosed herein.

Claims

1. A two-part coating composition comprising:

a) A film-forming resin composition comprising a fluorocarbon resin, a hydroxy-functional acrylic resin, a pigment/filler, and optionally additional additives; and

b) A curing agent, including a polyisocyanate,

wherein the molar ratio of-NCO of the polyisocyanate to-OH of the resin component in the film-forming resin composition is in the range of 1.6 to 2.2:1; and is also provided with

Wherein the solid content of the curing agent is in the range of 80-100%.

2. A two-part coating composition according to claim 1, wherein the molar ratio of-NCO of the polyisocyanate to-OH of the resin component in the film-forming resin composition is in the range of 1.8-2.1:1, more preferably in the range of 1.9-2.0:1.

3. The two-part coating composition of claim 1, wherein the curing agent has a solids content in the range of 90-100%.

4. A two-component coating composition according to any one of claims 1 to 3, wherein the fluorocarbon resin has a hydroxyl number in the range of 45-65mg KOH/g, preferably in the range of 50-60mg KOH/g.

5. A two-component coating composition according to any one of claims 1 to 3, wherein the fluorocarbon resin has a solids content in the range of 50-60%.

6. A two-part coating composition according to any one of claims 1 to 3, wherein the fluorocarbon resin comprises polytetrafluoroethylene fluorocarbon resin, polyvinylidene fluoride fluorocarbon resin, polyvinyl fluoride fluorocarbon resin, chlorotrifluoroethylene-vinyl ether fluorocarbon resin, tetrafluoroethylene-vinyl ether fluorocarbon resin or a combination thereof.

7. A two-part coating composition according to any one of claims 1 to 3, wherein the hydroxyl value of the hydroxyl functional acrylic resin is in the range of 70 to 120mgKOH/g, preferably in the range of 60 to 90mgKOH/g, more preferably in the range of 70 to 80 mgKOH/g.

8. A two-component coating composition according to any one of claims 1 to 3, wherein the hydroxyl-functional acrylic resin has a solids content in the range of 70-80%.

9. A two-part coating composition according to any one of claims 1 to 3, wherein the film-forming resin composition further comprises an anti-settling agent, preferably selected from fumed silica, polyethylene wax, polyamide wax or a combination thereof.

10. A two-component coating composition according to any one of claims 1 to 3, wherein the film-forming resin composition further comprises a diluent, preferably the diluent is a reactive diluent or a petroleum resin having a weight average molecular weight of not more than 2000g/mol as a non-reactive diluent.

11. The two-part coating composition of any one of claim 1 to 10, wherein the film-forming resin composition comprises, based on the total weight of the film-forming resin composition,

30-40 wt% of the fluorocarbon resin;

10-15 wt% of the hydroxy-functionalized acrylic resin;

35-45 wt% of the pigment/filler

0.5-3 wt% of the anti-settling agent;

2-10 wt% of the diluent; and

0-10 wt% of the additional additive comprising a dispersant, a defoamer, a leveling agent, a solvent, or a combination thereof.

12. The two-part coating composition of claim 1, wherein the polyisocyanate is selected from the group consisting of Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), bis [ isocyanatocyclohexyl ] methane (HMDI), toluene Diisocyanate (TDI), xylylene Diisocyanate (XDI), tetramethylene-m-xylylene diisocyanate (TMXDI), hexahydrotoluene diisocyanate (HTDI), dimers or trimers thereof, derivatives thereof, and any combination thereof, preferably the polyisocyanate is selected from the group consisting of Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), dimers or trimers thereof, derivatives thereof, and any combination thereof.

13. A two-component coating composition according to any one of claims 1 to 12, wherein, after mixing the film-forming resin composition and the curing agent, the resulting mixture has a solids content of 75% by weight or more, preferably 75-90% by weight.

14. The two-part coating composition of any one of claims 1 to 12, wherein, after mixing the film-forming resin composition and the curing agent, the resulting mixture has an abrasion resistance of 0.030g or less after curing at 25 ℃ for 7 days at 50% relative humidity.

15. A two-component coating composition according to any one of claims 1 to 12 for use as a top coat.

16. An article of manufacture comprising

A substrate;

a primer layer coated on at least a portion of a surface of the substrate; and

a top coat layer applied over the base coat layer,

wherein the topcoat is formed from the two-part coating composition of any one of claims 1 to 15.

17. The article of claim 16, wherein the primer is selected from the group consisting of a polyurethane primer, an epoxy primer, a nitro primer, an unsaturated polyester primer, an acid-cured primer, an aqueous primer, and any combination thereof.

18. The article of claim 16, wherein the substrate comprises a metal substrate, a wood substrate, a plastic substrate, a glass substrate, a ceramic substrate, or a combination thereof.