Modified polycarbodiimide compound, coating composition and coated product

Abstract

The present invention relates to a modified polycarbodiimide compound, a coating composition and a coated product. The modified polycarbodiimide compound of the present invention has a polymer backbone containing an N=C=N structural unit and a structural unit, wherein the N=C=N structural unit is a nitrogen heterocycle connected to the polymer backbone, and the nitrogen heterocycle is fused or chemically bonded to an optionally substituted or optionally nitrogen-containing benzene ring. Compared with an unmodified polycarbodiimide compound, the modified polycarbodiimide compound described herein can significantly improve the chemical resistance of a cured coating.

Description

Technical Field

[0001] The present invention relates to a modified polycarbodiimide compound, a coating composition comprising the modified polycarbodiimide compound, and a coated article comprising a cured coating formed from the coating composition. Background Art

[0002] In the coatings industry, crosslinking agents are widely used to accelerate the crosslinking of polymers and improve the hardness and chemical resistance of paint films. A class of crosslinking agents that have shown excellent performance in currently known coating formulations is aziridine crosslinking agents. However, aziridine crosslinking agents are allergenic substances and are toxic.

[0003] With the increasing concern about health and environmental issues, people are increasingly hoping to reduce or even avoid the use of allergenic substances in coatings. Polycarbodiimide has received widespread attention due to its advantages such as non-toxicity, VOC-free, and high adhesion. However, compared with conventional crosslinking agents such as aziridine and silane compounds, the properties of the paint film obtained using polycarbodiimide are significantly poorer, especially chemical resistance (such as water resistance). Some researchers have attempted to improve the properties of the paint film by modifying carbodiimide compounds. However, most of these schemes involve complex modification processes, and have low yields, difficult to control product quality, and a small scope of application, so the cost is high, which greatly limits the scope of application and application prospects of polycarbodiimide compounds in the market. Summary of the invention

[0004] Therefore, the coating industry still needs a crosslinking agent that is low-cost, easy to operate, safe and non-toxic, contains less or even no allergenic substances, and can form a dense paint film with excellent chemical resistance.

[0005] The above objectives can be achieved by the modified polycarbodiimide compounds described herein.

[0006] The first aspect of the present application provides a modified polycarbodiimide compound having a -N=C=N- structural unit and The polymer backbone of the structural unit, wherein the is a nitrogen heterocycle attached to the polymer backbone, which is fused or chemically linked to an optionally substituted or optionally aza benzene ring.

[0007] The second aspect of the present application provides a coating composition comprising component A) and component B), wherein component A) comprises a film-forming resin, a cosolvent and optionally an additive; and component B) comprises a crosslinking agent, wherein the crosslinking agent comprises the modified polycarbodiimide compound described herein.

[0008] A third aspect of the present application provides a coated product comprising a substrate and a cured coating formed from the coating composition described herein and coated on the substrate.

[0009] The present application also provides the use of the modified polycarbodiimide compound described herein in a coating composition. The coating film formed by the coating composition has excellent chemical resistance (eg water resistance).

[0010] The inventors have found that the modified polycarbodiimide compound described herein can form a dense paint film after the coating composition is cured, and improve the chemical resistance, especially water resistance, of the paint film. The modified polycarbodiimide compound has excellent stability. In addition, the modified polycarbodiimide compound described herein is a non-allergenic substance and has low VOC. Therefore, the technical solution of the present application can also have the advantages of simple operation, safety, environmental protection, and low cost.

[0011] It is highly unexpected that the modified polycarbodiimide compounds or coating compositions described herein can reduce or even avoid the use of allergenic substances while achieving improved chemical resistance.

[0012] The details of one or more embodiments of the invention are set forth in the description which follows. Other features, objects, and advantages of the invention will become apparent from the description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A comparison of Fourier transform infrared spectra (FT-IR) of an unmodified polycarbodiimide compound (PCDI) and a modified polycarbodiimide compound (PCDI#-C) according to one embodiment of the present invention is shown.

[0014] Figure 2 The DSC curve of benzotriazole is shown.

[0015] Figure 3 DSC curves of an unmodified polycarbodiimide compound (PCDI) and a modified polycarbodiimide compound (PCDI#-C) according to one embodiment of the present invention are shown.

[0016] Figure 4 The water resistance photographs of the paint films prepared with the unmodified polycarbodiimide compound (PCDI), the modified polycarbodiimide compound (PCDI#-C) according to one embodiment of the present invention, and PCDI#-C after heat storage for one month are shown. DETAILED DESCRIPTION

[0017] definition

[0018] As used herein, "a", "an", "the", "at least one" and "one or more" and the absence of quantifiers may be used interchangeably unless otherwise indicated. Thus, for example, a coating composition comprising "an" additive may be interpreted to mean that the coating composition comprises "one or more" additives. Unless otherwise indicated herein, the use of the singular form herein is intended to include the plural form.

[0019] Where a composition is described as comprising or including specific components, it is contemplated that optional components not contemplated by the present invention are not excluded from the composition, and that the composition may consist of or be composed of the contemplated components; or where a method is described as comprising or including specific process steps, it is contemplated that optional process steps not contemplated by the present invention are not excluded from the method, and that the method may consist of or be composed of the contemplated process steps.

[0020] For the sake of simplicity, only some numerical ranges are explicitly disclosed herein. However, it should be understood that any range formed by combining any lower limit with any upper limit belongs to the content explicitly disclosed in the present invention; any range formed by combining any lower limit with other lower limits also belongs to the content explicitly disclosed in the present invention, and similarly, any range formed by combining any upper limit with other upper limits also belongs to the content explicitly disclosed in the present invention.

[0021] Unless otherwise indicated, each point or single value between the endpoints of a range is included in the range. For example, a range of 1 to 5 includes the values ​​1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. Moreover, a disclosed numerical range includes all subset ranges within the broader range, for example, a range of 1 to 5 includes subranges 1 to 4, 1.5 to 4.5, 1 to 2, etc. Thus, each point or single value can be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits, and the resulting range belongs to the content clearly disclosed in the present invention.

[0022] In the context of describing that a composition does not contain a certain ingredient, the term "does not contain" means that the composition does not contain the intentionally added ingredient. Considering the complexity of the specific composition of each component in the actual formulation process, the phrase "does not contain a certain ingredient" can be understood as the composition containing less than 1% by weight of the ingredient based on the total weight of the composition, more preferably less than 0.5% by weight, even more preferably less than 0.2% by weight, and most preferably less than 0.1% by weight.

[0023] The coating compositions described herein can be single component or multi-component. In the context of a "multi-component" coating composition, the term "multi-component" means that the coating composition includes two or more components that are stored or packaged separately and then mixed together before being applied to a substrate. In some embodiments of the present invention, the multi-component coating composition is composed of two components (including a film-forming component and a crosslinker component) and can therefore be referred to as a two-component coating composition.

[0024] The coating composition described herein can be a "water-based" coating composition. The term "water-based" refers to that the solvent or carrier fluid of the coating composition mainly or primarily comprises water. For example, in some embodiments, based on the gross weight of the solvent or carrier fluid, the solvent or carrier fluid comprises at least about 50 wt %, preferably at least about 60 wt %, more preferably at least 70 wt % and about 100 wt % water at most. For example, based on the gross weight of the solvent or carrier fluid, the solvent or carrier fluid comprises about 80 wt %, about 85 wt % or about 90 wt % water.

[0025] The term "sensitizing substance" as used herein refers to a substance that may cause sensitization through skin contact. In particular, a "sensitizing substance" is a substance that is clearly stated as "having a sensitizing effect" in the Material Safety Data Sheet (MSDS). Examples of sensitizing substances include aziridine and substances with similar structures.

[0026] As used herein, the term "dispersion" conforms to the definition in the IUPAC Compendium of Chemical Terminology (2007), which defines a dispersion as a material comprising more than one phase, wherein at least one phase consists of finely divided phase domains, typically in the colloidal size range, distributed throughout a continuous phase domain.

[0027] When used in this article, the term "aqueous dispersion containing polymer particles" refers to a stable dispersion of a synthetic resin (i.e., a polymer) in the form of particles in an aqueous liquid medium, optionally with the aid of a suitable dispersing aid such as a surfactant, a cosolvent. Therefore, in this application, when used for a polymer, unless otherwise stated, the terms "aqueous latex" and "aqueous dispersion" can be used interchangeably. Methods for preparing aqueous latexes are known in the art, for example, they can be prepared using emulsion polymerization processes known to those skilled in the art. The emulsion polymerization preparation process generally comprises the following steps: optionally under the action of a suitable emulsifier and / or a dispersion stabilizer and with the aid of stirring, the polymerizable monomer is dispersed into an emulsion in water, and the polymerization of the monomer is initiated, for example, by adding an initiator. In the present invention, the polymer particles can be modified by, for example, modification of organic functional groups (including, but not limited to, carboxyl, hydroxyl, amino, isocyanate, sulfonic acid, etc.) to obtain an aqueous latex with desired properties (e.g., dispersibility). Therefore, in the present invention, the term "aqueous latex" includes not only dispersions of unmodified polymer particles in an aqueous medium, but also dispersions of polymer particles modified with organic functional groups in an aqueous medium.

[0028] The term "alkyl" as used herein refers to a straight or branched hydrocarbon containing 1 to 10 carbon atoms, preferably 1, 2, 3, 4, 5 or 6 carbons. Representative examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, n-octyl, n-nonyl and n-decyl. Each carbon atom of the alkyl group may be substituted by 0, 1 or 2 substituents selected from acyl, acyloxy, alkoxy, alkoxyalkoxy, alkoxyalkyl, alkoxycarbonyl, alkoxyimino, alkoxysulfonyl, alkylcarbonyl, alkylsulfonyl, amide, carboxyl, cyano, cycloalkyl, fluoroalkoxy, formyl, halogenated alkoxy, halogenated alkyl, halogen, hydroxyl, hydroxyalkyl, sulfhydryl, nitro, oxo and alkylthio.

[0029] The term "alkylamino" as used herein refers to an alkyl group, as defined herein, appended to the parent molecular moiety through an NH group. Representative examples of alkylamino include, but are not limited to, methylamino, ethylamino, isopropylamino and butylamino.

[0030] The term "alkylcarbonyl" as used herein refers to an alkyl group, as defined herein, appended to the parent molecular moiety through a carbonyl group. Representative examples of alkylcarbonyl include, but are not limited to, methylcarbonyl, ethylcarbonyl, isopropylcarbonyl, n-propylcarbonyl, and the like.

[0031] The term "alkylsulfonyl" as used herein refers to an alkyl group, as defined herein, appended to the parent molecular moiety through a sulfonyl group. Representative examples of alkylsulfonyl include, but are not limited to, methylsulfonyl and ethylsulfonyl.

[0032] The term "alkoxy" as used herein refers to an alkyl group, as defined herein, attached to the parent molecular moiety through an oxygen atom. Representative examples of alkoxy include, but are not limited to, methoxy, ethoxy, propoxy, 2-propoxy, butoxy, tert-butoxy, pentoxy, and hexoxy.

[0033] The term "alkoxycarbonyl" as used herein refers to an alkoxy group, as defined herein, appended to the parent molecular moiety through a carbonyl group. Representative examples of alkoxycarbonyl include, but are not limited to, methoxycarbonyl, ethoxycarbonyl, isopropoxycarbonyl and tert-butoxycarbonyl.

[0034] The term "alkoxyalkyl" as used herein, refers to an alkoxy group, as defined herein, appended to the parent molecular moiety through an alkyl group. Representative examples of alkoxyalkyl include, but are not limited to, tert-butoxymethyl, 2-ethoxyethyl, 2-methoxyethyl and methoxymethyl.

[0035] The term "cycloalkyl" as used herein refers to a saturated cyclic hydrocarbon group containing 3-8 carbons. Examples of cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl. Each carbon atom of cycloalkyl may be substituted by 0, 1 or 2 substituents selected from acyl, acyloxy, alkenyl, alkoxy, alkoxyalkoxy, alkoxyalkyl, alkoxycarbonyl, alkoxyimino, alkoxysulfonyl, alkyl, alkylcarbonyl, alkylsulfonyl, alkynyl, amide, carboxyl, cyano, cycloalkyl, fluoroalkoxy, formyl, halogenated alkoxy, haloalkyl, halogen, hydroxyl, hydroxyalkyl, sulfydryl, nitro and alkylthio.

[0036] The term "acyl" as used herein refers to an alkyl group, as defined herein, attached to the parent molecular moiety through a carbonyl group. Representative examples of acyl include, but are not limited to, acetyl, 1-oxopropyl, 2,2-dimethyl-1-oxopropyl, 1-oxobutyl and 1-oxopentyl.

[0037] The term "halogen" or "halo" refers to Cl, Br, I or F.

[0038] Term used herein " haloalkyl " refers to at least one halogen defined herein that is connected to the parent molecular moiety through alkyl defined herein.Representative examples of haloalkyl include but are not limited to chloromethyl, 2-fluoroethyl, trifluoromethyl, pentafluoroethyl and 2-chloro-3-fluoropentyl.

[0039] The term "haloalkoxy" as used herein, means at least one halogen, as defined herein, appended to the parent molecular moiety through an alkoxy group, as defined herein. Representative examples of haloalkoxy include, but are not limited to, 2-fluoroethoxy, trifluoromethoxy, and pentafluoroethoxy.

[0040] The term "aryl" or "aromatic group" as used herein refers to optionally substituted phenyl, bicyclic aryl or tricyclic aryl. Bicyclic aryl is connected to the parent molecular moiety through any carbon atom contained in the bicyclic aryl. Representative examples of bicyclic aryl include but are not limited to dihydroindenyl, indenyl, naphthyl, dihydronaphthyl and tetrahydronaphthyl. Tricyclic aryl is a tricyclic aryl ring system, such as anthracene or phenanthrene, a bicyclic aryl fused to a cycloalkyl, a bicyclic aryl fused to a cycloalkenyl, and a bicyclic aryl fused to a phenyl. Tricyclic aryl is connected to the parent molecular moiety through any carbon atom contained in the tricyclic aryl. Representative examples of tricyclic aryl rings include but are not limited to anthracenyl, phenanthryl, azulenyl, dihydroanthracenyl, fluorenyl and tetrahydrophenanthryl.

[0041] The carbon atoms of the aryl group may be substituted with one or more substituents independently selected from acyl, acyloxy, alkenyl, alkoxy, alkoxyalkoxy, alkoxyalkyl, alkoxycarbonyl, alkoxyimino, alkoxysulfonyl, alkyl, alkylcarbonyl, alkylsulfonyl, alkynyl, amide, carboxyl, cyano, cycloalkyl, fluoroalkoxy, formyl, haloalkoxy, haloalkyl, halogen, hydroxyl, hydroxyalkyl, mercapto, nitro and alkylthio. In the case where the aryl group is phenyl, the number of substituents is 0, 1, 2, 3, 4 or 5. In the case where the aryl group is a bicyclic aryl group, the number of substituents is 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. In the case where the aryl group is a tricyclic aryl group, the number of substituents is 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9.

[0042] The term "aralkyl" as used herein, refers to an aryl group, as defined herein, appended to the parent molecular moiety through an alkyl group, as defined herein. Representative examples of aralkyl include, but are not limited to, benzyl, 2-phenylethyl and 3-phenylpropyl.

[0043] The term "heteroaryl" as used herein can be a monocyclic or bicyclic ring. The carbon in the "heteroaryl" can be optionally substituted by one or more substituents, and the substituents are independently selected from acyl, acyloxy, alkenyl, alkoxy, alkoxyalkoxy, alkoxyalkyl, alkoxycarbonyl, alkoxyimino, alkoxysulfonyl, alkyl, alkylcarbonyl, alkylsulfonyl, alkynyl, amide, carboxyl, cyano, cycloalkyl, fluoroalkoxy, formyl, halogenated alkoxy, halogenated alkyl, halogen, hydroxyl, hydroxyalkyl, sulfhydryl, nitro and alkylthio. Monocyclic heteroaryl or 5- or 6-membered heteroaromatic ring is substituted by 0, 1, 2, 3, 4 or 5 substituents. Bicyclic heteroaryl or 8- to 12-membered bicyclic heteroaromatic ring is substituted by 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9 substituents. The heteroaryl of the present invention can exist as tautomers.

[0044] When a group is described as "optionally substituted," the group may be unsubstituted or substituted with one or more of the specified substituents.

[0045] The terms "preferred" and "preferably" refer to embodiments of the present invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. In addition, the recitation of one or more preferred embodiments does not mean that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present invention.

[0046] According to a first aspect of the present invention, a modified polycarbodiimide compound is provided. The modified polycarbodiimide compound described herein is modified with a nitrogen-containing condensed ring compound or an aromatic-substituted nitrogen-containing heterocyclic compound. The modified polycarbodiimide compound has a -N=C=N- structural unit and The structural unit of the polymer backbone. It is a nitrogen heterocycle attached to the polymer backbone, which is fused or chemically linked to an optionally substituted or optionally aza benzene ring.

[0047] The wavy lines indicate connections to other atoms in the ring. The wavy line in represents the connection between the nitrogen atom and other atoms in the nitrogen heterocycle, and the nitrogen atom and other atoms in the nitrogen heterocycle together form the nitrogen heterocycle through the connection shown. That is, the nitrogen atom is an atom in the nitrogen heterocycle, and the nitrogen heterocycle is connected to the polymer main chain through the nitrogen atom.

[0048] Therefore, in an exemplary embodiment, The structural unit can also be expressed as In this structural unit, The nitrogen heterocyclic ring in the ring is connected to the polymer backbone via a chemical bond on the nitrogen atom.

[0049] The modified polycarbodiimide compound herein contains a -N=C=N- structural unit in the polymer main chain. The -N=C=N- functional group can react with reactive groups such as carboxyl, amino, hydroxyl and thiol in the resin component. In particular, the -N=C=N- functional group can react with the carboxyl group in the resin component.

[0050] Preferably, the modified polycarbodiimide compound has more than 2 carbodiimide groups (-N=C=N-) or carbodiimide derivative structures. More preferably, the modified polycarbodiimide compound has more than 3 carbodiimide groups. For example, in some exemplary embodiments, the modified polycarbodiimide compound has 3 to 7 carbodiimide groups. The modified polycarbodiimide compound may include a modified aliphatic carbodiimide compound, a modified alicyclic carbodiimide compound, and a modified aromatic carbodiimide compound.

[0051] It can be seen that the modified polycarbodiimide compound herein contains -N=C=N- structural units and The inventors have found that by using this specific combination of structural units, the modified polycarbodiimide compound can have excellent cross-linking properties and improve the chemical resistance of the cured coating.

[0052] In some preferred embodiments, the -N=C=N- structural unit on the polymer backbone is The molar ratio of the structural units is in the range of about 100:80 to 100:10. Preferably, the -N=C=N- structural unit and The molar ratio of the structural unit is about 100:15 or less, more preferably about 100:20 or less, and still more preferably about 100:25 or less. The molar ratio of the structural units is about 100:70 or greater, more preferably about 100:65 or greater, and still more preferably about 100:60 or greater. For example, the -N=C=N- structural unit and The molar ratio of the structural units can be about 100:30, 100:40 or 100:50. The inventors surprisingly found that by controlling the -N=C=N- structural unit in the modified polycarbodiimide compound and The relative content of the structural units can further improve the chemical resistance of the cured coating.

[0053] In some embodiments, the number average molecular weight of the modified polycarbodiimide compound is in the range of about 1500 to 5000 g / mol. Preferably, the number average molecular weight of the modified polycarbodiimide compound is about 1800 g / mol or greater, more preferably about 1900 g / mol or greater. Preferably, the number average molecular weight of the modified polycarbodiimide compound is about 4500 g / mol or less, more preferably about 4000 g / mol or less. For example, the number average molecular weight of the modified polycarbodiimide compound can be about 2000 g / mol, about 2100 g / mol, about 2200 g / mol, about 2300 g / mol, about 2500 g / mol, about 3000 g / mol or about 3500 g / mol. As an example, the number average molecular weight of the modified polycarbodiimide compound can be adjusted by selecting the type of polycarbodiimide raw material and the relative amount of the modifier and the polycarbodiimide raw material. Other technical means that can be easily thought of by those skilled in the art can also be used to adjust the number average molecular weight of the compound.

[0054] In the modified polycarbodiimide compound In the structural unit, the nitrogen heterocyclic ring attached to the polymer backbone It can be an aza-fused ring group or an aza-heterocyclic group substituted with an aromatic group. In some preferred embodiments, in the modified polycarbodiimide compound, The structural unit can be selected from More preferably, The structural unit can be selected from One or more of .

[0055] exist In the structural unit, the benzene ring can be optionally substituted or optionally aza. In some embodiments, the benzene ring is unsubstituted. In some embodiments, the benzene ring is not aza. In some preferred embodiments, the benzene ring is unsubstituted and not aza.

[0056] In other embodiments, the phenyl ring is substituted. For example, the phenyl ring can be replaced by one or more of OH, alkyl, alkylamino, alkylcarbonyl, alkylsulfonyl, alkoxy, alkoxycarbonyl, alkoxyalkyl, alkoxyimino, alkoxysulfonyl, alkylthio, cycloalkyl, acyl, halogen, haloalkyl, haloalkoxy, hydroxyalkoxy, aryl, aralkyl and heteroaryl. Preferably, the phenyl ring can be replaced by one or more of alkyl, alkylamino, cycloalkyl, halogen, haloalkyl, haloalkoxy, aryl, aralkyl and heteroaryl.

[0057] In some embodiments, the benzene ring may be substituted with one or more nitrogens. Preferably, the benzene ring is substituted with one or two nitrogens.

[0058] In some embodiments, the modified polycarbodiimide compound can be prepared by reacting a polycarbodiimide compound with an aza-condensed ring compound or an aromatic-substituted nitrogen heterocyclic compound, wherein the aza-condensed ring compound or the aromatic-substituted nitrogen heterocyclic compound has a ring containing an -NH- bond. Therefore, a method for preparing a modified polycarbodiimide compound is also provided herein, comprising reacting a polycarbodiimide compound with an aza-condensed ring compound or an aromatic-substituted nitrogen heterocyclic compound, wherein the aza-condensed ring compound or the aromatic-substituted nitrogen heterocyclic compound has a ring containing an -NH- bond.

[0059] It is known in the art that nitrogen-containing condensed ring compounds and aromatic-substituted nitrogen heterocyclic compounds have special π-electron aromatic rings. In this article, in addition to the special π-electron aromatic ring, the nitrogen-containing condensed ring compounds and aromatic-substituted nitrogen heterocyclic compounds used to prepare the modified polycarbodiimide compound also have a ring containing an -NH- bond. The nitrogen-containing condensed ring compounds and aromatic-substituted nitrogen heterocyclic compounds can also be amine compounds containing a benzene ring.

[0060] Without wishing to be bound by theory, it is believed that the -NH- bond in the nitrogen-fused ring compound or the aromatic-substituted nitrogen heterocyclic compound reacts with the -N=C=N- in the polycarbodiimide compound, thereby connecting the aromatic group and the nitrogen heterocyclic ring to the polymer backbone. After the coating composition containing the modified polycarbodiimide compound and the film-forming resin or emulsion is cured to form a coating, the nitrogen-fused ring group or the aromatic-substituted nitrogen heterocyclic group is included in the paint film by chemical bonding, thereby increasing the hydrophobicity and compactness of the paint film, thereby improving the resistance of the paint film.

[0061] In some embodiments, the nitrogen heterocyclic compound and the aromatic group-substituted nitrogen heterocyclic compound may have a five-membered nitrogen heterocyclic structure or a six-membered nitrogen heterocyclic structure. That is, in the modified polycarbodiimide compound, The nitrogen heterocycle may be an optionally substituted five-membered nitrogen heterocycle or a six-membered nitrogen heterocycle.

[0062] In some preferred embodiments, the nitrogen heterocyclic compound has a five-membered nitrogen heterocyclic structure. The nitrogen heterocyclic structure may have one or more nitrogen atoms. In some preferred embodiments, The nitrogen heterocycle in is a five-membered nitrogen heterocycle. The ring nitrogen atom connected to the polymer backbone is in the five-membered nitrogen heterocycle. Preferably, the nitrogen heterocycle may have 2 to 3 nitrogen atoms, more preferably 3 nitrogen atoms.

[0063] The five-membered nitrogen heterocyclic ring or six-membered nitrogen heterocyclic ring structure can be fused or chemically bonded to the benzene ring. In the nitrogen-fused ring compound or the aromatic-substituted nitrogen heterocyclic compound, the benzene ring can be optionally substituted or optionally aza. In some embodiments, the benzene ring is unsubstituted. In some embodiments, the benzene ring is not aza. In some preferred embodiments, the benzene ring is unsubstituted and not aza.

[0064] In other embodiments, in the nitrogen heterocyclic compound or the aromatic substituted nitrogen heterocyclic compound, the benzene ring is substituted. For example, the benzene ring can be substituted by one or more of OH, alkyl, alkylamino, alkylcarbonyl, alkylsulfonyl, alkoxy, alkoxycarbonyl, alkoxyalkyl, alkoxyimino, alkoxysulfonyl, alkylthio, cycloalkyl, acyl, halogen, haloalkyl, haloalkoxy, hydroxyalkoxy, aryl, aralkyl and heteroaryl. Preferably, the benzene ring can be substituted by one or more of alkyl, alkylamino, cycloalkyl, halogen, haloalkyl, haloalkoxy, aryl, aralkyl and heteroaryl.

[0065] In some embodiments, in the nitrogen-fused ring compound or the aromatic nitrogen-substituted heterocyclic compound, the benzene ring may be substituted with one or more nitrogens. Preferably, the benzene ring is substituted with one or two nitrogens.

[0066] In the aza-fused ring compound, the aza-fused ring is fused to a benzene ring. In some embodiments, the aza-fused ring compound may include benzotriazole Benzimidazole Indole Purine and phthalimide Preferably, the aza-fused ring compound comprises any combination of one or more of benzotriazole, benzimidazole and indole. More preferably, the aza-fused ring compound comprises benzotriazole and / or benzimidazole. Particularly preferably, the aza-fused ring compound comprises benzotriazole. The benzene ring in the aza-fused ring compound may be optionally substituted or optionally aza. The preferred manner of the substituent is as described above.

[0067] In the aromatic substituted nitrogen heterocyclic compound, the nitrogen heterocyclic ring may be chemically bonded to the aromatic group. The aromatic group preferably has one or more benzene ring structures. Preferably, the aromatic substituted nitrogen heterocyclic compound may be a phenyl substituted nitrogen heterocyclic compound. In some embodiments, the aromatic substituted nitrogen heterocyclic compound may include 2-phenylimidazole and 2-phenyl-4-methylimidazole In the aromatic substituted nitrogen heterocyclic compound, the benzene ring may be optionally substituted or optionally aza. The preferred form of the substituent is as described above.

[0068] It is worth noting that after the polycarbodiimide compound reacts with the nitrogen-containing condensed ring compound or the aromatic-substituted nitrogen-containing heterocyclic compound, the obtained modified polycarbodiimide compound still contains -N=C=N- groups, so that it still has the function of a crosslinking agent. Therefore, it can also be considered that the modified polycarbodiimide compound in this article is partially modified.

[0069] Furthermore, the inventors have found that the chemical resistance of the cured coating can be further improved by adjusting the degree of modification or adjusting the relative content of the polycarbodiimide compound and the nitrogen-containing condensed ring compound or the aromatic-substituted nitrogen-containing heterocyclic compound.

[0070] In some embodiments, the weight ratio of the polycarbodiimide compound to the aza-condensed ring compound or the aromatic substituted nitrogen heterocyclic compound may preferably be about 100:3 or less, more preferably about 100:4 or less, and even more preferably about 100:5 or less. The weight ratio of the polycarbodiimide compound to the aza-condensed ring compound or the aromatic substituted nitrogen heterocyclic compound may preferably be about 100:20 or less, more preferably about 100:17 or less, and even more preferably about 100:15 or less. For example, the weight ratio of the polycarbodiimide compound to the aza-condensed ring compound or the aromatic substituted nitrogen heterocyclic compound may be about 100:6, 100:8, 100:10, 100:12 or 100:14. These values ​​are merely exemplary. Those skilled in the art can reasonably understand that the weight ratio of the polycarbodiimide compound to the aza-condensed ring compound or the aromatic substituted nitrogen heterocyclic compound may also be any value between the above values. Furthermore, ranges defined by any of these numerical values ​​also belong to the content disclosed herein.

[0071] The inventors have found that the modified polycarbodiimide compounds described herein can improve the resistance of the cured coating. The improvement in resistance includes the improvement of chemical resistance, such as the improvement of at least one of alcohol resistance, acid resistance, water resistance, and heat resistance, especially the improvement of water resistance. By adopting some preferred embodiments described herein, the paint film obtained has a resistance comparable to or even better than that of a cross-linking agent (such as PCDI), and by adjusting the degree of modification, the chemical resistance of the cured coating can be further improved. In addition, in some preferred embodiments, the modified polycarbodiimide compound also has excellent stability, and still has a good cross-linking effect after being stored for a certain period of time. At the same time, the formed cured coating also has excellent stability in terms of water resistance. These effects are unexpected by those skilled in the art.

[0072] The second aspect of the present application provides a coating composition comprising component A) and component B), wherein component A) comprises a film-forming resin, a cosolvent and optionally an additive; and component B) comprises a crosslinking agent, wherein the crosslinking agent comprises the modified polycarbodiimide compound described herein.

[0073] In some embodiments, based on the total weight of the coating composition, the amount of the modified polycarbodiimide compound can be about 0.3 wt % or more, about 0.4 wt % or more, about 0.5 wt % or more. Based on the total weight of the coating composition, the amount of the modified polycarbodiimide compound can be about 5 wt % or less, about 4 wt % or less, about 3 wt % or less. For example, based on the total weight of the coating composition, the amount of the modified polycarbodiimide compound can be about 0.8 wt %, 1 wt %, 1.2 wt %, 1.5 wt %, 1.8 wt %, 2 wt % or 2.5 wt %. Preferably, the amount of the modified polycarbodiimide compound in the coating composition can be about 0.5 wt % to 2.0 wt %, more preferably about 1 wt % to 1.5 wt %. By adopting the modified polycarbodiimide compound of the above amount, excellent coating properties, such as an excellent combination of curing effect and resistance, can be obtained simultaneously.

[0074] In this article, film-forming resin refers to a resin that can form a paint film when the coating is cured. Various types of film-forming resins can be used. Examples of common film-forming resins include self-crosslinking resins, polyurethane resins, polyurethane acrylate resins, alkyd resins, acrylic resins, isocyanate resins, polyurethane acrylate modified epoxy resins, unsaturated polyester resins, acrylic epoxy resins and nitro resins. Preferably, the film-forming resin comprises one or more of self-crosslinking resins, polyurethane resins, polyurethane acrylate resins, alkyd resins and acrylic resins. More preferably, the film-forming resin comprises one or more of self-crosslinking resins, polyurethane resins and polyurethane acrylate resins.

[0075] In some embodiments, the film-forming resin comprises a self-crosslinking resin. A self-crosslinking resin refers to a resin that can be crosslinked without the addition of a crosslinking agent. Examples of self-crosslinking resins include self-crosslinking polyester resins, self-crosslinking polyamide resins, self-crosslinking acrylic resins, self-crosslinking epoxy resins, and self-crosslinking olefin resins. Preferably, the self-crosslinking resin comprises a self-crosslinking acrylic resin. In an exemplary embodiment, the self-crosslinking resin comprises an acrylic siloxane resin.

[0076] Self-crosslinking resin can be made from monomers with self-crosslinking groups. For example, self-crosslinking acrylic resin can be made from functional monomers containing ketocarbonyl or epoxy groups and hydrazide compounds. Examples of functional monomers containing ketocarbonyl or epoxy groups can include, for example, diacetone acrylamide (DAAM), methyl vinyl ketone, acetoacetoxyethyl methacrylate (AAEM), glycidyl methacrylate (GMA) and (meth) acetamidoethyl acrylate, etc. In some preferred embodiments, the functional monomer containing ketocarbonyl includes one or more of DAAM, AAEM and GMA. More preferably, the functional monomer containing ketocarbonyl includes DAAM, AAEM or a combination of the two.

[0077] Since DAAM has low toxicity and simple synthetic raw materials, and is particularly beneficial for enhancing the adhesion performance of coatings, DAAM is currently mostly used as a functional monomer containing a ketocarbonyl group. In an exemplary embodiment, the functional monomer containing a ketocarbonyl group includes DAAM. In another exemplary embodiment, the functional monomer containing a ketocarbonyl group includes AAEM.

[0078] Examples of hydrazide compounds may include, for example, adipic acid dihydrazide (ADH), succinic acid dihydrazide, carbonate dihydrazide, oxalic acid dihydrazide, N(CH2CH2CONHNH2)3 and (H2NHNCOCH2CH2)2NCH2CH2N(CHCHCONHNH2)2 and polymer polyhydrazide.

[0079] Self-crosslinking acrylic resin can be obtained by a synthetic method. For example, diacetone acrylamide (DAAM), methyl methacrylate (MMA), butyl acrylate (BA) and methacrylic acid (MAA) are used as comonomers to synthesize self-crosslinking closed polyacrylate emulsion (PAE) by semi-continuous seed emulsion polymerization.

[0080] Self-crosslinking acrylic resins are commercially available, for example, as self-crosslinking acrylic emulsions. Exemplary commercially available self-crosslinking acrylic emulsions include, but are not limited to, ROSHIELD TM 3311 and ROSHIELD TM 3188.

[0081] In some embodiments, the film-forming resin comprises a polyurethane resin. Various types of polyurethane resins can be used. The polyurethane resin can be in the form of a polyurethane dispersion (PUD), for example, the U series (such as U 6150, U 9380 and U 9900) available from Alberdingk Boley, Inc., the Bayhydrol series (such as Bayer) available from Bayer, UH 2558 and UH 2606) and Dispercoll series, NeoRez series purchased from DSM (such as R-2180, R-2005, R-9029 and R-2190), the SYNTEGRA series available from Dow, or the Sancure series (such as Sancure 843, Sancure 898, and Sancure 12929) available from Lubrizol, Inc. (Cleveland, OH).

[0082] In some embodiments, the film-forming resin comprises a polyurethane acrylate (PUA) resin. Various types of polyurethane acrylate resins can be used. As examples, the Hybridur series (such as Hybridur 870 and Hybridur 878) available from Air Products, Inc., the APU series (APU 10140, APU 10600, and APU 10620) available from Alberdingk Boley, Inc., the APU series (APU 10140, APU 10600, and APU 10620) available from DSM, and the APU series (such as APU 10140, APU 10600, and APU 10620) available from DSM can be used. series (NeoPac R-9036 and NeoPac E-129), CONFON 7005 purchased from Xiangfeng Chemical, PROSPERSE purchased from DOW TM 100.

[0083] Preferably, the film-forming resin has a side chain containing a ketocarbonyl group (-(C=O)-) and / or an epoxy group. Preferably, the side chain of the polymer contains a ketocarbonyl group.

[0084] The amount of the film-forming resin may be about 45-95 wt %, preferably about 50-90 wt %, more preferably about 60-85 wt %, even more preferably about 65-80 wt %, based on the total weight of the coating composition.

[0085] In the coating composition, the cosolvent may be an organic solvent commonly used in the art. For example, the cosolvent may be one or at least two of alkyl alcohol, alcohol ether, ketone or ester. Examples of co-solvents include, but are not limited to, ethanol, isopropanol, butanol, butoxydiglycol, butyl glycol, dipropylene glycol methyl ether (DPM), propylene glycol methyl ether, ethylene glycol butyl ether, dipropylene glycol butyl ether (DPnB), ethylene glycol ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, ethylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, ethylene dimethanol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monoisobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, ethylene glycol monomethyl ether acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, trimethylbenzene, 100# solvent naphtha, 2-methylpropanol acetate and n-butyl acetate, and any combination thereof.

[0086] Based on the total weight of the coating composition, the amount of the cosolvent may be about 4-10 wt %, preferably about 5-9 wt %, more preferably about 6-8 wt %. For example, based on the total weight of the coating composition, the amount of the cosolvent may be even more preferably about 6.5, 7, 7.5 or 8 wt %.

[0087] Preferably, the coating composition described herein. Based on the total weight of the coating composition, the amount of water can be about 5-40 weight %, preferably about 8-35 weight %, more preferably about 10-30 weight %. For example, based on the total weight of the coating composition, the amount of water can be about 12, 13, 14, 15, 16, 18, 20, 22 or 25 weight %.

[0088] The coating composition of the present invention can also optionally include other additives. Other additives can be those commonly used in coating compositions. These additives will not adversely affect the coating composition or the cured coating obtained therefrom. Suitable additives include, for example, those reagents that can improve the processing properties or manufacturing properties of the composition, enhance the aesthetics of the composition, or improve the specific functional properties or characteristics (such as adhesion to substrate) of the coating composition or the cured coating obtained therefrom. According to specific needs, the additives that can be included in the coating composition are, for example, but not limited to, pigments, fillers, anti-skinning agents, driers, emulsifiers, anti-migration aids, antibacterial agents, chain extenders, lubricants, wetting agents, biocides, plasticizers, defoamers, colorants, waxes, antioxidants, corrosion inhibitors, antifreeze agents, rheological aids, thickeners, dispersants, pH regulators, adhesion promoters, UV stabilizers, pH regulators, leveling agents or combinations thereof. The content of each optional component is enough to achieve its intended purpose, but preferably, such content will not adversely affect the coating composition or the cured coating obtained therefrom.

[0089] In some preferred embodiments, the pigment can be a spherical, fibrous, flaky or other regular or irregularly shaped material with a micron or even nanometer size. Examples of pigments include metal oxides such as titanium dioxide, iron oxide, zinc oxide, zirconium oxide, aluminum oxide; mixed metal oxides of two or more metals, the metals including manganese, nickel, titanium, chromium, antimony, magnesium, cobalt, iron or aluminum; oxymetallic compounds such as bismuth vanadate, cobalt aluminate, cobalt zincate, zinc chromate; pigments with metallic effects such as aluminum flakes, copper and copper / zinc alloys; pearlescent pigments such as lead carbonate and bismuth oxychloride; talc; and any combination thereof. Preferably, the pigment is titanium dioxide, more preferably titanium dioxide in powder form. Particularly preferably, the pigment comprises rutile titanium dioxide. All types of thickeners are commercially available commodities. For example, as an example of a pigment, BLR-688 titanium dioxide purchased from Baili Lian can be used.

[0090] Based on the total weight of the coating composition, the total amount of the pigment can be 0 wt % to 50 wt %, such as 1 wt % to 45 wt %, 2 wt % to 40 wt %, 3 wt % to 35 wt %, 4 wt % to 30 wt %, 5 wt % to 25 wt %, 10 wt % to 20 wt %. Further preferably, based on the total weight of the coating composition, the amount of each pigment is independently 0 wt % to 50 wt %, 1 wt % to 40 wt %, 2 wt % to 30 wt %, 3 wt % to 20 wt %, 4 wt % to 15 wt %.

[0091] Preferably, other additives include one or more of a defoamer, a leveling agent, a thickener and a wetting agent. As an example of a leveling agent, BYK 358 purchased from BYK can be used. As an example of a defoamer, BYK-071 purchased from BYK can be used.

[0092] In a preferred embodiment, the coating composition of the present invention comprises about 0 to about 30 wt %, preferably about 0.1 to about 25 wt %, of other additives, relative to the total weight of the coating composition. Specifically, the amount of each other additive in the coating composition is 0.1 wt % to 10.0 wt %, such as 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.6 wt %, 0.7 wt %, 0.8 wt %, 0.9 wt %, 1 wt %, 1.1 wt %, 1.2 wt %, 1.3 wt %, 1.4 wt %, 1.5 wt %, 1.8 wt %, 2.0 wt %, 2.5 wt %, 3.0 wt %, 3.5 wt %, 4.0 wt %, 4.5 wt %, 5.0 wt %, 6.0 wt %, 8.0 wt % or 9.0 wt %, relative to the total weight of the coating composition.

[0093] Suitable thickeners include one or more of cellulose thickeners, alkali swellable thickeners, polyurethane thickeners, hydrophobically modified polyurethane thickeners, and inorganic thickeners. All types of thickeners are commercially available commodities. For example, as an example of a cellulose thickener, methyl hydroxyethyl cellulose ether thickener HEC 250H4BR purchased from ASHLAND, USA, can be used. As an example of an alkali swellable thickener, ASE60 purchased from Dow Chemical DOW, USA, can be used. As an example of a polyurethane thickener, RM-2050D purchased from Dow Chemical DOW, USA, or U902 and U903 purchased from Wanhua Chemical can be used. As an example of an inorganic thickener, bentonite can be used.

[0094] In some embodiments, the coating composition of the present invention may include about 0.1 wt % to about 5.0 wt %, preferably about 0.5 wt % to about 4.0 wt %, more preferably 1.0 wt % to 3.0 wt % of thickener relative to the total weight of the coating composition. For example, the coating composition of the present invention includes 1.2 wt %, 1.5 wt %, 2.0 wt % or 2.5 wt % of thickener relative to the total weight of the coating composition.

[0095] The coating composition according to the present invention may optionally contain a defoamer. Suitable defoamers include one or more of organosiloxane defoamers, grease defoamers, polyether defoamers, and polyether-modified organosilicon defoamers. Preferably, nonionic mineral oils may be used. All types of defoamers are commercially available products. As an example of a defoamer, CF-246 purchased from Blackburn may be used.

[0096] In some embodiments, the coating composition of the present invention may include about 0 wt % to about 1.0 wt %, preferably about 0.3 wt % to about 0.5 wt % of a defoaming agent, relative to the total weight of the coating composition.

[0097] In some preferred embodiments, the coating composition comprises, based on the total weight of the coating composition:

[0098] 50-90 wt % of a film-forming resin;

[0099] 4-10 wt % of a cosolvent;

[0100] 5-40 wt % water; and

[0101] 0.3-5 wt% of a modified polycarbodiimide compound.

[0102] Further preferably, based on the total weight of the coating composition, the coating composition further comprises 0-1 wt % of other additives. The other additives may include one or more of a defoamer, a leveling agent, a thickener and a wetting agent.

[0103] In some embodiments, component B) may also include other crosslinking agents in addition to the modified polycarbodiimide compounds described herein. The inventors have found that the use of other crosslinking agents can stabilize the improvement in the resistance of the paint film and even further improve the resistance of the paint film.

[0104] In the coating compositions described herein, preferably, the other crosslinking agents may be free or substantially free of allergenic substances (eg, aziridine and the like).

[0105] The other crosslinking agent may include a compound having -N=C=N- or an epoxy functional group. In some embodiments, the other crosslinking agent includes a carbodiimide compound different from the modified polycarbodiimide compound described herein, a silane compound, or a combination thereof.

[0106] The above-mentioned carbodiimide compounds have at least one -N=C=N- structure. Preferably, the carbodiimide compounds have more than 2 carbodiimide groups or polycarbodiimide compounds of carbodiimide derivative structures in the molecule. More preferably, the carbodiimide compounds have more than 3 carbodiimide groups in the molecule. For example, in some exemplary embodiments, the carbodiimide compounds have 3 to 7 carbodiimide groups. The carbodiimide compounds may include aliphatic carbodiimide compounds, alicyclic carbodiimide compounds, and aromatic carbodiimide compounds.

[0107] Carbodiimide compounds are water-soluble or water-dispersible. In the absence of particular restrictions, any polycarbodiimide compound that can be stably dissolved or dispersed in an aqueous medium can be used as such a water-soluble or water-dispersible polycarbodiimide compound. Specific examples of water-soluble or water-dispersible polycarbodiimide compounds include CARBODILITE SV-02, CARBODILITE V-02, CARBODILITE V-02-L2, CARBODILITE V-04, CARBODILITE E-01, CARBODILITE E-02, and CARBODILITE E-05 (trade names, purchased from Nisshinbo Industires, Inc.) as polycarbodiimide compounds. The above polycarbodiimide compounds can be used alone or in combination of two or more.

[0108] Carbodiimide compounds can also be synthesized by generally known methods, for example, by decarboxylation condensation reaction of various polyisocyanates using an organic phosphorus compound or an organic metal compound as a catalyst at a temperature of about 70° C. or above in a solvent-free or inert solvent.

[0109] A silane compound may be used as a crosslinking agent. Preferably, the silane compound is an epoxy silane compound. The epoxy equivalent of the epoxy silane compound is in the range of 4 to 6 meq / g.

[0110] In some embodiments, the epoxysilane compound is an epoxysilane oligomer of formula (I):

[0111]

[0112] Wherein R and R1 are independently substituted or unsubstituted alkyl; R2 is independently substituted or unsubstituted linear, branched or cyclic alkyl or alkyl ether residue substituted by epoxide; R3 is hydrogen or substituted or unsubstituted alkyl, and x+y≥2, x≥0.

[0113] In formula (I), preferably, R and R1 are independently C 1-10 Alkyl (e.g., linear or branched), including aryl-substituted alkyl (i.e., arylalkyl). For example, R and R1 are independently methyl or ethyl. In some embodiments, R and R1 are independently substituted or unsubstituted arylalkyl having at least 7 carbon atoms, such as substituted or unsubstituted benzyl.

[0114] R2 is a substituted or unsubstituted straight chain, branched chain or cyclic alkyl group or an alkyl ether residue substituted by an epoxide having less than or equal to 30 carbon atoms.

[0115] R3 is hydrogen or a substituted or unsubstituted alkyl group (straight chain or branched chain, including a cycloalkyl group) or an unsubstituted arylalkyl group.

[0116] The sum of x and y is at least 3.

[0117] For example, useful epoxysilane compounds have the following structure:

[0118]

[0119] Where R is C 1-10 Alkyl (eg, linear or branched), including aryl-substituted alkyl (ie, arylalkyl). For example, R is independently methyl or ethyl.

[0120] Exemplary epoxy silane compounds include, for example, CoatOSil MP 200, which is commercially available.

[0121] The amount of the other crosslinking agent can be appropriately adjusted according to the type of the other crosslinking agent, the film-forming resin, and the desired properties of the paint film. Based on the total weight of the coating composition, the amount of the other crosslinking agent can be about 0.3 wt % to 8 wt %, preferably about 0.5 wt % to 6 wt %, and more preferably about 1 wt % to 5 wt %. For example, based on the total weight of the coating composition, the amount of the crosslinking agent can be about 1.2 wt %, about 2 wt %, about 3 wt %, or about 4 wt %.

[0122] The preparation of coating composition of the present invention can be realized by any suitable mixing method well known to those of ordinary skill in the art. For example, coating composition can be made by adding film-forming resin or emulsion, cosolvent, crosslinking agent and optional additives to a container, and then stirring the resulting mixture to uniformity. Or coating composition can be made by mixing crosslinking agent with cosolvent, and then adding film-forming resin or emulsion and optional additives, thereby forming a uniform mixture. Water can be added during the preparation of coating composition.

[0123] Aqueous coating composition of the present invention can be applied by conventional methods known to those of ordinary skill in the art. Preferably, the coating composition is applied by brushing, spraying and other coating methods known in the art. In this way, a coating can be formed by the coating composition of the present invention, and this coating also falls within the scope of protection of the present invention. Therefore, the present invention also provides the coating that can be obtained by the coating composition as herein described.

[0124] The coating composition described herein is suitable for use in applications such as wood, metal, plastic, interior wall, exterior wall, and cement board, etc. It is particularly suitable for use as a wood coating composition.

[0125] A third aspect of the present application provides a coated product comprising a substrate and the coating composition described herein coated on the substrate or a cured coating formed therefrom.

[0126] The substrate can be selected from one or more of wood, metal, plastic, interior wall, exterior wall and cement board. Examples of suitable substrates include wood, cement, cement fiberboard, wood-plastic composite, tile, metal, plastic, glass and fiberglass. Preferably, coating composition of the present invention is particularly suitable for use on wooden substrates. Suitable wooden substrates include substrates obtained from wooden materials, such as oak (for example white oak and red oak), pine (for example white pine and southern yellow pine), poplar, spruce, cherry, walnut, redwood, cedar, maple, mahogany, birch, hickory, walnut, ash, etc. Preferred wood for wooden substrates includes those woods that are color-developing and easy to UV light discoloration, such as oak, pine, maple, etc. In addition, wooden substrates can be engineered wood products, wherein the substrate is made of wood chips (for example sheets, fragments, flakes, fibers, silk strips).

[0127] Unless stated otherwise, the various features and corresponding preferences described herein may be combined.

[0128] Example

[0129] The disclosure of the present invention is described in more detail by the following examples. These examples are only for illustrative purposes. The embodiments of the present invention are not limited to these specific examples. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on weight. Moreover, all reagents used in the examples are commercially available and can be used directly without further treatment. For example, the PCDI raw material in the following examples is commercially available CARBODILITE E-05. Those skilled in the art can easily purchase or prepare the raw materials used in the examples.

[0130] Test Method

[0131] Chemical resistance (or liquid resistance): According to GB / T 4893.1, the resistance of the paint film to Na2CO3, acetic acid, water and hot water is measured with the corresponding test time. The results are evaluated using a grading standard, where 5 = best and 0 = worst.

[0132] Infrared spectroscopy (FT-IR): The samples were subjected to attenuated total reflectance (ATR) testing using an American Thermo Nicolet Nexus 470-FTIR infrared spectrometer.

[0133] Differential Scanning Calorimetry (DSC): The samples were tested using a TA DSC Q2000 differential scanning calorimeter with a set temperature range of -50°C to 150°C and a program heating rate of 20°C / min.

[0134] Example 1: Preparation and characterization of modified polycarbodiimide compounds

[0135] Benzotriazole was dissolved in dipropylene glycol methyl ether (DPM) and dipropylene glycol butyl ether (DPnB) according to the reagents and weight percentages described in Table 1. Then, it was added to commercially available CARBODILITE E-05 (solid content 40%) under stirring at room temperature. After the reaction, a modified polycarbodiimide compound (represented by PCDI#) was obtained. It includes PCDI#-A (modified with 1.5% benzotriazole), PCDI#-B (modified with 2% benzotriazole), PCDI#-C (modified with 4.5% benzotriazole) and PCDI#-D (modified with 6% benzotriazole).

[0136] As a control, no benzotriazole was added to the PCDI sample.

[0137] The weight percentages in Table 1 are based on the total weight (ie, 100 g) of each reagent (including DPM, DPnB, benzotriazole and PCDI).

[0138] Table 1. Preparation and characterization of PCDI#

[0139]

[0140] The control sample PCDI and the sample PCDI#-C were subjected to infrared analysis and DSC analysis respectively. The results are shown in Figure 1 and Figure 2-Figure 3 middle.

[0141] Figure 1 The infrared absorption spectra of PCDI and PCDI#-C are compared with the methyl peak as a reference. In the FT-IR graph, under the premise of consistent methyl peak intensity, PCDI#-C has a peak intensity of about 2130 cm -1 The N=C=N characteristic peak intensity at about 1660 cm-1 decreased, indicating that a part of the N=C=N group was reduced due to the reaction with benzotriazole. -1 There is an obvious peak enhancement at 740 cm -1 An obvious benzene ring skeleton stretching peak appeared at .

[0142] Figure 2 The DSC curve of benzotriazole is shown in Figure 1. It can be seen that benzotriazole has an obvious melting peak at about 99°C.

[0143] Figure 3 The DSC curves of PCDI and PCDI#-C are shown. Figure 3 It can be seen that the modified PCDI#-C does not have the melting peak of benzotriazole, and therefore does not contain residual benzotriazole compounds. Moreover, the Tg of PCDI#-C (13.84°C) is significantly higher than that of PCDI (4.84°C), and a new Tg (122.67°C) appears.

[0144] Combined with the infrared spectrum, it can be confirmed that in PCDI#-C, benzotriazole completely reacts with PCDI, and the modified PCDI#-C not only has the N=C=N structure with the same characteristic peaks as PCDI, but also has the characteristic peaks of the benzene ring in benzotriazole.

[0145] Example 2: Formulation of coating composition and coating properties

[0146] Commercially available emulsions or dispersions are used, as shown in Table 2. They include water-based acrylic emulsions (exemplified by Wanhua 4401), water-based self-crosslinking acrylic emulsions (exemplified by ROSHIELD TM3311), waterborne polyurethane modified acrylic emulsion (exemplified by E-129), waterborne polyurethane dispersion (exemplified by R-2180).

[0147] According to the components and amounts shown in Table 2, the components are mixed to obtain a coating composition. Wherein, based on the total weight of the emulsion or dispersion, the emulsion or dispersion contains 75 wt % of a film-forming resin, 3 wt % of DPM, 3.5 wt % of DPnB, 1.7 wt % of a defoamer, 0.3 wt % of a leveling agent, 0.6 wt % of a thickener, and 0.1 wt % of a rheological additive. The weight percentages in Table 2 are based on the total weight of the coating composition.

[0148] After the coating composition was applied on the wood, the sample was dried on the surface, baked at 40°C for 2 hours, and then dried at room temperature for 7 days. The properties of the obtained paint film were tested. The test results are shown in Table 2.

[0149] Table 2. Coating composition and film properties

[0150]

[0151]

[0152] It can be seen that the modified polycarbodiimide compound of the present invention can be applied to a variety of different emulsion or dispersion coating systems, and can improve the chemical resistance of the coating, especially significantly improve the water resistance.

[0153] In order to determine the high temperature stability of the modified polycarbodiimide compound, the PCDI#-C used in Example 2 was placed in a 50°C oven for one month (represented by PCDI#-C(1M)), and then PCDI#-C(1M) was compared in parallel with unmodified commercially available PCDI and PCDI#-C that had not been subjected to 50°C heat storage. Specifically, under the same conditions of other parameters, two-component coatings were prepared using PCDI#-C(1M), PCDI and PCDI#-C, respectively. After the coatings were applied to the wood, the samples were dried on the surface, baked at 40°C for 2 hours, and then dried at room temperature for one or seven days, and the water resistance of the paint film was tested. The water resistance test results are shown in Figure 2. Figure 4 shown.

[0154] exist Figure 4 In the figure, the first column shows the water resistance photos of the paint films prepared with unmodified commercial PCDI tested after drying for 1 day or 7 days; the second column shows the water resistance photos of the paint films prepared with benzotriazole-modified PCDI#-C; and the third column shows the water resistance photos of the paint films prepared with benzotriazole-modified PCDI#-C after a 1-month hot storage test.

[0155] from Figure 4The results show that although PCDI#-C (1M) was stored in a 50°C oven for one month, the paint film prepared by it still showed stable and excellent water resistance (the whitening of the paint film was equivalent to that of PCDI#-C). The paint film obtained by using unmodified commercial PCDI was obviously whitened after drying at room temperature for 1 day or 7 days. It can be seen that benzotriazole-modified PCDI# can still improve the water resistance of the paint film after a month of hot storage test, and thus has excellent thermal stability.

[0156] Example 3: Comparison of different cross-linking agents

[0157] In order to compare the properties of other crosslinking agents, CoatOSil MP 200 epoxy silane compound and DSM CX100 multifunctional aziridine were used as crosslinking agents. Considering that the solid content of MP200 and CX100 is 100%, the amount of 1.2% is used for comparison.

[0158] Table 3. Coating compositions and film properties using different crosslinkers

[0159]

[0160] As can be seen from Table 3, the chemical resistance obtained by using modified PCDI# is significantly better than that of PCDI, and is even comparable to the effect of epoxysilane compounds, and close to the effect of multifunctional aziridine. It can be seen that the crosslinking density and chemical resistance of the paint film obtained by using polycarbodiimide compounds can be greatly improved by simple modification.

[0161] Moreover, it is worth noting that the PCDI# of the present invention is non-allergenic, thus avoiding the allergenic defect of aziridine. The scheme of the present invention is simple, easy to implement, low in cost and safer.

[0162] Example 4: Effects of different modification degrees on paint film properties

[0163] By adding different amounts of benzotriazole, the -N=C=N- structural unit in the modified PCDI# is adjusted. The relative content of the structural unit. The obtained paint film was tested for chemical resistance. The results are shown in Table 4 below.

[0164] Table 4

[0165]

[0166]

[0167] As can be seen from Table 4, the use of PCDI#-B and PCDI#-C further optimized the chemical resistance of the paint film. The relative content of the structural units can be adjusted to control the degree of modification and further optimize the chemical resistance of the paint film.

[0168] Example 5: Effect of modified PCDI with different compounds on paint film properties

[0169] Modified PCDI modified by different compounds were prepared, and the "4.5%" of the crosslinking agent shown in Table 5 was based on the total weight of each reagent (including DPM, DPnB, modifier and PCDI) used to prepare the modified PCDI#. Then, the coating composition was prepared using the same method and amount as in Example 2 (using 3 wt% of the crosslinking agent based on the total weight of the coating composition).

[0170] The obtained paint films were tested for chemical resistance. The results are shown in Table 5 below.

[0171] Table 5

[0172]

[0173] The results show that benzotriazole, benzimidazole, 2-phenylimidazole and indole can improve the resistance of the paint film compared with unmodified PCDI. In particular, benzotriazole, benzimidazole and 2-phenylimidazole can significantly improve the water resistance and acid resistance of the paint film. In the results of Table 5, the paint film obtained by using PCDI#-C modified with benzotriazole exhibits the best chemical resistance.

[0174] Although the present invention is described with reference to a large number of embodiments and examples, it is easy for those skilled in the art to see that the present invention can be changed without departing from the principles disclosed in the foregoing description. For example, without departing from the principles disclosed in the foregoing description, a plurality of features or preferred modes described herein are combined, and the resulting technical solutions should be understood to belong to the contents recorded herein. Such changes are deemed to be included in the following claims, unless the claims explicitly indicate otherwise. Accordingly, the embodiments described in detail herein are merely exemplary and are not intended to limit the scope of the present invention, which is the full scope of the attached claims and any and all equivalents thereof.

Claims

1. A modified polycarbodiimide compound having a -N=C=N- structural unit and The polymer backbone of the structural unit, wherein the is a nitrogen heterocycle connected to the polymer main chain, the nitrogen heterocycle is fused or chemically linked to an optionally substituted or optionally nitrogen-containing benzene ring, and the -N=C=N- structural unit on the polymer main chain is The molar ratio of the structural units is in the range of 100:80 to 100:

10.

2. The modified polycarbodiimide compound according to claim 1, wherein The number average molecular weight of the modified polycarbodiimide compound is in the range of 1500 to 5000 g / mol.

3. The modified polycarbodiimide compound according to any one of claims 1 to 2, which is prepared by reacting a polycarbodiimide compound with an aza-condensed ring compound or an aromatic-substituted aza-heterocyclic compound, wherein: The nitrogen-fused ring compound or the aromatic-substituted nitrogen-heterocyclic compound has a ring containing an -NH- bond.

4. The modified polycarbodiimide compound according to claim 3, wherein The nitrogen-fused ring compound or the aromatic-substituted nitrogen-heterocyclic compound has a five-membered nitrogen-heterocyclic structure.

5. The modified polycarbodiimide compound according to claim 4, wherein The five-membered nitrogen heterocyclic ring is fused or chemically bonded to the benzene ring.

6. The modified polycarbodiimide compound according to claim 4, wherein The aza-fused ring compound comprises one or more of benzotriazole, benzimidazole, indole, purine and phthalimide.

7. The modified polycarbodiimide compound according to claim 4, wherein The aromatic-substituted nitrogen heterocyclic compound includes one or more of 2-phenylimidazole and 2-phenyl-4-methylimidazole.

8. A coating composition comprising: Component A), comprising a film-forming resin, a cosolvent and optionally additives; Component B) comprises a crosslinking agent, wherein the crosslinking agent comprises the modified polycarbodiimide compound according to any one of claims 1 to 7.

9. The coating composition according to claim 8, wherein the film-forming resin comprises any combination of one or more of self-crosslinking resins, polyurethanes, polyurethane acrylates, alkyd resins, acrylic resins, isocyanate resins, polyurethane acrylate-modified epoxy resins, unsaturated polyester resins, acrylic epoxy resins and nitro resins.

10. The coating composition according to claim 8, wherein The amount of the modified polycarbodiimide compound is 0.3 to 5 wt % based on the total weight of the coating composition.

11. The coating composition according to any one of claims 8 to 10, wherein Based on the total weight of the coating composition, the component A) comprises: 50-90 wt % of the film-forming resin; 4-10 wt % of the cosolvent; 5-40 wt % water; and 0-1 wt % of the additives, the additives comprising one or more of a defoamer, a leveling agent, a thickener and a wetting agent.

12. The coating composition according to any one of claims 8 to 10, wherein The cross-linking agent further comprises a polycarbodiimide compound different from the modified polycarbodiimide compound, a silane compound or a combination thereof.

13. A coated article comprising: A substrate comprising one or more of wood, metal, plastic, interior wall, exterior wall and cement board; and A cured coating formed from the coating composition according to any one of claims 8 to 12 applied on the substrate.

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