Clear coat coating material for plastic parts

Abstract

The present invention relates to a protic solvent-based two-component clear coat coating material comprising: one or more poly(meth)acrylate polyols A having a hydroxyl value in the range of 160 to 240 mg KOH / g and a mass-average molecular weight in the range of 1000 to 7000 g / mol; a masterbatch component comprising one or more catalysts C for crosslinking hydroxyl groups and free isocyanate groups; one or more curing agents B selected from the group consisting of diisocyanates and polyisocyanates; and one or more organic solvents, preferably aprotic solvents, which can be contained in the masterbatch component, the curing agent component, or both the masterbatch component and the curing agent component. The present invention further relates to a method for coating a substrate using the coating material, and a method for using the coating material for coating a substrate, particularly a vehicle body and its parts.

Description

[Technical Field]

[0001] The present invention relates to a solvent-based two-component clear coat coating material comprising one or more poly(meth)acrylate polyols and isocyanate-containing curing agents, and particularly suitable for coating polymer substrates. Furthermore, the present invention relates to a method for coating an uncoated or pre-coated substrate with such a coating material, and to such a coated substrate. Furthermore, the present invention relates to a method for using the coating material to coat an uncoated or pre-coated substrate, particularly in vehicle coatings, such as automotive coatings. [Background technology]

[0002] While plastic component coatings play a crucial role, particularly in the automotive industry, their applications are not limited to this sector. Such coatings, especially the outermost clear coat layer, are subject to high demands regarding mechanical properties such as hardness and wear resistance. Furthermore, optical appearance plays a significant role in this area of ​​the coating industry; providing customers with a perfect appearance for the coating is considered essential, in addition to ensuring high mechanical quality.

[0003] Therefore, applying a clear coat to plastic parts, especially automotive plastic parts, remains a challenge because it is necessary to achieve high film hardness immediately after curing while simultaneously achieving a good optical appearance.

[0004] If the film hardness immediately after curing is insufficient, a plurality of problems will occur in subsequent processes. Specifically, it becomes almost impossible to sand and polish such parts, and it also becomes impossible to package or ship such parts. This is because it is necessary to avoid damage to the coating that is not fully cured by sanding and polishing, and the packaging material remaining attached to the coated surface. If the film hardness only develops after a long curing time, sanding, polishing, and packaging need to be postponed and cannot be carried out until sufficient hardness is obtained. This delays the process and wastes time and resources.

[0005] Furthermore, if the film hardness is low, the chemical resistance to certain chemicals decreases.

[0006] US 2021 / 291224 A1 provides a storage-stable one-component aqueous basecoat composition comprising a melamine formaldehyde crosslinking agent and a resin having a group reactive with the melamine formaldehyde crosslinking agent under an acid catalyst. When the basecoat composition is cured wet-on-wet with a solvent-based clearcoat composition containing a polyisocyanate crosslinking agent, it can be cured at a temperature of 110°C or lower.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] Furthermore, an object of the present invention is to provide a clearcoat material that can be cured at a low temperature while achieving performance equivalent to or better than that of a standard clearcoat and maintaining good appearance, such as good leveling properties.

Means for Solving the Problems

[0009] The above object is achieved by providing a solvent-based two-component clearcoat coating material comprising: i.a. one or more poly(meth)acrylate polyols A having a hydroxyl value in the range of 160 to 240 mg KOH / g and a mass average molecular weight in the range of 1000 to 7000 g / mol; and ii.a. one or more catalysts C for crosslinking hydroxyl groups and free isocyanate groups as masterbatch components, and i.b. one or more curing agents B selected from the group consisting of diisocyanates and polyisocyanates as curing agent components, and one or more aprotic organic solvents that can be contained in the masterbatch component, the curing agent component, or both the masterbatch component and the curing agent component; and protic solvents in the masterbatch component in an amount of 0 to 10% by mass based on the total amount of the aprotic organic solvent and the protic solvent contained in the coating material The further subject of the present invention is achieved by providing a method for coating a substrate, comprising the following steps: Hereinafter, the above solvent-based two-component clearcoat material and its preferred embodiments described later are referred to as "the clearcoat coating material of the present invention" or simply "the coating material of the present invention".

[0010] i. providing a substrate that is not coated or has been pre-coated; ii. applying at least one of the clearcoat coating materials of the present invention to the substrate provided in step i that is not coated or has been pre-coated to form a clearcoat layer; and iii. curing the clearcoat layer The above is a method for coating a substrate.

[0011] ​Hereinafter, the coating method for the above substrate and the preferred embodiments thereof described later will be referred to as "the coating method of the present invention" or simply "the method of the present invention," respectively.

[0012] Another subject of the present invention is a coated substrate, comprising a cured clear coat layer as a topcoat layer, wherein the clear coat layer is formed from the clear coat coating material of the present invention, and the substrate is a metal substrate, a glass substrate, a ceramic substrate, or a polymer substrate.

[0013] A further subject of the present invention is a method of using the clear coat coating material of the present invention to coat uncoated or pre-coated polymer substrates, preferably vehicle bodies or parts thereof, such as automobile bodies, and more preferably polymer parts of automobile bodies, such as bumpers or mirror caps. [Modes for carrying out the invention]

[0014] Clear coat coating materials The clear coat coating material of the present invention is included in the definition of a "two-component coating composition" or "two-component coating material" as defined in the textbook "Roempp Lexikon Lacke und Druckfarben" (Thieme, 1998). This is a composition in which curing occurs by mixing a masterbatch component ("Stammlack" or "A-Pack") and a curing agent component ("Haerter" or "B-Pack") in a specific mixing ratio. These components themselves are not suitable for film formation or do not form a durable film, and therefore are not coating compositions.

[0015] The clear coat coating material of the present invention is preferably easy to cure at low temperatures, i.e., temperatures in the range of 40°C to 90°C, preferably in the range of 50°C to 85°C, and more preferably in the range of 60°C to 75°C.

[0016] Furthermore, the clear coat coating material of the present invention contains one or more aprotic organic solvents, i.e., aprotic solvents that are not proton donors and are therefore chemically inert to reaction with NCO groups.

[0017] Masterbatch ingredients In this specification, the term "(meth)acrylic" (e.g., "(meth)acrylic acid," "(meth)acrylate," etc.) encompasses both the terms "acrylic" and "methacrylic." Therefore, "(meth)acrylic acid" refers to acrylic acid and methylacrylic acid, and "(meth)acrylate" refers to acrylate and methacrylate. As is commonly used in this art, the term "(meth)acrylate" as used, for example, in alkyl (meth)acrylate, refers to (meth)acrylic acid esters. Thus, alkyl (meth)acrylate is an alkyl ester of (meth)acrylic acid.

[0018] Furthermore, while the term poly(meth)acrylate is used for polymers obtained from the polymerization of monomers having a (meth)acrylic group, such as alkyl or cycloalkyl (meth)acrylates and (meth)acrylic acid, this does not preclude the use of further polymerizable monomers, such as vinyl aromatic hydrocarbons, to produce poly(meth)acrylates.

[0019] Preferably, the poly(meth)acrylate polyol A used in the coating material of the present invention is obtained by polymerization of monomers having only one ethylenically unsaturated group, such as a (meth)acrylic group, a vinyl group, or an allyl group.

[0020] Poly(meth)acrylate polyol A The poly(meth)acrylate polyol A used in the clear coat coating material of the present invention is preferably a copolymer formed from a hydroxyl-functional (meth)acrylate and a non-hydroxyl-functional monomer. The non-hydroxyl-functional monomer is selected from non-hydroxyl-functional (meth)acrylate and vinyl aromatic monomers.

[0021] The poly(meth)acrylate polyol A used in the clear coat coating material of the present invention has, in addition to the essential hydroxyl value and mass-average molecular weight, a theoretical glass transition temperature (T) using the Flory-Fox formula described in the experimental section of the specification, preferably in the range of 50°C to 100°C, more preferably 55°C to 95°C, and most preferably 60°C to 90°C. g ) has.

[0022] When the theoretical glass transition temperature of poly(meth)acrylate polyol A exceeds 100°C, the clear coat coating material of the present invention tends to form an excessively brittle film, and when the theoretical glass transition temperature of poly(meth)acrylate polyol A is less than 50°C, the clear coat coating material of the present invention tends to form an excessively soft film with low chemical resistance.

[0023] T g Since it is calculated from the type and amount of monomers in poly(meth)acrylate polyol A, the selection of monomers is T g Determines that some monomer types are T g The impact on [the subject] is also disclosed below.

[0024] The hydroxy-functional (meth)acrylate, preferably hydroxyalkyl (meth)acrylate, is selected from C2-C8 hydroxyalkyl (meth)acrylate, more preferably from C2-C6 hydroxyalkyl (meth)acrylate, and most preferably from C2-C4 hydroxyalkyl (meth)acrylate.

[0025] The specific hydroxy-functional (meth)acrylates used are preferably hydroxyalkyl (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0026] Non-hydroxyfunctional (meth)acrylates, preferably alkyl (meth)acrylates, are selected from C1-C8 alkyl (meth)acrylates, more preferably C2-C8 alkyl (meth)acrylates, and even more preferably C3-C6 alkyl (meth)acrylates. Cycloalkyl (meth)acrylates are preferably C3-C 10 -Cycloalkyl (meth)acrylate, more preferably C4-C8 cycloalkyl (meth)acrylate, and most preferably C4-C6 cycloalkyl (meth)acrylate, are selected.

[0027] Specific examples of linear or branched alkyl (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, ethylhexyl (meth)acrylate, 3,3,5-trimethylhexyl (meth)acrylate, stearyl (meth)acrylate, and lauryl (meth)acrylate; examples of cycloalkyl (meth)acrylates include, for example, cyclopentyl (meth)acrylate, isobornyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0028] In general, when alkyl (meth)acrylates and cycloalkyl (meth)acrylates are used in the production of poly(meth)acrylate polyols, the theoretical glass transition temperature increases. Furthermore, in the alkyl (meth)acrylates used in the production of poly(meth)acrylate polyols according to the present invention, the theoretical glass transition temperature tends to increase as the number of carbon atoms in the alkyl group of the alkyl (meth)acrylate increases.

[0029] Other monomers that can be used to polymerize poly(meth)acrylate polyols include, for example, vinyl aromatic hydrocarbons, such as vinylitol, alpha-methylstyrene, or particularly preferably styrene; acrylic acid or methylacrylic acid amides or nitriles; vinyl esters or vinyl ethers; and (meth)acrylic acid. Increasing the amount of vinyl aromatic hydrocarbons usually increases the glass transition temperature of the poly(meth)acrylic polyol.

[0030] Poly(meth)acrylate polyol A, in its polymerized form, contains the following monomers: a) One or more (meth)acrylic acid esters selected from alkyl (meth)acrylates and cycloalkyl (meth)acrylates; b) One or more hydroxyalkyl (meth)acrylates; c) One or more vinyl aromatic monomers; and d) Optionally (meth)acrylic acid, preferably acrylic acid It contains.

[0031] More preferably, the poly(meth)acrylate polyol is polymerized in the following amounts of monomer a) 20-40% by mass, preferably 25-35% by mass, of one or more (meth)acrylic acid esters selected from alkyl (meth)acrylates and cycloalkyl (meth)acrylates; b) 40-60% by mass, preferably 45-55% by mass, of one or more hydroxyalkyl (meth)acrylates; c) 10-30% by mass, preferably 15-25% by mass, of one or more vinyl aromatic monomers; and d) 0-5% by mass, preferably 0.5-4% by mass of (meth)acrylic acid It contains, The mass percentage is based on the total amount of all monomers present in the polymerized form within the poly(meth)acrylate polyol.

[0032] The amount of hydroxyl-functionalized (meth)acrylate is within the above range, preferably selected so that the hydroxyl value of riol A is in the range of 160-240 mg KOH / g, more preferably in the range of 170-230 mg KOH / g, and most preferably in the range of 180-220 mg KOH / g. The hydroxyl value of the poly(meth)acrylate polyol is determined by the method described in detail in the experimental section of the specification.

[0033] When the hydroxyl value of poly(meth)acrylate polyol A exceeds 240 mg KOH / g, the clear coat coating material of the present invention tends to form a film with insufficient crosslinking and weak resistance. When the hydroxyl value of poly(meth)acrylate polyol A is less than 160 mg KOH / g, the clear coat coating material of the present invention tends to form a film with excessively low crosslinking.

[0034] The poly(meth)acrylate polyol used in the clear coat coating material of the present invention has a mass-average molecular weight M in the range of 1,000 to 7,000 g / mol, preferably 1,500 to 6,500 g / mol, more preferably 2,000 to 6,000 g / mol, even more preferably 2,500 to 5,500 g / mol, and most preferably 3,000 to 5,000 g / mol, as measured by gel permeation chromatography (GPC), as described in detail in the experimental section of the specification. W It holds.

[0035] The mass-average molecular weight M of poly(meth)acrylate polyol A W If the mass average molecular weight M of poly(meth)acrylate polyol A exceeds 7,000 g / mol, the clear coat coating material of the present invention tends to have insufficient leveling properties and a solid content that is too low. W When the concentration is less than 1,000 g / mol, the clear coat coating material of the present invention tends not to crosslink sufficiently densely.

[0036] Catalyst C The solvent-based two-component clear coat coating material of the present invention contains one or more catalysts that promote the crosslinking reaction between the hydroxyl groups in the poly(meth)acrylate polyol curing agent and the free isocyanate groups in the diisocyanate and / or polyisocyanate. The catalyst should promote an efficient crosslinking reaction, but an excessively fast reaction rate should be avoided. In particular, if the efficiency is excessively high at very low temperatures, it will result in a poor appearance of the coating layer, especially poor leveling properties.

[0037] Particularly suitable catalysts are selected from the group consisting of tertiary amines and inorganic or organometallic catalysts.

[0038] Examples of tertiary amine catalysts include, for example, 1,4-diazabicyclo[2.2.2]octane (DABCO), triethylamine, and diisopropylethylamine. Examples of inorganic metal-containing catalysts include, for example, zinc oxide, bismuth oxide, and tin oxide.

[0039] However, more preferred are catalysts belonging to the group of zinc and bismuth salts containing organometallic catalysts, such as dioctyltin dilaurate (DOTL), dibutylthiodilaure (DBTL), and more preferably linear or branched, preferably branched, monocarboxylic acids (monocarboxylic acids with 4 to 14 carbon atoms, preferably 6 to 12, most preferably 8 to 10). Of the above, zinc salts are most preferred. Examples of such zinc and bismuth salts include zinc neodecanoate, zinc 2-ethylhexanoate, bismuth neodecanoate, and bismuth 2-ethylhexanoate.

[0040] Hardening agent components Hardener B The curing agent used in the curing agent component of the two-component clear coat coating material of the present invention is selected from diisocyanates and / or polyisocyanates and mixtures thereof.

[0041] By definition, diisocyanates must contain two isocyanate groups per molecule; that is, they must contain two free, or unblocked, NCO groups within the molecule. Polyisocyanates must contain, on average, more than two free isocyanate groups.

[0042] Suitable diisocyanates include, for example, substituted or unsubstituted aromatic, aliphatic, alicyclic, and / or heterocyclic diisocyanates.

[0043] Examples of preferred aromatic diisocyanates include: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane 4,4'-diisocyanate, diphenylmethane 2,4'-diisocyanate, p-phenylenediisocyanate, biphenyl diisocyanate, 3,3'-dimethyl-4,4'-diphenylenediisocyanate, and mixtures thereof.

[0044] Further preferred examples of aliphatic and alicyclic diisocyanates include tetramethylene 1,4-diisocyanate, hexamethylene 1,6-diisocyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, isophorone diisocyanate, ethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, methylcyclohexyl diisocyanate, hexahydrotoluene 2,4-diisocyanate, hexahydrotoluene 2,6-diisocyanate, hexahydrophenylene 1,3-diisocyanate, hexahydrophenylene 1,4-diisocyanate, perhydrodiphenylmethane 2,4'-diisocyanate, 4,4'-methylenedicyclohexyl diisocyanate (e.g., Bayer Examples include AG's Desmodur® W), tetramethylxyl diisocyanate (e.g., American Cyanamid's TMXDI®), and mixtures of the above diisocyanates.

[0045] Among the above diisocyanates, aliphatic and / or alicyclic diisocyanates are most preferred. Preferred examples include, for example, hexamethylene 1,6 - diisocyanate, isophorone diisocyanate, and 4,4'-methylenedicyclohexyl diisocyanate. Further, preferred diisocyanates are biuret dimers and uretdione dimers of the above diisocyanates.

[0046] Particularly suitable polyisocyanates are trimers of diisocyanates, particularly trimers of the above diisocyanates. The most preferred trimers of diisocyanates are isocyanurate trimers and iminooxadiazidione trimers, among which isocyanurate trimers are more preferred. Most preferred are isocyanurate trimers of aliphatic and / or alicyclic diisocyanates, such as isocyanurate trimers of hexamethylene 1,6 - diisocyanate, isophorone diisocyanate and / or 4,4'-methylenedicyclohexyl diisocyanate.

[0047] The diisocyanates and / or polyisocyanates used in the present invention can be dissolved in one or more aprotic organic solvents and used. Preferred aprotic organic solvents shall be those described respectively below. Particularly preferred are hydrocarbons such as solvent naphtha and esters such as butyl acetate. However, it should be avoided to introduce water and / or protic solvents into the curing agent component. This is to avoid premature reactions between free NCO groups and these solvents.

[0048] Solvent S Aprotic organic solvent S a Examples of aprotic solvents used in the present invention include, for example, aliphatic and / or aromatic hydrocarbons, such as toluene, xylene, solvent naphtha, Solvesso 100 or Hydrosol® (available from ARAL), parachlorobenzotrifluoride; ketones, such as acetone, methyl ethyl ketone, methyl propyl ketone or methyl amyl ketone; esters, such as ethyl acetate, butyl acetate, pentyl acetate, methoxypropyl acetate or ethyl ethoxypropionate; ethers; or mixtures of the above solvents.

[0049] Among aprotic organic solvents, it is preferable to use at least some polar aprotic solvents to obtain high conductivity. Examples of such polar aprotic solvents include ketones, such as acetone, methyl ethyl ketone, methyl propyl ketone, or methyl amyl ketone; esters, such as ethyl acetate, butyl acetate, pentyl acetate, methoxypropyl acetate, or ethyl ethoxypropionate; ethers; or mixtures of the above polar aprotic solvents.

[0050] Therefore, it is preferable that one or more aprotic organic solvents used in the coating material of the present invention be selected from polar aprotic solvents, mixtures of polar aprotic solvents, or mixtures of polar aprotic solvents and one or more nonpolar aprotic solvents, such as aliphatic and / or aromatic hydrocarbons.

[0051] Aprotic organic solvents can be used in masterbatch components, curing agent components, or both.

[0052] Protic organic solvent S p In the clear coat coating material of the present invention, it is preferable that no protic organic solvent is contained, i.e., that it contains 0% by mass. If such a protic organic solvent is included, for example, alcohol, glycol, glycol ether, and glycolic acid ester, it is preferably contained in an amount of 0 to 10% by mass, more preferably 0 to 5% by mass, and most preferably 0 to 3% by mass, based on the total amount of the aprotic organic solvent and the protic organic solvent.

[0053] If present, protic organic solvents are used in the masterbatch components to avoid premature reactions with the curing agent.

[0054] water Water, as an inorganic protic solvent, reacts with isocyanates, forming carbon dioxide in the reaction, which can degrade the surface properties of the clear coat layer. Therefore, water should not be included in the two-component coating material of the present invention. Accordingly, water should not be intentionally added to the clear coat coating material of the present invention. However, the organic solvent or solvent mixture preferably contains a trace amount of water, with a water content of preferably 0.5% by mass or less, more preferably 0.2% by mass or less, based on the organic solvent or organic solvent mixture. Most preferably, the organic solvent or mixture thereof does not contain water.

[0055] Further ingredient F Further component F may be included in the masterbatch component, the curing agent component, or both. However, since the curing agent component includes an isocyanate-containing curing agent that reacts with many compounds, it is preferable that further component F be used in the masterbatch component.

[0056] Unmodified metal oxides and metalloids (F o ) The masterbatch components preferably contain at least one unorganically modified metal oxide and / or metalloid oxide. "Unorganically modified" means that the metal oxide and / or metalloid oxide have not undergone typical modifications, such as those by organosilanes, which result in hydrophobic surface modification.

[0057] Examples of such metal oxides include aluminum oxide and zirconium oxide, while a preferred example of a metalloid oxide is silica, with precipitated silica or fumed silica being particularly preferred, and most preferably fumed silica, with a BET surface area of ​​250-500 m². 2 / g, preferably 300-450m 2 / g, most preferably 350-450m 2 This is fumed silica in the range of / g.

[0058] Such metal oxides and metalloid oxides generally have hydroxyl groups on their surface and are therefore usually chemically modified, particularly hydrophobically. However, the inventors of the present invention found that such hydrophobically modified metal oxides and / or metalloid oxides are unsuitable for improving chemical resistance in the present invention. Only those that are not organically modified improved the chemical resistance of the clear coat layer formed from the clear coat coating material of the present invention.

[0059] Unmodified metal oxides and / or metalloids are used in the two-component clear coat coating material of the present invention, as described above, with a polymer binder and one or more aprotic organic solvents S. a It is preferably used in the form of a paste containing the polymer binder. The polymer binder is the poly(meth)acrylate polyol A defined above or one or more further polymer binders F described below. a That is the case.

[0060] It is preferable that one or more metal oxides and / or metalloids are included in the masterbatch components.

[0061] Further polymer binder (F b ) The solvent-based two-component clear coat coating material of the present invention may contain further polymer binders other than poly(meth)acrylate polyol A. The term "binder" refers to the non-volatile portion (solids) of a coating material that does not contain pigments or fillers, in accordance with EN ISO 4618:10-2006.

[0062] If present, such further polymer binders are preferably poly(meth)acrylate polyols, provided they have a hydroxyl value and / or mass-average molecular weight outside the range of essential poly(meth)acrylate polyol A.

[0063] However, the additional polymer binder is selected from the group of polyesters, polyethers, or polyurethanes. However, if included, it is most preferably selected from the group of poly(meth)acrylates, particularly poly(meth)acrylate polyols.

[0064] Such further polymer binders may be part of a paste containing the organically unmodified metal oxides and / or metalloids described above, or they may be part of a sagging control agent, for example, described below.

[0065] Preferably, a further polymer binder is included in the masterbatch components.

[0066] Sagging control agent (F SCA ) The sagging control agent (SCA) preferably used in the solvent-based two-component clear coat coating material of the present invention preferably further comprises a resin and urea crystals bonded to one or more aprotic organic solvents.

[0067] Typically, urea crystals suitable for use herein are reaction products of one or more amines and one or more diisocyanates and / or polyisocyanates.

[0068] The amine is selected from primary amines, secondary amines, diamines, ketamines, aldimines, or combinations thereof. The amine is preferably an amine monomer. Most preferably, the amine is a primary amine, and more preferably a primary monoamine.

[0069] Examples of primary amines include benzylamine, ethylamine, isopropylamine, n-propylamine, 1-butylamine, 2-butylamine, t-butylamine, n-pentylamine, 2-methyl-1-butylamine, 1-hexylamine, 2-hexylamine, 3-hexylamine, octylamine, decylamine, laurylamine, stearylamine, cyclohexylamine, and aniline. Other suitable primary amines include alkyl etheramines, such as 2-aminoethanol alkyl ether, 3-aminopropanol alkyl ether, and 2-aminopropanol alkyl ether.

[0070] Examples of secondary amines include, for example, N-alkyl derivatives of any of the primary amines mentioned above, where alkyl means an alkyl radical having 1 to 10 carbon atoms.

[0071] Examples of diamines include aliphatic and alicyclic diamines, such as ethylenediamine, 1,2-propylenediamine, 1,3-diaminopropane, 1,4-butanediamine, neopentanediamine, 4,4-diaminodicyclohexylmethane, isophoronediamine, hexamethylenediamine, 1,12-dodecanediamine, piperazine, polyetherdiamine, polytrimethyleneetherdiamine, or combinations thereof.

[0072] Any combination of the amines listed above is also suitable.

[0073] Preferably, the amine is selected from the group consisting of benzylamine, ethylamine, n-propylamine, 2-propylamine, n-butylamine, 2-butylamine, t-butylamine, n-pentylamine, α-methylbutylamine, α-ethylpropylamine, β-ethylbutylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, aniline, and combinations thereof. The most preferred amine is benzylamine.

[0074] The diisocyanate and / or polyisocyanate used in the production of urea crystals for the sagging control agent is preferably selected from those already disclosed as curing agent B included in the curing agent component.

[0075] Therefore, it is preferable to use the diisocyanates and polyisocyanates described in the section on curing agent components. Particularly preferred are the diisocyanates described herein, and even more preferred are the aliphatic diisocyanates described herein. Most preferred is 1,6-hexamethylene diisocyanate.

[0076] Particularly preferred are sagging control agents containing urea crystals, the urea crystals being made from benzylamine and 1,6-hexamethylene diisocyanate.

[0077] The sagging control agent (SCA) containing urea crystals preferably contains a further resin as a modifying resin which is preferably present during the reaction of the isocyanate and amine. This resin is preferably selected from poly(meth)acrylic polymers and polyester resins, most preferably poly(meth)acrylic polyols and hydroxy-functional polyester resins. The resin may contain a further polymer binder F b You can also choose from the following: If urea formation occurs in the presence of a hydroxy-functionalized resin, some of the formed urea may not only physically bond with the resin, but also be partially chemically bonded through urethane formation as a side reaction between the hydroxyl groups of the resin and the isocyanate groups of the diisocyanate.

[0078] The formation of urea crystals is preferably carried out in the presence of such further resin and one or more aprotic organic solvents. The aprotic organic solvent is aprotic organic solvent S a It is selected from those disclosed above.

[0079] The sagging control agent is preferably used in the masterbatch component.

[0080] (Further) coating additives (F a ) The coating additives described below include poly(meth)acrylate polyol A, catalyst C, curing agent B, aprotic or protic solvent, the above metal oxides and metalloid oxides, and the above further polymer binder F. b and sagging control agent F SCA It is different.

[0081] Examples of suitable coating additives include, for example, UV absorbers such as 2-(2-hydroxyphenyl)benzotriazole, 2-hydroxybenzophenone, hydroxyphenyl-s-triazine, and oxanalides; light stabilizers known as HALS compounds ("hindered amine light stabilizers"; derivatives of 2,2,6,6-tetramethylpiperidine; for example, commercially available from BASF SE as Tinuvin® 292); benzotriazoles such as hydroxyphenylalkylbenzotriazole, or oxanalides; radical scavengers; slip additives; polymerization inhibitors; defoamers; wetting and dispersing agents such as silk oan, fluorine-containing compounds, carboxylic acid monoesters, phosphate esters; adhesion promoters; flow regulators; film-forming aids such as cellulose derivatives; rheology-controlling additives other than SCAs; and flame retardants.

[0082] Further coating additive F a It is preferably included in the masterbatch components.

[0083] amount Based on the solid content obtained by subtracting the solid content of coating agent B from the total solid content of the coating material, the following ranges of solid content are preferably applied to the components: One or more poly(meth)acrylate polyols A: 65-90% by mass, more preferably 70-85% by mass, most preferably 72-82% by mass; One or more catalysts C: 0.05 to 1% by mass, more preferably 0.1 to 0.75% by mass, most preferably 0.15 to 0.5% by mass; One or more unmodified metal oxides and / or metalloids: 0-5% by mass, more preferably 0.2-3% by mass, most preferably 0.3-2% by mass; One or more further polymer binders F, used as is, as part of a paste containing one or more metal oxides and / or metalloids, as part of a sagging control agent, or as part of other components. b : 0-30% by mass, more preferably 5-25% by mass, most preferably 10-20% by mass; Sagging control agent F SCA One or more urea crystals as part of (the amount of urea crystals is calculated from the total amount of amines and isocyanates used in the preparation for the formation of urea crystals): 0-5% by mass, more preferably 0.2-3% by mass, most preferably 0.5-1.5% by mass; and One or more (additional) coating additives F a : 0-10% by mass, more preferably 2-8% by mass, most preferably 3-7% by mass.

[0084] The above content figures are independent of whether the ingredient is used as a masterbatch component or a curing agent component.

[0085] The solid content of the curing agent component is preferably 50 to 100% by mass, more preferably 55 to 95% by mass. Most preferably, the solid content of the curing agent component is equal to the solid content of one or more curing agents B in the curing agent component. However, the solid content may be low or high, and it is preferable to adjust the viscosity of the curing agent composition to the same range as the masterbatch composition in order to facilitate mixing of the curing agent composition and the masterbatch composition.

[0086] The solid content of the coating material, masterbatch components, curing agent components, and other components of the present invention was measured by the method described in the experimental section of the instructions.

[0087] Mixing ratio To produce a usable two-component clear coat composition, a masterbatch component containing poly(meth)acrylate polyol A is mixed with a curing agent component containing diisocyanates (one or more) and / or polyisocyanates (one or more).

[0088] The mixing ratio depends on the hydroxyl group content in the masterbatch components and the isocyanate group content of diisocyanates (single or multiple) and / or polyisocyanates (single or multiple) in the curing agent components.

[0089] In particular, considering interlayer adhesion, the clear coat material generally has a molar ratio of OH to NCO of 1:0.9 to 1:2, more preferably 1:0.9 to 1:1.5, and most preferably 1:1 to 1:1.2.

[0090] Method for coating substrates In the most common embodiment of the present invention, a method for coating a substrate includes the following steps: i. A process of providing an uncoated or pre-coated substrate; ii. A step of applying at least one clear coat coating material of the present invention to an uncoated or pre-coated substrate provided in step i to form a clear coat layer; and iii. A step of curing the clear coat layer at a temperature preferably in the range of 40°C to 90°C.

[0091] Base material The substrate used in the present invention is either uncoated or pre-coated, and is selected from metal substrates, glass substrates, and ceramic substrates, with polymer substrates (hereinafter also referred to as plastic substrates) being most preferred.

[0092] Polymer base Examples of polymer substrates coated by the method of the present invention include common polymer substrates such as polystyrene (PS), polyvinyl chloride (PVC), polyurethane (PUR), glass fiber reinforced unsaturated polyester, polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS), polyoxymethylene (POM), polyphenylene ether (PPE), polyphenylene oxide (PPO), polyurea, polybutadiene terephthalate (PBT), polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), polyolefins such as polypropylene (PP), and polypropylene (PP) modified with ethylene-propylene-diene copolymer (EPDM). In this context, polymer substrates containing various of the polymers listed above, i.e., mixtures of these polymers, can also be used. Naturally, the polymer substrate may contain fillers, may be a reinforced polymer substrate, or may be in the form of a composite material.

[0093] The polymer substrate may be a simple plastic sheet. More preferably, the substrate may include plastic vehicle bodies, specific vehicle parts, vehicle accessory parts, and vehicle parts installed inside or outside a vehicle. In this context, "vehicle" refers to all types of vehicles, including aircraft and ships, but is particularly limited to automobiles.

[0094] Prior to application of the clear coat coating material of the present invention, the polymer substrate to be coated may undergo pretreatment and / or pre-coating. Examples of such pretreatments include cleaning with an organic solvent, UV irradiation of the substrate surface, sputtering, heat treatment, corona treatment, or flame treatment.

[0095] Other substrates Other substrates include, for example, metal substrates such as bare steel, cold-rolled steel, hot-dip galvanized steel, electro-galvanized steel, aluminum, zinc, magnesium, and the alloys mentioned above. The metal substrate may be pre-coated with one or more chemical conversion coating layers, electrodeposition coating layers, one or more primer coating layers, and one or more base coat layers, usually in the order described above.

[0096] Although undesirable, the use of a glass or ceramic substrate is possible.

[0097] Application of clear coat coating materials The application of the coating composition to a substrate, preferably a polymer substrate that has been pre-treated and / or pre-coated as described above, can be carried out by any conventionally known application technique, such as spraying, knife coating, coating, pouring, dipping, impregnation, dropping, or roll coating. Preferably, it is carried out by spray application. In such applications, the polymer substrate to be coated may remain stationary while the application apparatus or unit moves. Alternatively, the substrate to be coated may move while the application unit remains stationary or moves in an appropriate manner relative to the substrate. Examples of spray application methods include compressed air spraying (pneumatic coating), airless spraying, high-speed rotation, and electrostatic spray application (ESTA), which may be used in combination with hot spray application, such as hot air spraying, as needed.

[0098] The clear coat coating material is preferably applied with a conventionally known film thickness, for example, a wet film thickness of 10 μm to 200 μm, preferably 50 μm to 150 μm. The dry film thickness obtained after curing is preferably in the range of 5 μm to 60 μm, more preferably in the range of 10 μm to 50 μm, and most preferably in the range of 15 μm to 40 μm.

[0099] When a clear coat composition material is applied to a pre-coated substrate, the coating layer of the pre-coated substrate is preferably fully cured or at least partially cured, especially if the substrate is a polymer substrate.

[0100] However, it is possible that at least one of the coating layers of a pre-coated substrate has not completely cured. In that case, the clear coat layer is cured simultaneously with the uncured (completely) cured coating layer to which the clear coat coating material of the present invention is applied.

[0101] hardening After applying the clear coat coating material of the present invention, before curing, at least a portion of the solvent contained in the coating is evaporated at room temperature (23°C) or a slightly higher temperature, preferably 40°C or lower (flash off).

[0102] The clear coat coating material applied to the substrate, preferably a polymer substrate, is cured to form a clear coat layer. The curing of the applied clear coat coating material is not particularly noteworthy in terms of method and is carried out according to conventionally known general techniques, such as heating in a forced-air oven or irradiation with an infrared lamp.

[0103] Curing may be carried out at room temperature (23°C) or other temperatures, preferably at a high temperature in the range of 40°C to 90°C, preferably 50°C to 85°C, more preferably 55°C to 80°C, and most preferably 60°C to 75°C. The duration of the curing stage is also selected individually and depends on factors such as the type of substrate. For example, in the case of coating a polymer substrate, the softening temperature of the substrate must be taken into consideration, and for example, at low temperatures, the curing period needs to be longer. Curing is preferably carried out over a period of 5 to 120 minutes, more preferably 10 to 40 minutes. As described above, a flushing or pre-drying stage may also be carried out beforehand at room temperature or a slightly higher temperature for a period of 1 to 60 minutes. The curing conditions applicable to a particular substrate are part of general technical knowledge, and therefore, those skilled in the art can adjust and select the conditions as appropriate.

[0104] Coated substrate A further subject of the present invention is a coated substrate, which is untreated or pretreated and / or uncoated or pre-coated, and comprises a cured clear coat layer as a topcoat layer, which is formed from the coating material of the present invention.

[0105] The pretreatment and / or pre-coating of the substrate, and the substrate itself, are preferably the same as those described above in the method of the present invention.

[0106] Preferably, the coated substrate of the present invention is obtained by the method of the present invention.

[0107] How to use Another subject of the present invention is a method of using the solvent-based two-component clear coat coating material of the present invention for coating an uncoated or pre-coated substrate, preferably a polymer substrate, preferably a vehicle body or a part thereof.

[0108] The present invention will be described in further detail below with reference to comparative examples and examples of the invention. [Examples]

[0109] The following describes the clear coat of the present invention, a comparative clear coat, and the test methods used to evaluate the clear coat material and its components.

[0110] Test method Coating characteristics Packmark resistance (PMR) This test evaluated the pack mark resistance of clear coats for plastic materials. The purpose of this test was to evaluate, in the laboratory, the time-dependent surface sensitivity of coated plastic substrates or additional components to indentations caused by packaging materials used in customer sites, such as textiles, tissue paper, packaging wipes, and packaging bags.

[0111] The test panels were coated according to the method described in the examples and cured at 60°C, 70°C, and 80°C for 30 minutes, respectively. The test panels were then immediately placed in a standard climate chamber (23°C / 50% relative humidity) and each test point was marked. After a waiting period of 10-15 minutes, the first sample piece of the textile material was placed on the first test point, and a circular metal test load (500g, 5cm diameter, 3cm height) was applied to measure the PMR value at "0 hours". After removal from the oven, additional samples of each packaging material were placed on the marked areas of the test panel after aging periods of 1 hour, 3 hours, 6 hours, and 24 hours, and further test loads were applied. The loading points (positions where the test mass was placed) were marked with a pencil on the metal plate around each point. In each case, the test load and the sample of packaging material were removed 24 hours after the start of the individual load test.

[0112] After removing the final test medium, a visual evaluation of surface defects was performed. For this purpose, surface defects were illuminated with a bright light source, and the damage patterns were visually assessed. The evaluation was carried out according to Table 1 of DIN EN ISO 4628-1. Surface defects were evaluated on a scale from 0 to 5, where 0 represents no packaging marks at all, and 5 represents a clearly visible deep indentation on the surface. Other values ​​were visually ranked between these two extremes.

[0113] Sanding & Polishing Test The panels were prepared and cured according to the following work example, and then stored for 1 hour after curing. Subsequently, all samples were sanded in two areas using an automated, standardized robotic sanding machine and conventional sanding paper. After sanding, one area was automatically polished for 4 seconds using a state-of-the-art sponge and polishing paste. The other area was polished in the same manner, but for 10 seconds. After these polishing steps, the remaining polishing marks were visually evaluated on a scale from 1 to 5, where 1 = no polishing marks visible, 5 = polishing marks still clearly visible with only slight improvement from polishing, and other values ​​were visually ranked between these two extremes.

[0114] Chemical resistance (gradient oven test) Test panels were prepared according to the method described in the examples and cured at 80°C for 30 minutes. Chemical resistance was tested according to DIN EN ISO 2812-5 (December 2018) using a 1% by mass aqueous sulfuric acid solution, a 10% by mass aqueous hydrochloric acid solution, a 5% by mass aqueous sodium hydroxide solution, a 50% solution of artificial tree resin (corophony (CAS 8050-09-7, 94114-23-5) dissolved in pine oil (CAS 2228-95-7)), and deionized water. The test temperature was 36-78°C and the test time was 30 minutes. The lowest temperature at which damage to the clear coat was observed was recorded.

[0115] Chemical resistance (absorption medium / droplet method) In all tests, the test panels were prepared according to the examples and cured at 80°C for 30 minutes.

[0116] The FAM test solution according to DIN 51604-2:2020-02 was applied to the clear coat at room temperature (23°C) for 10 minutes according to DIN EN ISO 2812-3:2012-10. Unleaded gasoline according to DIN EN 228:2017-08 was applied to the clear coat at room temperature (23°C) for 10 minutes according to DIN EN ISO 2812-3:2012-12. Tree sap was applied to the clear coat at 45°C for 30 minutes according to DIN EN ISO 2812-4:2007-05 (Appendix A 4.1; Method A). Deionized water was applied to the clear coat at 80°C for 60 minutes according to DIN EN ISO 2812-4:2007-05 (Method A).

[0117] Before evaluation, the coated panel was stored at room temperature (23°C) for 1 hour. If any changes were observed visually, it was stored at 60°C (reflow conditions) for 2 hours. The final evaluation value (note) is the value after 1 hour at room temperature. If this value is not 0, an additional reflow treatment is performed at 60°C for 2 hours. Furthermore, the panel / damaged area is evaluated after this additional reflow, and this is considered the final result.

[0118] The evaluation conforms to DIN EN ISO 4628-1: 2016-07: Rating 0 - No change, meaning no perceptible change. Rating 1 - Very minor, i.e., slightly perceptible change Rating 2 - Minor, i.e., clearly perceptible change Rating 3 - Moderate, i.e., a very clearly perceptible change. Rating 4 - Significant, i.e., remarkable change Rating 5 - A very significant change.

[0119] Coating materials and their component properties Solids The solid content of the coating material, masterbatch components, curing agent components, and other components of the present invention was determined by drying approximately 1 g of each sample at 130°C for 60 minutes.

[0120] Hydroxyl value The hydroxyl value represents the amount (mg) of potassium hydroxide equivalent to the amount of acetic acid bonded to 1 g of polymer polyol, preferably acetylated poly(meth)acrylate polyol, by acetylation. For measurement, the sample was boiled with pyridine acetate anhydride, and the resulting acid was titrated with potassium hydroxide solution (DIN EN ISO 4629-2:2016-12).

[0121] Mass average molecular weight M W The poly(meth)acrylate polyols were measured by gel permeation chromatography (GPC) in each case, and their mass-average molecular weight M was in the range of 1,000 to 20,000 g / mol, particularly 1,500 to 10,000 g / mol. W To measure the molecular weight of a polymer by GPC, the completely dissolved molecules of the polymer sample are fractionated using a porous column stationary phase. A 0.1 mol / l acetic acid solution in tetrahydrofuran (THF) is used as the eluent. The stationary phase is a combination of Waters Styragel HR5, HR4, HR3, and HR2 columns. 5 mg of the sample is added to 1.5 mL of eluent and filtered through a 0.5 μm filter. After filtration, 100 μl of the polymer sample solution is injected into the column at a flow rate of 1.0 mL / min. Separation proceeds according to the size of the polymer coil formed in the eluent. Small molecules migrate more slowly than large molecules because they frequently diffuse into the pores of the column material. Therefore, large molecules are eluted faster than small molecules. Molecular weight distribution of polymer sample, number-average molecular weight M n , mass average molecular weight M W , and polydispersity M W / M n teeth 、The calculation is performed using chromatography software based on calibration curves created with the EasyValid validation kit, which contains unbranched polystyrene standards of various molecular weights available from Polymer Standards Service.

[0122] Theoretical glass transition temperature (Flory-Fox equation) Theoretical glass transition temperature (T) of poly(meth)acrylate polyols g The T of the copolymer was calculated. g The value is calculated using the Flory-Fox formula, and the T value of the homopolymer of the comonomers contained therein is calculated. g Calculate from the value. T of homopolymer g The values ​​can be obtained from the Polymer Handbook, 3rd edition, J. Brandup, IHImmergut, Chapter VI, pp. 215-225. The Flory-Fox formula is as follows: the mass fraction of each comonomer and the T of the corresponding homopolymer. g It is based on i

[0123]

number

[0124]

number

[0125]

number

[0126] Examples Unless otherwise specified, percentage values ​​are mass percentages, and parts are parts by mass (pbw).

[0127] Preparation of comparative clear coat material C1 and clear coat materials I1 and I2 of the present invention Masterbatch ingredients Hydroxyl-functionalized poly(meth)acrylate A used in Examples I1 and I2 of the present invention I A mixture of ethylenically unsaturated monomers consisting of 12 lbw butyl methacrylate, 18 lbw cyclohexyl methacrylate, 1 lbw acrylic acid, 22 lbw hydroxyethyl methyl acrylate, 27 lbw hydroxypropyl methyl acrylate, and 20 lbw styrene was polymerized in 67.5 lbw ethyl ethoxypropionate in the presence of 3.5 lbw di-tert-butyl peroxide.

[0128] The resulting polymer A has a hydroxyl value of 200 mg KOH / g, a mass-average molecular weight of 4150 g / mol, and a theoretical glass transition temperature of 69°C.

[0129] Hydroxyfunctional poly(meth)acrylate A used in Comparative Example C1 C1 Polymerization products of methyl methacrylate, hydroxyethyl methacrylate, styrene, and acrylic acid reacted with Cardura E10 in the presence of di-tert-butyl peroxide have a hydroxyl value of 150 mg KOH / g, a mass-average molecular weight of 9250 g / mol, and a theoretical glass transition temperature of 69°C. The solids content in the aprotic solvent mixture (methoxypropyl acetate and solvent naphtha 160 / 180) was 59.5% by mass.

[0130] Hydroxyfunctional poly(meth)acrylate A used in Comparative Example C1 C2 Polymerization products of butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, hydroxypropyl methacrylate, butanediol monoacrylate, acrylic acid, and styrene in the presence of di-tert-butyl peroxide have a hydroxyl value of 203 mg KOH / g, a mass-average molecular weight of 3600 g / mol, and a theoretical glass transition temperature of 30°C. The solids content in the aprotic solvent mixture (methoxypropyl acetate and solvent naphtha 160 / 180) was 65.1% by mass.

[0131] Hydroxyfunctional poly(meth)acrylate A used in Comparative Example C1 C3 Polymerization products of butyl acrylate, butyl methyl acrylate, hydroxyethyl methyl acrylate, butanediol monoacrylate, acrylic acid, and styrene in the presence of di-tert-butyl peroxide have a hydroxyl value of 116 mg KOH / g, a mass-average molecular weight of 8750 g / mol, and a theoretical glass transition temperature of 1.5°C. The solids content in the solvent naphtha 160 / 180 was 60.0% by mass.

[0132] Hydroxyfunctional poly(meth)acrylate A used in Comparative Example C1 C4 The polymerization product of hydroxyethyl acrylate and ethylhexyl acrylate in the presence of di-tert-butyl peroxide has a hydroxyl value of 130 mg KOH / g, a mass-average molecular weight of 4500 g / mol, and a theoretical glass transition temperature of -70°C. The solids content in the solvent naphtha 165 / 185 was 67.2% by mass.

[0133] Hydroxy-functional poly(meth)acrylate A containing urea crystals C5 In the presence of di-tert-butyl peroxide, butyl acrylate, hydroxyethyl acrylate, lauryl methacrylate, methacrylic acid, and styrene were polymerized in the solvent naphtha 160 / 180 to obtain a polymerization product. Subsequently, urea crystals were formed from hexamethylene diisocyanate and benzylamine in the presence of the polymerization product and butyl acetate. The obtained product had a hydroxyl value of 105 mg KOH / g, a mass-average molecular weight of 10500 g / mol, and a theoretical glass transition temperature of 4°C. The total solids content was 59.0% by mass. The urea crystal content was 4% by mass relative to the total mass of the preparation.

[0134] Hydrophilic oxide paste (hydrophilic silica paste) P First, hydroxy-functional poly(meth)acrylate A is obtained by polymerizing hydroxypropyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, acrylic acid, and styrene in the presence of di-tert-butyl peroxide in solvent naphtha 160 / 180 and butyl acetate. C6 Product A was produced. C6 It has a hydroxyl value of 156 mg KOH / g, a mass-average molecular weight of 4200 g / mol, and a theoretical glass transition temperature of 66°C. The solid content was 55.0% by mass.

[0135] 57pbw A C6 This was diluted in 9.3 parts by mass of butyl acetate. To this mixture, 8.7 parts by mass of Aerosil® 380 (manufactured by Evonik, with an average primary particle size of 7 nm and 380 nm) were added. 2 Hydrophilic silica with a specific surface area of ​​ / g, and further 25pbw A C6 The mixture was then homogenized in a dissolving machine. Finally, the mixture was ground in a stirring mill (model ZWM 46, abrasive medium 0.6-0.8 mm, type ER 120 A, packing level 85) with an energy input of 0.18 kWh per 1 kg of abrasive packing and a maximum paste temperature of 65°C.

[0136] The components of the masterbatch of comparative clear coat coating material C1 and the clear coat coating materials I1 and I2 of the present invention are shown in Table 1 below.

[0137] [Table 1]

[0138] Hardening agent components hardening agent As a curing agent, a 67.5% by mass solution of hexamethylene diisocyanate trimer (HDI-trimer) was used in a 1:1 (by mass ratio) mixture of butyl acetate and solvent naphtha (160 / 180).

[0139] Mixture of masterbatch components and hardener components Clear coat coating materials C1, I1, and I2 were prepared by mixing the mass masterbatch components and curing agent components shown in Table 2. The two components were mixed using a static mixing apparatus.

[0140] [Table 2]

[0141] Preparation of the test panel An electroplated steel sheet was coated with a water-based black monochromatic base coat material (dry film thickness 10-15 μm). After flash-off for 10 minutes at room temperature (23°C), the base coat material was cured in a convection oven at 60°C for at least 10 minutes. The thus coated panels were cooled to room temperature and then coated with the respective clear coat materials (dry film thickness 30 ± 5 μm). After flash-off for 10 minutes at room temperature (23°C), the clear coat material was cured in a convection oven at 60°C, 70°C, or 80°C for 30 minutes, as shown in the "Test Method" section and the table below.

[0142] result

[0143] [Table 3]

[0144] The Packmark resistance test (Table 3) clearly shows that the clear coat layer of the present invention, obtained from coating material I1, exhibits improved Packmark resistance even when cured at 60°C compared to the comparative clear coat layer obtained from comparative clear coat material C1 when cured at 80°C. When cured at 80°C, the clear coat layer of the present invention is completely resistant to Packmarks, while the comparative clear coat layer, when cured at 80°C, lacks Packmark resistance even after 24 hours.

[0145] [Table 4]

[0146] In sanding and polishing tests (Table 4), the clear coat layer of the present invention obtained from the clear coat material I1 showed no polishing marks whatsoever after 10 seconds of polishing, even when cured at 70°C. On the other hand, the comparative clear coat layer obtained from the comparative clear coat material C1 showed noticeable polishing marks when cured at 80°C.

[0147] [Table 5]

[0148] Chemical resistance tests conducted in a gradient oven (Table 5) show improved chemical resistance to high-concentration acids, such as 10% by mass of HCl in water and 5% by mass of sodium hydroxide solution in water. Furthermore, the clear coat layer obtained from the clear coat material I2 of the present invention exhibits particularly improved resistance to tree resin because it contains hydrophilic silica. Particularly surprising, hydrophilic metalloid oxides, such as hydrophilic silica, which are usually used as flow modifiers, were found to be suitable for improving the tree resin resistance of the clear coat layer. However, even the clear coat material I1 of the present invention, which does not contain hydrophilic silica, shows improved resistance to tree resin.

[0149] [Table 6]

[0150] * This is the average of two tests; ** This is the average value of four tests.

[0151] In the second chemical resistance test (Table 6), the clear coat layer containing hydrophilic silica showed particularly significant improvement even when cured at 70°C.

[0152] Therefore, the clear coat layer obtained according to the present invention exhibits significantly improved chemical resistance, even when cured at low temperatures.

Claims

1. A solvent-based two-component clear coat coating material, i. a. One or more poly(meth)acrylate polyols A having a hydroxyl value in the range of 160 to 240 mg KOH / g and a mass-average molecular weight in the range of 1000 to 7000 g / mol; and ii. a. One or more catalysts C for crosslinking hydroxyl groups and free isocyanate groups. Masterbatch components including, i. b. One or more curing agents B selected from the group consisting of diisocyanates and polyisocyanates. A hardening agent component containing and One or more aprotic organic solvents that can be contained in the masterbatch component, the curing agent component, or both the masterbatch component and the curing agent component; and Based on the total amount of aprotic organic solvents and protic solvents contained in the coating material, 0 to 10% by mass of the protic solvent in the masterbatch component. Coating materials including

2. The aforementioned masterbatch components iii. a. One or more unmodified metal oxides and / or metalloid oxides The coating material according to claim 1, further comprising:

3. The poly(meth)acrylate polyol A, in its polymerized form, contains the following monomers: a) One or more (meth)acrylic acid esters selected from alkyl (meth)acrylates and cycloalkyl (meth)acrylates; b) One or more hydroxyalkyl (meth)acrylates; and c) One or more vinyl aromatic monomers A coating material according to claim 1 or 2, comprising:

4. The poly(meth)acrylate polyol A is in a polymerized form d) Acrylic acid and / or methacrylic acid The coating material according to claim 3, further comprising:

5. The poly(meth)acrylate polyol comprises the following amounts of monomer: a) 20 to 40% by mass, preferably 25 to 35% by mass, of one or more (meth)acrylic acid esters selected from alkyl (meth)acrylates and cycloalkyl (meth)acrylates; b) 40 to 60% by mass, preferably 45 to 55% by mass, of one or more hydroxyalkyl (meth)acrylates; c) 10 to 30% by mass, preferably 15 to 25% by mass, of one or more vinyl aromatic monomers; and d) 0 to 5% by mass, preferably 0.5 to 4% by mass of acrylic acid and / or methacrylic acid Includes, The coating material according to claim 4, wherein the mass percentage is based on the total amount of all monomers present in the poly(meth)acrylate polyol in polymerized form.

6. a) Alkyl (meth)acrylate, C １ ~C ８ - Selected from alkyl (meth)acrylates, and cycloalkyl (meth)acrylate is C ３ ~C １０ - Selected from cycloalkyl (meth)acrylates; b) One or more hydroxyalkyl (meth)acrylates, C ２ ~C ８ - Selected from hydroxyalkyl (meth)acrylates; and c) The coating material according to claim 3, wherein one or more vinyl aromatic monomers are selected from styrene and alpha-methylstyrene.

7. The coating material according to claim 1 or 2, wherein the poly(meth)acrylate polyol A has a theoretical glass transition temperature of 50°C to 100°C according to the Flory-Fox formula.

8. The aforementioned poly(meth)acrylate polyol A is Hydroxyl values ​​in the range of 170–230 mg KOH / g, preferably 180–220 mg KOH / g; and / or Mass-average molecular weight in the range of 1500 to 6500 g / mol, preferably 2000 to 6000 g / mol; and / or Theoretical glass transition temperature according to the Flory-Fox equation: 55°C to 95°C, preferably in the range of 60°C to 90°C. A coating material according to claim 1 or 2, having the following characteristics.

9. The coating material according to claim 1 or 2, wherein the one or more catalysts C are selected from the group consisting of tertiary amines, inorganic metal-containing catalysts, and organometallic catalysts.

10. The coating material according to claim 9, wherein the organometallic catalyst is selected from the group consisting of zinc and bismuth salts of linear or branched, preferably branched, monocarboxylic acids, and the monocarboxylic acid has 4 to 14 carbon atoms.

11. The coating material according to claim 1 or 2, wherein the one or more curing agents B are selected from the group consisting of aliphatic diisocyanates and aliphatic polyisocyanates.

12. The coating material according to claim 1 or 2, wherein the polyisocyanate is a trimmer of diisocyanate.

13. The coating material according to claim 1 or 2, further comprising a sagging control agent, wherein the sagging control agent comprises urea crystals.

14. The coating material according to claim 2, wherein the unorganically modified metal oxide and / or metalloid oxide is selected from the group consisting of silica, alumina, and zirconia.

15. Based on the solid content obtained by subtracting the solid content of the hardener B from the solid content of the solvent-based two-component clear coat coating material, the following amounts of solid content are obtained: 65 to 90% by mass of one or more of the aforementioned poly(meth)acrylate polyols A; 0.05 to 1% by mass of one or more of the catalysts C; 0 to 5% by mass of one or more unmodified metal oxides and / or metalloids; 0 to 30% by mass of a further polymer binder different from the one or more poly(meth)acrylate polyols A; 0-5% by mass of urea crystals; and 0 to 10% by mass of one or more poly(meth)acrylate polyols A, one or more catalysts C, one or more unmodified metal oxides and / or metalloid oxides, a further polymer binder different from the one or more poly(meth)acrylate polyols A, and a coating additive different from urea crystals. Including; and Based on the solid content in the curing agent composition, the amounts of solids are as follows: 50 to 100% by mass of one or more curing agents B Including; and / or The coating material according to claim 1 or 2, wherein the molar ratio of OH groups contained in one or more poly(meth)acrylate polyols A to NCO groups contained in one or more curing agents B is in the range of 1:0.9 to 1:

2.

16. The following steps: i. A step of providing an uncoated or pre-coated substrate; ii. A step of applying at least one of the clear coat coating materials according to claim 1 or 2 to the uncoated or pre-coated substrate provided in step i to form a clear coat layer; and iii. The process of curing the clear coat layer. A method for coating a substrate, including [a specific component].

17. The method according to claim 16, wherein the curing of the clear coat layer is performed at a temperature in the range of 40°C to 90°C.

18. The method according to claim 17, wherein the substrate is a polymer substrate, preferably a vehicle body or a part thereof.

19. A coated substrate, wherein the substrate is either uncoated or pre-coated and includes a cured clear coat layer as a topcoat layer, the cured clear coat layer is formed from the coating material described in claim 1 or 2, and the substrate is a metal substrate, a glass substrate, a ceramic substrate, or a polymer substrate.

20. A method of using the solvent-based two-component clear coat coating material according to claim 1 or 2 for coating an uncoated or pre-coated substrate, preferably a vehicle body or a part thereof.

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