Application of Tung Oil in Polyurethane Compositions

Abstract

The present invention relates to a polyurethane composition comprising at least one polyurethane prepolymer containing isocyanate groups; and 0.7 to 2.5 wt. % tung oil, based on the total weight of the composition. The present invention further relates to a method for improving the chalk resistance of a coating of a polyurethane composition, especially when the coating has a high carbon black content, comprising adding 0.7 to 2.5 wt. % tung oil, based on the total weight of the polyurethane composition, to a polyurethane composition comprising at least one polyurethane prepolymer containing isocyanate groups prior to curing.

Description

[Technical field]

[0001] The present invention relates to the application of tung oil in polyurethane compositions, particularly for the purpose of improving the chalk resistance of polyurethane coating layers (especially when the carbon black content is high), and further to polyurethane compositions containing tung oil. [Background technology]

[0002] Curable polyurethane compositions crosslinked by the reaction of isocyanate groups with hydroxyl groups and / or moisture or water are used in many industrial applications, such as in the construction and manufacturing industries, as adhesives, sealants or coatings. Summary of the Invention [Problem to be solved by the invention]

[0003] However, when these polyurethane materials are used, for example when applied to roofs and walls, the surface of the cured polyurethane material layer often undergoes deterioration, such as chalking and cracking, over time as it is exposed to the environment.

[0004] It is known in the prior art that the addition of certain pigments, such as carbon black or titanium dioxide, can improve chalking resistance. However, if the amount of pigment added is excessive, especially carbon black, chalking and staining will occur, making it impossible to obtain an ideal appearance, and may also cause poor mechanical performance, aging and cracking of the material, and other adverse effects. [Means for solving the problem]

[0005] Therefore, the object of the present invention is to find a method that can further improve the chalking resistance of polyurethane coating layers.It is desired that such a method does not result in unacceptable carbon black staining, especially when a large amount of carbon black is added, for example, more than 9% or 15% by weight of the polyurethane composition.In addition, what is equally important is the need to simultaneously consider the curing properties of the polyurethane composition, so that the curing behavior and mechanical performance after curing of the polyurethane composition are not adversely affected or at most experience only a slight decrease, without affecting the use of the polyurethane composition.

[0006] Surprisingly, the inventors of the present application have already found that the above object can be achieved by a polyurethane composition as defined in claim 1, which contains tung oil in a proportion of 0.7-2.5% by weight, preferably 0.8-2.0% by weight, based on the total weight of the polyurethane composition. In particular, such polyurethane compositions allow the carbon black loading to be increased to levels of more than 15% by weight without significant chalking.

[0007] Moreover, as shown in the examples, the curing behavior and the mechanical performance of the polyurethane composition are not adversely affected.

[0008] Further aspects of the invention are the subject matter of the other independent claims. Particularly preferred embodiments of the invention are the subject matter of the dependent claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The first aspect of the present invention is - at least one polyurethane prepolymer containing isocyanate groups; - tung oil in a proportion ranging from 0.7 to 2.5% by weight relative to the total weight of the polyurethane composition; and - Carbon Black The present invention provides a polyurethane composition comprising:

[0010] Furthermore, a second aspect of the present invention provides a method for increasing the resistance of a polyurethane composition coating layer to chalking and / or carbon black staining, the method comprising adding tung oil to the polyurethane composition before curing in an amount of 0.7 to 2.5% by weight, based on the total weight of the polyurethane composition.

[0011] The term "molecular weight" refers to the molar mass (g / mol) of a molecule or molecular residue. The term "average molecular weight" refers to the number average molecular weight (Mn) of a polydisperse mixture of oligomeric or polymeric molecules or molecular residues. It is typically measured by gel permeation chromatography (GPC) using polystyrene as a standard.

[0012] The term "aromatic isocyanate" means an isocyanate in which the isocyanate group is attached directly to an aromatic carbon atom. Correspondingly, such an isocyanate group is called an "aromatic isocyanate group."

[0013] The term "aliphatic isocyanate" refers to an isocyanate in which the isocyanate group is attached directly to an aliphatic carbon atom. Correspondingly, such an isocyanate group is called an "aliphatic isocyanate group."

[0014] Substance names beginning with "poly", such as polyamine, polyol, or polyisocyanate, refer to substances in which each molecule formally contains two or more of the functional groups found in the substance name.

[0015] The term "room temperature" means 23°C.

[0016] The term "plasticizer" refers to a liquid or dissolved substance that is not chemically bonded to the cured polymer and that generally has a plasticizing effect on the polymer.

[0017] In the present invention, tung oil is a drying oil known per se. Drying oil is an oil that dries under the action of oxygen when exposed to air and forms a strong, elastic solid film. The main component of drying oil is glyceride of unsaturated fatty acid such as linolenic acid and linoleic acid, and drying oil generally has an iodine value of 130 or more, and includes natural drying oil and modified drying oil. So-called natural drying oils include, for example, tung oil, Chinese tallow tree seed oil, linseed oil, walnut oil, dehydrated castor oil, etc., and modified drying oils include, for example, maleic acid modified oil, ethylene modified oil, polymerized oil, and oxidized oil. Natural drying oil is mainly extracted from plants of the Euphorbiaceae family, and its preparation and extraction methods are widely known, and many products are already available on the market. Additionally, it is known in the art that drying oils can be added to certain coating compositions, such as sealants, to reduce surface tack, improve UV resistance, improve adhesion between the sealant and the topcoat, etc.

[0018] However, the inventors of the present application have unexpectedly discovered that in polyurethane coating compositions, tung oil, compared with other drying oils such as linseed oil, can produce very good resistance to chalking and carbon black staining, especially when added to isocyanate group-containing polyurethane prepolymers in the claimed proportion of 0.7-2.5 wt.%, preferably 0.8-2.0 wt.%, based on the total weight of the polyurethane composition before curing. When added in a specific amount, tung oil itself can provide sufficient anti-chalking effect when the carbon black content is very low, e.g., less than 4 or 5 wt.%, and can also perform very well in terms of preventing carbon black staining when the carbon black content is very high (e.g., 15 wt.% or more). Therefore, there is no need to worry about the chalking or staining problem caused by increasing the carbon black content to improve mechanical performance, and at the same time, in certain formulations, it is also possible to achieve the effect of significantly reducing the surface gloss and obtaining a very matte surface. Moreover, with the help of tung oil added in a specific amount, the curing and mechanical performance of the polyurethane composition is not significantly weakened.

[0019] Here, the amount of tung oil added is important. If too much is added, it may have a negative effect on the mechanical performance of the polyurethane coating layer, and if the amount is insufficient, especially when the carbon black content is high, no significant effect is obtained in terms of improving the chalking resistance. The preferred amount of tung oil added is 0.8-2.1 wt % or 0.9-2.0 wt % based on the total weight of the polyurethane composition.

[0020] In an advantageous embodiment of the present application, the polyurethane composition contains only a specific amount of tung oil as the drying oil, and contains very small amounts (e.g., less than 0.1% by weight, less than 0.05% by weight, less than 0.01% by weight, or less than 0.005% by weight) or preferably no other drying oils, such as linseed oil.

[0021] The polyurethane composition according to the present application may advantageously contain a high content of carbon black in order to maintain good mechanical performance and enhance the anti-chalking effect without causing the problem of carbon black staining. Preferably, the carbon black is contained in the composition in a proportion of 10% by weight or more, for example 15% by weight or more or 20% by weight or more, based on the total weight of the polyurethane composition.

[0022] Within the scope of the present application, suitable isocyanate group-containing polyurethane prepolymers are obtained in particular by reaction of at least one polyol with a superstoichiometric amount of at least one polyisocyanate. The reaction is preferably carried out at temperatures between 50 and 160° C., under moisture-free conditions, and optionally in the presence of a suitable catalyst. The NCO / OH ratio is preferably in the range of 1.3 / 1 to 5 / 1, preferably 1.5 / 1 to 4 / 1, in particular 1.8 / 1 to 3 / 1. The polyisocyanates, in particular monomeric diisocyanates, remaining in the reaction mixture after the conversion of the OH groups can be removed in particular by distillation, which is preferred when the NCO / OH ratio is high. Preferably, the content of free isocyanate groups in the resulting polyurethane prepolymer is 1 to 10% by weight, in particular 1.5 to 6% by weight. To prepare the polyurethane prepolymer, a plasticizer or a solvent may be optionally used at the same time, in which case the plasticizer or solvent used at the same time does not contain groups that are reactive with isocyanates.

[0023] The polyisocyanates used to prepare the isocyanate group-containing polyurethane prepolymers are in particular the commercially available polyisocyanates, such as, for example: aromatic di- or triisocyanates, preferably 4,4'- or 2,4'- or 2,2'-diphenylmethane diisocyanate or a mixture of these isomers (MDI), 2,4- or 2,6-toluene diisocyanate or a mixture of these isomers (TDI), MDI and a mixture of MDI homologues (polymeric MDI or PMDI), 1,3- or 1,4-benzene diisocyanate, 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-diisocyanatobiphenyl (TODI), dianisidine diisocyanate (DADI), tri(4-isocyanatophenyl)methane or tri(4-isocyanatophenyl)thiophosphate; preferably MDI or TDI; aliphatic, cycloaliphatic or arylaliphatic di- or triisocyanates, preferably 1,4-tetramethylene diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4- and / or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate (TMDI), 1,10-decamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, Isocyanates, lysine diisocyanate or lysine ester diisocyanate, cyclohexane-1,3- or -1,4-diisocyanate, 1-methyl-2,4- and / or -2,6-diisocyanatocyclohexane (H6TDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), perhydro 2,4'- and / or 4,4'-biphenylmethane diisocyanate (H 12 MDI), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane, m- or p-xylylene diisocyanate, tetramethyl-1,3- or 1,4-xylylene diisocyanate, 1,3,5-tris(isocyanatomethyl)benzene, bis(1-isocyanato-1-methylethyl)naphthalene, dimeric or trimeric fatty acid isocyanates, such as, in particular, 3,6-bis(9-isocyanatononyl)-4,5-bis(1-heptenyl)cyclohexene (dimeric diisocyanate); preferably H 12MDI or HDI or IPDI; - oligomers or derivatives of the aforementioned di- or triisocyanates, in particular derived from HDI, IPDI, MDI or TDI, in particular oligomers containing ureadione groups or isocyanurate groups or iminooxadiazinedione groups or their various radicals; or di- or polyhydric derivatives containing ester groups or urea groups or carbamate groups or biuret groups or allophanate groups or carbodiimide groups or uretonimine groups or oxadiazinetrione groups or their various radicals. In practice, polyisocyanates of this kind are generally mixtures of substances with different low degrees of polymerization and / or chemical structures. In particular, they have an average NCO functionality of 2.1 to 4.0.

[0024] Preferred polyisocyanates are aliphatic, cycloaliphatic or aromatic diisocyanates, in particular HDI, TMDI, cyclohexane-1,3- or -1,4-diisocyanate, IPDI, H 12 MDI, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane, XDI, TDI, MDI, 1,3- or 1,4-benzenediisocyanate, or naphthalene-1,5-diisocyanate (NDI).

[0025] Particularly preferred polyisocyanates are HDI, IPDI, H 12 MDI, TDI, MDI or a form of MDI that is liquid at room temperature, in particular HDI, IPDI, TDI or MDI.

[0026] The forms of MDI that are liquid at room temperature are 4,4'-MDI liquefied by partial chemical modification (in particular by using polyols for carbodiimidization, forming uretonimines or forming adducts) or mixtures of 4,4'-MDI with other MDI isomers (2,4'-MDI and / or 2,2'-MDI) and / or MDI oligomers and / or MDI homologues (PMDI), produced by special blending or obtained from preparation processes.

[0027] IPDI, TDI or MDI are most preferred.

[0028] Suitable polyols to be used for preparing the isocyanate group-containing polyurethane prepolymers are in particular the polyols or mixtures thereof which are commonly used commercially, in particular: - polyether polyols, in particular polyoxyalkylene diols and / or polyoxyalkylene triols, in particular the polymerization products of ethylene oxide or 1,2-propylene oxide or 1,2- or 2,3-butylene oxide or oxetane or tetrahydrofuran or mixtures thereof. These can be polymerized with the aid of initiator molecules having two or more active hydrogen atoms, such as, in particular, water, ammonia or compounds having several OH or NH groups, such as 1,2-ethanediol, 1,2- or 1,3-propanediol, neopentyl glycol, diethylene glycol, triethylene glycol, the isomeric dipropylene glycols or tripropylene glycols, the isomeric butanediols, pentanediols, hexanediols, heptanediols, octanediols, nonanediols, decanediols, undecanediols, 1,3- or 1,4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol or aniline, or mixtures of the abovementioned compounds. Likewise suitable are polyether polyols having polymer particles dispersed therein, in particular styrene / acrylonitrile (SAN) particles or polyurea or polyhydrazine dicarboxamide (PHD) particles dispersed therein. Preferred polyether polyols are polyoxypropylene diols or triols, or so-called ethylene oxide capped (EO capped) polyoxypropylene diols or triols. The latter are mixed polyoxyethylene / polyoxypropylene polyols, in particular obtained by using ethylene oxide to further alkoxylate the polyoxypropylene diols or triols after the end of the polypropoxylation reaction, and thus ultimately carrying primary hydroxyl groups.

[0029] Preferred polyether polyols have an unsaturation level of less than 0.02 mEq / g, especially less than 0.01 mEq / g. polyester polyols, also called oligoester alcohols, which are prepared by known methods, in particular by polycondensation of hydrocarboxylic acids or lactones or of aliphatic and / or aromatic polycarboxylic acids with diols or polyols. Preference is given to polyester diols obtained by reacting diols, such as in particular 1,2-ethanediol, diethylene glycol, 1,2-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, glycerol, 1,1,1-trimethylolpropane or mixtures of the abovementioned alcohols, with organic dicarboxylic acids or their anhydrides or esters, such as in particular succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid or hexahydrophthalic acid, or mixtures of the abovementioned acids, or polyester polyols derived from lactones, in particular ε-caprolactone. Particularly preferred are polyester polyols derived from adipic acid or sebacic acid or dodecanedicarboxylic acid and hexanediol or neopentyl glycol. - polycarbonate polyols, such as those obtainable, for example, by reaction of the abovementioned alcohols (used to form the polyester polyols) with dialkyl carbonates, diaryl carbonates or phosgene. - block copolymers having at least two hydroxyl groups and having at least two different blocks with polyether, polyester and / or polycarbonate structures of the type described above, in particular polyether polyester polyols. - Polyacrylate polyols and polymethacrylate polyols. - fats and oils with polyhydroxyl functions, for example natural fats and oils; or polyols produced by chemical modification of natural fats and oils, so-called oleochemical polyols, for example epoxy polyesters or epoxy polyethers obtained by epoxidation of unsaturated oils followed by ring opening with carboxylic acids or alcohols, or polyols obtained by hydroformylation and hydrogenation of unsaturated oils; or polyols obtained from natural fats and oils by decomposition processes such as alcoholysis or ozonolysis followed by chemical coupling, for example by transesterification or dimerization, of the decomposition products or the derivatives obtained thereby. Suitable decomposition products of natural fats and oils are in particular fatty acids and fatty alcohols and fatty acid esters, in particular methyl esters (FAMEs), which can be derivatized, for example, by hydroformylation and hydrogenation to hydroxyl fatty acid esters. - polyhydrocarbon polyols, also called oligohydrocarbon alcohols, such as polyolefins, polyisobutenes, polyisopentadienes, with polyhydroxyl functionality; ethylene / propylene, ethylene / butene or ethylene / propylene / diene copolymers with polyhydroxyl functionality, such as those prepared by Kraton Polymers; polymers of dienes, especially 1,3-butadiene, with polyhydroxyl functionality, especially those prepared by anionic polymerization; copolymers of dienes with polyhydroxyl functionality, such as 1,3-butadiene or diene mixtures with vinyl monomers, such as styrene, acrylonitrile, vinyl chloride, vinyl acetate, vinyl alcohol, isobutene and isopentadiene, such as epoxides or amino alcohols with carboxyl-capped acrylonitrile / butadiene copolymers (Emerald Performance Polymers). Polyhydroxyl functional acrylonitrile / butadiene copolymers which may be prepared from hydroxyl functional groups (commercially available from Materials under the name Hypro® CTBN or CTBNX or ETBN); as well as hydrogenated polymers or copolymers of hydroxyl functional dienes.

[0030] Mixtures of polyols are also particularly suitable.

[0031] Polyether polyols, polyester polyols, polycarbonate polyols, poly(meth)acrylate polyols or polybutadiene polyols are preferred.

[0032] Particular preference is given to polyether polyols, polyester polyols, especially aliphatic polyester polyols, or polycarbonate polyols, especially aliphatic polycarbonate polyols.

[0033] Polyether polyols, especially polyoxyethylene di- or triol, polyoxypropylene di- or triol, or ethylene oxide-capped polyoxypropylene di- or triol, are most preferred.

[0034] Preferred are polyols having an average molecular weight of 400 to 20000 g / mol, preferably 1000 to 10000 g / mol.

[0035] Polyols with an average OH functionality of 1.6 to 3 are preferred.

[0036] Polyols that are liquid at room temperature are preferred.

[0037] In the preparation of the isocyanate group-containing polyurethane prepolymers, difunctional or polyfunctional alcohol components are used, in particular 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,3-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol diol, dibromoneopentyl glycol, 1,2-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,2-octanediol, 1,8-octanediol, 2-ethyl-1,3- Hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,3- or 1,4-cyclohexanedimethanol, ethoxylated bisphenol A, propoxylated bisphenol A, cyclohexanediol, hydrogenated bisphenol A, dimeric fatty acid alcohols, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol, pentaerythritol, sugar alcohols, such as in particular xylitol, sorbitol or mannitol, or sugars, such as in particular sucrose, or alkoxylated derivatives of the aforementioned alcohols or mixtures of the aforementioned alcohols may also be used in combination.

[0038] Preferably, 1,4-butanediol is used in combination for applications requiring particularly high strength.

[0039] The isocyanate group-containing polyurethane prepolymer preferably has an average molecular weight of 1000 to 20000 g / mol, particularly 1500 to 10000 g / mol, and is preferably liquid at room temperature.

[0040] Preferably, the isocyanate group-containing polyurethane prepolymers according to the invention are polymers of polyether polyols and diisocyanates, in particular polymers of the abovementioned polyether polyols and diisocyanates such as TDI and MDI.

[0041] The isocyanate group-containing polyurethane prepolymer may be present in the polyurethane composition in a proportion of 20 to 45% by weight, for example 25 to 40% by weight, relative to the total weight of the composition before curing. Advantageously, the polymer substrate, i.e. the film-forming material, in the polyurethane composition according to the present application is substantially composed of said polyurethane prepolymer(s) containing isocyanate groups. This means that at least 95% by weight, preferably at least 97.5%, 99% or 100% by weight of the substrate is composed of said polyurethane prepolymer(s) containing isocyanate groups.

[0042] In addition to tung oil and at least one polyurethane prepolymer, preferably containing isocyanate groups, the composition further comprises one or more other components selected from catalysts, fillers, plasticizers, solvents, photocurable materials, light stabilizers, etc.

[0043] Suitable catalysts are, for example, catalysts used to promote the reaction of isocyanate groups, in particular organotin(IV) compounds, such as, in particular, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dibutyltin bis(acetylacetonate), dimethyltin dilaurate, dioctyltin diacetate, dioctyltin dilaurate or dioctyltin bis(acetylacetonate), bismuth(III) or zirconium(IV) complexes, in particular compounds with ligands selected from alkoxides, carboxylates, 1,3-diketo acid salts, oximates, 1,3-keto acid esters and 1,3-ketoamides, or compounds containing tertiary amino groups, such as, in particular, 2,2'-dimorpholinodiethyl ether (DMDEE). When used, the amount of catalyst is 0 to 1% by weight, preferably 0.01 to 0.5% by weight, relative to the total weight of the composition.

[0044] Also combinations of different catalysts are particularly suitable.

[0045] Suitable fillers are especially ground or precipitated calcium carbonate, optionally coated with fatty acids, especially stearic acid esters, barytes, quartz flour, quartz sand, dolomite, wollastonite, kaolin, calcined kaolin, layered silicates (for example mica or talcum), zeolites, aluminum hydroxide, magnesium hydroxide, silica (including highly dispersed silica produced by pyrolysis), cement, gypsum, fly ash, industrially produced carbon black, graphite, metal powders such as aluminum, copper, iron, silver or steel, PVC powder or hollow beads. If used, the amount of filler may be 5 to 60% by weight, preferably 10 to 50% by weight, relative to the total weight of the composition.

[0046] Suitable plasticizers are in particular carboxylic acid esters, such as phthalates, in particular diisononyl phthalate (DINP), diisodecyl phthalate (DIDP) or di(2-propylheptyl) phthalate (DPHP), hydrogenated phthalates, in particular diisononyl hydrogenated phthalate or diisononyl cyclohexane-1,2-dicarboxylate (DINCH), terephthalates, in particular dioctyl terephthalate, trimellitates, adipates, in particular dioctyl adipate, azelates, sebacates, benzoates, ethylene glycol ethers, ethylene glycol esters, organic phosphates or sulfonates, polybutenes, polyisobutenes, or plasticizers derived from natural fats and oils, in particular epoxidized soybean oil or linseed oil. When used, the amount of plasticizer is between 5 and 40% by weight, preferably between 10 and 30% by weight, relative to the total weight of the composition.

[0047] Photocurable materials undergo chemical changes in molecular structure easily and in a very short time when irradiated with light, which are accompanied by physical changes such as hardening. Compounds of this type include organic monomers, organic oligomers, resins, and other compositions containing these materials. Compounds of this type are generally unsaturated acrylic compounds, poly(vinyl cinnamate), and azide-containing compounds. When used, the amount of photocurable material may be 0.2-3% by weight, preferably 0.4-1.5% by weight, based on the total weight of the composition.

[0048] Suitable unsaturated acrylic compounds include acrylic and methacrylic acid monomers having one or more unsaturated groups, their oligomers, and mixtures thereof. Examples of oligomers having a molecular weight of less than 10,000 and acting as monomers include propylene (or butylene or ethylene) glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and 1,4-butyl dimethacrylate.

[0049] Poly(vinyl cinnamate) is a type of photosensitive resin having a cinnamoyl group as a photosensitive group, and includes poly(vinyl cinnamate) prepared by esterifying polyvinyl alcohol with cinnamic acid, as well as many poly(vinyl cinnamate) derivatives.

[0050] The azide-containing compound is a well-known photosensitive resin that has an azide group as the photosensitive group.

[0051] The light stabilizer is particularly a sterically hindered amine light stabilizer, and includes UV absorbers (which absorb light energy, for example, from sunlight and fluorescent lamps and convert it into harmless heat energy) and quenchers that eliminate active centers generated by light energy. In the case of resins that are susceptible to damage by light, a heat stabilizer and an antioxidant may be used in combination with the light stabilizer to significantly improve light resistance and weather resistance. When used, the amount of the light stabilizer may be 0.05 to 3 wt %, preferably 0.1 to 1.5 wt %, based on the total weight of the composition.

[0052] Most of these sterically hindered amine light stabilizers have already been commercialized, such as ADEKASTAB LA-52, LA-57, LA-62, LA-67, LA-63, LA-68, LA-77, LA-82 and LA-87 (manufactured by Asahi Denka Kogyo Co., Ltd.); di(2,2,6,6-tetramethyl-4-piperidinyl)sebacate; di(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, 1-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionyloxy]ethyl]-4-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidinylsuccinate. , dimethyl-1-(2-hydroxyethyl)-4-hydroxyl-2,2,6,6-tetramethylpiperidine condensation polymer, poly[[6-1-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][2,2,6,6-tetramethyl-4-piperidinyl]imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino], di(1,2,2,6,6-pentamethyl-4-piperidinyl)2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate, and the like.

[0053] When the composition of the present invention contains such photocurable materials or light stabilizers, particularly when the photocurable materials or light stabilizers are used in the amounts described above, the anti-chalking effect (especially when the carbon black content is high) can be further significantly improved without compromising the mechanical performance of the cured product.

[0054] The composition may contain other additives commonly used in polyurethane compositions. More specifically, the following auxiliaries and additives may be present: - inorganic or organic pigments, in particular titanium dioxide, chromium oxide or iron oxide; - fibres, in particular glass, carbon, metal, ceramic, plastic (for example polyamide or polyethylene) or natural fibres (for example wool, cellulose, hemp or sisal); - dye; - desiccants, in particular molecular sieve powders, calcium oxide, highly reactive isocyanates, such as p-toluenesulfonyl isocyanate, monomeric diisocyanates or orthoformates; - tackifiers, in particular organic alkoxysilanes, in particular epoxysilanes, such as, in particular, 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, (meth)acryloylsilanes, anhydrides, carbamates, alkylsilanes or iminosilanes or oligomeric forms of these silanes, or titanates; - latent hardeners or crosslinkers; - other catalysts which accelerate the reaction of isocyanate groups, in particular salts, soaps or complexes of tin, zinc, bismuth, iron, aluminium, molybdenum, molybdenum dioxide, titanium, zirconium or potassium, in particular tin(II) 2-ethylhexanoate, tin(II) neodecanoate, zinc(II) acetate, zinc(II) 2-ethylhexanoate, zinc(II) laurate, zinc(II) acetylacetonate, aluminium lactate, aluminium oleate, titanium diisopropoxide-bis(ethyl acetoacetate) or potassium acetate; compounds containing tert-amino groups, in particular N-ethyldiisopropylamine, N,N,N',N'-tetramethylalkylenediamines, pentamethylalkylenetriamines and their higher homologues, oxalate bis(N,N-diethylaminoethyl)amine, tris(3-dimethylaminopropyl)amine, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), N-alkylmorpholines, N,N'-dimethylpiperazines; aromatic nitrogen-containing compounds such as 4-dimethylaminopyridine, N-methylimidazole, N-vinylimidazole or 1,2-dimethylimidazole; organic ammonium compounds such as benzyltrimethylammonium hydroxide or alkoxylated tertiary amines; so-called "delayed action" catalysts, which are known variants of metal or amine catalysts; rheology modifiers, in particular thickeners, in particular layered silicates, for example bentonites, polyamides, polyamide waxes, polyurethanes, urea compounds, fumed silica, cellulose ethers or hydrophobically modified polyoxyethylenes; - natural resins, oils and fats; - silane coupling agents; - non-reactive polymers, in particular homo- or copolymers of unsaturated monomers, in particular the monomers are selected from ethylene, propylene, butene, isobutene, isopentadiene, vinyl acetate or alkyl (meth)acrylates, in particular polyethylene (PE), polypropylene (PP), polyisobutene, ethylene / vinyl acetate copolymers (EVA) or atactic poly-α-morphines (APAO); flame-retardant substances, in particular the above-mentioned aluminum hydroxide or magnesium hydroxide fillers, but also in particular organophosphates, such as, in particular, triethyl phosphate, tricresyl phosphate, triphenyl phosphate, diphenyl cresyl phosphate, isodecyl diphenyl phosphate, tris(1,3-dichloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, tris(2-ethylhexyl) phosphate, tris(chloroisopropyl) phosphate, tris(chloropropyl) phosphate, isopropylated triphenyl phosphate, mono-, bis- or tris(isopropylphenyl) phosphates with different degrees of isopropylation, resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate) or ammonium polyphosphate; additives, in particular wetting agents, levelling agents, defoamers, degassing agents, antioxidants, heat, light or UV stabilizers or biocides; or other materials commonly used in moisture curable compositions.

[0055] It may be advisable to chemically or physically dry certain materials prior to incorporation into the composition.

[0056] In the present application, the polyurethane prepolymer is advantageously a moisture-curable polyurethane composition that is crosslinked and cured by reaction of isocyanate groups with hydroxyl groups and / or moisture or water.

[0057] The polyurethane composition is in particular prepared by mixing the various components together under moisture-free conditions and stored in a moisture-proof container at ambient temperature. Suitable moisture-proof containers are in particular drums, cases, buckets, tubes, cans, bags, pouches, horse bags, boxes or pipes, in particular made of metal and / or plastic, optionally coated.

[0058] The mixing process is not particularly limited and is known to those skilled in the art, and various suitable mixing devices may be used to mix the components. Tung oil may be added at any point in the mixing process. For example, the polyurethane prepolymer may be first produced, and then tung oil and other additives may be added to the polyurethane prepolymer by stirring / mixing at room temperature. Advantageously, the mixing process is avoided from introducing moisture in the air. This may be achieved by applying a vacuum or by nitrogen protection.

[0059] The polyurethane composition is preferably in the form of a single component composition.

[0060] A composition referred to as a "single component" composition is one in which all components of the composition are contained in the same container and which is itself shelf stable, that is, with proper packaging and storage, shelf stable for extended periods of time, typically from several months to a year or more.

[0061] The curing process starts when the composition is applied. This results in a cured composition. The single-component composition is applied in its initial form, after which curing starts under the influence of moisture or water. The moisture necessary for the curing of the single-component composition preferably enters the composition by diffusion from the air (atmospheric moisture). In this process, a solid layer of the cured composition ("skin") is formed on the surface of the composition in contact with the air. The curing continues in a diffusion direction from the outside to the inside, and the skin becomes thicker and thicker, eventually covering the entirety of the applied composition. Moisture can also enter the composition additionally or completely from one or more substrates to which the composition has already been applied, and / or can come from accelerator components that are mixed into the composition during application or that come into contact with it after application, for example by sprinkling or spray coating.

[0062] The composition is preferably applied at ambient temperature, in particular within the range of about 0 to 50°C, preferably within the range of 5 to 40°C.

[0063] The composition preferably cures at ambient temperature.

[0064] The composition is preferably an adhesive or a sealant or a coating.

[0065] The composition is particularly suitable for use as an adhesive and / or sealant in bonding and sealing applications, especially in the building and manufacturing industries, preferably in the manufacture of vehicles, especially in the bonding of parquet floors, bonding of installation parts, sealing of cavities, assembly, bonding of modules, bonding of vehicle bodies, bonding of window panes, or sealing of connectors. Elastic bonding in vehicle construction is, for example, bonding of parts (e.g. plastic covers, decorative strips, flanges, bumpers, cabs or other mountable parts) to the painted body of an automobile, or bonding of window panes to the body, where the vehicle is particularly a car, truck, bus, railroad car or ship.

[0066] Preferably, the compositions of the present invention are used for elastic sealing of various connectors, joints or cavities in automobile manufacturing, especially for component bonding, cavity sealing, body bonding and window glass bonding.

[0067] The present invention therefore also relates to the results obtained by the above mentioned adhesive or sealing applications. EXAMPLES

[0068] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the described examples.

[0069] [Table 1]

[0070] 2. Preparation of Polyurethane Prepolymer Prepolymer P1: 2793 g of polyether triol (EXCENOL® 4030, Asahi), 1787 g of polyether diol (Acclaim® 4200, Covestro), 598 g of diisodecyl phthalate (Jayflex® DIDP) and 820 g of MDI (Desmodur® 44 MC, Covestro) were added to the reactor, stirred and heated to 80° C. under nitrogen protection, and reacted until the end of the reaction. An isocyanate-capped polyurethane prepolymer P1 was finally obtained, having an isocyanate group content of about 2.4%.

[0071] Prepolymer P2: 4051 g of polyether triol (VORANOL® CP 4755, Dow Chemicals), 1787 g of polyether diol (Acclaim® 4755, Covestro), 1172 g of diisodecyl phthalate (Jayflex® DIDP) and 675 g of MDI (Desmodur® 44 MC, Covestro) were added to the reactor, stirred and heated to 80° C. under nitrogen protection, and reacted until the end of the reaction. An isocyanate-capped polyurethane prepolymer P2 with an isocyanate group content of about 2% was finally obtained.

[0072] Prepolymer P3: 1632 g of polyether diol (Acclaim® 4200, Covestro), 4410 g of polyether triol (VORANOL® CP 4755, Dow Chemicals) and 800 g of IPDI (Desmodur® I, Covestro) were added to the reactor, stirred and heated to 80° C. under nitrogen protection, and reacted until the end of the reaction. A polyurethane prepolymer capped with isocyanate groups was finally obtained; the polyurethane prepolymer P3 had an isocyanate group content of about 2.1%.

[0073] 3. General compounding process of polyurethane composition The specified weight parts of the components shown in Table 1 were added sequentially to a twin-axis kneader at room temperature, mixed under vacuum, and processed to form a uniform paste, which was immediately filled into an aluminum tube with an inner coating and then sealed. Thus, Examples E0 to E7 were produced.

[0074] The compositions thus prepared were then tested for various properties as described below.

[0075] 4. Contents of the performance test The tensile strength and elongation at break were tested according to GB / T 528-2009. The test speed was 200 mm / min, and the specimen thickness was approximately 2 mm. The specimens were cured at 23°C and 50% relative humidity for 7 days.

[0076] The Shore A hardness was tested according to GB / T 531.1-2008. The thickness of the specimens was approximately 6 mm, and the specimens were cured at 23°C and 50% relative humidity for 7 days.

[0077] Surface drying time was tested according to GB / T 13477.5-2002. Surface drying time results were accurate to 2 minutes.

[0078] The chalking degree evaluation was carried out according to the adhesive tape test described in GB / T 1766-2008. The thickness of the samples was about 2 mm, and the samples were cured at 23°C and 50% relative humidity for 7 days.

[0079] [Table 2-1]

[0080] [Table 2-2]

Claims

1. at least one polyurethane prepolymer containing isocyanate groups; tung oil in a proportion ranging from 0.7 to 2.5% by weight, and preferably from 0.8 to 2.0% by weight, relative to the total weight of the composition; and - Carbon black 1. A polyurethane composition comprising:

2. 2. The polyurethane composition according to claim 1, characterized in that the polyurethane prepolymer containing isocyanate groups is a polymer of a polyether polyol and a diisocyanate, in particular a polymer of a polyoxyalkylene diol and / or a polyoxyalkylene triol and a diisocyanate, in particular TDI and / or MDI.

3. The polyurethane composition according to claim 1 or 2, characterized in that the polyurethane prepolymer containing an isocyanate group is contained in the polyurethane composition in a proportion of 20 to 45% by weight, preferably 25 to 40% by weight, based on the total weight of the composition before curing.

4. 4. A polyurethane composition according to claim 1, characterized in that in addition to tung oil, the polyurethane composition comprises less than 0.1% by weight, in particular less than 0.05% by weight or preferably less than 0.005% by weight of other drying oils, or more preferably no other drying oils.

5. 5. Polyurethane composition according to claim 1, characterized in that it contains carbon black in a proportion of at least 9% by weight, preferably at least 15% by weight, relative to the total weight of the polyurethane composition.

6. The polyurethane composition according to any one of claims 1 to 5, characterized in that the polyurethane composition contains a photocurable material and / or a light stabilizer.

7. 7. The polyurethane composition of claim 6, wherein the photocurable material is selected from unsaturated acrylic compounds, poly(vinyl cinnamate), and azide-containing compounds, preferably unsaturated acrylic compounds.

8. The polyurethane composition according to claim 6, wherein the light stabilizer is a sterically hindered amine light stabilizer.

9. A method for improving the chalking resistance of a polyurethane composition coating layer, comprising adding tung oil to a polyurethane composition before curing in an amount of 0.7 to 2.5% by weight, preferably 0.8 to 2.0% by weight, based on the total weight of the polyurethane composition, the polyurethane composition containing carbon black and at least one polyurethane prepolymer containing isocyanate groups.

10. 10. The method according to claim 9, characterized in that the polyurethane composition contains carbon black in a proportion of at least 9% by weight, preferably at least 15% by weight relative to the total weight of the polyurethane composition.

11. 11. The method according to claim 9 or 10, characterized in that a photocurable material and / or a light stabilizer is added to the polyurethane composition.

12. 12. The method of claim 11, wherein the photocurable material is selected from unsaturated acrylic compounds, poly(vinyl cinnamate), and azide-containing compounds, preferably unsaturated acrylic compounds, and / or the light stabilizer is a sterically hindered amine light stabilizer.

13. Use of the polyurethane composition according to any one of claims 1 to 8 as adhesive and / or sealant for bonding and sealing, especially in the building and manufacturing industries, preferably in the manufacture of vehicles.

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