Polyisocyanate composition, coating composition and application

Abstract

According to the polyisocyanate composition, the coating composition and the application, the polyisocyanate composition provided by the invention has relatively low viscosity, good cross-linking property and heat resistance; a coating film obtained on the basis of the polyisocyanate composition provided by the invention has comprehensive properties such as good glossiness, alcohol wiping resistance, appearance and the like. The polyisocyanate composition contains an isocyanurate group, the polyisocyanate composition contains a polymer A, a polymer B and a polymer C, the mass content of the polymer A in the polyisocyanate composition is a, the mass content of the polymer B in the polyisocyanate composition is b, the mass content of the polymer C in the polyisocyanate composition is c, and b / (a + c) is larger than or equal to 10 and smaller than or equal to 150; uV absorption peaks exist in a measurement spectrogram, obtained through gel permeation chromatography, of the polyisocyanate composition, the heights of the UV absorption peaks of the polymer A, the polymer B and the polymer C are x, y and z respectively in sequence, and y / (x + z) is larger than or equal to 0.1 and smaller than or equal to 10.

Description

Technical Field

[0001] The present invention relates to the technical field of polyisocyanate compositions, and in particular to a polyisocyanate composition, a coating composition and applications. Background Art

[0002] Aliphatic polyisocyanates containing isocyanurate structures are widely used in high-end fields such as automotive original paint, repair paint and varnish due to their excellent weather resistance, chemical resistance and heat resistance. In recent years, due to the continuous improvement of environmental protection requirements, in order to reduce the use of organic solvents in the application process of coating compositions, polyisocyanates used as curing agents have gradually developed in the direction of low viscosity.

[0003] Currently disclosed methods for preparing low-viscosity polyisocyanate compositions containing isocyanurate structures mainly include reducing the reaction conversion rate and introducing modified components, for example:

[0004] US4801663A describes a low-viscosity polyisocyanate composition, in which the proportion of isocyanurate monocyclic polymer is as high as 70-75%, but its reaction conversion rate can only reach 12-21%, and the total yield of the reaction is significantly reduced. This method requires the removal of a large amount of unreacted monomers from the final reaction product, which greatly increases the cost of the method.

[0005] The allophanate structure obtained by monohydric alcohol modification in CN101291970A can reduce the viscosity of the polyisocyanate composition, but the allophanate structure obtained by monohydric alcohol modification has poor crosslinking and compatibility, and the appearance and glossiness of the resulting paint film are insufficient when applied to the coating composition.

[0006] US5354834A reduces the viscosity of the product by regulating the content of uretdione dimer in the polyisocyanate composition to be higher than 10%. Increasing the content of uretdione dimer is beneficial to reducing the viscosity of the composition, but uretdione has a linear structure and poor crosslinking and compatibility, which is unfavorable to the hardness and appearance of the paint film, and there is a situation where the monomer content increases during storage.

[0007] CN1757639A discloses a method for preparing a low-viscosity polyisocyanate. The patent uses a quaternary ammonium salt or phosphonium salt of polyfluoro acid as a catalyst to prepare a polyisocyanate containing an iminooxadiazinedione group, which can reduce the viscosity of the polyisocyanate composition. However, the iminooxadiazinedione structure has poor stability, and the introduction of fluorine makes the method unsafe and environmentally friendly.

[0008] It is known from the prior art that it is difficult to simultaneously ensure low viscosity and good crosslinking property of the polyisocyanate composition obtained by allophanate modification. The viscosity of the isocyanuric acid type polyisocyanate composition can be reduced by uretdione or iminooxadiazinedione modification, but it is difficult to simultaneously ensure the thermal stability of the composition and to make the prepared paint film have excellent performance. Therefore, it is necessary to develop an aliphatic polyisocyanate that can reduce the viscosity while maintaining good crosslinking property and thermal stability, thereby ensuring the excellent performance of the obtained paint film. Summary of the invention

[0009] The present invention provides a polyisocyanate composition, a coating composition and applications. The polyisocyanate composition provided by the present invention can take into account low viscosity, good cross-linking and heat resistance. The coating film obtained based on the polyisocyanate composition provided by the present invention can take into account comprehensive properties such as good gloss, alcohol abrasion resistance and appearance.

[0010] To achieve the purpose, the present invention provides the following technical solutions:

[0011] The present invention provides a polyisocyanate composition, wherein the polyisocyanate composition contains isocyanurate groups.

[0012] The polyisocyanate composition contains polymer A, polymer B and polymer C, and the mass contents of polymer A, polymer B and polymer C in the polyisocyanate composition are a, b and c respectively, and satisfy 10≤b / (a+c)≤150;

[0013] The polyisocyanate composition has a UV absorption peak in a measurement spectrum obtained by gel permeation chromatography, and the heights of the UV absorption peaks of polymer A, polymer B and polymer C are x, y, and z, respectively, and satisfy 0.1≤y / (x+z)≤10;

[0014] The polymer A is a polymer of two monomers, wherein the monomers in the two monomers are diisocyanate and an optional alcohol compound;

[0015] The polymer B is a polymer of three monomers, and the monomers in the three monomers are diisocyanate and an optional alcohol compound;

[0016] The polymer C is a polymer of four molecules of monomers, and the monomers in the four molecules of monomers are diisocyanate and an optional alcohol compound.

[0017] Further, the polymer A mainly comprises one or more of a uretdione dimer formed by the reaction of two molecules of diisocyanate, and a carbamate formed by the reaction of one molecule of diisocyanate and one molecule of an alcohol compound;

[0018] And / or, the polymer B mainly comprises one or more of a trimer formed by the reaction of three molecules of diisocyanate, and an allophanate formed by the reaction of two molecules of diisocyanate and one molecule of an alcohol compound; the trimer formed by the reaction of three molecules of diisocyanate comprises one or more of an isocyanurate trimer, an iminooxadiazinedione trimer, and a uretdione trimer;

[0019] And / or, the polymer C mainly comprises one or more of isocyanurate-uretdione-based tetramer, iminooxadiazinedione-uretdione-based tetramer, and uretdione-based tetramer.

[0020] Furthermore, in the polymer A, the uretdione dimer and the carbamate have the following structural formulas (I) and (II) respectively:

[0021]

[0022] In the structural formula (I) and the structural formula (II), each R1, R2, and R3 is independently a straight-chain alkyl group, a branched-chain alkyl group, or a cycloalkyl group, and the number of carbon atoms is independently 3-14;

[0023] In the polymer B, the isocyanurate trimer, the iminooxadiazinedione trimer, the allophanate and the uretdione trimer have the following structural formulas (III), (IV), (V) and (VI) respectively:

[0024]

[0025] In the structural formula (III), structural formula (IV), structural formula (V) and structural formula (VI), each R4, each R5, each R6, R7, and each R8 are independently a linear alkyl group, a branched alkyl group or a cycloalkyl group, and the number of carbon atoms is independently 3-14;

[0026] In the polymer C, the isocyanurate-uretdione tetramer has the following structural formula (VII), the iminooxadiazinedione-uretdione tetramer is one or more compounds having the following structural formulas (VIII), (IX), and (X), and the uretdione tetramer has the following structural formula (XI):

[0027]

[0028]

[0029] In the structural formula (VII), structural formula (VIII), structural formula (IX), structural formula (X) and structural formula (XI), each R9, each R 10 , each R 11 , each R12 , each R 13 Each is independently a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, and each has independently 3 to 14 carbon atoms.

[0030] Specifically, the alcohol compound is introduced as a separate reaction raw material and / or as a solvent when preparing the polyisocyanate composition;

[0031] The alcohol compound is selected from one or more of aliphatic monohydric alcohols and aliphatic dihydric alcohols.

[0032] Preferably, the content of the polymer B in the polyisocyanate composition is 25-75 wt %.

[0033] Specifically, the viscosity of the polyisocyanate composition measured at 25° C. is 100-4000 mPa·s.

[0034] Preferably, the polyisocyanate composition contains iminooxadiazinedione groups, and the ratio of the molar amount d of the iminooxadiazinedione groups to the molar amount m of the isocyanurate groups is 0.01-0.15;

[0035] And / or, the polyisocyanate composition contains uretdione groups, and the ratio of the molar amount e of the uretdione groups to the molar amount m of the isocyanurate groups is 0.01-0.05.

[0036] Further, the polyisocyanate composition is derived from aliphatic diisocyanate and / or alicyclic diisocyanate.

[0037] The present invention also provides a coating composition, wherein the coating composition comprises the polyisocyanate composition described above.

[0038] The present invention also provides the use of the polyisocyanate composition described above in improving the gloss, alcohol abrasion resistance and / or appearance of a paint film;

[0039] The appearance includes the sharpness and surface smoothness of the paint film.

[0040] The technical solution provided by the present invention has the following beneficial effects:

[0041] The content relationship among the diisocyanate monomer-derived diisocyanate polymer A, trimolecular polymer B and tetramolecular polymer C in the polyisocyanate composition satisfies 10≤b / (a+c)≤150, and the relationship among the heights of the UV absorption peaks of the polymers A, B and C in gel permeation chromatography satisfies 0.1≤y / (x+z)≤10, so that the product can have lower viscosity, better crosslinking property and thermal stability at the same time. After being used in the coating composition, the amount of solvent used can be significantly reduced, which is more environmentally friendly, and also has better comprehensive properties of the paint film, and can well take into account and improve multiple aspects such as gloss, appearance and alcohol abrasion resistance. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0044] The present invention provides a polyisocyanate composition, wherein the polyisocyanate composition contains isocyanurate groups.

[0045] The polyisocyanate composition contains polymer A, polymer B and polymer C, and the mass contents of polymer A, polymer B and polymer C in the polyisocyanate composition are a, b and c respectively, and satisfy 10≤b / (a+c)≤150;

[0046] The polyisocyanate composition has a UV absorption peak in a measurement spectrum obtained by gel permeation chromatography (GPC), and the heights of the UV absorption peaks of the polymer A, polymer B, and polymer C are x, y, and z, respectively, and satisfy 0.1≤y / (x+z)≤10;

[0047] The polymer A is a polymer of two monomers, wherein the monomers in the two monomers are diisocyanate and an optional alcohol compound;

[0048] The polymer B is a polymer of three monomers, and the monomers in the three monomers are diisocyanate and an optional alcohol compound;

[0049] The polymer C is a polymer of four molecules of monomers, and the monomers in the four molecules of monomers are diisocyanate and an optional alcohol compound.

[0050] Herein, "optional" means containing or not containing. For example, in polymer A, the monomers in the two molecules of monomers are diisocyanate and an optional alcohol compound, and the two molecules of monomers contain or do not contain the alcohol compound.

[0051] The present inventors have unexpectedly found through extensive research that, in a polyisocyanate composition containing an isocyanurate group, the contents of a polymer A derived from a di-molecular monomer, a polymer B derived from a trimerizable monomer, and a polymer C derived from a tetra-molecular monomer satisfy 10≤b / (a+c)≤150, and the heights of the UV absorption peaks of the polymers A, B, and C in a measurement spectrum obtained by gel permeation chromatography (GPC) of the polyisocyanate composition satisfy 0.1≤y / (x+z)≤10. The composition can take into account low viscosity, good cross-linking properties, and heat resistance. When used in a coating composition, it can take into account the improvement of comprehensive properties such as gloss, appearance, and alcohol abrasion resistance of the coating film.

[0052] Typically, the polyisocyanate composition containing isocyanurate groups mainly includes a mixture of polymers of different molecular weights generated by polymerization reaction of aliphatic and / or alicyclic diisocyanates under the action of a trimerization catalyst, including trimolecular polymers, pentamolecular polymers, heptamolecular polymers, nonamolecular polymers, multimolecular polymers, etc. At the same time, due to the presence of modified components, it also includes a certain amount of dimolecular polymers and tetramolecular polymers, and the modified components are brought in, for example, by alcohol compounds and / or high temperature conditions.

[0053] In the present invention, the polymer A is a polymer of two molecules of monomers, and the polymer A includes one or more of a polymer in which the monomers in the two molecules of monomers are diisocyanates, and a polymer in which the monomers in the two molecules of monomers are diisocyanates and alcohol compounds. The polymer A is a di-molecular polymer derived from a diisocyanate monomer, and the monomers in the two molecules of monomers forming the di-molecular polymer are diisocyanates and optional alcohol compounds. Specifically, the polymer in polymer A includes one or more of a di-molecular polymer with diisocyanates as monomers, and a di-molecular polymer with diisocyanates and alcohol compounds as monomers; the mass content a refers to the total amount of these di-molecular polymers. Further, the polymer A mainly includes a uretdione dimer formed by the reaction of two molecules of diisocyanates, and one or more of a carbamate formed by the reaction of one molecule of diisocyanate and one molecule of alcohol compounds, that is, the polymer A mainly includes one or more of the above-mentioned uretdione dimers and carbamates. Further, in the polymer A, the uretdione dimer and the carbamate have the following structural formulas (I) and (II) respectively:

[0054]

[0055] Wherein, in the structural formula (I) and the structural formula (II), each R1, R2, and R3 are independently a linear alkyl group, a branched alkyl group, or a cycloalkyl group, and the number of carbon atoms is independently 3 to 14. In some examples, the polymer A mainly comprises the polymer of the above structural formula (I) and / or structural formula (II).

[0056] In the present invention, the polymer B is a polymer of trimolecular monomers, and the polymer B includes one or more of a polymer in which the monomer in the trimolecular monomer is a diisocyanate, and a polymer in which the monomer in the trimolecular monomer is a diisocyanate and an alcohol compound. The polymer B is a trimolecular polymer derived from a diisocyanate monomer, and the monomer in the trimolecular monomer forming the trimolecular polymer is a diisocyanate and an optional alcohol compound. Specifically, the polymer in polymer B includes one or more of a trimer with diisocyanate as a monomer, and a trimer with diisocyanate and an alcohol compound as a monomer; the mass content b is in terms of the total amount of these trimolecular polymers. Further, the polymer B mainly includes one or more of a trimer formed by the reaction of three molecules of diisocyanate, and an allophanate formed by the reaction of two molecules of diisocyanate and one molecule of an alcohol compound; specifically, the trimer formed by the reaction of three molecules of diisocyanate includes one or more of an isocyanurate trimer, an iminooxadiazinedione trimer, and a uretdione trimer. Furthermore, in the polymer B, the isocyanurate trimer, the iminooxadiazinedione trimer, the allophanate and the uretdione trimer have the following structural formulas (III), (IV), (V) and (VI) respectively:

[0057]

[0058] In the structural formula (III), each R4 is independently a straight-chain alkyl group, a branched alkyl group or a cycloalkyl group, and the number of carbon atoms is independently 3-14;

[0059] In the structural formula (IV), each R5 is independently a straight-chain alkyl group, a branched alkyl group or a cycloalkyl group, and the number of carbon atoms is independently 3-14;

[0060] In the structural formula (V), each R6 and R7 is independently a straight-chain alkyl group, a branched alkyl group or a cycloalkyl group, and the number of carbon atoms is independently 3-14;

[0061] In the structural formula (VI), each R8 is independently a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, and the number of carbon atoms is independently 3-14.

[0062] In some examples, the polymer B mainly comprises polymers of the above structural formula (III), structural formula (IV), structural formula (V) and / or structural formula (VI).

[0063] In the present invention, the polymer C is a polymer of four molecules, and the polymer C includes one or more of a polymer in which the monomer in the four molecules is a diisocyanate, and a polymer in which the monomer in the four molecules is a diisocyanate and an alcohol compound. The polymer C is a four-molecule polymer derived from a diisocyanate monomer, specifically, the polymer C is a polymer of four molecules, and the four molecules are diisocyanates and optional alcohol compounds. Specifically, the polymer in polymer C includes one or more of a four-molecule polymer with diisocyanates as monomers, and a four-molecule polymer with diisocyanates and alcohol compounds as monomers; the mass content c is in terms of the total amount of these four-molecule polymers. Further, the polymer C mainly includes one or more of isocyanurate-uretdione-based tetramers (as shown in the following structural formula (VII)), iminooxadiazinedione-uretdione-based tetramers (as shown in the following structural formulas (VIII), (IX), (X) compounds), and uretdione-based tetramers (as shown in the following structural formula (XI)). More specifically, the isocyanurate-uretdione tetramer is formed by the reaction of one molecule of isocyanurate trimer and one molecule of uretdione dimer; the iminooxadiazinedione-uretdione tetramer is formed by the reaction of one molecule of iminooxadiazinedione trimer and one molecule of uretdione dimer. In some examples, the polymer C mainly comprises the isocyanurate-uretdione tetramer, the iminooxadiazinedione-uretdione tetramer and the uretdione tetramer.

[0064]

[0065] In the structural formulas (VII), (VIII), (IX), (X), and (XI), each R9, each R 10 , each R 11 , each R 12 , each R 13 Each is independently a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, and each has 3 to 14 carbon atoms.

[0066] In the polyisocyanate composition of the present invention, the mass contents of polymer A, polymer B and polymer C in the polyisocyanate composition are respectively a, b and c, and satisfy 10≤b / (a+c)≤150; at the same time, in the measurement spectrum obtained by gel permeation chromatography (GPC) of the polyisocyanate composition, there is a UV absorption peak of the polyisocyanate composition, and the heights of the UV absorption peaks corresponding to polymer A, polymer B and polymer C are respectively x, y and z, and satisfy 0.1≤y / (x+z)≤10. The inventors have found through extensive research that when b / (a+c)<10, the crosslinking property of the polyisocyanate composition is poor; and when b / (a+c)>150, the viscosity of the polyisocyanate composition is high; when y / (x+z)<0.1, the thermal stability of the polyisocyanate composition is poor, and when y / (x+z)>10, the compatibility of the polyisocyanate composition is poor. The inventors unexpectedly found that when 10≤b / (a+c)≤150 and 0.1≤y / (x+z)≤10 are satisfied at the same time, the polyisocyanate composition can take into account both low viscosity and good crosslinking and thermal stability. When used in coatings, it can improve the comprehensive properties of the paint film and help take into account comprehensive properties such as good gloss, solvent resistance and appearance.

[0067] In some examples, b / (a+c) is 10, 15, 20, 30, 50, 70, 100, 120, 150, etc.; in some examples, y / (x+z) is 0.1, 0.2, 0.5, 1, 3, 5, 7, 10, etc. Preferably, b / (a+c) is 20-150, and y / (x+z) is 0.5-10. The polyisocyanate composition meeting the preferred conditions has better application performance, for example, when used in a coating film, it can give the coating film a better appearance and glossiness.

[0068] In the present invention, the content of polymer A, polymer B and polymer C in the polyisocyanate composition can be measured by gel permeation chromatography equipped with a differential detector, and the content can be measured by area normalization method using the differential detector, and the measured content is taken as the mass content.

[0069] In some embodiments, the alcohol compound is introduced as a separate reaction raw material and / or as a solvent when preparing the polyisocyanate composition; for example, the alcohol compound is selected from one or more of aliphatic monohydric alcohols and aliphatic dihydric alcohols. Among them, the monohydric alcohol can be one or more of ethanol, n-propanol, n-butanol, n-hexanol, isooctyl alcohol, etc.; the dihydric alcohol can be one or more of ethylene glycol, 1,3-butanediol, 1,4-hexanediol, 1,3-diethylhexanediol, etc.

[0070] In a preferred embodiment, the content of polymer B in the polyisocyanate composition is 25-75wt%. When the content of polymer B formed by trimers is above 25wt%, the viscosity of the polyisocyanate composition can be effectively reduced, thereby reducing the use of solvents when used as a coating; when the content of polymer B formed by trimers is less than 75wt%, the polyisocyanate composition can have good crosslinking properties, thereby ensuring the excellent application performance of the composition.

[0071] In a preferred embodiment, the viscosity of the polyisocyanate composition measured at 25° C. is 100-4000 mPa·s. When the viscosity is lower than 100 mPa·s, the crosslinking property of the polyisocyanate composition is poor; when the viscosity is higher than 4000 mPa·s, the amount of solvent used in the polyisocyanate composition when used as a coating is large, which is not conducive to environmental protection.

[0072] Preferably, the polyisocyanate composition of the present invention contains isocyanurate groups, iminooxadiazinedione groups and uretdione groups simultaneously.

[0073] Furthermore, the isocyanurate group is a functional group of a polyisocyanate formed by three molecules of diisocyanate monomers, and its specific structural formula is shown below:

[0074]

[0075] Furthermore, the iminooxadiazinedione group is a functional group of a polyisocyanate formed by three molecules of diisocyanate monomers, and its specific structural formula is shown below:

[0076]

[0077] Furthermore, the uretdione group is a functional group of a polyisocyanate formed by two molecules of diisocyanate monomers, and its specific structural formula is shown below:

[0078]

[0079] In a preferred embodiment, the ratio of the molar amount d of the iminooxadiazinedione group to the molar amount m of the isocyanurate group contained in the polyisocyanate composition is 0.01-0.15. The polyisocyanate composition having a molar ratio of the iminooxadiazinedione group to the isocyanurate group within the above preferred range is conducive to further balancing lower viscosity and better crosslinking properties.

[0080] In a preferred embodiment, the ratio of the molar amount e of the uretdione group contained in the polyisocyanate composition to the molar amount m of the isocyanurate group is 0.01-0.05. The polyisocyanate composition having a molar ratio of uretdione group to isocyanurate group within the above preferred range is conducive to further taking into account lower viscosity, better crosslinking and thermal stability.

[0081] The polyisocyanate composition is derived from an aliphatic diisocyanate and / or an alicyclic diisocyanate, and specifically, the polyisocyanate composition is prepared based on an aliphatic diisocyanate and / or an alicyclic diisocyanate. The aliphatic diisocyanate and / or the alicyclic diisocyanate, i.e., a diisocyanate monomer, is preferably selected from one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate, preferably pentamethylene diisocyanate and / or hexamethylene diisocyanate.

[0082] The following is an exemplary description of the preparation method of the polyisocyanate composition of the present invention:

[0083] In some examples, the polyisocyanate composition of the present invention can be prepared by a preparation method comprising the following steps, wherein the diisocyanate monomer used in the following steps is an aliphatic diisocyanate monomer and / or an alicyclic diisocyanate monomer:

[0084] S1: adding a trimerization catalyst to a diisocyanate monomer, causing the monomer to react to a desired conversion rate, and stopping the reaction by adding a terminator to obtain a reaction solution X;

[0085] S2: adding a required amount of diisocyanate monomer to the reaction solution X, and adding a required amount of acidic substance to the system to obtain a reaction solution Y;

[0086] S3: heating the reaction solution Y to the desired reaction temperature and continuing the reaction to obtain the reaction solution Z;

[0087] S4: removing unreacted diisocyanate monomers in the reaction solution Z to obtain a polyisocyanate composition;

[0088] In a preferred embodiment, the diisocyanate monomer is selected from one or more of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate, preferably pentamethylene diisocyanate and / or hexamethylene diisocyanate.

[0089] Preferably, the trimerization catalyst comprises a quaternary ammonium base catalyst and / or a quaternary ammonium salt catalyst, preferably choline hydroxide, trimethylhydroxyethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, N,N,N-trimethylbenzylammonium hydroxide, tetraethylammonium formate, tetraethylammonium acetate, tetrabutylammonium decanoate, trimethylhydroxypropylammonium formate, trimethylhydroxypropylammonium acetate, trimethylhydroxypropylammonium decanoate, trimethylhydroxyethylammonium formate, or a combination of at least two thereof, and further preferably benzyltrimethylammonium hydroxide and / or tetrabutylammonium decanoate.

[0090] Preferably, the amount of the trimerization catalyst used is 20-500 ppm relative to the total mass of the diisocyanate monomer in step S1.

[0091] In some examples, an alcohol compound is added to the reaction system of step S1. There is no limit to the time of adding the alcohol. The alcohol compound can be added at any stage of step S1, such as before adding the trimerization catalyst, simultaneously with the trimerization catalyst, or during the trimerization reaction after the trimerization catalyst is added. Preferably, the amount of the alcohol compound added is 100-5000ppm of the total mass of the diisocyanate monomer in step S1. The alcohol compound is selected from one or more of aliphatic monohydric alcohols and aliphatic dihydric alcohols; wherein the monohydric alcohol can include one or more of ethanol, n-propanol, n-butanol, n-hexanol, isooctyl alcohol, etc.; the dihydric alcohol can include one or more of ethylene glycol, 1,3-butanediol, 1,4-hexanediol, 1,3-diethylhexanediol, etc.

[0092] Preferably, the reaction conversion rate in step S1 is 20-50%. The catalyst is poisoned by adding a terminator, and feasible terminators are, for example, di-n-butyl phosphate, diisooctyl phosphate, phosphoric acid, p-toluenesulfonic acid, etc. The method of selecting a suitable terminator to terminate the reaction according to the specific selection of the catalyst used is known, and is not intended to be any limitation of the present invention.

[0093] Preferably, in step S2, the mass of the added diisocyanate monomer is 5-20% of the total mass of the diisocyanate monomer in step S1.

[0094] Preferably, in step S2, the acidic substance added is any one or a combination of organic acid and inorganic acid, preferably one or a combination of phosphoric acid, acetic acid, p-toluenesulfonic acid, and diisooctyl phosphate. Preferably, relative to the total mass of the reaction liquid system after the diisocyanate monomer is added in step S2, the amount of the acidic substance added is 20-500 ppm.

[0095] Preferably, in step S1, the polymerization reaction temperature is 30-120°C; in step S3, the reaction temperature is 100-180°C, and the reaction time is, for example, 60-150 min.

[0096] Preferably, in step S4, unreacted diisocyanate monomers are removed by any one or more of the following methods: thin film evaporation, falling film evaporation, short path evaporation, vacuum distillation; preferably, unreacted monomers are removed by two-stage thin film evaporation, for example, thin film evaporation is performed at 120-180°C.

[0097] Preferably, the content of unreacted diisocyanate monomers in the polyisocyanate composition is controlled to be below 0.2 wt %.

[0098] In the above preparation method, by adjusting the conversion rate in step S1, the amount of the acidic substance added in step S2 and / or the reaction time in step S3, the values ​​of b / (a+c) and y / (x+z) of the prepared polyisocyanate composition can be adjusted, and a polyisocyanate composition product that meets the required requirements can be obtained.

[0099] The above preparation method is only an exemplary method for preparing the polyisocyanate composition of the present invention for reference. The method for preparing the polyisocyanate composition of the present invention is not limited thereto. Those skilled in the art can also prepare the polyisocyanate composition that meets the requirements of the present invention by other methods. For example, the polyisocyanate composition of the present invention can also be obtained by the following method:

[0100] The polyisocyanate composition meeting the requirements is obtained by mixing a commercially available uretdione polyisocyanate composition, a diisocyanate monomer, an isocyanurate polyisocyanate composition and a certain amount of an acidic substance in a certain proportion, heating for a certain period of time, and then removing the excess diisocyanate monomer. The polyisocyanate composition meeting the requirements can be obtained by adjusting the mixing ratio of each component, the amount of the acidic substance added, the heating temperature and / or the heating time.

[0101] Preferably, the mixing mass ratio of the diisocyanate monomer, the uretdione-based polyisocyanate composition, and the isocyanurate-based polyisocyanate composition is (0.1-2):1:1;

[0102] Preferably, the acidic substance is an inorganic acid and / or an organic acidic substance, such as one or more combinations of di-n-butyl phosphate, diisooctyl phosphate, diethyl phosphate, acetic acid, etc. Preferably, based on the total mass of the raw material, the amount of the acidic substance added is 20-1000ppm.

[0103] Preferably, after the acidic substance is added and mixed, the mixture is heated to 80-150° C., and the heating time is, for example, 30-150 min.

[0104] Unless otherwise specified, "%" in the present invention refers to mass percentage.

[0105] The present invention also provides a coating composition, wherein the coating composition comprises the polyisocyanate composition described above. The coating composition, for example, comprises the polyisocyanate composition provided by the present invention and a polyol, wherein the amounts of the polyisocyanate composition and a polyol are calculated according to the molar ratio of isocyanate groups to hydroxyl groups, for example, (1-1.5):1.

[0106] In the coating composition, the polyol may be any known auxiliary curing component, including but not limited to one or more of acrylic polyols, polyester polyols, etc. The acrylic polyol is obtained by, for example, polymerizing one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate; the polyester polyol is obtained by, for example, condensing one or more of succinic acid, adipic acid, sebacic acid, and maleic anhydride with one or more alcohols selected from ethylene glycol, propylene glycol, diethylene glycol, and neopentyl glycol.

[0107] In the coating composition, the number average molecular weight of the polyol is preferably 2000 or more and 8000 or less. When the molecular weight of the polyol is lower than 2000, the crosslinking degree is poor when it is applied to the coating composition. When the molecular weight of the polyol is higher than 8000, the compatibility of the paint film is poor when it is applied to the coating composition, further affecting the gloss and texture of the paint film. When the molecular weight of the polyol is 2000 or more and 8000 or less, it is beneficial to simultaneously ensure the excellent crosslinking degree and compatibility of the coating composition.

[0108] The present invention also provides the use of the polyisocyanate composition described above in improving the gloss, solvent resistance and appearance of a paint film; the appearance includes the sharpness and surface smoothness of the paint film.

[0109] The present invention is further described below by way of examples, but it should not be understood that the present invention is limited thereto.

[0110] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0111] <Information of main raw materials in Examples and Comparative Examples>

[0112] HDI: Hexamethylene diisocyanate, Covestro AG;

[0113] PDI: pentamethylene diisocyanate, Covestro AG;

[0114] N,N,N-trimethylbenzyl ammonium hydroxide, Aladdin reagent platform;

[0115] Isooctyl alcohol, Aladdin reagent platform;

[0116] p-Toluenesulfonic acid, Aladdin reagent platform;

[0117] Di-n-butyl phosphate, Aladdin reagent platform;

[0118] <Measurement of product viscosity>

[0119] The viscosity of the products in the examples and comparative examples was measured using a Brookfield RC / S rheometer, rotor model CC-40, constant temperature water bath, controlled temperature at 25±0.1°C, shear rate 25S -1 -250S -1 .

[0120] <Reaction conversion rate>

[0121] The reaction conversion rate refers to the mass ratio of the diisocyanate that has been reacted and converted based on the mass of the initial diisocyanate raw material. The diisocyanate monomer is quantified by liquid exclusion chromatography to monitor the reaction conversion rate.

[0122] The liquid exclusion chromatography instrument is Agilent 1260, the chromatographic columns are Pl1113-6520 and Pl113-6325, Agilent; mobile phase: tetrahydrofuran; flow rate: 1.0 mL / min; detection method: differential detector; sample concentration: 3 wt%; analysis time: 40 min, column temperature: 35°C.

[0123] <Measurement of polymer A, B, C contents and UV absorption peak height>

[0124] The contents of polymer A, polymer B and polymer C in the polyisocyanate composition and the height of the UV absorption peak were measured by gel permeation chromatography (GPC).

[0125] The mass contents of polymer A, polymer B and polymer C in the polyisocyanate composition are respectively denoted as a, b and c, and are measured by area normalization method using a differential detector; the heights of the UV absorption peaks of polymer A, polymer B and polymer C are respectively denoted as x, y and z, and are measured using a UV detector. In the following examples and comparative examples, polymer A is composed of polymers of structural formula (I) and / or structural formula (II), polymer B is composed of polymers of structural formula (III), structural formula (IV), structural formula (V) and / or structural formula (VI), and polymer C is composed of polymers of structural formula (VII), structural formula (VIII), structural formula (IX), structural formula (X) and / or structural formula (XI).

[0126] The liquid exclusion chromatography instrument is Agilent 1260, the chromatographic columns are Pl1113-6520 and Pl113-6325, Agilent; mobile phase: tetrahydrofuran; flow rate: 1.0 mL / min; detection method: UV detector (measurement wavelength is 254 nm); sample concentration: 3 wt%; analysis time: 40 min, column temperature: 35°C.

[0127] <Determination of free diisocyanate monomer content>

[0128] In the examples and comparative examples of the present invention, the residual monomer content in the reaction system was determined using an Agilent GC-7890B gas chromatograph manufactured by Agilent based on the method of GB / T18583-2008.

[0129] <NCO content (NCO%)>

[0130] NCO% content test, refer to standard GB / T 12009.4.

[0131] <Determination of the molar ratio of iminooxadiazinedione group, uretdione group and isocyanurate group>

[0132] The molar ratio d / m of the iminooxadiazinedione group to the isocyanurate group and the molar ratio e / m of the uretdione group to the isocyanurate group in the polyisocyanate composition of the present invention are quantitatively determined by the composition. 13 CNMR test is used to determine the specific test conditions.

[0133] 13 C-NMR equipment: AVANCE600 (Bruker); BBO probe (Bruker); sample concentration: 30wt%; resonance frequency: 150MHz; shift reference: 77.0ppm (CDCl3); pulse program: zgig30; spectrum width: 240ppm; spectrum center: 100ppm

[0134] Isocyanurate group: integrated value around 148.5 ppm / 3; iminooxadiazinedione group: integrated value around 145.5 ppm / 1; uretdione group: integrated value around 157.5 ppm / 2.

[0135] <Thermal stability test>

[0136] The thermal stability of the polyisocyanate composition was tested by the following method: 50 g of the polyisocyanate composition was packed into a 125 mL wide-mouth glass bottle and sealed with nitrogen, and then placed in a 50° C. oven for 60 days, and the content of free diisocyanate monomers in the polyisocyanate composition before and after storage was tested.

[0137] <Ethanol wiping resistance test of coating>

[0138] A coating was prepared by mixing a hydroxypropyl resin (AC1100B, Tongde resin) and a polyisocyanate composition, wherein the raw materials were added according to a molar ratio of isocyanate group to hydroxyl group of 1.1:1, the coating had a solid content of 40%, and the solvent was butyl acetate and xylene in a mass ratio of 1:1.

[0139] Ethanol wipe resistance test: After the paint film is scraped, bake it at 70℃ for 30 minutes. After leaving it for 24 hours, use a solvent resistance wiper to perform an ethanol wipe test and record the number of wipe resistance tests.

[0140] <Appearance and glossiness of coating film>

[0141] A hydroxypropyl resin (AC1100B, Tongde resin) and a polyisocyanate composition were mixed in a ratio of 1.0 in the molar ratio of NCO group to OH group of acrylic polyol (NCO / OH), and the solid content was adjusted to 55% by mass using "SOLVESSO#100" (trade name, aromatic solvent manufactured by Exxon) to prepare a coating composition. Then, the coating composition was applied to an ABS plate (acrylonitrile-butadiene-styrene resin; black, 150 mm×75 mm) by spraying in a dry film thickness of 50 μm. After baking at 60°C for 30 minutes, it was left to stand at 23°C and 50% humidity for 1 week to form a coating film on the ABS plate.

[0142] Appearance of the coating (sharpness and surface smoothness): measured along the long side direction of the ABS plate using a digital oscilloscope "Wave Scan DOI" (manufactured by BYKGardner). "Wave Scan DOI" is configured as follows: the point light source of the laser irradiates the laser light at an angle of 60° from the vertical line relative to the surface of the film, and the detector receives the reflected light at the same angle on the opposite side relative to the vertical line. The device moves and scans the point light source of the laser on the surface of the film, thereby measuring the brightness of the reflected light point by point at a specified interval, and can detect the optical profile of the film surface. The detected optical profile is spectrally analyzed by a frequency filter, and the structure of the surface can be analyzed. Among them, the values ​​of the Wb area (wavelength 0.3-1.0 mm) and the Wc area (wavelength 1.0-3.0 mm) of the coating are used for evaluation. The measured value is the arithmetic mean of the three measured values. Wb and Wc are both indicators of the appearance of the coating, Wb is an indicator of the sharpness of the coating, and Wc is an indicator of smoothness. The smaller the value, the better it is judged.

[0143] Glossiness of coating film: The 60° glossiness of the coating film was measured using "UGV-6P" (manufactured by Suga Test Instruments Co., Ltd.).

[0144] Examples 1-7 and Comparative Examples 1-4

[0145] Examples 1-7 and Comparative Examples 1-4 were prepared with reference to the following preparation steps. The selection of diisocyanate monomers and some reaction parameters in each example and comparative example are shown in Table 1. The physical properties and application evaluation data of the polyisocyanate compositions prepared in each example and comparative example are shown in Table 1 and Table 2.

[0146] The preparation steps of the polyisocyanate composition are as follows:

[0147] Step S1: 1000 g of diisocyanate monomer was added to a 2L four-necked flask, the temperature was raised to 65° C. under nitrogen protection, 2 g of 5% mass concentration of N,N,N-trimethylbenzyl ammonium hydroxide isooctyl alcohol solution was added under stirring, the reaction temperature was controlled to be 65-70° C., and when the reaction reached a certain conversion rate, 0.16 g of di-n-butyl phosphate was added to terminate the reaction to obtain a reaction solution X.

[0148] Step S2: 1000 g of reaction solution X and 100 g of diisocyanate monomer are mixed, and then a certain amount of acidic substance p-toluenesulfonic acid is added to the mixed system, and the mixture is mixed evenly to obtain reaction solution Y;

[0149] Step S3: reacting the reaction solution Y at 150° C. for a certain period of time under nitrogen protection, and then lowering the reaction temperature to room temperature to obtain a reaction solution Z.

[0150] Step S4: using a thin film evaporator, distill the reaction solution Z twice at 150° C. and 30 Pa to obtain a polyisocyanate composition having a diisocyanate monomer content of less than 0.2 wt %.

[0151] Example 8

[0152] 100 g of commercially available HDI, 500 g of commercially available N3400 (uretdione structure molar content of about 35%, Covestro) and 500 g of commercially available N3300 (isocyanurate structure molar content of about 98%, Covestro) were mixed, and 200 ppm of di-n-butyl phosphate was added. The mixture was then reacted at 150 ° C for 90 min under nitrogen protection, and then quickly cooled to room temperature. The excess HDI was removed by thin film evaporation to obtain the target product.

[0153] Example 9

[0154] 100 g of commercially available HDI, 500 g of commercially available N3400 (with a uretdione structure molar content of about 35%) and 500 g of commercially available N3300 (with an isocyanurate structure molar content of about 98%) were mixed, and then 500 ppm of di-n-butyl phosphate was added. The mixture was then reacted at 150° C. for 120 min under nitrogen protection, and then rapidly cooled to room temperature. Excess HDI was removed by thin film evaporation to obtain the target product.

[0155] Table 1. Process parameters and physical property data of examples / comparative examples

[0156]

[0157]

[0158] Note: "S2 acidic substance addition amount" in Table 1 refers to the amount of the acidic substance added relative to the total mass of the reaction liquid system after the diisocyanate monomer is added in step S2.

[0159] Table 2. Viscosity, thermal stability and application test data of polyisocyanate compositions of Examples / Comparative Examples

[0160]

[0161] It can be seen from the experimental results of the embodiments and comparative examples that when the contents a, b, c of the dipolymer A, trimolecular polymer B and tetramolecular polymer C derived from the diisocyanate monomer in the polyisocyanate composition satisfy 10≤b / (a+c)≤150; and the peak heights x, y, z of the UV absorption peaks of polymer A, polymer B and polymer C in the measurement spectrum of the polyisocyanate composition obtained by gel permeation chromatography (GPC) of the polyisocyanate composition satisfy 0.1≤y / (x+z)≤10, the composition can take into account lower viscosity (for example, ≤4000mPa.s), good crosslinking properties and good thermal stability, and is used in a coating composition. The resulting coating can take into account excellent coating appearance, glossiness and ethanol wiping resistance (for example, ethanol wiping resistance ≥270 times), and the comprehensive performance is significantly improved.

[0162] In Comparative Examples 1 to 4, low viscosity, good crosslinking and thermal stability cannot be well balanced. In Comparative Example 3, the composition has a significantly high viscosity, and when used as a coating, a large amount of solvent is required for dilution, and the volatilization of the solvent is detrimental to human health and the environment.

[0163] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A polyisocyanate composition, comprising isocyanurate groups, characterized in that: The polyisocyanate composition contains polymer A, polymer B and polymer C, and the mass contents of polymer A, polymer B and polymer C in the polyisocyanate composition are a, b and c respectively, and satisfy 10≤b / (a+c)≤150; The polyisocyanate composition has a UV absorption peak in a measurement spectrum obtained by gel permeation chromatography, and the heights of the UV absorption peaks of polymer A, polymer B and polymer C are x, y, and z, respectively, and satisfy 0.1≤y / (x+z)≤10; The polymer A is a polymer of two monomers, wherein the monomers in the two monomers are diisocyanate and an optional alcohol compound; The polymer B is a polymer of three monomers, and the monomers in the three monomers are diisocyanate and an optional alcohol compound; The polymer C is a polymer of four molecules of monomers, and the monomers in the four molecules of monomers are diisocyanate and an optional alcohol compound.

2. The polyisocyanate composition according to claim 1, characterized in that The polymer A mainly comprises one or more of a uretdione dimer formed by the reaction of two molecules of diisocyanate, and a carbamate formed by the reaction of one molecule of diisocyanate and one molecule of an alcohol compound; And / or, the polymer B mainly comprises one or more of a trimer formed by the reaction of three molecules of diisocyanate, and an allophanate formed by the reaction of two molecules of diisocyanate and one molecule of an alcohol compound; the trimer formed by the reaction of three molecules of diisocyanate comprises one or more of an isocyanurate trimer, an iminooxadiazinedione trimer, and a uretdione trimer; And / or, the polymer C mainly comprises one or more of isocyanurate-uretdione-based tetramer, iminooxadiazinedione-uretdione-based tetramer, and uretdione-based tetramer.

3. The polyisocyanate composition according to claim 2, characterized in that In the polymer A, the uretdione dimer and the carbamate have the following structural formulas (I) and (II) respectively: In the structural formula (I) and the structural formula (II), each R1, R2, and R3 is independently a straight-chain alkyl group, a branched-chain alkyl group, or a cycloalkyl group, and the number of carbon atoms is independently 3-14; In the polymer B, the isocyanurate trimer, the iminooxadiazinedione trimer, the allophanate and the uretdione trimer have the following structural formulas (III), (IV), (V) and (VI) respectively: In the structural formula (III), structural formula (IV), structural formula (V) and structural formula (VI), each R4, each R5, each R6, R7, and each R8 are independently a linear alkyl group, a branched alkyl group or a cycloalkyl group, and the number of carbon atoms is independently 3-14; In the polymer C, the isocyanurate-uretdione tetramer has the following structural formula (VII), the iminooxadiazinedione-uretdione tetramer is one or more compounds having the following structural formulas (VIII), (IX), and (X), and the uretdione tetramer has the following structural formula (XI): In the structural formula (VII), structural formula (VIII), structural formula (IX), structural formula (X) and structural formula (XI), each R9, each R 10 , each R 11 , each R 12 , each R 13 Each is independently a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, and each has independently 3 to 14 carbon atoms.

4. The polyisocyanate composition according to any one of claims 1 to 3, characterized in that The alcohol compound is introduced as a separate reaction raw material and / or as a solvent when preparing the polyisocyanate composition; The alcohol compound is selected from one or more of aliphatic monohydric alcohols and aliphatic dihydric alcohols.

5. The polyisocyanate composition according to any one of claims 1 to 4, characterized in that The content of the polymer B in the polyisocyanate composition is 25-75 wt %.

6. The polyisocyanate composition according to any one of claims 1 to 5, characterized in that: The viscosity of the polyisocyanate composition measured at 25° C. is 100-4000 mPa·s.

7. The polyisocyanate composition according to any one of claims 1 to 6, characterized in that: The polyisocyanate composition contains iminooxadiazinedione groups, and the ratio of the molar amount d of the iminooxadiazinedione groups to the molar amount m of the isocyanurate groups is 0.01-0.15; And / or, the polyisocyanate composition contains uretdione groups, and the ratio of the molar amount e of the uretdione groups to the molar amount m of the isocyanurate groups is 0.01-0.

05.

8. The polyisocyanate composition according to any one of claims 1 to 7, characterized in that: The polyisocyanate composition is derived from an aliphatic diisocyanate and / or an alicyclic diisocyanate.

9. A coating composition, characterized in that: The coating composition comprises the polyisocyanate composition according to any one of claims 1 to 8.

10. Use of the polyisocyanate composition according to any one of claims 1 to 8 for improving the gloss, alcohol resistance and / or appearance of a paint film; The appearance includes the sharpness and surface smoothness of the paint film.

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