A kind of polyisocyanate composition with high reactivity and preparation method

Abstract

The present invention provides a highly reactive polyisocyanate composition and a preparation method thereof. The polyisocyanate composition has the following characteristics: the polyisocyanate composition comprises isocyanurate formed by the trimerization reaction of xylylene diisocyanate and aliphatic diisocyanate, and the composition comprises three isocyanurate mononuclear bodies of structures (I), (II) and (III) at the same time, and the mass proportions of the three mononuclear bodies, based on the total mass of the isocyanate composition, satisfy the following relationship: (II) < (I) < (III). The polyisocyanate composition prepared by the present invention has the characteristics of high reactivity, high gloss of the paint film after curing, and simple manufacturing process, and is particularly suitable for fields such as automotive repair paints that have certain requirements on construction period and weather resistance.

Description

Technical Field

[0001] The invention belongs to the field of polymer coatings, and in particular relates to a highly reactive polyisocyanate composition and a preparation method thereof. Background Art

[0002] The polyurethane coating formed by the reaction of isocyanate curing agent and polyol has good wear resistance, toughness and easy processing, so it is widely used in various fields such as automotive coatings, home appliances, toys, leather interiors, etc. The coating prepared by the traditional aromatic isocyanate series has high reactivity during the curing process, but with the extension of use time, the product is prone to yellowing or powdering to varying degrees. The aliphatic isocyanate series composition obviously has better yellowing resistance, and the product is more used in fields with high weather resistance requirements, but the reactivity of aliphatic isocyanates is poor, resulting in a long drying time for the product, which affects the construction efficiency and progress.

[0003] In order to ensure that downstream customers can achieve rapid curing during application, CN101619194 improves the reaction rate of hexamethylene isocyanurate and hydroxy acrylic resin by adding high hydroxyl value reactive cellulose acetate butyrate and organic tin catalyst for polyurethane, shortens the product drying time, and has a certain effect, but the amount of cellulose acetate butyrate and tin catalyst is difficult to balance between the mechanical stability and quick drying of the product, and the application field is limited. CN101812261 uses 80% of 1,6-hexamethylene diisocyanate trimer and 20% of isophorone diisocyanate or quick-drying 1,6-hexamethylene diisocyanate trimer for physical blending, and then uses it as an isocyanate curing agent to increase the drying speed of the product. In essence, physical blending is used as a method to improve the quick drying of the product. This method requires pre-mixing treatment first, and the reaction activity that can be improved by isophorone diisocyanate or quick-drying 1,6-hexamethylene diisocyanate trimer is limited. DE19752691 uses a cold-blended mixture of polyisocyanates formed by isophorone diisocyanate and polyisocyanates formed by pentamethylene diisocyanate to improve certain properties of polyisocyanates. This is also a physical modification, and it is difficult to achieve high glossiness produced by chemical bonding. US6472493B1 prepares a quick-drying curing agent, which mainly shortens its construction time and service life by adding amine catalysts and carboxylic acid catalysts, resulting in the paint film being prone to yellowing, scratches, and poor adhesion during later use.

[0004] Therefore, developing highly active isocyanate curing agents with excellent performance has become an urgent problem to be solved. Summary of the invention

[0005] To this end, the purpose of the present invention is to overcome the defects of the prior art and provide a polyisocyanate composition and a preparation method thereof, which not only improves the reactivity of the aliphatic isocyanate curing agent, shortens the construction period at the application level, but also significantly improves the adhesion of the formed paint film to the plastic substrate (PMMA) or metal substrate of the automobile.

[0006] The present invention is achieved through the following technical solutions: In the first aspect, the present invention provides a highly reactive polyisocyanate composition.

[0007] The polyisocyanate composition comprises isocyanurate formed by the trimerization reaction of xylylene diisocyanate and aliphatic diisocyanate, and the composition comprises three isocyanurate mononuclear bodies of structures (I), (II) and (III), and the molar ratios of the three mononuclear bodies satisfy the following relationship: (II)<(I)<(III).

[0008]

[0009] Wherein, R1 is a residual structure after removing the isocyanate group from hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate or bis(isocyanatomethyl)norbornane.

[0010] The polyisocyanate composition of the present invention adopts aliphatic diisocyanate and xylylene diisocyanate structures, both of which have good weather resistance, and xylylene has two NCO groups with high reactivity. Through the unique isocyanurate stepwise copolymerization process, on the one hand, the modified aliphatic diisocyanate trimer can have free NCO groups with higher reactivity, and the drying speed is significantly improved. On the other hand, the inventor surprisingly found that due to the increase in the asymmetric structure of the modified isocyanurate ring formed by xylylene diisocyanate and aliphatic diisocyanate, the curing agent is not easy to cause symmetrical shrinkage when cross-linking and curing on the surface of the substrate, so that its adhesion on the surface of the metal substrate or the plastic substrate is significantly improved.

[0011] Furthermore, the ratio of the modified isocyanurate mononuclear structure (II) to the structure (I) in the polyisocyanate composition is between 5% and 30%, preferably between 5% and 15%.

[0012] The inventor unexpectedly discovered that by controlling the ratio of isocyanurate mononuclear structure (II) / structure (I), the depth of polymerization of xylylene diisocyanate and aliphatic diisocyanate can be guaranteed. By controlling the ratio of isocyanurate mononuclear structure (II) / structure (I) to be less than 30%, it is possible to avoid excessive self-polymerization of high-content xylylene diisocyanate to form an unstable mixture. By controlling the ratio of isocyanurate mononuclear structure (II) / structure (I) to be greater than 5%, a short drying time of the final isocyanate composition can be guaranteed. More importantly, it was found that the two are fully cross-polymerized and the structural ratio is guaranteed to be within 5%-30%, so that the final polyisocyanate composition can better maintain the highly reactive isocyanate groups and adhesion to the substrate.

[0013] Furthermore, in the polyisocyanate composition, based on the total mass of the isocyanate composition being 100%, the sum of the contents of free xylylene diisocyanate and aliphatic diisocyanate monomers is less than 0.5%.

[0014] Furthermore, in the polyisocyanate composition, the xylylene isocyanate is composed of 1,3-xylylene diisocyanate isomers in consideration of the difficulty of obtaining industrial raw materials and production.

[0015] Furthermore, the aliphatic diisocyanate is selected from one or more of hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and bis(isocyanatomethyl)norbornane, preferably hexamethylene diisocyanate and / or 1,5-pentamethylene diisocyanate.

[0016] In a second aspect, the present invention further provides a method for preparing the above-mentioned polyisocyanate composition, comprising the following steps:

[0017] S1: adding aliphatic diisocyanate into a reaction vessel and heating it, adding a catalyst, adding xylylene diisocyanate, and performing a continuous copolymerization reaction;

[0018] S2: After the addition of xylylene diisocyanate is completed, the reaction is continued to reach the target polymerization conversion rate of the aliphatic diisocyanate, and a terminator is added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted aliphatic diisocyanate and xylylene diisocyanate are removed to obtain a polyisocyanate composition.

[0019] Furthermore, in S1, the cumulative added mass content of xylylene diisocyanate is 4%-20% based on the total mass of xylylene diisocyanate and aliphatic diisocyanate.

[0020] Furthermore, the xylylene diisocyanate in S1 is added dropwise; preferably, the dropping rate of the xylylene diisocyanate is not particularly limited, and the dropping time is preferably controlled to be 50-100 minutes.

[0021] Furthermore, the catalyst described in S1 is not particularly limited, and is preferably a catalyst that can simultaneously catalyze xylene diisocyanate and aliphatic diisocyanate, more preferably one or more of trimethylhydroxyethylammonium, triethylhydroxypropylammonium, tetramethylammonium acetate, tetrabutylammonium acetate, tetramethylammonium propionate, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriphenylphosphine chloride, and 2,4,6-tris(dimethylaminomethyl)phenol.

[0022] Furthermore, S1 is performed under an inert gas atmosphere.

[0023] Further, the temperature in S1 is raised to 40-120°C.

[0024] Furthermore, when the polymerization conversion rate of the aliphatic diisocyanate in S2 reaches 35-65%, preferably 40-50%, a terminator is added to terminate the reaction.

[0025] Furthermore, unreacted aliphatic diisocyanate and xylylene diisocyanate are removed by distillation in S2.

[0026] Furthermore, the terminator is an acid compound, preferably one or more of dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, 2-ethylhexyl phosphate, phosphoric acid, hydrochloric acid, benzenesulfonic acid, p-toluenesulfonic acid, benzoyl chloride, and acetyl chloride.

[0027] Another object of the present invention is to provide a polyurethane resin.

[0028] The polyurethane resin is prepared by mixing a polyisocyanate composition as an isocyanate component and a hydroxyl-containing acrylic resin as a polyol component according to a molar equivalent of NCO to OH value of 1.0-1.1. Whether to add an inert solvent for dilution can be selected according to actual working conditions.

[0029] Furthermore, the inert solvent can be selected from acetone, ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, xylene, and S100 solvent oil, preferably at least two of ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate.

[0030] Another object of the present invention is to provide a polyurethane composite material.

[0031] The polyurethane composite material is obtained by coating polyurethane resin on the surface of a metal substrate and / or a plastic. The metal substrate is preferably selected from a Q235 steel plate substrate, and the plastic substrate is selected from a polymethyl methacrylate plate.

[0032] The technical solution provided by the present invention has the following beneficial effects:

[0033] In the process of preparing modified aliphatic diisocyanate isocyanurate, by continuously dropping xylylene diisocyanate into aliphatic diisocyanate for copolymerization, the content ratio of the modified isocyanurate mononuclear bodies (I) and (II) in the reaction system is further controlled to finally obtain a modified isocyanate composition reaction liquid, and the unreacted aliphatic diisocyanate and xylylene diisocyanate are further removed to obtain an isocyanate composition. Compared with the prior art, the composition not only improves the reaction activity of the product, but also does not lead to the formation of an unstable system due to the high polymerization of xylylene diisocyanate added at one time. In addition, it is unexpectedly found that the paint film formed by the modified isocyanate composition has significantly improved adhesion to a metal substrate or a plastic substrate. Therefore, it is particularly suitable for the field of automobile repair paint. DETAILED DESCRIPTION

[0034] In order to better understand the technical solution of the present invention, the content of the present invention is further described below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0035] Some of the raw materials and their sources used in the following examples and comparative examples of the present invention are as follows:

[0036] Xylylene diisocyanate (XDI), specifically 1,3-xylylene diisocyanate isomer, was purchased from Wanhua Chemical Group Co., Ltd.;

[0037] Hexamethylene diisocyanate (HDI) was purchased from Wanhua Chemical Group Co., Ltd.

[0038] Isophorone diisocyanate (IPDI) was purchased from Wanhua Chemical Group Co., Ltd.

[0039] T 12 , dibutyltin dilaurate, a commonly used drier for polyurethane resin, was purchased from Nanjing Advant Co., Ltd.;

[0040] Tetrabutylammonium hydroxide, isocyanurate catalyst, purchased from Evonik Chemical Industries, Ltd.;

[0041] Tetramethylammonium hydroxide, isocyanurate catalyst, purchased from Evonik Chemical Industries, Ltd.;

[0042] Benzyltrimethylammonium hydroxide, isocyanurate catalyst, was purchased from Xindian Chemical Co., Ltd.;

[0043] Dioctyl phosphate, isocyanurate terminator, were purchased from Tianjin Yongda Chemical Reagent Co., Ltd.;

[0044] Dimethyl phosphate, isocyanurate terminator, was purchased from Tianjin Yongda Chemical Reagent Co., Ltd.;

[0045] Polymethyl methacrylate (PMMA) sheet, 0.5 mm thick, purchased from Biugeda Instruments Co., Ltd.;

[0046] Q235 substrate steel plate, 3 mm thick, purchased from Biugeda Instruments Co., Ltd.;

[0047] Ethyl acetate, purity 99.8%, used as polyurethane resin solvent, purchased from Aladdin Reagent Co., Ltd.;

[0048] Butyl acetate, purity 99.8%, used as polyurethane resin solvent, purchased from Aladdin Reagent Co., Ltd.;

[0049] Malonate methyl ether acetate, purity 99.8%, used as polyurethane resin solvent, purchased from Aladdin Reagent Co., Ltd.;

[0050] Unless otherwise specified, the contents in the present invention are all by mass.

[0051] In the following embodiments and comparative examples of the present invention, the relevant testing methods are as follows:

[0052] (1) NCO content test is carried out in accordance with GB / T 12009.4;

[0053] (2) The test method for the mononuclear structure of isocyanurate is as follows:

[0054] The 13C nuclear magnetic resonance spectrum was measured using AVANCE400 manufactured by Bruker Biospin, deuterated chloroform CDCl3 as solvent, at a sample (produced isocyanurate product) mass concentration of 60%, 100 MHz, and scanning overnight.

[0055] It should be noted that in the above measurement, the following characteristic signals were integrated, and the mass proportions of the structures (I), (II) and (III) were calculated from the values ​​thereof.

[0056] (a) Formula I structure: δ around 148.3 ppm

[0057] (b) Formula II structure: around δ150.7ppm

[0058] (c) Formula III structure: δ around 148.6 ppm

[0059] (d) Mass ratio of (Formula II) / (Formula I): (Formula II) / (Formula I) = (signal area of ​​the structure of Formula II) / (signal area of ​​the structure of Formula I).

[0060] (3) The sum of the content of free xylylene diisocyanate and aliphatic diisocyanate monomers was tested by establishing an external standard curve using high performance liquid chromatography (HPLC). The key parameters can be referred to as follows:

[0061] Chromatographic column: Waters XSelect HSS T3 5um 4.6*250mm;

[0062] Automatic sample injector: SIL-20A

[0063] Column temperature: 40°C

[0064] Injection volume: 10 μL

[0065] Detection wavelength: 281nm

[0066] Derivatization reagent: 4% 1-methoxyphenylpiperazine-acetonitrile solution.

[0067] The concentrations of xylylene diisocyanate and aliphatic diisocyanate are calculated based on their respective peak areas and external standard curves, and the sum of the two concentrations is taken as the sum of the free xylylene diisocyanate and aliphatic diisocyanate monomer contents in the polyisocyanate composition.

[0068] Preparation of polyisocyanate composition:

[0069] [Example 1]

[0070] The preparation method of the polyisocyanate composition comprises the following steps: under a nitrogen atmosphere, 1000 g of 1,6-hexamethylene diisocyanate is first added into a reaction container and the temperature is raised to 60° C., and then 0.18 g of tetrabutylammonium hydroxide catalyst is added, and at the same time, xylene diisocyanate is added dropwise by a continuous dropwise feeding method, and a continuous copolymerization reaction is carried out under the action of the catalyst, and the continuous cumulative amount of xylene diisocyanate is controlled to be 250 g for 80 minutes, and then the dropwise addition is stopped, and the reaction rate is continued to be maintained until the polymerization conversion rate of 1,6-hexamethylene diisocyanate reaches 65%, and then 0.14 g of dioctyl phosphate terminator is added to terminate the reaction. , an isocyanate mixture solution is obtained, and unreacted 1,6-hexamethylene diisocyanate and xylylene diisocyanate are further removed by two-stage thin film evaporation. The conditions for the first stage thin film evaporation are: temperature 135°C, vacuum degree 10Pa; the conditions for the second stage thin film evaporation are: temperature 145°C, vacuum degree 10Pa, to obtain a polyisocyanate composition 1#. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition is 21.0%, and the sum of the free 1,6-hexamethylene diisocyanate and hydrogenated xylylene diisocyanate monomer contents is 0.42%.

[0071] [Example 2]

[0072] The preparation method of the polyisocyanate composition comprises the following steps: under a nitrogen atmosphere, 1000 g of 1,6-hexamethylene diisocyanate is first added into a reaction container and the temperature is raised to 60° C., and then 0.17 g of tetrabutylammonium hydroxide catalyst is added, and at the same time, xylene diisocyanate is added dropwise by a continuous dropwise feeding method, and a continuous copolymerization reaction is carried out under the action of the catalyst, and the continuous cumulative amount of xylene diisocyanate is controlled to be 150 g for 60 minutes, and then the dropwise addition is stopped, and the reaction rate is continued to be maintained until the polymerization conversion rate of 1,6-hexamethylene diisocyanate reaches 60%, and then 0.12 g of dioctyl phosphate terminator is added to terminate the reaction. , an isocyanate mixture solution is obtained, and unreacted 1,6-hexamethylene diisocyanate and xylylene diisocyanate are further removed by two-stage thin film evaporation. The conditions for the first stage thin film evaporation are: temperature 140°C, vacuum degree 10Pa; the conditions for the second stage thin film evaporation are: temperature 150°C, vacuum degree 10Pa, to obtain a polyisocyanate composition 2#. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition is 21.2%, and the sum of the free 1,6-hexamethylene diisocyanate and hydrogenated xylylene diisocyanate monomer contents is 0.38%.

[0073] [Example 3]

[0074] The preparation method of the polyisocyanate composition comprises the following steps: under a nitrogen atmosphere, 1000 g of 1,6-hexamethylene diisocyanate is first added into a reaction container and the temperature is raised to 90° C., and then 0.15 g of benzyltrimethylammonium hydroxide catalyst is added, and at the same time, xylene diisocyanate is added dropwise by a continuous dropwise feeding method, and a continuous copolymerization reaction is carried out under the action of the catalyst, and the continuous cumulative amount of xylene diisocyanate is controlled to be 50 g for 50 minutes, and then the dropwise addition is stopped, and the reaction rate is continued to be maintained until the polymerization conversion rate of 1,6-hexamethylene diisocyanate reaches 50, and then 0.11 g of dioctyl phosphate terminator is added to terminate the reaction. , an isocyanate mixture solution is obtained, and unreacted 1,6-hexamethylene diisocyanate and xylylene diisocyanate are further removed by two-stage thin film evaporation. The conditions for the first stage thin film evaporation are: temperature 145°C, vacuum degree 10Pa; the conditions for the second stage thin film evaporation are: temperature 155°C, vacuum degree 20Pa, to obtain a polyisocyanate composition 3#. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition is 21.5%, and the sum of the free 1,6-hexamethylene diisocyanate and hydrogenated xylylene diisocyanate monomer contents is 0.41%.

[0075] [Example 4]

[0076] The preparation method of the polyisocyanate composition comprises the following steps: under a nitrogen atmosphere, 1000 g of isophorone diisocyanate is first added into a reaction container and the temperature is raised to 120° C., 0.18 g of tetramethylammonium hydroxide catalyst is then added, and at the same time, xylylene diisocyanate is added dropwise by a continuous dropwise feeding method, and a continuous copolymerization reaction is carried out under the action of the catalyst, the continuous addition of xylylene diisocyanate is controlled to be 150 g for 100 minutes, and then the dropwise addition is stopped, and the reaction rate is continued to be maintained until the polymerization conversion rate of isophorone diisocyanate reaches 40%, and 0.14 g of dimethyl phosphate terminator is added to terminate the reaction. The isocyanate mixture solution was obtained, and the unreacted isophorone diisocyanate and xylylene diisocyanate were further removed by two-stage thin film evaporation. The conditions of the first stage thin film evaporation were: temperature 140° C. and vacuum degree 50 Pa; the conditions of the second stage thin film evaporation were: temperature 150° C. and vacuum degree 20 Pa, so as to obtain a polyisocyanate composition 4#. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition was 18.5%, and the sum of the free isophorone diisocyanate and hydrogenated xylylene diisocyanate monomer contents was 0.35%.

[0077] [Comparative Example 1]

[0078] Compared with Example 1, the difference is that the amount of xylene diisocyanate added is 0 g, and polyisocyanate composition 5# is obtained. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition is 21.7%, and the free 1,6-hexamethylene diisocyanate content is 0.37%.

[0079] [Comparative Example 2]

[0080] Compared with Example 1, the difference is that the mass of the added xylene diisocyanate is 460g, and the polyisocyanate composition 6# is obtained. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition is 20.5%, and the sum of the free 1,6-hexylene diisocyanate and hydrogenated xylene diisocyanate monomer contents is 0.39%.

[0081] [Comparative Example 3]

[0082] The preparation method of the polyisocyanate composition of this embodiment comprises the following steps: under an inert gas atmosphere, 1000 g of 1,6-hexamethylene diisocyanate is first added into a reaction container and the temperature is raised to 60° C., and then 0.18 g of tetrabutylammonium hydroxide catalyst is added, and at the same time, xylene diisocyanate is added dropwise by continuous dropwise feeding, and a continuous copolymerization reaction is carried out under the action of the catalyst, and the continuous cumulative amount of xylene diisocyanate is controlled to be 800 g for 100 minutes, and then the dropwise addition is stopped, and the reaction rate is continued to be maintained until the polymerization conversion rate of 1,6-hexamethylene diisocyanate reaches 65%, and then 0.14 g of dioctyl phosphate terminator is added. The reaction was stopped to obtain an isocyanate mixture solution, and unreacted 1,6-hexamethylene diisocyanate and xylylene diisocyanate were further removed by two-stage thin film evaporation. The conditions for the first stage thin film evaporation were: temperature 140°C, vacuum degree 40Pa; the conditions for the second stage thin film evaporation were: temperature 150°C, vacuum degree 30Pa, to obtain a polyisocyanate composition 7#. After analysis, based on the total mass of the isocyanate composition as 100%, the NCO content of the polyisocyanate composition was 19.9%, and the sum of the free 1,6-hexamethylene diisocyanate and hydrogenated xylylene diisocyanate monomer contents was 0.36%.

[0083] The polyisocyanate compositions prepared in the examples and comparative examples were analyzed for the content relationship of structure (I), structure (II) and structure (III). The analysis results are shown in Table 1:

[0084] Table 1 Analysis results of polyisocyanate composition

[0085] project Formula (III) percentage / % Formula (II) percentage / % Formula (I) percentage / % Structural Relationship Ratio of formula (II) / (I) Example 1 31.5 4.1 9.7 (II)<(I)<(III) 28％ Example 2 34.3 2.0 7.8 (II)<(I)<(III) 19％ Example 3 39.5 0.5 5.9 (II)<(I)<(III) 8％ Example 4 31.2 1.4 7.4 (II)<(I)<(III) 15％ Comparative Example 1 48.1 0 0 —— 0％ Comparative Example 2 18.2 14.0 12.9 (I)<(II)<(III) 52％ Comparative Example 3 13.0 20.8 11.2 (III)<(I)<(II) 65％

[0086] Preparation and application examples of polyisocyanate compositions:

[0087] The above-mentioned polyisocyanate composition 1-7# is used as the isocyanate component, and a hydroxyl-containing acrylic resin (produced by Tongde Resin, trade name: AC1260) is used as the polyol component, and they are mixed in a ratio of isocyanate group / hydroxyl group molar ratio (NCO / OH) of 1.05, and diluted with a diluent (a mixed component of ethyl acetate / propylene glycol methyl ether acetate / butyl acetate mixed in a weight ratio of 1:1:1), the coating composition is diluted to 50wt%, and stirred at 23°C for 5 minutes and ultrasonically treated for 5 minutes to obtain a defoamed polyurethane resin coating solution.

[0088] The polyurethane resin coating solution obtained by the above method was applied to a steel plate (using Q235 model) and a polymethacrylate (PMMA) plate in a manner of a dry film thickness of 40 μm. Next, it was dried at 23°C for 2 hours, and then heat-treated at 80°C for 30 minutes. Then, it was aged for 7 days at 23°C and a relative humidity of 55% for use.

[0089] (1) Dry to touch time

[0090] The coating solution was applied to a glass plate using an applicator to a thickness of 100 μm (thickness before drying), and the time until the surface was no longer sticky when touched was measured at 23° C. and 30% relative humidity after coating.

[0091] (2) Curing and drying time

[0092] The coating solution was applied to a glass plate using an applicator to a thickness of 100 μm (thickness before drying), and the time after coating was measured at 23° C. and 30% relative humidity until no fingerprints were left when strongly pressed with a finger.

[0093] (3) Adhesion level

[0094] The adhesion of the coated samples based on the steel plate metal substrate (type Q235) and the plastic substrate (PMMA) was tested according to GB / T9286-1998 "Cross-cut test of paint and varnish film".

[0095] The polyisocyanate compositions prepared in each embodiment and comparative example were tested for application performance indicators according to the description of the application examples. The test results are shown in Table 2:

[0096] Table 2 Application performance indexes of polyisocyanate composition

[0097] raw material Touch drying time / second Curing drying time / min Adhesion / Metal Base Adhesion / Plastic Base Example 1 113 103 0 1 Example 2 138 126 1 2 Example 3 157 135 1 2 Example 4 121 112 1 2 Comparative Example 1 242 221 3 4 Comparative Example 2 100 93 4 5 Comparative Example 3 85 80 4 5

[0098] As can be seen from Table 1 and Table 2, the acrylate polyurethane resins prepared in Examples 1-4 all show excellent performance in terms of dry-to-touch time, curing drying time, and adhesion, and are particularly suitable for quick-drying fields such as automotive repair paints; while the acrylate polyurethane resin samples prepared in Comparative Examples 1-3 obviously have some poor indicators and lack comprehensive performance, making it difficult to meet actual needs. Obviously, the above embodiments are only examples for clear explanation, and are not limitations on the implementation methods. For ordinary technicians in the field, other different forms of changes or modifications can be made on the basis of 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 scope of protection of the invention.

Claims

1. A highly reactive polyisocyanate composition, characterized in that: The polyisocyanate composition comprises isocyanurate formed by the trimerization reaction of xylylene diisocyanate and aliphatic diisocyanate, and the composition comprises three isocyanurate mononuclear bodies of structures (I), (II) and (III), and the mass proportions of the three mononuclear bodies, based on the total mass of the isocyanate composition, satisfy the following relationship: (II)<(I)<(III), Wherein, R1 is a residual structure after removing the isocyanate group from one or more of 1,6-hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and bis(isocyanatomethyl)norbornane; The mass ratio of isocyanurate mononuclear structure (II) / structure (I) is in the range of 5%-30%.

2. The polyisocyanate composition according to claim 1, characterized in that The mass ratio of isocyanurate mononuclear structure (II) / structure (I) is in the range of 5%-15%.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that Based on the total mass of the isocyanate composition being 100%, the sum of the contents of free xylylene diisocyanate and aliphatic diisocyanate monomers is less than 0.5%.

4. The polyisocyanate composition according to claim 1, characterized in that Xylylene diisocyanate consists of 1,3-xylylene diisocyanate isomers.

5. The polyisocyanate composition according to claim 1, characterized in that The aliphatic diisocyanate is selected from one or more of hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and bis(isocyanatomethyl)norbornane.

6. The polyisocyanate composition according to claim 5, characterized in that The aliphatic diisocyanate is selected from hexamethylene diisocyanate and / or 1,5-pentamethylene diisocyanate.

7. A method for preparing the polyisocyanate composition according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1: adding aliphatic diisocyanate into a reaction vessel and heating it, adding a catalyst, adding xylylene diisocyanate, and performing a continuous copolymerization reaction; S2: After the addition of xylylene diisocyanate is completed, the reaction is continued to reach the target polymerization conversion rate of the aliphatic diisocyanate, and a terminator is added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted aliphatic diisocyanate and xylylene diisocyanate are removed to obtain a polyisocyanate composition.

8. The method for preparing a polyisocyanate composition according to claim 7, characterized in that: In S1, the cumulative added mass content of xylylene diisocyanate is 4%-20% based on the total mass of xylylene diisocyanate and aliphatic diisocyanate; and / or, the xylylene diisocyanate in S1 is added dropwise; And / or, the catalyst in S1 is not particularly limited; and / or, S1 is performed under an inert gas atmosphere; And / or, the temperature in S1 is raised to 40-120°C.

9. The method for preparing a polyisocyanate composition according to claim 8, characterized in that: There is no particular limitation on the rate of adding xylylene diisocyanate in S1; And / or, the catalyst in S1 is a catalyst that can catalyze xylylene diisocyanate and aliphatic diisocyanate simultaneously.

10. The method for preparing a polyisocyanate composition according to claim 9, characterized in that: The dropping rate of xylylene diisocyanate in S1 is controlled to be 50-100 minutes; And / or, the catalyst in S1 is one or more of trimethylhydroxyethylammonium, tetrabutylammonium hydroxide, triethylhydroxypropylammonium, tetramethylammonium acetate, tetrabutylammonium acetate, tetramethylammonium propionate, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriphenylphosphine chloride, and 2,4,6-tris(dimethylaminomethyl)phenol.

11. The method for preparing a polyisocyanate composition according to claim 7, characterized in that: When the polymerization conversion rate of the aliphatic diisocyanate in S2 reaches 35-65%, a terminator is added to terminate the reaction; And / or, in S2, unreacted aliphatic diisocyanate and xylylene diisocyanate are removed by distillation.

12. The method for preparing a polyisocyanate composition according to claim 11, characterized in that: When the polymerization conversion rate of the aliphatic diisocyanate reaches 40-50% in S2, a terminator is added to terminate the reaction.

13. A polyurethane resin, prepared by mixing the polyisocyanate composition according to any one of claims 1 to 6 as a curing agent with a polyol component at an isocyanate group / hydroxyl group molar ratio (NCO / OH) of 1 to 1.

1.

14. A polyurethane composite material, prepared by coating the polyurethane resin according to claim 13 on a substrate, wherein the substrate is a surface of metal and / or plastic.

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