Dual-curing type polyisocyanate composition as well as preparation method and application thereof

Abstract

The invention relates to a dual-curing type polyisocyanate composition as well as a preparation method and application thereof. The polyisocyanate composition comprises a product containing an isocyanurate structure, which is formed by reacting aliphatic diisocyanate with 3-isopropyl-dimethyl benzyl isocyanate, and the polyisocyanate composition at least comprises two isocyanurate mononuclear bodies. The polyisocyanate composition prepared by the invention has the characteristics of UV-thermal dual curing property, low product viscosity, good thermal storage stability and the like, is simple in manufacturing process, and is particularly suitable for protection in the field of circuit boards or 3C electronic products.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and specifically relates to a dual-curing polyisocyanate composition and a preparation method and use thereof Background Art

[0002] In recent years, photocurable resins have been developing rapidly with their environmental protection, high efficiency and energy saving characteristics, and their market share is increasing. Polyurethane acrylate (PUA) is a relatively common and widely used UV light-curable resin. It is a material that combines the characteristics of polyurethane and acrylate. It has a high light curing speed, good adhesion, flexibility, wear resistance and temperature resistance, as well as outstanding high elasticity and elongation. This type of resin has been widely used in metal, wood, plastic coating, ink printing, fabric printing, optical fiber coating, etc., showing its broad application prospects and excellent performance. Among them, aliphatic polyurethane acrylates also have excellent weather resistance relative to aromatic ones. Since the molecular structure of traditional polyurethane acrylates contains a large number of -NHCOO- groups, part of the excellent curing performance is due to the formation of hydrogen bonds in the polyurethane matrix. However, these hydrogen bonds are the reason why traditional polyurethane acrylates have a high viscosity. In order to reduce the viscosity of the formulation system, a large amount of reactive diluents need to be added. Especially in the field of UV curing, the introduction of too much diluent will affect the shrinkage rate and thermal storage stability of the product. CN114163972A and CN102498164A disclose double bond compounds containing both isocyanate groups and free radical polymerizable compounds. These compounds are first formed by dimerization or trimerization of aliphatic isocyanates commonly used in industry to form uretdione or isocyanurate counterparts, and then reacted with (methyl) acrylate hydroxy esters. The advantage of this system is to avoid the risk of polymerization in the free monomer removal link, but they often have very high viscosity and need to be diluted with a large amount of solvent before use. In addition, when stored at low temperatures, turbidity or crystallization caused by the precipitation of carbamate is prone to occur. CN107629189A discloses a low-viscosity polyurethane acrylate oligomer, and the prepared product has good weather resistance and compatibility, and the curing speed of the product is significantly improved, but the product prepared by this method does not contain free NCO, and all NCO groups are reacted during the preparation process, resulting in a still large viscosity of the product, and in a strict sense, it no longer has the characteristics of dual curing. CN115466568A discloses a UV / moisture dual-curing protective coating and its preparation method and application. This solution directly uses TDI or MDI as a raw material to react with polypropylene glycol and HEMA. The product contains a large amount of carbamate structure and a large amount of free TDI or MDI, which poses a great challenge to the product's thermal storage stability and environmental hazards.

[0003] In some applications and conditions, pure UV-curable acrylate coatings or polyurethane-modified acrylate copolymer coatings may be inhibited by the contact of the coating surface with oxygen in the air during the curing process, or some areas may not be exposed to ultraviolet light due to the uneven surface, resulting in incomplete curing of the coating surface or even the entire coating, which will seriously affect the performance of the protective coating. Therefore, the development of isocyanate compositions with dual-curing properties has always been an urgent problem to be solved in the industry, especially isocyanate products with both low viscosity and good thermal storage stability. Summary of the invention

[0004] One of the purposes of the present invention is to overcome the defects of the prior art and provide a polyisocyanate composition, which not only ensures that the product has dual curing properties, but also has the characteristics of low product viscosity, good thermal storage stability and good application performance.

[0005] The present invention is achieved through the following technical solutions:

[0006] A polyisocyanate composition, comprising a product containing an isocyanurate structure formed by the reaction of an aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate, and the composition comprises two isocyanurate mononuclear bodies of structure (I) and structure (II):

[0007]

[0008] In the above formulae (I) and (II), R1 is a residual group obtained by removing the isocyanate group from an aliphatic diisocyanate.

[0009] The polyisocyanate composition of the present invention uses aliphatic diisocyanate because the aliphatic isocyanate structure itself has good weather resistance and moderate reactivity. Through the unique isocyanurate polymerization process, the inventor surprisingly found that, on the one hand, the double bond group is directly polymerized into the urethane ring of the traditional isocyanate to form a six-membered ring structure with good mechanical properties and thermal stability, and the introduction of thermally unstable urethane structure can be avoided. On the other hand, due to the moderate increase in the asymmetric structure formed by the aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate, the product has a good operating viscosity, and the amount of solvent or reactive diluent used can be avoided or reduced.

[0010] In addition, it was unexpectedly discovered that by cross-copolymerizing aliphatic diisocyanates and 3-isopropyl-dimethylbenzyl isocyanate, the reaction system contains a certain amount of isocyanurate mononuclear structure with double bond groups. Compared with the prior art, the composition not only has highly adjustable UV-heat dual curing properties, but also avoids the introduction of thermally unstable carbamate or allophanate structures, thereby ensuring good storage stability.

[0011] In one embodiment of the present invention, the polyisocyanate composition comprises an aliphatic diisocyanate oligomer, two isocyanurate mononuclear bodies, a free aliphatic diisocyanate monomer and a free 3-isopropyl-dimethylbenzyl isocyanate; preferably, the ratio of structure (I) to structure (II) of the isocyanurate mononuclear body is (10-50):100, preferably (15-40):100; preferably, the sum of the contents of the free aliphatic diisocyanate monomer and the free 3-isopropyl-dimethylbenzyl isocyanate monomer is less than 0.5%, based on the total mass of the composition.

[0012] In one embodiment of the present invention, the aliphatic diisocyanate is selected from any aliphatic diisocyanate having two terminal isocyanate groups and the isocyanate groups are not directly connected to the benzene ring. 30 The compound is preferably at least one of pentamethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate, and more preferably one or more of hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

[0013] Another object of the present invention is to provide a method for preparing the polyisocyanate composition.

[0014] A method for preparing a polyisocyanate composition, wherein the composition is the above-mentioned polyisocyanate composition, and the preparation method comprises the following steps:

[0015] The aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate react under a catalyst condition, the reaction is terminated to obtain an isocyanate mixture solution, and unreacted aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are removed to obtain a target polyisocyanate composition.

[0016] In one embodiment of the present invention, the reaction temperature is 45-100°C.

[0017] In one embodiment of the present invention, the catalyst is a catalyst that can simultaneously catalyze the reaction of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate to form structure I and structure II, preferably an organic amine compound and / or an organic phosphorus compound, more preferably one or more of trimethylhydroxyethylammonium, triethylhydroxypropylammonium, tetramethylammonium acetate, tetrabutylammonium acetate, tetramethylammonium propionate, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriphenylphosphonium chloride, and 2,4,6-tris(dimethylaminomethyl)phenol; preferably, the catalyst is added in an amount of 20-1500ppm based on the total mass of the aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate.

[0018] Optionally, in order to make the reaction process have good reaction selectivity and high catalytic activity, a co-catalyst can be added. The co-catalyst is not particularly limited, and preferably has good induction activity for the hybrid polymerization process, such as one or more of five-membered or six-membered heterocyclic organic compounds containing nitrogen atoms, phosphorus atoms, oxygen atoms or sulfur atoms, preferably one or more of pyrazole, imidazole, pyrrole, thiophene, furan, pyridine, and pyridazine.

[0019] Optionally, in order to reduce the gel tendency of the system caused by free radical polymerization of 3-isopropyl-dimethylbenzyl isocyanate itself, a free radical inhibitor can be added. The free radical inhibitor is not particularly limited and can be selected from at least one of hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, phenothiazine, and p-benzoquinone, preferably phenothiazine.

[0020] In one embodiment of the present invention, the termination reaction is to add a terminator to terminate the reaction; preferably, the reaction is terminated when the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reaches 20-60%, preferably 25-50%. The terminator is an acid compound, preferably at least one 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. The terminator and its use method are common techniques in the art.

[0021] Another object of the present invention is to provide a use of the polyisocyanate composition.

[0022] A use of a polyisocyanate composition, wherein the composition is the polyisocyanate composition described above, or is a composition prepared by the preparation method described above, and the composition is used for coatings or adhesives, preferably for two-component coatings with dual-curing properties, and more preferably for coatings on circuit boards or plastic substrates.

[0023] Another object of the present invention is to provide a curing agent with dual curing properties.

[0024] A curing agent with dual curing properties, the curing agent adopts the above-mentioned polyisocyanate composition, or a composition prepared by the above-mentioned preparation method, and the curing agent contains the polyisocyanate composition.

[0025] Another object of the present invention is to provide a two-component coating having dual curing properties.

[0026] A two-component coating with dual curing properties, the coating adopts the above-mentioned polyisocyanate composition, or the composition prepared by the above-mentioned preparation method, or the above-mentioned curing agent, and the coating adopts the polyisocyanate composition as the curing agent component.

[0027] The method for preparing two-component coatings from polyisocyanates is well known to those skilled in the art, that is, a two-component curing product mainly using polyisocyanates as curing agents, polyester polyols containing active hydrogen or hydroxy acrylic resins as main agents, and adding a number of functional additives and active monomers according to actual needs. The present invention can preferably adopt the following method to prepare UV-heat-curing two-component coatings from polyisocyanate compositions: at 15-35°C and relative humidity below 40%, add selected weights of hydroxy acrylic resin, n-butyl acetate, trimethylolpropane triacrylate, photoinitiator and other coating additives to a batching container, stir mechanically to mix evenly, add the above-prepared polyisocyanate composition according to an NCO / OH ratio of 1.01-1.08, stir mechanically for 3-8 minutes to mix evenly, and remove bubbles by vacuum at room temperature to obtain a polyurethane coating that can be UV-heat-cured dually.

[0028] The auxiliary agent can be one of auxiliary agents such as a defoamer, a wetting agent, a dispersant, a leveling agent, a silane coupling agent, etc., or a mixture of any of them.

[0029] Unless otherwise specified, % in the present invention refers to wt%.

[0030] Unless otherwise specified, the inert gas is preferably nitrogen.

[0031] The technical solution provided by the present invention has the following beneficial effects:

[0032] The product prepared by the technical solution can greatly improve the quick-drying performance and application performance of the product while ensuring that the final composition has a relatively low operating viscosity, especially in terms of high temperature and high humidity hydrolysis resistance and moisture and heat aging resistance. Therefore, it is particularly suitable for use in fields with dual curing requirements, such as circuit boards and 3C electronic plastic substrates. DETAILED DESCRIPTION

[0033] 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.

[0034] Some of the raw materials and their sources used in the following examples and comparative examples of the present invention are as follows:

[0035] Isophorone diisocyanate (IPDI) was purchased from Wanhua Chemical Group Co., Ltd.

[0036] Hexamethylene diisocyanate (HDI) was purchased from Wanhua Chemical Group Co., Ltd.;

[0037] Hexamethylene diisocyanate trimer (HT-100), an aliphatic isocyanurate, was purchased from Wanhua Chemical Group Co., Ltd.;

[0038] Phenothiazine, polymerization inhibitor, was purchased from Aladdin Reagent (Shanghai) Co., Ltd.;

[0039] UV-1173, photoinitiator, purchased from Jiangxi Lotte Chemical Co., Ltd.;

[0040] 3-isopropyl-dimethylbenzyl isocyanate (TMI), a specialty isocyanate, was purchased from Merck Chemical AG;

[0041] AC1260, hydroxylated acrylic resin, a common resin for polyurethane two-component varnish, purchased from Foshan Gaoming Tongde Chemical Co., Ltd.;

[0042] BYK306, a commonly used leveling agent for polyurethane coatings, was purchased from BYK Chemical Co., Ltd., Germany;

[0043] Imidazole, a co-catalyst, was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0044] Unless otherwise specified, the contents in the present invention are all by mass.

[0045] In the following embodiments and comparative examples of the present invention, the relevant testing methods are as follows:

[0046] (1) NCO content test is carried out in accordance with GB / T 12009.4;

[0047] (2) Viscosity test: The dynamic viscosity at 25°C was measured using a Brookfield DT-2 viscometer.

[0048] (3) The method for analyzing the structure of isocyanurate mononuclear body is as follows:

[0049] The AVANCE600 manufactured by Bruker FT-NMR was used, with deuterated chloroform (CDCl3) as solvent, and the sample (prepared isocyanurate product) was 5% by mass, 600 MHz, and scanned for 48 hours. 13 C nuclear magnetic resonance spectrum was used for qualitative analysis. The carbon spectrum characteristic shifts of the six-membered ring structure of isocyanurate shown in structure I prepared based on hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were around δ148.3ppm, δ150.7ppm, and δ150.7ppm, respectively. Structure II is a standard six-membered ring structure of isocyanurate. The carbon spectrum characteristic shifts of structure II prepared based on hexamethylene diisocyanate were all around δ148.5ppm.

[0050] (4) The ratio of isocyanurate mononuclear structure (I) / (II) is tested as follows: the terminal isocyanate groups in the polyisocyanate composition are derivatized with methanol and analyzed by liquid chromatography-mass spectrometry (LC / MS). The configuration and testing method are as follows:

[0051] (a) Sample preparation method: A certain amount of polyisocyanate composition is weighed and diluted with a stoichiometric excess of methanol, and the mixture is allowed to stand for three days to allow the existing isocyanate groups to completely react with methanol, thereby preparing a methanol derivative solution.

[0052] (b) Determination method:

[0053] The methanol derivative solution obtained above was measured using the following apparatus.

[0054] Agilent LC (liquid chromatograph), Agilent 1100 series

[0055] Column: Phenomenex, Kinetex 2.6μXB-C18 100A, (inner diameter 2.1 mm, length 50 mm)

[0056] Column temperature: 40°C

[0057] Detection: 205nm

[0058] Flow rate: 0.35mL / mins

[0059] Mobile phase: gradient of A and B solutions, A = water (0.05% formic acid), B = methanol

[0060] Injection volume: 2μL

[0061] Thermo MS (mass spectrometer)

[0062] Device: Thermo Electron, LCQ

[0063] Ionization: APCI

[0064] Mode: Positive

[0065] Scan range: m / z 150 ~ 2000.

[0066] The ratio of the methanol adduct of structure (I) to the methanol adduct of structure (II) was taken as the ratio of isocyanurate mononuclear structure (I) / (II).

[0067] (5) The sum of the free aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was tested by establishing an external standard curve using high performance liquid chromatography (HPLC). The key parameters can be referred to as follows:

[0068] Chromatographic column: Waters XSelect HSS T3 5um 4.6*250mm;

[0069] Automatic sample injector: SIL-20A

[0070] Column temperature: 40°C

[0071] Injection volume: 10 μL

[0072] Detection wavelength: 281nm

[0073] Derivatization reagent: 4% 1-methoxyphenylpiperazine-acetonitrile solution.

[0074] The concentrations of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were calculated based on their respective peak areas and external standard curves, and the sum of the two concentrations was taken as the sum of the monomer contents of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate in the polyisocyanate composition.

[0075] (6) Thermal storage stability of polyisocyanate: The isocyanate composition sample was placed in a 120 ml brown glass bottle with a ground mouth, and the air atmosphere was replaced with nitrogen. After replacement, the bottle was sealed and stored at 80°C. The viscosity growth rate was tested after 30 days.

[0076] Evaluation criteria: If the viscosity growth rate is less than 10%, the thermal storage stability is considered excellent;

[0077] If the viscosity growth rate is 10% < 20%, the thermal storage stability is evaluated as good;

[0078] If the viscosity increase rate is >20%, the thermal storage stability is evaluated as poor.

[0079] Polyisocyanate composition preparation.

[0080] Example 1

[0081] Under an inert gas atmosphere, 500 g of hexamethylene diisocyanate and 200 g of 3-isopropyl-dimethylbenzyl isocyanate were weighed into a reaction container and heated to 80° C., then 0.07 g of phenothiazine was added and stirred to disperse evenly, and then 0.32 g of tetrabutylammonium hydroxide catalyst and 0.10 g of imidazole were added to carry out trimerization until the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reached 20%, and 0.1 g of dibutyl phosphate was added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were further removed by thin film distillation at 150° C. and vacuum degree <500 Pa. After analysis, the NCO content was 18.2%, the viscosity was 4810 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) was 15.1%, the sum of the free hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was 0.32%, and the thermal storage stability of the polyisocyanate composition was evaluated as excellent.

[0082] Example 2

[0083] Under an inert gas atmosphere, 500 g of hexamethylene diisocyanate and 400 g of 3-isopropyl-dimethylbenzyl isocyanate were weighed into a reaction container and heated to 60° C., then 0.09 g of phenothiazine was added and stirred to disperse evenly, and then 0.32 g of tetrabutylammonium hydroxide catalyst and 0.35 g of imidazole were added to carry out trimerization until the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reached 50%, and 0.2 g of dibutyl phosphate was added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were further removed by thin film distillation at 150° C. and vacuum degree <500 Pa. After analysis, the NCO content was 15.1%, the viscosity was 6891 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) was 44.5%, the sum of the free hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was 0.35%, and the thermal storage stability of the polyisocyanate composition was evaluated as excellent.

[0084] Example 3

[0085] Under an inert gas atmosphere, 500 g of isophorone diisocyanate and 200 g of 3-isopropyl-dimethylbenzyl isocyanate were weighed into a reaction container and heated to 80 ° C, and then 0.07 g of phenothiazine was added and stirred to disperse evenly, and then 0.45 g of tetrabutylammonium hydroxide catalyst and 0.25 g of imidazole were added to carry out trimerization until the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reached 35%, and 0.2 g of dibutyl phosphate was added to terminate the reaction to obtain an isocyanate mixture solution, and the unreacted isophorone diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were further removed by thin film distillation at 150 ° C and vacuum <500 Pa. After analysis, the NCO content was 15.7%, the viscosity was 11326 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) was 25.6%, the sum of the free isophorone diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was 0.43%, and the thermal storage stability of the polyisocyanate composition was evaluated as excellent.

[0086] Example 4

[0087] Under an inert gas atmosphere, 500 g of hexamethylene diisocyanate and 100 g of 3-isopropyl-dimethylbenzyl isocyanate were weighed into a reaction container and heated to 80° C., then 0.06 g of phenothiazine was added and stirred to disperse evenly, and then 0.40 g of trimethylhydroxyethylammonium catalyst and 0.10 g of imidazole were added to carry out trimerization until the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reached 35%, and 0.2 g of dioctyl phosphate was added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were further removed by thin film distillation at 150° C. and vacuum degree <500 Pa. After analysis, the NCO content was 18.9%, the viscosity was 3798 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) was 11.2%, the sum of the free hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was 0.12%, and the thermal storage stability of the polyisocyanate composition was evaluated as excellent.

[0088] Comparative Example 1

[0089] Comparative Example 1 is compared with the above-mentioned Example 4, and the only difference is that the product with dual curing properties is prepared without using diisocyanate monomer, and therefore only contains structure II but not structure I.

[0090] The preparation method of the polyisocyanate composition of this comparative example comprises the following steps: under an inert gas atmosphere, 500 g of hexamethylene diisocyanate trimer (HT-100) and 100 g of 3-isopropyl-dimethylbenzyl isocyanate are weighed into a reaction container, heated to 80°C and directly blended and modified, and then 0.06 g of phenothiazine is added and stirred and dispersed uniformly, so that it satisfies the dual curing characteristics. After analysis, the NCO content is 21.8%, the viscosity is 489 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) is 0, and the thermal storage stability of the polyisocyanate composition is evaluated as poor.

[0091] Comparative Example 2

[0092] Compared with Example 2, the only difference is that the added amount of 3-isopropyl-dimethylbenzyl isocyanate is increased.

[0093] The preparation method of the polyisocyanate composition of the comparative example comprises the following steps: under an inert gas atmosphere, 500 g of hexamethylene diisocyanate and 700 g of 3-isopropyl-dimethylbenzyl isocyanate are weighed into a reaction container and the temperature is raised to 60° C., then 0.09 g of phenothiazine is added and stirred to disperse uniformly, and then 0.32 g of tetrabutylammonium hydroxide catalyst and 0.35 g of imidazole are added to carry out trimerization reaction until the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reaches 50%, and 0.2 g of dibutyl phosphate is added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are removed by thin film distillation at 150° C. and vacuum degree <500 Pa. After analysis, the NCO content was 12.2%, the viscosity was 8691 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) was 65.7%, the sum of the free hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was 0.22%, and the thermal storage stability of the polyisocyanate composition was evaluated as good.

[0094] Comparative Example 3

[0095] Compared with Example 4, the only difference is that the added amount of 3-isopropyl-dimethylbenzyl isocyanate is reduced.

[0096] Under an inert gas atmosphere, 500 g of hexamethylene diisocyanate and 30 g of 3-isopropyl-dimethylbenzyl isocyanate were weighed into a reaction container and heated to 80° C., then 0.06 g of phenothiazine was added and stirred to disperse evenly, and then 0.40 g of trimethylhydroxyethylammonium catalyst and 0.10 g of imidazole were added to carry out trimerization until the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reached 35%, and 0.2 g of dioctyl phosphate was added to terminate the reaction to obtain an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate were further removed by thin film distillation at 150° C. and vacuum degree <500 Pa. After analysis, the NCO content was 19.8%, the viscosity was 3489 cP / 25°C, the ratio of isocyanurate mononuclear structure (I) / structure (II) was 2.8%, the sum of the free hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate monomer contents was 0.11%, and the thermal storage stability of the polyisocyanate composition was evaluated as excellent.

[0097] Application examples of polyisocyanate compositions.

[0098] The polyisocyanate composition is used as a raw material to prepare a UV-heat-curing two-component coating according to the following process: at 25° C. and a relative humidity of less than 40%, 50 parts of hydroxy acrylic resin AC-1260, 45 parts of butyl acetate, 5 parts of trimethylolpropane triacrylate, 150 ppm of photoinitiator UV-1173 and 50 ppm of BYK306 are added to a batching container respectively, and after mechanical stirring and mixing, the prepared polyisocyanate composition is added according to a metering ratio of NCO / OH of 1.05, and mechanical stirring is performed for 5 minutes to make it uniformly mixed, and vacuum is evacuated at room temperature to remove bubbles, so as to obtain a polyurethane coating that can be UV-heat-cured.

[0099] The coating composition obtained above was sprayed evenly on the circuit board or PET film and the tetrafluoroethylene mold, and then placed in a UV curing machine for curing for 10 seconds. The main wavelength of the UV curing machine used in the experiment was 365nm, and the power density was 60W / cm 2 After UV curing, the samples were placed at 50°C for 3 hours to achieve complete curing, and then the test samples were obtained for performance testing.

[0100] (1) The surface drying time is tested in accordance with GB / T 1728-2020.

[0101] (2) High temperature and high humidity hydrolysis resistance test: The test sample was cut into sheets of 15 mm*200 mm, placed in a pressure cooker, and treated at a high temperature and high pressure environment of 120°C and 0.1 MPa for 25 hours. After being taken out, it was aged at room temperature for 1 day, and then a 180° peel test was performed using a tensile strength testing machine at a test speed of 50 mm / min.

[0102] Evaluation criteria: Peel strength ≥ 10N / 15mm is excellent;

[0103] 6N / 15mm≤Peel strength≤10N / 15mm is good;

[0104] 1N / 15mm≤Peel strength≤6N / 15mm is poor;

[0105] (3) Weathering test: The test sample was cut into sheets of 50 mm*150 mm, and an accelerated aging test was performed on the composite layer using a xenon lamp weathering tester. The appearance after light aging was observed according to the ASTM G155 standard.

[0106] Evaluation criteria: No change is excellent;

[0107] Slight discoloration or cracks are good;

[0108] If there is obvious discoloration or cracks, it is considered poor;

[0109] (4) Moisture and heat aging resistance test: The test specimens were cut into 15 mm*200 mm sheets and placed in a high temperature and high humidity test chamber. The experimental conditions were: humidity 85%, temperature 85°C, and time 1000 h. Moisture and heat aging resistance test was performed to observe whether the coating layer was powdered or had bubbles. The cross-hatch method was used to test adhesion. If more than 95% of the samples did not fall off, the samples were qualified. The rest were unqualified.

[0110] The performance test results of the coating samples prepared from the polyisocyanate compositions obtained in the examples and comparative examples are shown in Table 1.

[0111] Table 1 Performance test results of test samples prepared by polyisocyanate in the embodiment and comparative example

[0112]

[0113] From the macroscopic indicators of the polyisocyanate compositions prepared in Examples 1-4 and Comparative Examples 1-3 and the performance test results of the products in Table 1, it can be seen that the polyisocyanate compositions prepared in Examples 1-4 have relatively low viscosity and excellent thermal storage stability. At the same time, the prepared test samples have excellent performance in terms of performance indicators such as hydrolysis resistance and resistance to wet and hot aging under high temperature and high humidity, and have the advantage of short surface drying time; while the polyisocyanates prepared in Comparative Examples 1-4 cannot simultaneously meet the conditions of low viscosity and good comprehensive product performance, and therefore are difficult to meet actual needs.

[0114] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, 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 therefrom are still within the scope of protection of the invention.

Claims

1. A polyisocyanate composition, characterized in that: The polyisocyanate composition comprises a product containing an isocyanurate structure formed by the reaction of an aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate, and the composition comprises two isocyanurate mononuclear bodies of structure (I) and structure (II): In the above formulae (I) and (II), R1 is a residual group obtained by removing the isocyanate group from an aliphatic diisocyanate.

2. The polyisocyanate composition according to claim 1, characterized in that The polyisocyanate composition comprises an aliphatic diisocyanate oligomer, two isocyanurate mononuclear bodies, a free aliphatic diisocyanate monomer and a free 3-isopropyl-dimethylbenzyl isocyanate; Preferably, the ratio of structure (I) to structure (II) of the isocyanurate mononuclear body is (10-50):100, preferably (15-40):100; Preferably, the sum of the free aliphatic diisocyanate monomer content and the free 3-isopropyl-dimethylbenzyl isocyanate monomer content is less than 0.5%, based on the total mass of the composition.

3. The polyisocyanate composition according to claim 1 or 2, characterized in that: The aliphatic diisocyanate is selected from any carbon number between C4 and C5 containing two terminal isocyanate groups and the isocyanate groups are not directly connected to the benzene ring. 30 The compound is preferably at least one of pentamethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate, and more preferably one or more of hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

4. A method for preparing a polyisocyanate composition, wherein the composition is the polyisocyanate composition according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: The aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate react under a catalyst condition, the reaction is terminated to obtain an isocyanate mixture solution, and unreacted aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are removed to obtain a target polyisocyanate composition.

5. The preparation method according to claim 4, characterized in that: The reaction temperature is 45-100°C; And / or, the catalyst is a catalyst that can simultaneously catalyze the reaction of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate to form structure I and structure II, preferably an organic amine compound and / or an organic phosphorus compound, more preferably one or more of trimethylhydroxyethylammonium, triethylhydroxypropylammonium, tetramethylammonium acetate, tetrabutylammonium acetate, tetramethylammonium propionate, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriphenylphosphonium chloride, and 2,4,6-tris(dimethylaminomethyl)phenol; Preferably, the amount of catalyst added is 20-1500 ppm based on the total mass of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate; And / or, the termination reaction is to add a terminator to terminate the reaction; Preferably, the reaction is terminated when the conversion rate of 3-isopropyl-dimethylbenzyl isocyanate reaches 20-60%, preferably 25-50%.

6. Use of a polyisocyanate composition, wherein the composition is the polyisocyanate composition according to any one of claims 1 to 3, or is a composition prepared by the preparation method according to claim 4 or 5, and the composition is used for coatings or adhesives, preferably for two-component coatings with dual-cure properties, and more preferably for coatings on circuit boards or plastic substrates.

7. A curing agent with dual curing properties, wherein the curing agent is a polyisocyanate composition according to any one of claims 1 to 3, or a composition prepared by the preparation method according to claim 4 or 5, characterized in that: The curing agent contains a polyisocyanate composition.

8. A two-component coating with dual curing properties, wherein the coating adopts the polyisocyanate composition according to any one of claims 1 to 3, or the composition prepared by the preparation method according to claim 4 or 5, or the curing agent prepared by the preparation method according to claim 7, characterized in that: The coating adopts a polyisocyanate composition as a curing agent component.

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