CN119591835A - Dual-curing type polyisocyanate composition and preparation method and application thereof - Google Patents

Abstract

The invention relates to a dual-curing type polyisocyanate composition, a preparation method and application thereof. The polyisocyanate composition comprises an isocyanurate structure-containing product formed from the reaction of an aliphatic diisocyanate with 3-isopropyl-dimethylbenzyl isocyanate, and it comprises at least two isocyanurate mononuclei. The polyisocyanate composition prepared by the invention has the characteristics of UV-heat dual curing property, low product viscosity, good thermal storage stability and the like, and the manufacturing process is simple, so that the polyisocyanate composition is particularly suitable for protecting the field of circuit boards or 3C electronic products.

Description

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

Technical Field

The invention belongs to the field of high polymer materials, and in particular relates to a dual-curing type polyisocyanate composition, a preparation method and application thereof

Background

In recent years, the development of photo-curing resins by virtue of the characteristics of environmental protection, high efficiency and energy conservation is vigorous, and the market share is increasing. Polyurethane acrylate (PUA) is a relatively common and widely used UV light-cured resin, and combines polyurethane and acrylate characteristics, and has high light-curing speed, good adhesion, flexibility, wear resistance and temperature resistance, and outstanding high elasticity and elongation. The resin has been widely used in metal, wood, plastic coating, ink printing, textile printing, optical fiber coating, etc., and shows wide application prospect and excellent performance. Among them, aliphatic urethane acrylates have excellent weather resistance as compared with aromatic urethane acrylates. Since the molecular structure of conventional urethane acrylates contains a large number of-NHCOO-groups, some of the excellent curing properties are due to the formation of hydrogen bonds within the urethane matrix. These hydrogen bonds are responsible for the higher viscosity of conventional urethane acrylates. In order to reduce the viscosity of the formulation, a large amount of reactive diluent is required to be added, and especially in the field of UV curing, the introduction of excessive diluent has an influence on the shrinkage rate and the thermal storage stability of the product. CN114163972a and CN102498164A disclose compounds containing both isocyanate groups and free-radically polymerizable double bonds, which compounds are derived from uretdione or isocyanurate counterparts formed by dimerization or trimerization of aliphatic isocyanates commonly used in industry, which counterparts are reacted with (meth) acrylate hydroxyesters, which systems have the advantage that the risk of polymerization occurs in the avoidance of free monomer removal links, but they tend to have very high viscosities, require dilution with large amounts of solvents for use, and are prone to haze or crystallization due to urethane precipitation upon storage at low temperatures. CN107629189a discloses a low-viscosity polyurethane acrylate oligomer, the prepared product has good weather resistance and compatibility, and the curing speed of the product is obviously improved, but the product prepared by the method does not contain free NCO, all NCO groups react in the preparation process, so that the product viscosity is still larger, and the product has no dual curing characteristic in strict sense. CN115466568a discloses an ultraviolet light/moisture dual curing protective coating, a preparation method and application thereof, the scheme directly adopts TDI or MDI as raw material to react with polypropylene glycol and HEMA, and the product contains a large amount of carbamate structures and contains a large amount of free TDI or MDI, which brings great challenges to thermal storage stability and environmental hazard of the product.

Under some application occasions and conditions, the pure UV-cured acrylate coating or polyurethane modified acrylate copolymer coating can cause polymerization inhibition due to the fact that the surface of the coating contacts oxygen in the air or the like in the curing process, or can not irradiate partial areas to ultraviolet light due to uneven surface, so that the surface of the coating is not completely cured even in whole, and the performance of the protective coating can be seriously affected. The development of isocyanate compositions having dual cure properties has therefore been a problem to be solved in the industry, in particular isocyanate products which combine low viscosity with good heat storage stability.

Disclosure of Invention

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

The invention is realized by the following technical scheme:

A polyisocyanate composition comprising an isocyanurate structure-containing product formed by reacting an aliphatic diisocyanate with 3-isopropyl-dimethylbenzyl isocyanate, said composition comprising two isocyanurate mononuclei of structure (I) and structure (II):

Wherein, in the above formulas (I) and (II), R ₁ is the residual group of the aliphatic diisocyanate from which the isocyanate group is removed.

The aliphatic diisocyanate is selected as the polyisocyanate composition, and the inventor surprisingly discovers that on one hand, the traditional isocyanate urea acid ester ring is directly polymerized to introduce double bond groups, so that a six-membered ring structure is formed, the mechanical property and the thermal stability are good, and the introduction of a thermally unstable carbamate structure can be avoided through the unique isocyanurate polymerization process. On the other hand, the asymmetric structure formed by the aliphatic diisocyanate and the 3-isopropyl-dimethylbenzyl isocyanate is moderately increased, so that the product has good operation viscosity, and the use amount of a solvent or a reactive diluent can be avoided or reduced.

In addition, it has also been unexpectedly found that by cross-copolymerizing an aliphatic diisocyanate with 3-isopropyl-dimethylbenzyl isocyanate, the reaction system contains a certain amount of isocyanurate mononucleosome structure with double bond groups, and the composition has highly adjustable UV-thermal dual curing characteristics and avoids the introduction of thermally unstable urethane or allophanate structure, thereby ensuring good storage stability.

In one embodiment of the present invention, the polyisocyanate composition comprises an aliphatic diisocyanate oligomer, two isocyanurate mononuclei, an aliphatic diisocyanate monomer in free form and 3-isopropyl-dimethylbenzyl isocyanate in free form, preferably the ratio of structure (I) and structure (II) of the isocyanurate mononuclei is (10-50): 100, preferably (15-40): 100, preferably the sum of the aliphatic diisocyanate monomer in free form and the 3-isopropyl-dimethylbenzyl isocyanate monomer in free form is less than 0.5% by weight based on the total mass of the composition.

In one embodiment of the present invention, the aliphatic diisocyanate is selected from compounds having two terminal isocyanate groups and any carbon number between which the isocyanate groups are not directly attached to the benzene ring is C ₄-C₃₀, preferably at least one of pentamethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, more preferably one or more of hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate.

It is another object of the present invention to provide a process for the preparation of the polyisocyanate composition.

A method of preparing a polyisocyanate composition, said composition being a polyisocyanate composition as described above, said method comprising the steps of:

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

In one embodiment of the invention, the temperature of the reaction is 45-100 ℃.

In one embodiment of the present invention, the catalyst is a catalyst capable of catalyzing the reaction of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate to form structure I and structure II simultaneously, preferably an organic amine compound and/or an organic phosphorus compound, more preferably one or more of trimethyl hydroxyethyl ammonium, triethyl hydroxypropyl ammonium, tetramethyl ammonium acetate, tetrabutyl ammonium acetate, tetramethyl ammonium propionate, tetramethyl ammonium hydroxide, benzyl trimethyl ammonium hydroxide, benzyl triphenyl phosphorus chloride, 2,4, 6-tris (dimethylaminomethyl) phenol, and preferably the catalyst is added in an amount of 20 to 1500ppm based on the total mass of aliphatic diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate.

Optionally, in order to provide a good reaction selectivity and a high catalytic activity in the reaction process, a cocatalyst may be optionally added, which is not particularly limited, and preferably has a good induction activity for the hybrid polymerization process, such as one or more of five-or six-membered heterocyclic organic matters containing nitrogen atom, phosphorus atom, oxygen atom or sulfur atom, preferably one or more of pyrazole, imidazole, pyrrole, thiophene, furan, pyridine, pyridazine.

Optionally, in order to reduce the tendency of the system to gel due to the free radical polymerization of 3-isopropyl-dimethylbenzyl isocyanate itself, a free radical polymerization inhibitor may be optionally added, and the free radical polymerization inhibitor is not particularly limited, and at least one of hydroquinone, p-hydroxyanisole, 2, 6-di-t-butyl p-cresol, phenothiazine, p-benzoquinone is selected, and phenothiazine is preferable.

In one embodiment of the invention, the termination reaction is terminated by adding a terminator, preferably when the reaction reaches a conversion of 20-60%, preferably 25-50%, of 3-isopropyl-dimethylbenzyl isocyanate. 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 terminators and methods of use are conventional in the art.

It is a further object of the present invention to provide the use of a polyisocyanate composition.

Use of a polyisocyanate composition as described above, or a composition prepared by the above preparation method, for a coating or adhesive, preferably for a two-component coating having dual cure properties, more preferably for a film on a circuit board or plastic substrate.

It is still another object of the present invention to provide a curing agent having dual curing characteristics.

A curing agent having dual curing characteristics, which is a composition prepared by using the above polyisocyanate composition or the above preparation method, comprises a polyisocyanate composition.

It is still another object of the present invention to provide a two-component coating having dual cure characteristics.

A two-component coating with dual curing characteristics adopts the polyisocyanate composition, or the composition prepared by the preparation method, or the curing agent, and the coating adopts the polyisocyanate composition as the curing agent component.

The method for preparing the two-component coating from the polyisocyanate is well known to the person skilled in the art, namely, mainly comprises the steps of taking the polyisocyanate as a curing agent, taking polyester polyol or hydroxy acrylic resin containing active hydrogen as a main agent, and selecting a two-liquid curing type product added with a plurality of functional auxiliary agents and active monomers according to actual requirements. The UV-thermosetting two-component coating is prepared from the polyisocyanate composition by the method that the selected weight of hydroxy acrylic resin, n-butyl acetate, trimethylolpropane triacrylate, photoinitiator and other coating auxiliary agents are respectively added into a batching container under the condition that the relative humidity is lower than 40 percent at 15-35 ℃, the polyisocyanate composition is prepared by metering and adding the mixture into the batching container according to the NCO/OH ratio of 1.01-1.08 after the mixture is mechanically stirred and mixed uniformly, the mixture is mechanically stirred for 3-8mins to be uniformly mixed, and the mixture is vacuumized at room temperature to remove bubbles, so that the UV-thermal dual-curable polyurethane coating is obtained.

The auxiliary agent can be one or the mixture of a plurality of auxiliary agents such as an antifoaming agent, a wetting agent, a dispersing agent, a leveling agent, a silane coupling agent and the like.

Unless otherwise indicated, in the present invention the% are all wt%.

The inert gas is preferably nitrogen unless otherwise specified.

The technical scheme provided by the invention has the following beneficial effects:

The product prepared by adopting the technical scheme ensures that the final composition has relatively low operation viscosity, and simultaneously can greatly improve the quick-drying performance and application performance of the product, and particularly, the product is obviously improved in the aspects of high-temperature high-humidity anti-hydrolysis performance and humidity-heat aging resistance, so that the product is particularly suitable for the application fields with double curing requirements, such as circuit boards, 3C electronic plastic substrates and the like.

Detailed Description

For a better understanding of the technical solution of the present invention, the following examples are further described below, but the present invention is not limited to the following examples.

The following examples and comparative examples of the present invention were prepared from the following raw materials in part by sources:

Isophorone diisocyanate (IPDI), available from vancomic chemical group inc;

hexamethylene Diisocyanate (HDI), available from vancomic chemical group limited;

Hexamethylene diisocyanate trimer (HT-100), an aliphatic isocyanurate, available from Wanhua chemical group Co., ltd;

Phenothiazine, inhibitor, available from Ara Ding Shiji (Shanghai) Inc.;

UV-1173, photoinitiator, available from Jiangxi Lot chemical Co., ltd;

3-isopropyl-dimethylbenzyl isocyanate (TMI), a specialty isocyanate available from Merck chemical Co., ltd;

AC1260, hydroxy acrylic resin, a polyurethane two-component varnish commonly used resin, purchased from Gaoming Tongde chemical Co., ltd;

BYK306, a common leveling agent for polyurethane coatings, available from Pick chemical Co., ltd;

imidazole, co-catalyst, available from Ara Ding Shiji (Shanghai) Inc.

Unless otherwise specified, the contents in the present invention are mass contents.

In the following examples and comparative examples of the present invention, the relevant test methods are as follows:

(1) NCO content tests were carried out according to standard GB/T12009.4;

(2) Viscosity test dynamic viscosity at 25 ℃ was measured according to the laminometer (Brookfield DT-2);

(3) The isocyanurate mononuclear body structure analysis method comprises the following steps:

The characteristic shifts of carbon spectrum of the isocyanurate six-membered ring structure shown in the structure I prepared by using Bruker FT-NMR as a solvent and using deuterated chloroform CDCl ₃ and using a ¹³ C nuclear magnetic resonance spectrum of a sample (prepared isocyanurate product) with a mass concentration of 5%, 600MHz and scanning for 48 hours are respectively delta 148.3ppm, delta 150.7ppm and delta 150.7ppm nearby, and the characteristic shifts of carbon spectrum corresponding to the structure II prepared by using hexamethylene diisocyanate as a raw material are all nearby delta 148.5 ppm.

(4) The isocyanurate mononucleosome structure (I)/(II) ratio was measured by derivatizing terminal isocyanate groups in a polyisocyanate composition with methanol and analyzing the resultant mixture by liquid chromatography-mass spectrometry (LC/MS), and the configuration and measurement method were as follows:

(a) The sample preparation method comprises weighing a given amount of polyisocyanate composition, diluting with a stoichiometric excess of methanol, and standing for three days to allow isocyanate groups to react with methanol completely, thereby preparing methanol derivative solution.

(B) The measuring method comprises the following steps:

the methanol derivative solution obtained above was measured using the following apparatus.

Agilent1100series LC (liquid chromatograph)

Phenomenex, kinetex 2.6. Mu. XB-C18 100A, (inner diameter 2.1mm, length 50 mm)

Column temperature of 40 DEG C

Detection at 205nm

Flow rate 0.35mL/min

Gradient of A, B liquid (gradient), a=water (0.05% formic acid), b=methanol

Injection amount of 2. Mu.L

Thermo MS (Mass spectrometer)

Device Thermo Electron, LCQ

Ionization APCI

Mode Positive ion (Positive)

The scanning range is m/z 150-2000.

The ratio of the methanol adduct of structure (I) to the methanol adduct of structure (II) was taken as the ratio of isocyanurate mononucleosome structure (I)/(II).

(5) The sum of the monomer contents of the free aliphatic diisocyanate and the 3-isopropyl-dimethylbenzyl isocyanate is tested, and an external standard curve is established by adopting High Performance Liquid Chromatography (HPLC), and key parameters can be referred to as follows:

Waters XSelect HSS T3 um 4.6 x 250mm;

Automatic sampler SIL-20A

Column temperature of 40 DEG C

Sample injection amount 10. Mu.L

Detection wavelength of 281nm

Derivatization reagent 4% 1-methoxyphenylpiperazine-acetonitrile solution.

The respective concentrations are calculated according to the respective peak areas of the aliphatic diisocyanate and the 3-isopropyl-dimethylbenzyl isocyanate and the external standard curve, and the sum of the two concentrations is used as the sum of the monomer contents of the aliphatic diisocyanate and the 3-isopropyl-dimethylbenzyl isocyanate in the polyisocyanate composition.

(6) Polyisocyanate thermal storage stability A sample of the isocyanate composition was placed in a 120ml ground brown glass bottle and replaced with nitrogen in the atmosphere, after which the bottle was stored in a closed condition at 80℃and tested for viscosity build up after 30 days.

An evaluation criterion that the thermal storage stability is evaluated to be excellent if the viscosity increase rate is less than 10%;

10% < viscosity increase <20%, the thermal storage stability was evaluated as good;

the thermal storage stability was evaluated as poor if the viscosity increase rate was > 20%.

Polyisocyanate composition preparation.

Example 1

Under inert gas atmosphere, 500g of hexamethylene diisocyanate and 200g of 3-isopropyl-dimethylbenzyl isocyanate are respectively weighed into a reaction vessel and heated to 80 ℃, then 0.07g of phenothiazine is added, stirred and dispersed uniformly, then 0.32g of tetrabutylammonium hydroxide catalyst and 0.10g of imidazole are added for trimerization reaction until the conversion rate of the 3-isopropyl-dimethylbenzyl isocyanate reaches 20%, 0.1g of dibutyl phosphate is added for terminating the reaction, thus obtaining an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are further removed through thin film distillation under the conditions of 150 ℃ and vacuum degree of <500 Pa. According to analysis, the NCO content was 18.2%, the viscosity was 4810cP/25℃and the ratio of isocyanurate mononuclear structure (I)/structure (II) was 15.1%, the sum of the monomer contents of hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate in the free state was 0.32%, and the thermal storage stability of the polyisocyanate composition was evaluated to be excellent.

Example 2

500G of hexamethylene diisocyanate and 400g of 3-isopropyl-dimethylbenzyl isocyanate are respectively weighed into a reaction vessel under an inert gas atmosphere, the temperature is raised to 60 ℃, then 0.09g of phenothiazine is added, stirring and dispersing are carried out uniformly, then 0.32g of tetrabutylammonium hydroxide catalyst and 0.35g of imidazole are added for trimerization reaction until the conversion rate of the 3-isopropyl-dimethylbenzyl isocyanate reaches 50%, 0.2g of dibutyl phosphate is added for terminating the reaction, an isocyanate mixture solution is obtained, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are further removed through thin film distillation under the conditions of 150 ℃ and vacuum degree of less than 500 Pa. According to analysis, the NCO content was 15.1%, the viscosity was 6891cP/25℃and the ratio of isocyanurate mononuclear structure (I)/structure (II) was 44.5%, the sum of the monomer contents of hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate in the free state was 0.35%, and the thermal storage stability of the polyisocyanate composition was evaluated to be excellent.

Example 3

Under inert gas atmosphere, 500g of isophorone diisocyanate and 200g of 3-isopropyl-dimethylbenzyl isocyanate are respectively weighed into a reaction vessel and heated to 80 ℃, then 0.07g of phenothiazine is added, stirred and dispersed uniformly, then 0.45g of tetrabutylammonium hydroxide catalyst and 0.25g of imidazole are added for trimerization reaction until the conversion rate of the 3-isopropyl-dimethylbenzyl isocyanate reaches 35%, 0.2g of dibutyl phosphate is added for terminating the reaction, thus obtaining an isocyanate mixture solution, and unreacted isophorone diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are further removed through thin film distillation under the conditions of 150 ℃ and vacuum degree of <500 Pa. According to analysis, the NCO content was 15.7%, the viscosity was 11326cP/25℃and the ratio of isocyanurate mononuclear structure (I)/structure (II) was 25.6%, the sum of the monomer contents of isophorone diisocyanate in the free state and 3-isopropyl-dimethylbenzyl isocyanate was 0.43%, and the thermal storage stability of the polyisocyanate composition was evaluated to be excellent.

Example 4

Under inert gas atmosphere, 500g of hexamethylene diisocyanate and 100g of 3-isopropyl-dimethylbenzyl isocyanate are respectively weighed into a reaction vessel and heated to 80 ℃, then 0.06g of phenothiazine is added, stirring and dispersing are uniformly carried out, then 0.40g of trimethyl hydroxyethyl ammonium catalyst and 0.10g of imidazole are added for trimerization reaction until the conversion rate of the 3-isopropyl-dimethylbenzyl isocyanate reaches 35%, 0.2g of dioctyl phosphate is added for stopping the reaction, thus obtaining an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are further removed through thin film distillation under the conditions of 150 ℃ and vacuum degree of <500 Pa. According to analysis, the NCO content was 18.9%, the viscosity was 3798cP/25℃and the ratio of isocyanurate mononuclear structure (I)/structure (II) was 11.2%, the sum of the monomer contents of hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate in the free state was 0.12%, and the thermal storage stability of the polyisocyanate composition was evaluated to be excellent.

Comparative example 1

Comparative example 1 differs from example 4 above only in that the product having dual curing properties prepared without diisocyanate monomer contains only structure II and not structure I.

The preparation method of the polyisocyanate composition of the comparative example comprises the steps of weighing 500g of hexamethylene diisocyanate trimer (HT-100) and 100g of 3-isopropyl-dimethylbenzyl isocyanate in a reaction vessel under an inert gas atmosphere, heating to 80 ℃ and directly blending and modifying, and then adding 0.06g of phenothiazine, stirring and dispersing uniformly to ensure that the composition meets the dual-curing characteristic. The heat storage stability of the polyisocyanate composition was evaluated as poor by analysis of an NCO content of 21.8%, a viscosity of 489cP/25℃and an isocyanurate mononuclear structure (I)/structure (II) ratio of 0.

Comparative example 2

The difference compared with example 2 is only that the addition amount of 3-isopropyl-dimethylbenzyl isocyanate is increased.

The preparation method of the polyisocyanate composition of the comparative example comprises the steps of weighing 500g of hexamethylene diisocyanate and 700g of 3-isopropyl-dimethylbenzyl isocyanate respectively in a reaction vessel under an inert gas atmosphere, heating to 60 ℃, adding 0.09g of phenothiazine, stirring and dispersing uniformly, adding 0.32g of tetrabutylammonium hydroxide catalyst and 0.35g of imidazole for trimerization until the conversion rate of the 3-isopropyl-dimethylbenzyl isocyanate reaches 50%, adding 0.2g of dibutyl phosphate for terminating the reaction to obtain an isocyanate mixture solution, and further removing unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate by thin film distillation under the conditions of 150 ℃ and vacuum degree of <500 Pa. According to analysis, the isocyanate composition had an NCO content of 12.2%, a viscosity of 8691cP/25℃and an isocyanurate mononuclear body structure (I)/structure (II) ratio of 65.7%, and a sum of monomer contents of hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate in a free state of 0.22%, and the heat storage stability was evaluated as good.

Comparative example 3

The difference compared with example 4 is only that the addition amount of 3-isopropyl-dimethylbenzyl isocyanate is reduced.

Under inert gas atmosphere, 500g of hexamethylene diisocyanate and 30g of 3-isopropyl-dimethylbenzyl isocyanate are respectively weighed into a reaction vessel and heated to 80 ℃, then 0.06g of phenothiazine is added, stirring and dispersing are uniformly carried out, then 0.40g of trimethyl hydroxyethyl ammonium catalyst and 0.10g of imidazole are added for trimerization reaction until the conversion rate of the 3-isopropyl-dimethylbenzyl isocyanate reaches 35%, 0.2g of dioctyl phosphate is added for stopping the reaction, thus obtaining an isocyanate mixture solution, and unreacted hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate are further removed through thin film distillation under the conditions of 150 ℃ and vacuum degree of <500 Pa. According to analysis, the NCO content was 19.8%, the viscosity was 3489cP/25℃and the ratio of isocyanurate mononuclear structure (I)/structure (II) was 2.8%, the sum of the monomer contents of hexamethylene diisocyanate and 3-isopropyl-dimethylbenzyl isocyanate in the free state was 0.11%, and the thermal storage stability of the polyisocyanate composition was evaluated to be excellent.

Examples of applications of the polyisocyanate composition.

The UV-thermosetting two-component coating is prepared by taking the polyisocyanate composition as a raw material, respectively adding 50 parts of hydroxy acrylic resin AC-1260, 45 parts of butyl acetate and 5 parts of trimethylolpropane triacrylate into a batching container under the condition that the relative humidity is lower than 40% at 25 ℃, mechanically stirring and mixing uniformly, adding the prepared polyisocyanate composition according to the metering of NCO/OH ratio of 1.05 after the photoinitiator UV-1173 is 150ppm based on the total mass and BYK306 is 50ppm, mechanically stirring for 5mins to uniformly mix, vacuumizing at room temperature, and removing bubbles to obtain the UV-thermal dual-curable polyurethane coating.

The obtained coating composition is respectively and evenly sprayed on a circuit board or a PET film and in a tetrafluoroethylene mold, and is placed in an ultraviolet curing machine for curing for 10 seconds, and the main wavelength of the ultraviolet curing machine used for experiments is 365nm, and the power density is 60W/cm ². And after the UV curing is finished, placing the test sample in an environment at 50 ℃ for 3 hours to realize complete curing, and then obtaining the test sample for performance testing.

(1) The tack-free time was tested according to GB/T1728-2020.

(2) And (3) testing high-temperature and high-humidity hydrolysis resistance, namely cutting a test sample into a sheet with 15mm and 200mm, putting the sheet into a pressure cooker, treating the sheet for 25 hours at the temperature of 120 ℃ and the high-temperature and high-pressure environment with the pressure of 0.1Mpa, taking out the sheet, aging the sheet for 1 day in the room-temperature environment, and using a tensile strength tester to conduct 180-degree peeling test at the test speed of 50 mm/min.

The evaluation standard is that the peeling strength is more than or equal to 10N/15 mm;

the peeling strength is not more than 6N/15mm and not more than 10N/15 mm;

Peel strength is less than or equal to 1N/15mm and less than or equal to 6N/15 mm;

(3) Weather resistance test, namely cutting a test sample into 50 mm-150 mm sheets, performing an accelerated aging test on the composite layer by using a xenon lamp weather resistance tester, and observing the appearance after illumination aging according to the ASTM G155 standard.

The evaluation standard is that no change is optimal;

slight discoloration or cracking is good;

Obvious discoloration or poor cracking occurs;

(4) And (3) testing the humidity-resistant aging performance, namely cutting a test sample into 15mm or 200mm slices, putting the slices into a high-temperature high-humidity test box, wherein the test conditions are that the humidity is 85%, the temperature is 85 ℃ and the time is 1000 hours, testing the humidity-resistant aging performance, observing whether the appearance coating is chalking, bubbles and the like, and meanwhile, testing the adhesive force by a cross-cut method, wherein more than 95% of the slices are qualified without falling, and the rest conditions are unqualified.

The results of the performance test of the paint chips prepared from the polyisocyanate compositions obtained in examples and comparative examples are shown in Table 1.

Table 1 test sample performance test results for the preparation of the example and comparative polyisocyanate

As can be seen from the macroscopic indexes of the polyisocyanate compositions prepared in examples 1 to 4 and comparative examples 1 to 3 and the performance test results of the products of Table 1, the polyisocyanate compositions prepared in examples 1 to 4 have relatively low viscosity and excellent thermal storage stability, and the prepared test pieces are excellent in both performance indexes such as hydrolysis resistance and wet heat aging resistance at high temperature and high humidity and have the advantage of short tack-free time, while the polyisocyanates prepared in comparative examples 1 to 4 cannot simultaneously satisfy the conditions of low viscosity and excellent comprehensive performance of the products, so that the actual demands are difficult to satisfy.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims (8)

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 compound with a carbon number between _C4 and _C30 , which has two terminal isocyanate groups and the isocyanate groups are not directly connected to a benzene ring, 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 described in any one of claims 1 to 3, or the composition prepared by the preparation method described in claim 4 or 5, or the curing agent prepared by the preparation method described in claim 7, characterized in that the coating adopts the polyisocyanate composition as the curing agent component.