Storage-stable polyisocyanate composition and storage method of polyisocyanate composition

Abstract

The invention provides a polyisocyanate composition with stable storage and application thereof. The polyisocyanate composition is a polyisocyanate mixture containing structures such as isocyanurate, carbamate, allophanate, biuret, iminooxadiazinedione, uretdione, carbodiimide, uretonimine and the like, and is prepared by the following steps: carrying out separation treatment by using an evaporator to remove an unreacted isocyanate monomer; and diluting the separated heavy component with a solvent or not, and packaging to obtain the product. Wherein the mass fraction content of carbon dioxide in the gas phase of the residual space of the packaging product is 0.03-2%, and the obtained polyisocyanate product is stable in storage transparency.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing isocyanate derivatives, and particularly relates to a preparation method of a storage-stable polyisocyanate composition, a polyisocyanate composition prepared therefrom, and applications thereof. Background Art

[0002] As is well known, polyurethane resin coatings have excellent abrasion resistance, chemical resistance, and stain resistance. In particular, polyisocyanates derived from aliphatic (cyclic) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate also have excellent weather resistance in the polyurethane resin coatings prepared therefrom. Therefore, these polyisocyanates are often used in the coating of buildings, automobiles, airplanes, ships, and cross-sea bridges and their repair coatings in the form of room-temperature or heat-cured polyurethane coatings.

[0003] Currently, methods for preparing polyisocyanates from aromatic, aliphatic, or cycloaliphatic diisocyanate monomers in the presence of a catalyst are known, and the advantages and disadvantages of various catalyst systems have been discussed in detail in the literature, such as J.Prakt.Chem. 336 (1994) 185-200, CN201410002995.5, CN95113103.6, CN200310120368.3, CN200310120121.1, CN200910128728.1, CN201280059016.9.

[0004] However, the main disadvantage of polyisocyanates prepared by existing processes is that the turbidity increases relatively fast during storage, further affecting the gloss of downstream paint film products and the transparency of cast elastomers. Therefore, it is of great significance to study polyisocyanate compositions with improved storage transparency stability. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a storage-stable polyisocyanate composition. The method is simple to operate, and without using any additives, a polyisocyanate composition with stable storage transparency performance (turbidity) is obtained, effectively solving the application problems caused by unstable transparency during the storage and downstream customer use of polyisocyanates prepared by existing methods.

[0006] To achieve the above object, the technical solutions provided by the present invention are as follows:

[0007] A polyisocyanate composition with stable turbidity storage, wherein the mass fraction of carbon dioxide in the gas phase of the residual space of the packaged product is 0.03-2%, and the rest is nitrogen.

[0008] A preparation method of a polyisocyanate composition with stable turbidity storage, comprising:

[0009] S1: The reaction of isocyanate monomers with polyols, or the self-polymerization reaction of isocyanates;

[0010] S2: Optionally add a terminator after reaching the conversion rate to end the reaction and obtain a polyisocyanate reaction solution;

[0011] S3: Optionally subject the polyisocyanate reaction solution obtained in S2 to separation treatment through an evaporator to obtain separated heavy components;

[0012] S4: Optionally dilute the separated heavy components obtained in S3 with a solvent and package them to obtain the product. Some isocyanate compositions are directly packaged to obtain the product without going through the S3 step.

[0013] By controlling the mass fraction of carbon dioxide in the gas phase space of the packaged product to be 0.03 - 2%, the turbidity stability of the finally obtained product is greatly improved. The product is stored at 25°C for 12 months, and the transparency basically does not decrease; research shows that it may be that the water introduced during the solvent and packaging process reacts with carbon dioxide to form acidic substances. If the carbon dioxide content is too high, the acidity of the product is obvious, and the acidic substances further catalyze the reaction of isocyanate groups with water. Since there are no dispersion measures such as stirring in the packaging barrel, solid small particles are locally generated, and the apparent test index is an increase in the turbidity of the product; further research shows that the acidic substances generated by a small amount of carbon dioxide will combine with the residual trace catalyst in the product and the complex formed by the catalyst and the terminator to form a more neutral complex, thus avoiding the further self-polymerization of isocyanate groups. The gas phase space in the packaged product refers to the remaining volume in the container after filling the polyisocyanate composition product into the container. Generally, the remaining volume accounts for 2 - 20% of the total volume of the packaging content.

[0014] According to the preparation method provided by the present invention, the preparation method of the isocyanate monomer used as the raw material for preparing the polyisocyanate reaction solution is not important for the implementation of the preparation method of the present invention, including isocyanate monomers that can be produced using, without using phosgene or any other method. For example, aromatic, aliphatic, and / or alicyclic organic isocyanates, which are organic diisocyanates or organic polyisocyanates containing 4 - 20 carbon atoms in the carbon skeleton in addition to the NCO group;

[0015] In some examples, the isocyanate monomer is selected from one or more of aromatic organic isocyanates, aliphatic organic isocyanates, and alicyclic organic isocyanates, preferably selected from one or more of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), cyclohexyl dimethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), dicyclohexylmethane diisocyanate (HXDI), norbornane dimethylene diisocyanate (NBDI), cyclohexyl diisocyanate (CHDI), lysine diisocyanate (LDI), tetramethylxylylene diisocyanate (TMXDI), 2,4,4-trimethylhexane diisocyanate (TMHDI), toluene diisocyanate (TDI), methylcyclohexyl diisocyanate (HTDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), diphenylmethane diisocyanate (MDI), and polymethylene polyphenyl polyisocyanate (PM).

[0016] According to the preparation method provided by the present invention, the preparation process of the polyisocyanate reaction liquid is a prior art. The polyisocyanate reaction liquid applicable to the method of the present invention can be a polyisocyanate reaction liquid prepared by any method, and the present invention does not make specific limitations. The "achieving conversion rate" can be understood as the conversion rate preset according to the product to be prepared as required. For different types of polyisocyanate products, the required conversion rates are different, which is well known to those skilled in the art and will not be elaborated here.

[0017] According to the preparation method provided by the present invention, in a specific embodiment, the total content of polyisocyanate in the polyisocyanate reaction liquid is 5-80 wt% (for example, 10, 20, 30, 40, 50, 60, 70 wt%, etc.), preferably 20-70 wt%, including polyisocyanates containing one or more of isocyanurate structure, urethane structure, urethane structure, biuret structure, iminooxadiazinedione structure, uretoneimine structure, carbodiimide structure, and allophanate structure. For example, the reaction liquid includes: polyisocyanates containing isocyanurate structure, polyisocyanates containing urethane structure, polyisocyanates containing biuret structure, polyisocyanates containing uretoneimine structure, and so on.

[0018] According to the preparation method provided by the present invention, in some examples, the polyisocyanate reaction liquid includes a trimer polyisocyanate reaction liquid, a polyisocyanate reaction liquid containing a biuret structure, and a polyisocyanate reaction liquid containing a uretoneimine structure.

[0019] According to the preparation method provided by the present invention, separating and treating the polyisocyanate reaction liquid through an evaporator is a conventional operation in the art, and the present invention does not make specific limitations. In some examples, the evaporator used is a scraping evaporator, preferably a thin-film evaporator (including a thin-film evaporator and a short-path evaporator), which includes a rotor with a scraper and an evaporator cylinder part with a heating jacket. The material to be separated passes through a disperser arranged at the upper part of the evaporator and is evenly dispersed on the inner wall of the evaporator cylinder. The material flows downward naturally by gravity. The rotor with a scraper rotates at a constant speed to scrape the material into a thin liquid film. The low-boiling free monomers escape from the liquid film, and the unvolatile heavy components and a small amount of residual free monomers enter the next separation device. The evaporator cylinder part with a heating jacket is heated by heated heat-conducting oil or steam to provide heat for the material to be separated;

[0020] Preferably, the evaporator is used alone at the first stage and / or used in series at the second stage;

[0021] Preferably, the separation temperature of the evaporator is 100 - 200 °C, and the pressure is 5 - 200 PaA.

[0022] In the present invention, for different types of polyisocyanate reaction liquids, their preparation methods may be different;

[0023] In the first embodiment, the preparation method of the trimeric polyisocyanate composition includes the following steps:

[0024] (11) Under an inert atmosphere, add the isocyanate monomer to a reaction vessel and heat it. After the system is heated to the reaction temperature, add (for example, dropwise add) catalyst I and carry out a polymerization reaction, and track and measure the NCO% of the reaction liquid; when the NCO% value drops to an appropriate value (for example, 30 - 70%), add terminator I to terminate the reaction to obtain a trimeric polyisocyanate reaction liquid;

[0025] (12) Then, separate and treat the trimeric polyisocyanate reaction liquid through a separation device (for example, a combination of a thin-film evaporator and a short-path evaporator) to obtain a heavy component, that is, a trimeric polyisocyanate composition;

[0026] For example, in the trimeric polyisocyanate reaction liquid, it includes a polyisocyanate containing one or more of an isocyanurate structure, a urethane structure, a urethane carbamate structure, an iminooxadiazinedione structure, a uretdione structure, a carbodiimide structure, and a uretonimine structure, preferably a polyisocyanate containing an isocyanurate structure, a urethane structure, a urethane carbamate structure, an iminooxadiazinedione structure, a uretdione structure, a carbodiimide structure, and a uretonimine structure;

[0027] In some examples, the catalyst I in step (11) is a quaternary ammonium base and / or quaternary ammonium salt catalyst, preferably selected from choline hydroxide, trimethylhydroxyethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, 1-adamantylammonium hydroxide, hexamethonium hydroxide, organic weak acid salts of tetraalkylammonium (such as tetramethylammonium, tetraethylammonium, etc.) (such as formic acid, acetic acid, capric acid, etc.), tetraethyloctanoate ammonium, organic weak acid salts of trimethylhydroxypropylammonium (such as formic acid, acetic acid, capric acid, etc.), and organic weak acid salts of trimethylhydroxyethylammonium (such as formic acid, acetic acid, capric acid, etc.);

[0028] The organic weak acid salts of tetraalkylammonium described here can be ammonium tetramethylformate, ammonium tetramethylacetate, ammonium tetramethyldecanoate, ammonium tetraethylformate, ammonium tetraethylacetate, ammonium tetraethyldecanoate; the organic weak acid salts of trimethylhydroxypropylammonium can be ammonium trimethylhydroxypropylformate, ammonium trimethylhydroxypropylacetate, ammonium trimethylhydroxypropyldecanoate; the organic weak acid salts of trimethylhydroxyethylammonium can be ammonium trimethylhydroxyethylformate, ammonium trimethylhydroxyethylacetate, ammonium trimethylhydroxyethyldecanoate;

[0029] In some examples, the addition amount of the catalyst I is 0.001 wt% - 0.1 wt% of the weight of the isocyanate monomer (such as 0.0025 wt%, 0.005 wt%, 0.01 wt%, 0.04 wt%, 0.06 wt%, 0.08 wt%);

[0030] The catalyst I can be used as a pure substance or optionally dissolved in an alcohol at any concentration. As a diluent for the catalyst, the alcohol can be, but is not limited to, monohydric alcohols and / or dihydric alcohols; preferably, the monohydric alcohol is selected from one or more of C1-C10 aliphatic alcohols, araliphatic alcohols, aromatic alcohols, aliphatic phenols, araliphatic phenols, and aromatic phenols, and more preferably exists in the form of a straight-chain, branched-chain, or cyclic alcohol or phenol. The dihydric alcohol can be, but is not limited to, the following, for example, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, and 2,2-diethyl-1,3-propanediol;

[0031] In some examples, the terminator I described in step (11) is selected from organic acids and / or acylating agents, preferably one or more selected from formic acid, benzoic acid, benzoyl chloride, dibutyl phosphate, and bis(2-ethylhexyl) phosphate;

[0032] Those skilled in the art can understand that different types of polymerization catalysts used in the reaction system will result in different amounts of terminator. In the reaction system of the present invention, the addition amount of the terminator I is based on deactivating the polymerization catalyst I in the system;

[0033] In some examples, the reaction temperature of step (11) is 30 - 100 °C (for example, 35 °C, 50 °C, 60 °C, 70 °C, 90 °C), preferably 40 - 80 °C;

[0034] In some examples, the separation device described in step (12) is a first-stage wiped-film evaporator; the wiping system of the wiped-film evaporator can be a roller type or a scraping type, and the evaporator can be a thin-film evaporator or a short-path evaporator. The process conditions for the separation treatment include: the separation temperature of the first-stage wiped-film evaporator is 140 - 180 °C (for example, 140 °C, 160 °C, 180 °C), and the absolute separation pressure is 5 - 200 Pa (for example, 5 Pa, 10 Pa, 50 Pa, 100 Pa, 200 Pa);

[0035] For example, in the resulting heavy-component polyisocyanate trimer composition after the separation treatment, the residual monomer content is less than or equal to 0.1 wt% based on the mass of the composition.

[0036] In the second embodiment, a method for preparing an isocyanate prepolymer includes the following steps:

[0037] (21) Under nitrogen protection, add the isocyanate to the reaction kettle, continuously add the polyether polyol to the reaction kettle at the reaction temperature. After the dropping is completed, add the catalyst and continue the reaction;

[0038] (22) After reaching an appropriate conversion rate, add 40% - 85% of the alicyclic diisocyanate based on the total mass of the isocyanate prepolymer, stir evenly, and cool to room temperature to obtain the product;

[0039] In the described method, the isocyanate is selected from aliphatic polyisocyanates, such as hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, or their corresponding oligomers or any mixture thereof, preferably isophorone diisocyanate or dicyclohexylmethane diisocyanate or methylcyclohexyl diisocyanate;

[0040] In the method described above, the polyether polyol is polypropylene oxide ether polyol, polyethylene oxide ether polyol, polypropylene oxide-ethylene oxide ether polyol or any mixture thereof; preferably polypropylene oxide ether polyol or polypropylene oxide-ethylene oxide ether polyol, and more preferably polypropylene oxide ether polyol. The initiator used for the polyether polyol can be a diol such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol; a triol such as trimethylolpropane, glycerol, castor oil; a tetraol such as pentaerythritol, ethylenediamine. The polyether polyol has a molecular weight of 200-1000 daltons, an average functionality of 2.5-6, and a hydroxyl value of 100-800 mgKOH / g;

[0041] In the method described above, the alicyclic diisocyanate can be selected from isophorone diisocyanate, dicyclohexylmethane diisocyanate or methylcyclohexyl diisocyanate and any mixture thereof, preferably isophorone diisocyanate or dicyclohexylmethane diisocyanate;

[0042] In the present invention, 40%-85% of alicyclic diisocyanate based on the total mass of the isocyanate prepolymer is added, preferably 50-70% of dicyclohexylmethane diisocyanate;

[0043] In the isocyanate prepolymer of the present invention, the content of free isocyanate groups is 15-32%, preferably 21-32%, and more preferably 23-28%.

[0044] In the method of the present invention, the catalyst is selected from one or more of dibutyltin dilaurate, stannous octoate, iron acetylacetonate, zinc octoate, lead octoate, potassium oleate; more preferably dibutyltin dilaurate or stannous octoate; the addition amount is 0.01-0.06% based on the total mass of the reaction system.

[0045] The present invention also relates to a storage method for a polyisocyanate composition. The polyisocyanate composition is stored in a container, and nitrogen is used to displace the gas phase space of the packaged product, and carbon dioxide is supplemented at the same time. Among them, the mass fraction of carbon dioxide in the gas phase space of the packaged product is controlled at 0.03-2%. This storage method can keep the turbidity of the polyisocyanate composition stable during storage.

[0046] Another object of the present invention is also to provide the application of the polyisocyanate composition with stable turbidity storage or the polyisocyanate composition with stable turbidity storage prepared by the preparation method. The polyisocyanate composition can be used to prepare other related products such as polyurethane coatings and polyurethane adhesives after being blocked by a blocking agent.

[0047] In some examples, the polyisocyanate product is applied to various additive systems and various isocyanate raw material systems, and is preferably applied in the fields of oil-based polyurethane paints, water-based polyurethane materials, and yellowing-resistant polyurethane materials.

[0048] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0049] In the process of preparing the polyisocyanate composition of the present invention, by controlling the carbon dioxide content in the gas phase space of the packaged product to be 0.03-2%, a polyisocyanate composition product with excellent storage stability is obtained. The product is stored at 25°C for 12 months, and the product transparency remains stable (the apparent test index is that the turbidity does not increase). Detailed implementation manners

[0050] To better understand the technical solution of the present invention, the content of the present invention will be further elaborated below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments only.

[0051] Test methods:

[0052] (1) Determination of the content of free isocyanate monomer:

[0053] Gel chromatography technology (LC-20AD / RID-10A, the chromatographic column is MZ-Gel SD plus10E3A, 5μm (8.0*300mm), MZ-Gel SDplus 500A 5μm (8.0*300mm), MZ-Gel SDplus100A5μm (8.0*300mm) in series, Shimadzu; mobile phase: tetrahydrofuran; flow rate: 1.0 mL / min; analysis time: 40 min, chromatographic column temperature: 35°C) is used for the quantification of isocyanate raw materials. The areas of polymers and monomers in the system to be tested are determined by the area normalization method. The isocyanate monomer content (%) = S (isocyanate monomer peak area) / S (sum of the peak areas of each component) * 100%.

[0054] (2) NCO% content test, referring to the standard GB / T 12009.4;

[0055] (3) Turbidity: The turbidity can be obtained by testing with a HACH 2100N;

[0056] (4) Test conditions for carbon dioxide in the air:

[0057] 1. Instrument configuration:

[0058] The instrument is a system gas chromatograph composed of a ten-port valve (sampling and backflushing function), a six-port valve (isolation valve), three chromatographic analysis columns (2 P-Ns, one MS-13X), and a TCD detector.

[0059] 2. Method setting (reference):

[0060]

[0061] 3. Quantitative method

[0062] A mixed gas composed of 79.06% nitrogen (mass content), 20.90% oxygen (mass content), and 0.04% carbon dioxide (mass content) is used as the standard sample. The external standard method is used to determine the oxygen and carbon dioxide contents in the sample. The sample is measured three times, and the average value of the measurements is taken as the final result.

[0063] In the following examples and comparative examples, the chemical raw material information used is as follows. Unless otherwise specified, all others are ordinary commercially available raw materials:

[0064] 1,6 - Hexamethylene diisocyanate ( HDI), Wanhua Chemical ;

[0065] Dicyclohexylmethane diisocyanate ( HMDI), Wanhua Chemical ;

[0066] Polyether polyol (Wanol R2307), Wanhua Chemical;

[0067] 2 - Ethyl - 1,3 - hexanediol, purity ≥ 99%, Sigma - Aldrich;

[0068] Tetraethylammonium hydroxide solution (concentration 25 wt%, methanol solution), Sigma - Aldrich;

[0069] Bis(2 - ethylhexyl) phosphate: purity > 98.5%, Aladdin reagent.

[0070] Dibutyltin dilaurate: purity > 98.5%, Aladdin reagent.

[0071] In the following examples and comparative examples, unless otherwise specified, during the process from before the reaction to the addition of the catalyst and throughout the reaction, the reaction solution is kept under dry nitrogen protection. Unless otherwise stated, all percentages in the text are mass percentages.

[0072] Product preparation example 1

[0073] (1) Add 20,000 kg of hexamethylene diisocyanate (abbreviated as HDI) into the reaction device and heat it to 70 °C. Add 10 kg of tetraethylammonium hydroxide solution (concentration 25 wt%, methanol solution), carry out the polymerization reaction, and track and measure the NCO% of the reaction solution; when the NCO content rate in the reaction solution reaches 40 wt%, add 3.2 kg of bis(2-ethylhexyl) phosphate to terminate the reaction, and obtain the HDI trimer polyisocyanate reaction solution.

[0074] (2) Pass the reaction solution through a two-stage series evaporator for separation treatment. Among them, the separation temperature of the first-stage thin-film evaporator is 155 ± 2.5 °C, the separation vacuum degree is 100 Pa absolute pressure, the separation temperature of the second-stage short-path evaporator is 155 ± 2.5 °C, and the separation vacuum degree is 20 Pa absolute pressure, to remove the unreacted isocyanate monomer and obtain the heavy component, namely the HDI trimer polyisocyanate composition.

[0075] Test the prepared polyisocyanate composition, its turbidity is 0.18 NTU, and the residual HDI monomer content is 0.08 wt%.

[0076] Product Preparation Example 2

[0077] Under nitrogen protection, add 3,200 kg of hexamethylene diisocyanate into the reaction kettle, heat and stir in an 80 °C oil bath. When the system temperature reaches 80 °C, add 3,500 kg of polyether polyol Wanol R2307 dropwise into the reaction kettle. After the dropping is completed, add 0.02% of dibutyltin dilaurate based on the total mass of the reaction system, and make the reaction system continue to stir and react at 80 °C for 2 h. Then add 10,000 kg of dicyclohexylmethane diisocyanate and stir evenly. The final NCO content of the prepolymer product is 25.0%, and the turbidity is 0.25 NTU.

[0078]

Application Example

[0079] Fill the product prepared in the above product preparation example into 200 L stainless steel barrels through a filling machine. The filling volume of each barrel is 190 L. Use nitrogen to displace the gas phase space of the packaged product, and at the same time supplement the corresponding amount of carbon dioxide according to the following examples. The experimental results are shown in Table 1:

[0080] Table 1. Experimental Results

[0081]

[0082] Those skilled in the art can understand that under the teaching of this specification, some modifications or adjustments can be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A polyisocyanate composition with stable turbidity storage, wherein, The mass fraction content of carbon dioxide in the gas phase of the residual space of the packaged product is 0.03 - 2%.

2. The polyisocyanate composition according to claim 1, characterized in that, The preparation method includes: S1: Reacting an isocyanate monomer with a polyol, or self-polymerizing an isocyanate; S2: Optionally adding a terminator after reaching the conversion rate to end the reaction and obtain a polyisocyanate reaction solution; S3: Optionally subjecting the polyisocyanate reaction solution obtained in S2 to separation treatment by an evaporator to obtain a separated heavy component; S4: Optionally diluting the separated heavy component obtained in S3 with a solvent, packaging to obtain a product.

3. The polyisocyanate composition according to claim 2, characterized in that, The isocyanate monomer described in S1 is selected from one or more of aromatic organic isocyanates, aliphatic organic isocyanates, and alicyclic organic isocyanates, preferably one or more of hexamethylene diisocyanate, isophorone diisocyanate, cyclohexyl dimethylene diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, norbornane dimethylene diisocyanate, cyclohexyl diisocyanate, lysine diisocyanate, tetramethyl xylylene diisocyanate, 2,4,4-trimethylhexane diisocyanate, toluene diisocyanate, methylcyclohexyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate.

4. The polyisocyanate composition according to claim 2, characterized in that, The total content of polyisocyanate in the polyisocyanate reaction solution described in S2 is 5 - 80 wt%, preferably 20 - 70 wt%; The polyisocyanate reaction solution contains a polyisocyanate having one or more structures among an isocyanurate structure, a urethane structure, a urethane structure, a biuret structure, an iminooxadiazinedione structure, a uretdione structure, a carbodiimide structure, and a uretonimine structure.

5. The polyisocyanate composition according to claim 2, wherein The polyisocyanate reaction solution is subjected to separation treatment by an evaporator, and the evaporator is a wiped film evaporator; Preferably, the wiped film evaporator is a thin film evaporator and / or a short path evaporator.

6. The polyisocyanate composition according to claim 5, characterized in that, The separation temperature of the evaporator is 100 - 200 °C; And / or, the separation pressure of the evaporator is an absolute pressure of 5 - 200 Pa.

7. Use of the polyisocyanate composition according to any one of claims 1 - 6, the polyisocyanate composition is used for preparing polyurethane coatings, polyurethane adhesives and related products after being blocked by a blocking agent.

8. A storage method for a polyisocyanate composition, where the polyisocyanate composition is stored in a container, and nitrogen is used to displace the gas phase space of the packaged product while carbon dioxide is supplemented. Among them, The mass fraction of carbon dioxide in the gas phase space of the packaged product is controlled at 0.03 - 2%.

9. The storage method according to claim 8, wherein, The preparation method of the polyisocyanate composition includes: S1: Reacting an isocyanate monomer with a polyol, or self-polymerizing an isocyanate; S2: Optionally adding a terminator after reaching the conversion rate to end the reaction and obtain a polyisocyanate reaction solution; S3: Optionally subjecting the polyisocyanate reaction solution obtained in S2 to separation treatment by an evaporator to obtain a separated heavy component; S4: Optionally diluting the separated heavy component obtained in S3 with a solvent and packaging.

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