Storage-stable 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, imino oxadiazinedione, uretdione, carbodiimide, uretonimine and the like which are obtained by self-polymerization of an isocyanate monomer under the action of a catalyst or reaction of the isocyanate monomer with alcohol and water, and the polyisocyanate composition is prepared from the polyisocyanate mixture containing structures such as isocyanurate, carbamate, allophanate, biuret, imino oxadiazinedione, uretdione, carbodiimide, uretonimine and the like. Carrying out separation treatment through an evaporator to remove unreacted isocyanate monomers, diluting heavy components obtained through separation through a solvent or not, and packaging to obtain a product; wherein the volume fraction content of oxygen in the gas phase of the residual space of the packaging product is 0.5-25%, and the storage viscosity of the obtained polyisocyanate product is stable.

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 are used to prepare polyurethane resin coatings with excellent weather resistance. Therefore, these polyisocyanates are often used in the form of room-temperature or heat-cured polyurethane coatings for the painting of buildings, automobiles, airplanes, ships, and cross-sea bridges, as well as for repair 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 viscosity increases rapidly during storage, seriously affecting long-distance transportation and downstream use. Therefore, it is of great significance to study how to obtain a storage-stable polyisocyanate composition without using any additives. Summary of the Invention

[0005] In view of the above problems in the prior art, the present invention provides a storage-stable polyisocyanate composition and a preparation method thereof. The method is simple to operate, and a polyisocyanate composition with stable viscosity during storage can be obtained without using any additives, effectively solving the problem of unstable viscosity during the storage and downstream 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 storage-stable polyisocyanate composition, wherein the volume fraction content of oxygen in the gas phase of the residual space of the packaged product is 0.5 - 25%, and the rest is nitrogen.

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

[0009] S1: The isocyanate monomer reacts with the polyol, or the isocyanate polymerizes itself;

[0010] S2: After reaching the conversion rate, a terminator is added or not added to end the reaction, obtaining a polyisocyanate reaction solution;

[0011] S3: Optionally, the polyisocyanate reaction solution obtained in S2 is separated and treated through an evaporator;

[0012] S4: The finally separated and recombined fraction obtained in S3 is diluted with a solvent or not diluted with a solvent, and then packaged to obtain the product. Some isocyanate compositions are directly packaged without going through the S3 step to obtain the product.

[0013] We surprisingly found that by controlling the volume fraction of oxygen gas in the gas phase space of the packaged product to be 0.5 - 25%, the stability of the finally obtained product is greatly improved; further research shows that it may be that the presence of oxygen can react with the trace residual additives in the product, reducing the catalytic activity of the residual additives and avoiding further polymerization of the product. If the oxygen content is too high, it will cause an increase in the color number of the product, thereby causing the product to deteriorate. 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. Based on this, we completed the present invention.

[0014] According to the preparation method provided by the present invention, the preparation process of the polyisocyanate reaction solution is a prior art. The polyisocyanate reaction solution applicable to the method of the present invention can be a polyisocyanate reaction solution prepared by any method, and the present invention does not make specific limitations. For example, in the specific implementation manner, the preparation method that the polyisocyanate reaction solution can adopt is:

[0015] S1: The isocyanate monomer reacts with the polyol, or the isocyanate polymerizes itself;

[0016] S2: After reaching the conversion rate, a terminator is added or not added to end the reaction, obtaining a polyisocyanate reaction solution;

[0017] Among them,

[0018] Here, the so-called "reaching the conversion rate" can be understood as the conversion rate preset according to the product to be prepared. For different types of polyisocyanate products, the required conversion rates are different, which are well known to those skilled in the art and will not be elaborated here.

[0019] According to the preparation method provided by the present invention, in a specific embodiment, the total content of polyisocyanate in the polyisocyanate reaction solution is 5-80 wt% (for example, 10, 20, 30, 40, 50, 60, 70 wt%), preferably 20-70 wt%, and includes polyisocyanates containing one or more of isocyanurate structure, urethane structure, urethane structure, biuret structure, iminooxadiazinedione structure, uretidione structure, carbodiimide structure and uretonimine structure. For example, the reaction solution includes: polyisocyanate containing isocyanurate structure, polyisocyanate containing urethane structure, polyisocyanate containing biuret structure, polyisocyanate containing uretidione structure, and so on.

[0020] According to the preparation method provided by the present invention, in some examples, the polyisocyanate reaction solution includes a trimer polyisocyanate reaction solution, a polyisocyanate reaction solution containing a biuret structure, and a polyisocyanate reaction solution containing a uretidione structure.

[0021] According to the preparation method provided by the present invention, separating the polyisocyanate reaction solution 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 wiped 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 naturally downward by gravity. The rotor with a scraper rotates at a constant speed to scrape the material into a thin liquid film. Low-boiling free monomers escape from the liquid film, and the unevaporated 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 transfer oil or steam to provide heat for the material to be separated;

[0022] Preferably, the evaporator is used alone at the first stage and / or used in series at the second stage, preferably used alone at the first stage;

[0023] Preferably, the separation temperature of the evaporator is 100-200 °C, and the pressure is 5-200 PaA.

[0024] 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, and includes isocyanate monomers that can be produced using phosgene, 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;

[0025] 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).

[0026] In the present invention, the preparation methods of different types of polyisocyanate reaction liquids can be different.

[0027] In the first embodiment, the preparation method of the trimer polyisocyanate reaction liquid includes the following steps:

[0028] (11) Under an inert atmosphere, add the isocyanate monomer to the 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 the trimer polyisocyanate reaction liquid;

[0029] (12) Then, separate the trimer 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, namely the trimer polyisocyanate composition;

[0030] For example, in the trimer polyisocyanate reaction liquid, it includes polyisocyanates containing one or more of isocyanurate structures, urethane structures, urethane structures, iminooxadiazinedione structures, uretidione structures, carbodiimide structures, and uretonimine structures, preferably polyisocyanates containing isocyanurate structures, urethane structures, urethane structures, iminooxadiazinedione structures, uretidione structures, carbodiimide structures, and uretonimine structures;

[0031] In some examples, the catalyst I in step (11) is a quaternary ammonium base and / or a 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 (e.g., tetramethylammonium, tetraethylammonium, etc.) (e.g., formic acid, acetic acid, capric acid, etc.), ammonium tetramethylcaprylate, organic weak acid salts of trimethylhydroxypropylammonium (e.g., formic acid, acetic acid, capric acid, etc.), and organic weak acid salts of trimethylhydroxyethylammonium (e.g., formic acid, acetic acid, capric acid, etc.);

[0032] The organic weak acid salts of tetraalkylammonium described herein may be ammonium tetramethylformate, ammonium tetramethylacetate, ammonium tetramethyldecanoate, ammonium tetraethylformate, ammonium tetraethylacetate, ammonium tetraethyldecanoate; the organic weak acid salts of trimethylhydroxypropylammonium may be ammonium trimethylhydroxypropylformate, ammonium trimethylhydroxypropylacetate, ammonium trimethylhydroxypropylcaprylate; and the organic weak acid salts of trimethylhydroxyethylammonium may be ammonium trimethylhydroxyethylformate, ammonium trimethylhydroxyethylacetate, ammonium trimethylhydroxyethylcaprylate;

[0033] In some examples, the addition amount of the catalyst I is 0.001 wt% - 0.1 wt% of the weight of the isocyanate monomer (e.g., 0.0025 wt%, 0.005 wt%, 0.01 wt%, 0.04 wt%, 0.06 wt%, 0.08 wt%);

[0034] 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 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 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;

[0035] In some examples, the terminator I 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;

[0036] 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 used. 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;

[0037] 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;

[0038] In some examples, the separation device in step (12) is a single-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);

[0039] For example, in the resulting heavy-component trimeric polyisocyanate composition after separation treatment, the residual monomer content is less than or equal to 0.1 wt% based on the mass of the composition.

[0040] In the second embodiment, a method for a TMP polyisocyanate composition includes the following steps:

[0041] (21) Obtain a reaction solution through a prepolymerization reaction: React a polyol compound with a diisocyanate in a first reaction kettle;

[0042] (22) Feed the material obtained in step (21) into a second reaction kettle for reaction;

[0043] (23) Remove the unreacted diisocyanate monomer from the material obtained in step (22) through a separation device;

[0044] (24) Dilute the resulting heavy-component polyisocyanate composition in step (23) with a solvent to obtain a polyisocyanate composition solution.

[0045] In step (21) of the present invention, the polyol compound can be added to the reaction kettle alone for mixing and reaction with the diisocyanate, or can be pre-mixed and then reacted with the diisocyanate. The pre-mixing method includes a pipe mixer or pre-mixing in a pre-mixing tank in advance. In the present invention, a pipe mixer is preferably used for mixing.

[0046] In step (21) of the present invention, the material can enter the reaction kettle in step (21) at room temperature for reaction, or enter the reaction kettle in step (21) after preheating for reaction. In the present invention, it is preferred that the material is preheated to 60 - 100 °C for reaction.

[0047] In step (21) of the present invention, the reaction temperature of the material in the first reaction kettle is 100 - 170 °C, preferably 100 - 150 °C, more preferably 110 - 140 °C.

[0048] In method step (21) of the present invention, the average residence time of the material in the first reaction kettle is 3 - 30 minutes, preferably 5 - 15 minutes.

[0049] In step (21) of the present invention, stabilizers and additives can be added to reduce the change of product color number. These stabilizers and additives are conventional additives in the field of polyisocyanates. They include but are not limited to: antioxidants, sterically hindered phenols (such as antioxidant BHT, antioxidant 1010, antioxidant 1076, antioxidant, antioxidant 1135, etc.), phosphite esters (such as tris(nonylphenyl) phosphite, tris(2,4 - di - tert - butylphenyl) phosphite, etc.), ultraviolet absorbers (such as benzotriazoles, salicylate esters, benzophenones, etc.), and hindered amine light stabilizers (such as 2,2,6,6 - tetramethylpiperidine), etc.

[0050] In step (21) of the present invention, the polyol compound contains TMP and DEG. As another solution, it can also include one or more of other di - , tri - , and tetra - valent alcohols with a molecular weight of 62 to 200, such as but not limited to ethylene glycol, 1,2 - propylene glycol, methyl propylene glycol, 1,3 - propylene glycol, 1,2 - butylene glycol, 1,3 - butylene glycol, 1,4 - butylene glycol, 1,5 - pentanediol, neopentyl glycol, 1,6 - hexanediol, 2 - ethylhexanediol, trimethylolethane, glycerol, and pentaerythritol, etc.

[0051] As a preferred solution, in the polyol compound of step (21) of the present invention, the mass ratio of TMP to DEG is 1:1 - 5:1, preferably 2:1 - 4:1.

[0052] As another preferred solution, in the polyol compound of step (21) of the present invention, the mass ratio of TMP to DEG is 1:1 - 5:1, preferably 2:1 - 4:1. In addition to TMP and DEG, the total mass ratio of other polyols to the mass of TMP is 1:5 - 1:50.

[0053] In step (22) of the present invention, the reaction temperature of the material in the second reaction kettle is 60 - 100 °C, preferably 60 - 80 °C, more preferably 65 - 75 °C.

[0054] In step (22) of the present invention, the average residence time of the material in the second reaction kettle is 2 - 20 hours, preferably 5 - 10 hours.

[0055] In step (23) of the present invention, the obtained material is passed through a separation device to remove unreacted diisocyanate monomers. In some examples, the separation treatment means for removing unreacted isocyanate monomers is a conventional operation in the art and is not particularly limited herein; the separation device used can be, for example, an extraction device, a rotary evaporator, a short-path evaporator or a thin-film evaporator, or a combination thereof, to remove the remaining unreacted isocyanate monomers until the isocyanate monomer content in the product is low, for example, ≤0.5 wt% based on the mass of the composition, preferably less than or equal to 0.4 wt%.

[0056] In step (24) of the present invention, the heavy-component polyisocyanate composition obtained in reaction step (23) is diluted with a solvent to obtain a polyisocyanate composition solution. The organic solvent used is one or more of toluene, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate and propylene glycol methyl ether acetate, preferably ethyl acetate.

[0057] In step (24) of the method of the present invention, the solid content of the polyisocyanate composition solution is 30 - 80 wt%, preferably 50 - 80 wt%.

[0058] In step (24) of the method of the present invention, the dilution solvent is preheated to 30 - 80 °C, preferably 50 - 70 °C.

[0059] In the third embodiment, a method for preparing an isocyanate prepolymer includes the following steps:

[0060] (31) Under nitrogen protection, an isocyanate is added to a reaction kettle, and a polyether polyol is continuously added to the reaction kettle at the reaction temperature. After the dropping is completed, a catalyst is added and the reaction continues;

[0061] (32) After reaching a suitable conversion rate, 40% - 85% of an alicyclic diisocyanate based on the total mass of the isocyanate prepolymer is added, stirred evenly, and cooled to room temperature to obtain the product;

[0062] In the method described above, 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.

[0063] In the described method, the polyether polyol is a polypropylene oxide ether polyol, a polyethylene oxide ether polyol, a polypropylene oxide-ethylene oxide ether polyol, or any mixture thereof; preferably a polypropylene oxide ether polyol or a polypropylene oxide-ethylene oxide ether polyol, and more preferably a 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 tetrol, 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.

[0064] In the described method, the alicyclic isocyanate can be selected from isophorone diisocyanate, dicyclohexylmethane diisocyanate, or methylcyclohexyl diisocyanate, or any mixture thereof, preferably isophorone diisocyanate or dicyclohexylmethane diisocyanate.

[0065] In the present invention, 40%-85% of the alicyclic diisocyanate, preferably 50-70% of dicyclohexylmethane diisocyanate, is added based on the total mass of the isocyanate prepolymer.

[0066] 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%.

[0067] In the method of the present invention, 0.01-0.06% of a catalyst is added based on the total mass of the reaction system. The catalyst is selected from one or more of dibutyltin dilaurate, stannous octoate, iron acetylacetonate, zinc octoate, lead octoate, potassium oleate; and is further preferably dibutyltin dilaurate or stannous octoate.

[0068] The present invention also relates to a storage method for a polyisocyanate composition. The polyisocyanate composition is stored in a container, and the gas phase space of the packaged product is replaced with nitrogen while oxygen is supplemented. Among them, the volume fraction of oxygen in the gas phase space of the packaged product is controlled at 0.5-25%.

[0069] Another object of the present invention is also to provide the application of the storage-stable polyisocyanate composition or the storage-stable polyisocyanate composition 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.

[0070] 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.

[0071] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0072] In the process of preparing the polyisocyanate composition of the present invention, by controlling the oxygen content in the gas phase space of the packaged product to 0.5-25%, a polyisocyanate composition product with excellent storage stability is obtained. Detailed implementation manners

[0073] In order to better understand the technical solution of the present invention, the following further elaborates the content of the present invention in combination with embodiments, but the content of the present invention is not limited to the following embodiments only.

[0074] Testing methods:

[0075] (1) Determination of the content of free isocyanate monomer:

[0076] Use 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 SDplus 100A5μm (8.0*300mm) in series, Shimadzu; mobile phase: tetrahydrofuran; flow rate: 1.0 mL / min; analysis time: 40 min, chromatographic column temperature: 35°C) for the quantification of isocyanate raw materials, and determine the areas of polymers and monomers in the system to be tested by the area normalization method. The isocyanate monomer content (%) = S (isocyanate monomer peak area) / S (sum of peak areas of each component) * 100%.

[0077] (2) NCO% content test, referring to the standard GB / T 12009.4;

[0078] (3) Determination method of product viscosity: The dynamic mechanical viscosity is measured using a BrookField DV-IPrime viscometer with an S21 rotor at 25°C;

[0079] (4) Determination method of product color number: Based on the method of GB / T 3143-1982, measure the color number in a 50mm disposable rectangular cuvette using a LICO 400 from HACH Lange.

[0080] (5) Air oxygen test conditions

[0081] 1. Instrument configuration:

[0082] The instrument is a gas chromatography system composed of a ten-way valve (injecting and backflushing functions), a six-way valve (isolation valve), three chromatographic columns (2 P-N columns and one MS-13X column), and a TCD detector.

[0083] 2. Method setting (reference):

[0084]

[0085] 3. Quantitative method

[0086] 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.

[0087] In the following examples and comparative examples, the chemical raw material information is as follows. Unless otherwise specified, other raw materials are all common commercially available raw materials:

[0088] 1,6-Hexamethylene diisocyanate , Wanhua Chemical ;

[0089] Toluene diisocyanate Wanhua Chemical ;

[0090] Dicyclohexylmethane diisocyanate Wanhua Chemical ;

[0091] Polyether polyol (Wanol R2307), Wanhua Chemical;

[0092] 2-Ethyl-1,3-hexanediol, trimethylolpropane TMP, diethylene glycol DEG, purity ≥ 99%, Sigma-Aldrich;

[0093] Tetraethylammonium hydroxide solution (concentration 25 wt%, methanol solution), Sigma-Aldrich;

[0094] Bis(2-ethylhexyl) phosphate: purity > 98.5%, Aladdin reagent.

[0095] Dibutyltin dilaurate: purity > 98.5%, Aladdin reagent.

[0096] 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 the protection of dry nitrogen. Unless otherwise stated, all percentages in the text are mass percentages.

[0097] Product preparation example 1

[0098] (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) and carry out a polymerization reaction. Track and measure the NCO% of the reaction solution. When the NCO content rate in the reaction solution reaches 40 wt%, add 3,200 g of bis(2-ethylhexyl) phosphate to terminate the reaction, and obtain an HDI trimer polyisocyanate reaction solution.

[0099] (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 unreacted isocyanate monomers, and obtain a heavy component, that is, an HDI trimer polyisocyanate composition containing an isocyanurate structure.

[0100] Test the prepared polyisocyanate composition. Its chromaticity is 15 Hazen, the viscosity is 2,800 mPa·s (25 °C), and the content of residual HDI monomer is 0.08 wt%.

[0101] Product Preparation Example 2

[0102] (1) The continuous reaction system consists of 2 series-connected jacketed reaction kettles. The volume of the first reaction kettle is 100 L, the volume of the second reaction kettle is 5,000 L. The temperature of the first reaction kettle is set at 130 ± 2 °C, and the temperature of the second reaction kettle is set at 70 ± 2 °C. Inject 50 L and 3,000 L of TDI-80 into the 2 series-connected reaction kettles respectively in advance. Each stage of the reaction kettle controls the temperature of the reaction kettle by means of jacket heating and internal coil heat transfer, and reacts in an isothermal manner. Then add TDI (antioxidant BHT is added in advance, equivalent to 300 ppm of the mass of TDI), TMP and DEG into the first reaction kettle continuously. The added weight ratio of TDI:TMP:DEG is 20:2:1. The materials are preheated to 80 ± 1 °C, the feed flow rate is controlled, the average residence time of the materials in the first reaction kettle is 10 minutes, and then it overflows to the second reaction kettle. The average residence time of the materials in the second reaction kettle is 10 hours.

[0103] (2) The polyisocyanate reaction liquid is separated and treated by a two-stage thin film evaporator, wherein the separation temperature of the first-stage thin film evaporator is 170±2.5°C and the separation absolute pressure is 100Pa, and the separation temperature of the second-stage thin film evaporator is 170±2.5°C and the separation absolute pressure is 20Pa, to remove the unreacted TDI monomer in the reaction system, and then add it to ethyl acetate preheated to 70°C, mix thoroughly, and then cool to 30°C to obtain the product, thereby obtaining a heavy component, i.e., a polyisocyanate composition product containing TDI adduct.

[0104] The prepared polyisocyanate composition was tested and found to have a chromaticity of 23 Hazen, a viscosity of 1680 mPa·s (25° C.), and a residual TDI monomer content of 0.18 wt %.

[0105] Product Preparation Example 3

[0106] Under nitrogen protection, 3200 kg of hexamethylene diisocyanate was added to the reactor, heated and stirred in an 80°C oil bath, and when the system temperature reached 80°C, 3500 kg of polyether polyol Wanol R2307 was added dropwise to the reactor. After the dropwise addition was completed, 0.02% of dibutyltin dilaurate, based on the total mass of the reaction system, was added, and the reaction system was stirred and reacted at 80°C for 2 hours, and then 10000 kg of dicyclohexylmethane diisocyanate was added and stirred evenly. The final prepolymer product had an NCO content of 25.0%, a viscosity of 360 cp / 25°C, a dicyclohexylmethane diisocyanate monomer content of 60%, and a product color number of 16 Hazen.

[0107] [Application Example]

[0108] The products prepared in the above product preparation example were filled into 200L stainless steel barrels by a filling machine. The filling volume of each barrel was 190L. Nitrogen was used to replace the gas phase space of the packaged products. At the same time, a corresponding amount of oxygen was added according to the following example. The experimental results are shown in Table 1:

[0109] Table 1. Experimental results

[0110]

[0111] Those skilled in the art will appreciate that, based on the teachings of this specification, some modifications or adjustments may be made to the present invention, and 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 storage, wherein, The volume fraction content of oxygen in the gas phase of the residual space of the packaged product is 0.5-25%.

2. The preparation method of the polyisocyanate composition according to claim 1, characterized in that, Including: S1: The reaction of isocyanate monomer with polyol, or the self-polymerization reaction of isocyanate; S2: After reaching the conversion rate, add a terminator or not add a terminator to end the reaction to obtain a polyisocyanate reaction solution; S3: Optionally, the polyisocyanate reaction solution obtained in S2 is separated and treated through an evaporator; S4: Dilute the separated heavy components obtained in S3 with a solvent or not dilute with a solvent, and package to obtain a product.

3. The preparation method 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, benzene dimethylene diisocyanate, dicyclohexylmethane diisocyanate, norbornane dimethylene diisocyanate, cyclohexyl diisocyanate, lysine diisocyanate, tetramethylbenzene dimethylene diisocyanate, 2,4,4-trimethylhexane diisocyanate, toluene diisocyanate, methylcyclohexyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenylene polyisocyanate; And / or, S1 is carried out in the presence or absence of a catalyst.

4. The preparation method according to any one of claims 2-3, 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 isocyanurate structure, urethane structure, urethane structure, biuret structure, iminooxadiazinedione structure, uretdione structure, carbodiimide structure, and uretonimine structure.

5. The preparation method according to any one of claims 2-4, characterized in that, The polyisocyanate reaction solution is separated and treated through 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. Use of a polyisocyanate composition with stable storage as described in claim 1, characterized in that, After being blocked by a blocking agent, it is used in the fields including the preparation of polyurethane coatings and polyurethane adhesives.

7. A storage method for a polyisocyanate composition, wherein, The volume fraction of oxygen in the gas phase space of the packaged product is controlled at 0.5-25%.

8. The storage method according to claim 7, wherein, The preparation method of the polyisocyanate composition includes: S1: The reaction of isocyanate monomer with polyol, or the self-polymerization reaction of isocyanate; S2: After reaching the conversion rate, add a terminator or not add a terminator to end the reaction to obtain a polyisocyanate reaction solution; S3: Optionally, the polyisocyanate reaction solution obtained in S2 is separated and treated through an evaporator; S4: Dilute the finally separated heavy components obtained in S3 with a solvent or not dilute with a solvent, and package to obtain a product.

Images