CN117343278A - Storage-stable polyisocyanate composition and preparation method thereof - Google Patents

Storage-stable polyisocyanate composition and preparation method thereof Download PDF

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Publication number
CN117343278A
CN117343278A CN202210733871.9A CN202210733871A CN117343278A CN 117343278 A CN117343278 A CN 117343278A CN 202210733871 A CN202210733871 A CN 202210733871A CN 117343278 A CN117343278 A CN 117343278A
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polyisocyanate
diisocyanate
evaporator
polyisocyanate composition
structures
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石滨
尚永华
张现锋
张明
李晶
薛勇勇
王京旭
姚飞洋
孙立冬
黎源
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Wanhua Chemical Group Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/77—Polyisocyanates or polyisothiocyanates having heteroatoms in addition to the isocyanate or isothiocyanate nitrogen and oxygen or sulfur
    • C08G18/78—Nitrogen
    • C08G18/79—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates
    • C08G18/791—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing isocyanurate groups
    • C08G18/792—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing isocyanurate groups formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
    • C09J175/04—Polyurethanes

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Polyurethanes Or Polyureas (AREA)

Abstract

The present invention provides a storage stable polyisocyanate composition and a process for preparing the same. The composition is prepared by carrying out polymerization reaction on diisocyanate monomers in the presence of a catalyst system, stopping the reaction after the conversion rate is reached, obtaining polyisocyanate reaction liquid, and separating to obtain the polyisocyanate composition, wherein the proportion of isocyanate containing carbodiimide structure in the composition accounts for 0.1-2mol% of the polyisocyanate product, and the color number of the product is less than or equal to 30Hazen. The product is especially suitable for being used in high-temperature and high-humidity areas.

Description

Storage-stable polyisocyanate composition and preparation method thereof
Technical Field
The invention belongs to the technical field of preparation of isocyanate derivatives, and particularly relates to a polyisocyanate composition with stable storage and a preparation method thereof.
Background
It is known that polyurethane resin coatings have excellent abrasion resistance, chemical resistance, stain resistance, and particularly polyurethane resin coatings prepared using polyisocyanates derived from aliphatic (cyclo) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and the like, have excellent weather resistance. Therefore, these polyisocyanates are often used as a coating for coating buildings, automobiles, airplanes, ships, cross-sea bridges, and for repairing thereof in the form of a polyurethane coating which is heat-cured at ordinary temperature.
At present, processes for preparing polyisocyanates by polymerization of aromatic, aliphatic or cycloaliphatic diisocyanate monomers in the presence of catalysts are known, the advantages and disadvantages of various catalyst systems being discussed in detail in the prior art, for example J.Prakt.chem.336 (1994) 185-200, C.201410002995.5, C.N.9513103.6, C.N.200310120368.3, C.N.200310120121.1, C.N.20091012628.1, C.N.201280059016.9.
However, the polyisocyanate products prepared by the prior art have the main disadvantage of poor moisture resistance during downstream use, and are very susceptible to deterioration during sub-packaging by customers, which seriously affects use in high temperature and high humidity areas. In view of this, it is of particular importance to find an improvement in the stability of the polyisocyanates during storage.
Disclosure of Invention
The object of the present invention is to provide a storage-stable polyisocyanate composition which solves the problems of the prior art in terms of storage stability, and surprisingly shows that the moisture resistance of the product is better and the color number of the product is not affected when the proportion of carbodiimide structures in the polyisocyanate composition is 0.1 to 2mol% based on the polyisocyanate product.
In order to achieve the above purpose, the technical scheme provided by the invention is as follows:
a polyisocyanate composition with stable storage is prepared through polymerizing diisocyanate monomer in the presence of catalyst system, stopping reaction to obtain polyisocyanate reaction liquid, and separating to obtain polyisocyanate composition, wherein the proportion of isocyanate containing carbodiimide structure in said composition is 0.1-2mol% of polyisocyanate product, and the color number of product is less than or equal to 30Hazen.
In accordance with some examples of the polyisocyanate compositions provided herein, one or more of isocyanurate structures, urethane structures, allophanate structures, biuret structures, iminooxadiazinedione structures, uretdione structures, carbodiimide structures, and uretonimine structures are included in the polyisocyanate composition.
In some examples, the polyisocyanate composition is a trimeric polyisocyanate, a biuret polyisocyanate, or a uretdione polyisocyanate.
For example, one or more of isocyanurate structures, urethane structures, allophanate structures, iminooxadiazinedione structures, uretdione structures, carbodiimide structures, and uretonimine structures may be included in the trimeric polyisocyanate.
For example, one or more of a biuret structure, a carbodiimide structure, a uretdione structure, and a uretonimine structure may be included in the biuret polyisocyanate.
For example, one or more of a uretdione structure, an isocyanurate structure, a urethane structure, an allophanate structure, an iminooxadiazinedione structure, a carbodiimide structure, and a uretonimine structure may be included in the uretdione polyisocyanate.
According to some examples of the polyisocyanate compositions provided herein, the isocyanate monomer is selected from one or more of aromatic organic isocyanate, aliphatic organic isocyanate and alicyclic organic isocyanate, preferably one or more of Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), cyclohexyldimethylene diisocyanate (HMDI), xylylene Diisocyanate (XDI), dicyclohexylmethane diisocyanate (HXDI), norbornane dimethylene diisocyanate (NBDI), cyclohexyldiisocyanate (CHDI), lysine Diisocyanate (LDI), tetramethylxylylene diisocyanate (TMXDI), 2, 4-trimethylhexamethylene diisocyanate (TMHDI), toluene Diisocyanate (TDI), methylcyclohexyl diisocyanate (HTDI), naphthalene Diisocyanate (NDI), terephthal-benzene diisocyanate (PPDI), diphenylmethane diisocyanate (MDI) and polymethylene polyphenyl Polyisocyanate (PM).
It is another object of the present invention to provide a process for the preparation of the polyisocyanate composition.
The method comprises the steps of carrying out polymerization reaction on diisocyanate monomers in the presence of a catalyst system, stopping the reaction after the conversion rate is reached to obtain polyisocyanate reaction liquid, and separating to obtain the polyisocyanate composition, wherein the separation treatment is carried out in such a way that the polyisocyanate reaction liquid is separated by a scraper evaporator; preferably, the wiped film evaporator is in the form of one or more of a thin film evaporator and/or a short path evaporator, preferably the wiped film evaporator has a two or three stage.
In one embodiment, the method of preparation is:
(1) The diisocyanate monomer is subjected to polymerization reaction in the presence of a catalyst system, and the reaction is terminated after the conversion rate is reached to obtain polyisocyanate reaction liquid; and then separating to obtain the polyisocyanate composition.
(2) Wherein the polyisocyanate reaction liquid is separated by an evaporator in the form of one or a combination of more of a thin film evaporator or a short path evaporator; the number of stages of the separation treatment evaporator is two or three;
(3) The thermal residence time of the separated reaction liquid between the first stage and the second stage is 5-60 minutes. The reaction liquid is separated between the first stage and the second stage, and the content of residual diisocyanate monomer is 0.5-5wt%.
The term "conversion" as used herein is understood to mean a conversion which is predetermined according to the desired product. Different types of polyisocyanate products, which have different conversions to be achieved, can be converted and represented by controlling the NCO% value of the reaction system; this is well known to those skilled in the art and will not be described in detail herein.
The applicant has surprisingly found that by subjecting the reaction solution to a high temperature treatment between the primary and secondary stage, the moisture resistance of the product is better when the carbodiimide structure is controlled to be in the range of 0.1 to 2% of the polyisocyanate product in the isocyanate composition.
It has been found that if the reaction solution is subjected to a high-temperature heat treatment before separation, the molecular weight distribution of the reaction solution is not significantly changed due to the presence of a certain amount of unreacted monomers in the reaction solution, so that the molecular weight distribution of the final product is less changed due to the heat balance, but a part of undesirable uretonimine is generated, which affects the downstream application performance. If the final separated product is subjected to high-temperature heat treatment, the product is partially decomposed or polymerized in the heating process due to the small unreacted monomer content, so that the molecular weight distribution of the product is greatly changed, the monomer content is increased, and the downstream application performance is further affected.
In the method, the scraper evaporator is a scraped film evaporator, which comprises a rotor with a scraper and an evaporator cylinder part with a heating jacket, the materials to be separated are uniformly dispersed on the inner wall of the evaporator cylinder through a disperser arranged at the upper part of the evaporator, the materials naturally flow down through gravity, the rotor with the scraper rotates at a constant speed to scrape the materials into a thin liquid film, free monomers with low boiling point escape from the liquid film, and the non-volatile heavy components and a small amount of residual free monomers enter a next separation device. The evaporator cylinder part with the heating jacket is heated by the heated heat conduction oil or water vapor to provide heat for the materials to be separated.
The process conditions are very critical to control in the heat treatment temperature of heavy components in the liquid discharged from the first-stage evaporator, a buffer tank is arranged between the first-stage evaporator and the second-stage evaporator in the separated reaction liquid, and the residence time of materials in the buffer tank and the content of residual isocyanate monomers in the buffer tank are adjusted by adjusting the temperature of the buffer tank according to different physical properties of polyisocyanate.
It is found through exploration that if the heat treatment time is too long, the color number and viscosity of the product change greatly; if the heat treatment time is too short, the effect of improving the stability is not achieved as well. Therefore, the heat residence time of the heavy components in the first-stage evaporator liquid in the buffer tank is 5-60 minutes, and the ideal treatment effect is ensured by selecting the proper heat residence time based on the different polyisocyanate products.
Through exploration, if the temperature of the heat treatment is too high, the color number and the viscosity of the product are greatly changed; if the temperature of the heat treatment is too low, the effect of improving the stability is not achieved. Therefore, the heat retention temperature in the heavy component buffer tank of the first-stage evaporator is 120-200 ℃, and the ideal treatment effect is ensured by selecting the proper heat treatment temperature based on different polyisocyanate products.
In the present invention, the method of preparing the isocyanate monomer as a raw material is not critical to the practice of the preparation method of the present invention, and includes isocyanate monomers which can be produced with or without phosgene or any other method, for example, aromatic, aliphatic and/or alicyclic organic isocyanates, which are organic diisocyanates or organic polyisocyanates containing 4 to 20 carbon atoms in addition to NCO groups in the carbon skeleton.
In some examples, the separation treatment means for removing the unreacted isocyanate monomer is a conventional operation in the art, and is not particularly limited; the separation device used may be, for example, an extraction device, a rotary evaporator, a short path evaporator or a thin film evaporator, and combinations thereof, and the residual unreacted isocyanate monomer is removed from the resulting reaction liquid until the isocyanate monomer content in the product is low, for example, 0.5% by weight or less based on the mass of the composition.
In the present invention, the preparation process of the different types of polyisocyanate products may be different.
For example, the polyisocyanate composition may be a trimeric polyisocyanate.
In a first embodiment, a method for preparing a storage stable polyisocyanate comprises the steps of:
(11) Under inert atmosphere, adding isocyanate monomer into a reaction container, heating, adding (for example, dropwise adding) a catalyst I after the system is heated to a reaction temperature, carrying out polymerization reaction, and tracking and measuring NCO of a reaction solution; when the NCO% value is reduced to a proper value (for example, 35-45%), adding a terminator I to terminate the reaction to obtain a trimeric polyisocyanate reaction solution;
(12) Separating the trimeric polyisocyanate mixture by a separating device (for example, a two-stage thin film evaporator), and performing heat treatment on the heavy component in the primary separation lower liquid of the obtained trimeric polyisocyanate, wherein the temperature of the heat treatment is 180-185 ℃, the heat treatment time is 5-20min, and the monomer content in the heavy component in the primary separation lower liquid is 0.5-1%; then separating and removing unreacted isocyanate monomer through a secondary evaporator to prepare trimeric polyisocyanate;
for example, the trimeric polyisocyanate reaction liquid includes a polyisocyanate containing one or more of an isocyanurate structure, a urethane structure, an allophanate structure, an iminooxadiazinedione structure, a uretdione structure, a carbodiimide structure and a uretonimine structure, and preferably includes a polyisocyanate containing an isocyanurate structure, a urethane structure, an allophanate structure, an iminooxadiazinedione structure, a uretdione structure, a carbodiimide structure and a uretonimine structure. In the trimer reaction liquid, different structures can be characterized by nuclear magnetism, the nuclear magnetism of different structures has different peak positions, and isocyanurate groups: near 148.5ppm, uretdione group: near 157.3ppm allophanate groups: around 154ppm, carbamate: around 156.3ppm iminooxadiazinedione: near 145ppm biuret groups: around 155.9ppm, uretonimine: near 149.8ppm, carbodiimide: near 133.2 ppm.
In some examples, the catalyst I of step (11) is a quaternary ammonium base and/or quaternary ammonium salt type catalyst, preferably selected from choline hydroxide, trimethylhydroxyethyl ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, 1-adamantylammonium hydroxide, hexamethyldiammonium hydroxide, organic weak acid salts of tetraalkylammonium (e.g., tetramethylammonium, tetraethylammonium, etc.), organic weak acid salts of tetramethylammonium octoate, trimethylhydroxypropyl ammonium (e.g., formic acid, acetic acid, capric acid, etc.), organic weak acid salts of trimethylhydroxyethyl ammonium (e.g., formic acid, acetic acid, capric acid, etc.).
The organic weak acid salt of tetraalkylammonium described herein can be tetramethylammonium formate, tetramethylammonium acetate, tetramethylammonium decanoate, tetraethylammonium formate, tetraethylammonium acetate, tetraethylammonium decanoate; the organic weak acid salt of the trimethyl hydroxypropyl ammonium can be trimethyl hydroxypropyl ammonium formate, trimethyl hydroxypropyl ammonium acetate and trimethyl hydroxypropyl ammonium caprate; the organic weak acid salt of trimethyl hydroxyethyl ammonium can be trimethyl hydroxyethyl ammonium formate, trimethyl hydroxyethyl ammonium acetate and trimethyl hydroxyethyl ammonium decanoate.
In some examples, the catalyst I is added in an amount of 0.001wt% to 0.1wt% (e.g., 0.0025wt%, 0.005wt%, 0.01wt%, 0.04wt%, 0.06wt%, 0.08 wt%) based on the weight of the isocyanate monomer.
The catalyst I may be used as pure substance or optionally dissolved in an alcohol in any concentration. As a diluent for the catalyst, the alcohol may be, but is not limited to, a monohydric alcohol and/or a dihydric alcohol; 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, more preferably in the form of a linear, branched or cyclic alcohol or phenol. The diol may be, but is not limited to, 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.
In some examples, the terminator I of 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 di (2-ethylhexyl) phosphate.
It will be appreciated by those skilled in the art that the type of polymerization catalyst used in the reaction system will vary, resulting in varying amounts of the terminating agent. In the reaction system of the present invention, the terminator I is added in an amount such that the polymerization catalyst I in the system is deactivated.
In some examples, the reaction temperature of step (11) is 30-100deg.C (e.g., 35 ℃, 50 ℃, 60 ℃, 70 ℃, 90 ℃), preferably 40-80 ℃.
In some examples, the separation device of step (12) is a two-stage wiped film evaporator; the film scraping system of the film scraping evaporator can be a roller type or a scraper type, and the evaporator can be a thin film evaporator or a short-range evaporator. The process conditions of the separation treatment comprise: the separation temperature of the first-stage wiped film evaporator is 140-180 ℃ (140 ℃ and 160 ℃ and 180 ℃ for example), and the absolute separation pressure is 5-200Pa (5 Pa, 10Pa, 50Pa, 100Pa and 200Pa for example); the second-stage wiped film evaporator has a separation temperature of 140-180deg.C (e.g., 140deg.C, 160deg.C, 180deg.C) and a separation absolute pressure of 5-100Pa (e.g., 5Pa, 10Pa, 50Pa, 100 Pa).
For example, the residual monomer content in the trimeric polyisocyanate composition obtained after the separation treatment is 0.15% by weight or less based on the mass of the composition.
Furthermore, in the preparation process of the present invention, stabilizers and additives, which are conventional additives in the polyisocyanate field, may be added at any desired timing. Including but not limited to: antioxidants, hindered phenols (e.g., 2, 6-di-t-butyl-4-methylphenol, octadecyl 3, 5-di-t-butyl-4-hydroxyphenyl propionate, etc.), phosphites (e.g., tris (nonylphenyl) phosphite, tris (2, 4-di-t-butylphenyl) phosphite, etc.), ultraviolet absorbers (e.g., benzotriazoles, salicylates, benzophenones, etc.), and hindered amine light stabilizers (e.g., 2, 6-tetramethylpiperidine), etc.
The invention also relates to polyurethane coatings and polyurethane adhesives prepared from the polyisocyanate compositions described above or the polyisocyanates prepared by the preparation methods described above.
It is a further object of the present invention to provide the use of a polyisocyanate composition.
The application of the polyisocyanate composition, namely the polyisocyanate composition or the polyisocyanate composition prepared by the preparation method, is applicable to various auxiliary agent systems and various isocyanate raw material systems, and is preferably applied to the fields of oily polyurethane paint, aqueous polyurethane materials and yellowing-resistant polyurethane materials.
The polyisocyanate composition prepared by the polyisocyanate composition or the preparation method can be used for preparing polyurethane coating, polyurethane adhesive and other related products after being blocked by a blocking agent.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
in the process of preparing the polyisocyanate composition, the heat treatment is carried out on the primary separation liquid heavy component, and meanwhile, the treatment temperature and the residence time of the primary separation liquid heavy component are controlled, so that when the carbodiimide structure proportion in the polyisocyanate composition accounts for 0.1-2% of that of a polyisocyanate product, the moisture resistance performance of the product is good, and the color number of the product is not affected.
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 testing method comprises the following steps:
(1) Determination of the content of free isocyanate monomer:
the determination of the area of the polymer and monomer in the system to be tested was carried out by means of Gel chromatography (LC-20 AD/RID-10A, column chromatography MZ-Gel SD plus10E3A,5 μm (8.0 x 300 mm), MZ-Gel SDplus 500A 5 μm (8.0 x 300 mm), MZ-Gel SDplus 100A5 μm (8.0 x 300 mm) in series, shimadzu, mobile phase: tetrahydrofuran, flow rate: 1.0mL/min, analysis time: 40min, column chromatography temperature: 35 ℃) and determination of the area of the polymer and monomer in the system to be tested by means of area normalization, isocyanate monomer content (%) =S (sum of isocyanate monomer peak areas)/S (sum of peak areas of the components): 100%.
(2) NCO% content test, reference standard GB/T12009.4;
(3) The method for measuring the viscosity of the product comprises the following steps: dynamic mechanical viscosity was measured using a Brookfield DV-I Prime viscometer using an S21 spindle at 25 ℃;
(4) The method for measuring the color number of the product comprises the following steps: color number was measured in a 50mm disposable rectangular cuvette using LICO 400 from the company HACH Lange, based on the method of GB/T3143-1982.
(5) Carbodiimide content in polyisocyanate composition: isocyanurate group molar ratio can be quantified by the composition 13 C-NMR test. Specific test conditions are as follows:
13 C-NMR apparatus: AVANCE600 (Bruker), BBO probe (Bruker), sample concentration: 30wt%, resonance frequency: 150MHz, displacement reference: 77.0ppm (CDCl 3), pulse procedure: zgig30, spectral width: 240ppm, spectral center: 100ppm;
isocyanurate group: 148.5ppm vicinity integrated value/3, uretdione group: 157.3ppm vicinity integration value/2, allophanate group: 154ppm vicinity integrated value/1, urethane: 156.3ppm vicinity integration value/1, iminooxadiazinedione: integral value/1 around 145ppm biuret group: integrated value around 155.9 ppm/2, uretonimine: integrated value/1 around 149.8ppm, carbodiimide: integrated value around 133.2 ppm/2;
carbodiimide mole percentage= (133.2 ppm vicinity integral value/2)/((148.5 ppm vicinity integral value/3) + (157.3 ppm vicinity integral value/2) + (154 ppm vicinity integral value/1) + (156.3 ppm vicinity integral value/1) + (145 ppm vicinity integral value/1) + (155.9 ppm vicinity integral value/2) + (149.8 ppm vicinity integral value/1) + (133.2 ppm vicinity integral value/2)).
Chemical raw material information:
1, 6-hexamethylene diisocyanate,HDI, vanning chemistry;
2-ethyl-1, 3-hexanediol with purity greater than or equal to 99%, sigma aldrich;
tetraethylammonium hydroxide solution (25 wt% strength in methanol solution), sigma aldrich;
trimethylhydroxyethyl ammonium hydroxide solution (25 wt% strength, methanol solution);
benzyl trimethyl ammonium hydroxide solution (25 wt% strength, methanol solution);
di (2-ethylhexyl) phosphate (diisooctyl phosphate): purity > 98.5%, aara Ding Shiji;
dibutyl phosphate: purity > 98.5%, and ala Ding Shiji.
The following examples and comparative examples were conducted under the protection of dry nitrogen gas until the catalyst was added and throughout the reaction, without specific explanation. All percentages herein are by mass unless otherwise indicated.
The scraper evaporator used in the embodiment is a scraped film evaporator and comprises a rotor with a scraper and an evaporator cylinder part with a heating jacket, materials to be separated are uniformly dispersed on the inner wall of the evaporator cylinder through a disperser arranged on the upper part of the evaporator, the materials naturally flow down through gravity, the rotor with the scraper rotates at a constant speed to scrape the materials into a thin liquid film, free monomers with low boiling point escape from the liquid film, and non-volatile heavy components and a small amount of residual free monomers enter a next separation device. The evaporator cylinder part with the heating jacket is heated by the heated heat conduction oil to provide heat for the materials to be separated.
Example 1
(1) 1000g of Hexamethylene Diisocyanate (HDI) is added into a reaction device and heated to 70 ℃, 2g of 2-ethyl-1, 3-hexanediol solution (concentration: 25wt percent, methanol solution) of tetraethylammonium hydroxide solution (concentration: 20wt percent) is added for polymerization reaction, and NCO in the reaction solution is tracked and measured; when the NCO content of the reaction solution reached 39.2% by weight, 0.22g of di (2-ethylhexyl) phosphate was added to terminate the reaction, to obtain an HDI trimeric polyisocyanate reaction solution.
(2) The obtained HDI trimer polyisocyanate reaction liquid is separated by two-stage serial thin film evaporators, wherein the separation temperature of the first-stage thin film evaporator is 155+/-2.5 ℃, the absolute separation pressure is about 100Pa, the separation temperature of the second-stage thin film evaporator is 156+/-2.5 ℃, the absolute separation pressure is about 20Pa, and unreacted isocyanate monomers are removed, so that the HDI trimer polyisocyanate composition is obtained.
(3) Wherein the heavy components separated by the primary thin film evaporator in the step (2) enter a primary lower liquid heavy component buffer tank, the heat residence time in the buffer tank is 5min, the temperature is 195-200 ℃ (the fluctuation range is 5 ℃), and the primary lower liquid heavy components after heat treatment enter a secondary thin film evaporator for further separation.
Examples 2 and 3 and comparative examples 1 and 2 were conducted as in example 1 except that the heat retention time, temperature and time of the first-stage lower liquid heavy component in the first-stage lower liquid heavy component buffer tank were different.
The corresponding isocyanate compositions and process parameters are shown in the following table.
Table 1 parameters and results of examples and comparative examples
Remarks: the method for testing the number of times of opening the barrel comprises the steps of adopting 20kg of packaged products, opening the barrel mouth for 10 minutes at the temperature of 30 ℃ and the humidity of 90%, then observing whether the products are skinned or not after sealing for 1 week, and judging that the products are deteriorated if other analysis indexes are in the COA range and the clouding phenomenon or the product indexes exceed the COA indexes, and ending the experiment.
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.

Claims (7)

1. The polyisocyanate composition with stable storage is prepared through polymerization of diisocyanate monomer in the presence of catalyst, stopping reaction after reaching conversion rate to obtain polyisocyanate reaction liquid, and separating to obtain the polyisocyanate composition, and features that the proportion of isocyanate containing carbodiimide structure in the composition is 0.1-2mol% of the polyisocyanate product and the color number of the product is less than or equal to 30Hazen.
2. The polyisocyanate composition of claim 1 wherein the polyisocyanate composition comprises one or more of isocyanurate structures, urethane structures, allophanate structures, biuret structures, iminooxadiazinedione structures, uretdione structures, carbodiimide structures, and uretonimine structures.
3. The polyisocyanate composition according to claim 1 or 2, wherein the isocyanate monomer 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, cyclohexylhexamethylene diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, norbornane dimethylene diisocyanate, cyclohexyldiisocyanate, lysine diisocyanate, tetramethylxylylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, toluene diisocyanate, methylcyclohexyl diisocyanate, naphthalene diisocyanate, terephthalene diisocyanate and polymethylene polyphenyl polyisocyanate.
4. A process for the preparation of a polyisocyanate composition according to any one of claims 1 to 3, which comprises polymerizing a diisocyanate monomer in the presence of a catalyst system, terminating the reaction after the conversion has been reached to obtain a polyisocyanate reaction solution, and separating the polyisocyanate reaction solution to obtain a polyisocyanate composition, wherein the separation is carried out by separating the polyisocyanate reaction solution by a wiped film evaporator;
preferably, the wiped film evaporator is in the form of one or more of a thin film evaporator and/or a short path evaporator, preferably the wiped film evaporator has a two or three stage.
5. The method according to claim 4, wherein when a multistage evaporator is used, the separated reaction liquid is provided with a buffer tank for heavy components between the first-stage evaporator and the second-stage evaporator, and the heavy components separated by the first-stage evaporator enter a buffer tank for heavy components in the first-stage lower liquid;
preferably, the thermal residence time of the first-stage evaporator downliquid heavies in the buffer tank is from 5 to 60 minutes.
6. The method according to claim 4 or 5, wherein the heat retention temperature in the first-stage evaporator lower liquid heavy component buffer tank is 120 to 200 ℃.
7. Use of a polyisocyanate composition according to any one of claims 1 to 3 or a polyisocyanate composition prepared by the preparation process according to any one of claims 4 to 6, for various adjuvant systems as well as for various isocyanate raw material systems, preferably in the field of oily polyurethane paints, aqueous polyurethane materials, yellowing-resistant polyurethane materials.
CN202210733871.9A 2022-06-27 2022-06-27 Storage-stable polyisocyanate composition and preparation method thereof Pending CN117343278A (en)

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