CN109651278B - Preparation method of polyisocyanate - Google Patents
Preparation method of polyisocyanate Download PDFInfo
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- CN109651278B CN109651278B CN201811344978.4A CN201811344978A CN109651278B CN 109651278 B CN109651278 B CN 109651278B CN 201811344978 A CN201811344978 A CN 201811344978A CN 109651278 B CN109651278 B CN 109651278B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/30—Only oxygen atoms
- C07D251/34—Cyanuric or isocyanuric esters
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D273/00—Heterocyclic compounds containing rings having nitrogen and oxygen atoms as the only ring hetero atoms, not provided for by groups C07D261/00 - C07D271/00
- C07D273/02—Heterocyclic compounds containing rings having nitrogen and oxygen atoms as the only ring hetero atoms, not provided for by groups C07D261/00 - C07D271/00 having two nitrogen atoms and only one oxygen atom
- C07D273/04—Six-membered rings
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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
- C08G18/02—Polymeric products of isocyanates or isothiocyanates of isocyanates or isothiocyanates only
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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
- C08G18/02—Polymeric products of isocyanates or isothiocyanates of isocyanates or isothiocyanates only
- C08G18/022—Polymeric products of isocyanates or isothiocyanates of isocyanates or isothiocyanates only the polymeric products containing isocyanurate groups
Abstract
The invention discloses a method for preparing polyisocyanate, which comprises the steps of carrying out self-polymerization reaction on isocyanate under the catalysis of a fluorine-containing catalyst, and adding a terminator to terminate the reaction after the reaction is finished to obtain a reaction solution; removing unreacted isocyanate monomer to obtain polyisocyanate; the fluorine content in the polyisocyanate is controlled to not more than 80 ppm. The method of the invention controls the fluorine content in the product, avoids the turbidity phenomenon of the product during low-temperature storage, and also effectively reduces the toxicity, equipment hazard and downstream hazard of the fluorine in the system.
Description
Technical Field
The invention relates to a preparation method of a polyisocyanate curing agent product.
Background
The polyisocyanate prepared by polymerizing the aliphatic diisocyanate monomer is widely applied to the polyurethane coating or adhesive industry, and the harm of the volatile isocyanate monomer to human bodies can be effectively reduced by self-polymerization of the isocyanate.
The isocyanate monomer can be polymerized to obtain uretdione (structural formula 1), trimer (structural formula 2) and iminooxadiazinedione (structural formula 3), and the three structures have characteristics and influence the performance of the product. The viscosity of the uretdione is minimum, the functionality is small, the functionality of the tripolymer is large, the viscosity is high, the viscosity of the iminooxadiazinedione is smaller than that of the tripolymer, the functionality is higher than that of the uretdione, the viscosity is low, the construction is facilitated, and the functionality is high, so that the curing is facilitated.
The existing methods for preparing polyisocyanates have been widely reported, and the catalysts used in the methods are mainly alkyl phosphine, fluoro acid compound, triazole salt compound, polyfluorinated salt, fluorinated salt and the like, for example, US5914383A and CN1243124A describe the preparation of polyisocyanate containing iminooxadiazinedione by using polyfluorinated salt as catalyst, wherein the iminooxadiazinedione content is high and the product turbidity is high (more than 1 NTU).
Patent US4937339 uses fluoride salts in combination with quaternary ammonium salts and polyethylene oxide to prepare polyisocyanates, but the content of iminooxadiazinedione is low, the content of trimer is too high, the viscosity of the product is large, and it is mentioned that agglomerated particles are easily generated during the reaction.
US7595396 uses a fluoroacid ion catalyst to prepare iminooxadiazinedione-containing polyisocyanates, the resulting product has a high content of iminooxadiazinedione, but insoluble materials are likely to appear in the product.
US6107484 proposes a method of adding a protonating solvent to a fluoride salt to prepare a polyisocyanate having a high content of iminooxadiazinedione, but fluorine still needs to be introduced into the catalyst, and there are many references in the examples that insoluble matter is easily generated during the reaction.
In the prior art, the fluorine content of the polyisocyanate product obtained by catalytic preparation by using a fluorine-containing catalyst is generally 150-200 ppm. The above publications relate to the use of fluorine in the preparation of polyisocyanates, which products are prone to precipitation during storage at low temperatures, resulting in insoluble matter, e.g., -20 ℃, and are therefore not suitable for downstream consumer applications in cold regions.
Disclosure of Invention
In view of the above, the present invention provides a method for preparing polyisocyanate, which can effectively reduce the fluorine content in the product, greatly improve the low-temperature stability of the product, avoid the turbidity phenomenon of the product during low-temperature storage, and also effectively reduce the toxicity, equipment hazard and downstream hazard of fluorine in the system.
In order to realize the purpose of the invention, the invention adopts the following technical scheme:
the invention provides a method for preparing polyisocyanate, which comprises the steps of carrying out self-polymerization reaction on isocyanate under the catalysis of a fluorine-containing catalyst, and adding a terminator to terminate the reaction after the reaction is finished to obtain a reaction solution; removing unreacted isocyanate monomer to obtain polyisocyanate;
the fluorine content in the polyisocyanate is controlled to not more than 80 ppm.
In the preparation process of the invention, preferably, the reaction solution after the reaction is stopped is cooled to-30 to 30 ℃, and is adsorbed or filtered by fluorine-containing materials, such as-10 ℃, 0 ℃ and 10 ℃. The isocyanate raw material mainly comprises carbon, hydrogen, oxygen and nitrogen elements, the fluorine-containing compound (fluorine phase compound) and the compound (hydrocarbon phase compound) without fluorine are poorer in compatibility under the condition that the temperature is-30 ℃, and the fluorine-containing material is more beneficial to removing fluorine substances in the filtering or adsorbing process. Fluorine-containing materials such as polytetrafluoroethylene filter bags, polytetrafluoroethylene filter cartridges or polytetrafluoroethylene packings; the fluorine-containing material is adopted for adsorption or filtration treatment, so that the solubility of fluorine in the reaction liquid is further reduced, and fluorine substances in the reaction liquid are effectively filtered out.
In the preparation process of the present invention, products with different properties can be obtained by the self-polymerization reaction with different conversion rates, and in some preferred embodiments, when the conversion rate of the self-polymerization reaction is 20% to 50%, the fluorine-containing terminator is added to control the molar content of the iminooxadiazinedione group and the molar content of the isocyanurate group in the obtained polyisocyanate to be 0.5 to 1.5, more preferably 1.0 to 1.4, such as 1.1, 1.2. Specifically, the content of isocyanate can be quantitatively calculated by a gel chromatography technology in the preparation process, the calculation is used as a judgment standard of the reaction conversion rate, when the conversion rate of the obtained self-polymerization reaction is 20-50%, the fluorine-containing terminator is added, so that the molar content of the iminooxadiazine dione groups and the molar content of the isocyanurate groups in the obtained polyisocyanate can be controlled within the range, the obtained product has low viscosity, the construction is convenient, and the method has unique advantages in the downstream application process.
In the preparation method of the present invention, the adopted terminator is a fluorine-containing terminator. In some embodiments, the fluorine-containing terminator has the following structure of formula (I):
CnF2n+1(CH2)xO(CH2CH2O)mh formula (I)
Wherein n is an integer of 1 to 10, preferably 2 to 6;
m is an integer from 1 to 15, preferably from 3 to 8;
x is 0, 1, 2, 3.
In the structure of the above formula (I), n may be more preferably 3,4,5, and m may be more preferably 4,5, 7.
The terminator of the above structure can be obtained by addition polymerization by a known production method by the following reaction:
the preparation method of the invention obviously reduces the fluorine content in the product through the combined action of the fluorine-containing terminator and the fluorine-containing catalyst. The fluorine-containing catalyst and the fluorine-containing terminator belong to surfactant substances in isocyanate raw materials, and the inventor of the application finds that the fluorine-containing catalyst and the fluorine-containing terminator are mainly enriched on the surfaces in the reaction process, are very easy to contact and react, and the mutual reaction of the terminator and the catalyst leads to the inactivation of the catalyst so as to generate the fluorine substances with larger molecules.
The method can generate larger fluorine-containing molecules based on the fluorine-containing terminator and the fluorine-containing catalyst, and increases incompatibility by using low temperature; meanwhile, when the reaction liquid after reaction is absorbed and filtered, the principle of similar compatibility is utilized, fluorine-containing materials such as solid polytetrafluoroethylene materials can absorb and remove fluorine substances, the fluorine removal efficiency is improved, and the fluorine content in the product is further reduced.
In the preparation method of the present invention, the fluorine-containing catalyst preferably has a structure represented by the following formula (ii):
wherein R is1、R2、R3、R4Same or different, each independently selected from linear or branched C1～C15Alkyl radicals, e.g. methyl, propyl, butyl, C7～C15The aralkyl group of (2) wherein the hydrogen atom on the benzene ring is substituted by an arbitrary group, preferably an alkyl group or a cycloalkyl group, such as tolyl, ethylphenyl and butylphenyl, or C6～C12The aryl group of (a) wherein the hydrogen atom on the benzene ring is substituted by any group, preferably by an alkyl or cycloalkyl group, such as phenyl, diphenyl;
z is selected from N or P;
y is selected from fluorine or polyfluoro ions (F (HF)n)-Wherein n is an integer of 1-10, preferably 3-8, such as 4,5, 6.
In the preparation method of the present invention, the amount of the fluorine-containing catalyst is preferably 10 to 1000ppm, more preferably 15 to 500ppm, and even more preferably 20 to 100ppm, such as 50ppm and 80ppm, based on the mass of the isocyanate; the molar ratio of the terminating agent to the fluorine-containing catalyst is preferably 1:1 to 2:1, more preferably 1:1 to 1.5:1, for example, 1:1 to 1.2:1, 1:1 to 1.4: 1.
In the preparation process of the present invention, the catalyst may be used undiluted or dissolved in a solvent. All solvents have the characteristic that the catalyst is soluble and does not decompose and does not react at all with isocyanates or, when reacted with isocyanates, forms only the non-destructive downstream products which are very common in polyurethane chemistry, including urethanes, allophanates, etc. Preferably, the catalyst is added to the reaction system in the form of solution, and the solvent used for the catalyst is one or more of methanol, ethanol, isobutanol, hexanol, tert-butanol and 1, 4-butanediol; the concentration of the catalyst solution is 10 to 90 wt%, preferably 30 to 80 wt%, for example, 40 wt%, 60 wt%.
In the preparation method of the present invention, the fluorine content in the fluorine-containing material is preferably 50% to 80%, preferably 60% to 70%, for example, 63% and 67%, where the fluorine content refers to the mass content of fluorine; preferably, the fluorine-containing material is a solid fluorine-containing material, preferably a polytetrafluoroethylene material, and further preferably has the following structure (iii):
[CF2-CF2]nformula (III)
Wherein n is 100 to 100000, more preferably 200 to 5000, and even more preferably 500 to 3000, such as 600, 1000, 2000.
Further preferably, the fluorine-containing material is a polytetrafluoroethylene filter bag, a polytetrafluoroethylene filter element or polytetrafluoroethylene filler;
more preferably, the aperture of the polytetrafluoroethylene filter bag and the aperture of the polytetrafluoroethylene filter element are between 5-100um, preferably 10-50um, such as 20um and 40um, and the particle size of the polytetrafluoroethylene filler is 0.5-1.5 mm, preferably 0.7-1.3 mm, such as 1mm and 1.2 mm.
In the production method of the present invention, the isocyanate raw material is preferably C4～C20Aliphatic diisocyanate of (2), C4～C20And C6～C20One or more of (a) aromatic diisocyanate (b);
further preferably, the isocyanate raw material is one or more of hexamethylene diisocyanate, pentamethylene diisocyanate, 2-methylpentane-1, 5-diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 1, 4-bis (isocyanatomethyl) cyclohexane, norbornane dimethylene isocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4, 4-trimethylhexamethylene diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.
The manner in which the isocyanate starting material is prepared is not critical to the preparation process of the present invention, including the monomers which may be produced with or without phosgene or by any other method.
In the preparation method, the self-polymerization reaction is carried out under the protection of inert gas, and the temperature of the self-polymerization reaction is 10-100 ℃, more preferably 40-80 ℃, for example, 50 ℃ and 60 ℃; the inert gas is preferably nitrogen and/or argon.
In the preparation method, unreacted isocyanate monomers are removed by adopting a film evaporation, molecular distillation or extraction mode; specifically, the temperature of the film evaporation is 130-160 ℃, the temperature of the molecular distillation is 140-150 ℃, and the solvent used for extraction is selected from hydrocarbon solvents, such as n-hexane and cyclohexane.
In addition, some additives can be added into the product according to downstream requirements in the preparation method process of the invention to improve the performance of the product, for example, hindered phenol (2, 6-di-tert-butyl toluene, 4-methyl-2, 6-di-tert-butyl toluene) is added as an antioxidant to improve the color number of the product, and hindered amine light stabilizer (HA L S) is added as a light stabilizer to effectively inhibit photooxidation degradation.
The fluorine content in the polyisocyanate obtained by the preparation method is controlled to be not higher than 80 ppm; further preferably, the fluorine content is not more than 50ppm, more preferably not more than 30 ppm.
The fluorine content in the present invention specifically means a mass content of fluorine in a polyisocyanate product, and the fluorine includes an ionic fluorine form, a hydrated fluorine ion form, or a covalent fluorine form.
Compared with the prior art, the invention has the following advantages:
according to the invention, the fluorine-containing catalyst is introduced to catalyze the self-polymerization reaction in the preparation process, so that the low-temperature stability of the turbidity of the final product is enhanced, and the turbidity phenomenon of the product during low-temperature storage is avoided.
The polyisocyanate prepared by the preparation method has the fluorine content of below 80ppm, so that the system toxicity, equipment hazard and downstream hazard of fluorine in a system are effectively reduced. Obviously controls the harm of fluorine and reduces the problem of fluorine accumulation in the monomer recycling process.
Detailed Description
The technical solution and the effects of the present invention are further described by the following specific examples. It should be understood that the following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention. Simple modifications of the invention applying the inventive concept are within the scope of the invention as claimed.
The following test methods were used in the examples of the invention:
method for testing monomer content in isocyanate raw material: adopting the national standard GB/T18446-;
method for determining the content (mol%) of iminooxadiazinedione, isocyanurate, uretdione: calculated from integrated proton decoupling 13C NMR spectra (obtained on a Bruker DPX-400 instrument) and based on the sum of the isocyanurates, iminooxadiazinediones, uretdiones present, respectively; each structural element has the following chemical shifts (in ppm): iminooxadiazinedione: 147.8, 144.3 and 135.3; isocyanurate (b): 148.4; uretdione: 157.1;
detection of fluorine element: testing by oxygen bomb combustion-ion chromatography;
the method comprises the steps of quantifying raw material diisocyanate monomer by using a Gel chromatography technology as a monitoring means for judging the reaction conversion rate (calculated based on the mass of the raw material diiso-acetic acid monomer), wherein L C-20AD/RID-10A is adopted as a series connection of chromatographic columns, wherein the chromatographic columns are MZ-Gel SDplus 10E3A 5um (8.0 × 300mm), MZ-Gel SDplus 500A 5um (8.0 × 300mm), MZ-Gel SDplus 100A 5um (8.0 × 300mm), Shimadzu, a mobile phase of tetrahydrofuran, a flow rate of 1.0m L/min, an analysis time of 40min and a chromatographic column temperature of 35 ℃;
and (3) viscosity detection: the test was carried out at a temperature of 25 ℃ using a VT550 viscometer manufactured by Haak.
Information on raw materials and instrumentation in the following examples:
hexamethylene diisocyanate: wanhua, wannate HDI, 99%;
pentamethylene diisocyanate: mitsui, STABIO PDI, 98%;
n-hexanol: sigma-Aldrich, 98%;
n-hexane: sigma-Aldrich, 98%;
tetramethylammonium bifluoride: sigma-Aldrich, 95%;
tetrabutylammonium fluoride: sigma-Aldrich, 95%;
a polytetrafluoroethylene filter element, kobaite, L PF 0045D;
the polytetrafluoroethylene filter bag is made of Kebaite, L PF 0045E;
polytetrafluoroethylene packing: PVDF T1;
tetrabutylphosphonium difluoride: prepared based on the preparation method mentioned in example 1 in patent CN 99109785.8;
tetrabutylammonium difluoride TC L, 95%.
The terminating agents in the following examples were obtained by the following method:
C2F5CH2O(CH2CH2O)3h: 1mol of perfluoropropanol (C) in a reaction kettle at the temperature of 80 DEG C2F5CH2OH) and 0.001mol of potassium hydroxide are mixed, the mixture is heated for 0.5h under the vacuum pressure of 1000Pa, then the vacuum is removed, 3.5mol of ethylene oxide is added, the temperature is raised to 90 ℃, the pressure is kept at 0.15MPa, the reaction is continued for 2h, then the residual ethylene oxide is removed, and the product is obtained after the filtration by a PE filter element;
C6F13CH2CH2O(CH2CH2O)4h: 1mol of perfluorooctanol (C) at 85 ℃ in a reaction kettle6F13CH2CH2OH) and 0.001mol of potassium hydroxide are mixed, the mixture is heated for 1 hour under the vacuum pressure of 500Pa, then the vacuum is removed, 4.5mol of ethylene oxide is added, the temperature is raised to 95 ℃, the pressure is kept at 0.2MPa, the reaction is continued for 2.5 hours, then the residual ethylene oxide is removed, and the mixture is subjected to PEFiltering by a filter element to obtain a product;
C3F7CH2O(CH2CH2O)10h: 1mol of perfluorobutanol (C) at 85 ℃ in a reaction kettle3F7CH2OH) and 0.001mol of potassium hydroxide are mixed, the mixture is heated for 1h under the vacuum pressure of 800Pa, then the vacuum is removed, 11mol of ethylene oxide is added, the temperature is raised to 90 ℃, the pressure is kept at 0.2MPa, the reaction is continued for 3h, then the residual ethylene oxide is removed, and the product is obtained after the filtration by a PE filter element.
Example 1
a) Placing 800g of HDI (hexamethylene diisocyanate) in a round-bottom flask provided with a reflux condenser, a stirrer, a thermometer and a nitrogen inlet, heating to 70 ℃, adding 0.5g of 70 wt% of n-hexanol solution of tetrabutyl phosphonium difluoride, and carrying out self-polymerization reaction under continuous stirring, wherein the reaction temperature is controlled to be 70-75 ℃; when the conversion of the monomer in the self-polymerization reaction reached 30%, C was immediately added in an equimolar amount to tetrabutylphosphonium difluoride2F5CH2O(CH2CH2O)3H, continuing stirring for 15min to terminate the reaction;
b) cooling the reaction liquid to-20 ℃, and filtering the reaction liquid by a two-stage polytetrafluoroethylene filter element, wherein the aperture of the polytetrafluoroethylene filter element is 50 um;
c) and evaporating and removing unreacted raw materials contained in the reaction liquid by using a thin film evaporator under the conditions of the temperature of 150 ℃ and the absolute pressure of 100Pa to ensure that the monomer content is lower than 0.5 wt%, thus obtaining the polyisocyanate product.
Through detection, the content of fluorine element in the polyisocyanate product obtained in the example 1 is 30 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups is 1, and the viscosity of the product at 25 ℃ is 680 cP.
Comparative examples 1 to 1
The process conditions of comparative example 1-1 were the same as example 1 except that: the terminator used was benzoyl chloride.
Through detection, the content of fluorine element in the polyisocyanate product obtained in the comparative example 1-1 is 100 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups is 1, and the viscosity of the product at 25 ℃ is 690 cP.
Comparative examples 1 to 2
Comparative examples 1-2 the process conditions were the same as in example 1, except that: after the reaction is finished, the unreacted isocyanate is directly removed from the reaction liquid by evaporation at 150 ℃ under the absolute pressure of 100Pa by using a film evaporator.
Through detection, the content of fluorine element in the polyisocyanate product obtained in the comparative example 1-2 is 200 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups is 1, and the viscosity of the product at 25 ℃ is 670 cP.
Comparative examples 1 to 3
a) Placing 800g of HDI in a round-bottom flask provided with a reflux condenser tube, a stirrer, a thermometer and a nitrogen inlet, heating to 70 ℃, adding 0.5g of 70 wt% of n-hexanol solution of tetrabutyl phosphonium difluoride, and carrying out self-polymerization reaction under continuous stirring, wherein the reaction temperature is controlled to be 70-75 ℃; when the conversion rate of the monomer in the self-polymerization reaction reaches 30 percent, benzoyl chloride with the same molar weight as tetrabutyl phosphine difluoride is immediately added, and the reaction is stopped after continuously stirring for 15 min;
b) and (3) evaporating and removing unreacted raw materials contained in the reaction liquid by using a thin film evaporator under the conditions of the temperature of 150 ℃ and the absolute pressure of 100Pa to ensure that the monomer content is lower than 0.5 wt%, thus obtaining the polyisocyanate product.
Through detection, the content of fluorine element in the polyisocyanate products obtained in the comparative examples 1-3 is 250 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups was 0.9, and the product viscosity at 25 ℃ was 710 cP.
Example 2
a) 1000g HDI (hexamethylene diisocyanate) was placed in a round-bottomed flask equipped with a reflux condenser, a stirrer, a thermometer and a nitrogen inlet, heated to 60 ℃ and added with 0.8g of a 50 wt% n-hexanol solution of tetramethylammonium difluoride, and self-polymerization was carried out with continuous stirring while controlling reverse reactionThe temperature is between 60 and 65 ℃; when the conversion rate of the monomer in the self-polymerization reaction reaches 40 percent, adding C with the same molar amount as the tetramethylammonium bifluoride immediately6F13CH2CH2O(CH2CH2O)4H, continuing stirring for 15min to terminate the reaction;
b) cooling the reaction liquid to 10 ℃, and adsorbing the reaction liquid by two-stage polytetrafluoroethylene filler, wherein the particle size of the polytetrafluoroethylene filler is 1.0 mm;
c) extracting the reaction liquid after adsorption by using cyclohexane at 40 ℃, wherein the mass ratio of normal hexane to the reaction liquid is 2:1, continuously extracting for three times, removing unreacted raw materials contained in the reaction liquid, and enabling the monomer content to be lower than 0.5 wt%, thereby obtaining a polyisocyanate product.
Through detection, the detection result of the content of fluorine element in the polyisocyanate product obtained in example 2 is as follows:
50 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups was 1.2, and the product viscosity was 620cP at 25 ℃.
Comparative example 2
Comparative example 2 compared with example 2, in step b), the reaction solution after termination is directly adsorbed by two-stage polytetrafluoroethylene fillers at 60 ℃, and the particle size of the polytetrafluoroethylene fillers is 1.0 mm;
through detection, the detection result of the content of the fluorine element in the polyisocyanate product obtained in the comparative example 2 is as follows: 120 ppm; the ratio of the molar content of iminooxadiazinedione groups to the molar content of isocyanurate groups in the product was 1.15, and the viscosity at 25 ℃ was 650 cP.
Example 3
a) Putting 1000g of pentamethylene diisocyanate into a round-bottom flask provided with a reflux condenser tube, a stirrer, a thermometer and a nitrogen inlet, heating to 60 ℃, adding 1g of a 60 wt% n-hexanol solution of tetrabutylammonium fluoride, and carrying out self-polymerization reaction under continuous stirring, wherein the reaction temperature is controlled to be 60-65 ℃; when the conversion of the monomer in the self-polymerization reaction reaches 40%, C is added immediately in an equimolar amount to tetrabutylammonium fluoride3F7CH2O(CH2CH2O)10H, continuing stirring for 15min to terminate the reaction;
b) cooling the reaction liquid to-30 ℃, and filtering the reaction liquid through two stages of polytetrafluoroethylene filter bags, wherein the aperture of each polytetrafluoroethylene filter bag is 70 mu m;
c) and evaporating and removing unreacted raw materials contained in the reaction liquid by using a thin film evaporator under the conditions of the temperature of 150 ℃ and the absolute pressure of 100Pa to ensure that the monomer content is lower than 0.5 wt%, thus obtaining the polyisocyanate product.
Through detection, the detection result of the content of fluorine element in the polyisocyanate product obtained in example 3 is as follows: 60 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups was 1.1, and the product viscosity was 710cP at 25 ℃.
Example 4
Example 4 compared to example 3, the difference is: 0.5g of a 60 wt% n-hexanol solution of tetrabutylammonium difluoride is selected as a catalyst;
through detection, the detection result of the content of fluorine element in the polyisocyanate product obtained in example 4 is as follows: 50 ppm; the ratio of the molar content of iminooxadiazinedione groups in the product to the molar content of isocyanurate groups was 1.08, and the product viscosity at 25 ℃ was 720 cP.
The above product was placed in an aluminum bottle and stored at-18 ℃ in a refrigerator, and the phenomenon was observed, with the results shown in table 1:
TABLE 1 product appearance change upon low temperature storage
| Initial | After 1 month | After 2 months | After 3 months | |
| Example 1 | Clarification | Clarification | Clarification | Clarification |
| Comparative examples 1 to 1 | Clarification | Clarification | Clarification | Turbidity |
| Comparative examples 1 to 2 | Clarification | Clarification | Turbidity | Turbidity |
| Comparative examples 1 to 3 | Clarification | Turbidity | Turbidity | Turbidity |
| Example 2 | Clarification | Clarification | Clarification | Clarification |
| Comparative example 2 | Clarification | Clarification | Clarification | Turbidity |
| Example 3 | Clarification | Clarification | Clarification | Clarification |
| Example 4 | Clarification | Clarification | Clarification | Clarification |
As can be seen from the data in the above Table 1, the polyisocyanate product obtained by the preparation method of the present invention can still maintain a clear state at a low temperature after 3 months, and has good apparent properties; the polyisocyanate products obtained in comparative examples 1-1 and 2 can still keep a clear state at low temperature after 2 months, but have a turbid phenomenon after 3 months; the polyisocyanate products obtained in comparative examples 1-2 showed cloudiness at low temperature after 2 months and had poor appearance properties; the polyisocyanate products obtained in comparative examples 1 to 3 showed cloudiness at low temperatures after 1 month and had poor appearance properties.
Claims (20)
1. A method for preparing polyisocyanate is characterized in that under the protection of inert gas, isocyanate is subjected to self-polymerization reaction under the catalysis of a fluorine-containing catalyst, a fluorine-containing terminator is added after the reaction is finished to terminate the reaction to obtain a reaction liquid, the reaction liquid after the termination reaction is cooled to-30 ℃, and fluorine-containing materials are used for adsorption or filtration treatment; removing unreacted isocyanate monomer to obtain polyisocyanate;
the fluorine content in the polyisocyanate is controlled to be not higher than 80 ppm;
the fluorine-containing terminator has the following structure:
CnF2n+1(CH2)xO(CH2CH2O)mh formula (I)
Wherein n is an integer of 1 to 10;
m is an integer of 1 to 15;
x is 0, 1, 2, 3;
the fluorine-containing catalyst has a structure represented by the following formula (II):
wherein R is1、R2、R3、R4Same or different, each independently selected from linear or branched C1～C15Alkyl, optionally substituted C7～C15Aralkyl or optionally substituted C6～C12Aryl of (a);
z is selected from N or P;
y is selected from fluorine or a polyfluoro ion having the structure (F (HF))n)-Wherein n is an integer of 1-10.
2. The process of claim 1, wherein the polyisocyanate obtained has a ratio of the molar content of iminooxadiazinedione groups to the molar content of isocyanurate groups of 0.5 to 1.5.
3. The method according to claim 1, wherein in the formula (i), n is an integer of 2 to 6; m is an integer of 3 to 8.
4. The method according to claim 1, wherein the fluorine-containing catalyst is used in an amount of 10 to 1000ppm based on the mass of the isocyanate; the molar ratio of the usage amount of the terminating agent to the usage amount of the fluorine-containing catalyst is 1: 1-2: 1.
5. The method according to claim 4, wherein the fluorine-containing catalyst is added to the reaction system in the form of a solution, and the solvent in the fluorine-containing catalyst solution is selected from one or more of methanol, ethanol, isobutanol, hexanol, tert-butanol, and 1, 4-butanediol; the concentration of the fluorine-containing catalyst solution is 10-90 wt%.
6. The method according to claim 5, wherein the concentration of the fluorine-containing catalyst solution is 30 to 80 wt%.
7. The method of claim 1, wherein the fluorine-containing material is a solid fluorine-containing material.
8. The method of claim 7, wherein the fluorine-containing material is a polytetrafluoroethylene material.
9. The method of claim 8, wherein the fluorine-containing material is of the following formula (iii):
[CF2-CF2]nformula (III)
Wherein n is 100 to 100000.
10. The method according to claim 9, wherein n in the formula (III) is 200 to 5000.
11. The method according to claim 10, wherein n in the formula (III) is 500 to 3000.
12. The method according to claim 1, wherein the fluorine-containing material contains fluorine in an amount of 50 to 80% by mass.
13. The method of claim 8, wherein the fluorine-containing material is a teflon filter bag, a teflon filter element, or a teflon packing.
14. The method as claimed in claim 13, wherein the polytetrafluoroethylene filter bag and the polytetrafluoroethylene filter element have a pore size of 5-100um, and the particle size of the polytetrafluoroethylene filler is 0.5-1.5 mm.
15. The method of claim 14, wherein the polytetrafluoroethylene filter bags and the polytetrafluoroethylene filter elements have a pore size of 10-50 um.
16. The method of any one of claims 1-15, wherein the isocyanate is C4～C20Aliphatic diisocyanate of (2), C4～C20And C6～C20One or more of (a) aromatic diisocyanate (b).
17. The process of claim 16, wherein the isocyanate is one or more of hexamethylene diisocyanate, pentamethylene diisocyanate, 2-methylpentane-1, 5-diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, 1, 4-bis (isocyanatomethyl) cyclohexane, norbornane dimethylene isocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4, 4-trimethylhexamethylene diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.
18. The method according to any one of claims 1 to 15, wherein the self-polymerization is carried out at a temperature of 10 to 100 ℃.
19. The method of claim 1, wherein the inert gas is nitrogen and/or argon.
20. The method of claim 18, wherein the unreacted isocyanate monomer is removed by membrane evaporation, molecular distillation or extraction.
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| CN110540633B (en) * | 2019-09-12 | 2021-06-29 | 万华化学集团股份有限公司 | Polyisocyanate composition and preparation method thereof |
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| DE10123417A1 (en) * | 2001-05-14 | 2002-11-21 | Bayer Ag | Production of polyisocyanates containing uretedione groups comprises oligomerizing isophorone diisocyanate in the presence of a catalyst consisting of a triazolate salt |
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