CN103922969B - A kind of method preparing the hexamethylene diisocyanate of colour stable - Google Patents
A kind of method preparing the hexamethylene diisocyanate of colour stable Download PDFInfo
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Abstract
The present invention relates to a kind of method preparing the hexamethylene diisocyanate of colour stable.The method is with low boiling component, namely 1, the 6-hexanediamine of the content≤50mg/kg of tetrahydroazepine, 1-amino-2-cyano group-1-cyclopentenes and ACN is raw material, carries out gas phase phosgenation reaction, the hexamethylene diisocyanate obtained has good colour stability.
Description
Technical field
The present invention relates to a kind of preparation method of hexamethylene diisocyanate, relate to a kind of preparation method of hexamethylene diisocyanate of colour stable more specifically.
Background technology
Corresponding isocyanic ester can be prepared by the gas phase phosgenation reaction of aliphatic series or aromatic amine.The isocyanic ester obtained by this method, its color is unstable usually, and produces adverse influence to the color of isocyanic ester derived product.Causing the reason of isocyanic ester variable color to have a lot, is not that in raw material aliphatic series or aromatic amine, all impurity directly can produce inevitable or unwelcome variable color in isocyanic ester or its derived product.
Patent US4065362 discloses a kind of method of organic isocyanate of purifying, and improves the stability in storage of isocyanic ester color by removing unknown impuritie in isocyanic ester.Patent US3715381 by adding 1-30mg/kg(in isocyanate in isocyanic ester) 2,4-bis-(tertiary butyl) p-cresol (BHT) improve the colour stability of isocyanic ester.Patent US2957903 discloses a kind of method improving isocyanic ester colour stability, improves the colour stability of isocyanic ester in storage process by the tricresyl phosphite aromatic ester adding 50-500mg/kg in isocyanic ester.Mode by adding position phenol resistance anti-oxidant or the composite organophosphite oxidation inhibitor of secondary aryl amine oxidation inhibitor in patent US7297746 improves the colour stability of isocyanic ester.Along with the raising of people's environmental consciousness, the use of phenols and aromatic species additive can be subject to the restriction of downstream application requirement gradually.Meanwhile, the Application Areas of part isocyanic ester also has larger restriction requirement to the kind of additive.Strengthen the colour stability of isocyanic ester, reduce or do not add these additives having great significance.
Summary of the invention
The object of the present invention is to provide a kind of method preparing the hexamethylene diisocyanate of colour stable, the hexamethylene diisocyanate prepared by the method, there is good colour stability.
For reaching above object, the invention provides following technical scheme:
The invention provides one and prepare 1, the method of hexamethylene-diisocyanate, to have or under inertialess medium existent condition, 1,6-hexanediamine and phosgene carry out phosgenation reaction in the reaction region, be fed to amount of components having low boiling points≤50mg/kg in 1, the 6-hexanediamine in phosgenation reaction district, preferably≤40mg/kg, more preferably≤30mg/kg, particularly preferably≤10mg/kg, with 1,6-hexanediamine raw material weight meter.
Low boiling component in 1,6-hexanediamine of the present invention refer to boiling point lower than and close to the impurity composition of 1,6-hexanediamine boiling point, specifically comprise tetrahydroazepine, 1-amino-2-cyano group-1-cyclopentenes and ACN.
The content of the low boiling component in 1,6-hexanediamine of the present invention can be controlled by multiple known method, usually adopts the mode of distillation to control the content of the low boiling component in 1,6-hexanediamine.Such as there is detailed describing at patent US7468119, US7973192, US6248926 etc. to adopting the mode of distillation 1,6-hexanediamine of purifying.
Phosgenation reaction of the present invention carries out in the gas phase, and the gasification of 1,6-hexanediamine is carried out in advance, and 1,6-hexanediamine of the gas phase obtained dripless before entering reaction zone exists.
In order to realize object of the present invention, from the mixing of raw material, reacting to forming reactions product and carrying out a reaction zone.After reaction product leaves reaction zone, 1,6-hexanediamine and phosgene are in reaction zone complete reaction.The generation of side reaction can be reduced like this, reduce the formation of sulfonylurea, thus improve the total recovery of isocyanic ester, reduce forming sedimentary chance simultaneously, extend the reaction zone exercisable time.
The present invention can adopt interval, mode that is semicontinuous or continuous print operation realizes, and preferably adopts the mode of operate continuously.The HCl gas of 0-10wt% can be contained in phosgene of the present invention.
Inert media of the present invention is selected from the one or two or more in nitrogen, rare gas (such as argon or helium), aromatics (such as chlorobenzene, dichloro benzene,toluene,xylene), carbon monoxide and carbonic acid gas etc., is preferably selected from the one or two or more in nitrogen, chlorobenzene and dichlorobenzene.
The consumption of inert media of the present invention calculates with the inert media gas volume after gasification, and the volume ratio of inert media gas and 1,6-hexanediamine gas is 0.001-5:1, preferred 0.01-3:1, more preferably 0.1-1:1.
1,6-hexanediamine photoreactive gas can be fed in reaction zone together with inert media.Inert media mixes with 1,6-hexanediamine and/or phosgene usually before the reaction, preferably mixes with 1,6-hexanediamine before the gasification of 1,6-hexanediamine, thus the gasification of auxiliary 1,6-hexanediamine, shorten vaporization time, reduce the energy consumption of 1,6-hexanediamine gasification.
The hexamethylene diisocyanate that 1,6-hexanediamine photoreactive gas is formed in reaction zone in gaseous state, namely gets rid of the situation having drop to be formed in reaction zone at reaction conditions.
The mol ratio of phosgene of the present invention and 1,6-hexanediamine is 2-20:1, preferred 4-10:1, more preferably 6-8:1.
The temperature of reaction zone of the present invention is 300-500 DEG C, is preferably 350-450 DEG C.
The absolute pressure of reaction zone of the present invention is 0.05-0.3MPa, preferred 0.07-0.2MPa, more preferably 0.09-0.18MPa.
Reaction zone upstream abutting raw material transfer lime of the present invention, downstream adjoins process area, as the cooling of gas-phase reaction product or spray washing region.Enter the pressure height 0.002-0.2MPa of the pressure ratio reaction zone in 1,6-hexanediamine photoreactive gas feed line of reaction zone, preferred high 0.003-0.1MPa; The low 0.001-0.05MPa of pressure of the pressure ratio reaction zone of the process area adjoined with downstream, reaction zone, preferred low 0.003-0.02MPa.
The flow velocity that 1,6-hexanediamine photoreactive gas incoming flow stock enters reaction zone is being 5-100m/s, preferred 10-80m/s.
In the reaction region, the average contact time of 1,6-hexanediamine photoreactive gas in reaction zone is 0.01-15s, preferred 0.04-10s, more preferably 0.08-5s.
The reaction mixture in reaction zone to be made to reach turbulence state for the reaction compartment size of reaction zone and the selection of flow velocity, namely the Reynolds number value of stream of reaction mixture is greater than 3000, be preferably greater than 3500, the diameter of the fluid in Reynolds number calculating here adopts the hydraulic diameter of the reaction compartment of reaction zone.
Reaction zone of the present invention is undertaken heating or cooling by its outside surface.Reaction also can be carried out under the condition of thermal insulation, and this means that heating or cooling energy do not flow through the outside surface of reaction volume by engineering science measure, reaction is preferably implemented under thermal insulation.
The reaction product obtained by above condition has thermolability between 250-550 DEG C, therefore after phosgenation reaction, need reaction product to be cooled to rapidly less than 150 DEG C, avoid some less desirable side reactions occur, as 1, the pyrolysis of hexamethylene-diisocyanate, 1, the isomerization of hexamethylene-diisocyanate, also may occur 1 simultaneously, the further oligomerization of hexamethylene-diisocyanate or polyreaction, also there is further decomposition reaction etc. in the material that this polyreaction generates simultaneously.The mode temperature of reaction product being cooled to less than 150 DEG C has a lot, and the most frequently used mode adopts inert solvent in the reduction of single stage or multistage spray washing realization response product temperatur.
The inert solvent of spray washing of the present invention can be the hydrocarbon that optional halogen atom replaces, and optionally represents containing or does not contain, such as, one or two or more in chlorobenzene, dichlorobenzene, toluene and dimethylbenzene, one or both in preferred chlorine Benzene and Toluene; Also can use through interchanger cooling hexamethylene diisocyanate solution as inert solvent.In the process of spray washing, hexamethylene diisocyanate optionally enters inert solvent.Never containing 1, concentration and recovery inert solvent can be passed through in the gas (comprising the inert solvent of excessive phosgene, hydrogenchloride, inert media and spray washing) of hexamethylene-diisocyanate, phosgene reclaims in recovery measure subsequently, can a certain amount of HCl be contained, can return in reaction zone and proceed reaction as raw material.Obtained by spray washing 1, hexamethylene-diisocyanate solution is preferably by rectification and purification, obtain 1 of the hydrogenchloride photoreactive gas not containing physical bond (dissolving) and chemical bonding, hexamethylene-diisocyanate solution, and in further distilation steps, be separated into several material stream such as solvent, lower boiling by product, hexamethylene diisocyanate and high boiling product.
We find use in phosgenation reaction 1, the content of the low boiling component of 6-hexanediamine with by 1 of phosgenation reaction gained, certain relation is had between the colour stability of hexamethylene-diisocyanate, during content≤the 50mg/kg of especially low boiling component, obtain 1, hexamethylene-diisocyanate product under identical storage cycle has better colour stability, and its look rising range is starkly lower than amount of components having low boiling points under same reaction conditions and obtains the look rising range of product higher than 50mg/kg raw material.By controlling 1, the content of low boiling component in 6-hexanediamine, decrease the new impurity that low boiling component produces due to instability under gas phase phosgenation method high temperature, low boiling component can be reduced with the product assay after phosgene reaction simultaneously, more decrease other side reactions caused due to the existence of low boiling component in phosgenation reaction process, decrease 1, the content of impurity and kind in hexamethylene-diisocyanate reaction product, reduce the difficulty of separation and purification, the hexamethylene diisocyanate after separation and purification is made to have good colour stability.
Embodiment:
The following examples to being further described method provided by the present invention, but will the invention is not restricted to listed embodiment, also should be included in other any known changes in right of the present invention.
The test of the low boiling component of 1,6-hexanediamine can be measured by gas-chromatography, and measuring method is as follows: utilize Agilent 7890A gas chromatograph for determination, and chromatographic column model is J & W112-2112CAM15m, 0.25mm, 0.25 μm; Detector is fid detector, injector temperature: 250 DEG C, column temperature heating schedule: after 60 DEG C of maintenance 2min, be warming up to 100 DEG C with the speed of 10 DEG C/min and keep 2min, then be warming up to 220 DEG C with the speed of 20 DEG C/min and keep 2min, detector temperature: 250 DEG C, relative content adopts area to be obtained by normalization method.
The control mode of the low boiling component of 1,6-hexanediamine can adopt the mode of underpressure distillation.Amount of components having low boiling points is 1 of 80-200mg/kg, 6-hexanediamine is raw material, the theoretical plate number of packing tower is 20, adopt the mode of continuous rectification to 1, 6-hexanediamine carries out purifying, 1, 6-hexanediamine is from the 5th piece of theoretical stage charging, adopt the mode of bubble point charging, tower top adopts fractional distillating tube, tower top pressure controls at 20Kpa, after purifying 1, 6-hexanediamine material is from side take-off, extraction position is in the middle of 17-18 block theoretical stage, column bottom temperature controls between 148-150 DEG C, by controlling the mode of trim the top of column and feed loading, obtain 1 of different amount of components having low boiling points, 6-hexanediamine.In 1,6-hexanediamine of operational condition and acquisition, the content of low boiling component is in table 1.
Amount of components having low boiling points result in 1,6-hexanediamine of table 1 operational condition and acquisition
| Sequence number | Reflux ratio | Load kg/h | Lower boiling content mg/kg |
| 1 | 3:1 | 800 | 45 |
| 2 | 6:1 | 600 | 20 |
| 3 | 10:1 | 400 | 10 |
The testing method reference standard ASTMD4663-10 of the hydrolysis chlorine of product hexamethylene diisocyanate.
The measuring method reference standard GB/T3143-1982 of the look of hexamethylene diisocyanate product number.
Embodiment 1
The content being fed to the tetrahydroazepine of 1,6-hexanediamine in reaction zone, 1-amino-2-cyano group-1-cyclopentenes and ACN is 20mg/kg.
Nitrogen and 1, (nitrogen and 1 after the mixing of 6-hexanediamine, the volume ratio of 6 hexanediamine gases is 0.5:1) photoreactive gas successive reaction in tubular reactor, 1, the feed pressure of 6-hexanediamine photoreactive gas is 0.25MPa, the feeding temperature of two kinds of incoming flows is 310 DEG C, and the absolute pressure of reaction zone is 0.09MPa, a little less than normal atmosphere.The mol ratio of phosgene and the charging of 1,6-hexanediamine is 6:1, and the temperature of reaction zone is 420 DEG C.Flow velocity is 70m/s, and average contact time is 2s, and Reynolds number is 5000.
After reaction product leaves reaction zone, enter process island, the pressure of process island is 0.08MPa, carry out spray washing with chlorobenzene, the hexamethylene diisocyanate solution obtained obtains not containing phosgene and HCl 1 after rectification and purification, hexamethylene-diisocyanate solution, and through rectifying separation purifying subsequently, the hexamethylene diisocyanate product obtained.By analysis, the content of its hydrolyzable chlorine is that 15mg/kg(is in hexamethylene diisocyanate quality), look number (a Hazen colour) is No. 5.The hexamethylene diisocyanate product obtained is carried out senile experiment at 50 DEG C, measures the colour stability of product, the results are shown in Table 2.
Embodiment 2
The content being fed to the tetrahydroazepine of 1,6-hexanediamine in reaction zone, 1-amino-2-cyano group-1-cyclopentenes and ACN is 10mg/kg, repeats embodiment 1, obtain hexamethylene diisocyanate product under identical experiment condition.
By analysis, the content of its hydrolyzable chlorine is that 15mg/kg(is in hexamethylene diisocyanate quality), look number (a Hazen colour) is No. 5.The hexamethylene diisocyanate obtained is carried out senile experiment at 50 DEG C, measures the stability of product colour, the results are shown in Table 2.
Embodiment 3
The content being fed to the tetrahydroazepine of 1,6-hexanediamine in reaction zone, 1-amino-2-cyano group-1-cyclopentenes and ACN is 45mg/kg, repeats embodiment 1, obtain hexamethylene diisocyanate product under identical experiment condition.
By analysis, the content of its hydrolyzable chlorine is that 20mg/kg(is in hexamethylene diisocyanate quality), look number (a Hazen colour) is No. 5.The hexamethylene diisocyanate obtained is carried out senile experiment at 50 DEG C, measures the stability of product colour, the results are shown in Table 2.
Comparative example 1
The content being fed to the tetrahydroazepine of 1,6-hexanediamine in reaction zone, 1-amino-2-cyano group-1-cyclopentenes and ACN is 85mg/kg, repeats embodiment 1, obtain hexamethylene diisocyanate product under identical experiment condition.
By analysis, the content of its hydrolyzable chlorine is that 30mg/kg(is in hexamethylene diisocyanate quality), look number (a Hazen colour) is No. 5.The hexamethylene diisocyanate obtained is carried out senile experiment at 50 DEG C, measures the stability of product colour, the results are shown in Table 2.
Comparative example 2
Hexamethylene diisocyanate product comparative example 1 obtained, adds 25mg/kg(in hexamethylene diisocyanate quality) BHT, at 50 DEG C, carry out senile experiment, measure the stability of product colour, the results are shown in Table 2.
Table 21, the colour stability result table of hexamethylene-diisocyanate
As can be seen from the above table, the raw material of embodiment 2 has minimum amount of components having low boiling points, and the hexamethylene diisocyanate product that embodiment 2 obtains has best colour stability, and embodiment 1 is taken second place, and third embodiment 3, but is all better than comparative example 1.After the hexamethylene diisocyanate product of comparative example 2(comparative example 1 adds BHT) colour stability compare ratio 1 and had obvious improvement, but its stability is just more or less the same with the stability of embodiment 3, is obviously worse than embodiment 1 and embodiment 2.
In sum, by controlling the content of the combination of lower boiling in 1,6-hexanediamine, the colour stability obtaining the look number of hexamethylene diisocyanate has had obvious improvement.
Although the present invention discloses as above with several preferred embodiment; so itself and be not used to limit the present invention; have in any art and usually know the knowledgeable; without departing from the spirit and scope of the present invention; when doing arbitrary change and retouching, therefore protection scope of the present invention is as the criterion as the appended claim person of defining.
Claims (19)
1. prepare 1 for one kind, the method of hexamethylene-diisocyanate, to have or under inertialess medium existent condition, 1,6-hexanediamine and phosgene carry out phosgenation reaction in the reaction region, it is characterized in that, the amount of components having low boiling points≤50mg/kg in described 1,6-hexanediamine, with 1,6-hexanediamine raw material weight meter, the low boiling component of described 1,6-hexanediamine comprises tetrahydroazepine, 1-amino-2-cyano group-1-cyclopentenes and ACN.
2. method according to claim 1, is characterized in that, the amount of components having low boiling points≤40mg/kg in described 1,6-hexanediamine, with 1,6-hexanediamine raw material weight meter.
3. method according to claim 2, is characterized in that, the amount of components having low boiling points≤30mg/kg in described 1,6-hexanediamine, with 1,6-hexanediamine raw material weight meter.
4. method according to claim 3, is characterized in that, the amount of components having low boiling points≤10mg/kg in described 1,6-hexanediamine, with 1,6-hexanediamine raw material weight meter.
5. the method according to any one of claim 1-4, is characterized in that, the HCl gas containing 0-10wt% in described phosgene.
6. method according to claim 5, is characterized in that, described inert media be selected from nitrogen, chlorobenzene and dichlorobenzene one or more.
7. the method according to any one of claim 1-4, is characterized in that, described phosgenation reaction carries out in the gas phase, and the gasification of 1,6-hexanediamine is carried out in advance, and 1,6-hexanediamine of the gas phase obtained dripless before entering reaction zone exists.
8. method according to claim 7, is characterized in that, the mol ratio of phosgene and 1,6-hexanediamine is 2-20:1.
9. method according to claim 8, is characterized in that, the mol ratio of phosgene and 1,6-hexanediamine is 4-10:1.
10. method according to claim 9, is characterized in that, the mol ratio of phosgene and 1,6-hexanediamine is 6-8:1.
11. methods according to Claim 8 described in-10 any one, it is characterized in that, the temperature of described reaction zone is 300-500 DEG C, and pressure is absolute pressure 0.05-0.3MPa, and enter the pressure height 0.002-0.2MPa of the pressure ratio reaction zone in 1,6-hexanediamine photoreactive gas feed line of reaction zone; The low 0.001-0.05MPa of pressure of the pressure ratio reaction zone of the process area adjoined with downstream, reaction zone.
12. methods according to claim 11, it is characterized in that, the temperature of described reaction zone is 350-450 DEG C, and pressure is absolute pressure 0.07-0.2MPa, and enter the pressure height 0.003-0.1MPa of the pressure ratio reaction zone in 1,6-hexanediamine photoreactive gas feed line of reaction zone; The low 0.003-0.02MPa of pressure of the pressure ratio reaction zone of the process area adjoined with downstream, reaction zone.
13. methods according to claim 12, is characterized in that, pressure is absolute pressure 0.09-0.18MPa.
14. methods according to claim 11, is characterized in that, the flow velocity that 1,6-hexanediamine photoreactive gas incoming flow stock enters reaction zone is 5-100m/s.
15. methods according to claim 14, is characterized in that, the flow velocity that 1,6-hexanediamine photoreactive gas incoming flow stock enters reaction zone is 10-80m/s.
16. methods according to claims 14 or 15, it is characterized in that, the average contact time of 1,6-hexanediamine photoreactive gas in reaction zone is 0.01-15s.
17. methods according to claim 16, is characterized in that, the average contact time of 1,6-hexanediamine photoreactive gas in reaction zone is 0.04-10s.
18. methods according to claim 17, is characterized in that, the average contact time of 1,6-hexanediamine photoreactive gas in reaction zone is 0.08-5s.
19. methods according to claim 16, described phosgenation reaction operates under thermal insulation.
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| CN113072512B (en) * | 2020-01-06 | 2022-11-08 | 万华化学集团股份有限公司 | Preparation method of polyisocyanate |
| EP3939960A1 (en) | 2020-07-15 | 2022-01-19 | Covestro Deutschland AG | Method for the recovery of diamines from aqueous mixtures |
| CN111848455B (en) * | 2020-08-17 | 2023-05-30 | 万华化学集团股份有限公司 | Method for reducing chromaticity of isocyanate product and automatic control method for gas phase extraction flow of isocyanate rectifying tower |
| EP4151618A1 (en) | 2021-09-20 | 2023-03-22 | Covestro Deutschland AG | Obtaining aliphatic amines from compositions |
| CN114149345B (en) * | 2021-12-09 | 2023-04-21 | 万华化学集团股份有限公司 | Method for preparing isocyanate |
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