CN114315648B - Method for reducing content of hydrolytic chlorine in isocyanate - Google Patents
Method for reducing content of hydrolytic chlorine in isocyanate Download PDFInfo
- Publication number
- CN114315648B CN114315648B CN202210023863.5A CN202210023863A CN114315648B CN 114315648 B CN114315648 B CN 114315648B CN 202210023863 A CN202210023863 A CN 202210023863A CN 114315648 B CN114315648 B CN 114315648B
- Authority
- CN
- China
- Prior art keywords
- isocyanate
- chlorine
- reducing
- content
- azide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Abstract
The invention relates to a method for reducing the content of hydrolytic chlorine in isocyanate, which comprises the following steps: (1) Dissolving isocyanate with high hydrolytic chlorine in a solvent, and adding an azide reagent; (2) raising the temperature for reaction for a period of time; (3) adding an adsorbent after cooling, stirring and filtering; and (4) distilling the filtrate under reduced pressure to obtain a product. The invention converts the acyl chloride impurities in the isocyanate into the isocyanate through a simple operation process, and separates out the generated chloride, thereby providing a method for reducing the content of the hydrolysis chlorine in the isocyanate, and having the advantages of safe operation, simple method and easy industrial production.
Description
Technical Field
The invention relates to the field of isocyanate, in particular to a method for reducing the content of hydrolytic chlorine in isocyanate.
Background
Isocyanate is one of important raw materials for preparing polyurethane materials, and is widely applied to the fields of various elastomers, foamed plastics, synthetic fibers, synthetic leather, coatings, heat-insulating materials, waterproof materials, shoe making and the like. The content of hydrolyzed chlorine is an important indicator of isocyanate production. Hydrolytic chlorine refers to the hydrolyzable chlorine atoms (also including bromine atoms) present in the isocyanate product and is introduced by a variety of chlorine-containing by-products.
The excessive content of the hydrolytic chlorine can deepen the color of the product and can also generate adverse effects on the production process of polyurethane and the overall quality control of the product. In some fields of application, these chlorine-containing impurities also participate in the reaction, which leads to poor thermal stability in the subsequent treatment process. After a plurality of purification processes in industrial production, chlorine-containing byproducts such as residual phosgene, aromatic solvent micromolecule halogenated impurities, tar macromolecule chlorinated impurities and the like in isocyanate can be separated. However, the boiling point of the acyl chloride impurities is close to that of the isocyanate, and a certain amount of residues still remain in the product even after repeated rectification. How to effectively reduce the content of the acyl chloride impurities is a problem which must be faced in the production and application of isocyanate products.
Patents CN 109761855A and CN 112225678A suggest that secondary amine or amide impurities in amine raw materials generate acyl chloride substances which are difficult to separate in the reaction, and thus put higher requirements on the purity of the amine substances; patent CN 106554293A teaches that the phosgene is purified because activated carbon remaining in the phosgene catalyzes the insertion reaction of isocyanate with carbamoyl chloride or phosgene to produce a carbamoyl chloride which is difficult to separate. This necessarily increases the production cost.
The content of hydrolysis chlorine can be reduced by heating the isocyanate at a temperature well above the decomposition temperature of the carbamoyl chloride while flowing inert gas is introduced. U.S. Pat. No. 3,989,871A describes the reduction of the content of the hydrolyzed chlorine of polymethylene polyphenyl polyisocyanates by feeding liquid polyisocyanate at 177-232 ℃ from top to bottom into a treatment tower and treating it with nitrogen in countercurrent from bottom to top. However, the ability to reduce the hydrolytic chlorine content of other isocyanates using only heat and inert gases is limited and reduces the yield of isocyanate.
Patent CN 101084187A describes two methods for reducing the content of chlorine in the hydrolysis of n-butyl isocyanate. One is to pass a stream of water-wet nitrogen through n-butyl isocyanate, shut off the nitrogen after the batch has been heated and held for a period of time, cool and filter. This process reduces the chlorine-containing compounds in the organic isocyanates relatively gently, but results in material losses. In another method, n-butyl isocyanate and Lewatit. SC 108 (cation exchange resin) are placed in a sealed container, heated and held for a certain period of time, and then filtered to remove the resin, and this method requires the use of a cation exchange resin in excess of 6% by mass of n-butyl isocyanate, and the object to be treated is targeted.
WO2005012236A1 proposes the preparation of a high-purity product (less than 10ppm of hydrolysable chlorine) from (meth) acryloyloxyalkyl isocyanates with a high content of hydrolysable chlorine (not more than 700 ppm) at a temperature of 110 ℃ to 160 ℃ in a mixture with an epoxy compound and an amine, followed by distillation with the addition of a polymerization inhibitor. The method is not suitable for isocyanate with higher hydrolytic chlorine content and has complex operation.
CN109336999A proposes preparing copolymer beads of styrene and stilbene, and treating with chloromethyl ether and hexamethylenetetramine to obtain white spherical acid acceptor for reducing the content of hydrolytic chlorine and acid in crude polymeric MDI product. CN112430295A proposes that a double-bond-containing silane coupling agent is used for pre-modifying nano silicon dioxide, and then vinyl pyridine and 9-octadecylamine containing specific basic functional groups are subjected to graft copolymerization with modified silicon dioxide, so that the silicon dioxide has the functions of treating hydrogen chloride and acyl chloride. This method of preparing the adsorbent requires the synthesis of a specific adsorbent and the operation of the activation process is cumbersome.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a simple treatment method, which can effectively reduce the content of hydrolysis chlorine in isocyanate products and improve the quality of isocyanate.
The invention adopts the following technical scheme:
a method for reducing the content of hydrolysable chlorine in an isocyanate, comprising the steps of:
(1) Dissolving isocyanate with high hydrolytic chlorine in a solvent, and adding an azide reagent;
(2) Raising the temperature for reaction for a period of time;
(3) Adding an adsorbent after cooling, stirring and filtering;
(4) And distilling the filtrate under reduced pressure to obtain the product.
The isocyanate is aromatic isocyanate and/or aliphatic isocyanate; preferably the aromatic isocyanate is Toluene Diisocyanate (TDI) and/or diphenylmethane diisocyanate (MDI); preferably, the aliphatic isocyanate is one or more of butyl isocyanate, hexamethylene Diisocyanate (HDI), cyclohexane diisocyanate (CHDI), m-xylylene isocyanate (XDI), and dimer acid diisocyanate (DDI).
The solvent is one or more of an ether solvent, a ketone solvent, an ester solvent, an aliphatic hydrocarbon solvent, an aromatic hydrocarbon solvent, formamide, hexamethylphosphoramide, N-dimethylformamide, N-dimethyl sulfoxide, acetonitrile, propionitrile and carbon disulfide; preferably, the ether solvent is one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, dioxane and tetrahydrofuran; preferably, the ketone solvent is one or more of methyl isobutyl ketone, cyclohexanone, toluene cyclohexanone, 4-methyl-2-pentanone, acetone and methyl ethyl ketone; preferably, the ester solvent is one or more of ethyl acetate, methyl acetate, propyl acetate, butyl acetate and dimethyl carbonate; preferably, the aliphatic hydrocarbon solvent is one or more of hexane, cyclohexane, heptane, cycloheptane, octane and petroleum ether; preferably, the aromatic hydrocarbon solvent is one or more of xylene, chlorobenzene, dichlorobenzene, benzene and toluene; further preferred are ethylene glycol dimethyl ether and acetonitrile. The amount of solvent used is 1 to 5 times, preferably 1 to 3 times, the mass of the isocyanate.
The azidation reagent is a metal salt; a catalyst is added together with the metal salt azide reagent, and the amount of the catalyst is 1 to 100 percent, preferably 30 to 50 percent of the mole number of the hydrolyzable chlorine atoms; the metal salt is preferably one or more of sodium salt, potassium salt, magnesium salt, calcium salt, and silver salt, and more preferably sodium azide.
The catalyst is quaternary ammonium salt; the quaternary ammonium salt is preferably one or more of tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, tetrabutylammonium chloride, trioctylmethylammonium chloride, dodecyltrimethylphosphonium chloride and tetradecyltrimethylammonium chloride, and tetrabutylammonium bromide is more preferably used.
The azidation reagent may also be an organic azidation reagent, preferably trimethylsilylazide and/or tetrabutylammonium azide.
The mole ratio of the hydrolyzable chlorine atom to the azide group in the high-hydrolysis chlorine isocyanate is 1 (1-10), preferably 1 (4-6).
The reaction temperature in the step (2) is 0-100 ℃, and preferably 25-80 ℃; the reaction time in step (2) is 2 to 48 hours, preferably 4 to 8 hours.
The adsorbent is one or more of magnesium silicate, activated carbon, activated clay, diatomite and activated alumina, preferably magnesium silicate; the amount of adsorbent used is 0.5 to 5%, preferably 1%, by mass of isocyanate.
The invention utilizes the nitridizing reagent to carry out substitution reaction with chlorine-containing impurities (especially acyl chloride impurities) introduced into hydrolytic chlorine, converts chlorine atoms into chlorides easy to separate, and separates the chlorides from isocyanate through filtration or distillation, thereby achieving the purpose of reducing the content of hydrolytic chlorine in the isocyanate. Meanwhile, acyl chloride substances which are difficult to remove react with the azide reagent and are converted into corresponding acyl azide compounds, and the acyl azide compounds are decomposed and rearrange molecular structures after being heated and are finally converted into isocyanate groups.
The method for reducing the content of the hydrolysis chlorine in the isocyanate is provided by converting the acyl chloride impurities in the isocyanate into the isocyanate and separating the generated chloride through a simple operation process, and has the advantages of safe operation, simple method and easy industrial production.
Detailed Description
The invention will now be further illustrated by means of specific examples.
Example 1
50.01g of 2,4-TDI (0.150 wt% of hydrolyzed chlorine) was put into a 250ml four-necked flask equipped with a mechanical stirrer, a thermometer, a reflux tube, a nitrogen inlet and a balloon, 50g of acetonitrile was added thereto, the mixture was stirred and dissolved, 0.20g of tetrabutylammonium bromide and 0.55g of sodium azide were added thereto, the mixture was heated to 80 ℃ to react for 4 hours, cooled to room temperature, 0.50 g of magnesium silicate was added thereto, stirred for 30 minutes, filtered to remove solids, and acetonitrile was distilled off under reduced pressure to obtain 49.3g of a transparent liquid, the yield was 98.6%, and the hydrolyzed chlorine was 0.0090wt%.
Example 2
40.20g of butyl isocyanate (1.833% by weight of hydrolyzed chlorine) was charged into a 250ml four-necked flask equipped with a mechanical stirrer, a thermometer, a reflux tube, a nitrogen inlet and a balloon, 120.41g of acetonitrile was charged and dissolved by stirring, 3.30g of tetrabutylammonium bromide and 8.10g of sodium azide were charged, the temperature was raised to 25 ℃ to react for 8 hours, the reaction mixture was cooled to room temperature, 0.40 g of magnesium silicate was charged and stirred for 30 minutes, after removing solids by filtration, acetonitrile was distilled off under reduced pressure to obtain 39.42g of a transparent liquid, the yield was 98.1% and the hydrolyzed chlorine was 0.0094% by weight.
Example 3
50.15g of CHDI (hydrolyzed chlorine) (0.120 wt%) was charged into a 250ml four-neck flask equipped with a mechanical stirrer, a thermometer, a reflux tube, a nitrogen inlet and a balloon, 150.05g of ethylene glycol dimethyl ether was added thereto, the mixture was stirred and dissolved, 0.16g of tetrabutylammonium bromide and 0.44g of sodium azide were added thereto, the mixture was reacted at 60 ℃ for 6 hours, cooled to room temperature, added with 0.50 g of magnesium silicate and stirred for 30 minutes, filtered to remove solids, and the ethylene glycol dimethyl ether was distilled off under reduced pressure to obtain 49.2g of a transparent liquid, the yield was 98.1% and the hydrolyzed chlorine was 0.0089wt%.
Example 4
49.8g of XDI (0.116 wt% of hydrolyzed chlorine), 100g of toluene and 0.75g of azidotrimethylsilane were charged into a 250ml four-necked flask equipped with a mechanical stirrer, a thermometer, a reflux tube, a nitrogen inlet and a balloon, and the mixture was stirred, heated to 60 ℃ to react for 6 hours, cooled to room temperature, added with 1.20 g of activated clay, stirred for 30 minutes, filtered to remove solids, and then distilled under reduced pressure to remove small molecular substances, whereby 48.8g of a transparent liquid was obtained, the yield was 98.0%, and the hydrolyzed chlorine was 0.0081wt%.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (18)
1. A method for reducing the content of hydrolysable chlorine in isocyanates, comprising the steps of:
(1) Dissolving isocyanate with high hydrolytic chlorine in a solvent, and adding an azide reagent;
(2) Raising the temperature for reaction for a period of time;
(3) Adding an adsorbent after cooling, stirring and filtering;
(4) Distilling the filtrate under reduced pressure to obtain a product;
the azide reagent in the step (1) is a metal salt or an organic azide reagent; a catalyst is also added together with the metal salt nitridizing reagent, and the catalyst is quaternary ammonium salt;
the reaction temperature in the step (2) is 0-100 ℃;
the adsorbent in the step (3) is one or more of magnesium silicate, activated carbon, activated clay, diatomite and activated alumina;
the metal salt azide reagent is one or more of sodium azide, potassium azide, magnesium azide, calcium azide and silver azide; the organic azide reagent is trimethylsilyl azide and/or tetrabutylammonium azide; the quaternary ammonium salt is one or more of tetrabutylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, tetrabutylammonium chloride, trioctylmethylammonium chloride, dodecyltrimethylphosphonium chloride and tetradecyltrimethylammonium chloride.
2. The method for reducing the content of hydrolyzed chlorine in isocyanate according to claim 1, wherein the isocyanate in step (1) is an aromatic isocyanate and/or an aliphatic isocyanate.
3. The method for reducing the content of hydrolyzed chlorine in isocyanate according to claim 2, wherein the aromatic isocyanate is toluene diisocyanate and/or diphenylmethane diisocyanate; the aliphatic isocyanate is one or more of butyl isocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, m-phenylene diisocyanate and dimer acid diisocyanate.
4. The method for reducing the content of chlorine hydride in isocyanate according to claim 1, wherein the solvent in step (1) is one or more selected from the group consisting of ether solvents, ketone solvents, ester solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, formamide, hexamethylphosphoramide, N-dimethylformamide, N-dimethylsulfoxide, acetonitrile, propionitrile, and carbon disulfide.
5. The method for reducing the content of hydrolyzed chlorine in isocyanate according to claim 4, wherein the ether solvent is one or more selected from the group consisting of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, isopropyl ether, n-butyl ether, diphenyl ether, dioxane, and tetrahydrofuran; the ketone solvent is one or more of methyl isobutyl ketone, cyclohexanone, toluene cyclohexanone, 4-methyl-2-pentanone, acetone and methyl ethyl ketone; the ester solvent is one or more of ethyl acetate, methyl acetate, propyl acetate, butyl acetate and dimethyl carbonate; the aliphatic hydrocarbon solvent is one or more of hexane, cyclohexane, heptane, cycloheptane, octane and petroleum ether; the aromatic hydrocarbon solvent is one or more of xylene, chlorobenzene, dichlorobenzene, benzene and toluene.
6. The method for reducing the content of the hydrolyzed chlorine in the isocyanate according to claim 1 or 4, wherein the solvent is ethylene glycol dimethyl ether or acetonitrile.
7. The method for reducing the content of hydrolyzable chlorine in isocyanate according to claim 1, wherein the amount of solvent used in step (1) is 1 to 5 times the mass of isocyanate.
8. The method for reducing the content of hydrolyzed chlorine in isocyanate according to claim 1 or 7, wherein the amount of the solvent used in the step (1) is 1 to 3 times the mass of the isocyanate.
9. The method for reducing the content of hydrolyzable chlorine in isocyanate according to claim 1, wherein the amount of the catalyst used in step (1) is 1 to 100% by mole of the hydrolyzable chlorine atom.
10. The method for reducing the content of hydrolyzable chlorine in isocyanate according to claim 1 or 9, wherein the amount of the catalyst used in step (1) is 30 to 50% by mole of the hydrolyzable chlorine atom.
11. The method for reducing the content of hydrolyzable chlorine in isocyanate according to claim 1, wherein the metal salt in step (1) is sodium azide.
12. The method for reducing the content of hydrolyzed chlorine in isocyanate according to claim 1, wherein the quaternary ammonium salt is tetrabutylammonium bromide.
13. The method for reducing the content of hydrolyzable chlorine in isocyanate according to claim 1, wherein the molar ratio of hydrolyzable chlorine atoms to azide groups in the high-hydrolyzable chlorine isocyanate in step (1) is 1 (1-10).
14. The method for reducing the content of hydrolyzable chlorine in isocyanate according to claim 1 or 13, wherein the molar ratio of hydrolyzable chlorine atoms to azide groups in the high-hydrolyzable chlorine isocyanate in step (1) is 1 (4-6).
15. The method for reducing isocyanate hydrolytic chlorine according to claim 1, characterized in that: the reaction temperature in the step (2) is 25-80 ℃; the reaction time in the step (2) is 2 to 48 hours.
16. The method for reducing isocyanate hydrolytic chlorine according to claim 1 or 15, characterized in that: the reaction time in the step (2) is 4 to 8 hours.
17. The method for reducing isocyanate hydrolysis chlorine according to claim 1, wherein: the dosage of the adsorbent in the step (3) is 0.5-5% of the mass of the isocyanate.
18. The method for reducing isocyanate hydrolysis chlorine according to claim 1 or 17, wherein: the amount of the adsorbent used in the step (3) is 1% of the mass of the isocyanate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210023863.5A CN114315648B (en) | 2022-01-11 | 2022-01-11 | Method for reducing content of hydrolytic chlorine in isocyanate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210023863.5A CN114315648B (en) | 2022-01-11 | 2022-01-11 | Method for reducing content of hydrolytic chlorine in isocyanate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114315648A CN114315648A (en) | 2022-04-12 |
| CN114315648B true CN114315648B (en) | 2023-03-03 |
Family
ID=81026923
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210023863.5A Active CN114315648B (en) | 2022-01-11 | 2022-01-11 | Method for reducing content of hydrolytic chlorine in isocyanate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114315648B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115850117A (en) * | 2022-11-15 | 2023-03-28 | 黎明化工研究设计院有限责任公司 | Method for preparing 1,4-cyclohexane diisocyanate |
| CN115894298A (en) * | 2022-12-14 | 2023-04-04 | 甘肃银光聚银化工有限公司 | Post-treatment method for reducing hydrolysis chlorine of 1, 5-pentamethylene diisocyanate |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1064074A (en) * | 1991-01-28 | 1992-09-02 | 陶氏化学公司 | Reduce the method for hydrolyzable chloride in the tolylene diisocyanate |
| DE19922572A1 (en) * | 1999-05-17 | 2000-11-23 | Bayer Ag | Process for the purification of organic isocyanates, the organic isocyanates thus purified and their use |
| CN1934075A (en) * | 2004-03-25 | 2007-03-21 | 昭和电工株式会社 | Method for producing (meth)acrylate derivative having isocyanate group |
| CN101805270A (en) * | 2010-03-31 | 2010-08-18 | 北京金方博源科技发展有限公司 | Aliphatic diisocyanate and preparation method and purposes thereof |
| EP2829533A1 (en) * | 2013-07-26 | 2015-01-28 | Bayer MaterialScience AG | Method for making isocyanates |
| CN106554293A (en) * | 2015-09-24 | 2017-04-05 | 万华化学集团股份有限公司 | A kind of method for preparing colourless or light polyisocyanates |
| CN110218163A (en) * | 2019-05-20 | 2019-09-10 | 江苏蓝丰生物化工股份有限公司 | The synthetic method of n-butyl isocyanate |
| CN110396057A (en) * | 2019-07-16 | 2019-11-01 | 万华化学（宁波）有限公司 | A method of preparing the isocyanates of low chlorine content |
| CN112239416A (en) * | 2020-11-02 | 2021-01-19 | 万华化学集团股份有限公司 | Preparation process of toluene diisocyanate with low chlorine and bromine hydrolysis |
-
2022
- 2022-01-11 CN CN202210023863.5A patent/CN114315648B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1064074A (en) * | 1991-01-28 | 1992-09-02 | 陶氏化学公司 | Reduce the method for hydrolyzable chloride in the tolylene diisocyanate |
| DE19922572A1 (en) * | 1999-05-17 | 2000-11-23 | Bayer Ag | Process for the purification of organic isocyanates, the organic isocyanates thus purified and their use |
| CN1934075A (en) * | 2004-03-25 | 2007-03-21 | 昭和电工株式会社 | Method for producing (meth)acrylate derivative having isocyanate group |
| CN101805270A (en) * | 2010-03-31 | 2010-08-18 | 北京金方博源科技发展有限公司 | Aliphatic diisocyanate and preparation method and purposes thereof |
| EP2829533A1 (en) * | 2013-07-26 | 2015-01-28 | Bayer MaterialScience AG | Method for making isocyanates |
| CN106554293A (en) * | 2015-09-24 | 2017-04-05 | 万华化学集团股份有限公司 | A kind of method for preparing colourless or light polyisocyanates |
| CN110218163A (en) * | 2019-05-20 | 2019-09-10 | 江苏蓝丰生物化工股份有限公司 | The synthetic method of n-butyl isocyanate |
| CN110396057A (en) * | 2019-07-16 | 2019-11-01 | 万华化学（宁波）有限公司 | A method of preparing the isocyanates of low chlorine content |
| CN112239416A (en) * | 2020-11-02 | 2021-01-19 | 万华化学集团股份有限公司 | Preparation process of toluene diisocyanate with low chlorine and bromine hydrolysis |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114315648A (en) | 2022-04-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114315648B (en) | Method for reducing content of hydrolytic chlorine in isocyanate | |
| JP5599129B2 (en) | Isocyanate production method | |
| CN110982038B (en) | Polyurethane resin and preparation method thereof | |
| PL180229B1 (en) | Method of obtaining isocyanates | |
| CN1125718A (en) | Process for the preparation of aliphatic polyisocyanates | |
| KR101318828B1 (en) | Process of preparing xylylene diisocyanates, their reaction intermediates and process of preparing them | |
| US4193932A (en) | Process for preparing organic isocyanates | |
| US3471543A (en) | Sequential production of polyisocyanate compositions | |
| US4745216A (en) | Process for the production of polyisocyanates | |
| US3179680A (en) | Purification of organic isocyanates | |
| GB2029413A (en) | Preparation of organic mono- and polyisocyanates | |
| US4597909A (en) | Process for the production of polyisocyanates | |
| US3210395A (en) | Method of making toluene diisocyanate /x/cz e excejjx | |
| JP2004262835A (en) | Method for producing aromatic isocyanate | |
| US2831012A (en) | Chemical process | |
| JP2915784B2 (en) | Purification method of aliphatic isocyanate | |
| KR20070084595A (en) | Method for producing polyisocyanates | |
| US3282975A (en) | Process for producing stable, undistilled tolylene diisocyanate compositions | |
| JP4307588B2 (en) | Process for producing aliphatic isocyanate compounds | |
| JP2596650B2 (en) | Method for producing isocyanate compound | |
| US3184494A (en) | Process for producing organic isocyanates | |
| JP2804132B2 (en) | Purification method of carbamate | |
| RU2750198C1 (en) | Method for producing methylene diphenyl diisocyanate | |
| US3169141A (en) | Process for the recovery of organic | |
| JPS62221661A (en) | Aliphatic diisocyanates and use for manufacturing polyurethane plastic |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |