CN107235935A - A kind of preparation method of solventless method alkyl ketene dimer (AKD) - Google Patents
A kind of preparation method of solventless method alkyl ketene dimer (AKD) Download PDFInfo
- Publication number
- CN107235935A CN107235935A CN201710462641.2A CN201710462641A CN107235935A CN 107235935 A CN107235935 A CN 107235935A CN 201710462641 A CN201710462641 A CN 201710462641A CN 107235935 A CN107235935 A CN 107235935A
- Authority
- CN
- China
- Prior art keywords
- tertiary amine
- akd
- ketene dimer
- alkyl ketene
- preparation
- 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.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D305/00—Heterocyclic compounds containing four-membered rings having one oxygen atom as the only ring hetero atoms
- C07D305/02—Heterocyclic compounds containing four-membered rings having one oxygen atom as the only ring hetero atoms not condensed with other rings
- C07D305/10—Heterocyclic compounds containing four-membered rings having one oxygen atom as the only ring hetero atoms not condensed with other rings having one or more double bonds between ring members or between ring members and non-ring members
- C07D305/12—Beta-lactones
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The present invention provides a kind of method that solventless method prepares alkyl ketene dimer (AKD), this method is using fat acyl chloride and tertiary amine as raw material, for the viscosity produced by reduction course of reaction, make tertiary amine excessive, and take during the course of the reaction using the method for adding crystal seed.Reactant mixture is used the modes such as filtering, distillation or acid extraction to carry out isolated alkyl ketene dimer by reaction after terminating.This method solve with benzene or toluene as solvent prepare alkyl ketene dimer when caused pollution and problem of solvent residual.
Description
Technical field
The present invention relates to the method that one kind prepares alkyl ketene dimer (AKD) as raw material using tertiary amine and fat acyl chloride,
The granular size of crystal seed generation Amine from Tertiary Amine Hydrochloride to increase is added in initial feed and in course of reaction, while reducing reaction
The viscosity of mixture.The involved preparation method of invention prepares alkyl ketene dimer for solventless method.
Background technology
Alkyl ketene dimer (AKD) is a kind of neutral paper sizing agent, has many advantages compared to acid accumulator size.Its
Preparation method is that, using tertiary amine as acid binding agent, the hydrogen chloride generation ketenes intermediate in removing fat acyl chloride, ketenes intermediate continues
Dimerization reaction obtains AKD.In course of reaction, due to the generation of Amine from Tertiary Amine Hydrochloride so that reactant mixture viscosity is very high, reaction
Heat is difficult to timely removal, and accessory substance increases.Need to add atent solvent in reactant mixture viscosity, course of reaction to reduce, often
Solvent is benzene or toluene.The addition of solvent is often very high, and general 1 part of acyl chlorides at least needs to add 4-8 parts of solvents.Such as
The addition of this organic solvent at high proportion, not only causes very big difficulty to AKD post processings, also makes to remain unavoidably in AKD products
A small amount of organic solvent (AKD products per ton at least contain 1-6kg toluene), the solvent of these residuals has been brought into each ring of copy paper
Section, and as AKD emulsions are brought into paper, environmental and human health impacts are brought with unpredictable influence.With people's ring
The raising of border consciousness, country it is also proposed more strict requirements to the content of toluene in AKD, for industrial enterprise, compel to be essential
A kind of substitution method is wanted, to reduce solvent load.
The content of the invention
For problem present in alkyl ketene dimer preparation process, the present invention provides a kind of solventless method and prepares alkyl
Ketene dimer, i.e., using tertiary amine and fat acyl chloride as raw material, and make tertiary amine somewhat excessive, excessive tertiary amine plays the work of solvent
With, meanwhile, add crystal seed in reaction initiation material and in course of reaction.It has been proved that add after crystal seed, Amine from Tertiary Amine Hydrochloride
Granularity can effectively become big, and reactant mixture viscosity is effectively reduced, and the environment dirt that organic solvent is brought is avoided well
Dye and healthy hidden danger, are a kind of methods being worthy to be popularized, with good economic benefit and environmental benefit.
The technical solution adopted in the present invention is：
(1) tertiary amine and first crystal seed are added in reactor, stirred, the property according to tertiary amine and fat acyl chloride will be mixed
Compound is heated to 35-60 DEG C；
(2) fat acyl chloride is added into mixture, the charging rate of acyl chlorides is controlled, it is impossible to too fast, prevents produced uncle
Amine hydrochlorate crystal grain is too small, and viscosity increase, the charging rate of control fat acyl chloride makes the concentration of Amine from Tertiary Amine Hydrochloride in the mixture
Pace of change is less than 2% (wt)/min.Fat acyl chloride feeding manner can use continuous feed, it would however also be possible to employ the side of batch feed
Formula, if in the case of being difficult to control according to feedstock property reaction speed, can preferentially select the mode of batch feed；
(3) crystal seed is preferentially added portionwise, and the amount of every batch of addition crystal seed can be with identical, can also be different, depending on generated tertiary amine
Depending on the crystal formation and grain size of hydrochloride；
(4) acyl chlorides charging is finished, and keeps 40-90 DEG C of reaction temperature, continues to react 1-6hr；
(7) after completion of the reaction, the dissolubility according to raw material proportioning and AKD in tertiary amine, can be divided using three kinds of modes
From：
If a. the raw material proportioning of tertiary amine and acyl chlorides is higher, when mixture viscosity is less than 1000mPa.s, first mixture can be entered
Row filtering, filters out Amine from Tertiary Amine Hydrochloride, the mixture of AKD and tertiary amine then is carried out into vacuum distillation, so that isolated AKD；
If b. the raw material proportioning of tertiary amine and acyl chlorides is higher, mixture viscosity is less than 1000mPa.s, and AKD is in tertiary amine
When solubility is smaller, first mixture can be filtered, filter out Amine from Tertiary Amine Hydrochloride, then the mixture of AKD and tertiary amine is cooled,
AKD solidifications are separated out, and filtering is separable to obtain AKD；
If c. the raw material proportioning of tertiary amine and acyl chlorides is relatively low, when mixture viscosity is larger, the mode of acid extraction can be taken, to mixed
Hydrochloric acid or sulfuric acid, prioritizing selection hydrochloric acid are added in compound.Concrete mode is：Reaction product is heated to 60-90 DEG C under stirring, plus
Enter hydrochloric acid, depending on stirring 1-20min, amount of the concentration of hydrochloric acid according to remaining tertiary amine so that the tertiary amine hydrochloric acid being ultimately formed
The concentration of salt in aqueous is between 30-70% (wt), and hydrochloric acid is somewhat excessive, makes the mol ratio of HCl and tertiary amine according to calculating
For between 1.1-2.Then, stand, layering separates upper strata oil reservoir；
Oil reservoir AKD is washed with hot water, the impurity of course of reaction and water-washing process is removed.Concrete mode is a certain amount of
Hot water add after, stir 5-40min, stand, layering, obtain AKD；
Product AKD is dried in vacuo at 35-90 DEG C, and drying time is 20min-2hr.
AKD products obtained by the present invention are pale yellow waxy solid, and course of reaction is without organic solvents such as benzene and toluenes
Use, product purity is high, resulting alkyl ketene dimer can be used for packaging material for food as the sizing agent of safety.
Embodiment
Below in conjunction with specific implementation example, the present invention will be described in detail：
Tertiary amine and first crystal seed are added in reactor, stirred, the property according to tertiary amine and fat acyl chloride will be mixed
Thing is heated to 35-60 DEG C, controls charging rate, fat acyl chloride is added into mixture, course of reaction controlling reaction temperature is in 40-
Between 90 DEG C, crystal seed is added by batch in course of reaction, acyl chlorides charging is finished, and keeps reaction temperature, continues to react 1-6hr.Reaction
After finishing, according to the dissolubility of raw material proportioning and AKD in tertiary amine, it may be selected using distillation, filtering and three kinds of modes of acid extraction
Carry out isolated AKD.
Embodiment 1 (comparative example)
106.3g triethylamines and 387g toluene are added in reactor, stirring, are gradually heating to 50 DEG C.By 303g stearoyls
Chlorine, which is gradually added into, to be added in reactant mixture, and control rate of addition is in 5g/min.Stearyl chloride, which is added, to be finished, maintenance reaction temperature
Degree continues to react 3hr at 55 DEG C.
Filter while hot, filter out triethylamine hydrochloride, filtrate carries out vacuum distillation at 75 DEG C, steams toluene, obtain AKD productions
Thing.Infrared detection AKD purity is 88.5%.
Embodiment 2
152g triethylamines and 1g crystal seeds are added to reactor simultaneously, stir, are heated to 50 DEG C, 303g stearyl chloride controls
Charging rate processed is added gradually to be reacted in reactor in 5g/min, and crystal seed is added portionwise, i.e., when stearyl chloride feed to
During 101g, second batch 2g crystal seeds are added in reactor；After 202g stearyl chlorides are added, the 3rd crowd of crystal seed 2g is added.Stearoyl
Chlorine charging is finished, 65 DEG C of controlling reaction temperature, continues to react 2.5hr.
Reactant mixture is warming up to 75 DEG C, and the hydrochloric acid of 91g mass concentrations 30% is added in mixture, rapid stirring
10min, stratification 20min, separate aqueous layer and oil reservoir, oil reservoir, in carrying out washing 20min at 75 DEG C, are stood with 200ml hot water
Layering, removes water layer, and oil reservoir AKD products are dried in vacuo 2hr in 75 DEG C.Infrared detection, AKD purity is 91.63%.
Embodiment 3
405g triethylamines and 0.8g crystal seeds are added to reactor simultaneously, stir, are heated to 50 DEG C, 303g stearyl chlorides
Control charging rate is added gradually to be reacted in reactor in 5g/min, and crystal seed is added portionwise, i.e., when stearyl chloride feeds
During to 101g, second batch 1.6g crystal seeds are added in reactor；After 202g stearyl chlorides are added, the 3rd crowd of crystal seed 1.6g is added.
Stearyl chloride charging is finished, 60 DEG C of controlling reaction temperature, continues to react 2hr.
Reactant mixture is filtered, and filters out triethylamine hydrochloride solid, filtrate is cooled to room temperature, is filtered, is obtained AKD solids,
Residual filtrate is reserved for the raw material of lower secondary response.Gained AKD is through infrared detection, and purity is 92.15%.
Embodiment 4
405g triethylamines and 0.8g crystal seeds are added to reactor simultaneously, stir, are heated to 50 DEG C, 303g stearyl chlorides
Control charging rate is added gradually to be reacted in reactor in 5g/min, and crystal seed is added portionwise, i.e., when stearyl chloride feeds
During to 101g, second batch 1.6g crystal seeds are added in reactor；After 202g stearyl chlorides are added, the 3rd crowd of crystal seed 1.6g is added.
Stearyl chloride charging is finished, 60 DEG C of controlling reaction temperature, continues to react 2hr.
Reactant mixture is filtered, and filters out triethylamine hydrochloride solid, filtrate steams triethylamine in 70 DEG C of vacuum distillations.It is red
Outer detection, AKD purity is 91.95%.
Embodiment 5
140g diethyl methyl amines and 1.2g crystal seeds are added to reactor simultaneously, stir, and are heated to 50 DEG C, 303g is stearic
Acyl chlorides control charging rate is added gradually to be reacted in reactor in 5g/min, and crystal seed is added portionwise, that is, works as stearyl chloride
When charging is to 101g, second batch 2.4g crystal seeds are added in reactor；After 202g stearyl chlorides are added, the 3rd crowd of crystal seed 2.4g adds
Enter.Stearyl chloride charging is finished, 65 DEG C of controlling reaction temperature, continues to react 2.5hr.
Reactant mixture is warming up to 75 DEG C, and the hydrochloric acid of 91g mass concentrations 30% is added in mixture, rapid stirring
10min, stratification 20min, separate aqueous layer and oil reservoir, oil reservoir, in carrying out washing 20min at 75 DEG C, are stood with 200ml hot water
Layering, removes water layer, and oil reservoir AKD products are dried in vacuo 2hr in 75 DEG C.Infrared detection, AKD purity is 91.45%.
Embodiment 6
201g tripropyl amine (TPA)s and 0.6g crystal seeds are added to reactor simultaneously, stir, are heated to 55 DEG C, 303g stearyl chlorides
Control charging rate is added gradually to be reacted in reactor in 5g/min, and crystal seed is added portionwise, i.e., when stearyl chloride feeds
During to 101g, second batch 1g crystal seeds are added in reactor；After 202g stearyl chlorides are added, the 3rd crowd of crystal seed 1g is added.It is stearic
Acyl chlorides charging is finished, 65 DEG C of controlling reaction temperature, continues to react 2.5hr.
Reactant mixture is warming up to 75 DEG C, and the hydrochloric acid of 91g mass concentrations 30% is added in mixture, rapid stirring
10min, stratification 20min, separate aqueous layer and oil reservoir, oil reservoir, in carrying out washing 20min at 75 DEG C, are stood with 200ml hot water
Layering, removes water layer, and oil reservoir AKD products are dried in vacuo 2hr in 75 DEG C.Infrared detection, AKD purity is 92.45%.
Claims (10)
1. a kind of preparation method of alkyl ketene dimer (AKD), it is characterised in that preparation includes following process：
(1) tertiary amine and crystal seed are added in reactor, are heated to certain temperature；
(2) charging rate is controlled, fat acyl chloride is slowly added to；
(3) with the progress of reaction, crystal seed is gradually added in reaction system；
(4) raw material is added and finished, and maintenance reaction temperature continues to react a period of time；
(5) after completion of the reaction, the dissolubility according to raw material proportioning and AKD in tertiary amine, using three kinds of modes can separate
To AKD：A. distillation under vacuum；B. filtration method；C. acid extraction method.
2. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (1), first
First initial raw material is heated, temperature is heated to for 35-60 DEG C, preferably 40-50 DEG C.
3. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (2), control
The charging rate of fat acyl chloride processed makes the change in concentration speed of Amine from Tertiary Amine Hydrochloride in the mixture be less than 2% (wt)/min, preferentially
Selection is less than 0.5% (wt)/min, and moment observation system viscosity change, notices that viscosity should not be raised too fast.
4. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (2), fat
The feeding manner of fat acyl chlorides can use continuous feed mode, it would however also be possible to employ fed-batch mode, if being reacted according to feedstock property
In the case that speed is whard to control, the mode of batch feed can be preferentially selected.
5. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that the step (1) and (2)
In, the mol ratio of tertiary amine and fat acyl chloride is 1.02~6, preferably 2-4, excessive tertiary amine is also served as reactant molten
Agent.
6. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (3), brilliant
Kind be preferably added portionwise, add the total amount of crystal seed at least in more than 0.1% (wt), the upper limit according to the crystal formation of Amine from Tertiary Amine Hydrochloride with
And equipment used is no more than 50% (wt).
7. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (4), when
After the completion of acyl chlorides charging, maintenance reaction temperature (40-90 DEG C, preferably 50-70 DEG C) is answered to continue to react 1-6hr, preferably 2-5hr.
8. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (5), instead
After should finishing, according to the dissolubility of raw material proportioning and AKD in tertiary amine, it can be separated using three kinds of modes：
If a. the raw material proportioning of tertiary amine and acyl chlorides is higher, when mixture viscosity is less than 1000mPa.s, first mixture can be carried out
Filter, filters out Amine from Tertiary Amine Hydrochloride, the mixture of AKD and tertiary amine then is carried out into vacuum distillation, so that isolated AKD；
If b. the raw material proportioning of tertiary amine and acyl chlorides is higher, mixture viscosity is less than 1000mPa.s, and dissolvings of the AKD in tertiary amine
When degree is smaller, first mixture can be filtered, filter out Amine from Tertiary Amine Hydrochloride, then the mixture of AKD and tertiary amine cools, filtered out
AKD solids, filtrate (predominantly AKD and tertiary amine) is reusable；
If c. the raw material proportioning of tertiary amine and acyl chlorides is relatively low, when mixture viscosity is larger, the mode of acid extraction can be taken, to mixture
Middle addition hydrochloric acid or sulfuric acid, prioritizing selection hydrochloric acid.Concrete mode is：Reaction product is heated to 60-90 DEG C under stirring, salt is added
Acid, stirs 1-20min, preferably 4-10min, depending on amount of the concentration of hydrochloric acid according to remaining tertiary amine so that be ultimately formed
The concentration of Amine from Tertiary Amine Hydrochloride in aqueous is between 30-70% (wt), preferably 40-60% (wt), and hydrochloric acid is somewhat excessive, according to
Calculate make HCl and tertiary amine mol ratio be 1.1-2 between, preferably 1.3-1.5.Then, stand, layering takes oil reservoir；
Oil reservoir AKD is washed with hot water, the impurity of course of reaction and water-washing process is removed.Concrete mode is a certain amount of heat
After water is added, 5-40min, preferably 10-15min are stirred, stands, be layered, obtain AKD；
Product AKD is then dried in vacuo, and 35-90 DEG C of drying temperature, the time is 20min-2hr, preferably 30min to 1hr.
9. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (1), institute
The molecular formula of the tertiary amine used is R1R2R3N, wherein R1、R2、R3For separate alkyl, alkenyl, aralkyl or cycloalkyl, carbon
Atom number can be from 1 to 10, and total carbon atom number should make tertiary amine be liquid, prioritizing selection fatty amine.For example, selectable tertiary amine
Can be triethylamine, N, N- diethyl methyl amines, N, N- dimethyl cyclohexyl amines, tripropyl amine (TPA), nafoxidine, etc., or select several uncles
The mixture of amine.Economically consider, triethylamine can prioritizing selection.
10. the preparation method of alkyl ketene dimer according to claim 1, it is characterised in that in the step (2),
The number of carbon atom can reach 30, preferably 12-22 carbon atom in the fat acyl chloride used.Fat acyl chloride can be saturation
Fat acyl chloride or unsaturated fat acyl chlorides, such as lauroyl chloride, stearyl chloride, eicosane acyl chlorides, palmitoyl chloride, oleic acid acyl chlorides, etc..
, can prioritizing selection stearyl chloride, lauroyl chloride from the point of view of economy.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710462641.2A CN107235935A (en) | 2017-06-19 | 2017-06-19 | A kind of preparation method of solventless method alkyl ketene dimer (AKD) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710462641.2A CN107235935A (en) | 2017-06-19 | 2017-06-19 | A kind of preparation method of solventless method alkyl ketene dimer (AKD) |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN107235935A true CN107235935A (en) | 2017-10-10 |
Family
ID=59986297
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710462641.2A Pending CN107235935A (en) | 2017-06-19 | 2017-06-19 | A kind of preparation method of solventless method alkyl ketene dimer (AKD) |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107235935A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113956217A (en) * | 2021-11-09 | 2022-01-21 | 万华化学集团股份有限公司 | Solvent-free preparation method of alkyl ketene dimer AKD |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5399774A (en) * | 1993-02-22 | 1995-03-21 | Eka Nobel Ab | Process for the production of ketene dimers |
| CN1118157A (en) * | 1993-02-22 | 1996-03-06 | 埃卡·诺贝尔公司 | A process for the production of ketene dimers |
| JP2010150170A (en) * | 2008-12-24 | 2010-07-08 | Nof Corp | Method for producing alkyl ketene dimer |
| CN103102333A (en) * | 2013-01-25 | 2013-05-15 | 甘肃银光聚银化工有限公司 | Production method for alkyl ketene dimer |
-
2017
- 2017-06-19 CN CN201710462641.2A patent/CN107235935A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5399774A (en) * | 1993-02-22 | 1995-03-21 | Eka Nobel Ab | Process for the production of ketene dimers |
| CN1118157A (en) * | 1993-02-22 | 1996-03-06 | 埃卡·诺贝尔公司 | A process for the production of ketene dimers |
| JP2010150170A (en) * | 2008-12-24 | 2010-07-08 | Nof Corp | Method for producing alkyl ketene dimer |
| CN103102333A (en) * | 2013-01-25 | 2013-05-15 | 甘肃银光聚银化工有限公司 | Production method for alkyl ketene dimer |
Non-Patent Citations (1)
| Title |
|---|
| 吴佩琛: "中性抄纸施胶剂——十六烷基烯酮二聚体的合成", 《中国造纸》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113956217A (en) * | 2021-11-09 | 2022-01-21 | 万华化学集团股份有限公司 | Solvent-free preparation method of alkyl ketene dimer AKD |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| DE69413986T2 (en) | CHLORINE PROCEDURE | |
| CN108101850A (en) | A kind of method for improving 5-acetoacetamido benzimidazolone quality | |
| CN107235935A (en) | A kind of preparation method of solventless method alkyl ketene dimer (AKD) | |
| EP1341722B1 (en) | Method for producing trichlorosilane | |
| DE3881012T2 (en) | Process for the production of 4,4'-diaminodicyclohexylmethane with a low trans-trans isomer content by catalytic hydrogenation of 4,4'-diaminodiphenylmethane. | |
| DE69819948T2 (en) | Process for the production of monosilanes | |
| CN107915631A (en) | A kind of post-processing approach of 4 chloro methyl acetoacetates of continuous synthesis | |
| DE19943844A1 (en) | Process for the production of carboxylic acid chlorides | |
| CN107382913A (en) | A kind of method that solventless method prepares alkyl ketene dimer | |
| DE60314625T2 (en) | CONTINUOUS METHOD FOR THE CATALYTIC ENANTIOSELECTIVE HYDROGENATION OF BETA-KETOESTER | |
| US3963585A (en) | Distillation of titanium tetrachloride in solution with selected amines | |
| CN102365254B (en) | Method for producing alcohol compound | |
| DE2110060C3 (en) | Process for the preparation of N-substituted carboxamides | |
| DE69729343T2 (en) | N, N-disubstituted formamides as halogenation catalysts | |
| EP2935091B1 (en) | Method for hydrogenating higher halogen-containing silane compounds | |
| DE2909797A1 (en) | PROCESS FOR THE PRODUCTION OF 2.2'.4.4'.6.6'-HEXANITROSTILBE | |
| US6727384B1 (en) | Method for purifying acid chlorides | |
| DE3104310A1 (en) | METHOD FOR PRODUCING 5-CHLORINE-2-NITROANILINE | |
| WO2014009156A1 (en) | Method for production of allylsilanes from hydrosilanes and allyl chlorides characterized by using a recylable water-insoluble auxiliary base | |
| DE870257C (en) | Process for the preparation of alkylhalosilanes | |
| DE1643075A1 (en) | Process for the preparation of hydrocarbyl oxysilanes | |
| EP0739896A2 (en) | Process for the preparation of 6-oxo-(6H)-dibenz-(c,e)(1,2)-oxaphosphorines | |
| DE1941504A1 (en) | Process for the production of aluminum | |
| DE3540863C1 (en) | Process for preparing hexamethylene diisocyanate | |
| DE2302381A1 (en) | PROCESS FOR THE PRODUCTION OF METHYLENE BRIDGES POLYARYLAMINES |
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 | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20171010 |
|
| WD01 | Invention patent application deemed withdrawn after publication |