DE2841713A1 - METHOD FOR PRODUCING POLYFUNCTIONAL ISOCYANATES FROM POLYMERIC N-HALOGENAMIDES - Google Patents

Description

Process for the production of polyfunctional

Isocyanates from polymeric N-haloamides The present invention relates to a process for the preparation of polymeric isocyanates from polymeric N-haloamides based on acrylic and methacrylamide.

From US-PS 39 29 744 (cf. also H. 1. Wright and K.E. Harwell in Journal of Applied Polymer Science, Vol. 70 (1976), pages 3305-3311) is known, that polymers containing amic groups with excess aqueous alkali metal hypochlorite in Presence of an inert solvent at temperatures ranging from 0 to 15 0C can be converted to isocyanates. The disadvantage of this process is that the reaction can be carried out in a mixture of organic solvents and water must perform. It cannot be avoided that part of the isocyanate formed is hydrolytically decomposed during the work-up of the reaction mixture. Above the stage of the unstable carbamic acid, the corresponding - undesirable - Amines in a known manner according to Hofmann. These amines react with what has not yet been decomposed Isocyanate to ureas, that means a further loss of yield. E.g. according to Example 15 of the US patent in the implementation of an amide group-containing Polymers with sodium hypochlorite initially 5.2 wt. B isocyanate present, after the Isolation of the isocyanate by removing the water by azeotropic distillation however, only 3.25% by weight of isocyanate groups can be detected. Also by adding Emulsion breakers to the aqueous-organic reaction mixture can no complete separation of the aqueous and the isocyanate-containing organic Phase to be reached. A loss of isocyanate yield must also be taken into account here be taken. The long ones are also disadvantageous with this work-up method Segregation times, which in the best case require at least several hours, however, it can also be several days.

The present invention relates to a method of production of polyfunctional isocyanate derivatives of homo- or copolymers of acrylamide or methacrylamide, which is characterized in that a corresponding N-chloramide derivative is used of the homo- or copolymer of acrylamide or methacrylamide with a tertiary Amine with a pKa value greater than 7 in the presence of an inert solvent and at temperatures in the range from 20 to 1800C.

The N-chloramide derivatives required in the process according to the invention are obtained by chlorination of the corresponding polymers containing amide groups.

Suitable polymers containing amide groups> some of which are already in the US-PS 39 29 744 are described are the following: polyacrylamide, polymethacrylamide, Copolymers of methacrylamide or acrylamide and styrene, methyl styrene, dimethyl styrene, p-chlorostyrene, o-chlorostyrene and alkyl acrylates such as methyl acrylate, methyl methacrylate, Ethyl acrylate, ethyl methacrylate, butyl acrylate, hexyl acrylate, decyl acrylate and dodecyl acrylate as well as by means of common crosslinking agents such as divinylbenzene and divinyl ether crosslinked products of the polymers and copolymers mentioned.

The homo- and copolymers used contain 5 to 100 mol% acrylic or methacrylamide. The molecular weight distribution of the homo- and Copolymers widely distributed.

The average molecular weight can vary from 1000 to 10,000, polymers with an average molecular weight of 5000 to 10 are preferred 000 used. The crosslinked starting polymers can, for example, with 1 to 10 mole percent of a divinyl compound be crosslinked.

The chlorination of the amide group-containing homo- and copolymers is preferably by means of chlorine in an aqueous mineral acid suspension at temperatures of 0 to 400C. Dilute aqueous mineral acids, for example, are suitable as aqueous mineral acids Hydrochloric acid, sulfuric acid and phosphoric acid. It is preferable to start with one neutral aqueous suspension of the amide-containing polymers, whereby the hydrogen chloride formed as a by-product in the chlorination in the reaction mixture dissolves and the reaction thus takes place in a dilute aqueous hydrochloric acid medium. Preferred is also used by dilute hydrochloric acid or dilute sulfuric acid aqueous suspensions the amide group-containing polymers assumed. The chlorination is exothermic and is preferably carried out at temperatures from 0 to 30 ° C. The application Temperatures higher than 40 ° C. are disadvantageous because they are noticeable due to hydrolysis Amounts of carboxyl groups are formed. The chlorination can be both at normal pressure can also be carried out under increased pressure. As the pressure increases, the reaction time, but the preferred pressure range is economical Reasons between 1 and 6 ata. Since the chlorination takes place in a heterogeneous phase, ensure that the suspension is well mixed. The dilution of the reaction mixture should at least be so dimensioned that the same stirs without difficulty or can be mixed in other ways.

The preferred dilution of the reaction mixture is approx. 100 to 200 g of polymer containing amide groups per liter of water or aqueous mineral acid. If the process conditions mentioned are observed, the chlorination is after about Completed 0.25 to 2 hours. Depending on the composition of the amide groups Polymers turn about 30 to 95% of the amide groups into N-chloramide groups under these conditions convicted. The suspension present after the chlorination is complete contains as Solid only the modified polymer. This can be done in the simplest possible way separated by filtration or centrifugation.

Is essential for the success of the method according to the invention the selection of an appropriate base is critically important. According to the invention tertiary amines with a certain basicity are used. As a measure of the basicity is given as the basicity constant PKa. For the inventive Process suitable tertiary amines must have a minimum basicity, which corresponds to a pKa value of more than 7. Suitable tertiary amines are aliphatic, cycloaliphatic and aromatic amines such as (in brackets the associated pKa values at 250 ° C.): trimethylamine (9.80), triethylamine (10.74), tri-n-butylamine (9.89), 2.4.6-trimethylpyridine (7.45-7.63), tri-n-propylamine (10.74), ethyldimethylamine (10.06), propyldimethylamine (10.16), isopropyldimethylamine (10.38), methyldimethylamine (10.43), butyldimethylamine (10.31), 2.3.4 * 5-tetramethylpyridine (7.78) and 2.3.4.5.6-pentamethylpyridine (8.75).

Preferred tertiary amines are trimethylamine, triethylamine and tri-n-propylamine and tri-n-butylamine. The pRa values can be found in the usual manuals. In the case of aliphatic tertiary amines, in particular, reference is made to L. Spialter et al., The Acyclic Aliphatic Tertiary Amines, The McMillan Campany, New York (1965) and in the case of substituted pyridines on Rlingsberg, heterocyclic compounds pyridines and Derivates, Part 2, Interscience Publishers Inc., New York (1961).

The basicity of the tertiary amine used is essential for the course the reaction is significant, and that is when using polymers with the same N-chloramide content the lower the pK value of the tertiary amine, the lower the isocyanate yield is.

The tertiary amine is used in at least one molar equivalent used per ol N-chloramide content in the polymer.

The preferred equivalence ratio of N-chloramide content to tert. Amine is 1: 1 to 1: 4. Larger amounts of tertiary amine can be used without prejudice but should be avoided for economic reasons.

When choosing the organic solvent, make sure that that this under the reaction conditions neither with the N-chloramide group nor may react with the isocyanate group or the tertiary amine used. Suitable solvents are, for example: methylene chloride, 1,1-dichloroethylene, Chloroform, carbon tetrachloride, trichlorethylene, tetrachlorethylene, pentane, hexane, Cyclohexane, heptane, octane, benzene, toluene, ethylbenzene, chlorobenzene, xylene, dichlorobenzene, Diethyl ether, tetrahydrofuran, dioxane, methyl acetate, butyl acetate and methyl propionate. The solvents toluene, xylene, chlorobenzene, Butyl acetate, chloroform, tetrachlorethylene, carbon tetrachloride, cyclohexane and dioxane The preferred dilution of the reaction batches is approx.

100 to 200 g N-chloramide-containing polymer per liter of solvent, however, lower and higher concentrations can be used.

The reaction temperatures are in the process according to the invention Range from 20 to 1800C. They essentially depend on the type of used Polymers, their N-chloramide content and the basicity of the tertiary Amines. With some starting materials, the reaction starts at room temperature and sometimes even very violently. Usually the reaction takes place at the boiling point carried out of the solvent used in each case. The preferred reaction temperatures are in the range from 65 to 1350C.

The reaction times required are in the process according to the invention in short, they usually last a few minutes.

However, without prejudice to longer reaction times, for example a response time of one hour should be applied.

To carry out the method according to the invention, it is expedient the N-chloramide-containing polymer is dispersed in the solvent and then with the required Minimum amount of tertiary amine added. In some cases, the response continues immediately one, in other cases, is rapidly reached the desired reaction temperature in which Usually the boiling point of the solvent used, heated if necessary further heated under reflux for a long time and after conversion and cooling has taken place the resulting hydrochloride of the tertiary amine was separated off from the reaction mixture and finally the filtrate concentrated in vacuo.

Of course, the isocyanate-containing filtrate can also be used directly for Reactions such as those used with compounds containing hydroxyl groups will.

Example 1: 10 g of a copolymer of 10 parts of methacrylamide, 50 Parts of methyl methacrylate and 40 parts of butyl acrylate were in 100 g of 5% hydrochloric acid dispersed. This was followed by 4 hours at 15 to 200C Chlorine passed through. After stripping off the excess chlorine with nitrogen the polymeric N-chloramide was filtered off with suction and washed neutral with distilled water and dried at 350C in a vacuum (30 mbar).

There were 10.2 g of polymeric N-chloramide with an active chlorine content of 3.1% isolated, i.e. 69% of the amide groups of the polymer are in the chloramide been convicted.

Example 2: 10 g of a copolymer of 20 parts of methacrylamide, 40 Parts of methyl methacrylate and 40 parts of butyl acrylate were dissolved in 100 g of 5% strength hydrochloric acid chlorinated with a chlorine pressure of 4 bar at 200C for 30 minutes. The isolation of the N-chloramide was carried out as indicated in Example 1. There were 10.35 g of polymer N-chloramide obtained with an active chlorine content of 6.4%, i.e.

47% of the amide groups have been chlorinated.

Example 3: 10 g of polymeric N-haloamide, represented by chlorination of a copolymer of 10 parts of methacrylamide, 50 parts of methyl methacrylate and 40 parts Parts of butyl acrylate with an active chlorine content of 3.1% were dissolved in 1CO ml of toluene suspended.

After the addition of 3 g of triethylamine, the mixture rapidly increased Heated to 100 ° C and left at this temperature for 30 minutes. After that there were excess Triethylamine and 20 ml of toluene are distilled off. The precipitated triethylamine hydrochloride and other undissolved portions were separated after cooling and the filtrate concentrated in vacuo. 9.5 g of resin remained with an isocyanate content of 3.4 %.

Example 4: Example 2 was carried out analogously to Example 1, only the same amounts of chlorobenzene and dioxane were used instead of toluene and butyl acetate used. The isolated amounts are from Table 1 on polymeric isocyanate and their NCO content can be seen.

Table 1 Reaction medium weight of polymeric NCO content (%) isocyanate Chlorobenzene 9.3 g 3.35 dioxane 9.5 g 3.2 butyl acetate 9.25 g 3.5 Example 5: 10 g of polymeric N-haloamide, prepared by chlorination of a copolymer from 20 parts of methacrylamide, 40 parts of methyl methacrylate and 40 parts of butyl acrylate with an active chlorine content of 6.4% were as in Example 3 in toluene under Addition of 5 g of triethylamine converted into the polymeric isocyanate. It was 9.25 g of a resin with an NCO content of 4.7 e was obtained.

Example 6: Other polymeric N-chloramides were - as in the preceding Examples described - in toluene with triethylamine to the polymeric isocyanates implemented.

Table 2 shows the composition of the polymers and the chlorine content of the polymeric N-halogenamides, as well as the NCO content of the resulting polymers Isocyanates can be seen. Table 2 Polymer Composition Chlorine Content converted triethyl weight NCO content amount amine N-chloramide g% 10% methacrylamide 3 10 2 9.6 3.2 90% decyl acrylate 30% methacrylamide 10.1 10 10 8.8 5.5 30% methyl methacrylate 40% butyl acrylate 30% methacrylamide 11.2 10 10 8.6 5.6 70% butyl acrylate example 7: 10 g of polymeric N-haloamide, prepared by chlorination of a copolymer from 20 parts of acrylamide and 80 parts of methyl methacrylate with an active chlorine content of 7.7% were as in Example 1 in toluene with the addition of 5 g of triethylamine converted into the polymeric isocyanate.

4.8 g of polyisocyanate with an NCO content of 4.7 * were isolated.

Example 8: 10 g of polymeric N-haloamide of the type indicated in Example 3 Composition were suspended in 50 ml of toluene and a solution of 3 g of trimethylamine added in 50 ml of toluene. The mixture was quickly brought to reflux temperature (1100C) heated.

Excess trimethylamine escaped in gaseous form during the heating process. It was boiled for 1 hour, then cooled, trimethylamine hydrochloride suctioned off and the filtrate concentrated in vacuo. 9.3 g of resin were used as residue obtained an NCO content of 4.5%.

Example 9 10 grams of polymeric crosslinked N-haloamide represented by Chlorination of a 5 * divinylbenzene crosslinked polymethacrylamide with a Active chlorine content of 17% were suspended in 100 ml of toluene and, after the addition of Treated 20 g of triethylamine for 30 minutes at 110.degree. After cooling, it was filtered off with suction and the residue was washed with chloroform to remove the triethylamine hydrochloride. 7.5 g of a white powder with an NCO content of 9.8% remained.

Example 10: A mixture of 10 g of polymeric crosslinked N-haloamide of the composition given in Example 6, 26 g of tripropylamine and 100 ml of chlorobenzene was heated to 1300C for 10 minutes.

It was then filtered off with suction, washed with chlorobenzene and the residue dried. 7.7 g of polymeric crosslinked isocyanate with an NCO content were obtained received by 9.6%.

Claims (5)

Claims: 1. Process for the production of polyfunctional Isocyanate derivatives of homo- or copolymers of acrylamide or methacrylamide, characterized in that a corresponding N-chloramide derivative of the homo- or copolymers of acrylamide or methacrylamide with a tertiary amine with a pKa value of more than 7 in the presence of an inert solvent and at temperatures in the range from 20 to 180 0 converts. 2. The method according to claim 1, characterized in that the solvent aliphatic, cycloaliphatic and aromatic halogenated hydrocarbons, aliphatic, cycloaliphatic and aromatic hydrocarbons, carboxylic acid esters or ethers can be used. 3. The method according to claims 1 and 2, characterized in that that the base trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine or 2.4.6-Trimethylpyridine can be used. 4. The method according to claims 1 to 3, characterized in that that the amount of the tertiary amine is 1 to 4 equivalents based on the N-chloramide content of the polymer. 5. The method according to claims 1 to 4, characterized that the reaction takes place at temperatures from 65 to 13500.