DE1231899B - Process for the production of graft polymers - Google Patents

Description

Process for the preparation of graft polymers It is known that Graft polymers e.g. B. be produced in that in high polymer compounds Radical or slightly radical-forming groups are introduced, e.g. B. by irradiation or by peroxidation, which then takes place under the polymerization conditions in the presence of a monomer which trigger graft polymerization. But there is a very fundamental one The disadvantage of this method is that in addition to the graft polymers, there are always homopolymers of the added monomer arise. The molar fraction of homopolymer versus the graft polymer depends on the polymerization activity of the various occurring Radicals as well as the transfer constant of the growing macroradical with his Monomers and the solvent. Also occur in the graft polymerization according to a radical mechanism, often cross-links which have the consequence that the graft polymers become insoluble and therefore not for many applications are more suitable.

It is also known that metal amides, also N-substituted and N, N-disubstituted, of metals of main groups I and II of the periodic table stimulate the anionic polymerization of vinyl monomers, being in hydrocarbons as a polymerization medium, preferably sterically uniform, e.g. B. isotactic or syndiotactic polymers arise.

There has now been a process for the preparation of graft polymers by anionic polymerization of monomers to high molecular weight reaction products between Nitrogen-containing polymers and organometallic compounds of I. or II. Main group or the II. Subgroup of the Periodic table found that by is characterized in that one has high molecular weight silicon-containing N-substituted metal amides or metal imides, which are formed by the addition of silicon-substituted organometallic Compounds of main group I or II or subgroup II of the periodic table to macromolecules containing nitrile or pyridine groups at 100 to +200 "C and pressures up to 200 atm have been produced with anionically polymerizable monomers at -100 to +200 "C and pressures up to 200 atm, preferably in inert solvents and reacted under an inert atmosphere.

The organometallic compounds of metals of the I. and II. Main or II. Subgroups of the periodic table add to the carbon-nitrogen multiple bonds of the nitrile group-containing or pyridine group-containing polymers to form N-substituted metal amide or. Metal imide groups that are connected to the polymer via major valence formations.

The anionically polymerizable monomers can optionally in a preferably stereospecific arrangement on the "backbone" polymer grow up, creating graft polymers, whose side branches one preferably have an isotactic or syndiotactic arrangement.

Suitable as polymers containing nitrile groups or pyridine groups polymers which contain nitrile and / or pyridine substituents in structural units, such as B. Polymers of acrylonitrile, methacrylonitrile or vinylidenecyanide, and also other ethylenically unsaturated compounds containing nitrile groups, or their copolymers with one another or with ethylenically unsaturated hydrocarbons, such as ethylene, propylene, styrene, a-methylstyrene, vinyltoluenes, a-vinylnaphthalene, or with serving, e.g. B. butadiene, isoprene, dimethylbutadiene, or polymers of vinyl pyridines, z. B. of 2- or SVinylpyridins, or ring-substituted vinylpyridines, such as the Vinyl picolines, or their copolymers with one another or with ethylenically unsaturated Hydrocarbons or dienes, such as those mentioned above, as well as ethylenic unsaturated compounds containing nitrile groups. The mean molecular weights the polymers containing nitrile groups or pyridine groups extend over a range from about 10 4 to about 5 106, but can also according to the invention Polymers containing nitrile or pyridine groups and having a lower or higher molecular weight be used.

Among organometallic compounds of metals containing silicon the I. or II. main group or the II. subgroup are compounds of the metals to understand the I. and II. main group as well as the II. subgroup of the periodic table, in which the metal has at least one major valence bond with a carbon atom an organosilicon compound is connected. So are z. B. silicon-substituted Alkyls, cycloalkyls, aralkyls or aryls of the alkali and alkaline earth metals as well of the metals of the II. subgroup or silicon-substituted alkyl, cycloalkyl, Aralkyl and aryl metal halides of the II. Main or subgroup of the periodic table, z. B. trimethylsilylmethyllithium, trimethylsilylphenylsodium, triphenylsilylmethyllithium as well as corresponding beryllium, magnesium, calcium, cadmium or zinc derivatives, also organosilicon Grignard compounds, such as. B. Trimethylsilylmethylmagnesium halides, Dimethylsilylmethylmagnesium halides, dimethylsilylphenylmagnesium halides, Trimethylsilylbenzylmagnesium halides as well as the corresponding zinc and Cadmium halides.

The reason for the use in accordance with the invention is exclusively silicon-containing organometallic compounds of the I. and II. main group as well as the II. subgroup of the periodic table is that those derived therefrom with nitrile or pyridine groups High molecular weight organometallic addition compounds that can be prepared from polymers soluble even after the addition of many molecules of the organometallic compounds stay. Only in this way does the subsequent grafting reaction have a wide range variable degree of grafting achieved, which for the favorable technical properties of the products is crucial.

In principle, any silicon-free organometallic Compounds of main group I and II or subgroup II of the periodic table store on polymers containing nitrile or pyridine groups. In contrast to the corresponding related In silicon-containing products, however, the polymers become already after the addition of 1 or at most 2 molecules of the organometallic compound per macromolecule insoluble and fall out of solution, eliminating any further attachment of the organometallic compound is completely prevented.

Therefore, silicon-free organometallic compounds are only obtained Macromolecules with one or at most two starting sites per molecule. these can in the graft reaction only products with an extremely low degree of grafting result, which have no technically interesting properties, as from others Examples is known.

Implementation of the organometallic compounds of metals I. or II. Main group or the II. Subgroup with nitrile groups or pyridine groups Polymer is preferably in a solution inert under the reaction conditions or dispersants carried out, for which z. B. aliphatic, cycloaliphatic and aromatic hydrocarbons as well as straight-chain or cyclic ethers are suitable, such as B. pentane, hexane, heptane or higher straight-chain or branched paraffins, Cyclohexane, benzene, toluene, xylenes, tetrahydronaphthalene, decahydronaphthalene or their mixtures with one another, as well as dimethyl ether, diethyl ether, higher straight-chain or branched dialkyl ethers, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, Diethylene glycol diethyl ether, tetrahydrofuran, dioxane, and also mixtures of different Ether with each other or with hydrocarbons. When using low-boiling solvents it is expedient to work under pressure, which is easily up to 200 atm can be increased.

The implementation of silicon-containing organometallic compounds of metals of main group I or II or subgroup II of the periodic table with polymers containing nitrile groups or pyridine groups is found in many Cases take place at very low temperatures or room temperature, but this is required in other cases they have increased reaction temperatures, which, however, reduce the decomposition temperatures of organometallic compounds must not exceed.

All anionically polymerizable monomers are suitable for grafting, z. B. acrylic and methacrylic acid derivatives, such as esters, nitriles, amides, e.g. B. methacrylate, Butyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, as well anionically polymerizable ethylenically unsaturated hydrocarbons, e.g. B. styrene, α-methylstyrene, vinyltoluenes, vinylnaphthalenes, dienes, such as butadiene, isoprene, dimethylbutadiene, Chloroprene, also substituted styrenes, e.g. B. halostyrenes, such as p-chlorostyrene, p-bromostyrene, as well as vinyl pyridines, such as 2- and 4-vinyl pyridine, and their derivatives, such as vinyl picolines, also N-vinyl heterocycles, e.g. B. N-vinylcarbazole, as well as cyclic ones Lactones and cyclopolysiloxanes.

The anionically polymerizable monomers are usually at temperatures between -100 and + 200-C the adduct of nitrile groups or pyridine groups Polymers and organometallic compounds containing silicon from metals of the I. or II. Main or II. Subgroup of the periodic table added, namely either in substance or with one under the reaction conditions inert solvent diluted. Mixtures of two or more monomers can also be used be added, depending on the electroaffinity of the anionically polymerizable Monomeric graft polymers are formed, the side branches of which are copolymers or Represent block polymers. When using low-boiling monomers, the inventive Implementation can also be carried out with the application of pressure, without any harm up can be increased to 200 atm.

Since both the silicon-containing organometallic compounds of Metals of main group I or II or subgroup II of the periodic table and their addition compounds to those containing nitrile groups or pyridine groups Polymers as well as those occurring during anionic graft polymerization polymeric carbanions of water, alcohols or other proton donors and oxygen are destroyed, it is usually essential, the reactions only in dry solvents or dispersants and to be carried out under inert protective gases. As protective gases In addition to all noble gases, nitrogen and hydrogen are particularly suitable.

In many cases, the anionic reactions occur in the course of the graft polymerization polymerizable monomers to considerable heat of polymerization, which by a suitable external cooling of the reaction vessel or by an inert diluent can be removed from the corresponding boiling point.

During the course of the graft polymerization, the amount added to the reaction mixture Monomers, it is often advantageous to keep the reaction mixture in motion in order to achieve a to achieve good mixing of the reaction components.

The polymerization of the anionically polymerizable monomers occurs to its end when all of the monomers present in the reaction mixture have been consumed. But it can be stopped before this point in time, e.g. B. by adding chain-breaking substances such as water, alcohols, acids, amines and others Proton donors.

The graft polymers produced by the process according to the invention have depending on the choice of the starting polymers, the grafted monomers and the The number and length of the grafted-on sides make a multitude of technically interesting ones and new features. Particularly interesting are those products where either the main chains or the grafted side branches an internal softening of the Cause graft polymers.

The process of the invention is illustrated by the examples below illustrated. Parts by weight and parts by volume are in the same ratio to one another like grams and milliliters.

Example 1 11 parts by weight of a copolymer of styrene and acrylonitrile with an average molar composition of 4.6 molecules of styrene per molecule Acrylonitrile in the copolymer and an average molecular weight of about 1.8 105 are dissolved in 500 parts by volume of tetrahydrofuran and 10 parts by volume of a 1.8 molar Solution of trimethylsilylmethylmagnesium chloride in ether under rapid Stir and Nitrogen was slowly added, the solution turning light green. After cooling down at 0 ° C., 50 parts by volume of acrylonitrile are added with rapid stirring, with the reaction mixture immediately turns dark yellow. After stirring at 0 ° C. for 5 hours, the mixture becomes the polymer precipitated in methanol and dried in vacuo. You get 22 weight parts light yellow graft polymer, which is dissolved in benzene, a solvent for the starting polymer, only swells, but dissolves in dimethylformamide.

Its IR spectrum shows the presence of polymeric acrylonitrile besides the characteristic bands of the starting copolymer. - The implementation proceeds in the same way, if, instead of trimethylsilylmethylmagnesium chloride, trimethylsilylmethylmagnesium iodide used.

Example 2 10 parts by weight of a styrene-4-vinylpyridine copolymer the molar composition of 5.3 molecules of styrene per molecule of 4-vinylpyridine in copolymer and an average molecular weight of about 8.8 104 are in 300 Parts by volume of tetrahydrofuran dissolved and 14 parts by volume of a molar solution of trimethylsilylmethyllithium in ether was added dropwise with rapid stirring, the solution turning green-yellow. To this end, 20 parts by volume of acrylonitrile are added with stirring at 20 "C. The reaction mixture was stirred at this temperature for 20 minutes, then precipitated in methanol. 15 parts by weight of a yellow graft polymer are obtained, which is dissolved in hot toluene, a solvent for the starting polymer, only swells, but turns into dimethylformamide dissolves.

Its IR spectrum shows the characteristic bands of the backbone polymer and the side branches.

Example 3 For the solution of 5 parts by weight of styrene-acrylonitrile copolymer (see Example 1) in 80 parts by volume of tetrahydrofuran are flushed with nitrogen and stirring at room temperature 6 parts by volume of a 1.48 molar solution of dimethylsilylmethylmagnesium chloride added dropwise in tetrahydrofuran, the mixture turning light green. After 30 minutes Stirring at reflux temperature, it is cooled to 30 ° C. and 20 parts by volume of 4-vinylpyridine admitted. The solution turns lemon yellow, its viscosity increases rapidly, and within 25 minutes it solidifies to a clear, gelatinous mass. By stirring with 5 parts by volume of ethanol, the polymerization is terminated and the polymer dissolved in 100 parts by volume of dimethylformamide. After precipitation in water and drying 14.18 parts by weight of rubber-elastic, colorless graft polymer are obtained in vacuo. - The reaction proceeds analogously if one takes the place of dimethylsilylmethylmagnesium chloride the trimethylsilylmethylmagnesium chloride is used.

Example 4 For the solution of 5 parts by weight of styrene-acrylonitrile copolymer (cf. Example 1) in 80 parts by volume of tetrahydrofuran are added with stirring and under a nitrogen atmosphere at 20 ° C 6 parts by volume of a 1.48 molar solution of dimethylsilylmethylmagnesium chloride added dropwise in tetrahydrofuran, the solution turning light green. She turns 30 Minutes heated to reflux, cooled to - 60 C and under rapid Stirring 20 parts by volume of acrylonitrile added. The solution turns light yellow after 10 minutes there is an increasing cloudiness, accompanied by an increase in viscosity, and after 1 hour the reaction mass has solidified like a gel. By adding 3 parts by volume Water, the polymerization is terminated and the polymer in 40 parts by volume Dissolved dimethylformamide. Obtained after precipitation in methanol and drying in vacuo one 12.60 parts by weight of graft polymer as a light yellow powder in warm toluene swells and is soluble in dimethylformamide. - The implementation is analogous if instead of dimethylsilylmethylmagnesium chloride, p-dimethylsilylphenylmagnesium chloride is used used.

Claims (1)

Claim: Process for the production of graft polymers by anionic polymerization of monomers on high molecular weight reaction products between Nitrogen-containing polymers and organometallic compounds of I. or II. Main group or the II. Subgroup of the periodic table, thereby gekennze.chn e t that one can use high molecular weight silicon-containing N-substituted metal amides or metal imides, the addition of silicon-substituted organometallic compounds of the I. or II. Main group or the II. Subgroup of the periodic table of nitrile or macromolecules containing pyridine groups at -100 to + 200 ° C and pressures up to 200 atm, with anionically polymerizable monomers at - 100 to + 200cC and pressures up to 200 atm, preferably in inert solvents and reacted under an inert atmosphere. Publications considered: Documentation laid out by the Belgian Patent No. 585,104.