DE1092655B - Process for the production of graft polymers - Google Patents

Description

Process for the production of graft polymers graft polymers can can be prepared in a known manner by in a preformed polymer (Primary polymer) generated active sites, which are the starting point for another Polymerization is when you combine the active primary polymer with the grafted Bringing monomers into contact. The active positions can be z. B. by irradiation with high-energy rays such as radium rays, X-rays or Co60 rays, produce. Radiation causes radicals or groups that easily form radicals, z. B. peroxidic groups, generated in the primary polymer, which the graft polymerization initiate.

There are also known processes in which peroxidic groups be introduced into the chain of the primary polymer molecule in another way, e.g. B. by reaction of the primary polymer with air or oxygen, optionally with elevated temperature and under pressure. One can speed up this process by the primary polymer used is polymers or copolymers of monomers, which react particularly easily with oxygen to form peroxide, e.g. B. of p-isopropyl styrene or p-isopropyl-a-methylstyrene, or by adding isopropyl groups by Friedel-Crafts reaction introduces into a polystyrene.

It has now been found that graft polymers are particularly advantageous with valuable properties if one is used to form esters or amides polymer containing capable groups with a upon heating or exposure to light Free radical-forming azo compound or with one easily converted into an azo group by oxidation convertible hydrazo compound, the corresponding to ester or amide formation possesses capable groups, converts them to form ester or amide bonds, the polymer modified in this way, optionally after oxidation of the hydrazo groups mixed to form azo groups with a polymerizable monomer and polymerized the mixture.

Of the known processes for the production of graft polymers, e.g. with the help of peroxide or hydroperoxide groups, the new one differs The method is advantageous in that when the azo groups are introduced into the primary polymer no undesirable changes such as chain breakdown or discoloration occur.

Groups capable of forming esters or amides, hereinafter referred to as functional Groups are e.g.

Carboxylic acid anhydride, carboxylic acid chloride, isocyanate, hydroxyl, Amino, epoxy or imino groups. Among the corresponding functional groups are to be understood as those which are functional with a contained in the polymer Group are able to react with ester or amide formation. Are e.g. in Primary polymer incorporated carboxylic acid groups, the corresponding functional groups e.g. B.

Be hydroxyl, amino, epoxy or isocyanate groups.

Or are the groups in the primary polymer hydroxyl groups, so the corresponding functional groups can e.g. carboxylic acid, carboxylic acid anhydride, Carboxylic acid chloride or isocyanate groups (the urethane group is also in the sense of the invention an ester group).

The primary polymer are polymers of vinyl and vinylidene compounds suitable, e.g. B. Polymers of styrene and its substitution products, of acrylic acid esters, acrylonitrile, methacrylic acid esters, a-chloroacrylic acid esters, Vinyl chloride, vinylidene chloride, vinyl esters, vinyl ethers, vinyl pyrrolidone, isobutylene, Butadiene or isoprene or also copolymers of these compounds with one another or with fumaric acid esters, maleic acid esters, vinyl carbazole or other polymerizable unsaturated compounds.

Leave polymers containing groups capable of forming esters can be easily produced in a known manner, e.g. B. by copolymerization of the above Vinyl or vinylidene compounds with monomers which contain such groups, that is e.g. with acrylic acid, maleic anhydride, acrylic acid chloride, acrylic acid monoglycol esters, Epoxy acrylic acid esters or methacrylic acid esters (e.g. glycidyl methacrylate) or Glycol monovinyl ethers. But also through conversion to already finished polymers such polymers can be produced, e.g. B. hydroxyl-containing polymers by saponifying polyvinyl esters or polyvinyl ester copolymers, or Polymers containing carboxyl groups by saponifying polyacrylic acid esters or of copolymers of fumaric or maleic acid esters.

Polymers that contain functional groups capable of amide formation, can be z. B. by copolymerization of aminoalkylacrylic acid esters, isocyanatoalkylacrylic acid esters or produce isocyanatostyrene.

Azo compounds capable of forming esters or amides and forming free radicals when heated or exposed to light are, for example, azocarboxylic acid derivatives, such as z. B. a, a '-azobis- [a-methyl-y-carboxybutyronitrile], a, a'-azobis-fa-ethyl-y-carboxybutyronitrile], a, a' -azobis- [a, y, y-tri -methyl-γ-carboxybutyronitrile] or R = aliphatic radical, n = 1 to 4, e.g. B. 2- (2'-Hydroxyäthylazo) -2,4-dimethyl-valeronitrile or 2- (2'-Hydroxyäthylazo) -2-ethyl-butyronitrile, which z. By the methods of U.S. Patent Nos. 2,520,338 and 2,778,818.

It is often advantageous instead of having functional groups Azo compound first a corresponding hydrazo compound with the functional React group-bearing polymer and then the polymer thus obtained with Hydrazo groups with chlorine or bromine or other suitable oxidizing agents treat, wherein the hydrazo groups are easily oxidized to azo groups. A corresponding Hydrazo compound, which according to Thiele and Heuser, Ann., 290, p. 1 (1896), especially is easily accessible, e.g.

Hydrazoisobutyric acid: The reaction of the primary polymer with these or similar azo compounds or hydrazo compounds can be carried out in a known manner.

In detail, the reaction conditions depend on those in the primary polymer contained groups. Are in the primary polymer z. B. carboxylic acid chloride groups, so the reaction with an azo compound containing hydroxyl groups already takes place at room temperature.

The same applies if there are isocyanate groups in the primary polymer and in the azo compound, carboxyl or hydroxyl groups. But also with a hydroxyl group containing primary polymer and an azo compound containing carboxyl groups is achieved with the addition of suitable catalytic or dehydrating compounds, such as B. carbodiimides, already at 20 to 30 "C an almost quantitative conversion. These reactions are expediently carried out in a suitable solvent, in which the primary polymer is soluble. If you use azo or hydrazo compounds with more than one group capable of ester or amide formation, then occurs in the course the reaction cross-linking, and a gel is formed. Do you have the esterification or amidation reaction is carried out with hydrazo compounds, the hydrazo groups, before graft polymerization is possible, first into the corresponding azo groups be transferred. This oxidation can easily be carried out in a familiar manner with chlorine or bromine Way to perform by adding to the gel solution of the hydrazo group-containing polymers at 5 to 20 "C a dilute alcoholic bromine solution can be added dropwise until no more discoloration takes place. The solvent used for the polymer is used in this case it is expedient to use ethyl acetate or others against bromine at low temperature inert solvents.

In general it is advantageous to do this with azo groups Primary polymer provided along the chain with a suitable precipitant, such as methanol, water, methanol-water mixtures or hydrocarbons, to precipitate, to wash and, if necessary, to dry.

The amount of azo groups built into the primary polymer can be varied widely.

It depends entirely on the structure of the graft polymer. In extreme cases, for example, a side chain can be grafted onto each primary polymer macromolecule.

In the other extreme case, each monomer unit of the primary polymer can be provided with a side chain.

In the first case, one needs per polymer molecule of the primary polymer a functional group and accordingly on average 1 mole of the corresponding Group-bearing azo or hydrazo compound.

In the second case, one needs per monomer unit of the primary polymer molecule a functional group.

There are as many as you want between these two extreme possibilities Variants in which an average of every second, third, tenth, hundredth etc. Monomer unit of the primary polymer 1 mol of the azo compound or hydrazo compound comes. It is not necessary to be attached to each of these by ester or amide bonds azo groups attached to the primary chain in the subsequent grafting Side chain grows. Some of the azo groups can also be used by recombination Connection of two primary polymer molecules lead or can remain undecomposed and only later, when no more monomer is available, are decomposed, z. B. when processing to moldings.

In practice one can see the concentration of the azo groups along the chain regulate 1. by the concentration of in the molecular chain of the primary polymer functional groups introduced as described, ie z. B. through the relationship Acrylic acid butyl ester to glycol monoacrylate, if the primary polymer has a hydroxyl group containing polyacrylic acid butyl ester, 2. by having the functional groups containing primary polymer converted amount of azo or

Hydrazo compound that has the corresponding functional groups wearing. The azo or hydrazo compound can be used precisely in the stoichiometric ratio can be used, but it can also be an excess or deficiency compared to that in the primary polymer existing groups are applied.

Of particular interest are those graft polymers in which the ratio of moles of monomer residues without functional ones present in the primary polymer Groups Moles of monomer residues with functional groups between 100: 1 and 1: 1, preferably between 25: 1 and 3: 1, and in which the azo compound is in an amount with the primary polymer is implemented, which is approximately the stoichiometric ratio is equivalent to.

However, in special cases, a larger excess or A deficit of the azo compound may be useful, a deficiency, for example, if you wants to avoid precipitating and washing the primary polymer.

To prepare the graft polymers, the azo group-containing Primary polymer dissolved in a suitable monomer. The solution is known in Polymerized manner, e.g. by heating to 40 to 1000 C, preferably to 50 to 800 C, or by exposure to UV rays at 0 to 60 "C, preferably 10 up to 40 "C, with the azo groups decomposing into radicals with elimination of nitrogen, which then trigger the polymerization of the monomer onto the chain of the primary polymer.

Vinyl or vinylidene compounds are suitable as graft monomers, for example styrene or its substitution products, acrylonitrile or methacrylonitrile, Acrylic or methacrylic acid esters or vinyl carbazole, vinyl halides, vinyl lactams, such as vinyl pyrrolidone or butadiene, isoprene, and mixtures of these compounds with each other or with other polymer sable connections, e.g. B. with vinyl ethers, Isobutylene or with maleic or fumaric acid esters.

The type of monomers used for grafting depends on the later intended use of the graft polymers. So you can z. B. on water-insoluble Primary polymers, which are mainly composed of styrene or acrylic acid esters, Grafting on monomers which, when polymerized on their own, yield water-soluble polymers, such as vinyl pyrrolidone, or vice versa. The use is of particular importance of hard and brittle primary polymers, e.g. of compounds containing azo groups modified polymethacrylic acid methyl ester, polystyrene or polyvinyl chloride and of such graft monomers, the softer or rubber-elastic polymers supply, such as methyl, ethyl or ethylhexyl acrylate, butadiene or isoprene. Even more important is the reverse case, namely the use of rubber elastic, preferably saturated, rubber-elastic primary polymers, such as those containing azo groups Compounds modified polyacrylic acid esters, and the grafting of monomers, which form hard homopolymers, such as styrene, vinyl chloride and methyl methacrylate or methyl α-chloroacrylate. In this way one obtains mechanically special high quality transparent graft polymers. The amount of rubber elastic, Primary polymer containing azo groups is expediently 5 to in this case 500/0, preferably 10 to 300 / o, of the total graft polymer. The amount of functional groups in the primary polymer and the amount of azo compound one expediently so that in each case from 2 to 50, preferably from 4 to 20, monomer residues an azo group of the primary polymer is omitted.

In general one can (with a fixed concentration of the azo groups) by the quantitative ratio of primary polymer to graft monomers the length of the Affect the side chains to be grafted on. If you take a lot of primary polymer and little monomer, e.g. in a ratio of 80:20, a graft polymer is obtained with relatively short side chains. In the opposite case, for example with one Primary polymer ratio 20 monomer - 80 ar obtained (with the same azo group concentration) comparatively much longer side chains.

When the primary polymer is crosslinked, e.g. by using The primary polymer is azo compounds which contain more than one functional group Not soluble in the monomers, but only swellable.

In this case, the graft polymerization is special easy, since you can easily crumble the swollen jelly in many cases and the Can suspend gelatinous crumbs in water. The polymerization then proceeds as suspension polymerization without the need to add a protective colloid. The polymerization temperature is expediently 10 to 120 ° C., preferably 50 to 80 "C. Depending on the type of azo compound used and depending on the temperature the polymerization can take 5 to 60 hours.

The graft polymers prepared according to the invention can be utilize technically in various ways, e.g. B. for the production of plastic consumer goods by processing in the injection molding process, in the vacuum deep drawing process, in extrusion or extruders. They can also be used as emulsifiers, protective colloids, thickeners or abrasion-resistant rubbers can be used.

The parts mentioned in the examples are parts by weight.

Example 1 90 parts of butyl acrylate and 10 parts of butanediol monoacrylate are in 100 parts of acetone after the addition of 0.1 part of azodiisobutyronitrile 1 Polymerized under nitrogen at 60 ° C. for an hour in the order given, 500 parts of acetone, 10 parts of a, a'-azo-bis- [a-methyl-y-carboxybutyronitrile], Added 10 parts of diisopropylcarbodiimide and 2.5 parts of pyridine. The temperature of the The solution is kept at 400.degree. After 3 hours, the resulting gel is washed with water and methanol washed in a kneader and then dried in vacuo at 35 ° C. 20 parts of the rubber-like product obtained are mixed with 80 parts of styrene. The styrene is completely absorbed and a crumbly jelly is formed. This is crumbled, suspended in 300 parts of water and stirred under a nitrogen atmosphere Heated for 24 hours at 70 ° C. A hard, tough, transparent graft polymer is obtained. Mixtures of butyl polyacrylate and polystyrene and polymerized solutions Butyl acrylate without azo groups in styrene are opaque white and have only a low mechanical strength.

Example 2 90 parts of ethylhexyl acrylate and 10 parts of butanediol monoacrylic acid ester are dissolved in 100 parts of methyl acetate and, after the addition of 0.1 part of azodiisobutyronitrile and 0.02 part of dodecyl mercaptan polymerized under nitrogen. The solution will be diluted with 100 parts of tetrahydrofuran and with a solution of 9.5 parts of hydrazoisobutyric acid 10 parts of diisopropylcarbodiimide and 2 parts of pyridine are mixed in 50 parts of water. After standing at 25 ° C. for 12 hours, the resulting gel-like mixture becomes at 20 ° C slowly in a kneader with a solution of 7.4 g of bromine in 100 parts of methanol offset. The polymer is then precipitated by adding 2000 parts of methanol and washed repeatedly in the same amount of methanol until no bromide in the Washing liquid is more detectable. It is then added with 1000 parts of methanol stirred into a fine suspension. After adding 112 parts of acrylonitrile, 288 Parts of styrene and 2 parts of polyvinylpyrrolidone (k value 80 according to Fikentscher) the mixture was heated to 700 ° C. under nitrogen for 16 hours. In the course of the polymerization the graft polymer precipitates out in granular form. It is filtered off and dried and left by the methods customary for thermoplastics to form transparent moldings process high impact and notched impact strength.

Example 3 As described in Example 1, a copolymer is used made from butyl acrylate and butanediol monoacrylate and with a, a'-azo-bis- [a-methyl-y-carboxybutyronitrile] implemented. 20 parts of the rubber-like product obtained are mixed with 80 parts Methacrylic acid nitrile mixed, suspended in water and polymerized at 700 C for 24 hours.

A yellow-colored, clear, transparent graft polymer is obtained. A mixture of butyl polyacrylate and polymethacrylic acid nitrile is against it opaque white.

Example 4 80 parts of butyl acrylate and 20 parts of acrylic acid are in 100 parts of acetone after the addition of 0.1 parts Azodiisobutyric acid nitrile copolymerized. The solution is made up of 20 parts in the following order 2- (2'-Hydroxyethyl-azo) -2,4-dimethylvaleronitrile, 20 parts of diisopropylcarbodiimide and 5 parts of pyridine are added and the temperature is kept at 400.degree. After 3 hours the product obtained is washed with water and methanol in a kneader and then dried.

20 parts of the product obtained are in a stirred autoclave with 80 parts of vinyl chloride and 100 parts of butyrolactone mixed and 48 hours at 35 ° C held. An almost transparent graft polymer is obtained, which after addition 1 part of dibutyltin laurate can be rolled into a skin as a stabilizer.

Example 5 10 parts of a copolymer of isobutylene and ethylene glycol monovinyl ether in the ratio 95: 5, in the usual way by low-temperature polymerization with Boron trifluoride produced in liquid ethylene is dissolved in 40 parts of cyclohexane and with 0.8 part of a, a'-azo-bis- [a-methyl-y-carboxybutyronitrile, 1 part of diisopropylcarbodiimide and 0.2 parts of pyridine are added and the mixture is kept at 400 ° C. for 3 hours. The resulting The jelly is washed repeatedly with methanol in a kneader and dried in vacuo. The polymer obtained in this way is mixed with 90 parts of a mixture of 50 parts of cyclohexyl acrylic acid ester and 50 parts of acrylonitrile and 100 parts of butyrolactone intimately mixed and 24 Maintained at 55 ° C under nitrogen for hours.

After distilling off the solvent in vacuo, a light yellow colored, transparent graft polymer.

Example 6 60 parts of butadiene, 30 parts of dibutyl fumarate, 10 Parts of butanediol monoacrylic acid ester, 200 parts of completely demineralized water, 1 part of the Sodium salt of phthalic acid monooleyl ester, 0.2 parts of potassium persulfate and 0.2 Parts of sodium tripolyphosphate are placed in a stirred autoclave at 45 ° C. for 36 hours Nitrogen polymerizes. The polymer dispersion is poured into methanol precipitated and washed repeatedly with methanol. The polymer is in a vacuum 500 ° C., dissolved in 200 parts of benzene and treated with 10 parts of a, a'-azo-bis-la-methyl-y-carboxybutyroni , 10 parts of diisopropylcarbodiimide and 2 parts of pyridine mixed. After 3 hours Standing at 40 ° C, the gelatinous reaction product is thoroughly in a kneader washed with methanol and dried. 25 parts of the so obtained containing azo groups The polymer is mixed with 75 parts of methyl methacrylate and 100 parts of benzene mixed and polymerized at 60 ° C under nitrogen for 24 hours. There arises a clear, transparent, hard and tough graft polymer.

Example 7 90 parts of methyl methacrylate and 10 parts of isocyanatoethyl methacrylate are in 100 parts of acetone with the addition of 0.1 part of azodiisobutyronitrile and 0.05 part of dodecyl mercaptan polymerized under nitrogen at about 600 ° C. for 6 hours. The solution is mixed with 7 parts of a, a'-azo-bis-7a-methyl-y-carboxybutyronitrile] and 1 Part of pyridine mixed. After 48 hours of standing at 25 ° C, the viscous gel solution becomes washed repeatedly with methanol in a kneader.

The hard polymer obtained is dried at 35 ° C. in vacuo. 40 parts of it are intimately mixed with 60 parts of styrene. The result is a crumbly one Gel that is suspended in 300 parts of water and taken at 60 ° C nitrogen is polymerized. A transparent, hard graft polymer is obtained.

Example 8 60 parts of vinylidene chloride, 25 parts of butyl acrylate and 15 parts of isocyanatoethyl methacrylic acid ester are in a mixture of the same Parts of methyl ethyl ketone and methyl acetate with the addition of 0.1 part of azodiisobutyronitrile polymerized under nitrogen. The solution is mixed with 13.6 parts of a, a'-azobis- [a-methyl-y-carboxybutyronitrile] and 1 part pyridine mixed. After 48 hours of standing at 25 ° C, the viscous Gel solution washed repeatedly with methanol in a kneader. The polymer obtained is dried in vacuo at 300.degree. 20 parts of it are mixed with 80 parts of a mixture from 65 parts of methyl methacrylate and 35 parts of acrylonitrile and with 100 Parts of y-butyrolactone mixed. The mixture is kept under nitrogen for 24 hours 55 "C polymerized.

The resulting graft polymer becomes after the addition of 1 part of dibutyltin laurate freed from butyrolactone as a stabilizer in vacuo and heated at 1400 ° C. for 5 minutes treated by a rolling mill. It can be pressed into transparent sheets.

Example 9 85 parts of ethylhexyl acrylate and 15 parts of acrylic acid are in 100 parts of acetone after the addition of 0.1 part of azodiisobutyronitrile and Polymerized 0.05 part of dodecyl mercaptan under nitrogen at about 600 ° C. for 6 hours. The viscous solution is with 15 parts of a, a'-azo-bis- [a-methyl-y-carboxybutyronitrile], 16 parts of diisopropylcarbodiimide and 1 part of pyridine mixed and 12 hours at Maintained 25 ° C. The gel-like mixture is introduced into 2000 parts of methanol and Washed carefully with methanol and then dried at 300 ° C. in vacuo. 75 parts of the rubber-elastic polymer produced in this way are mixed with 25 parts one consisting of equal parts of methyl methacrylate and acrylonitrile Mixture mixed homogeneously in a kneader and polymerized at 700 C under nitrogen. A slightly crosslinked, tough rubber-like graft polymer is obtained, which by Incorporation of diisocyanates can be crosslinked even more strongly.

Claims (1)

PATENT CLAIM Process for the production of graft polymers, thereby characterized in that one contains a group capable of forming esters or amides Primary polymer with an azo compound which forms free radicals when heated or exposed to light or with a hydrazo compound which can easily be converted into an azo compound by oxidation, which contains the corresponding groups capable of ester or amide formation, with the formation of ester or amide bonds in a known manner and that Primary polymer modified in this way, optionally after oxidation of the hydrazo groups to azo groups, mixed with a polymerizable monomer and polymerized the mixture.