DE947115C - Process for the production of granular polymerization products of methacrylic acid - Google Patents

Description

(WiGBl. P. 175)

ISSUED AUGUST 9, 1956

INTERNAT. CLASS C08f

R 2066 IVb / 39c

have been named as inventors

Röhm & Haas G.m.b.H., Darmstadt

of methacrylic acid

Addendum to Patent 749

(Ges. Of 15.7.1951)

The main patent started on December 8, 1938

Patent application published August 20, 1953

Patent issued July 19, 1956

The subject of patent 749 016 is a process for the production of granular polymethacrylic acid with Aid of polymerization catalysts, which is characterized in that methacrylic acid in an aqueous Electrolyte solution of such a concentration that the monomeric methacrylic acid is essentially undissolved remains, is distributed by mechanical movement and is polymerized in the distributed state.

It has been found that the process can be carried out particularly advantageously if one is not pure Methacrylic acid, but mixtures of at most 80 percent by weight methacrylic acid and at least 20 percent by weight of other polymerizable monomeric ethylene derivatives, which are water-insoluble polymers form, polymerize. Particular mention should be made of such derivatives: methacrylic acid and acrylic acid esters and the corresponding nitriles, also styrene or vinyl chloride. In contrast to the in the main patent already mentioned copolymers of methacrylic acid with subordinate

Amounts of other polymerizable compounds may only be used for the process according to the invention Above proportions are used. The copolymers produced in this way are completely insoluble in water, but easily dissolve in alkalis to form viscous solutions. Particularly copolymers of methacrylic acid and methyl methacrylate are suitable, e.g. B. in the ratio 6o: 40. The advantages of producing these copolymers and the products obtained from them are as follows:

The copolymers are practically no longer swellable in water; you can after manufacture slightly electrolyte-free using the method described in the main patent with pure water can be washed, while pure polymethacrylic acid can only be washed with electrolyte solutions, especially with dilute ones Hydrochloric acid, can be washed. The drying of the washed, powdery copolymers takes place much more quickly and easily than that of pure acids. The viscosity of the copolymer solutions can be largely changed by shifting the ratio of the components. Will be a number made of copolymers with decreasing methacrylic acid content under otherwise identical conditions, so the viscosity of their alkali salt solutions increases sharply.

This increase can be seen from the following summary.

composition Methyl-
methacrylate Viscosity of the io ° / ₀ igen of the copolymer 20th Sodium salt solutions *) Methacrylic acid 30th II seconds 80 40 12th 70 45 15th • 60 50 18th 55 55 40 50 130 45

*) Fall time of a steel ball with a diameter of 2.5 mm for a 20 cm column of liquid at 20 ^° C.

By changing the polymerization conditions, the viscosity can also be increased very widely Change boundaries.

Copolymers with a content of more than 60 ° / ₀ of methyl methacrylate, however, are not to bring in aqueous alkali solutions in solution. The dissolving of the soluble copolymers in aqueous alkali solutions is easier and more convenient than that of pure polymethacrylic acid, since, strangely, they do not stick together when the copolymers are dissolved. A particular advantage of the copolymers produced according to the invention is that they can easily be produced completely odorless, which is of great importance when used in particular in the cosmetic industry. The solutions of the salts of the copolymers are clear as water. - "'

The production of the new copolymers can also be made particularly simple in that

the easily accessible esters of methacrylic acid can be used as starting material, with which there is no need to isolate the technically difficult to access monomeric methacrylic acid.

example 1

200 parts by weight of methyl methacrylate are mixed with 88 parts by weight of caustic soda in 220 parts by weight Saponified water.

60 parts by weight of a methanol-water mixture are distilled off from the reaction mixture. Then, 130 parts by weight of water, in which 2 parts by weight of polyacrylic acid, sodium are dissolved are added and acidified with 226 parts by weight of 45 ° / _o sulfuric acid. It werden- then further 138 parts by weight of methyl methacrylate and 34 parts by weight of acrylonitrile, which contains 0.3 ° / ₀ dibenzoyl peroxide emulsified in the mixture.

With stirring, is heated to 70 ^0th As the polymerization begins, the mixture heats up and is kept at 70 to 72 ° by cooling. The polymerization is complete after 2 hours; the polymer is in the form of fine pearls, is filtered off, washed with water and dried.

A xo ⁰ / ^ ge solution of the sodium salt has a KügelfaUzeit 75 seconds, according to the above method was measured.

Example 2

A copolymer of 60 parts by weight of methacrylic acid and 40 parts by weight of methyl methacrylate is prepared as follows: 314.8 parts by weight of methyl methacrylate are saponified with 300 parts by weight of 26.5% sodium hydroxide solution. A solution of 1 part by weight of sodium polyacrylate and 0.3 part by weight of sodium isopropylnaphthalenesulfonate is then added added in 30 parts by weight of water, acidified with 207 parts by weight of 45% ^r sulfuric acid, added to a slurry of 0.29 parts by weight of dibenzoyl peroxide in ro parts by weight of water and the mixture heated with stirring to 74 °.

The polymerization takes place within 2 hours. After the end of the polymerization, the filter is filtered granular polymer washed with water and dried. .

The io ^e% strength solution of the ammonium salt in water has a falling-ball time of 300 seconds.

Example 3

The procedure is as in Example 2, but instead of the solution of polyacrylic acid sodium 25 parts by weight of talc added. The polymerization tao takes place somewhat more slowly; the polymer forms proportionally .small pearls, which exist in a mixture with talc.

According to the literature, it should be possible to use mixtures of methacrylic acid and other vinyl compounds in aqueous emulsion in granular form

to polymerize. However, reworking of this information shows that according to the known method owing to the solubility of methacrylic acid in water, no uniform copolymers with water-insoluble ones Vinyl compounds are formed, but masses which, when dissolved in alkali, become cloudy and flaky, thus deliver solutions containing various components. In contrast, the Process of the present application homogeneous

ίο Get copolymers that differ thanks to their uniformity Dissolve water-clear in alkalis.

According to another literature, the polymerization of amides of the acrylic acid series excretion of polymerization products in aqueous solution, which can be dissolved by neutralization. It has now been found that the polymerization of methacrylic acid amide in aqueous solution in the presence from about 5% acrylic acid slimy white masses arise, from which, however, a solid polymer does not arise can be separated, while granular, easily filterable products according to the present process can be obtained.

Claims (1)

Claim: Process for the production of granular polymethacrylic acid according to patent 749 016 by polymerization of methacrylic acid under mechanical agitation in an electrolyte solution of such concentration, that the monomeric methacrylic acid remains essentially undissolved, characterized in that that at most 80 percent by weight of methacrylic acid in the presence of at least 20 percent by weight of polymerizable monomers Ethylene derivatives, which result in water-insoluble polymers, are polymerized. Considered publications:
German Patent Nos. 656134, 675 032, 662157;
U.S. Patent No. 2,133,257. _ 1 609 S74 8.56