JPS5867706A - Manufacture of copolymer from monoethylenically unsaturated mono- and dicarboxylic acid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel process for the preparation of copolymers of monoethylenically unsaturated mono- and dicarboxylic acids by radical copolymerization of mono- and dicarboxylic acids in an aqueous medium.

According to West German Patent Application No. 2i6984, a copolymer of maleic acid and acrylic acid is known which is used as a crust formation inhibitor in detergents and cleaning agents.
No specific method for preparing this polymer is described therein.

In West German Patent Application No. 2212623,
A method is described in which the copolymerization of maleic anhydride and acrylic acid is carried out in Penzole as a solvent in the presence of benzoyl peroxide (see Example 3), which means that the polymer formed is insoluble in Penzol. This is a precipitation polymerization in which a substance precipitates during formation. The disadvantage of this method is that it requires the use of penzole, which subsequently has to be separated off again. In addition, polymers with too high molecular weights are formed, which has an adverse effect on their properties as anticrusting agents.

According to US Pat. No. 3,258,491, a method is known for the preparation of maleic anhydride/vinyl acetate copolymers by polymerization in water in the presence of a redox catalyst.

It is clearly mentioned in these documents that these methods are only successful if the pH range is precisely adjusted to 6-5. An improvement on the last method is disclosed in U.S. Patent No. 28.
According to No. 87480, during the copolymerization of (anhydrous) maleic acid and acrylic acid in an aqueous medium, a radical-forming initiator, such as potassium peroxydisulfate, is used in an amount of at least 17% by weight, based on the total amount of monomers. It is to be used in. This extremely high proportion of initiator
Even ignoring the large consumption of irreversibly decomposing chemicals, it has the disadvantage that the resulting polymers are chemically significantly altered due to the high supply of peroxo groups (incorporation of carboxyl functions and others).

The object of the present invention is a process for the preparation of copolymers of monoethylenically unsaturated mono- and dicarboxylic acids in an aqueous medium, comprising:
The object of the present invention was to develop a process by which a product, which can be used in an optimal manner as an anticrusting agent, as described in the above-mentioned DE 29 36 984, could be produced in the least expensive way possible.

Furthermore, the process should be specifically optimized to the extent that the residual amount of monomer dicarbonate edges is as low as 1.5% by weight or less. For monocarboxylic acids this problem does not arise as they are almost 1.00% polymerized (acrylic acid or methacrylic acid).

The present invention comprises (a) 10 to 60% by weight of a monoethylenically unsaturated dicarboxylic acid having 4 to 6 carbon atoms, an alkali metal salt thereof or optionally an anhydride thereof;
90-40% by weight of a monoethylenically unsaturated monocarboxylic acid or its alkali metal salt having 5 carbon atoms and (C
) Other carboxyl group-free monoethylenically unsaturated monomers copolymerizable with monomers (a) and (b) 0 to 20
% by weight (both based on the total amount of monomers) in an aqueous medium in the presence of a water-soluble initiator of 0.5 to 5% by weight relative to the monomers, dicarboxylic acids, their salts or their anhydrides in an aqueous medium. and the monocarboxylic acid or its salt together with the initiator for 6 to 10 hours.
in the presence of a water-soluble initiator in an aqueous medium, characterized in that monocarboxylic acids and dicarboxylic acids or their intramolecular anhydrides are copolymerized by reacting at °C and optionally saponifying the anhydride groups. By copolymerizing with
This is a method for producing a copolymer containing monoethylenically unsaturated mono- and dicarboxylic acids as one monomer unit.

The starting monomer (a) of the process of the invention is a monoethylenically unsaturated dicarboxylic acid, a salt thereof, or an anhydride thereof if the spatial position of the carboxyl group permits (cis position);
The last one is preferably used. Suitable dicarboxylic acids having 4 to 6 carbon atoms are, for example, maleic acid, itaconic acid, mesaconic acid, fumaric acid, methylenemalonic acid or citraconic acid. Preference is given to using maleic acid or maleic anhydride.

Starting monomer (b) is a monoethylenically unsaturated monocarboxylic acid or a salt thereof. They have 3 to 10 carbon atoms in the molecule. Particular mention may be made of acrylic acid or methacrylic acid, but it is also possible to use vinylacetic acid or the 02-C4-alkyl half esters of the aforementioned dicarboxylic acids, especially maleic acid. Mixtures from groups (a) and (b) may also be used.

In the present invention, the "salts" of the carboxylic acids listed in (a) and (b) refer to alkali metal salts, preferably sodium salts, potassium salts, ammonium salts, or salts of organic amines, such as) means a c4-alkylamine salt or a seven-, di-, or tri-, ~C4-alkanolamine salt, or a mixture thereof. For simplicity, it will also be referred to as "salt" below.

Among the suitably used alkali metal salts, it is preferable to choose the most easily available one, ie, the sodium salt or potassium salt, especially the sodium salt.

Starting monomer (C) that does not necessarily need to be polymerized
is a carboxyl group-free, preferably water-soluble monomer copolymerizable with monomers (a) and (b). Examples include acrylamide, methacrylamide, acrylamide sulfo/acid, vinylsulfonic acid, allylsulfonic acid, vinylphosphonic acid, allylphosphonic acid, vinyl acetate, hydroxyethyl- or -probyl acrylate, vinyl glycol or acrylic or methacrylic acid. Examples include methyl esters of acids. The sulfonic acids and phosphonic acids described above may optionally be described in claim 6.
It can also be used in the form of an alkali metal salt and/or an ammonium salt and/or an amine salt, taking into consideration the degree of neutralization according to the present invention as described in 2.

Monomer (a) is present in the mixture in an amount of 60 to 10% by weight, preferably 45 to 20% by weight, monomer (b) in an amount of 40 to 90% by weight, preferably 55 to 80% by weight. Monomer (C) can be used in an amount up to 20% by weight.

Water-soluble radical-forming initiators are, for example, hydrogen peroxide itself, peroxydisulfate, especially sodium or ammonium peroxydisulfate, or azo-bis-(2-aminopropane)-hydrochloride. Preferably hydrogen peroxide is used.

According to the invention, the amount of initiator is 0.5 based on the total amount of monomers.
~5% by weight is added to the mixture.

Polymerization takes place in an aqueous medium. In this case, the concentration of the aqueous solution should be 20 to 70% by weight of all monomers, preferably 40 to 70% by weight.
It is preferable to select the content to be 60% by weight.

In addition, regulators customary in free-radical polymerizations in aqueous media, such as thioglycolic acid or C1-C4-aldehydes, or chain extenders, such as methylenebisacrylamide or divinyl glycol, are added, in each case from 0.1 to 2 ml, based on the total amount of monomers. It can also be added to the mixture in amounts of 0.5-5% by weight as well as 0.5-5% by weight.

The polymerization is carried out as follows. That is, first, an aqueous solution of dicarboxylic acid, its salt and/or anhydride is charged,
Subsequently, the monocarboxylic acid or its alkali metal salt and the initiator are preferably likewise fed in as an aqueous solution over a period of 3 to 10 hours, preferably 5 to 8 hours. It is often particularly advantageous to add small amounts of component (b) together with small amounts of initiator directly to the initial charge of component (a). The reaction temperature can vary within a wide range; preferably temperatures from 60 to 150°C, especially from 100 to 130°C are chosen. As the reaction vessel, a pressure-resistant vessel such as an autoclave is selected when operating at a temperature higher than the boiling temperature of water.

After the end of the polymerization, if the pH range was not so chosen during the polymerization, it can be made weakly alkaline or strongly alkaline depending on the intended use, if starting from anhydride or if anhydride is present in the mixture. In some cases, it is hydrolyzed with anhydride groups.

The obtained aqueous polymer solution can also be mixed and processed into an agent for use as it is. Alternatively, the aqueous solution can be combined directly with an aqueous solution containing other detergent ingredients and subjected to conventional spray drying.

When operating within the scope of the preferred embodiment set out in claim 3, monomers (a) and (b)
- together i.e. (a) and (b) in a mixture of
) in total, care should be taken to ensure that 20-80%, preferably 60-70%, is neutralized.

This can be done by using dicarboxylic acids or parts thereof in the form of their salts and monocarboxylic acids in free form. However, it is also possible to operate vice versa and to use the dicarboxylic acids in free form or, if possible, as anhydrides, and the monocarboxylic acids in the form of their salts. Care is taken in each case that the ratio of free acid to salt corresponds to the total degree of neutralization as defined above.

This copolymer has a value of 8-100, often 10-600. This one is, for example, West German Patent Application Publication No. 2
It meets all the requirements for a good crusting inhibitor as described in No. 936984. This copolymer is
In particular when operating according to the preferred embodiment described in claim 6, it has an unreacted dicarboxylic acid content of less than 1.5%. This in itself was quite surprising since the opposite, ie poorer polymerization, would have been expected, especially when starting from alkali metal salts of dicarboxylic acids such as maleic acid. (As is known, maleic anhydride polymerizes better than free maleic acid or its alkali metal salts.

The present invention will be explained below with reference to Examples. The K value was determined at 25° C. in a 2% aqueous solution for completely neutralized salts by the Haher-Fekencher method (Zerrose Chemie Vol. 13, p. 60). The monomeric maleic acid was determined by the polarographic method (see "Bolarographical Issier Albeitsuntoden" by Emu Mark, Gruyter Verlag, 1950).

Example 1 A stirred 5-e special steel reactor is charged with 844 parts of maleic anhydride and 1200 parts of fully demineralized water.

The reactor is injected three times in succession with 5 bar of nitrogen and heated to 160° C. under pressure.

A mixture of 1000 parts of acrylic acid and 706 parts of fully demineralized water was then heated for 8 hours and 60% hydrogen peroxide
A mixture of 67 parts and 270 parts of fully demineralized water is uniformly fed over a period of 9 hours at 130°C. This is followed by heating to 130° C. for a further 2 hours. This clear, pale yellow polymer solution has a solids content of 44.3%. The value of this copolymer is 10.5. The residual monomer acrylic acid content is 1.
6% (calculated on solids content).

Example 2 588 parts of maleic anhydride and 1200 parts of completely demineralized water were charged into the same apparatus as in Example 1, and nitrogen was injected under pressure.
Heat to 0°C. A mixture of 1623 parts of acrylic acid and 997 parts of fully demineralized water was then added over a period of 6 hours, and 60%
A solution of 154.3 parts of hydrogen peroxide and 375 parts of fully demineralized water is fed at 110° C. over a period of 6 hours. followed by 120℃
and react at this temperature for 2 hours.

This clear yellow solution has a solids content of 45.3%;
This copolymer has a value of 200. The residual maleic acid content is 2.5%.

Example 3 In a 2-e reactor equipped with a stirred reflux condenser, 200 parts of fully demineralized water and 120 parts of maleic acid are mixed with 10
Heat to boiling temperature to 0°C. 480 parts of acrylic acid diluted with 100 parts of fully demineralized water are then fed in over 5 hours and 18 parts of 60% hydrogen peroxide dissolved in 100 parts of fully demineralized water are fed in over 6 hours. The reaction is then continued for a further 2 hours at 100°C. The clear, colorless solution has a solids content of 596%, and the copolymer has a pH value of 662. The residual monomer maleic acid content is 2.2%.

Example 4 1200 parts of maleic anhydride are charged into the same apparatus as in Example 1, nitrogen is injected under pressure, and the solution is heated to 120° C. under pressure. Next, 7 parts of completely demineralized water and 16 parts of acrylic acid
After 8 hours of a mixture of 24 parts and 10 hours of a solution of 609 parts of 60% hydrogen peroxide in 221 parts of fully demineralized water, the copolymer has an NH value of 1°4. The content of residual monomer maleic acid is 0.62%.

Example 5 In an 11 volume reactor equipped with a stirred reflux condenser,
141.1 parts of maleic anhydride and 240.9 parts of completely demineralized water
and boiling heat to about 100'C. A mixture of 615 parts of acrylic acid and 200 parts of fully demineralized water is then heated for 8 hours and sodium persulfate b in 50 parts of fully demineralized water is then heated to 100 DEG C. for a further 2 hours. The clear, colorless solution has a solids content of 69.7%, the copolymer has a copolymer value of 32 and a monomeric maleic acid content of 4%.

The following examples illustrate components (a), (b) and optionally (
Figure 2 shows a copolymer prepared according to a preferred embodiment by charging C) in partially neutralized form according to the invention.

General manufacturing guidelines: In a stainless steel reactor equipped with a stirrer, add the desired amount of dicarboxylic anhydride, dicarboxylic acid or fully or partially neutralized dicarboxylic acid (neutralized with NaOH) 1. Charge with 5 times the amount of fully demineralized water.

The reactor is flushed with nitrogen (5 pars) three times and heated to the desired temperature. A mixture of the desired amount of monocarboxylic acid or its sodium salt (depending on the desired total degree of neutralization) and 1.5 times the amount of fully demineralized water is then added over a period of 5 hours, and the desired amount of initiator ( (as a 60% aqueous solution) and 1.5 times the volume of fully demineralized water are uniformly fed over a period of 6 hours.・
This is followed by heating to the selected reaction temperature for a further 2 hours. Approximately 4
A 0% by weight solution is produced. The K values and residual dicarboxylic acid content as well as the specific reaction conditions are shown in the table below.

The symbols in the table have the following meanings.

AS - acrylic acid MS = maleic acid CS = citraconic acid = maleic acid ε; methyl ester VS - vinyl sulfonic acid (Na salt) AA = acrylamide HPA = hydroxypropyl acrylate Example 5.
8.9.10 and 11 are useful for comparison.

Continuation of page 1 Priority claim 01 December 1981 ■ West Germany (DE
) CP 3147489.6 @ Inventor Albrecht Herache Federal Republic of Germany 6717 Hesheim Kreis Strasse 12 0 Inventor Rolf Schneider Federal Republic of Germany 6800 Mannheim 1 Feldberg Strasse 21 @ Inventor Hansjuergen Laubenheimer Germany Federal Republic of 6834 Ketsch Benzstrasse 6

Claims (1)

[Scope of Claims] 1. (a) 10 to 60% by weight of monoethylenically unsaturated dicarboxylic acids having 4 to 6 carbon atoms, their alkali metal salts or optionally their anhydrides; (b) 3 to 10% by weight; 90 to 40% by weight of monoethylenically unsaturated monocarboxylic acid or its alkali metal salt having 5 carbon atoms and (C
) Other carboxyl group-free monoethylenically unsaturated monomers 0 to 2 copolymerizable with monomers (a) and (b)
0% by weight (all based on the total amount of monomers) in an aqueous medium in the presence of a water-soluble initiator of 0.5 to 5% by weight relative to the monomers, dicarboxylic acids, their salts or their anhydrides in an aqueous medium. and feed the monocarboxylic acid or its salt together with the initiator for 6 to 10 hours;
Monocarboxylic acids and dicarboxylic acids or their intramolecular anhydrides in the presence of a water-soluble initiator in an aqueous medium, characterized in that they are copolymerized by reacting at 0° C. and optionally saponifying the anhydride groups. A method for producing a copolymer containing monoethylenically unsaturated mono- and dicarboxylic acids as one monomer unit by copolymerizing the following. 2. Claim 1 characterized in that maleic acid is used as dicarboxylic acid in the form of anhydride, free acid and/or corresponding salt, and acrylic acid or methacrylic acid is used as monocarboxylic acid. The method described in. 6. Monomers (11) and (b) are combined with 2 during the polymerization reaction.
3. Process according to claim 1, characterized in that it is used in a neutralized form of 0 to 80%.