FI58780B - FREQUENCY REFRIGERATION FOR STABILIZATION OF VAT-I-OIL-EMULSIONER OF VAT-REQUIRED POLYMER - Google Patents

Description

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Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) P 2354006.9 (71) Bayer Aktiengesellschaft, Leverkusen, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Wilfried Keller, Opladen, Friedhelm Miiller, Odenthal, Federal Republic of Germany 7U) Oy Kolster Ab (5U) Method for preparing stable water-in-oil emulsions of water-soluble polymers - Förfarande för framställning av stabila vatten-i-olja-emulsioner av vattenlösliga polymerer

The invention relates to a process for the preparation of high molecular weight water-soluble polymers as stable water-in-oil emulsions (w / o emulsions).

Methods for polymerizing water-soluble monomers and mixtures thereof as a w / o suspension are known methods. In these methods, the aqueous monomer solutions are decomposed into a neutral oil phase with stirring to form a suspension of small beads and polymerized into bead-like products in the presence of a catalytic polymerization initiator. Such a method has the advantage that the polymer products can be obtained in beads of the desired size (cf. DE patents 1,081,228 and 1,300,244).

DE patent published! Also known from 1,089,173 is the reverse emulsion polymerization process, in which solid polymers and copolymers of water-soluble monomers are prepared as a w / o emulsion using peroxide catalysts. Furthermore, German patent publication 2,226,143 relates to stable polymer-containing w / o emulsions, 2,58780, which remain stable again with light movements. These w / o emulsions are prepared in the presence of the usual thermally decomposable radical generators acting as polymerization catalysts. The disadvantage of this method is that it yields only relatively small molecule polymers, as shown by the comparative experiments of this patent application.

Finally, it is also known to apply aqueous solutions of acrylic monomers as a thin layer to the surface of a hydrophobic support and to carry out the polymerization with the aid of UV light and photoinitiators. The polymer is then peeled from the support and ground (cf. DE 2 O 50 988).

The object of the present invention has been to prepare ν / δ latexes with high solids concentrations of very high molecular weight water-soluble polymers.

The problem was solved by preparing a water-in-oil emulsion from at least one water-soluble, α, β-monoolefinically unsaturated monomer and initiating the polymerization with photoinitiators and UV light.

The invention thus relates to a process for the preparation of stable w / o emulsions of water-soluble polymers by polymerizing at least one water-soluble, e, β-monoolefinically unsaturated monomer in a water-in-oil pre-emulsion, characterized in that the polymerization of monomers in a w / o emulsion is initiated using at least one an aqueous or oil phase soluble light initiator and UV light.

Based on current technical knowledge, it was expected that the process of the invention would only yield polymers of medium molecular weight. Surprisingly, however, products with very high molecular weights were obtained, as shown by a comparison of the viscosities of aqueous solutions of the same concentration prepared by different methods.

As used herein, water-soluble monomers refer to monomers from which or at least 2% by weight of aqueous solutions can be prepared at 25 ° C.

Examples of water-soluble compounds include: l) water-soluble carboxylic acids having 3 to 6, preferably 3 to 4 carbon atoms such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, aconitic acid or the alkali and ammonium salts of the above acids, ,, methacrylic acid and maleic acid; 5 58780 2) water-soluble, primary, secondary or tertiary aminoalkyl esters of (meth) acrylic acid having 2 to 4 carbon atoms in the alkyl residue, for example dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, ) acrylate or salts thereof with inorganic or organic acids such as hydrochloric acid, acetic acid, etc., mainly dimethylaminoethyl (meth) acrylate; 3) methacrylamide, acrylamide; 4) dialkylaminoalkyl (meth) acrylamides having 1-2 C atoms in the alkylamine group and 1-4 C atoms in the second alkyl group, or their salts with inorganic or organic acids such as hydrochloric acid, acetic acid, etc., such as dimethylaminomethyl ( meth) acrylamide;

It is particularly preferred to polymerize I. 60-90 by weight of 96 acrylamide or methacrylamide or mixtures thereof and II. 40-10% by weight of dimethylaminoethyl acrylate hydrochloride, diethylaminoethyl acrylate hydrochloride, dimethylamino-n-propyl acrylate hydrochloride, diethylamino-n-propyl acrylate hydrochloride or similar methacrylic compounds of the above or the like methacrylic compounds.

The monomer and / or their salts are used in the process according to the invention in the form of 20 to 80% by weight, preferably 50 to 70% by weight, of aqueous solutions.

the oily phase can be any liquid which does not dissolve the monomers used and which does not mix with water! Liquid aliphatic and aromatic hydrocarbons and their substituted products and mixtures are preferably used. Mention should be made of the following: benzene, toluene, xylene, decalin, tetralin, mineral oils, kerosene, kerosene, isoparaffins, petrol, white spirit, xylene mixtures or mixtures thereof.

the weight ratio of the oil phase to the aqueous phase containing the monomer can vary within wide limits between 3: 1 and 1: 2.5, depending on the monomers used ·

All known w / o emulsifiers can be used to emulsify the aqueous phase into the oil phase, usually emulsifiers with low HLB values of 4,58780 [Hydrophile-Lipophile-Balance (cf. Atlas Chemical Industries, 1963 »" Das Atlas HLB-system ")]. . Particularly suitable are: sorbitan fatty acid esters such as sorbitan monooleate, etearate, laurate, palmitate, polyoxyethylene sorbitan fatty acid esters, i.e. reaction products of one said mole of sorbitan fatty acid ester and 4-40 moles of ethylene oxide, polyoxyethylene sorbitol esters of fatty and rosin acids and mixtures thereof. Their application rates, depending on the oil phase, are 5-20 weight- $.

Suitable photoinitiators are the compounds usually used for this purpose, for example benzophenone, as well as the very common aromatic keto compounds which are derivatives of benzophenone, such as alkylbenzophenones, halomethylated benzophenones according to DE 1 949 010, bisophenone halides, Michler's ketone, anthrone. Also suitable are benzoin and its derivatives, for example the compounds according to DE 1 769 168, 1 769 853, 1 769 854, 1 807 297, 1 807 301, 1 919 678 and DE 1 694 149. Efficient photoinitiators also include anthraquinone and its numerous derivatives, for example β-methylanthraquinone, tert-butylanthraquinone and anthraquinone carboxylic acid esters, as well as the oxime esters according to DE 1 795 089.

Particularly useful are benzoin and its alkyl ethers such as methyl ether, ethyl ether, propyl ether, iopropyl ether; aromatic acylines having a substituent in the α-position or their ethers such as alkali metal salts of o-propionic acid benzoyl ethyl ether.

The photoinitiators are used, based on the amount of monomer used, from 0.005 to 10% by weight, preferably from 0.01 to 0.1% by weight. One or more intermediate nitrators may be used in the process.

When performing photopolymerization, artificial radiators with an emission in the range of 1500-5000 1, mainly in the range of 3000-4000 Å, can be used as radiation sources. Preferred are mercury vapor, xenon and Wolfram lamps, illuminator tubes, carbon arc lamps, but also sunlight, especially illuminator tubes.

The method according to the invention can be implemented as both a non-continuous and a continuous method. Usually, aqueous solutions of monomers are first emulsified under high gravity under the action of an oil phase, which generally contains w / o emulsifiers. The photoinitiators used can - depending on their solubility - be both in the aqueous solution of the monomer and also in the oil phase.

5,58780 The w / o emulsion thus obtained is irradiated with light, whereby the polymerization of the monomers takes place almost quantitatively. Dissipation of the heat of polymerization can take place either by using external cooling or by evaporating part of the oil phase, for example by using reflux cooling.

The distance of the light source from the reaction mixture depends on the intensity of the light source, the irradiation time, the quality of the initiator and, in continuous processes, the rate of the reaction in the reaction tube. It can be about 1 cm -100 cm. The thickness of the layer of polymerizable w / o emulsion is mainly 0.5 to about 20 cm, depending on its light transmittance. Essentially, the light source or light sources are immersed in a polymerization mixture (w / o emulsion).

The irradiation time depends on the quality and concentration of the monomers used, the intensity and density of the light source, the thickness of the layer to be polymerized, the quality and amount of photoinitiators used, and can range from a few seconds to several hours, preferably from about 10 minutes to 3 hours.

The polymerization temperatures can be freely selected from a wide range. They are mainly between -10 ° C and about 100 ° C. In a particularly preferred embodiment of the present invention, the polymerization is carried out at room temperature (t 20-25 ° C) without adding heat.

The concentrations of the polymers in the w / o emulsion can vary within wide limits. The resulting w / o emulsion generally has a polymer content of 10 to 50% by weight.

The polymer can be recovered therefrom either by blending with acetone, methanol, etc .; mainly it remains as very fine gel particles in a stable w / o emulsion and can be used in this form in papermaking (retention aid). The products according to the invention can also be used as coagulants in the treatment of waste water.

The percentages mentioned in the following examples refer to weight percentages.

Example 1 Oil phase: 150.00 g of decalin 20.00 g of sorbitan monostearate 0.02 g of benzoin isopropyl ether

Aqueous phase: 93.7 g of acrylamide 6.3 g of methacrylic acid 109.2 g of water.

The aqueous phase was emulsified with an efficient mixer into the oil phase to form a stable w / o emulsion.

Light source: Philips-Leuchtstoffröhre TL 05/6 W.

6 58780

Test set-up: The upright glass tube had a concentric UV light source. In order to better dissipate the heat of reaction, the temperature of the reaction vessel was adjusted on the outside with a water jacket, on the inside by cooling the UV light source with water. The temperature of the reaction mixture was 20 ° C at the beginning of the polymerization.

Polymerization: After the monomer emulsion was placed in the test apparatus, it was purged to remove oxygen residues with nitrogen for about 30 minutes and then the TJV lamp was ignited. A reasonable nitrogen flow was also maintained during the polymerization. The temperature rose to about 40 ° C during polymerization. Irradiation time: 20 minutes.

The reaction product was an inseparable, stable latex with a polymer content of 26.0 and an average particle diameter of 0.2. A portion of the latex was poured into acetone and the precipitated polymer was filtered off, washed with acetone and dried in vacuo at 60 ° C. The Brookfield viscosity of a 0.5% aqueous solution of the polymer prepared by this method at 20 ° C was 290 cP in the acidic range (pH 3 → 4) and 5800 cP in the alkaline range (pH 10.0).

In contrast, the Brookfield viscosity value (in the alkaline range) of a 1% aqueous solution of the same polymer with an identical monomer composition, the preparation of which is described in German Patent Specification 2,226,143 (Example 1), is only 150 cP.

Example 2 Oil phase: As in Example 1 93.4 g of acrylamide 6.6 g of acrylic acid 110.2 g of water

Execution of the experiment as in Example 1.

A stable latex with a polymer content of 26.3% by weight was obtained. The Brookfield viscosity of a 0.5% aqueous solution of the obtained polymer at 20 ° C was 350 cP in the acidic range (pH 3 * 1) and 5000 cP in the alkaline range (pH 10.5). In contrast, the viscosity of even a 1% aqueous solution of a polymer of identical monomer composition is reported in German Patent Publication 2,226,143 (Example 2) in the alkaline range of butter to 225 cP.

Example 3 oil phase: 180.4) 0 g decalin 20.00 g eorbitan monooleate 20.00 g xylene 0.02 g benzoin isopropyl ether 7 58780

Aqueous phase: 100.00 g of acrylamide 100.00 g of water

Execution of the experiment as in Example 1.

Irradiation time: 20 minutes.

The resulting w / o emulsion had a polymer content of 23.8% by weight.

Brookfield viscosity of a 0.5% aqueous solution: 210 cP.

The Brookfield viscosity of a 0.5% aqueous solution of polyacrylamide prepared by a comparable inverse emulsion polymerization process according to German Patent Specification 1,089,175 (Example 1) is reported to be only 24 * 6 cP.

Example 4 Oil phase: 100.00 g chlorobenzene 15.00 g sorbitan monopalmitate 100.00 g decalin

Aqueous phase: 100.00 g of acrylic acid 0.03 g of the Na salt of α-propionic acid benzoyl ethyl ether 50.00 g of water.

Execution of the experiment as in Example 1.

The pH of the aqueous phase was adjusted to 5 with concentrated aqueous ammonia. · Irradiation time: 2 hours.

Brookfield viscosity of a 0.5% aqueous solution: at pH 65-1500 cP

At a pH of 9 * 0 21,500 cP

Example 5 Oil phase: 50.00 g xylene 50.00 g decalin 10.00 g sorbitan monooleate 0.02 g benzoin isopropyl ether Aqueous phase: 70.00 g acrylamide 30.00 g N, N-dimethylaminoethyl methacrylate 25.00 g water.

Execution of the experiment As in Example 1, the pH of the aqueous phase was adjusted to 6 with 36% hydrochloric acid.

Light source: Philips Leuchtstoffröhre TL · 05/6 W.

Irradiation time: 30 minutes, polymer content of the w / o emulsion: 40.5 wt-56 The Brookfield viscosity of a 0.5% aqueous solution at pH 4.0 was 3880 cP.

ov · '' β 58780

Example 6 oil phase: 50.00 g tetralin 50.00 g decalin 10.00 g sorbitan monostearate

Aqueous phase: 73 »50 g of acrylic acid 50.20 g of maleic acid 0.05 g of the Na salt of α-propionic acid ethyl ether 80.00 g of concentrated aqueous ammonia (26 ft)

The pH of the aqueous phase was adjusted to 5 * by adding a further concentrated aqueous ammonia solution. In other respects, the experiment was performed according to Example 1. Light source: mercury high pressure lamp.

Irradiation time: 60 minutes.

Latex polymer content: 55 wt.

The Brookfield viscosity of the 0.5% aqueous solution at pH 6 was 490 cP.

Claims (2)

9,58780 A process for preparing stable water-in-oil emulsions of water-soluble polymers by polymerizing at least one water-soluble monoolefinically unsaturated monomer in a water-in-oil emulsion, characterized in that one or more monomers belonging to the following groups: 1) «fy / 5- mono-olefinically unsaturated carboxylic acids having 1 to 6 carbon atoms; 2) primary, secondary or tertiary aminoalkyl esters of (meth) acrylic acid, the alkyl moiety of which contains 2 to 4 carbon atoms; 3. methacrylamide, acrylamide and 4. dialkylaminoalkyl- (meth) acrylamide, the alkylamino part of which contains 1-2 carbon atoms and the other alkyl part of 1 to 4 carbon atoms or a mixture thereof in a polymerization-water-oil emulsion Initiating at least one water or oil tree by means of a soluble photoinitiator and UV light and that the monomers or their salts are used as an aqueous solution of 20 to 80% by weight, the weight ratio of the oil phase to the aqueous phase being between 3 * 1 and · 1: 2.5 · Process according to Claim 1, characterized in that I. 60 to 90% by weight of (meth) acrylamide or a mixture II thereof are used. 40-10 parts by weight of dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylamino-n-propyl (meth) acrylate or diethylamino-n-propyl (meth) acrylate or a mixture thereof.