WO2000005273A1

WO2000005273A1 - Method for producing powder-shaped cross-linked polymerizates

Info

Publication number: WO2000005273A1
Application number: PCT/EP1999/004869
Authority: WO
Inventors: Volker Hildebrandt; Knut Breede; Katrin Zeitz
Original assignee: Basf Aktiengesellschaft
Priority date: 1998-07-23
Filing date: 1999-07-12
Publication date: 2000-02-03
Also published as: DE19833285A1

Abstract

The invention relates to a method for producing powder-shaped polymerizates by the radically initiated polymerization of monoethylenically unsaturated monomers selected from the group of monoethylenically unsaturated carboxylic acids, the amides and esters thereof, of N,N-diallyl amines and of N-vinyl monomers, or of mixtures of these monomers in the presence of cross-linking agents while using supercritical carbon dioxide as an inert solvent. The inventive method is characterized in that liquid carbon dioxide is firstly brought to the supercritical state in the reaction chamber by increasing the pressure to pressures greater than 73 bar and at a reaction temperature of up to 100 °C. The feed materials are then added in a dosed manner.

Description

Process for the preparation of powdered crosslinked polymers

description

The present invention relates to a process for the preparation of powdered polymers by radical polymerization of monoethylenically unsaturated monomers in supercritical carbon dioxide, if appropriate in the presence of crosslinking agents and substances which form free radicals, and the use of the polymers.

It is generally known to use supercritical carbon dioxide as a solvent in the preparation of polymers by radical polymerization. For example, EP-A 220 603 describes a process for producing uncrosslinked powdery polymers based on N-vinyl monomers and / or ethylenically unsaturated carboxylic acid esters by radical polymerization in supercritical carbon dioxide. EP-A 239 035 describes the preparation of crosslinked powdery polymers based on monoethylenically unsaturated carboxylic acids, their amides and / or esters by polymerization in supercritical carbon dioxide. In the known processes, the reaction mixture and liquid carbon dioxide are generally placed in a pressure vessel and the supercritical state is then brought about by increasing the temperature and pressure. The disadvantage of this, however, is that, due to the non-uniform solubility of the monomers and crosslinking agents in the solvent, products with a non-uniform morphology or a non-uniform chemical composition can result. In individual cases, undesired bulk polymerization of the feed materials can occur before the substances are dissolved. The object of the present invention was to find an improved process for the preparation of crosslinked polymers.

Accordingly, a process for the preparation of powdered polymers by free-radically initiated polymerization of monoethylenically unsaturated monomers, selected from the group of monoethylenically unsaturated carboxylic acids, their amides and esters, the N, N-diallylairine and the N-vinyl monomers, or mixtures of these monomers , found in supercritical carbon dioxide as an inert diluent, which is characterized in that the carbon dioxide in the reaction space is first increased to supercritical state by increasing the pressure to pressures above 73 bar and temperatures greater than 31 ° C. and brought to a reaction temperature of up to 100 ° C, and then metered in the feed.

The polymerization is carried out under pressure in supercritical carbon dioxide as an inert diluent. About the

Properties of carbon dioxide in liquid and in the supercritical state reported JA Hyatt, J. Orc. Chem. 49, 5097-5101 (1984). The critical point for carbon dioxide is then around 31 ° C and 73 bar. The polymerization is preferably carried out under pressure in supercritical carbon dioxide at temperatures above about 31 ° C., the critical temperature of the carbon dioxide. The upper limit for the preparation of the polymers is taken to be the temperature which is 10 ° C. above the beginning of the softening range of the respective resulting polymers. The upper value for this temperature limit is 150 ^C for most polymers. The polymerization is preferably carried out in the temperature range from 30 to 130 ° C. The reaction temperature need not be kept constant; you can also set a step or ramp-shaped temperature profile. It is advisable to start the reaction

Set temperatures in the range of 31 to 100 ^C C. The pressures are above 73 bar, preferably in the range from 80 to 300 bar, particularly preferably from 120 to 250 bar.

The process according to the invention is characterized in that carbon dioxide in a solid, liquid or gaseous state is initially introduced into the reaction chamber in conventional pressure apparatus, then by increasing the pressure to values above 73 bar and the temperature to values above 31 ° C. the carbon dioxide transferred to the supercritical state, then the reaction temperature is set and then the starting materials are metered in. The supercritical carbon dioxide can also be introduced into the reaction space and then metered in.

The starting materials such as monomers, free radical initiators, crosslinking agents and optionally polymerization regulators can be metered in individually or as mixtures. For example, it may be advisable to dissolve the radical initiators in the compounds. Which procedure is chosen essentially depends on the solubility of the individual components among one another and in the diluent. If required, feedstocks can be metered in during the reaction (semi-batch procedure).

The polymerization reaction is started with the aid of polymerization initiators which break down into free radicals. All initiators known for the polymerization of the monomers can be used. For example, in Free radical initiators that have half-lives of less than 3 hours at the temperatures selected. If the polymerization is carried out at different temperatures, by polymerizing the monomers first at a lower temperature and then polymerizing them out at a significantly higher temperature, it is expedient to use at least two different initiators which have a sufficient rate of disintegration in the temperature range chosen in each case.

Based on 100 parts by weight of the monomer mixture, 100 to 3000, preferably 200 to 1500 parts by weight of carbon dioxide are used. It is preferably anhydrous. The polymerization reaction can be carried out batchwise or continuously with thorough mixing of the reactants in appropriately designed printing apparatuses. In order to dissipate the heat generated during the polymerization, it is desirable for the printing apparatus to have a cooling system. Of course, they must also be heatable in order to heat the reaction mixture to the temperature desired for the polymerization. The pressure equipment should have mixing devices, e.g. Stirrers (blade, impeller, multi-stage impulse counterflow, spiral stirrers) or blades.

Powdered crosslinked or uncrosslinked polymers of the following composition can be prepared by the process according to the invention:

(a) 60 to 99.99% by weight of a monoethylenically unsaturated monomer selected from the group consisting of monoethylenically unsaturated carboxylic acids, their amides and / or their esters with amino alcohols, the N-N-diallylamines and N-vinyl monomers or mixtures of these monomers,

(b) 0 to 10, preferably 0.001 to 10% by weight of at least two ethylenically unsaturated crosslinking monomers, and

(c) 0 to 30% by weight of further free-radically polymerizable monoethylenically unsaturated monomers.

Monoethylenically unsaturated carboxylic acids come into consideration as monomers of group (a). The most important representatives of this group are, for example, monoethylenically unsaturated C ₃ - to Cs carboxylic acids, such as acrylic acid, methacrylic acid, vinyl acetic acid, itaconic acid, crotonic acid, alpha-methylcrotonic acid, alpha-ethyl acrylic acid, dimethylacrylic acid, alpha-chloro acrylic acid and Vinyl lactic acid. The amides of monoethylenically unsaturated carboxylic acids, for example acrylamide, methacrylamide, crotonic acid amide and itaconic acid amide, are also suitable. The monomers of group (a) also include esters of monoethylenically unsaturated carboxylic acids and amino alcohols of the formula (I)

HO - R - N (I),

"^ R2 in the R = C - to Cg-alkylene,

Ri, R ² = H, CK ₂ , C ₂ H ₅ , C ₃ H ₇ . These are preferably di-Ci to C ₃ -alkylamino-C ₂ to C ₈ -alkyl acrylates or methacrylates. Individual representatives of these monomers are, for example, dimethylaminoethyl acrylate, dirnethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, dipropylaminoethyl acrylate, dimethyl aminopropyl acrylate, dimethyl aminopropyl methacrylate, dimethyl aminopethyl acrylate, methyl amyl methacrylate, dimethylamethyl amyl methacrylate, dimethylamethyl amyl methacrylate,

N, N-diallylamines of the general formula (II) are also suitable,

i

R ^

wherein R ^{4 is} a -C ₂₄ alkyl radical, preferably N, N-diaiiyl-N-methylamine.

Such diallylamines react under the polymerization conditions according to the invention with ring closure:

Of the monomers of group (a), preference is given to using acrylic acid, methacrylic acid, acrylamide and / or methacrylamide. If acrylic acid is used as monomer (a), crosslinked polyacrylic acid is obtained by copolymerization with the monomers of group (b), and accordingly the use of acrylamide as monomer of group (a) provides crosslinked polyacrylic mide. Puts If mixtures of acrylic acid and acrylamide are used as monomers of group (a), crosslinked copolymers of acrylamide and acrylic acid are obtained in the copolymerization. A further variation of the crosslinked copolymers is made possible by subjecting either acrylic acid additionally to the copolymerization in the presence of dimethylaminoethyl acrylate or acrylamide in the presence of dimethylaminoethyl acrylate together with the monomers (b) and optionally the monomers of group (c). Since the monomers of group (a) can be copolymerized with one another in any ratio, there are a variety of possible variations in the composition of the crosslinked copolymers.

Also suitable as monomers (a) are N-vinyl monomers such as N-vinyl lactams, for example N-vinyl pyrrolidone or N-vinyl caprolactam, N-vinyl carboxamides which are derived from saturated ci to C ₆ ~ carboxylic acids, for example N-vinyl formamide, N- Vinyl-N-methylformamide, N-vinyl acetamide, N-vinyl-N-methylacetamide, N-vinyl propionamide, N-vinyl-N-methyl propionamide, N-vinyl butyramide or N-vinyl capronamide as well as N-vinyl imidazole and 2-methyl N-vinylimidazole.

Suitable crosslinkers (monomers (b)) are, for example, acrylic esters, methacrylic esters, allyl ethers or vinyl ethers of at least dihydric alcohols. The OH groups of the underlying alcohols can be wholly or partially etherified or esterified; however, the crosslinkers contain at least two ethylenically unsaturated groups.

Examples of the underlying alcohols are dihydric alcohols, such as 1,2-ethanediol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, but-2-en-1,4-diol , 1, 2-pentanediol, 1, 5-pentanediol, 1, 2-hexanediol, 1, 5-hexanediol, 1, 10-decanediol, 1, 2-dodecanediol, 1, 12-dodecanediol, neopentyl glycol, 3-methylpentane -1, 5-diol, 2, 5-dodecanediol, 1, 12-dodecanediol, neopentyl glycol, 3-methylpentane-l, 5-diol, 2, 5-dimethyl-l, 3-hexanediol, 2,2, 4-trimethyl -l, 3-pentanediol, 1, 2-cyclohexanediol, 1,4-cyclohexanediol, 1, 4-bis (hydroxymethyl) cyciohexane, hydroxypivalic acid - neopentyl glycol monoester, 2, 2-bis (4-hydroxyphenyl) propane, 2, 2 -Bis [4- (2-hydroxypropyl) phenyl] propane, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 3-thio-pentane-1,5-diol, and also polyethylene glycols, polypropylene glycols and polytetrahydrofurans with molecular weights of 200 to 10,000 each. In addition to the homopolymers of ethyl Lenoxide or propylene oxide can also be block copolymers of ethylene oxide or propylene oxide or copolymers which contain ethylene oxide and propylene oxide groups. builds included, used. Examples of underlying alcohols with more than two OH groups are trimethylolpropane, glycerol, pentaerythritol, 1,2, 5-pentanetriol, 1, 2, 6-hexanetriol, triethoxycyanuric acid, sorbitan, sugars such as sucrose, glucose, mannose. Of course, the polyvalent ones Alcohols can also be used as the corresponding ethoxylates or propoxylates after reaction with ethylene oxide or propylene oxide. The polyhydric alcohols can also first be converted into the corresponding glycidyl ethers by reaction with epichlorohydrin.

Further suitable crosslinkers are the Vinylester or the esters of monohydric unsaturated alcohols with ethylenically unsaturated C _ß -CG-carboxylic acids, for example acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid. Examples of such alcohols are allyl alcohol, l-buten-3-ol, 5-hexen-l-ol, l-octen-3-ol, 9-decen-l-ol, dicyclopentenyl alcohol, 10-undecen-l-ol, cinnamon alcohol , Citronellol, crotyl alcohol or cis-9-octadecen-l-ol. However, the monohydric, unsaturated alcohols can also be esterified with polybasic carboxylic acids, for example malonic acid, tartaric acid, trimellitic acid, phthalic acid, terephthalic acid, citric acid or succinic acid.

It is also possible to use esters of unsaturated carboxylic acids with the polyhydric alcohols described above, for example oleic acid, crotonic acid, cinnamic acid or 10-undecenoic acid, as crosslinking agents.

Also suitable are straight-chain or branched, linear or cyclic, aliphatic or aromatic hydrocarbons which have at least two double bonds which must not be conjugated to aliphatic hydrocarbons, e.g. Divinylbenzene, divinyltoluene, 1, 7-octadiene, 1, 9-decadiene, 4-vinyl-1-cyclohexene, trivinylcyclohexane or polybutadienes with molecular weights from 200 to 20,000.

Also suitable as crosslinking agents are the acrylic acid amides, methacrylic acid amides and N-allylamines of at least divalent amines. Such amines are, for example, 1,2-diaminomethane, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane,

1, 6-diaminohexane, 1, 12-dodecanediamine, piperazine, diethylenetriamine or isophoronediamine. The amides of allylamine and unsaturated carboxylic acids, such as acrylic acids, methacrylic acid, itaconic acid, maleic acid, or at least dibasic carboxylic acids, as described above, are also suitable. Triallylamine and trialiylmonoalkylammonium salts, for example triallylmethylammonium chloride or methylsulfate, are also suitable as crosslinking agents.

Also suitable are N-vinyl compounds of urea derivatives, at least dihydric amides, cyanurates or urethanes, for example urea, ethylene urea, propylene urea or tartaric acid diamide, e.g. N, N 'divinyl ethylene urea or N, N' divinyl propylene urea.

Also suitable are alkylenebisacrylamides such as methylenebisacrylamide and N, N '- (2,2-) butane and 1, 1' -bis- (3, 3 '-vinylbenzimidazolite-2-one) 1,4-butane.

Other suitable crosslinking agents are, for example, alkylene glycol di (meth) acrylates, such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, tetraethylene glycol acrylate, tetraethylene glycol dimethacrylate, diethylene glycol acrylate, diethylene glycol methacrylate, vinyl acrylate, allyl acrylate, plylyl methacrylate, allyl methacrylate and allyl methacrylate, allyl methacrylate and allyl methacrylate.

Other suitable crosslinkers are divinyldioxane, tetraallylsilane or tetravinylsilane.

Crosslinking agents which are particularly preferably used are, for example, methylenebisacrylamide, triallylamine and triallylalkylammonium salts, divinylimidazole, N, N'-divinylethyleneurea, reaction products of polyhydric alcohols with acrylic acid or methacrylic acid, methacrylic acid esters and acrylic acid esters of polyalkylene oxides or polyhydric alcohols or with ethylene oxide and / Propylene oxide and / or epichlorohydrin have been implemented. Methylene bisacrylamide, N, N'-divinylethylene urea and acrylic acid esters of glycol, butanediol, trimethylolpropane or glycerol or acrylic acid esters of glycol, butanediol, trimethylolpropane or glycerol reacted with ethylene oxide and / or epichlorohydrin are very particularly preferred as crosslinking agents.

The crosslinker is preferably soluble in the reaction medium. If the solubility of the crosslinking agent in the reaction medium is low, it can be dissolved in a monomer or in a monomer mixture or else added in solution in a solvent which mixes with the reaction medium. Those crosslinkers which are soluble in the monomer mixture are particularly preferred.

The solution viscosity of the polymers according to the invention can be influenced to a large extent by the content of crosslinking agent. To modify the crosslinked copolymers, other ethylenically unsaturated monomers can be used in the copolymerization. The group of monomers (c) includes, for example, acrylonitrile, methacrylonitrile, acrylic acid and methacrylic acid esters which are derived from monohydric - to -C ₈ -alcohols, hydroxy-C ₂ - to C ₄ -alkyl esters of acrylic acid and methacrylic acid, maleic anhydride, Vinyl ester, 2-acrylamido-2-methylpropyl sulfonic acid and / or vinyl phosphoric acid. In addition, esters of acrylic acid and methacrylic acid with fatty alcohol ethoxylates and fatty alcohol propoxylates are suitable, the fatty alcohol component having 10 to 20 carbon atoms and the ethylene oxide or propylene oxide content being 1 to 20 mol%. Such alcohol components are obtained, for example, by reacting CI _Q to C ₂ o fatty alcohols with ethylene oxide and / or propylene oxide and esterifying the alkoxylated fatty alcohols obtained with acrylic acid or methacrylic acid. The use of these comonomers results in crosslinked copolymers which have a high resistance to electrolytes. The monomers of group (c) are used in an amount of 0 to 30, and preferably up to 15% by weight. If they are used for the modification of the copolymers from (a) and (b), the lower limit is 5% by weight, based on the monomer mixture. The sum of the percentages for the monomers (a), (b) and (c) is 100% in all cases. Esters of acrylic acid and methacrylic acid are, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, stearyl acrylate, stearyl methacrylate and the acrylic acid esters of the isomeric butyl alcohols. Hydroxy-C _{2 to} C ₄ -alkyl esters of acrylic acid and methacrylic acid are, for example, hydroxyethyl acrylates, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate and hydroxybutyl methacrylate. Of the vinyl esters, vinyl acetate and vinyl propionate are preferably used. Other suitable monomers are olefins such as ethylene or propylene, styrene and alkylethylene glycol acrylates or methacrylates with 1 to 50 ethylene glycol units.

Water-soluble and water-insoluble peroxo and / or azo compounds can be used as initiators for the radical polymerization, for example alkali metal or ammonium peroxydisulfates, hydrogen peroxide, dibenzoyl peroxide, tert-butyl perpivalate, tert. -Butyi-per-2-ethylhexanoate, 2, 2 '-azo-bis (2, 4-dimethylvaleronitrile), tert. -Butyl peroxineodecanoate, di-tert. -butyl peroxide, tert. -Butyl hydroperoxide, azo-bis-isobutyronitrile, azo-bis- (2-amidinopropane) dihydrochloride or 2, 2'-azo-bis- (2-methylbutyronitrii). Initiator mixtures or redox initiator systems, such as, for example, ascorbic acid / iron (II) sulfate / sodium peroxodisulfate, are also suitable. -Butyl- hydroperoxide / sodium disulfi, tert. -Butyl hydroperoxide / sodium hydroxymethanesulfanate. The initiators can be used in the customary amounts, for example 0.05 to 7% by weight, based on the amount of the monomers to be polymerized.

By using redox coinitiators, for example benzoin, dimethylaniline and organically soluble complexes and salts of heavy metals such as copper, cobalt, manganese, nickel and chromium or in particular iron, the half-lives of the peroxides mentioned, in particular the hydroperoxides, can be reduced , so that, for example, tert. -Butyl hydroperoxide in the presence of 5 ppm copper (II) acetylacetonate is already effective at 100 ° C.

Poorly water-soluble or water-insoluble initiators are preferably used.

The polymerization can optionally also be carried out in the presence of polymerization regulators in order to regulate the molecular weight of the polymers. If particularly low molecular weight copolymers are to be produced, higher amounts of polymerization regulators are used, while only small amounts of polymerization regulators are used for the production of high molecular weight copolymers or the absence of these substances is used. Suitable polymerization regulators are, for example, 2-mercapto-ethanol, mercaptopropanols, mercaptobutanols, thioglycolic acid, N-dodecyl mercaptan, tert. -Dodecyl mercaptan, thiophenol, mercaptopropionic acid, allyl alcohol and acetaldehyde. The polymerization regulators are used in an amount of 0 to 10, preferably 0 to 5% by weight, based on the monomers used.

The polymers obtainable by the process according to the invention are suitable for use as viscosity modifiers (emulsifiers and dispersing assistants), as W / O and O / W emulsifiers and generally as process aids, finishing aids or as superabsorbents, and furthermore as detergent additives such as incrustation and Color transfer inhibitors, as retention aids in paper manufacture, as flocculants in water treatment or for use in the field of food technology, for example as filter aids or complexing agents.

The polymers are particularly suitable as thickeners and gelling agents in cosmetic formulations, especially hair cosmetic preparations such as hair treatments, hair lotions, hair rinses, hair emulsions, tip fluids, leveling agents for perms, 'hot oil treatment' preparations, setting lotions or hair sprays, especially in conditioners.

Depending on the area of application, the hair cosmetic preparations can be applied as a spray, foam, gel, gel spray or mousse.

The polymers are also suitable as auxiliaries in pharmaceutical formulations, for example as tablet disintegrants.

The polymers produced according to the invention are white, free-flowing powders with a uniform morphology, which have practically no tendency to stickiness.

Examples

General rule

Carbon dioxide was placed in an autoclave and brought to the supercritical state and to the reaction temperature by increasing the pressure and temperature. The starting materials were then metered in as a mixture in a single feed over the course of 10 minutes. The reaction mixture was stirred at 600 rpm. The residence time in the reactor was 10 hours. The mixture was then cooled to room temperature and let down. Loose, white powders were obtained, which had no tendency to aggregate, with particle sizes in the range from 10 to 500 μm.

The respective composition and the reaction conditions are given in the table below. The quantities given for the peroxo radical initiators each relate to 75% by weight solutions in aliphatics.

table

Claims

claims

1. Process for the preparation of pulverulent polymers by radical-initiated polymerization of monoethylenically unsaturated monomers, selected from the group of the monoethylenically unsaturated carboxylic acids, their amides and esters, the N, N-diallylamines and the N-vinyl monomers, or mixtures These monomers, if appropriate in the presence of crosslinking agents using supercritical carbon dioxide as an inert diluent, characterized in that carbon dioxide is initially in the supercritical state in the reaction space by increasing the pressure to over 73 bar and at a temperature of from 31 ° C. to 100 ° C brings, and then metered in the feed materials.

2. Use of the polymers, obtainable according to the process of claims 1, as auxiliaries in cosmetic or pharmaceutical formulations.