DE10323372A1 - Continuous method for selective hydrogenation of ethylenic double bonds in polymers to give hydrogenated butadiene-styrene type copolymers for use, e.g. as paint binders and finishes for textiles, leather and paper - Google Patents

Abstract

A method for the selective hydrogenation of ethylenic double bonds in polymers (P) by reaction with hydrogen in presence of a hydrogenation catalyst involves carrying out the reaction as a continuous process.

Description

The The present invention relates to a continuous process for selective hydrogenation of ethylenically unsaturated double bonds in At least polymers by reacting the polymers in the presence a hydrogenation catalyst, selected from the salts and complex compounds of ruthenium and rhodium.

The Hydrogenation of ethylenically unsaturated Double bonds represent an important process for derivatization of polymers containing ethylenically unsaturated double bonds, A number of such polymers are used on an industrial scale scale manufactured. Here are examples of polymers based of butadiene and / or isoprene. The in these polymers contained ethylenically unsaturated Double bonds are the starting points for aging processes like this occur under the influence of light, oxygen and / or temperature can. Such aging processes often have, depending on the degree of exposure, a dramatic deterioration in mechanical properties the polymers or the products produced from the polymers as well as striking and annoying discoloration result. By hydrogenation of the double bonds such Have weak points removed. In addition, the hydrogenation enables in principle the provision of polymer classes that are new and different are only much more complex to produce.

at When developing hydrogenation processes, it is important to note that the polymers to be hydrogenated in addition to the ethylenically unsaturated Double bonds also other reactive towards hydrogenation functionalities can have. As a rule, the hydrogenation process should have a high selectivity with regard to of the double bonds to be hydrogenated. Furthermore, the Basically, hydrogenation the risk that reactive intermediates are generated on the polymer be those with unreacted double bonds with crosslinking can react.

method for the hydrogenation of polymers, the ethylenically unsaturated double bonds have, are fundamentally known. An overview of such Methods give N. T. McManus et al. (J. Macromol. Sci., Rev. Macromol. Chem. Phys. 1995, C35 (2), 239-285). All of the described methods have in common that the implementation is carried out in an organic medium. Usually will however, gelation was observed during hydrogenation, indicating crosslinking reactions points.

From the EP-A 588 097 the hydrogenation of polymers based on butadiene / acrylonitrile is known. The polymers are reacted as aqueous dispersions in at least five times the amount, based on the dispersion, of an organic solvent in the presence of ruthenium catalysts. The disadvantage of this process is the use of large amounts of solvent.

US-A 3,898,208 discloses a process for hydrogenating a polymer having ethylenically unsaturated double bonds in an organic solvent as a swelling agent in the presence of a rhodium catalyst.

N. K. Singha et al. describe in Rubber Chemistry and Technology 1995, 68, 281-286 a process for the hydrogenation of aqueous NBR latex in the presence of a rhodium catalyst with sulfonated triphenylphosphine ligands.

EP-B 1 036 098 describes a process for the hydrogenation of aqueous polymer dispersions containing butadiene in the presence of a ruthenium catalyst and at least one phosphorus-containing compound. WO 00/73357 discloses an analogous process in which rhodium and ruthenium compounds with phosphorus-containing components are used as hydrogenation catalysts. A disadvantage of both processes is that they are batch processes. Discontinuous processes that are operated at high pressure are uneconomical due to the very long cycle times.

It there was therefore the task of an alternative method for selective Hydrogenation of ethylenically unsaturated To find double bonds in polymers.

The Task was solved by a process for the selective hydrogenation of ethylenically unsaturated Double bonds in polymers P with hydrogen in the presence at least one hydrogenation catalyst in which the reaction is carried out continuously performs.

These are preferably aqueous dispersions of polymers P in which the selective Hy Drying of ethylenically unsaturated double bonds will be carried out by the inventive method.

On continuous process in the sense of the invention stands out in that the same amount of aqueous dispersion of the hydrogenation device supplied as removed becomes. The arrival and departure times are of course excluded corresponding to the residence time of the dispersion in the hydrogenation device.

The execution the hydrogenation according to the invention usually takes place in such a way that first the hydrogenation catalyst into the aqueous dispersion according to one of the options described below of the polymer P incorporated. If necessary, the dispersion is made by dilution with water or a water-emulsifier mixture or with one Water-miscible organic solvents to a suitable solids content.

Suitable solvents for dilution include, in particular, C ₁ -C ₄ -alkanols such as, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol and tert-butanol, and also toluene, ketones such as acetone and ethyl methyl ketone, cyclic Ethers such as tetrahydrofuran or dioxane or amides such as N, N-dimethylformamide or N-methylpyrrolidone.

The Solvent content the aqueous to be hydrogenated Dispersion is usually in the case of ruthenium-containing catalysts not more than 20% by weight based on the total weight of the dispersion. Preferably is the solvent content not more than 15% by weight, preferably not more than 10% by weight, particularly preferably not more than 5% by weight, and very particularly preferably not more than 1% by weight based on the total weight of the dispersion.

at The use of rhodium-containing catalysts has a solvent content usually less than 5% by weight, preferably less than 2.5% by weight, particularly preferably less than 1% by weight and very particularly preferably less than 0.1% by weight, based on the total weight of the dispersion.

In particular contains the watery Dispersion does not contain any organic solvent.

The Solids content of the polymer P dispersion to be hydrogenated is usually in the range of 10 to 60 wt .-%, preferably in the range from 20 to 50% by weight, based on the total weight of the dispersion.

Then the optionally catalyst-containing dispersion is passed into a reaction vessel suitable for the hydrogenation ( 1 ).

Acting according to the invention it is a heatable reactor, taking suitable measures, z. B. agitation, circulation or gas circulation, for good mixing is ensured. For example, it can a stirred reactor, a circulating gas reactor or a bubble column. Gas circulation reactors are preferred or bubble column. If multiple reactors are used, e.g. B. two to four, so can these can be arranged in a cascade. With a reactor cascade the hydrogen used for the hydrogenation in the first of the Reactors or in all reactors of the cascade. Prefers the hydrogen is fed into the first reactor.

The According to the invention, the dispersion to be hydrogenated is fed continuously in the first heatable reactor by means of a pump system, for example a high pressure pump.

In a preferred embodiment of the method according to the invention the at least one heatable reactor is followed by a post-reactor. Subsequently the exhaust gas is separated off, for example by means of a high-pressure separator, before the hydrogenated dispersion is let down.

It is often appropriate, the Reactors beforehand with an inert gas, for example nitrogen, to wash.

The hydrogenation is generally carried out at a partial pressure of hydrogen in the range from 0.5 to 600 bar, preferably 50 to 400 bar, in particular 100 to 300 bar. The reaction temperature is generally in the range from 20 to 250 ° C., preferably 50 to 200 ° C., in particular 100 to 180 ° C. Depending on the type of catalyst system and the desired conversion, amounts of catalyst are in the range from 1 to 1000 ppm Ruthenium and / or rhodium, based on the total weight of the polymer dispersion to be hydrogenated, preferably 5 to 500 ppm. The residence time is generally in the range from 1 to 30 hours, preferably 2 to 25 hours and in particular 3 to 20 hours.

Depending on the desired property of the hydrogenated polymer, the reaction can be carried out up to a certain conversion, which can be adjusted in a known manner by selecting the reaction parameters such as hydrogen pressure and temperature, type and amount of the catalyst system used and residence time. The reaction is preferably carried out up to a conversion of at least 50%, based on the ethylenically unsaturated double bonds contained in P. A conversion can be determined, for example, by IR spectroscopy by checking the bands in the range from 900 to 1000 cm ^{−1, which} are typical for ethylenically unsaturated double bonds.

The inventive method is characterized by the fact that the ethylenic double bonds the polymers P also in the presence of other hydrogenation-active double bonds, for example aromatic C = C double bonds, carbonyl groups, Nitrile functions etc., are selectively hydrogenated without any noticeable Hydrogenation of other double bonds is observed. It is ≤ 2%, preferably ≤ 1% and particularly preferably ≤ 0.5 %, for example between 0.1 and ≤ 0.5%, based on the number on double bonds in the polymer P, other double bonds in the polymer P is hydrogenated.

The execution the hydrogenation according to the invention usually takes place in such a way that one of the catalysts mentioned below or catalyst precursors and at least one or more coligands, for example the phosphorus-containing compounds mentioned below, if appropriate solved in an organic solvent, to the polymer dispersion.

In a preferred embodiment of the method according to the invention the hydrogenation catalyst without the addition of an organic solvent incorporated into the dispersion of the polymer P to be hydrogenated. For this purpose, the hydrogenation catalyst as such, i.e. H. in Form of a complex compound that the respective transition metal and at least contains a phosphorus-containing compound as ligand in the dispersion be incorporated. In this case, familiarization takes place in usually by adding the complex compound from transition metal and Coligand, preferably from the group of phosphorus-containing compounds, into the watery Dispersion of the polymer to be hydrogenated P. The complex compound made of transition metal and phosphorus-containing compound as a solid, as an aqueous solution or as a solution in an organic solvent be added.

you can the transition metal and the phosphorus-containing compound also separately in the dispersion of incorporate polymers P to be hydrogenated. Works for this purpose one the transition metal in the form of a salt or a complex compound that does not contain phosphorus Compound comprises, in the dispersion of the polymer P. The phosphorus Connection is here as a separate connection in the dispersion of Polymers P incorporated.

to Incorporation of the transition metal For example, a salt can be added to the dispersion of the polymer P. or a suitable complex compound of the transition metal as a solid or as a solution in water or in an organic solvent to the dispersion of the polymer P.

In a preferred embodiment of the method according to the invention the transition metal is incorporated so that before the preparation of the dispersion of the polymer P a salt or a complex compound of the transition metal in those to be polymerized Monomers M dissolves and then that Polymer P by polymerizing the monomers M in the presence of the transition metal manufactures. This method is particularly useful if the production of the aqueous Dispersion of the polymer P by radical aqueous emulsion polymerization of the monomers M forming the polymer P. Unless it is the watery Dispersion of the polymer P is a secondary dispersion, the transition metal in a suitable form in a solution or melt the polymer, which then into the actual watery Dispersion of the polymer P is transferred. The phosphorus-containing compound can in principle be added to any of the above mentioned times are added. They are preferably given phosphorus-containing compound to the aqueous dispersion of the polymer P. In particular, they are added to the shortly before the hydrogenation aqueous Dispersion of the polymer P.

Examples of salts and complex compounds of rhodium and ruthenium which are suitable according to the invention and which do not yet contain any phosphorus-containing compound as ligands are listed below: The salts of ruthenium and rhodium include their hydrides, oxides, sulfides, nitrates, sulfates, Ha logenide, e.g. B. their chlorides, carboxylates, e.g. B. their acetates, propionates, ethylhexanoates or benzoates, their salts with sulfonic acids and mixed salts, ie salts with different anions, for. B. the oxide chlorides. Also suitable are salts of complex ions of rhodium and / or ruthenium, for example the salts of rhodium or of ruthenium oxygen acids, the salts of halogenoruthenates and halogenorhodates, in particular the chlororuthenates and chlororhodates, the amine and aquo complexes of the rhodium halides and the ruthenium halides, in particular the chlorides, as well as the salts of nitroruthenates. Examples of the aforementioned salts and complex salts are: ruthenium (III) chloride, ruthenium (III) nitrosyl chloride, ammonium pentachloroaquoruthenate (III), hexamminruthenium (II) and ruthenium (III) chloride, dichlorobis (2,2'-dipyridyl) ruthenium (II), tris (2,2'-dipyridyl) ruthenium (II) chloride, pentammine chlororuthenium (III) chloride, potassium pentachloronitrosylruthenium (II), ruthenium (IV) oxide, tetraacetochlorodiruthenium (II, III), hexakisacetate triaquo-μ-oxotrirutium (III) acetate, rhodium (III) chloride, rhodium (III) hydroxide, rhodium (III) nitrate, rhodium (III) sulfate, ammonium pentachloroaquorhodate (III), potassium pentachlororhodate (III), sodium hexachlororhodate (III), triammine trichlororhodium (III), trisethylene diamine (III) chloride, rhodium (II) acetate dimer, hexakisacetatotriaquo-μ-oxotrisrhodium (III), rhodium (III) hydroxide, rhodium (IV) oxide and potassium hexanitrorhodate (III). Neutral complexes of rhodium and ruthenium are also suitable. It should be noted here that the transitions between salts of ruthenium or rhodium as well as salt-like and neutral complexes are fluid and the classification here is only of an orderly nature. Examples of neutral complexes which contain no phosphorus-containing compound are the 2,4-pentanedionates of rhodium and ruthenium such as ruthenium (III) tris-2,4-pentanedionate, rhodium (I) dicarbonyl-2,4-pentanedionate, rhodium ( III) tris-2,4-pentanedionate, bisethylenrhodium (I) -2,4-pentanedionate and norbornadienrhodium (I) -2,4-pentanedionate, the carbonyl complexes of ruthenium and rhodium such as dodecacarbonyltetrarhodium, hexadecacarbonylrhodium, tetracarbonirdi-μ (chloro I) and dodecacarbonyl triruthenium.

Suitable according to the invention are organic, phosphorus-containing compounds, in which the phosphorus atoms are trivalent. They preferably contain one or two phosphorus atoms.

Examples of preferred phosphorus-containing compounds are the compounds of the general formula I. PR ₃ (I) and the compounds of formula II R ₂ P- (O) _x -A- (O) _y -PR ₂ (II) wherein
R may be the same or different and independently of one another C ₁ -C ₁₀ alkyl, C ₄ -C _{1 2} cycloalkyl, aryl, C ₁ -C ₁₀ alkyloxy, C ₄ -C _{1 2} -cycloalkyloxy and aryloxy or fluorine, or two radicals R together are C ₃ -C ₆ alkylene, C ₃ -C ₆ alkenylene or C ₃ -C ₆ alkadienylene,
A represents a bivalent hydrocarbon radical,
x, y independently of one another stand for 0 or 1, and preferably stand for 0,
P phosphorus and
O is oxygen.

In this context, C ₁ -C ₁₀ alkyl is both linear and branched alkyl which has 1 to 10, preferably 1 to 6 and in particular 1 to 4 carbon atoms, for. B. methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl, n-hexyl, 2-ethylhexyl and n-decyl. C ₁ -C ₁₀ alkyloxy represents a linear or branched, primary, secondary or tertiary alkoxy group having 1 to 10, preferably 1 to 6 and in particular 1 to 4 carbon atoms, for. B. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, 2-butyloxy, tert-butoxy, n-hexyloxy, 2-ethylhexyloxy. The alkyl groups in C ₁ -C ₁₀ alkyl and C ₁ -C ₁₀ alkyloxy can be partially or completely halogenated and / or have one, two or three functional groups, selected from hydroxy or amino functions, or by one or more, not adjacent Oxygen atoms or imino groups can be interrupted. Examples of such radicals are 2-hydroxyethyl, hydroxypropyl, 2-aminoethyl, 5-hydroxy-3-oxopentyl. Here and below, partially halogenated means that the respective group has one, two, three, four or five halogen atoms, preferably chlorine or fluorine.

C ₄ -C _{1 2} cycloalkyl represents saturated mono-, bi- and tricyclic compounds such as cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, camphyl or tricyclodecanyl, which may have up to 12 carbon atoms and which may be partially fully halogenated or and / or one, two or three substituents as functional groups, selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, hydroxy or amino functions. They can also have one or more non-adjacent oxygen atoms or imino groups in the cycle.

If two radicals R together represent C ₃ -C ₆ alkylene, C ₃ -C ₆ alkenylene or C ₃ -C ₆ alkadienylene, they mean a linear carbon chain with 3, 4, 5 or 6 carbon atoms in the chain, where this can be interrupted by one or two oxygen atoms. Thus, together with the phosphorus atom to which they are attached, they form a phosphorus heterocycle which, in addition to the phosphorus atom, can also have one or two oxygen atoms and has at least 4 to 9 ring atoms. C ₃ -C ₆ alkylene, C ₃ -C ₆ alkenylene or C ₃ -C ₆ alkadienylene can be either one, two or three substituents or functional groups, selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ - Alkoxy, hydroxy or amino functions. You can also form a condensed polycycle with one or two phenyl groups. For example, two radicals R can form a tetrahydrophosphol-1-yl, benzodihydrophosphol-1-yl, dibenzophosphol-1-yl or a phenoxaphosphan-10-yl radical.

Aryl stands for a mono- to polynuclear aromatic ring system, preferably for a mono- to trinuclear aromatic ring system containing 6 to 14 carbon ring members, e.g. B. phenyl, naphthyl or anthracenyl, which may be partially or completely halogenated and / or one or more substituents selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ alkyloxy, amino, di-C ₁ -C ₄ alkylamino and hydroxy, which may optionally also be ethoxylated. Preferred aryl is phenyl, o-, m- or p-tolyl, p-chlorophenyl, p-tert-butylphenyl and p-hydroxyphenyl, which can also be ethoxylated (EO grade 1 to 50). Alkylaryl, such as benzyl, is also possible.

A stands for a saturated or unsaturated, monocyclic, polycyclic or acyclic, divalent hydrocarbon radical with preferably up to 25 carbon atoms.

A is, for example linear or branched C ₂ -C _{1 2} -, C ₃ -C ₆ alkylene, preferably as 1,2-ethylene, 1,2- or 1,3-propylene, 2,3-butylene, 2, 2-dimethyl-1,3-propylene, butyn-1,4-diyl, which is optionally substituted and / or is part of a carbocycle or a heterocycle, e.g. B. as in 2,3- (1 ', 3'-dioxa-2', 2'-dimethylpropan-1 ', 3'-diyl) butane-1,4-diyl and trans- or cis-norbornane-1, 2-diyl. A also stands for divalent mono-, bi- or tricyclic radicals with phenyl, naphthyl or anthracenyl groups and includes in particular o-phenylene, o, o-diphenylene, (o, o-diphenylene) methane, 2,2- (o , o-diphenylene) propane, (o, o-diphenylene) ether, 1,8-naphthylene, 2,2'-binaphthylene, 1,1'-ferrocenylene, 1,9-anthracenylene, 1,9-xanthenylene, where the Phenylene, naphthylene or anthracenylene groups can be partially or completely halogenated and / or one or more substituents selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ alkyloxy, amino, di-C ₁ -C ₄ alkylamino and hydroxy, which can optionally also be ethoxylated.

preferred Radicals R are methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, Isobutyl, tert-butyl, n-hexyl, cyclohexyl, cyclopentyl, phenyl, o-, m- or p-tolyl, p-chlorophenyl, p-tert-butylphenyl and p-hydroxyphenyl, in particular n-butyl, 2-butyl, isobutyl, tert-butyl, cyclohexyl and phenyl.

Prefers the radicals R have the same meaning.

Examples for preferred Compounds of the formula I are triphenylphosphine, triisopropylphosphine, tri-n-butylphosphine, Tri-n-octylphosphine, tricyclopentylphosphine, tricyclohexylphosphine, Trisanisylphosphine, tris (p-tolyl) phosphine, triethylphosphite, tri-n-butylphosphite and Dibenzophosphole. examples for preferred compounds of formula II are 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,1'-bis (diphenylphosphino) ferrocene, 2,2'-bis (diphenylphosphino) -1,1'-biphenyl and 2,2'-bis (diphenylphosphino) -1,1'-naphthyl. Further example for Compounds of the general formula II can be found in WO 97/33854, Angew. Chem. 1999, 111, p. 349 and in Applied Homogeneous Catalysis with Organometallic Compounds, Vol. 1 (ed., B. Cornils, W. A. Herrman), VCH Weinheim, New York 1996.

The phosphorus-containing according to the invention Connections can also be modified in such a way that they have more for coordination atoms or atomic groups suitable with the metal atom, such as amino or Imino groups, e.g. B. oxazilone and imidazoline groups. Preferred phosphorus-containing compounds are those mentioned above Compounds of the general formula I and II.

Complexes of ruthenium with at least one phosphorus-containing compound preferably obey the general formula III: RuX ¹ X ² (CO) _k (L ¹ ) _l (L ² ) ₂ (III) wherein
X ¹ ; X ² independently of one another for hydrogen, halogen, preferably chloride, the anion of a carboxylic acid, for. B. acetate, benzoate or ethylhexanoate or a sulfonic acid, e.g. B. phenyl sulfonate, acetylacetonate, phenyl, which is optionally substituted,
k; l independently of one another represent 0, 1 or 2, with the proviso that k + l = 1 or 2,
L ^{1 is} selected from carbonyl, pyridine, benzonitrile, dibenzophosphole, cycloolefins and a ligand of the general formula PR ₃ , in which R has the meanings given above, and
L ^{2 stands} for a phosphorus-containing ligand of the formula I and (L ² ) _{2 can} also stand for a phosphorus-containing ligand of the formula II.

Complexes of rhodium with at least one phosphorus-containing compound preferably obey the general formula IV: RhX _m L ³ L ⁴ (L ⁵ ) _n (IV) wherein
X represents halide, preferably chloride or bromide, the anion of a carboxylic acid, acetylacetonate, aryl or alkyl sulfonate, hydride or the diphenyltriazine anion,
L ³ , L ⁴ , L ⁵ independently of one another for CO, olefins, cycloolefins, benzonitrile, a phosphorus-containing ligand of the formula I or II,
m represents 1 or 2 and n represents 0, 1 or 2,
with the proviso that at least one of the ligands L ³ , L ⁴ and L ^{5 represents} one of the above-mentioned phosphorus-containing ligands of the general formula I or II.

X in formula III or IV preferably represents hydride, chloride, bromide, Acetate, tosylate, acetylacetonate or the diphenyltriacine anion, in particular for hydride, Chloride, acetate or acetylacetonate.

Examples for suitable Phosphine complexes of the general formulas III and IV are: carbonylchlorohydridobis (tricyclohexylphosphine) ruthenium (II), Carbonylchlorohydridobis (triisopropylphosphine) ruthenium (II), carbonylchlorohydridobis (triphenylphosphine) ruthenium (II), Carbonylchlorostyrylbis (tricyclohexylphosphine) ruthenium (II), carbonylchlorostyrylbis (triisopropylphosphine) ruthenium (II), Carbonylchlorobenzoatobis (triphenylphosphine) ruthenium (II), dichlorotris (triphenylphosphine) ruthenium (II), Bis (triphenylphosphine) ruthenium dicarbonyl chloride, acetateohydridotris (triphenylphosphine) ruthenium (II), Chlorotris (triphenylphosphine) rhodium (I), hydridotetrakis (triphenylphosphine) rhodium (I), Hydridotris (dibenzophosphole) rhodium (I).

Preferred transition metal in the method according to the invention is ruthenium. Ruthenium is preferred as one of the above Ruthenium compounds with 2,4-pentanedionate ligands are used. In particular ruthenium tris-2,4-pentanedionate is used on. Ruthenium is preferably used with compounds of the formula I in particular with triisopropylphosphine, tri-n-butylphosphine, tris-n-octylphosphine, Tricyclohexylphosphine, triphenylphosphine, trisanisylphosphine and Tris (p-tolyl) phosphine.

ever amounts of catalyst depend on the type of catalyst system and the desired conversion in the range of 1 to 1000 ppm, preferably 5 to 500 ppm of ruthenium and / or rhodium, based on the total weight of the hydrogenated Polymers P used. The molar ratio of phosphorus Connection to metal atom is usually in the range of 1:10 to 100: 1, preferably 1: 2 to 50: 1 and especially 1: 1 to 20: 1.

The Incorporation of the hydrogenation catalyst into the dispersion of the hydrogenation Polymers P can, as described, both without and with additives an organic solvent respectively.

As Substrates for the hydrogenation process according to the invention basically come all watery Dispersions of polymers P with ethylenically unsaturated Double bonds into consideration. The dispersion particles have in the Usually a particle size of 40 to 500 nm, preferably from 60 to 250 nm and particularly preferred from 70 to 220 nm. These include both dispersions by radical polymerization of aqueous Monomer emulsions of the monomers M are prepared (primary dispersions), as well as those whose polymers are produced in a different way and then in a watery Dispersion are transferred (Secondary dispersions). The term polymer dispersion basically also includes dispersions of Microcapsules.

Suitable polymers P which contain ethylenically unsaturated double bonds are homo- or copolymers of conjugated dienes which generally contain 10 to 100% by weight of at least one conjugated diene as monomer (a). Suitable diene monomers (a) include, for example, butadiene, isoprene, chloroprene, 1-methylbutadiene, 2,3-dimethylbutadiene, 2- (tri-C ₁ -C ₄ -alkyl) silylbutadiene, such as 2-triethylsilyl-1,3-butadiene , and their mixtures. Preferred monomers (a) are butadiene and isoprene, especially butadiene.

In a preferred embodiment is the inventive method for the Hydrogenation of polymers P used, consisting of at least one conjugated diene as monomer (a) and at least one other, are built up with the diene copolymerizable monomer (b). such Copolymers are usually from 10 to 99 wt .-%, in particular 20 to 95% by weight of monomers (a) and 1 to 90% by weight, preferably 5 to 80 wt .-% monomers (b) built.

Suitable monomers (b) are, for example, olefins, e.g. B. ethylene, propylene, vinyl aromatic monomers, e.g. B. styrene, α-methylstyrene, o-chlorostyrene or vinyltoluenes, vinyl esters of aliphatic or branched C ₁ -C ₁₈ monocarboxylic acids such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl hexanoate, vinyl 2-ethylhexanoate, vinyl decanoate, vinyl laurate and vinyl stearate, esters preferably 3 to 6 carbon atom-containing ethylenically unsaturated mono- and dicarboxylic acids, such as in particular acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with generally 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms, such as , B. methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, n-hexanol, 2-ethylhexanol, or C ₅ -C ₁₀ cycloalkanols such as cyclopentanol or cyclohexanol and especially among them preferably the esters of acrylic acid and / or methacrylic acid, e.g. B. methyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate and tert-butyl acrylate. Other suitable monomers (b) are ethylenically unsaturated nitriles such as acrylonitrile or methacrylonitrile. Preferred monomers (b) are styrene, α-methylstyrene and acrylonitrile.

Next the monomers (a) and (b) the polymers P to be hydrogenated also modifying monomers (c) contained in copolymerized form. The polymers P can in usually up to 20 wt .-%, based on the total weight of the monomers (a), (b) and (c), such modifying monomers (c) polymerized contain. Modifying monomers (c) include monomers (c ') which has increased water solubility (e.g.> 60 g / l at 25 ° C and 1 bar). The monomers (c ') include e.g. B. the aforementioned ethylenic unsaturated Carboxylic acids, especially acrylic acid, methacrylic acid, maleic acid, itaconic, the amides of the aforementioned ethylenically unsaturated carboxylic acids, e.g. B. acrylamide and methacrylamide, the N-alkylolamides of the aforementioned ethylenically unsaturated carboxylic acids such as N-methylolacrylamide and N-methylol methacrylamide, the hydroxyalkyl esters of the aforementioned ethylenically unsaturated Carboxylic acids, e.g. B. 2-hydroxyethyl acrylate and methacrylate, ethylenically unsaturated sulfonic acids or whose alkali metal salts, e.g. B. vinyl sulfonic acid, allylsulfonic acid, methallylsulfonic acid, acrylamido-2-methylpropanesulfonic acid, further N-vinyl lactams, e.g. B. N-vinyl pyrrolidone or N-vinyl caprolactam. Such monomers (c ') are usually to a lesser extent, d. h <20% by weight, based on the total amount of the monomers (a) to be polymerized, (b) and (c), preferably ≤ 10 % By weight, for example in amounts of up to 0.1 to 10% by weight and especially 0.5 to 8% by weight.

Farther the monomers (c) also comprise monomers (c ″), the at least two non-conjugated, ethylenically unsaturated bonds have, e.g. B. the diesters of dihydric alcohols with ethylenic unsaturated Monocarboxylic acids. Examples of this are alkylene glycol diacrylates and dimethacrylates such as ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, Propylene glycol di (meth) acrylate, further divinylbenzene, vinyl methacrylate, Vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, Diallyl phthalate, methylenebisacrylamide, cyclopentadienyl acrylate and methacrylate, tricyclodecenyl acrylate and methacrylate, N, N'-divinylimidazolin-2-one or triallyl cyanurate. Such monomers are, if desired, in Amounts of 0.01 to 10 wt .-%, based on the total amount of monomers (a) + (b) + (c) used.

The Advantages of the method according to the invention come especially in the hydrogenation of polymer dispersions to carry, which contain monomers (b) and / or (c) copolymerized, which have functional groups, which are basically one Hydrogenation accessible are. Which includes in particular monomers with carbonyl groups, nitrile groups and / or Aryl groups, e.g. B. phenyl groups, which are optionally also substituted could be.

Preferred embodiments of the process according to the invention relate to the hydrogenation of polymer dispersions, the polymers P of which essentially consist of butadiene and / or isoprene, in particular butadiene as the sole monomer (a), and of styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, isobutene and / or (meth) acrylic acid alkyl esters are built up as monomers (b).

preferred Monomer combinations (a) / (b) include butadiene and / or isoprene Styrene and / or α-methylstyrene, Butadiene with acrylonitrile and / or methacrylonitrile, butadiene and Isoprene with acrylonitrile and / or methacrylonitrile; Butadiene with acrylonitrile and styrene; Butadiene with isobutene; Butadiene with (meth) acrylic acid alkyl esters.

• – 20 bis 95 Gew.-% Monomeren (a), ausgewählt unter Butadien und Isopren, und
• – 5 bis 80 Gew.-% Monomeren (b), ausgewählt unter Styrol, α-Methylstyrol und Acrylnitril,

wobei die Anteile der Monomere (a) und (b) sich zu 100 Gew.-% addieren. Selbstverständlich können derartige Polymerisate modifizierende Monomere (c) in den oben bezeichneten Mengen einpolymerisiert enthalten, und zwar vorzugsweise in Mengen bis zu 10 Gew.-%, bezogen auf die Gesamtmenge der Monomere (a), (b) und (c). Bevorzugte Monomere (c) sind Acrylsäure, Methacrylsäure, Itaconsäure, Acrylamid, Methacrylamid, N-Methylolacrylamid und/oder N-Methylolmethacrylamid.A special embodiment of the present invention relates to the hydrogenation of polymer dispersions, the polymers P of which are essentially composed of

• - 20 to 95 wt .-% monomers (a) selected from butadiene and isoprene, and
• 5 to 80% by weight of monomers (b) selected from styrene, α-methylstyrene and acrylonitrile,

the proportions of the monomers (a) and (b) add up to 100% by weight. Such polymers can of course contain copolymerized modifying monomers (c) in the above-mentioned amounts, preferably in amounts of up to 10% by weight, based on the total amount of monomers (a), (b) and (c). Preferred monomers (c) are acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, N-methylolacrylamide and / or N-methylolmethacrylamide.

• – 30 bis 70 Gew.-% Butadien,
• – 30 bis 70 Gew.-% Styrol und
• – 0,1 bis 5 Gew.-% Acrylsäure,

wobei die Anteile der Monomere (a), (b) und (c) sich zu 100 Gew.-% addieren.A preferred monomer composition of monomers (a), (b) and (c) contains

• 30 to 70% by weight of butadiene,
• - 30 to 70 wt .-% styrene and
• 0.1 to 5% by weight of acrylic acid,

the proportions of the monomers (a), (b) and (c) add up to 100% by weight.

The The preparation of such polymers P is known to the person skilled in the art and can basically by anionic, radical or Ziegler-Natta polymerization in solution, be carried out in bulk, in suspension or in emulsion. Depending on the type of reaction, the conjugated dienes are 1,4-polymerized and / or 1,2-polymerized before. For the hydrogenation process according to the invention polymers are preferably used which are characterized by radical, aqueous Emulsion polymerization of the aforementioned monomers (a) and optionally (b) and / or (c) (including Mini and micro emulsion polymerization) were produced. This procedure are well known to the person skilled in the art and are described in detail in the literature, for example in Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., Vol. A21., Pp. 373-393. As a rule, such polymers are in the presence of radical initiators and optionally surface-active Substances such as emulsifiers and protective colloids (see for example Houben-Weyl, Methods of Organic Chemistry, Vol. XIV / 1, Macromolecular Fabrics, Georg Thieme-Verlag, Stuttgart 1961, pp. 192-208) carried out.

suitable radical polymerization initiators include organic peroxides such as tert-butyl hydroperoxide, benzoyl hydroperoxide, diisopropylbenzoyl peroxide, inorganic peroxides, such as hydrogen peroxide, salts of the peroxomono- and / or peroxodisulfuric acid, in particular the ammonium and / or alkali metal peroxydisulfates (Persulfates), as well as azo compounds, the persulfates especially are preferred. Combined systems consisting of at least one organic reducing agent and at least one Peroxide and / or hydroperoxide are composed, e.g. B. tert-butyl hydroperoxide and the sodium salt of hydroxymethanesulfinic acid or hydrogen peroxide and ascorbic acid (as an electrolyte-free redox initiator system), and combined systems, the one above also a small amount of one soluble in the polymerization medium Metal compound, its metallic component in several valence levels can occur contain, e.g. B. ascorbic acid / iron (II) sulfate / hydrogen peroxide, being instead of ascorbic acid too frequently the sodium salt of hydroxymethanesulfinic acid, sodium sulfite, sodium bisulfite or sodium bisulfite and instead of hydrogen peroxide also tert-butyl hydroperoxide, Alkali metal peroxide sulfates and / or ammonium peroxidisulfate are used can be. Instead of a water soluble Iron (II) salt can also be a combination of water-soluble FeN salts are used.

The the polymerization initiators mentioned are used in customary amounts, z. B. in amounts of 0.01 to 5, preferably 0.1 to 2.0 wt .-%, based on the monomers to be polymerized.

Optionally, the monomer mixture in the presence of conventional polymerization regulators such as mercaptans, e.g. B. tert-dodecyl mercaptan, terpenols or Co (II) complexes are polymerized. Other controller systems that are used in the method according to the invention are described in the older German patent application with the file number 10256617.8 and in the prior art cited therein. These are then ver in an amount of 0.01 to 5 wt .-%, based on the total amount of the mixture applies.

There are no particular restrictions with regard to the emulsifiers that can be used. Neutral emulsifiers such as ethoxylated mono-, di- and tri-alkylphenols (EO grade: 3 to 50, alkyl radical: C ₄ to C ₉ ) or ethoxylated fatty alcohols (EO degree: 3 to 50, alkyl radical C ₈ to C ₃₆ ) are preferred ) and / or anionic emulsifiers such as the alkali and ammonium salts of fatty acids (alkyl radical: C _{1 2} to C ₂₄ ), alkyl sulfates (alkyl radical: C ₈ to C ₂₂ ), of sulfuric acid semiesters of ethoxylated alkanols (EO degree: 4 to 30, alkyl radical : C ₈ to C ₂₂ ) and ethoxylated alkylphenols (EO grade: 3 to 50, alkyl radical: C ₄ to C ₁₀ ), of alkylsulfonic acids (alkyl radical: C ₈ to C ₂₂ ) and of alkylarylsulfonic acids (alkyl radical: C ₄ to C ₁₈ ). Other suitable anionic emulsifiers are alkali metal or ammonium salts of mono- or di-C ₄ -C ₂₄ -alkyl derivatives of bis (phenylsulfonic acid) ether, e.g. B. technical mixtures containing 50 to 80 of the monoalkylated product. Such emulsifiers are from the US-A 4,269,749 known, the technical mixtures are commercially available for example under the name Dowfax ^® 2A1 (Dow Chemical).

Particularly preferred are the alkali metal and / or ammonium salts, especially the sodium salts of alkylarylsulfonic acids, alkylsulfonic acids (e.g. sulfonated C _{1 2} -C _{1 8} paraffin; commercially available as emulsifier K30 from Bayer AG), alkyl sulfates (e.g. Sodium lauryl sulfonate as Texapon ^® K12 from Henkel KGaA) and from the sulfuric acid half-esters of ethoxylated alkanols (e.g. sulfated ethoxylate of lauryl alcohol with 2 to 3 EO units; as Texapon ^® NSO from Henkel KGaA on the market). Also suitable emulsifiers are the sodium or potassium salts of fatty acids (C _{1 2} -C ₂₃ alkyl radicals), e.g. B. Potassium oleate. Further suitable emulsifiers can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme Verlag, Stuttgart, 1961, pages 192 to 208. Instead of or in a mixture with emulsifiers, conventional protective colloids such as Polyvinyl alcohol, polyvinyl pyrrolidone or amphiphilic block polymers with short hydrophobic blocks can be used for co-stabilization. As a rule, the amount of emulsifiers used, based on the monomers to be polymerized, will not exceed 5% by weight.

The radical polymerization reaction can in overall approach (Batch process) carried out are, but preferably, especially on an industrial scale, after the feed process worked. Here the predominant Amount (usually 50 to 100 wt .-%) of the monomers to be polymerized the polymerization vessel according to the progress the polymerization of those already in the polymerization vessel Monomers added. The radical initiator system can do this both completely placed in the polymerization vessel, as well as according to its consumption in the course of the radical aqueous emulsion polymerization be fed continuously or stepwise to the polymerization reaction. In particular depends this in a known manner both from the chemical nature of the initiator system as well as from the polymerization temperature. Preferably the initiator system according to the Consumption fed to the polymerization zone.

The polymerization reaction is preferably carried out in the presence of an aqueous polymer dispersion as polymer seed (seed latex). Such methods are known in principle to the person skilled in the art and for example in DE-A 42 13 967 . DE-A 42 13 968 . EP-A 567 811 . EP-A 567 812 or EP-A 567 819 to which reference is hereby made in full. In principle, depending on the desired property, the seeds can be introduced or added continuously or in stages during the polymerization. The polymerization is preferably carried out with the seed placed in front. The amount of seed polymer is preferably in the range from 0.05 to 5% by weight, preferably 0.1 to 2% by weight and in particular 0.2 to 1% by weight, based on the monomers (a) to ( c). The polymer particles of the seed latex used preferably have weight-average particle diameters in the range from 10 to 100 nm, preferably 20 to 60 nm and in particular approximately 30 nm. Polystyrene seed is preferably used.

The The polymerization reaction is preferably carried out under pressure. The The duration of the polymerization can vary within a wide range. she is generally in the range of 1 to 15 hours, preferably in the range of 3 to 10 hours. Also the polymerization temperature is variable in a wide range. Depending on the initiator used, it is about 0 to 110 ° C.

The polymer dispersions prepared in this way generally have solids contents of up to 75% by weight. Polymer dispersions with solids contents of 40 to 70% by weight are of particular importance. The dispersions with these solids contents can be used for the hydrogenation process according to the invention. If necessary, however, the dispersions must first be diluted to a suitable solids content. The solids content of the dispersion used in the process is preferably in the range from 10 to 60% by weight, in particular 20 to 50% by weight, based on the total weight the dispersion.

The surface-active substances which are usually still present in the polymer dispersions and further substances which are used, for example, in emulsion polymerizations as customary polymerization auxiliaries do not have a disruptive effect in the hydrogenation process according to the invention. However, it is recommended to chemically or physically deodorize the polymer dispersions before the hydrogenation. Physical deodorization by stripping off the residual monomers using steam is known, for example, from US Pat EP-A 584 458 known. The EP-A 327 006 again, the use of conventional distillation processes is recommended. Chemical deodorization is preferably carried out by post-polymerization following the main polymerization. Such methods are for example in the DE-A 383 4734 , the EP-A 379 892 , the EP-A 327 006 , the DE-A 44 19 518 , the DE-A 44 35 422 as well as the DE-A 44 35 423 described.

A preferred embodiment of the present invention relates to the continuous hydrogenation process of the polymer based on butadiene / styrene. The hydrogenated polymers P 'which can be obtained are used in the EP-B 1 036 098 to which express reference is made here.

The by the method according to the invention available Polymers are characterized by a high, in comparison with the non-hydrogenated basic dispersions significantly improved stability against environmental influences such as Light, oxygen and / or increased Temperature off. This is predestined the hydrogenated polymers for use in outdoor applications, for example as a binder for Emulsion paints and coating compounds, as finishing for textiles, Leather and paper.

example

Preparation of a dispersion D1

5% monomer emulsion, 30 kg water and 3.5 kg seed latex (polystyrene seed, 30 nm, 33% by weight aqueous dispersion) were placed in a polymerization vessel and heated to 85.degree. To this was added 0.13 kg of sodium persulfate and heated to 95 ° C. for 15 minutes. Then, starting at the same time while maintaining the temperature, 10.51 kg of a 5% strength by weight aqueous sodium persulfate solution and the remaining amount of monomer emulsion were added over 4.5 hours via separate feeds, the pressure not exceeding 6 bar. The mixture was then polymerized for a further two hours while maintaining the temperature. The reaction mixture was then adjusted to 65 ° C., and 2.05 kg of a 10% strength by weight aqueous sodium hydroxide solution were then added. Then the residual monomer content was reduced to values <50 ppm by physical deodorization. monomer: 16 kg water 3.5 kg Dowfax ^® 2A1 (45% by weight aqueous solution) 1.3 kg acrylic acid 0.78 kg Sodium hydroxide solution (10% by weight aqueous solution) 18.2 kg styrene 0.005 kg Ruthenium triacetylacetonate

Continuous hydrogenation of dispersion D1 ( 2 ).

In the in 2 shown apparatus, the stirred reactors each have a liquid volume of 1.5 l, the post-reactor (tubular reactor without internals) has a liquid volume of 2.5 l.

8.4 l of the dispersion D1 with a solids content of 25% by weight, based on the total weight of the dispersion, were conveyed from a storage barrel into the storage container A. This container was covered with nitrogen. Then 0.34 g of tri-n-butylphosphine in 0.06 g of toluene was added and the mixture was stirred for 8 hours. The dispersion was then discharged into the buffer vessel B. From this container, 1 l / h of the dispersion was conveyed into the system via a high-pressure pump, so that the average residence time was 5.5 hours. The plant was operated at 150 ° C and 250 bar H ₂ . The hydrogen was metered directly into the first reactor at a rate of 500 standard l / h. The hydrogen was previously saturated with water by the hydrogen flow together with 90 ml of water per hour at 130 ° C heated pipe was passed. After the dispersion had passed through the plant, it was relaxed and the discharge was collected. Samples were regularly taken from the discharge and analyzed by means of IR spectroscopy. The turnover for a three-day operation of the plant averaged 50%.

Claims (15)

Process for the selective hydrogenation of ethylenically unsaturated double bonds in polymers P by reacting the polymers P with hydrogen in the presence of at least one hydrogenation catalyst, characterized in that the reaction is carried out continuously. A method according to claim 1, characterized in that the hydrogenation catalyst has at least one transition metal selected from Ruthenium and / or rhodium, and at least one containing phosphorus Compound that is a coordinative connection with the transition metal can train includes. Method according to one of the preceding claims, characterized characterized that you can implement at temperatures in the range from 20 to 250 ° C and hydrogen partial pressures in the range from 0.5 to 600 bar in an aqueous dispersion of the polymers P performs. Method according to one of the preceding claims, characterized characterized in that the content of organic solvents in the aqueous Dispersion of the polymers P when using ruthenium-containing Catalysts not more than 20 wt .-% and when using rhodium-containing Catalysts not more than 1 wt .-%, based on the total weight the dispersion. Method according to one of the preceding claims, characterized characterized that the transition metal is used as a salt and / or complex compound. Method according to one of the preceding claims, characterized in that the phosphorus-containing compound is selected from compounds of general formula I. PR ₃ (I) and compounds of formula II R ₂ P- (O) _x -A- (O) _y -PR ₂ (II) wherein R may be the same or different and independently of one another C ₁ -C ₁₀ alkyl, C ₄ -C _{1 2} cycloalkyl, aryl, C ₁ -C ₁₀ alkyloxy, C ₄ -C _{1 2} -cycloalkyloxy and aryloxy or fluoro are , or two radicals R together are C ₃ -C ₆ alkylene, C ₃ -C ₆ alkenylene or C ₃ -C ₆ alkadienylene, A is a bivalent hydrocarbon radical, x, y independently of one another are 0 or 1, P is phosphorus and O is oxygen. Method according to one of the preceding claims, characterized characterized that the transition metal Is ruthenium and the phosphorus-containing compound of the general Formula I corresponds. Method according to one of the preceding claims, characterized characterized in that 1 to 1000 ppm ruthenium and / or rhodium, based on the total weight of the dispersion. Method according to one of the preceding claims, characterized characterized that the watery Dispersion of the polymers P by radical, aqueous emulsion polymerization ethylenically unsaturated monomers M was manufactured. A method according to claim 9, characterized in that you have the transition metal in the form of a complex compound or a salt in those to be polymerized Monomers M dissolves or dispersed. Method according to one of claims 9 or 10, characterized in that the aqueous dispersion contains polymers P which consist of at least one conjugated diene as monomer (a) and at least one monomer (b) copolymerizable with the diene and optionally a modifying monomer (c) are set up. A method according to claim 11, characterized in that the polymers P are made up of 20 to 95% by weight Monomers (a) selected under butadiene and isoprene, and 5 to 80% by weight of monomers (b), selected under styrene, α-methylstyrene and acrylonitrile, where the proportions of monomers (a) and (b) add up to 100% by weight. A method according to claim 11, characterized in that the polymers P up to 20 wt .-%, based on the total amount of the monomers (a), (b) and (c), modifying monomers (c) in copolymerized form contain. A method according to claim 11 or 13, characterized in that the polymers P are made up of 30 to 70% by weight butadiene, 30 to 70 wt .-% styrene and 0.1 to 5% by weight Acrylic acid, in which the proportions of the monomers (a), (b) and (c) add up to 100% by weight. Use of the hydrogenation according to one of the preceding Expectations polymers obtained in outdoor applications, as a binder for Emulsion paints and coating compounds, as finishing for textiles, Leather and paper.