DE102004008198A1 - Simplified process for the production of impact-modified polystyrene - Google Patents

Abstract

A process for the preparation of impact polystyrene from diene monomers and styrene monomers by anionic polymerization, wherein DOLLAR A 1) in a first reactor of the diene monomers or from the diene monomers and styrene monomers, with an alkali metal organyl as an initiator and with the use of a solvent produces a rubber solution, and then DOLLAR A - an aluminum organyl or DOLLAR A - an aluminum organyl and a hybrid or organyl of an alkali metal DOLLAR A is added and then DOLLAR A 2) the resulting rubber solution in a second reactor, there DOLLAR A - styrene monomer and DOLLAR A - an organoaluminum or magnesium and DOLLAR A - adding a hybrid or organyl of an alkali metal initiator DOLLAR A, and polymerizing the resulting mixture, DOLLAR A, and allowing the rubber solution to transfer to the second reactor without first diluting it with styrenic monomer.

Description

• 1) in einem ersten Reaktor aus den Dienmonomeren, oder aus den Dienmonomeren und den Styrolmonomeren, mit einem Alkalimetallorganyl als Initiator und unter Mitverwendung eines Lösungsmittels, eine Kautschuklösung herstellt, und danach – ein Aluminiumorganyl, oder – ein Aluminiumorganyl und ein Hydrid oder Organyl eines Alkalimetalls, zufügt, und danach
• 2) die erhaltene Kautschuklösung in einen zweiten Reaktor überführt, dort – Styrolmonomer, und – ein Aluminiumorganyl oder Magnesiumorganyl, und – ein Hydrid oder Organyl eines Alkalimetalls als Initiator, zufügt, und die erhaltene Mischung polymerisiert,

und wobei man die Kautschuklösung in den zweiten Reaktor überführt, ohne sie zuvor mit Styrolmonomer zu verdünnen.The invention relates to a process for the preparation of impact-modified polystyrene from diene monomers and styrene monomers by anionic polymerization, wherein

• 1) in a first reactor from the diene monomers, or from the diene monomers and the styrenic monomers, with an alkali metal organyl as initiator and with the use of a solvent, produces a rubber solution, and thereafter - an aluminum organyl, or - an aluminum organyl and a hydride or organyl of an alkali metal , inflicts, and afterwards
• 2) the resulting rubber solution is transferred to a second reactor where it adds styrene monomer, and an organoaluminum or organomagnesium, and a hydride or organyl of an alkali metal initiator, and the resulting mixture is polymerized,

and transferring the rubber solution to the second reactor without first diluting it with styrene monomer.

The Invention also relates the impact polystyrene obtainable by the said process, the Use of the impact resistant Polystyrene for the production of moldings, films, fibers and foams, as well as the moldings, Foils, fibers and foams from the impact resistant Polystyrene.

Impact-resistant polystyrene (HIPS, High Impact Polystyrene) contains e.g. Polybutadiene rubber or styrene-butadiene block rubber, dispersed in a polystyrene hard matrix, and can be prepared by various polymerization methods be, for example by free-radical or anionic polymerization. The anionic polymerization of styrene and / or butadiene is for example in WO 98/07765 and WO 98/07766.

The obtained by anionic polymerization polymers have the radically obtained products have some advantages, et al lower residual monomer and oligomer contents. radical and anionic polymerization are fundamentally different. At the radical Polymerization proceeds the Reaction over free radicals and e.g. used peroxide initiators, whereas anionic polymerization proceeds via "living" carbanions and, for example Alkalimetallorganylverbindungen be used as initiators. The anionic polymerization tion is after consumption of the monomers preferably with a chain stopper, e.g. a protic substance like water or alcohols, broken off.

The anionic polymerization proceeds much faster and leads to higher revenues, as the radical polymerization. The temperature control of exothermic reaction is difficult due to the high speed. This can be achieved by using so-called retardants (such as Al, Zn or Mg organyl compounds), which reduce the reaction rate reduce. The viscosity the reaction mixture increases in anionic rubber production usually too fast, which can form undesirable "hot spots" in the reactor and the reaction mixture bad to handle. Therefore usually polymerized in an inert solvent, e.g. Hydrocarbons such as toluene or cyclohexane, and limited so the viscosity increase.

The obtained, usually batchwise prepared rubber solution is then usually stored in a buffer tank, and finally into a second, e.g. transferred continuously operated reactor, there with styrene monomer added and the mixture is polymerized to HIPS

In the prior art processes, for example WO 03/091296, as well as in the older, not pre-published Patent applications DE Az. 10250280.3 and DE Az. 10316266.6, is the rubber solution diluted in the first reactor with styrene to the solids content and the viscosity further lower and the solution easier to convert into the second reactor. However, through this styrene dilution the reactor sized larger are required as the actual rubber synthesis what the Construction and operating costs of the plant increased. In addition, the cycle time of the Synthesis of rubber, as the metered addition and mixing of the styrene a certain amount of time, the so-called dilution time, claimed. This increases the price of the end product HIPS.

Another disadvantage is that a rubber solution diluted with styrene is less storage-stable. in the In particular, unintentional polymerisation of the styrene ("runaway") must be prevented in the buffer tank by tempering the buffer tank in an elaborate manner and / or adding stabilizers to the stored rubber solution.

It The task was to remedy the disadvantages described. Especially the task consisted of an alternative process for the production of impact resistant Polystyrene provide that improved economy having. So should the process with a smaller rubber synthesis reactor get along.

In addition, should the process with regard to the cycle times in rubber synthesis be improved. After all should be the rubber solution can be stored more easily (between) than in the state of the art of the technique.

Accordingly, became the process defined at the outset, the impact polystyrene mentioned, its use, as well as the moldings, films, fibers and foams found. Preferred embodiments of Invention are the subclaims refer to.

• – ein Aluminiumorganyl, oder
• – ein Aluminiumorganyl und ein Hydrid oder Organyl eines Alkalimetalls,

zugefügt.In the process of the present invention, a rubber solution is prepared in step 1) in a first reactor from the diene monomers, or from the diene monomers and the styrenic monomers, with an alkali metal organyl as initiator and with the use of a solvent, and thereafter

• An aluminum organyl, or
• An organoaluminum and a hydride or organyl of an alkali metal,

added.

When Diene monomers are all polymerizable dienes into consideration, in particular 1,3-butadiene (short: butadiene), 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethylbutadiene, Isoprene, piperylene or mixtures thereof. Preference is butadiene.

When Styrenic monomers are all vinylaromatic monomers suitable, for example Styrene, α-methylstyrene, p-methylstyrene, ethylstyrene, tert-butylstyrene, vinylstyrene, vinyltoluene, 1,2-diphenylethylene, 1,1-diphenylethylene or mixtures thereof. Styrene is particularly preferably used.

In a preferred embodiment the styrene monomer used is styrene, and the diene monomer is butadiene. It can also mixtures of these monomers can be used.

In addition, you can concomitantly use other comonomers, for example, with a proportion of 0 to 50, preferably 0 to 30 and particularly preferably 0 to 15 wt .-%, based on the total amount of the monomers used in step 1). Suitable examples are acrylates, in particular C _1-12 -alkyl acrylates such as n- or tert-butyl acrylate or 2-ethylhexyl acrylate, and the corresponding methacrylates, such as methyl methacrylate (MMA). Epoxides such as ethylene oxide or propyfen oxide are also suitable. Further suitable comonomers are mentioned in DE-A 196 33 626 on page 3, lines 5-50 under M1 to M10.

When Organyls are below the organometallic compounds of mentioned elements having at least one metal-carbon σ bond denotes, in particular the alkyl or aryl compounds. Besides can the metal organyls still hydrogen, halogen or via heteroatoms bonded organic radicals, such as alcoholates or phenolates, on the metal contain. The latter are for example whole or partial Hydrolysis, alcoholysis or aminolysis available.

When Alkalimetallorganyl initiators come in particular mono-, bi- or multifunctional alkali metal alkyls, aryls or aralkyls into consideration (but no alkali metal hydrides such as lithium hydride, sodium hydride or Potassium hydride). The organometallic organyl which is preferably used is a lithium organyl a, so an organolithium compound. Geegins are e.g. Ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, Phenyl, diphenylhexyl, hexamethylenedi-, butadienyl-, isoprenyl-, Polystyryllithium or the multifunctional compounds 1,4-dilithiobutane, 1,4-dilithio-2-butene or 1,4-dilithiobenzene. Preference is given to using sec-butyllithium.

It is thought that styrene and the alkali metal organyl are oligomeric polystyrenes rol-alkali metal compound of Polystyrylanion and alkali metal cation forms and the polymerization takes place at Polystyrylanion. Accordingly, a compound [polystyryl] ^⊝ Li ^⊕ forms from styrene and lithium organyl. During and also after the end of the polymerization, ie even after the monomers have been consumed, "living" polymer chains are present in the reaction mixture. "Living" means that upon renewed addition of monomer, the polymerization reaction would start again immediately without having to add polymerization initiator again.

The needed Amount of alkali metal organyl initiator depends i.a. after this desired Molecular weight (molecular weight) of the polymer being prepared should, according to the type and amount of Aluminiumorganyls used (see below) and after the polymerization temperature. Usually used if 0.0001 to 10, preferably 0.001 to 1 and more preferably 0.01 to 0.2 mol% of alkali metal organyl initiator, based on the Total amount of monomers used in stage 1). It can too several alkali metal organyls are used.

The Polymerization is carried out in the presence of a solvent. suitable Solvents are e.g. aliphatic, isocyclic or aromatic hydrocarbons or hydrocarbon mixtures, such as benzene, toluene, ethylbenzene, Xylene, cumene, hexane, heptane, octane or cyclohexane. To be favoured solvent with a boiling point above 75 ° C used, such as ethylbenzene, toluene or cyclohexane. ethylbenzene is particularly preferred. The solvent will be later removed during degassing and can be collected, cleaned and reused become.

Organylaluminum, it being possible for the radicals R _1-20 alkyl or C are independently hydrogen, halogen, C _{6- 20} aryl those of the formula R ₃ Al may be used. Preferred aluminum organyls are the aluminum trialkyls such as triethylaluminum (TEA), tri-isobutylaluminum (TIBA), tri-n-butylaluminum, tri-iso-propylaluminum, tri-n-hexylaluminum, and dialkylaluminum hydrides such as diethylaluminum hydride (DEAH) or di-isobutylaluminum hydride (DIBAH ). Particular preference is given to using TEA or TIBA, particularly preferably TEA. Organylaluminum compounds which can be used are those which are formed by partial or complete hydrolysis, alcoholysis, aminolysis or oxidation of alkyl or arylaluminum compounds. Examples are diethylaluminum ethoxide, diisobutylaluminum ethoxide, diisobutyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum (CAS No. 56252-56-3), methylaluminoxane, isobutylated methylaluminoxane, isobutylaluminoxane , Tetraisobutyldialuminoxane or bis (diisobutyl) alumina.

The Aluminum organyls are only after the polymerization of the diene monomers, or diene monomers and styrene monomers, added, ie to the solution of finished rubbers given. Accordingly, they do not work, as in the Method of the prior art, as a retarder (additives, by the rate of polymerization is reduced and so the Control polymerization of the rubber monomers). It was found, that by addition of the organoaluminum after the polymerization the viscosity the rubber solution is significantly reduced. possibly destroyed the organoaluminum at least partially the dimeric lithium complexes, which are present in the rubber solution after the polymerization, whereby the viscosity sinks.

In addition, will supposes that the aluminum organyls are the living polymer chains stabilize. In particular, the aluminum organyls apparently prevent a thermal degradation of the living chains in the transfer of the Rubber in the second reactor, which is preferably at elevated temperature , see below.

The needed Amount of aluminum organyl depends i.a. by type and amount of used alkali metal organyl initiator, and the viscosity of the rubber solution. Usually one uses 0.0001 to 10, preferably 0.001 to 5 and special 0.01 to 2 mol% of organoaluminum, based on the total amount of in stage 1) used monomers. It is understood that too Several aluminum organyls can be used.

In addition to Organoaluminum may be a hydride or organyl of an alkali metal be used. As alkali metal hydrides are preferably lithium hydride, Sodium hydride or potassium hydride, more preferably sodium hydride, into consideration. Suitable alkali metal organyls were already above called. It is understood that also several alkali metal hydrides or organyls can be used. The alkali metal hydride or -organyl is as well as the organoaluminum after the polymerization of the rubber added. In this case, aluminum organyl and alkali metal hydride or organyl separately, or preferably together, admit.

The needed Amount of alkali metal hydride or organyl depends i.a. to Type and amount of organoaluminum used, and according to the viscosity of the Kautschuklö solution. Usually one uses 0.0001 to 10, preferably 0.001 to 5 and special 0.01 to 2 mol% of alkali metal hydride or organyl, based on the Total amount of the monomers used in stage 1) and calculated as the sum of alkali metal hydride and alkali metal organyl, however not including the amount of the alkali metal organyl initiator initially added (in the preparation of the rubber solution).

you the alkali metal organyl, the aluminum organyl and optionally the Alkali metal hydride as such, or preferably dissolved or supended in an inert solvent or use suspending agents, for example ethylbenzene, Cyclohexane or toluene. As a suspending agent for the alkali metal hydride is e.g. mineral oil suitable.

Prefers is made of aluminum organyl and alkali metal hydride or organyl in advance a mixture, which is then added to the rubber solution. Especially preferably contains this mixture in addition Styrene or other styrenic monomers. The preparation of this mixture is preferably carried out with the concomitant use of a solvent or suspending agent. In particular, inert hydrocarbons, more precisely aliphatic, are suitable. cycloaliphatic or aromatic hydrocarbons, such as Cyclohexane, methylcyclohexane, pentane, hexane, heptane, isooctane, benzene, Toluene, xylene, ethylbenzene, decalin or paraffin oil, or their mixtures. Ethylbenzene is particularly preferred.

to Preparation of the mixture can be, for example, solvent, Styrene and the alkali metal hydride or organyl present, and thereafter Add the aluminum organyl. It is beneficial to ripen this mixture after a while (Aging), for example 2 minutes to 24 hours. The aging process is probably due to a complex formation of the metal compounds, the slower than the mixing process. Mixing the components can be carried out in any mixing unit, preferably in those that can be charged with inert gas. For example, are suitable stirred reactors with anchor stirrer or shaker. For the continuous Production of specially heatable pipes with static Mixing elements. The ripening can also be carried out in a continuous flow stirred tank or in a pipe section whose volume coincides with the flow rate determines the maturity period.

The in stage 1) of the process according to the invention present molar ratios of organoaluminum, alkali metal organyl and alkali metal hydride can vary. The molar ratio of organoaluminum to alkali metal organyl in step 1) is usually 10 to 1000, preferably 20 to 500 and in particular 50 to 200 mol% Aluminum from the organoaluminum, based on the amount of alkali metal from the alkali metal organyl.

The molar ratio of aluminum organyl to alkali metal hydride or organyl in the stage 1) is usually 10 to 200, preferably 20 to 200 and in particular 50 to 150 mol% Alkali metal from the alkali metal hydride or organyl based on the amount of aluminum from the aluminum organyl.

The molar ratio of aluminum organyl to the sum of all alkali metal compounds, ie Alkalimetallorganyl and alkali metal hydride, is in stage 1) in the rule 5 to 500, preferably 10 to 300 and in particular 20 to 100 mol% Aluminum from the organoaluminum, based on the total amount of substance Alkali metal (sum of the alkali metal organyl initiator, and the Alkali metal hydride or further alkali metal organyl).

In addition, can in the preparation of the rubber in stage 1) and / or the Hard matrix in step 2), polar compounds or Lewis bases. They are basically All literature known additives of anionic polymerization suitable. They generally contain at least one O, N, S or P atom that over has a lone pair of electrons. Preferred are ethers and amines, e.g. Tetrahydrofuran (THF), diethyl ether, Tetrahydropyran, dioxane, crown ethers, alkylene glycol dialkyl ethers, e.g. Ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, N, N, N ', N'-tetramethylethylenediamine, N, N, N ', N' ', N' '- Pentamethylentriamin, 1,2-bis (piperidino) ethane, pyridine, N, N, N ', N', N ", N" -hexamethyltriethylenetriamine and phosphoric acid hexamethyltriamide. Preferred is THF.

The Lewis bases act as activators and in many cases increase the conversion of the polymerization reaction or increase the reaction rate. Moreover, if added before or during rubber polymerization, they are able to control the proportions of the various vinyl linkages in the butadiene and isoprene polymers, respectively, and thus to influence the microstructure of the rubber. in particular In particular, in the styrene-butadiene block copolymers, in the polybutadiene and in the polyisoprene, the content of 1,2-vinyl linkages in the polybutadiene or polyisoprene can be controlled. Since the mechanical properties of these rubbers are also determined by the 1,2-vinyl content of the polybutadiene or polyisoprene, the process thus makes it possible to prepare HIPS.

If the Lewis bases increase the reaction rate, their amount is expediently so that the reaction rate of the entire approach smaller than in an approach that is without the addition of retarding Components performed becomes. This is done using less than 500 mol%, preferably less than 200 mol% and in particular less than 100 mol% of the Lewis base, based on the alkali metal organyl.

ever after, whether the Lewis bases to control the rubber microstructure or used to accelerate the reaction, they can be used before or after the rubber synthesis. With an addition after In rubber production, the Lewis base can be used e.g. along with the aluminum organyl, or together with the aluminum organyl and the alkali metal hydride.

The other polymerization conditions, for example temperature, Pressure and polymerization time, are usually chosen similar to in the anionic polymerization known to those skilled in the art of styrene and diene monomers.

by virtue of of their living character, the polymerization reaction starts renewed monomer addition without re-addition of initiator immediately back to. Thus, Step 1) after the polymerization usually becomes not by adding a chain stopper such as water or alcohol, canceled. However, you can the reaction by addition of a molar excess, based on the initiator, "freeze" on Aluminiumorganyl.

step 1) of the method according to the invention can be discontinuous or continuous, in any pressure and temperature-resistant reactor are carried out, it is possible in principle remixing or non-remixing Reactors (i.e. reactors with stirred tank or tubular reactor behavior). The procedure leads depending on Choice of initiator concentration and composition, specifically applied procedure and other parameters, such as temperature and possibly temperature profile, to polymers with high or low Molecular weight. For example, stirred tanks, tower reactors, loop reactors are suitable and tubular reactors or tube bundle reactors with or without fittings. Built-ins can be static or movable Be internals. The polymerization can be one-stage or multi-stage carried out become. Preference is given to polymerizing discontinuously in stage 1), for example in a stirred tank.

Further Details on the design of the reactors and the operating conditions can be found in the documents WO 98/07765 and WO 98/07766, on the express here is referenced.

you receives in step 1) of the process, a reaction mixture comprising the rubber polymer solved in an inert solvent contains. According to the invention this rubber solution do not dilute with styrene or other styrenic monomer before they are transferred to the second reactor.

The obtained rubber polymers are, for example, homopolymers such as Polybutadiene (PB) and polyisoprene (PI), as well as copolymers such as styrene-butadiene Blockcopoly mers (S-B-polymers). Preferably, the rubber is selected from Polybutadiene and styrene-butadiene block copolymers.

The Styrene-butadiene block copolymers may be e.g. linear diblock copolymers S-B or triblock copolymers S-B-S or B-S-B or other multi-block copolymers be (S = styrene block, B = butadiene block), as they are anionic Polymerization obtained by the process according to the invention. The block structure arises essentially by first styrene alone anionic polymerized, creating a styrene block. After consumption the styrene monomer is changed to the monomer by monomeric Add butadiene and anionically polymerized to a butadiene block (so-called sequential Polymerization). The resulting diblock polymer S-B can by another monomer change to styrene to give a triblock polymer S-B-S may be polymerized if desired. The same applies mutatis mutandis for triblock copolymers B-S-B.

In the triblock copolymers, the two styrene blocks can be the same size (same molecular weight, ie symmetrical structure S ₁ -BS ₁ ) or different sizes (different molecular weight ie asymmetric structure S ₁ -BS ₂ ). The same applies mutatis mutandis to the two butadiene blocks of Blockcopo polymeric BOD. Of course, block sequences SSB or S ₁ -S ₂ -B, or SBB or SB ₁ -B ₂ , are possible. The above are the indices for the block sizes (block lengths or molecular weights). The block sizes depend, for example, on the monomer amounts used and the polymerization conditions.

Instead of the rubber-elastic "soft" butadiene blocks B or in addition to the blocks B, blocks B / S may also be present. They are also soft and contain butadiene and styrene, for example, randomly distributed or tapered structure (tapered = gradient of styrene-rich to styrene-poor or vice versa). If the block copolymer contains multiple B / S blocks, the absolute amounts, and the relative proportions, of styrene and butadiene in the individual B / S blocks may be the same or different, yielding different blocks (B / S) ₁ , (B / S) ₂ , etc.

The mentioned block copolymers, as well as usually the homopolymers, one (described above) have linear structure. However, also branched or star-shaped structures are possible and for some Applications preferred. Branched block copolymers are obtained in known manner, e.g. by grafting reactions of polymeric "side branches" onto a polymer backbone.

Star-shaped block copolymers are formed, for example, by reacting the living anionic chain ends with an at least bifunctional coupling agent. Such coupling agents are described, for example, in US Pat. Nos. 3,985,830, 3,280,084, 3,637,554 and 4,091,053. Preferred are epoxidized glycerides (eg epoxidized linseed oil or soybean oil), silicon halides such as SiCl ₄ , or divinylbenzene, also polyfunctional aldehydes, ketones, esters, anhydrides or epoxides. Also suitable for the dimerization are dichlorodialkylsilanes, dialdehydes such as terephthalaldehyde and esters such as ethyl formate. By coupling identical or different polymer chains it is possible to produce symmetrical or asymmetrical star structures, ie the individual star branches can be identical or different, in particular contain different blocks S, B, B / S or different block sequences. Further details on star-shaped block copolymers can be found, for example, in WO 00/58380.

The used above monomer names styrene and butadiene are also exemplary for other vinyl aromatics or dienes.

• – Styrolmonomer, und
• – ein Aluminiumorganyl oder Magnesiumorganyl, und
• – ein Hydrid oder Organyl eines Alkalimetalls als Initiator,

zugefügt, und die erhaltene Mischung polymerisiert.In stage 2) of the process according to the invention, the rubber solution obtained in stage 1) is converted into a second reactor without prior dilution with styrene

• Styrene monomer, and
• An organoaluminium or magnesium organyl, and
• A hydride or organyl of an alkali metal initiator,

added, and the resulting mixture polymerized.

To transfer the rubber solution become common conveyors used, in particular pumps. Suitable pumps are, for example screw conveyors or - especially preferred - gear pumps. You can use the rubber solution also by gas pressure, e.g. Nitrogen gas, promote.

Prefers becomes the rubber solution to be transferred 0 to 150, preferably 40 to 100 and particularly preferably 50 to 80 ° C, tempered.

in the second reactor adds Add the styrene monomer that is used to make the hard matrix HIPS is required. Suitable styrenic monomers were further already mentioned above. Preference is given to using styrene or α-methylstyrene, particularly preferably styrene.

In addition to the styrene monomers can other comonomers are used, as already mentioned. Their share is usually 0 to 50, preferably 0 to 30 and more preferably 0 to 15 wt .-%, based on the total amount of those used in step 2) Monomers.

In the second reactor will also an organoaluminum or magnesium organyl, and a hydride or Organyl of an alkali metal supplied. Suitable aluminum organyls, Alkali metal hydrides and alkali metal organyls have already been described.

there can the compounds used in stage 1) or stage 2) identical or different from each other.

Also with regard to the preferred and particularly preferred organoaluminum compounds, Alkali metal hydrides and alkali metal organyls apply the above statements. Preferred organoaluminum compounds are again TIBA and TEA, in particular TEA. Particularly preferred alkali metal organyl is sec-butyl lithium, and particularly preferred alkali metal hydride is sodium hydride.

Suitable magnesium organyls are those of the formula R ₂ Mg, where the radicals R have the meaning given above for the organoaluminum compounds. Dialkylmagnesium compounds, in particular the ethyl, propyl, butyl, hexyl or octyl compounds available as commercial products, are preferably used. Particular preference is given to using the hydrocarbon-soluble (n-butyl) (s-butyl) magnesium.

Different than in step 1), in step 2) the aluminum organyl (or magnesium organyl) added before the polymerization and acts as a retarder, so serves the reaction control. The required in stage 2) amount of aluminum or Magnesium organyl depends i.a. according to the type and quantity of the stage 1) and 2) of the method alkali metal organyls or hydrides used, and after the polymerization temperature. Usually one uses 0.0001 to 10, preferably 0.001 to 5 and especially 0.01 to 2 mol aluminum or magnesium organyl, based on the total amount of monomers used in stage 2) and calculated as the sum of aluminum organyl and magnesium organyl.

The in stage 2) needed Amount of alkali metal hydride or organyl depends i.a. to the desired one Molecular weight (molecular weight) of the polymer being prepared should, according to the type and amount of aluminum or Magnesiumorganyls used and after the polymerization temperature. As a rule, one uses 0.0001 to 10, preferably 0.001 to 1 and more preferably 0.01 to 0.2 mol% of alkali metal hydride or organyl based on the Total amount of monomers used in stage 2). There can also be several Alkali metal hydrides or organyls be used.

The molar ratios of aluminum and magnesium organyl, alkali metal organyl and alkali metal hydride present in step 2) of the process according to the invention can vary. The molar ratio of aluminum or magnesium _organyl to alkali metal _organyl in stage 2) is usually 0.1: 1 to 20: 1, preferably 0.2: 1 to 10: 1, calculated as molar ratio (Al + Mg) / M _organyl ( M = alkali metal). The molar ratio of aluminum or magnesium organyl to alkali metal hydride in stage 2) is usually 0.2: 1 to 5: 1, preferably 0.5: 1 to 1.5: 1, calculated as molar ratio (Al + Mg) / M _Hydride .

The molar ratio of aluminum or magnesium organyl to the sum of all alkali metal compounds, ie alkali metal organyl and alkali metal hydride, in step 2) is generally 0.1: 1 to 5: 1, in particular 0.5: 1 to 1.5: 1, calculated as molar ratio (Al + Mg) / M _{organyl + hydride} .

The Order of addition of styrene monomer, aluminum or magnesium organyl and alkali metal hydride or organyl, is preferably chosen such that the styrenic monomer after or together with the aluminum or magnesium organyl and the alkali metal hydride or organyl is metered to a prevent premature polymerization of styrene monomers. If one adds the components one after the other one can, for example first the aluminum or magnesium organyl, then the alkali metal hydride or -organyl, and finally Add the styrene monomer.

Prefers are aluminum or magnesium organyl and alkali metal hydride or - organyl added as a mixture that is prepared in advance as it continues has already been described above.

you may re-add an inert solvent in step 2). suitable solvent have already been mentioned. However, no further solvent is preferred added so at the later Working up only the solvent added in the rubber synthesis in stage 1) must be removed again.

Usually is polymerized in step 2) at 50 to 250, preferably 75 to 200 and more preferably 80 to 180 ° C. To pressure and duration of polymerization the information on level 1 applies).

step 2) of the process may be batchwise or continuously be carried out in any pressure and temperature-resistant reactor, as already described in step 1). Preferably polymerized in stage 2) continuously, for example in a tower reactor or tubular reactor.

In a preferred embodiment, the first reactor (stage 1)) is operated discontinuously and the second reactor (stage 2)) is operated continuously. It is understood that in both stages each instead of one zigen reactor several reactors can be used. For example, in stage 1), the rubber may be polymerized in a stirred tank cascade, and / or the matrix in stage 2) in several tower reactors or tubular reactors connected in series.

After completion of the polymerization, the polymerization reaction is stopped by adding a chain stopper which irreversibly terminates the living polymer chain ends. Suitable chain terminators are all proton-active substances, and Lewis acids. Suitable examples are water (preferred), and C ₁ -C ₁₀ alcohols such as methanol, ethanol, isopropanol, n-propanol and the butanols. Also suitable are aliphatic and aromatic carboxylic acids such as 2-ethylhexanoic acid, and phenols. Also, inorganic acids such as carbonic acid (solution of CO ₂ in water) and boric acid can be used.

The Stop agent can either be used as such or else in the form of a terminator mixture containing the chain terminator, mineral oil (see below) and if necessary a usual emulsifier. The emulsifier stabilizes due to its surface-active properties Mixture of the polar chain terminator and the nonpolar polymer solution.

The Reaction mixture is usually after stopping the reaction worked up, for example by degassing. It contains beside the desired one impact-resistant Polystyrene, for example, those used in polymerization and demolition Auxiliary and accompanying substances as well as possibly unreacted monomers (so-called residual monomers), and optionally Oligomeric or low molecular weight polymers as undesirable by-products the polymerization. By degassing, for example by means of conventional Degassing devices such as degassing extruder, partial evaporator, Strand degasser or vacuum pots, are residual monomers and oligomers and in particular the in step 1) added solvent away.

• a) Polybutadien bzw. Polyisopren mit einem bevorzugten gewichtsmittleren Molekulargewicht Mw von 10.000 bis 500.000, bevorzugt 30.000 bis 300.000,
• b) Styrol-Butadien-Zweiblockcopolymere S-B mit einem Styrolgehalt von 1 bis 80, bevorzugt 5 bis 50 Gew.-%. Bevorzugt betragen die Molekulargewichte Mw für den Styrolblock S 1000 bis 200.000, insbesondere 5000 bis 100.000 und für den Butadienblock B 20.000 bis 300.000, insbesondere 50.000 bis 150.000,
• c) Styrol-Butadien-Styrol-Dreiblockcopolymere S₁-B-S₂ mit einem Styrolgehalt von 1 bis 80, bevorzugt 5 bis 50 Gew.-%. Bevorzugt betragen die Molekulargewichte Mw für den ersten Styrolblock S₁ 1000 bis 150.000, insbesondere 5000 bis 100.000, für den Butadienblock B 20.000 bis 300.000, insbesondere 50.000 bis 150.000 und für den zweiten Styrolblock S₂ 1000 bis 150.000, insbesondere 5000 bis 100.000. Angegeben sind die gewichtsmittleren Mw in g/mol,
• d) Mischungen der Blockcopolymere b) und c),
• e) Mischungen des Polybutadiens a) mit den Blockcopolymeren b) und/oder c).

The product of the process gives impact-modified polystyrene (HIPS) containing a rubber component and a hard matrix. Suitable rubber components are, for example:

• a) polybutadiene or polyisoprene having a preferred weight-average molecular weight Mw of from 10,000 to 500,000, preferably from 30,000 to 300,000,
• b) styrene-butadiene diblock copolymers SB having a styrene content of 1 to 80, preferably 5 to 50 wt .-%. The molecular weights Mw for the styrene block S are preferably from 1000 to 200 000, in particular from 5000 to 100 000, and for the butadiene block B from 20 000 to 300 000, in particular from 50 000 to 150 000.
• c) styrene-butadiene-styrene triblock copolymers S ₁ -BS ₂ having a styrene content of 1 to 80, preferably 5 to 50 wt .-%. The molecular weights Mw for the first styrene block S ₁ are preferably from 1000 to 150 000, in particular from 5000 to 100 000, for the butadiene block B from 20 000 to 300 000, in particular from 50 000 to 150 000 and for the second styrene block S _{2 from} 1000 to 150 000, in particular from 5000 to 100 000. The weight-average Mw in g / mol,
• d) mixtures of the block copolymers b) and c),
• e) mixtures of the polybutadiene a) with the block copolymers b) and / or c).

The weight average molecular weight Mw of the hard matrix is usually 50,000 to 300,000, preferably 100,000 to 250,000 g / mol.

The Invention relates in addition to the method described above as well as the impact polystyrene obtainable by the polymerization process (HIPS).

the Impact-resistant polystyrene according to the invention can various additives and / or processing aids added to give it certain qualities. In a preferred embodiment you add a mineral oil, e.g. White oil, in quantities from e.g. 0.1 to 10, preferably 0.5 to 5 wt .-% added, whereby the mechanical properties are improved, in particular itself the elongation at break elevated.

In a further preferred embodiment is an additional additive an antioxidant or a stabilizer against exposure to light (in short: light stabilizer), or mixtures thereof, in amounts of, for example, 0.01 to 0.3, preferably 0.02 to 0.2 By weight is used. Increase these additives the durability of the polymer against air and oxygen, or against UV radiation, and increase so the weathering and aging resistance of the polymer. The Quantities are based on the polymer obtained.

In addition to the mineral oils, antioxidants and light stabilizers, the polymers may contain other additives or processing aids, for example lubricants or mold release agents, colorants such as Pig or dyes, flame retardants, fibrous and powdery fillers or reinforcing agents or antistatic agents, as well as other additives, or mixtures thereof. The individual additives are used in the usual quantities, so that further information is unnecessary. The additives can be added, for example, during the work-up of the polymer melt, and / or the solid polymer (for example polymer granules) by mixing methods known per se, for example by melting in an extruder, Banbury mixer, kneader, roll mill or calender.

Out the impact polystyrenes of the invention, can be shaped body (also semi-finished products) produce foils, fibers and foams of all kinds.

object Accordingly, the inventions are also the use of the impact-resistant polystyrene according to the invention for the production of moldings, Films, fibers and foams, as well as those from the impact resistant Polystyrene available Moldings, Foils, fibers and foams.

The inventive method is more economical than the methods of the prior art. As it is without styrene dilution the rubber solution can be a cheaper, smaller rubber synthesis reactor can be used. By saving the dilution time shortened the cycle time of the rubber synthesis, what the profitability of the overall procedure improved. In addition, the intermediate storage the rubber solution easily possible, since it does not contain styrene, that could polymerize prematurely.

• – Styrol, gereinigt, von BASF
• – Butadien, gereinigt, von BASF
• – sec.-Butyllithium (s-BuLi) als 12 gew.-%ige Lösung in Cyclohexan, fertige Lösung von Fa. Chemetall
• – Natriumhydrid, als 60 gew.-%ige Suspension in Mineralöl, fertige Suspension von Fa. Chemetall
• – Triisobutylaluminium (TIBA) als 20 gew.-%ige Lösung in Toluol, fertige Lösung von Fa. Crompton
• – Triethylaluminium (TEA) als 20 gew.-%ige Lösung in Ethylbenzol, fertige Lösung von Fa. Crompton
• – Tetrahydrofuran (THF), von BASF
• – Toluol, gereinigt, von BASF
• – Ethylbenzol, gereinigt, von BASF
• – Irganox^®1076 = Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionat (CAS 2082-79-3), von Fa. Ciba Specialty Chemicals
• – Mineralöl Winog^® 70, ein medizinisches Weißöl von Fa. Wintershall
• – Wasser als Kettenabbruchmittel.

The following compounds were used, where "purified" means that it was cleaned with aluminoxane and dried All reactions were carried out with exclusion of moisture.

• - Styrene, purified, from BASF
• - Butadiene, purified, from BASF
• Sec-butyllithium (s-BuLi) as a 12% strength by weight solution in cyclohexane, finished solution from Chemetall
• - Sodium hydride, as a 60 wt .-% suspension in mineral oil, finished suspension from. Chemetall
• - Triisobutylaluminum (TIBA) as a 20 wt .-% solution in toluene, finished solution from. Crompton
• - Triethylaluminum (TEA) as a 20 wt .-% solution in ethylbenzene, finished solution from. Crompton
• - Tetrahydrofuran (THF), from BASF
• - Toluene, purified, from BASF
• - Ethylbenzene, purified, from BASF
• - Irganox ^® 1076 = octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS 2082-79-3), of Ciba Specialty Chemicals.
• - Mineral oil Winog ^® 70, a medical white oil from Wintershall
• - Water as chain stopper.

The The rules given in points 2 and 3 below are general Regulations. The individual values of the variables y1 to y3 and x1 to x30 are summarized in Tables 1 and 2.

1. Production the mixtures of aluminum organyl and alkali metal organyl or hydride

Mixture A: TIBA / styrene / s-BuLi:

at 25 ° C were in a 15 liter stirred tank Submitted 1980 g of toluene and with stirring y1 g of styrene and y2 g of 12 wt .-% solution of s-BuLi in cyclohexane added. 10 minutes thereafter, 913 g of the 20% strength by weight solution of TIBA in toluene were added, and cooled the solution to 50 ° C. It was kept at this temperature for 3 hours, then another 10 Hours at 23 ° C.

Mixture B: TEA / styrene / Close

at 25 ° C were in a 15 liter stirred tank 4182 g of ethylbenzene initially charged and with stirring with y1 g of styrene and y2 g of 60 wt.% Suspension of NaH in mineral oil and y3 g THF, mixed. 10 minutes later, 380 g of the 20% strength by weight solution of TEA in ethylbenzene were added added, and cooled the solution to 50 ° C. It was kept at this temperature for 3 hours.

The Tables 1 and 2 name the individual values of the variables y1 to y3.

2. Preparation of polybutadiene rubbers K1 V to K7

In a 1500 l stirred tank were stirred Submitted 411 kg of ethylbenzene and added x1 kg of styrene. The Mixture was at 50 ° C tempered and at this temperature x2 g of 12 wt% solution of s-BuLi added in cyclohexane. After 10 minutes, the temperature was brought to 60 ° C., and then x3 g of THF and x4 kg of butadiene were added (Bu.). After 20 minutes, cooled to 60 ° C and added x5 kg of butadiene. After another 25 min cooled again at 60 ° C and added x6 kg of butadiene. The other butadiene portions x7, x8 and x9 were added in the same way as the portion x6. x10 min after addition of the last portion x9 was given as the last monomer portion Add x11 kg of styrene. After a further 30 min, it was cooled to 80 ° C and gave either x12 g of the 20% by weight TEA solution in ethylbenzene, or x12 g of the mixture B, added. The aforementioned cooling was done by means of each Evaporative cooling.

The obtained rubber solution had a solids content (FG) of x13% by weight. It was in the comparative examples diluted by dilution time within 60 min, x14 kg styrene added were. In the examples according to the invention was not diluted with styrene (x14 = 0) and the dilution time accounted for.

you received a rubber solution with a solids content of x15% by weight. She was in a buffer tank stored.

The Polymers were after GPC analysis (gel permeation chromatography in tetrahydrofuran, calibration with polybutadiene standards) a monomodal distribution. The gas chromatographic certain residual monomer content of butadiene was less than 10 ppm (w). The weight average molecular weight Mw was determined by GPC as described above and was x16 kg / mol.

table 1 summarizes the individual values of the variables x1 to x16.

Table 1: Rubber Production: Variables y1 to y3 and x1 to x16 (V for comparison, Bu butadiene, FG solids content)

3. Preparation of the impact-resistant polystyrenes HIPS1 to HIPS11 with stirred tank / tower reactor

The HIPS production (polymerization of the matrix) was carried out continuously as described below, for which the rubber solution is continuous to the buffer tank was removed. A double-walled 50 l stirred tank was used with standard anchor stirrer. Of the Reactor was for 25 bar absolute pressure designed as well as with a heat transfer medium and by boiling cooling for isothermal reaction tempered.

In the stirred tank were stirred at 115 rpm continuous x17 kg / h styrene, x18 kg / h of the rubber solution (see above point 2 and Table 1) and x19 g / h of the mixture A or B (see above point 1), dosed and the boiler at a constant reactor wall temperature of 130 to 150 ° C. At the outlet of the stirred tank the solids content was x20% by weight.

The Reaction mixture was added to either a stirred 29 L tower reactor, or in a tube reactor of 7 m in length and 500 mm diameter, promoted (x21), with two of the same size Heating zones was provided, the first zone at 140 ° C and the second zone at 180 ° C Reactor wall temperature was maintained.

The discharge of the tower reactor was charged with x22 g / h of water and then with x23 g / h of an additive mixture I was added, which was previously prepared from x24 g Irganox ^® 1076 and x25 kg mineral oil Winog ^® 70, then passed through a mixer and finally through a heated to 250 ° C pipe section. Thereafter, the reaction mixture was fed to the degassing via a pressure control valve in a operated at x26 ° C partial evaporator and expanded in a operated at 10 mbar absolute pressure and x27 ° C vacuum pot.

The resulting polymer melt was discharged with a screw conveyor, and then mixed with x28 g / h of an additive mixture II, which was previously prepared from x29 g Irganox ^® 1076 and x30 kg of Winog ^® 70 mineral oil, then passed through a mixer and granulated. The turnover was quantitative.

The HIPS obtained had the following residual monomer contents, which as already were determined: styrene less than 5 ppm (w), ethylbenzene less than 5 ppm (w).

table 2 summarizes the individual values of the variables x17 to x30.

Table 2: HIPS production: variables x17 to x32 (V for comparison, Tu. Tower, Ro. Tube, FG solids content)

4. Repetition of the examples according to the invention K4, K6 and K7 with smaller stirred tank

In the above, in the rubber synthesis (Examples K1V to K7), a 1500 liter reactor was used to carry out also the comparative examples with styrene dilution in this reactor can.

Now were the examples of the invention K4, K6 and K7 without styrene dilution in a smaller stirred tank repeated, whose volume was only 1000 liters. This smaller reactor proved to be big enough. From the obtained rubber solutions HIPS was prepared as described under point 3.

The Examples show that the process without styrene dilution of rubber solution could be operated with improved efficiency.

Claims (11)

Process for the production of impact-resistant polystyrene from diene monomers and styrenic monomers by anionic polymerization, where you are 1) in a first reactor of the diene monomers, or from the diene monomers and the styrenic monomers, with an alkali metal organyl as an initiator and with the concomitant use of a solvent, produces a rubber solution, and then - one Organoaluminum, or - one Organoaluminum and a hydride or organyl of an alkali metal, inflicts, and after that 2) the resulting rubber solution is transferred to a second reactor, there Styrene monomer, and - one Organoaluminium or magnesium organyl, and - a hydride or organyl of an alkali metal as an initiator, inflicts, and polymerizing the resulting mixture, and wherein the rubber solution in transferred the second reactor, without previously dilute with styrene monomer. Method according to claim 1, characterized in that that is used as the diene monomer butadiene and as styrene monomer styrene. Process according to claims 1 to 2, characterized that the rubber is selected is made of polybutadiene and styrene-butadiene block copolymers. Process according to claims 1 to 3, characterized in that a lithium organyl is used as alkali metal organyl. Process according to claims 1 to 4, characterized that as aluminum organyl triethylaluminum (TEA) or triisobutylaluminum (TIBA) or mixtures thereof. Process according to claims 1 to 5, characterized that is used as the alkali metal hydride sodium hydride. Process according to claims 1 to 6, characterized that in the production of the rubber solution tetrahydrofuran co-used. Process according to claims 1 to 7, characterized that the first reactor is discontinuous and the second reactor is operated continuously. impact-resistant Polystyrene, available according to the method according to claims 1 to 8th. Use of the impact-resistant polystyrene according to claim 9 for the production of moldings, Foils, fibers and foams. Moldings, Foils, fibers and foams made of impact resistant Polystyrene according to claim 9th