DE102005029019A1 - Preparation of copolymer, useful in the preparation of block copolymer, comprises anionic polymerization of styrol- and diene monomer in the presence of alkalimetalorganyls and aluminumorganyls polymer and in the absence of Lewis base - Google Patents

Abstract

Preparation of copolymer S/B comprises anionic polymerization of styrol monomer and diene monomer in the presence of an alkalimetalorganyls and an aluminumorganyl polymer and in the absence of Lewis base, where the molar ratio of aluminum to alkalimetal is 0.75:1 to 0.95:1. Independent claims are included for: (1) the preparation of blockcopolymer containing at least one copolymer blocks S/B and at least a homopolymerblock S from styrol monomer, or at least a homopolymerblock B from diene monomer, comprising preparing the copolymer block S/B and before or after the above step styrol monomer is polymerized to homopolymerblock S, or diene monomer is polymerized to the homopolymerblock B; (2) a copolymer obtained from the process; and (3) a blockcopolymer obtained from the process.

Description

The The invention relates to a process for the preparation of copolymers S / B of styrenic monomers and diene monomers, the copolymers have a 1,2-vinyl content in the diene content of not more than 20%, by anionic polymerization, characterized in that one without Addition of Lewis bases and in the presence of an alkali metal organyl and an organoaluminum organylated, wherein the molar ratio of aluminum / alkali metal 0.75: 1 to 0.95: 1.

It also concerns the invention the copolymers obtainable by these processes, or block copolymers.

copolymers from styrenic monomers (vinylaromatic monomers, e.g., styrene) and Diene monomers (for example, butadiene or isoprene) can by various polymerization processes are produced, such as by radical or anionic polymerization. The by anionic Polymerization obtained polymers have over the radical way received some advantages on products, i.a. lower residual monomers and oligomer contents. Radical and anionic polymerization are completely different. In the radical polymerization runs the Reaction over free radicals and it will be e.g. used peroxide initiators, whereas anionic polymerization proceeds via "living" carbanions and, for example Alkalimetallorganylverbindungen be used as initiators.

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. The use of so-called retardants (such as Al, Zn) or Mg organyl compounds), which are the reaction rate reduce. The viscosity the reaction mixture increases in anionic rubber production usually so fast that a dilution of the reaction mixture with an inert solvent is required. After consumption of the monomers, i. at the end of Polymerization is preferred with a chain terminator, e.g. a protic substance such as alcohols, broken off. The anionic Polymerization of styrene and / or butadiene is for example in WO 98/07765 and WO 98/07766.

polymerized a mixture of styrene and butadiene anionic, it is based on the strongly different reactivities of styrene and butadiene usually block copolymers: first, the more reactive polymerizes Butadiene to a Homopolybutadienblock, and only after consumption the butadiene monomer polymerizes the styrene to a homopolystyrene block. For certain Applications are however copolymers with a gradient (tapered) or statistical distribution of the styrene and butadiene units along the polymer chain advantageous. The monomer distribution becomes common achieved by concomitant use of Lewis bases as so-called. Randomizer. Such Lewis bases are e.g. Tetrahydrofuran, potassium or sodium alcoholates, or other polar compounds containing O or N atoms, for example Amines.

Indeed the Lewis bases affect the microstructure of the diene rubber, by increasing the content of 1,2-linkages and the content of 1,4-linkages humiliate. This changed in particular the mechanical properties of the copolymer or the moldings produced from it, which is why for some unsuitable for demanding applications.

For certain Applications are also advantageous copolymers that only have a single and not two or more glass transition temperatures (Tg).

The WO-A 99/42506 describes a process for the preparation of block copolymers from vinyl aromatic monomers and dienes in the presence of an alkali metal organyl and a Mg, Al or Zn organyl having a molar ratio (Mg, Al, Zn) to alkali metal from 0.1 to 100. On page 5, lines 13-14 mentioned that with dibutylmagnesium (DBM) and sec-butyllithium (s-BuLi) at one molar ratio Mg / Li over 4, random butadiene / styrene blocks are obtained. information to the 1,2-vinyl linkages are not made.

WO-A 98/07766 teaches, inter alia, a similar process in the presence of a metal alkyl of an at least bivalent element without the addition of Lewis bases. In this case, the molar ratio of metal alkyl to initiator (eg lithium organyl) is 0.5: 1 to 50: 1, preferably it is greater than 1. According to page 7, lines 30-40, the homopolydiene blocks contain small amounts of copolymerized vinylaromatic compounds, the un are distributed symmetrically over the molecule. Examples 9 and 10 disclose styrene-butadiene copolymers made with DBM as the metal alkyl containing about 11 1,2-linkages in the butadiene moiety. However, the document does not teach copolymers containing vinyl aromatic compounds in not only minor amounts. The examples do not use any aluminum compounds as metal alkyls, and the font is silent on the 1,2-vinyl contents available therewith.

The US 2002/0151658 A1 describes the anionic polymerization of et al Styrene and dienes such as isoprene or butadiene with alkali metal organyls as an initiator, where per equivalent Alkali metal organyl at least 0.01 equivalent of a metal alkyl compound, e.g. Triethylaluminum (TEA) or triisobutylaluminum, also used become. According to example 2 and Table 5 on page 7-8 be with sec-butyl lithium as an initiator styrene-butadiene block copolymers produced. In the block copolymers of Experiment Nos. 24219-119 and 24219-121 of Table 5, first a block of styrene and then a block of styrene and butadiene (50/50) polymerized. In the polymerization of the styrene-butadiene block, TEA is co-used, and the molar ratio TEA / Li is 0.5 in experiment 24219-119 and 1.0 in experiment 24219-121. information to the 1,2-vinyl content are not made.

It The task was to remedy the disadvantages described. Especially the task was to provide an alternative method with which copolymers of styrene monomers and diene monomers produce let that have a uniform structure and have only a single glass transition temperature Tg.

Of the uniform structure (Monomer distribution) should be guaranteed even if more than small amounts of styrene monomer are polymerized. The procedure should do without Lewis bases. In addition, after the Method available Copolymers an advantageous, low 1,2-vinyl content in the diene portion exhibit.

Especially The task was to provide a method with which Make copolymers that are built uniformly, only one Tg contain more than low levels of styrene and at the same time have a low 1,2-vinyl content.

Accordingly, were the aforementioned methods, copolymers or block copolymers found. Preferred embodiments The invention can be found in the dependent claims.

at the method according to the invention are styrene monomers and diene monomers by anionic polymerization, polymerized to copolymers S / B. Here, an alkali metal organyl and an aluminum organyl co-used.

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.

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

Prefers to prepare a mixture of styrene monomer and diene monomer, which is then anionically polymerized. The proportion of styrene monomers at the total amount of monomers used is usually 5 to 99, preferably 5 to 95 and particularly preferably 10 to 90 wt .-%. The at 100 wt .-% missing remainder is diene monomer.

When Organyls are the organometallic compounds mentioned Metals understood with at least one metal-carbon σ bond, in particular the alkyl or Aryl compounds. In addition, you 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. It can too Mixtures of different organometallic compounds are used.

The alkali metal organyl acts as an anionic polymerization initiator. In particular, mono-, difunctional or polyfunctional alkali metal alkyls, aryls or aralkyls, the term alkali metal organyl here also being intended to include the alkali metal hydrides, such as lithium hydride, sodium hydride or potassium hydride. It is expedient to use organolithium compounds which are organolithium compounds such as ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, phenyl, diphenylhexyl, hexamethylenedi, butadienyl, isoprenyl, polystyryl lithium or the multifunctional compounds 1,4-dilithiobutane, 1,4-dilithio-2-butene or 1,4-dilithiobenzene. The alkali metal organyl used is preferably sec-butyllithium (s-BuLi).

The aluminum organyl is a so-called retarder and serves to control the reaction by reducing the reaction rate. As organoaluminium compounds it is possible to use those of the formula R ₃ Al, where the radicals R independently of one another are hydrogen, halogen, C _1-20 -alkyl or C _6-20 -aryl. Preferred aluminum organyls are the aluminum trialkyls such as triethylaluminum, tri-iso-butylaluminum, tri-n-butylaluminum, tri-iso-propylaluminum, tri-n-hexylaluminum. Particular preference is given to using triisobutylaluminum (TIBA). 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.

Prefers be in the inventive method Magnesiumorganyle or Zinkorganyle not used, or the reaction mixture contains these compounds only in ineffective quantities. Ineffective amount means that the polymerization reaction by this amount is not essential being affected. Particular preference is given to using, in addition to the alkali metal and organoaluminum also no other organometallic elements of an element the second or third main group or the second subgroup of the periodic table, e.g. the organyls of the elements Be, Mg, Ca, Sr, Ba, B, Ga, In, Tl, Zn, Cd and Hg, respectively they are only ineffective ones Containing quantities of it.

The needed Amount of polymerization initiator (alkali metal organyl) directed u.a. according to the desired Molecular weight (molecular weight) of the polymer being prepared should, according to the type and quantity of the used retarder (aluminum organyl) 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 organyl based on the total amount of used monomers.

The needed Amount of aluminum organyl depends i.a. according to the type of organyl and after the polymerization temperature. Usually one uses 0.0001 to 10, preferably 0.001 to 5 and especially 0.01 to 2 mol% Organonuminum, based on the total amount of monomers used.

The molar ratio directed by retarder aluminum organyl to initiator alkali metal organyl e.g. according to the desired Retardierungswirkung, the polymerization temperature, the type and Amount (concentration) of the monomers used, and the desired Molecular weight of the polymer. It is expediently used as molar ratio of aluminum / alkali metal specified. According to the invention, the molar ratio is aluminum / alkali metal 0.75: 1 to 0.95: 1, preferably 0.78: 1 to 0.92: 1, in particular 0.8: 1 to 0.9: 1 and more preferably 0.82: 1 to 0.88: 1.

Prefers the incorporation of the monomer units in the polymer corresponds to the quantitative ratio of used monomers.

In a preferred embodiment becomes the molar ratio Aluminum / alkali metal chosen such that a statistical Distribution of the monomer units and thus a random copolymer results.

In As a rule, a mixture of styrene monomer and diene monomer is prepared ago, and gives initiator and retarder. This can be initiator and retarders are added separately or together, as such or solved or suspended in a solution or suspending agent (hereinafter collectively as a solvent designated). With joint addition one can also first a Make initiator-retarder mixture and this before use mature, see below. As a solvent for initiator and retarders are especially inert hydrocarbons, more precisely aliphatic, cycloaliphatic or aromatic hydrocarbons, such as cyclohexane, methylcyclohexane, pentane, hexane, heptane, isooctane, Benzene, toluene, xylene, ethylbenzene, decalin or paraffin oil, or their mixtures. Cyclohexane and toluene are particularly preferred.

Likewise, it is possible in advance to prepare an initiator composition from initiator and retarder by the alkali metal organyl, in particular lithium organyl, is mixed with styrene, and then the aluminum organyl is added. For example, anionic polymerization may be carried out in the presence of an initiator composition obtainable by mixing sec-butyllithium and styrene and then adding triisobutylaluminum (TIBA). It is thought that a (poly) styrene-alkali metal compound of (poly) styrylanion and alkali metal cation forms from styrene and the alkali metal organyl and the polymerization proceeds on the (poly) styryl anion. Accordingly, a compound [(poly) styryl] ^⊖ Li ^⊕ forms from styrene and lithium organyl. The notation (poly) styrene or (poly) styryl means that monomeric, oligomeric or polymeric styrenes or styrenes may be present.

you For example, the initiator composition may be after addition of the retarder mature (age) for a while. This also applies to compositions the only organoaluminum and alkali metal organyl, but no styrene contain. The observed aging process is probably due to one Attributed to complex formation of metal compounds slower than that Mixing process expires. The maturing time is usually at least about 2 minutes, preferably at least 5 minutes, in particular at least 20 minutes, and up to 480 hours. The Mixture of the initiator components can be carried out in each mixing unit, for example in a stirred reactor. For the continuous production of specially heatable pipes, if necessary with static mixing elements, or continuous flow stirred tank.

According to the invention in the polymerization of the monomers no Lewis bases co-used. Lewis bases are e.g. Tetrahydrofuran, potassium or sodium alcoholates, or other polar compounds containing O or N atoms, for example Amines.

The Polymerization may be in the absence or presence of a solvent carried out become. If a solvent is used, one expediently an aliphatic, isocyclic or aromatic hydrocarbon or hydrocarbon mixture, such as benzene, toluene, ethylbenzene, xylene, Cumene, hexane, heptane, octane or cyclohexane. Preference is given to solvents with a boiling point above 75 ° C used. Particular preference is given to using toluene or cyclohexane. Unless you have a solvent used, it can be used in the later workup, e.g. by Degassing of the resulting polymer, then e.g. by Collect condensation, clean by distillation if necessary, and reuse.

To Termination of the polymerization, i. after consumption of the monomers, the polymerization is stopped. During and after completion the polymerization, i. even after the monomers are consumed, are present in the reaction mixture "living" polymer chains, so when renewed Monomer added the Polymerisati onsreaktion immediately start again would, without having to add polymerization initiator again. By Addition of a chain stopper will terminate the living polymer chains terminated irreversibly.

As termination agents are all proton-active substances, and Lewis acids, into consideration. Suitable examples are water, 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. Preferred termination agents are alcohols and especially ethanol.

The inventive method for the preparation of the polymers may be discontinuous or continuous, be carried out in any pressure and temperature resistant reactor, where it is basically possible is, remixing or not 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. Further details on the design of the reactors and the operating conditions are the documents WO 98/07765 and WO 98/07766 to remove.

After the polymerization of the monomers and the reaction termination, the reaction mixture can be worked up on the resulting polymer. In addition to the desired polymer, the reaction mixture contains, for example, the auxiliaries and accompanying substances used in the course of polymerization and termination, and possibly unreacted monomers (so-called residual monomers), and optionally oligomers or low molecular weight polymers as undesired by-products of the polymerization. In carrying out the polymerization as Lösungspolymerisa tion is the reaction mixture is a polymer solution and contains as an excipient in particular the solvent. Working up, for example by degassing, removes residual monomers and oligomers and, in particular, the solvent. The degassing is carried out in a conventional manner in customary devices.

According to the invention the copolymer S / B has a 1,2-vinyl content in the diene portion of maximum 20% up. Preferred is the 1,2-vinyl content in the diene portion 5 to 15, in particular 8 to 15 and more preferably 10 to 14%.

In this case, 1,2-vinyl content in the diene fraction, the proportion of 1,2-linkages, based on the sum of 1,2-, 1,4- and 3,4-linkages in the diene portion. The proportion of 1,2-, 1,4- and 3,4-linkages can be determined in a conventional manner, for example by recording ¹ H nuclear magnetic resonance spectra ( ¹ H-NMR), and quantitative evaluation of the NMR spectra obtained.

In a preferred embodiment For example, the copolymer has a single (and not multiple) glass transition temperatures on. Glass transition temperatures become commonplace Way, e.g. using differential scanning calorimetry (DSC). Accordingly, the method of the invention preferably characterized in that the copolymers are one and not several glass transition temperatures exhibit.

Especially The glass transition temperature is preferably depending on the type and quantity ratio of the monomers in the range of -90 up to + 95 ° C, especially -85 up to + 50 ° C, determined by DSC.

With the method according to the invention not only copolymers S / B with a maximum of 20% 1,2-vinyl content can be used but also copolymers with block structure (block copolymers), in which at least one block of such copolymers according to the invention S / B exists. The one or more blocks of the block copolymer may, for example Homopolymer blocks be, or blocks with alternating sequence of monomer units, or blocks with tapered structure, or blocks not according to the invention with more than 20% 1,2-vinyl content. Preferably, the block or blocks are homopolymer blocks Styrene monomer or diene monomer.

The block copolymers according to the invention can be preferably by sequential anionic polymerization produce. The block structure arises essentially from that one first Styrene alone anionically polymerized, creating a styrene block S arises. The co-use of an organoaluminum is as a retarder not mandatory. After consumption of styrene monomers Change the monomers by adding a mixture of monomeric Add butadiene and styrene and anionic, in the presence of retarder and initiator, to one Block S / B of inventive styrene-butadiene copolymer polymerized as described above.

The obtained diblock polymers S-S / B can by changing the monomer again be polymerized on styrene to a triblock polymer S-S / B-S, if desired. The same applies analogously for triblock copolymers B-S / B-B, the preparation of which begins with a polybutadiene block. It is also possible initially to block S / B and then the homopolymer blocks S or B polymerize, i. start with the copolymer block.

Therefore a preferred subject of the invention is also a method for Preparation of block copolymers containing at least one copolymer block S / B and at least one homopolymer block S of styrene monomer, or at least one homopolymer block B of diene monomer, characterized in that the copolymer block S / B after the inventive method and before or after styrene monomers to the homopolymer block S, or diene monomers to the homopolymer block B, polymerized.

In the triblock copolymers, the two styrene blocks can be the same size (same molecular weight, ie symmetrical structure S ₁ -S / BS ₁ ) or different sizes (different molecular weight ie asymmetric structure S ₁ -BS ₂ ). Of course, block sequences SSS / B or S ₁ -S ₂ -S / B, or SS / BB, are possible. The same applies mutatis mutandis to the two butadiene blocks of the block copolymers BS / BB or BBS / B. 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.

Prefers For example, the block copolymer has a block construction of S-S / B or S-S / B-S.

If the block copolymer contains multiple S / B blocks, the absolute amounts, and the relative proportions, of styrene and butadiene in the individual S / B blocks may be the same or different, yielding different blocks (S / B) ₁ , (S / B) ₂ , etc. If more than one S / B block is present, then at least one such block must be according to the invention, ie have the 1,2-vinyl content according to the invention of not more than 20%. Also, four-block and polyblock copolymers are possible.

The block copolymers of the invention may have a linear structure (described above). However, also branched or star-shaped structures are possible. Branched block copolymers are obtained in a known manner, for example 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. Preference is given to epoxidized glycerides (for example epoxidized linseed oil or soybean oil), silicon halides such as SiCl ₄ or also divinylbenzene, as well as 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 one can produce symmetrical or asymmetric star structures, ie the individual star branches can be the same or different, in particular contain different blocks S, B, S / B or different block sequences. Further details on star-shaped block copolymers can be found, for example, in WO 00158380.

The used above monomer names styrene and butadiene are also exemplary for other styrenic monomers (vinylaromatic monomers) or diene monomers.

Of the Diene content of the obtainable by the process according to the invention Copolymer is usually 5 to 95, preferably 10 to 90 and more preferably 15 to 85% by weight, and the remainder of 100% by weight is copolymerized Styrene monomer (in the mentioned Block copolymers relate these quantities only to the S / B block with a maximum of 20% 1,2-vinyl content). Accordingly, the composition is of the resulting polymer not necessarily identical to the next above ratios of the used monomers.

Next the method of polymerization described above the invention also obtainable by the polymerization process Polymers, i. the described copolymers, including those described Block copolymers containing blocks from the copolymers.

The copolymers of the invention, or the molding compositions containing these copolymers, may additionally other Components included. These are in particular conventional additives and processing aids such as. Lubricants or mold release agents, colorants, e.g. pigments or dyes, flame retardants, antioxidants, stabilizers against exposure to light, fibrous and powdery filling or reinforcing agents or antistatic agents, as well as other additives, or mixtures thereof.

The individual additives are used in the usual amounts, so that is more details to spare this. The addition of the additives can according to known mixing method take place, for example by melting in an extruder, Banbury mixer, Kneader, roller mill or calender. However, the components can also be used "cold" and the powdery or granular mixture is only melted and homogenized during processing.

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

With the method according to the invention Copolymers of styrene and diene monomers to simple Make way. Even with more than small amounts copolymerized Styrene monomer they show a uniform structure (monomer distribution). To achieve this, no Lewis bases are required.

The Copolymers of the invention preferably have only a single glass transition temperature, and are characterized by a low 1,2-vinyl content in the diene portion from what their property profile, especially their mechanical Properties, improved.

The polymers of the invention are also characterized by a low content of residual monomers or oligomers. The low content of styrene residual monomers and styrene oligomers makes a subsequent degassing - eg on a vented extruder, associated with higher costs and after Partial thermal damage to the polymer (depolymerization) - makes unnecessary.

• – Styrol, gereinigt, von BASF
• – Butadien, gereinigt, von BASF
• – sec.-Butyllithium (s-BuLi) als 12 gew.-%ige Lösung in Cyclohexan, fertige Lösung von Fa. Chemetall
• – Triisobutylaluminium (TIBA) als 20 gew.-%ige Lösung in Toluol, fertige Lösung von Fa. Crompton,
• – Dibutylmagnesium (DBM) als 1,0 molare Lösung in Cyclohexan
• – Cyclohexan, gereinigt, von BASF
• – Ethanol als Kettenabbruchmittel.

All reactions were carried out with exclusion of moisture under a nitrogen atmosphere in a glovebox. The following compounds were used, where "purified" means that was cleaned with aluminoxane and dried:

• - 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
• Triisobutylaluminum (TIBA) as a 20% strength by weight solution in toluene, ready-made solution from Crompton,
• - Dibutylmagnesium (DBM) as a 1.0 molar solution in cyclohexane
• - Cyclohexane, purified, from BASF
• - Ethanol as a chain stopper.

Preparation of initiator composition:

For the examples From 1 to 14, an initiator composition was prepared in advance. This was at 23 ° C Submitted to cyclohexane and stirring the amounts indicated in the table TIBA solution (or DBM solution for Comparison) and s-BuLi solution was added and the mixture ripened for 24 hours at 23 ° C. The submitted Cyclohexane volume was 10 times the sum of the volumes of TIBA or DBM solution and s-BuLi solution. The table also gives the molar ratios Al / Li and Mg / Li, respectively in the initiator composition. It was the total amount the composition used.

Examples 1 to 4:

It 500 ml of a solution submitted from styrene and butadiene, the exact composition is given in the table. The initiator composition was added with stirring to. Thereafter, at 23 ° C touched, until a solids content of 10 to 15 wt .-% was reached. Then broke the reaction is stopped by adding 10 ml of ethanol. The polymer was isolated by drying in a drying oven under vacuum.

The butadiene content of the polymer and the 1,2-vinyl content in the butadiene portion were determined by taking ¹³ C and ¹ H nuclear magnetic resonance (NMR) spectra and evaluated. In addition, one determined the reactivity _factors r _S = k _SS / k _SBu and r _Bu = k _BuBu / k _BuS , according to the Kelen-Tudos method as described in Kelen et al., J. Polym. Sci. (1977), 15, 3047-3074. Finally, Differential Scanning Calorimetry (DSC) was used to examine whether the polymer had one or more glass transition temperatures Tg. The number of determined Tg is given in the table.

Comparative Example 5V:

example 3 was repeated but no TIBA and only s-BuLi were used.

Comparative Example 6V:

example 2 was repeated, but TIBA and s-BuLi were not in one inventive molar ratio Al / Li of 0.6 (based on the experiment mentioned in the beginning No. 24219-119 of US 2002/0151658 A1, wherein the molar ratio Al / Li 0.5).

Comparative Examples 7V up to 13V:

It the procedure was as in Examples 1 to 4, again s-BuLi but DBM instead of TIBA. There were different monomer ratios and Mg / Li ratios examined.

The Table summarizes the data. Where V is for comparison and nb not determined.

Table (V: for comparison, nb: not determined)

• ¹⁾ in Butadienanteil

used In addition to s-BuLi as an initiator according to the invention an organoaluminium aluminum (TIBA) as a retarder, copolymers were obtained with low 1,2-vinyl content (Examples 1 to 4).

If you left that Retarder away (Example 5V), although the 1,2-vinyl content was still low, but gave non-inventive copolymers, the two glass transition temperatures exhibited.

In Example 6V was the molar ratio Al / Li with 0.6 outside the range of the invention (0.75 to 0.95: 1) to give a copolymer having two glass transition temperatures.

at Use of DBM instead of TIBA as retarder (Examples 7V to 13V) Copolymers with two glass transition temperatures were also obtained. Has been Mg in molar excess used (Examples 11V to 13V), increased beyond the 1,2-vinyl content significantly at about 30%.

Example 14:

It were submitted 2 kg of cyclohexane and 500 g of a solution 40 wt .-% of styrene and 60 wt .-% butadiene added. One gave with stirring one Initiator composition, as used for Examples 1 to 4 has been. Thereafter, it was kept at 70 ° C for 24 hours. Then broke the reaction is stopped by adding 10 ml of ethanol. The solids content the mixture was 20.3 wt .-%. The polymer was dried isolated as already described.

Of the Butadiene content of the polymer was 60 wt .-% and the 1,2-vinyl content in Butadienanteil was 13.2%, determined by NMR as described.

The Block copolymers possessed GPC analysis (gel permeation chromatography in tetrahydrofuran, calibration with polystyrene or polybutadiene standards) a monomodal distribution. The molecular weight was also determined by GPC and was 195,000 g / mol. The glass transition temperature of the obtained polymer was -21 ° C.

Example 15: Block Copolymer Homopolystyrene - S / B copolymer

It were submitted 2 kg of cyclohexane. While stirring, 300 was added g of styrene and 2.5 ml of s-BuLi solution and held at 40 ° C for 60 minutes. Thereafter, 3.5 ml of TIBA solution was added added, with a molar ratio Al / Li adjusted from 0.85. Subsequently, 500 g of a solution 40 wt .-% of styrene and 60 wt .-% butadiene added, and kept at 90 ° C for 24 hours. After all the reaction was quenched by the addition of 10 ml of ethanol. The solids content the mixture was 28.3 wt .-%. The polymer was isolated as described.

Of the Butadiene content of the polymer was 37.5 wt .-% and the 1,2-vinyl content in Butadienanteil was 12.8%, determined as described.

The Block copolymers possessed GPC analysis as previously described a monomodal distribution. The Molecular weights or block lengths were also determined by GPC and were for the homopolystyrene block 85,000 and for the styrene-butadiene copolymer block 141,000 g / mol. There were two Glass transitions Tg determined at -19 ° C and 102 ° C.

As Example 15 shows also block copolymers comprising a block of the styrene-butadiene copolymer according to the invention, produce.

Claims (12)

Process for the preparation of copolymers S / B from styrene monomers and diene monomers, wherein the copolymers have a 1,2-vinyl content in the diene portion of not more than 20%, by anionic polymerization, characterized in that without addition of Lewis bases and in the presence of an alkali metal organyl and an organoaluminum organolithium, wherein the molar ratio of aluminum / alkali metal is 0.75: 1 to 0.95: 1. Method according to claim 1, characterized in that that is used as styrene monomer styrene. Process according to claims 1 to 2, characterized that is used as diene monomer butadiene. Process according to claims 1 to 3, characterized that sec-butyllithium is used as alkali metal organyl. Process according to claims 1 to 4, characterized that is used as Aluminiumorganyl triisobutylaluminum. Process according to claims 1 to 5, characterized that the 1,2-vinyl content in the diene portion is 10 to 14%. Process according to claims 1 to 6, characterized that the molar ratio Aluminum / alkali metal 0.8: 1 to 0.9: 1. Process according to claims 1 to 7, characterized the copolymers have one and not several glass transition temperatures. Process according to claims 1 to 8 for the preparation of block copolymers containing at least one copolymer block S / B and at least one homopolymer block S of styrene monomer, or at least one homopolymer block B of diene monomer, characterized in that the copolymer block S / B according to the method of claims 1 to 8 and before or after styrene monomers to the Ho polymer block S, or diene monomers to the homopolymer block B, polymerized. Process according to claims 1 to 9, characterized the block copolymer has a block structure S-S / B, or S-S / B-S. Copolymers available according to the method according to claims 1 to 10th Block copolymers obtainable by the process according to claims 9 to 10th