CS217439B1 - Method of selective polymerization of butadiene from c4 fractions - Google Patents

Description

The invention relates to a process for the selective polymerization of butadiene from fractions. In particular, the invention relates to an economical and rational process for the selective polymerization of butadiene from olefin blends resulting from petroleum pyrolysis, using hydrocarbon-soluble bifunctional alkali metal initiators for polymerization. In this process, the microstructure of the polymers can be adjusted as desired from a high structure content of 1.4 to a high structure content of 1.2. The ends of the strings are functionalizable.

It is essential that the butadiene does not have to be separated from the mixtures prior to the polymerization and that the butadiene itself is converted into the polymer form during the polymerization. In this way, energy and labor associated with separation processes can be saved and the technology, by its properties, attractive for practical use. All other unsaturated hydrocarbons of this fraction remain unreacted and are available for further reactions, in particular for polymerization. On the other hand, it is also possible to produce alternative copolymers; whereas another embodiment of the invention is the mixed polymerization of butadiene with monomers which are mixed together with butadiene by the same initiator system,

It is known from the classical work of W. C. E. Higginson and N. S. Wooding (J. Chem. Soc., 1952, 760) that amidometallic systems, for example potassium amide, can polymerize styrene in liquid ammonia. G. Natta et al. Have investigated the use of substituted Be amides,

Al and Mg in the presence of transition metal halides such as TiCl 2 for the polymerization of ethylene and alphaCholines. Indian. (Milan), 42, 457, (1960); J. Poly, Sci. 48, 219 (1960)]. The polymerization of isoprene with lithium diethylamide has been reported by Vinogradov et al. [Polym. Sci. USSR, 4, 1568 (1963)], and in the same journal 4, 1528 (1963). A decade ago, Taban, Ottolenghi and Zilkha polymerized methyl methacrylate with the addition of Lithium Butyl and Diethylamine [Europ. Polym. J. 2: 199 (1966)].

It has been suggested in the patent literature that polymerization of pure diolefins with lithium amides is possible (U.S. 2,849,432). According to the teachings of this patent, the polymerization is carried out in an inert solvent or mass. However, lithium amide is very difficult to dissolve in conventional inert organic solvents and monomers. Since only dissolved lithium amide acts as a catalyst, the effective initiator dose is predetermined by the solubility of lithlumamide in the polymerization system. Generally, an excess of lithium amide is employed, which is fed into the reaction mixture by post-dissolution and replaces losses resulting from side reactions. In this way, the amount of catalyst is kept constant so that the polymer is reproducible, but the amount of catalyst is also fixed at a fixed value, so that the properties of the product also have a fixed and fixed value.

In DOS 2,355,941 it has been proposed to subject pure cohesive members to homopolymerization and polymerization in inert organic solvents via alkaloamides in the presence of solvating agents. The amount and type of solvating agent determines the amount of amide that can be dissolved in the polymerization batch. If the amide is in excess, then the dissolved amide consumed by side reactions can not be compensated by dissolving the corresponding amount. Thus, the active amount of catalyst is constant. By the amount and type of solvating agents, the concentration of the active initiator can be adjusted reproducibly and the molecular weight and microstructure of the polymer can be reproducibly changed. Since the solubility of the amide is also temperature dependent, the polymer may also be influenced by varying the reaction temperature during polymerization.

anionic polymerization has been reported in great detail about the same period by A.C. Angood, S.A. Rurlay and Pj. T. Taitem [J. Polym. Sci. 11,2777 (1973), Idem 13, 2,437 (1975) and Id 14,1655 (1976)], describing anionic polymerization initiated by lithium diethylamide in organic solvents. Isoprene and styrene were used as monomers. Lithium diethylamide has been shown to be an active initiator for the polymerization of: isoprene in hydrocarbons and a variety of polar solvents such as diethyl ether and tetrahydrofuran. The same initiator has the same dependence on the type of solvent in styrene polymerization. Thus, no polymerization in hydrocarbons or diethyl ether is observed, but rapid polymerization occurs in both tetrahydrofuran and 1,2-dimethoxyethane.

DOS 2,156,449 also discloses the use of a dialkyl-substituted alkali amide, dipropylamide-K, as an anionic initiator for the polymerization of 2-cyano-1,3-butadiene in polar solvents. The copolymers can be obtained by the addition of butadiene, isoprene or styrene, the catalyst being tetrahydrofuran or triethylemine.

most recently it has now been proposed to conjugate dienes optionally together with a vinylaromatic compound to polymerize to homopolymers and dlen copolymers in an inert organic solvent in the presence of a reaction product of a lithium, sodium or potassium organometallic compound with a primary monoamine or primary or secondary diamine catalyst (DOS 2,410,913) . Since the catalysts of the invention are to be partially soluble in hydrocarbons, they can be metered very well so that the molecular weight of the polymers can be adjusted within wide limits.

Generally, these diene polymers contain very few structural components 1,2. By adding polar solvents, the activity of these catalysts can be changed and the proportion of structures 1,2 increased. It should also be possible for polymers that are still polymerically active to react in solution with compounds that introduce reactive groups at the chain ends. When an agent such as ethylene oxide is used as such, OH-terminal products are obtained. Such products can be crosslinked chemically, for example by reaction with isocyanates. A disadvantage of the processes described so far in connection with the initiation systems used for the polymerization of monoolefins and diolefins is the following:

- only highly pure monomers are used to polymerize the monomers;

the alkaloamide initiators usually exhibit poor solubility in non-polar aliphatic hydrocarbons or too low solubility to obtain low molecular weight products;

monofunctional alkaloamide initiators with satisfactory solubility in nonpolar aliphatic hydrocarbons do not allow the formation of polymers having a functional group at each end of the chain. Alkaloamide initiators are in many cases not synthesized and characterized in the mass;

- The reproducible formation of polymers with molecular weights ranging from 1,000 to 5,000 and bifunctionality is clearly problematic.

The object of the invention is to eliminate the drawbacks of the known processes, i.e. to make the preparation of polybutadiene, butadiene copolymers and telechelic homopolymers or butadiene copolymers rational and economical. It is a further object of the present invention to carry out butadiene polymerization from undivided fractions, which are formed, in particular, by the pyrolysis of petroleum using specific bifunctional alkali metal diamide initiators either to polydienes with a high proportion of 1,4-structures or predominantly 1,2-structures. By admixing other anionic polymerizable monomers, it should be possible to prepare said block copolymers of butadiene type A-B-A or copolymers of butadiene with a random monomer distribution. The molecular weight of the homopolymers and copolymers should be selectable in any desired range. It is necessary to be able to introduce end groups into the polymers by reacting the obtained living polymers with special agents.

Process for the selective polymerization of butadiene from fractions to homopolymers or copolymers with or without functional groups and with a preselected molecular weight in the range of 1,000 to 300,000, with microstructures ranging from high structure content 1,4- to high structure content, 1,2 - in a homogeneous phase, in the presence of the lithium initiators according to the invention, the polymerization is carried out in the presence of the dilithiodiamide initiators of the general formula,

wherein R is an alkyl radical of 1 to 30, preferably 3 to 20 carbon atoms and n is 1 to 12, preferably 2 to 6, and at a temperature in the range of -75 to 150 ° C, preferably -10 to +100 ° C, optionally in the presence of non-polar solvents.

It is preferred that the polymerization process of the invention be carried out in the absence of a solvent at temperatures and pressures such that the monomer mixture is in the liquid phase.

The polymerization process is preferably carried out in the presence of diamide initiators selected from the group consisting of li, N'-di-thiuw-N, N'-dibutyl-tylenediamide,

N, N'-Dithithium-M, N'-Dectylethylenediamide,

N, M'-dilithium-N, K'-bisdodecylethylenediamide a

Μ, N'-Dithithium-N, K'-Dittracetylethylenediamide.

In order to obtain block copolymers of ABA wherein B is a polybutadiene block or static copolymers, it is possible to carry out the process of the invention in the presence of an anionically copolymerizable monomer, preferably isoprene, styrene, alpha-methylstyrene or acrylonitrile and the like. with electrophilic compounds, in particular COg, alkylene oxides, or lactones, for low-molecular-weight polymers with terminal functional groups.

The polymer products prepared by the process of the invention have the same properties as the polymers prepared using pure butadiene 1.3. This makes it clear that the advantage of saving separation and cleaning operations over the conventional process using pure butadiene 1.3.

The polymerization can be carried out in a manner known per se. It is a bulk polymerization or, depending on the butadiene concentration in the fraction, the addition of non-polar solvents such as benzene, toluene, n-hexane, cyclohexane or gasoline fractions is also used. Preferably, the process is carried out without the addition of a non-polar solvent as the polymerization medium, with the polymerizable fraction components acting as the diluent. A modifier which causes such an increase may optionally be used to increase the 1,2-structure content of the polybutadiene.

Suitable modifiers are, for example, polar compounds such as ether amines or alcoholates.

The polymerization time is generally 3 to 10 hours. The amount of initiator to be used is determined by the desired molecular weight of the polymer since it is a stoichiometric polymerization. Both high molecular weight homopolymers or copolymers, e.g. 200,000, as well as low molecular weight homopolymers or copolymers, e.g.

The process according to the invention is characterized in that it eliminates the disadvantages of known processes, such as the need to separate butadiene from the fractions prior to polymerization.

It is further characterized by eliminating the disadvantages of lower solubility of the initiators in non-polar solvents, the unavailability of initiator systems for ether-free media, the unrepeatable and complicated structure and characteristics of the initiator, the time-consuming initiator-forming reactions and limited molecular weight adjustability of polymerization. products. It is further characterized in that the addition of additional solvating agents of different nature and amount as modifier enables the polydiene microstructure to be adjusted in a wide range, and thus it is possible to specifically obtain polymers for special applications.

The possibility of polymerization in the absence of ether means suppression of disintegration reactions so that it can be obtained by functionalizing active polymers with known agents for the functionalization of telechelic polymers. Despite the prior art, it is surprising that by using the fraction as the butadiene source, the above effects can be achieved.

In order to illustrate the process according to the invention, specific examples are given below, but are not intended to limit the invention in any way.

Examples 1 to 6

About 200 to 25 mmol of N, N'-dilithium-N, N'-dibutylethylenediamide, N, M-dilithium-N, N'-dioctylethylenediamide or N, NYdilithium-N, N'-nitetradecylethylenediamide are dissolved in 200 ml of heptane. and introduced into a glass autoclave containing 200 ml of a C1-fraction containing 35% butadiene corresponding to 45.6 g butadiene. The homogeneous reaction mixture was stirred at room temperature for 24 h or at 70 ° C for 7 h. After completion of the polymerization and corresponding further processing, the yield of butadiene obtained is determined. It can be seen as well as the microstructure obtained by infrared spectroscopy from the attached table.

Ex. C. Initiator mmol Reaction time h Temperature Noc: 2 ° C Yield cis % Micro structure trance % 1,2- % β % 1 22.65 24 24 28.4 65 38 53 9 2 22.7 7 70 44.5 100 ALIGN! 37 55 8 3 21.3 24 24 34.1 75 40 42 18 4 24.55 7 70 45 100 ALIGN! 41 47 12 5 21.4 24 24 36.5 80 32 48 20 May 6 23.8 7 70 45 100 ALIGN! 35 50 15 Dec

In Examples 1 and 2, N, N * -dilithium-N, N'-dibutylethylenediamide was used, in Examples 3 and 4, N, N'-diithiamine-N, N'-dioctyl-ethylenediamines (iu, in Examples 5 and 6). Μ, Ν'-dilithiamine-N, N'-di tetradecylethylenediamide was used.

Example 7

To 63.2 mmol of N, N'-dilithium-N, N'-dibutylethylenedimide initiator in 200 mL of tetrahydrofuran was added 400 mL of the above fraction. After 5 hours, the polymerization at 50 ° C was discontinued. The polymerization yield was almost 100 SS. The analysis resulted in the following microstructure: 87 SS 1,2- and 13% 1,4-trans units.

Example 8

The autoclave was charged with 48.6 mmol of N, K, N-di-lithium-K, N, N-dibutylethylenediemide, sealed into a thin-walled glass vial, along with a 300 ml fraction. After the initiator was released, the reaction mixture was stirred at 70 ° C for 6 hours and then 50 ml of ethylene oxide was added with cooling and warmed to room temperature. The polymer yield corresponds to nearly 100 SS. The product has the functionality P = 1.93 '. The microstructure of this polymer is 47% 1,4-eis, 43 SS 1,4-trans and 10 SS 1,2-butadiene. The relative mean molecular weight was 880 calculated for 1400.

Example 9

Analogously to Example 8, instead of ethylene oxide, propylene oxide was used to functionalize the polybutadiene and the microstructure obtained was identical to that of Example 8.

The functionality of the polymer was determined to be F = 1.89 and the average molecular weight was 2150.

Example i

To a 200 ml heptane solution of 33.2 mmol of N, S'-dilithium-N, N'-dibutylethylenediamide initiator was added a mixture of 45.6 g of butadiene contained in the 200 ml fraction and 4.5 g of styrene in 200 ml of heptane. The reaction mixture was stirred at 70 ° C in an autoclave for 10 hours. At 100 SS yield, a butadiene-styrene copolymer is formed. The product has a styrene content of 10 SS.

object of the invention

Claims (3)

A process for the selective polymerization of butadiene from fractions into homopolymers or copolymers with or without functional groups and with a preselected molecular weight in the range of 1,000 to 300,000 with microstructures ranging from a high content of 1,4- to a high content of 1,2 - in homogeneous phase in the presence of lithium initiators, characterized in that the polymerization is carried out in the presence of dilithium diamide initiators of the general formula wherein R is an alkyl radical of 1 to 30, preferably 3 to 20 carbon atoms and n is 1 to 12, preferably 2 to 6 and at a temperature in the range of -75 to 150 ° C, preferably -10 to +100 ° C, optionally in the presence of non-polar solvents. 2. The process according to claim 1, wherein the polymerization is carried out in the absence of a solvent at temperatures and pressures such that the monomer mixture is in the liquid phase. 3. A process according to any one of claims 1 to 4, wherein the polymerization is carried out in the presence of a diamide initiator selected from the group consisting of N, N'-dithithium-N, H'-dibutylethylenediamide, N, N'-dithithium-N, N'-dioctylethylenediamide, N, N'-dilithium-N, N'-bi-dodecylethylenediamide and N, N'-dilithium-N, N'-ditetradecylethylenediamide.