WO2003029325A1

WO2003029325A1 - Method for producing aliphatic polycarbonates

Info

Publication number: WO2003029325A1
Application number: PCT/EP2002/010406
Authority: WO
Inventors: Johannes Heinemann; Gerrit Luinstra; Edward Bohres
Original assignee: Basf Aktiengesellschaft
Priority date: 2001-09-27
Filing date: 2002-09-17
Publication date: 2003-04-10
Also published as: WO2003029240A1; DE10147712A1

Abstract

The invention relates to a method for producing high-molecular aliphatic polycarbonates having the following properties: the average molecular weight Mw ranges from 30,000 to 1,000,000, and; the content of cyclic carbonates and polyethers equals, in total, a maximum of 5 wt. %. Said polycarbonates are produced by polymerizing carbon dioxide with at least one epoxide while using at least one catalyst selected from the group consisting of zinc carboxylates and multi-metal cyanide compounds. The invention is characterized in that the catalyst is introduced in anhydrous form, and the catalyst is firstly brought into contact with at least a partial quantity of the carbon dioxide before the epoxide is added.

Description

Process for the production of aliphatic polycarbonates

description

The invention relates to a process for the production of high molecular weight aliphatic polycarbonates with the following properties

10 - the weight average molecular weight M _w , determined by

Gel permeation chromatography using hexafluoroisopropanol as eluent and polymethyl methacrylate standards is 30,000 to 1,000,000.

15 - the content of cyclic carbonates and polyethers taken together is a maximum of 5% by weight,

by polymerizing carbon dioxide with at least one epoxide of the general formula 1-20

(1)

/ \ / \

25

in which the radicals R independently of one another represent hydrogen, halogen, -N0, -CN, -COOR or a hydrocarbon group with 1 to 30 20 C atoms, which may be substituted,

using at least one catalyst selected from the group consisting of zinc carboxylates and multimetal cyanide compounds.

35

The invention also relates to aliphatic polycarbonates obtainable by this process and to thermoplastic molding compositions which contain these polycarbonates. Finally, the invention relates to the use of these thermoplastic molding compositions

40 for the production of moldings, foils, films, coatings and fibers, and also these moldings, foils, films, coatings and fibers from the thermoplastic molding compositions.

Copolymers of epoxides such as ethylene oxide (abbreviated EO) or 5 propylene oxide (abbreviated PO) and carbon dioxide (C0 ₂ ) and processes for their production are known. The copolymers are called aliphatic polycarbonates or aliphatic polyether carbonates.

Common catalysts for these polymerization reactions are in particular organic zinc compounds such as Zinc carboxylates, or cyanide complexes with two or more metal atoms, e.g. Double metal cyanide complexes.

DE-A 197 37 547 describes a process for the preparation of polyalkylene carbonates using a catalyst which is prepared from zinc oxide or other inorganic zinc compounds and a mixture of two aliphatic or aromatic dicarboxylic acids. First the epoxide and then CO _{2 are} metered into the reactor, ie the catalyst first comes into contact with the epoxy before CO _{2 is} added.

The US-A 5 026 676 discloses a process for the copolymerization of CO ₂ and epoxides in the presence of zinc carboxylate catalysts, the epoxy and then the CO _{2 being added} to the reactor.

ÜS-A 4 943 677 describes a similar process in which the zinc carboxylate catalyst is placed in the reactor and heated in a stream of nitrogen for several hours before the epoxide and then the CO _{2 are} added.

A corresponding method is disclosed in US Pat. No. 4,783,445, in which a zinc dicarboxylic acid ester is used as catalyst. Again, the epoxy is first added to the catalyst before C0 _{2 is} injected.

The US-A 5 041 469 describes the copolymerization of epoxy and C0 in methylene chloride of the solvent, wherein epoxy, C0 ₂ and the zinc carboxylate catalyst are presented together.

The three WO-A documents 01/04178, 01/04179 and 01/04183 describe a process for the preparation of polyoxyalkylenes from epoxides in the presence of metal cyanide complexes as a catalyst, it also being possible to use C0 as well. The catalyst and epoxide are initially introduced and left to activate the catalyst. Then the reaction starts and further epoxy is added.

EP-A 222 453 discloses a process for the production of polycarbonates from epoxides and CO ₂ using a

Catalyst system of double metal cyanide compounds and a cocatalyst such as zinc sulfate. The polymerization is initiated by bringing a small part of the epoxide into contact with the catalyst system. Only then the remaining amount of epoxy and the C0 are metered in simultaneously, the copolymerization taking place (p. 3, lines 53-57 and examples).

US Pat. No. 4,500,704 describes a process for the preparation of epoxy-CO ₂ copolymers in which double metal cyanide complexes are used as catalysts. Again, before the actual copolymerization, the double metal cyanide catalyst is first activated by contacting it with the epoxy for up to 45 minutes. Only then is C0 ₂ pressed on and copolymerized (column 5, lines 46-50). According to Example 1, the PO-CO ₂ copolymer obtained has a number average molecular weight (molar mass) M _n of 23,000.

The prior art methods have at least one of the following disadvantages:

The activity of the catalysts is insufficient, i.e. so few grams of polymer are produced per gram of catalyst used that the process is uneconomical.

The polymerization times are four to 84 hours so long that the process is uneconomical.

The molecular weights of the polycarbonates obtained are so low that their properties of use (in particular the mechanical properties) are at an unacceptably low level. That the polycarbonates are hardly suitable for the production of molding compounds or molded parts.

In addition to the desired polycarbonates, undesirable by-products are also formed, in particular epoxy homopolymers (i.e. polyethers) and cyclic (mostly monomeric) carbonates. The by-products reduce the yield of polycarbonate and may have to be separated from the main product at great expense. In addition, they significantly deteriorate the mechanical properties of the polymer mixture obtained. Cyclic carbonates, for example, significantly lower the glass transition temperature of the polycarbonate, which prevents certain possible uses.

The possible reaction products can be shown schematically using the example of the reaction of propylene oxide and C0 as follows: alternating polycarbonate I

Polyether carbonate II

Polyether III

Propylene carbonate IV

The indices n and k are integers greater than or equal to 1 and indicate the number of repetition units.

The polyethers III and the cyclic carbonates IV are undesirable by-products.

The polycarbonates I and the polyether carbonates II are the desired process products and are referred to collectively as "polycarbonates". “Polycarbonates” in the sense of the invention accordingly include both strictly alternating polycarbonates I and polycarbonates II with polyether segments (polyether carbonates). The task was to remedy the disadvantages described. In particular, the task was to provide a process for the production of polycarbonates from epoxides and C0, in which the catalyst activity (mass of polymer obtained per mass unit of catalyst) is improved.

Another object was to provide an economical process with shorter polymerization times, in particular times of up to four hours.

In addition, the process should provide higher molecular weight polycarbonates than the prior art processes. The polycarbonates obtainable by the process should have better mechanical properties.

Finally, a process should be found that produces fewer undesirable by-products. In particular, the content of interfering polyether homopolymer III and in particular of cyclic carbonates IV should be significantly reduced.

Accordingly, the process defined at the outset was found. It is characterized in that the catalyst is used in anhydrous form and that the catalyst is first brought into contact with at least a portion of the carbon dioxide before the epoxy is added.

In addition, the aliphatic polycarbonates, thermoplastic molding compositions mentioned above, the use of the molding compositions and the objects produced therefrom were found, as mentioned at the beginning.

Preferred embodiments of the invention can be found in the subclaims.

The weight average molecular weight M _{w of} the polycarbonates is determined by means of gel permeation chromatography (GPC, also referred to as size exclusion chromatography (SEC)) using hexafluoroisopropanol (HFiP) as eluent and calibration with polymethyl methacrylate (PMMA) standards. You can work as follows, for example: Detector: ERC 7510 differential refractometer from ERC; Columns: HFiP Gel guard column and HFiP Gel linear separation column, both from Polymer Laboratories; Calibration with narrowly distributed PMMA standards with molecular weights M from 505 to 2,740,000 from PSS. The polycarbonates produced by the process according to the invention have a weight-average molecular weight M _w of 30,000 to 1,000,000. Molecular weights M _w are preferably 200,000 to 500,000 for propylene oxide as epoxide and 30,000 to 300,000 for ethylene oxide as epoxide.

The cyclic carbonate content of the polycarbonates, e.g. cyclic carbonate monomers IV, and on polyethers, e.g. Polyether homopolymers III (see diagram above), together amounts to a maximum of 5% by weight. That the sum of the by-products cyclic carbonates and polyethers is a maximum of 5% by weight.

The content of cyclic carbonates and polyethers can be determined in a known manner. Nuclear magnetic resonance (NMR) is usually used for this, in particular ^ H NMR. An ^X H-NMR spectrum of the process - product polycarbonate indicates by appropriate bands (peaks) whether cyclic carbonates and / or polyethers are present in the polycarbonate. Their amount can be determined in a known manner by quantitative analysis of the spectra.

The following can be said about the process materials:

Carbon dioxide C0 ₂ is inexpensive as a component of the air and is available almost indefinitely.

The epoxides used have the general formula 1

R 0 R

on. The radicals R here independently of one another denote hydrogen, halogen, nitro group -N0 ₂ , cyano group -CN, ester group -COOR or a hydrocarbon group with 1 to 20 C atoms, which can be substituted.

Such hydrocarbon groups are especially Cι_o -alkyl, C _{_2-20} -alkenyl, C ₃ -C ₂₀ cycloalkyl, C ₆ _ ₁₈ aryl, and C ₇ _ ₀ arylalkyl. In this case, two radicals R, if they are attached to different C atoms of the epoxy group

located, bridged together and thus form a C_ o-cycloalkylene group.

The following groups are particularly suitable as substituents with which the C ₂ O hydrocarbon group can be substituted: halogen, cyano, nitro, thioalkyl, tert-amino, alkoxy, aryloxy, arylalkyloxy, carbonyldioxyalkyl, carbonyldioxyaryl, carbonyldioxyarylalkyl, alkoxycarbonyl, aryloxycarbonyl , Arylalkyloxycarbonyl, alkylcarbonyl, arylcarbonyl, arylalkylcarbonyl, alkylsulfinyl, arylsulfinyl, arylalkylsulfinyl, alkylsulfonyl, arylsulfonyl and arylalkylsulfonyl.

The epoxide used is preferably ethylene oxide, propylene oxide, butylene oxide (1-butene oxide, BuO), cyclopentene oxide, cyclohexene oxide (CHO), cycloheptene oxide, 2,3-epoxypropylphenyl ether, epichlorohydrin, epibromohydrin, i-butene oxide (IBO), or acrylic oxides. Ethylene oxide (EO), propylene oxide (PO), butylene oxide, cyclopentene oxide, cyclohexene oxide or i-butene oxide are particularly preferably used. Very particularly preferably ethylene oxide and propylene oxide. It is understood that mixtures of the aforementioned epoxides can also be used.

When using C0 ₂ and two or more epoxies, polycarbonate terpolymers are formed. If, for example, the epoxides ethylene oxide and cyclohexene oxide are used in addition to C0 ₂ , C0 / E0 / cyclohexenoxide terpolymers are formed. Examples of suitable mixtures of two epoxides are: EO and PO (a C0 ₂ / Eθ / PO terpolymer is formed), EO and cyclene hexene oxide, PO and cyclohexene oxide, i-butene oxide and EO or PO, butylene oxide and EO or PO, etc.

The two or more epoxides can be added as a mixture or separately.

The C0 ₂ : epoxy ratio can be varied within wide limits. C0 is usually used in excess, ie more than 1 mol of C0 per 1 mol of epoxide.

The catalyst is selected from the group consisting of zinc carboxylates and multimetal cyanide compounds. Zinc carboxylates are zinc salts of carboxylic acids. Particularly suitable carboxylic acids are dicarboxylic acids, especially aliphatic dicarboxylic acids. Adipic acid and glutaric acid are particularly suitable. Accordingly, zinc adipate and zinc glutarate are very particularly suitable zinc carboxylates.

The zinc carboxylates are prepared in a manner known per se from zinc compounds (inorganic such as e.g. zinc oxide, zinc hydroxide, zinc halide or organic such as e.g. zinc acetate, zinc propionate) and the carboxylic acids corresponding to the carboxylate residue. Instead of the carboxylic acids, carboxylic acid derivatives such as e.g. Use carboxylic acid anhydrides or lower carboxylic acid esters such as acetates or propionates. Corresponding production processes for zinc carboxylates are e.g. in the documents US-A 4 783 445 and DE-A 197 37 547.

Multimetal cyanide compounds are complexes which contain at least two metals complexly coordinated with cyanide ions per formula unit, and possibly further ligands. With exactly two metals coordinated with cyanide per formula unit, one also speaks of double metal cyanide complexes (DMC).

Suitable multimetal cyanide compounds are known and are described in the following A documents: US 3,278,457, US 3,278,458, US 3,278,459, US 3,427,256, US 3,427,334, US 3,404,109, US

3,829,505, US 3,941,849, EP 283.148, EP 385.619, EP 654.302, EP 659.798, EP 665.254, EP 743.093, EP 755.716, US 4,843,054, US 4,877,906, US 5,158,922, US 5,426,081, US 5,470,813, US 5,482,908, US 5,498,583, US 5,523,386, US 5,525,565, US 5,545,601, JP 7,308,583, JP 6,248,068, JP 4,351,632 and US 5,545,601.

Multimetal cyanide complexes are also e.g. in the documents DD-A 148 957, EP-A 862 947, EP-A 654 302, EP-A 700 949, WO-A 97/40086, WO-A 98/16310, EP-A 222 453, EP-A 90 444, EP-A 90 445, WO-A 01/04177, WO-A 01/04181, WO-A 01/04182, WO-A 01/03830, DE-A 199 53 546.

Particularly suitable multimetal cyanide catalysts are double metal cyanide compounds, in particular those of the formula 2

M ¹ _a [M ² (CN) _b A _c ] _d • f Mi _g n • h H ₂ 0 • e L • k P (2)

The letters M, A, X, L and P stand for atoms or groups of atoms. CN and H ₂ 0 are cyanide and water. The superscript indices ¹ and ² are used to distinguish between the different M. Indices _a , t _> , _{C / <} ι, g, n are stoichiometric indices and the letters f, h, e and k are mole numbers.

In the general formula ^' 2 mean

M ¹ at least one metal ion selected from the group comprising Zn ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Ni ²⁺ , Mn ²⁺ , Sn ⁺ , Pb ²⁺ , Mo ⁺ , Mo6 + , A13 +, v ⁺ , V5 ⁺ , Sr ²⁺ , W ⁴⁺ , W ⁶⁺ , Cr ²⁺ , Cr ³⁺ , Cd ²⁺ , La ³⁺ , Ce ³⁺ , Ce ⁴⁺ , Eu ³⁺ , Mg ²⁺ , Ti ³⁺ , Ti ⁴⁺ , Ag ⁺ , Rh ²⁺ , Ru ⁺ , Ru ³⁺ ,

M ² at least one metal ion selected from the group comprising Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Mn ²⁺ , Mn ³⁺ , V ⁺ , V ⁵⁺ , Cr ²⁺ , Cr ³⁺ , Rh ³ +, Ru ⁺ , Ir3 +,

where M ¹ and M ^{2 can be the} same or different,

A at least one anion selected from the group containing halide, hydroxide, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate, nitrate, nitrosyl, phosphate, dihydrogen phosphate, hydrogen phosphate,

X at least one anion selected from the group comprising halide, hydroxide, sulfate, carbonate, hydrogen carbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate, nitrate,

where A and X can be the same or different,

L at least one water-miscible ligand selected from the group comprising alcohols, aldehydes, ketones, ethers, polyethers, esters, polyesters, polycarbonates, ureas, amides, nitriles, sulfides, amines, ligands with pyridine nitrogen, phosphides, phosphites, phosphines , Phosphonates, phosphates,

P at least one organic additive selected from the group comprising polyethers, polyesters, polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycol glycidyl ethers, polyacrylamide, poly (acrylamide-co-acrylic acid), polyacrylic acid, poly (acrylamide-co-maleic acid), polyacrylonitrile, polyalkyl acrylates , Polyalkyl methacrylates, polyvinyl methether, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl alcohol, poly-N-vinyl pyrrolidone, poly (N-vinyl pyrrolodone-co-acrylic acid), polyvinyl methyl ketone, poly (4-vinylphenol), poly (acrylic acid-co-sty - rol), oxazoline polymers, polyalkyleneimines, maleic acid, maleic anhydride copolymer, hydroxyethyl cellulose, polyacetates, ionic surface-active and surface-active Compounds, bile acid and the salts, esters and amides of bile acid, carboxylic acid esters, polyhydric alcohols, glycosides,

where a, b, d, g and n are whole or fractional numbers greater than zero, and

where c, f, h, e and k are whole or fractional numbers greater than or equal to zero, and

where a, b, c, d, g and n are chosen so that the electro-neutrality of the cyanide compound M ¹ [M ² (CN) A] or the compound M ^X X is ensured.

Formate, acetate and propionate are preferred as carboxylate groups A and X, respectively.

The multimetal cyanide compounds can be crystalline or amorphous. For k equal to zero, the multimetal cyanide compounds are generally crystalline or predominantly crystalline. For k greater than zero, they are crystalline in general, partially crystalline or amorphous WE ^~ sentliehen.

The primary particles of the multimetal cyanide compounds preferably have a crystalline structure and a content of platelet-shaped particles of more than 30% by weight, based on the total weight of the multimetal cyanide compound. The platelet shape of the particles leads to an increase in the proportion of catalytically active surface, based on the total surface, and thus an increase in the mass-specific activity.

The term "primary particle" is understood to mean the individual crystallite as it e.g. can be seen on the scanning electron micrographs. These primary particles can then assemble to form agglomerates, the so-called secondary particles.

The term "platelet-shaped" is understood to mean that the length and width of the primary particles are at least three times greater than the thickness of these particles.

The term "crystalline structure" is understood to mean that not only a short-range order, such as an arrangement of, for example, 6 carbon atoms around a metal atom, but also a long-range order exists in the solid state, that is to say an ever-recurring unit, too referred to as a unit cell, define from which the entire solid can be built. If a solid is crystalline, this is expressed, among other things in the X-ray diffractogram. In the case of a crystalline substance, the X-ray diffractogram shows "sharp" reflections, the intensities of which are clearly, ie at least three times, greater than that of the background.

Instead of platelet-shaped, the primary particles can also e.g. be bar-shaped, cube-shaped or spherical.

Preferred multimetal cyanide compounds contain:

as M ¹ at least one metal ion selected from the group comprising Zn ²⁺ , Fe ²⁺ , Fe ³⁺ ,

as M ² at least one metal ion selected from the group comprising Co ²⁺ , Fe ²⁺ , Fe ³⁺ ,

as A cyanide anion,

as X at least one anion selected from the group containing formate, acetate, propionate,

as L at least one water-miscible ligand selected from the group containing tert-butanol, monoethylene glycol dimethyl ether (Gly e)

as P polyether.

Multimetal cyanide compounds of the above formula 2 in which k and e are greater than zero are particularly preferred. These compounds contain the multimetal cyanide, at least one ligand L and at least one organic additive P.

Also particularly preferred are multimetal cyanide compounds of the above formula 2, in which k is zero and optionally e is zero. These compounds contain no organic additive P and optionally no ligand L.

Multimetal cyanide compounds with k and e equal to zero, in which X is selected from the group consisting of formate, acetate and propionate, are very particularly preferred. These compounds contain no organic additive P and no ligand L. Details can be found in WO-A 99/16775. In this embodiment, crystalline double metal cyanide catalysts are preferred; and double metal cyanide catalysts which are crystalline and platelet-shaped (see WO-A 00/74845). Also particularly preferred are multimetal cyanide compounds of the formula 2 in which f, e and k are not equal to zero. Ie these compounds contain the metal salt M ^ - _g X _n , a ligand L and organic additives P. ' See WO-A 98/06312. 5

The preparation of the multimetal cyanide compounds is e.g. described in WO-A 00/74843, WO-A 00/74844, WO-A 00/74845, EP-A 862 947, WO-A 99/16775, WO-A 98/06312 and US-A 5 158 922. Usually an aqueous solution of the metal salt is combined

1.0 M ⁱ gX _n with an aqueous solution of the cyanometalate H _a M ² (CN) _b A _c , where H is hydrogen, alkali metal, alkaline earth metal or ammonium. The metal salt solution and / or the cyanometalate solution can contain the water-miscible ligand L and / or the organic additive P. After the unification of the

15 solutions, ligand L and / or additive P may be added. In catalyst production it is advantageous to stir vigorously, e.g. with high speed stirrer. The precipitate is separated off in a conventional manner and, if necessary, dried.

20 The starting material cyanometalate H _a M ² (CN) _b A _c with H equal to hydrogen (so-called cyanometalate hydrogen acids) can be produced from the corresponding alkali or alkaline earth metal cyanometalates, for example via acidic ion exchangers, see for example WO-A 99 / 16,775th

25 As in the older, unpublished DE application Az. 10009568.2, one can also first produce an inactive catalyst phase and then convert it into an active phase by recrystallization.

30 Those skilled in the art will find further details of the production process of the multimetal cyanide compounds in the writings of the three preceding paragraphs.

A compound which can be obtained by reacting aqueous hexacyanocobaltoic acid H ₃ [Co (CN) g] with aqueous zinc acetate solution is very particularly preferably used as the multimetal cyanide compound. This reaction can be carried out, for example, under the conditions specified in the examples, see, for example, the manufacturing instructions there. 0

The following should be said about the process according to the invention for the production of high molecular weight aliphatic polycarbonates by polymerizing C0 with at least one epoxide (the reaction conditions mentioned below apply in the same way to 5 zinc carboxylate and multimetal cyanide catalysts, unless stated otherwise): According to the invention, the catalyst is used in anhydrous form. This means that the catalyst - apart from the chemically bound water (for example h mol crystal water in the general formula 2 above) - contains no water or only insignificant traces of water, in particular no water which adheres to the surface or is physically enclosed in cavities.

In a preferred embodiment, the catalyst is therefore made anhydrous before it is used. This is particularly preferably done by heating the catalyst in a stream of inert gas or in vacuo until it is free of water before starting the polymerization. Nitrogen, argon or other customary inert gases are usually used as the inert gas. The temperature up to which the catalyst is heated is usually 80 to 130 ° C. The duration of the heating is usually 20 to 300 minutes. Typical values are 2 hours at 120 ° C for zinc carboxylate and 4 hours at 130 ° C for multimetal cyanide catalysts.

The catalyst can e.g. Place in the polymerization reactor, make anhydrous in the inert gas stream (bake out) and - if necessary after cooling - carry out the polymerization in the same reactor, i.e. anhydrous the catalyst and polymerization can be easily done in the same vessel.

However, the catalyst can also be made anhydrous by heating in vacuo or other suitable drying methods.

In a preferred embodiment, the anhydrous catalyst is then dissolved or dispersed (suspended or emulsified) in an inert reaction medium before the polymerization is started. The dissolving or dispersing can take place with stirring.

Suitable as an inert reaction medium are all substances which do not adversely affect the catalyst activity, in particular aromatic hydrocarbons such as toluene, xylenes, benzene, also aliphatic hydrocarbons such as hexane, cyclohexane, and halogenated hydrocarbons such as dichloromethane, chloroform, isobutyl chloride. Also suitable are ethers such as diethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether (diglyme), dioxane, and nitro compounds such as nitromethane. Toluene is preferably used. The inert medium can be pressed, for example, as such or preferably with a gas stream into the polymerization reactor, it being possible to use an inert gas such as nitrogen or the reactant C0 ₂ as the gas.

The catalyst is preferably first placed in the reactor, made anhydrous by heating in an inert gas stream, allowed to cool if necessary, and the inert reaction medium is forced into the reactor with gas while stirring.

Based on the catalyst solution or dispersion (sum of catalyst and reaction medium), the catalyst concentration is preferably 0.01 to 20, in particular 0.1 to 10% by weight. Based on the sum of epoxy and inert reaction medium, the catalyst concentration is preferably 0.01 to 10, particularly preferably 0.1 to 1% by weight.

In another, likewise preferred embodiment, one works without an inert reaction medium.

According to the invention, the catalyst is first brought into contact with at least a portion of the CO before the epoxide is added. Here, “with at least a partial amount” means that, before adding the epoxy, either a partial amount of the total amount of CO _{2 used is} added, or the total amount of CO _{2 is} already added.

Preferably, only a subset of the CO _{2 is added} , and this subset is particularly preferably 20 to 80, in particular 55 to 65% by weight of the total CO amount.

Usually you add the C0 ₂ as a gas and the amount of C0 ₂ is - depending on the temperature - adjusted via the C0 gas pressure. At room temperature (23 ° C) in the reactor of the C0 ₂ pressure amounts prior to the addition of the epoxide (hereinafter called C0-form), which is the preferred C0 ₂ -Teilmenge corresponds, when using the zinc carboxylate catalysts 5 to 70, particularly 10 to 30 bar, and when using the multimetal cyanide catalysts 5 to 70, in particular 10 to 50 bar. Typical values for the CO ₂ admission pressure are 15 bar for zinc carboxylate catalysts and 50 bar for multimetal cyanide catalysts, both at 23 ° C.

All pressure specifications are absolute prints. The CO ₂ pre-pressure can be set discontinuously at one time or divided into several steps, or also set continuously over a certain period of time linearly or following a linear exponential or stepwise gradient. When choosing the C0 admission pressure, the pressure increase in the reactor due to the subsequent heating of the reactor to the reactor temperature must be taken into account. The C0 ₂ admission pressure (eg at 23 ° C) should be selected so that the desired C0 _{2 end} pressure at the reaction temperature (eg 80 ° C) is not exceeded.

The catalyst is generally brought into contact with CO at temperatures of 20 to 80 ° C., preferably 20 to 40 ° C. It is particularly preferred to work at room temperature (23 ° C.). The duration of the contacting of catalyst and CO ₂ is dependent on the reactor volume and is usually 30 seconds to 120 minutes.

As a rule, the catalyst or the solution or dispersion of the catalyst is stirred in the inert reaction medium while being brought into contact with the CO.

Only after the catalyst has been brought into contact with CO ₂ is the epoxide added to the reactor. The epoxy is usually pressed as such or preferably with a small amount of inert gas or CO ₂ into the reactor.

The epoxide is usually added with stirring and can be carried out all at once (in particular in the case of a small reactor volume) or continuously over a period of generally 1 to 100 min, preferably 10 to 40 min, the addition being constant over time or a gradient can follow the example can be ascending or descending, linear, exponential or gradual.

The temperature when the epoxide is added is generally 20 to 100, preferably 20 to 70 ° C. In particular, you can a) either add the epoxy at low temperature (eg room temperature 23 ° C) and then adjust the reactor to the reaction temperature T _R (eg 80 ° C) or b) conversely, first set the reactor to the reaction temperature T _R and then add the epoxy. Variant a) is preferred.

The reactor is accordingly brought to the reaction temperature T _R before or - preferably - after the addition of the epoxide. The reaction temperature is usually set at 30 to 180, in particular 50 to 130 ° C. This is usually done by ^heating the reactor with stirring. The reaction temperature is usually 40 to 120, preferably 60 to 90 ° C. Typical values are 80 ° C for zinc carboxylate and 65 to 80 ° C for multimetal cyanide catalysts. After the reaction temperature has been reached, the remaining amount of C0 _{2 is added} to the reactor, preferably with stirring, unless the total amount of C0 has already been added when the catalyst is brought into contact with C0 ₂ (see above). Customarily as presents to the C0 ₂ amount again recorded the C0 ₂ gas pressure. C0 is preferably added until the CO pressure (hereinafter referred to as CO final pressure) is 1 to 200, preferably 10 to 100 bar when using zinc carboxylate catalysts and 20 to 200, preferably 80 to 100, when using multimetal cyanide catalysts bar. Typical values for the CO _{2 end} pressure are 20 to 100 bar for zinc carboxylate and 100 bar for multimetal cyanide catalysts.

All pressure specifications are absolute prints. In this process - step added C0 ₂ amount (C0 ₂ -Enddruck) naturally depends also on the C0 ₂ -Teilmenge that had been previously added. From the C0 ₂ pressures and reaction temperatures mentioned it follows that the C0 can be present in the reactor in the supercritical state (ie liquid). The C0 _{2 is} in the supercritical state, especially at C0 _{2 end} pressures above 74 bar and reaction temperatures T _R above 31 ° C. In contrast to conventional chemical reactions in critical C0 ₂ , the C0 ₂ in the present process is not only a reaction medium, but also a feedstock (reaction partner) and reaction medium.

The final C0 pressure can be set discontinuously at once or continuously as described for the C0 ₂ pre-pressure.

-Once the final C0 pressure has been reached, this can be maintained by re-metering the used C0 ₂ , if necessary. If no C0 is replenished, the C0 ₂ pressure generally drops during the reaction due to consumption of C0 ₂ . This is also possible.

The time to complete the polymerization reaction is usually 60 to 500 min, preferably 120 to 300 min. A typical value for this post-reaction time is 3 to 4 hours. The reaction temperature is usually kept constant; however, they can also be raised or lowered depending on the progress of the reaction.

The quantitative ratios used in the process C0 ₂ : epoxy depend in a known manner on the desired properties of the polymer. Usually the ratio (weight ratio) of total amount of CO ₂ : total amount of epoxy is 1: 1 to 2: 1. In a preferred embodiment, all of the aforementioned process steps are carried out with the exclusion of water: not only the catalyst, but also the inert reaction medium, the CO ₂ and the epoxide are anhydrous or are rendered anhydrous in the customary manner.

After the polymerization reaction has subsided, the contents of the reactor are worked up onto the polycarbonate. This is done in a known manner. As a rule, the reactor is allowed to cool with stirring, the pressure is equalized with the surroundings (ventilation of the reactor), and the polycarbonate polymer precipitates by placing the reactor contents in a suitable precipitation medium.

Usually alcohols such as methanol, ethanol, propanol or ketones such as acetone are used as the precipitation medium. Methanol is preferred. It is advantageous to acidify the precipitation medium to pH 0 to 5.5 with hydrochloric acid or another suitable acid.

The precipitated polymer can be separated as usual, e.g. by filtration, and dried in vacuo.

In some cases, part of the polycarbonate reaction product is also dissolved or dispersed in the precipitation medium, for example in the acidified methanol. This polycarbonate can be isolated in the usual way by removing the precipitant. For example, the methanol can be distilled off under reduced pressure, for example on a rotary evaporator.

A preferred method results from the above description of the method according to the invention, which essentially comprises the following method steps:

1. Make the catalyst anhydrous

2. Placing the anhydrous catalyst in a polymerization reactor

3. Optional addition of an inert reaction medium

4. Add carbon dioxide

5. Add the epoxy

6. Warm the reactor to the reaction temperature. 7. Optionally add more carbon dioxide

8. After the polymerization reaction has subsided, work up the reactor contents onto the polycarbonate,

Steps 5 and 6 can be interchanged (first heating, then adding epoxy). As already mentioned, the catalyst can be made anhydrous by heating under inert gas in the reactor, as a result of which steps 1 and 2 coincide.

The method according to the invention has the following advantages over the methods of the prior art:

i) The required amounts of catalyst are significantly lower, i.e. more grams of polymer are produced per gram of catalyst. This increases the economics of the process.

ii) The polymerization time is 1 to 10, in particular 2 to 5 hours, typically about 3 to 4 hours, considerably shorter, which greatly improves the economics of the process.

iii) The weight-average molecular weights M _{w of} the polycarbonates obtained are significantly higher at 30,000 to 1,000,000 than according to the prior art. Molding compounds or molded parts, foils, films and fibers with good usage properties, in particular good mechanical properties, can be produced from polycarbonates with these molecular weights.

iv) By choosing suitable reaction conditions, the polymerization reaction can be controlled so that little or no undesirable by-products are formed. In particular, the formation of the interfering polyether homopolymers (III in the reaction scheme given at the outset) and the interfering cyclic carbonates IV is significantly reduced or completely avoided. The reduced or missing by-products III and IV increase the yield of polycarbonate and thus improve the economics of the process. The lack of by-products also saves time-consuming separation from the main product. This significantly improves economy.

v) Furthermore, the mechanical and other properties of the polycarbonates and the molded parts produced therefrom improve due to the low or undetectable content of disruptive by-products.

In particular, with the method according to the invention

Manufacture polycarbonates that contain no or only insignificant amounts of cyclic carbonates and no or only insignificant amounts of polyether.

By choosing suitable reaction conditions,

Process product polycarbonate set the ratio of alternating polycarbonate I to polyether carbonate II. The after In a preferred embodiment, polycarbonates obtainable according to the invention have at least 50, preferably at least 70, in particular 75 to 95%, carbonate linkages in the polymer chain.

A high proportion of carbonate linkages means a low proportion of polyether segments in the polymer chain. Pure alternating polycarbonate I has 100% carbonate linkages. A high proportion of carbonate linkages in the process product therefore means that the process product comes close to the alternating polycarbonate I. If the proportion of carbonate linkages is lower, the process product comes close to polyether carbonate II.

The reaction conditions which control the polymerization reaction with regard to the ratio of main products I and II / by-products III and IV, and in particular with regard to the proportion of carbonate linkages in main product I and II and thus the (mechanical and other) properties, include in particular the catalyst, but also the amount of epoxy and C0 ₂ , the C0 pressure and pressure, and the temperature control of the reaction.

For example, for PO as epoxy zinc carboxylate catalysts, mainly polycarbonates with> 90% carbonate linkages. They have a high modulus of elasticity and low elongation at break and are tough and tough. Such tough solid polycarbonates are suitable e.g. for the production of molded parts.

In contrast, multi-metal cyanide catalysts with PO tend to give polycarbonates with 70 to 90% carbonate linkages. They have a low modulus of elasticity and high elongation at break and are flexible. Such flexible polycarbonates are suitable e.g. for the production of foils and films.

The former tough polycarbonates resemble in terms of modulus of elasticity and elongation at break similar to polyesters such as polybutylene terephthalate (e.g. Ultradur® from BASF), the latter flexible polycarbonates are similar in terms of modulus of elasticity and elongation at break to aromatic-aliphatic copolyesters (e.g. Ecoflex® from BASF) or polyethylenes such as LLDPE (linear low density polyethylene) or LDPE (low density polyethylene).

In particular, the polycarbonates according to the invention, insofar as they were produced using a zinc carboxylate catalyst, have a modulus of elasticity above 500 MPa, determined in a tensile test at 23 ° C. on cylindrical strands of 2.5 mm in diameter 25 mm clamping length, 10 mm measuring length standard travel, 50 mm / min pulling speed and 10 kN pulling force.

In addition, the polycarbonates according to the invention, provided they were produced using a multimetal cyanide catalyst, have an elongation at break of more than 500%, determined in a tensile test at 23 ° C. on cylindrical strands of 2.5 mm in diameter with a clamping length of 25 mm, a measuring length of 10 mm as standard, 50 mm / min pulling speed and 10 kN pulling force.

The details for the production of the cylindrical strands and for the measurement of the modulus of elasticity and the elongation at break are as follows: The polycarbonates are dried at 60 to 80 ° C. for 4 to 12 hours in vacuo. 4 to 5 g of the material are placed in a melt flow capillary rheometer (e.g. type MP-D from Göttfert). After 3 to 4 minutes of preheating, the strands with a load of 2.16 kg at 150 ° C. are extruded through the die of the rheometer (cylindrical die of 2 mm diameter) and allowed to cool in air. Tensile test: the approx. 50 mm long strands with a diameter of 2.5 mm are examined with a tensile force of 10 kN and a tensile speed of 50 mm / min, whereby the clamping length (distance between the clamping jaws) is 25 mm and the measuring length standard path 10 mm. The measurement is carried out according to DIN 53455-3.

These polycarbonates are also the subject of the invention.

The choice of catalyst therefore essentially determines the property profile of the polycarbonates.

The process according to the invention allows the production of polycarbonate molding compositions with tailored properties which can be varied within wide limits, in particular tailored and variable mechanical properties.

The polycarbonates according to the invention, in particular polycarbonates produced with ethylene oxide, are notable for good biodegradability, i.e. they are broken down comparatively quickly by microorganisms in the ground, sunlight, hydrolysis or several of these mechanisms.

The invention accordingly also relates to the polycarbonates obtainable by the process according to the invention, in particular also those with at least 50, in particular at least 70%, carbonate linkages in the polymer chain, and those with good biodegradability. The invention furthermore relates to thermoplastic molding compositions which contain the polycarbonates mentioned. Other constituents of these molding compositions can be polymers, for example polyesters such as polybutylene terephthalate, polyethylene, and biodegradable polymers. Examples of the latter are aromatic-aliphatic copolyesters (eg Ecoflex® from BASF), polymers based on lactic acid (polylactide) or starch (starch polymers), polyanhydrides, polyhydroxybutyrates, polyethylene glycols, polyvinyl alcohols, polyvinyl acetates, cellulose acetates and starch acetates called do.

They are known to the expert and z. B. described in the following writings, which is why further information is unnecessary:

M. Vert et al. , Biodegradable Polymers and Plastics (Second International Scientific Workshop on Biodegradable Polymers and Plastics), Royal Society of Chemistry, Cambridge 1992, Special Publication 109;

Y. Doi et al. , Biodegradable Plastics and Polymers (Proceedings of the Third International Scientific Workshop on Biodegradable Plastics and Polymers, Osaka), Elsevier, Amsterdam 1994, Studies in Polymer Science, 12;

G. J. Griffin, Chemistry and Technology of Biodegradable Polymers, Blackie, London 1994.

The thermoplastic molding compositions may also contain conventional additives and processing aids. Such additives and processing aids are lubricants and mold release agents, colorants such as pigments and dyes, flame retardants, antioxidants, light stabilizers, fibrous and powdery fillers and reinforcing agents and antistatic agents in the amounts customary for these agents.

The molding compositions according to the invention can be produced by mixing processes known per se, for example by melting in an extruder, Banbury mixer. Kneader, roller mill or calender at temperatures from 150 to 300 ° C. However, the components can also be mixed "cold" without melting and the powdery or granular mixture is only melted and homogenized during processing.

Moldings of all kinds, including foils, films, coatings and fabrics as well as fibers, can be produced from the molding compounds. The films can be produced by extrusion, rolling, calendering and other processes known to the person skilled in the art. The molding compositions according to the invention are thereby heated and / or friction alone or with the use of softening or other additives to form a processable film or a sheet (plate). The processing into three-dimensional shaped bodies of all kinds takes place, for example, by injection molding.

The coatings come e.g. Coatings of surfaces made of paper, wood, plastic, metal or glass.

Another object of the present invention is thus the use of the thermoplastic molding compositions according to the invention for the production of moldings, films, films, coatings and fibers. Furthermore, the molded articles obtainable by using the thermoplastic molding compositions are films, films, coatings and fibers.

Examples

1. Feedstocks

The following catalysts were used:

Zn (Glu): zinc glutarate, produced as follows:

35 g of ground zinc oxide in 250 ml of absolute toluene were placed in a 1 1 four-necked flask which was provided with a stirring bone, heating bath and a water circuit. After adding 52 g of glutaric acid, the mixture was heated to 55 ° C. for 2 hours with stirring. The mixture was then heated to boiling, the water of reaction being distilled off azeotropically until no more water passed over. The toluene was distilled off and the residue was dried at 80 ° C. under high vacuum.

DMC: double metal cyanide compound, prepared as follows:

In a stirred tank with a volume of 800 l, equipped with a inclined-blade turbine, dip tube for metering, pH electrode, conductivity measuring cell and scattered light probe, 370 kg of aqueous hexacyanocobaltoic acid H ₃ [Co (CN) ₆ ] (cobalt content 9 g / l ) submitted and heated to 50 ° C with stirring. Subsequently, 209.5 kg of aqueous zinc acetate dihydrate solution (zinc content 2.7% by weight), which was also heated to 50 ° C., were metered in with stirring (stirring power 1 W / 1) within 50 min. Subsequently, the wur- 8 kg Pluronic ^® PE 6200 (this is a EO-PO block copolymer having 20 wt.% EO and an average molecular weight of about 2000 to 5000, available from BASF) and 10.7 kg of water with stirring, added. Then 67.5 kg of aqueous zinc acetate dihydrate solution (zinc content: 2.7% by weight) were metered in with stirring (stirring energy: 1W / 1) at 50 ° C. within 20 min. The suspension was stirred at 55 ° C. until the pH had dropped from 3.7 to 2.7 and remained constant. The precipitate suspension thus obtained was then filtered off by means of a filter press and washed in the filter press with 400 l of water. The moist filter cake obtained was dried in a forced air oven at 60 ° C. to constant weight.

Commercial qualities from BASF were used as monomers without further purification:

C0: carbon dioxide EO: ethylene oxide PO: propylene oxide

The inert reaction medium toluene was dried over sodium.

2. Experimental instructions for polymerization

a) Make the catalyst anhydrous

The catalyst (type and amount see tables) was placed in a reactor. A 300 ml autoclave made of stainless steel, which was equipped with a mechanical stirrer, or a 3.5 1 autoclave with a mechanical stirrer was used for the scale-up experiments (Tables 3A and 3B). After the reactor had been closed, it was flushed with N ₂ gas, heated to 130 ° C. under a stream of N and kept at these conditions for 4 hours. Then allowed to cool to room temperature.

b) polymerization

The inert reaction medium toluene (amount see tables) was pressed into the reactor with CO ₂ gas. It was then pushed into the reactor at room temperature (23 ° C) as long as C0, to the bark in the Ta ^¬ mentioned C0 ₂ -Vordruck was reached. The duration of this contacting of the catalyst with CO ₂ was 1 to 120 min, depending on the CO ₂ pressure and reactor volume. The epoxide (type and amount see tables) was then pressed into the reactor with CO gas and the reactor was then heated to the reaction temperature T _R given in the tables. Subsequently, at the reaction temperature T _R, C0 _{2 was} pressed into the reactor until the final C0 pressure given in the tables was reached. The reactor was kept at the reaction temperature T _R for a certain time (time duration see tables), whereby no C0 _{2 was} replenished. The mixture was then allowed to cool to room temperature.

c) processing

The reactor was vented and the reactor contents were in 1 1 methanol, which was concentrated with 5 ml. Hydrochloric acid (37% by weight) was acidified, poured in. A polymer precipitated out, which was filtered off and dried in vacuo at 60 ° C. overnight. In some examples (identified by the suffix R in the tables), the methanol liquid phase obtained on filtering was also evaporated to dryness on a rotary evaporator. A polymer-containing residue was obtained.

3. Measurements

In order to clarify whether the polymer obtained is a mixture (blend) of alternating polycarbonate (I in the above-mentioned scheme) and polyether homopolymer III or a random polyether carbonate copolymer II, an NMR spectrometer AMX 300 from Fa. Bruker ¹ H and ¹³ C NMR spectra of pure alternating polycarbonate I, of pure polyether homopolymer III and of the polymer obtained were recorded and compared with one another. As a result, the polymer precipitated was a polyether carbonate copolymer and not a blend.

The precipitated polymer, as well as the polymer obtained from the methanol liquid phase in the case of the R examples, were examined for molecular weights, glass transition and melting temperatures, and for the proportion of carbonate linkages, and for by-products (cyclic carbonates and polyethers).

The molecular weights of the polymers given in the tables (weight average M _w and number average M _n ) were determined by means of gel permeation chromatography (GPC). The details were as follows:

Eluent: hexafluoroisopropanol (HFIP)

Flow rate: 0.5 ml / min GPC system: 150 C ALC / GPC from Waters

Detector: ERC 7510 differential refractometer from ERC

Columns: HFiP Gel guard column and HFiP Gel linear separation column, both from Polymer Laboratories

Calibration: with narrowly distributed polymethyl methacrylate standards with molecular weights M from 505 to 2,740,000 from PSS

Temperature: 42 ° C. The glass transition temperatures T _g and melting temperatures T _m given in the tables were determined by means of differential scanning calorimetry (DSC) in accordance with DIN 53765. The details were as follows: heating from room temperature to 180 ° C., cooling to -100 ° C., heating to 180 ° C., rate in each case 20 K / min, determination in the second run.

The data given in the tables for the proportion of carbonate linkages in the polymer and for the presence of by-products (cyclic carbonates and polyethers) were determined on the basis of ^ -H-NMR spectra of the precipitated polymer. To this end, ^X H-NMR spectra of the polymer were recorded on a ^ -H-NMR spectrometer from Bruker and evaluated qualitatively and quantitatively.

4. Results

The following tables summarize the results. The tables labeled A contain the reaction conditions (see test instructions above) and the tables labeled B indicate the results.

It means:

Duration: Duration of the reaction

M _w : weight average molecular weight M _w M _n : number average molecular weight M _n

T _g : glass transition temperature of the polycarbonate

T _m : melting temperature of the polycarbonate

Proportion of CV: Proportion of carbonate linkages in the polymer

By-products: "no" with a content of cyclic carbonates and polyethers of less than or equal to 5% by weight, "yes" with a content of more than 5% by weight, each based on the polymer

-: not determined

V: for comparison

R: Examination of the residue from the methanol liquid phase.

Table 1A: C0 / PO copolymer, variation of C0 ₂ pressure and temperature, conditions

^ Only PO (without C0 ₂ ) was homopolymerized.

²⁾ The catalyst was not made anhydrous by baking out.

³⁾ The catalyst was made anhydrous outside of the reactor by heating and then placed in the reactor. ⁵⁾ Example 10 was repeated to check the reproducibility.

Table IB: CO ₂ / P0 copolymers, variation of CO ₂ pressure and temperature, results

^J) Only PO (without. C0 ₂ ) was homopolymerized. ²⁾ The catalyst was not made anhydrous by baking out.

³⁾ The catalyst was made anhydrous outside of the reactor by heating and then placed in the reactor.

⁴⁾ The polymer-like residue was examined, which remained in the liquid phase in Example 8 after the polymer had precipitated and was isolated by removing the methanol. ⁵⁾ Example 10 was repeated to check the reproducibility.

Example 2V shows that the process according to the invention did not work with a non-anhydrous catalyst. It proves that it is essential to the invention to use the catalyst in anhydrous form.

Examples 3 to 8V illustrate the influence of the variation in the CO _{2 end} pressure. At C0 end pressures of 150 to 50 bar (Examples 3 to 6), polycarbonates with molecular weights M _w over 200,000 were obtained, which contained a maximum of 5% by weight of undesired by-products (sum of cyclic carbonates and polyethers). In contrast, at C0 end pressures of 20 bar (Examples 7V to 8RV) polycarbonates with molecular weights M _w up to approx. 110,000 were obtained which contained more than 5% by weight of by-products.

The example pair 4/5 illustrates the variation in the amount of catalyst.

Examples 9V and 10 illustrate the influence of the variation in the reaction temperature T _R. At temperatures of 50 ° C (example 9V) to give polycarbonates which more than 5 wt .-% unwanted ^'by-products contained. In contrast, showed temperatures of 65 ° C (Example 10) polycarbonates with most 5 wt .-% by-products.

The pair of examples 10 / 10a illustrates the good reproducibility of the method according to the invention: the measured values agree well. This also applies to the scale-up to larger product quantities, see tables 3A and 3B below.

In Examples 11 to 15, zinc glutarate was used as the catalyst, not DMC. Polycarbonates were obtained whose molar masses M _{w were} comparable to the polycarbonates produced by means of DMC. The proportion of carbonate linkages was 88 to 97% higher than that of polycarbonates via DMC.

The final CO pressure was varied from 20 to 100 bar in Examples 11 to 15, which resulted in different molar masses and proportions of carbonate linkages. Table 2A: CO ₂ / PO copolymer, variation of PO amount and amount of catalyst, conditions

⁶⁾ Example 16 is identical to Example 4 from Tables 1A and 1B and was listed again for better comparability.

Table 2B: CO ₂ / PO copolymer, variation of PO amount and amount of catalyst, results

⁶⁾ Example 16 is identical to Example 4 from Tables 1A and IB and was listed here again for better comparability.

Examples 16 to 19 show that a reduction in the amount of catalyst and an increase in the amount of epoxy (PO) gives polycarbonates with high molar masses M _w .

Tables 3A and B below illustrate a scale-up of the process to larger product quantities. An autoclave with 3.5 1 instead of 300 ml volume was used.

Table 3A: C0 ₂ / PO copolymer, scale-up to larger product quantities, conditions

⁷⁾ Example 20 is identical to Example 4 from Tables 1A and IB and was listed again for better comparability.

Table 3B: C0 / PO copolymer, scale-up to larger product quantities, results

⁷⁾ Example 20 is identical to Example 4 from Tables 1A and 1B and was listed again for better comparability.

Examples 20 to 23 show that a scale-up by a factor of 10 (examples 20 and 21), by a factor of 15 (examples 20 and 22) or by a factor of 21 (examples 20 and 23) was possible: 24 ml PO were used in Example 20, 240 ml PO in Example 21, 360 ml PO in Example 22 and 500 ml PO in Example 23. The profile of properties of the polycarbonates obtained was comparable.

The process according to the invention is therefore also flexible with regard to the amounts of substance used or obtained.

In Tables 1 to 3 above, propylene oxide was used as the epoxy. Tables 4A and 4B below summarize the results for ethylene oxide / CO ₂ copolymers.

Table 4A: CO ₂ / EO copolymer, variation of CO ₂ pressure and temperature, conditions

Table 4B: C0 / EO copolymer variation of C0 pressure and temperature, conditions

Examples 24 to 26 show the influence of the variation of final CO pressure and reaction temperature T _R for EO as epoxy. At CO _{2 end} pressures of 100 to 20 bar and temperatures of 50 to 80 ° C., polycarbonates according to the invention with molecular weights M _w of at least 30,000 were obtained.

The mechanical properties were examined for some selected polymers. The results are summarized below.

5. Mechanical properties

The mechanical properties of the polycarbonates from Example 10 (copolymer of CO and PO with DMC catalyst) and from Example 12 (copolymer of CO and PO with Zn (Glu) catalyst) were determined and compared with those of other polymers. These other polymers were ültradur® B 4520, a polybutylene terephthalate PBT (polyester) from BASF and Ecoflex®, an aromatic-aliphatic biodegradable copolyester from BASF.

To this end, strands were produced from the polymers as follows: the polycarbonates were dried at 60 to 80 ° C. for 4 to 12 hours in vacuo. 4 to 5 g of the material were placed in a melt flow capillary rheometer (type MP-D from Gottfert). After 3 to 4 minutes of preheating, the strands were extruded with a load of 2.16 kg at 150 ° C. through the die of the rheometer (cylindrical die of 2 mm diameter) and allowed to cool in air.

The measurement was carried out in a tensile test at 23 ° C, as follows: the approx. 50 mm long strands with a diameter of 2.5 mm were examined with a tensile force of 10 kN, the clamping length (distance between the clamping jaws) 25 mm and the measuring length Standard path was 10 mm. For better comparability, the tensile tests were carried out at two different train speeds, namely 5 mm / min and 50 mm / min, see examples 28a and 28b. The measurement was carried out in accordance with DIN 53455-3.

Table 5 summarizes the results. Table 5: Comparison of the mechanical properties of the polycarbonates

Comparing Examples 27 and 28a, the polycarbonate from Example 10 (here Example 27) produced using DMC showed a significantly lower modulus of elasticity and a much higher elongation at break than the polycarbonate from Example produced using Zn (Glu) 12 (here example 28a). The polycarbonate via DMC catalyst was therefore flexible and the polycarbonate via Zn (Glu) catalyst was tough.

Comparing Examples 28b and VI, the polycarbonate shows a modulus of elasticity via Zn (Glu) catalyst that comes close to the PBT Ultradur®.

If you compare Examples 27 and V2, the polycarbonate via DMC catalyst shows a modulus of elasticity and an elongation at break that come close to that of the Ecoflex® polyester.

The method according to the invention accordingly allows the production of polycarbonates with interesting and tailor-made property profiles.

Claims

claims

1. Process for the production of high molecular weight aliphatic polycarbonates with the following properties

the weight-average molecular weight M _w , determined by means of gel permeation chromatography using hexafluoroisopropanol as eluent and polymethyl methacrylate standards, is 30,000 to 1,000,000,

the content of cyclic carbonates and polyethers taken together is a maximum of 5% by weight,

by polymerizing carbon dioxide with at least one epoxide of the general formula 1

in which the radicals R independently of one another represent hydrogen, halogen, -N0, -CN, -COOR or a hydrocarbon group with 1 to 20 C atoms, which can be substituted,

using at least one catalyst selected from the group consisting of zinc carboxylates and multimetal cyanide compounds,

characterized in that the catalyst is used in anhydrous form and in that the catalyst is first brought into contact with at least a portion of the carbon dioxide before the epoxide is added.

2. The method according to claim 1, characterized in that the catalyst is made anhydrous by heating it before the start of the polymerization in an inert gas stream or in vacuo to the absence of water.

3. Process according to claims 1 to 2, characterized in that the epoxide used is ethylene oxide, propylene oxide, butene oxide, cyclopentene oxide, cyclohexene oxide, i-butene oxide, acrylic oxides or mixtures thereof.

4. Process according to claims 1 to 3, characterized in that zinc glutarate, zinc adipate or mixtures thereof are used as zinc carboxylates.

5. Process according to claims 1 to 4, characterized in that those of the general formula 2 are used as multimetal cyanide compounds,

M ¹ _a [M (CN) _b A _c ] _d • f MlgX _n • h H ₂ 0 • e L • k P (2)

in which mean:

M ¹ at least one metal ion selected from the group comprising Zn ²⁺ , Fe ⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ , Ni ²⁺ , Mn ²⁺ , Sn ²⁺ , Mo ⁴ +, Mo ⁶⁺ , Al ³⁺ , V ⁴⁺ , v ⁵⁺ , sr ²⁺ , W ⁺ , W ⁶ +, Cr ²⁺ , cr ³⁺ , Cd ⁺ , Pd ²⁺ , a ³⁺ ,

Ce ³⁺ , Ce ⁺ , Eu ³⁺ , Mg ²⁺ , Ti ³⁺ , Ti ⁴⁺ , Ag ⁺ , Rh ⁺ , Ru ²⁺ , Ru ³⁺ ,

M ² at least one metal ion selected from the group comprising Fe ²⁺ , Fe ³⁺ , Co ⁺ , Co ³⁺ , Mn ²⁺ , Mn ³⁺ , V ⁺ , V ⁵⁺ , Cr ⁺ , Cr ³⁺ , Rh ^{3 +} , Ru ³⁺ , Ir ³⁺ ,

where M ¹ and M ^{2 can be the} same or different,

A at least one anion selected from the group comprising halide, hydroxide, sulfate, hydrogen sulfate,

Carbonate, hydrogen carbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate, nitrate, nitrosyl, phosphate, dihydrogen phosphate, hydrogen phosphate,

where A and X can be the same or different,

L at least one water-miscible ligand, selected from the group consisting of alcohols, aldehydes, ketones, ethers, polyethers, esters, polyesters, polycarbonates, ureas, amides, nitriles, sulfides, amines, ligands with py- ridin-nitrogen, phosphides, phosphites, phosphines, phosphonates, phosphates,

P at least one organic additive selected from the group comprising polyethers, polyesters, polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycol glycidyl ethers, polyacrylamide, poly (acrylamide-co-acrylic acid), polyacrylic acid, poly (acrylamide-co-maleic acid), polyacrylonitrile, polyalkylacrylates , Polyalkyl methacrylates, polyvinyl methether, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone, poly (N-vinylpyrrolodone-co-acrylic acid), polyvinyl methyl ketone, poly (4-vinylphenol), poly (acrylic acid-co-sty - rol), oxazoline polymers, polyalkyleneimines, maleic acid, maleic anhydride copolymer, hydroxyethyl cellulose, polyacetete, ionic surface-active and surface-active compounds, bile acid and the salts, esters and amides of bile acid, carboxylic acid esters, polyhydric alcohols, glycosides,

where a, b, d, g and n are whole or fractional numbers greater than zero, and

where a, b, c, d, g and n are chosen so that the electro-neutrality of the cyanide compound M ^X [M (CN) A] or the compound M ^ -X is ensured.

6. Process according to claims 1 to 5, characterized in that a compound is used as the multimetal cyanide compound which is obtainable by reacting aqueous hexacyanocobaltoic acid H ₃ [Co (CN) ₆ ] with aqueous zinc acetate solution.

7. The method according to claims 1 to 6, characterized in that it essentially comprises the following process steps:

1. Make the catalyst anhydrous

2. Placing the anhydrous catalyst in a polymerization reactor

3. Optional addition of an inert reaction medium. 4. Addition of carbon dioxide

5. Add the epoxy

6. Warm the reactor to the reaction temperature

7. Optionally add more carbon dioxide

8. After the polymerization reaction has subsided, working up the reactor contents onto the polycarbonate,

5 where steps 5 and 6 can be interchanged.

8. Aliphatic polycarbonates, obtainable by the process according to claims 1 to 7.

10 9. Aliphatic polycarbonates according to claim 8, characterized in that they contain at least 70% carbonate linkages in the polymer chain.

10. Aliphatic polycarbonates according to claims 8 to 9, 15 characterized by good biodegradability.

11. Aliphatic polycarbonates according to claims 8 to 10, which are produced using a zinc carboxylate catalyst, characterized by an elastic modulus above 500 MPa,

20 determined in a tensile test at 23 ° C on cylindrical strands of 2.5 mm diameter with 25 mm clamping length, 10 mm measuring length standard travel, 50 mm / min tensile speed and 10 kN tensile force.

12. Aliphatic polycarbonates according to Claims 8 to 10, which are produced using a multimetal cyanide catalyst, ^■ characterized by an elongation at break greater than 500, determined in a tensile test at 23 ° C. on cylindrical strands of 2.5 mm diameter at 25 mm clamping length, 10 mm measuring length standard travel, 50 mm / min pulling speed and 10 30 kN pulling force.

13. Thermoplastic molding compositions containing aliphatic polycarbonates according to claims 8 to 12.

35 14. Use of the thermoplastic molding compositions according to claim 13 for the production of moldings, foils, films, and fibers Beschichtun ^¬ gen.

15. Moldings, foils, films, coatings and fibers from the 40 thermoplastic molding compositions according to claim 13. ^•

45