DE2266022C2 - - Google Patents

Description

The invention relates to the use of polyketones, especially of polyketones that can be processed as a melt are used for the production of molded parts and insulation of electrical conductors.

As part of the constant search for polymers that at elevated temperatures, for example as insulation can be used for electrical wires and cables, many polymers with a wide variety of recurring Units and various bonds, e.g. B. aromatic units through bonds such as Imide bonds, ether bonds, sulfone bonds and ketone bonds are proposed. Unfortunately with the increase in potential performance at increased Temperatures the suitability of the polymers for processing less in the melt. In the majority of the  Cases occur the same deterioration in workability in the melt when trying to heat-resistant Polymers with an elongation of at least about 50%, a necessary property if with the polymer insulated electrical wires and cables around themselves should be rotated without breaking the insulation, to manufacture.

Aromatic polyketones are known to have good resistance against thermal degradation. The U.S. patent 30 65 205 describes the polymerization of certain reactants with Friedel-Crafts catalysts to polyketones, taking as typical Friedel-Crafts catalysts Iron (III) chloride and boron trifluoride are mentioned. The proposed reactants fall into two classes, the first of which is made of aryl ethers and multinuclear aromatic compounds, one compound this class with a connection from a second Class made from aliphatic and aromatic diacyl chlorides exists, is heated. The basic reactions can be summarized as follows:

and

where HBH is a polynuclear aromatic hydrocarbon, e.g. B. naphthalene, HR-O-RH an ether, for. B. diphenyl ether, and Cl-A-Cl a diacyl chloride, e.g. B. terephthaloyl chloride or is phosgene. When phosgene and diphenyl ether are implemented are, the polymer formed contains the recurring unit

Another way is in the British patent 10 78 234. Here are "polyarylene polyethers" by reacting an alkali double salt of a divalent Phenols made with a dihalobenzene compound. The dihydric phenol can contain a keto group. So it is stated that 4,4'-dihydroxybenzophenone leads to a polyketone.

The same recurring unit results according to British Patent 9 71 227 by implementation of diphenyl ether with phosgene, through polycondensation of diphenyl ether-4-carbonyl chloride and by reaction of diphenyl ether with diphenyl ether-4,4'-dicarbonyl chloride.

A number of patents that have improved methods for Manufacture related to polyketones have been granted since then been. For example, in the processes the subject of U.S. Patents 34 41 538 and 34 42 857 are hydrogen fluoride boron trifluoride catalysts used so a system that was used earlier in "Boron Fluoride and its Compounds as Catalysts "by Topchiev and co-workers, Pergamon Press (1959), page 122, J. Org. Chem. 26, 2401 (1961) and I. & E. Chem. 43, 746 (1951) has been. An improved method is also described in British Patent 10 86 021.

Example 10 of British Patent 9 71 227 describes a process for the preparation of a polymer from recurring units of the formula

It is found that the product is not up to 350 ° C  Showed signs of flowing and producing Fibers obviously had to be spun from solutions. The product is further described in Example 1 of the US patent 34 41 538, where it is described as a polymer with low Stretch that gives tough, opaque brown films is referred to as it is in the British patent specification 11 53 527 as highly crystalline and ineffective, d. H. marked as unsuitable for processing in the melt becomes.

It follows from this that this polymer suitable for use at high temperatures, but because of its inability to process is unsuitable in the melt. There is therefore a Need for melt processable polyketones, those from recurring units of the formula

consist.

The invention relates to the use of polymers with recurring units of the formula

those with chain terminators, which compared to benzene with Acetyl chloride and aluminum chloride acetylated over 150 times faster are measured and an inherent viscosity of about 0.8 to 1.65 concentrated in a solution of 0.1 g of the polymer in 100 ml H₂SO₄ at 25 ° C and an elongation at break of at least have about 50% at room temperature for the production of moldings  and insulation of electrical conductors.

The polymers themselves and the process for their Manufacture is not the subject of this invention.

The inherent values given in this description Viscosity was determined using the Sorenson method and co-workers, "Preparative Methods of Polymer Chemistry", Interscience (1968), page 44, determined (0.1 g Polymer in 100 ml solution of concentrated H₂SO₄ at 25 ° C).

The one with a stretching speed of 200% per minute The elongation at break measured at 25 ° C is here simply as Denoted "stretch".

Preferred polymers contain as chain terminators Biphenyl, 4-acetoxydiphenyl ether, diphenyl ether, naphthalene or 4-methyldiphenyl ether.

The polymers used according to the invention are characterized by Polymerization of the corresponding monomers by Friedel Crafts catalysis in the presence of an aromatic chain terminator, its rate of acetylation is greater than about 150 in relation to benzene. Polymerization with boron trifluoride is preferred catalyzed. In a preferred embodiment the resistance of the polymer to the Attack increased by certain solvents by practically all polymer chains with an inherent viscosity  less than about 0.6 are extracted therefrom.

The polymers used according to the invention have good ones High temperature properties and can be processed as a melt, making an extrudable product which is suitable for wire and cable insulation. Furthermore they can be molded into parts using conventional injection molding processes are processed.

The inherent viscosity of those used in the present invention Polymers must range from about 0.80 to 1.65 being held. The elongation can be below about 0.80 due to slight fluctuations in the manufacturing process become lower, while a polymer with a inherent viscosity greater than about 1.65 a so high melt viscosity has that at best a rough Extrudate and not necessary for wire insulation smooth, coherent coating is formed. Advantageous the inherent viscosity within the Range from 1.20 to 1.40, preferably around 1.30 held. When encapsulating thin wires with a Polymer whose intrinsic viscosity is above about 1.4, takes place at a speed of 91 to 122 m / minute occasional cracking of the melt instead. Polymers with higher viscosity, however, are suitable for extrusion coating thicker wires or for extruding rods for the granulation or production of fibers.

The inherent viscosity can be selected by aromatic Chain termination agents can be set. It is believed, that the chain terminator through the polymerization one catalyzed with a Friedel-Crafts catalyst Acetylation reaction with the active polymer chain ended. For example, the one catalyzed with boron trifluoride runs Polymerization of monomers the polybenzophenone ether  form, obviously about forming a very reactive intermediate containing carboxonium ions, if the monomer is, for example, an acyl fluoride, a tetrafluoroborate is:

The termination of the chain by the chain terminating agent and then find the removal of the boron trifluoride for example as follows:

The chain terminator should be one for acetylation Responsiveness at least in the same order of magnitude like that have monomers. For the production of polymers that can be processed in the melt (which, so is assumed by adjusting the molecular weight should be the chain terminator for the Acetylation a reactivity (based on benzene) of more than about 150. For example, in the literature (Kimoto, J. Pharm. Soc. Japan, 75, 727 [1955],  and Brown et al., J. AM. Chem. Soc., 81, 5929 [1959]), the following Relative acetylation rate values called CH₃COCl / AlCl₃ in the system:

Table I

The aromatic chain terminator used is preferred non-aliphatic and especially for example through nitro groups, methyl residues, hydroxyl groups, Methoxy radicals, methoxycarbonyl radicals or acetyl radicals, however not on the ring, substituted if very good high temperature properties of the polymer are desired. It is obvious that in such a case means which are subject to oxidative or thermal degradation, are to be avoided as they lead to a discolored polymer to lead. In general, all condensed polynuclear aromatic compounds or aryloxy or aryl substituted Benzenes with sufficient reactivity for acylation and solubility in the reaction medium be used.

Within the for workability in the melt required range of inherent viscosity is log (inherent Viscosity) in a linear relationship to log (mol% Chain terminator). For example, in the polymerization of p-phenoxybenzoyl chloride in the HF / BF₃ system, in which the monomer concentration was 1 mol / liter for  6 hours at 0 ° C and then for 15 hours at 20 ° C at a BF₃ pressure of 0.35 kg / cm² the following Relationship found:

Table II

If a diacyl fluoride monomer, e.g. B. Diphenyl ether (4,4'-dicarbonyl fluoride), used with diphenyl ether, the latter being used in excess the reactive intermediates before and during the polymerization is obviously characterized as follows will:

and

In this case, the final polymer is double end-blocked, d. H. it contains a chain terminator or the rest at each end. In the given example, of course, serves the excess of diphenyl ether as chain terminator, although instead a separate suitable one is equally good Means, e.g. B. biphenyl could be used.

In practice, the end-blocks used according to the invention can then be used Polymers are represented as follows:

Here R 'is the chain terminator and R is a hydrogen atom. If the polymer of a monomeric dicarboxylic acid fluoride and a suitable aromatic hydrocarbon, e.g. B. diphenyl ether, the end-blocked polymers used according to the invention can be represented as follows:

Here R 'is the chain terminator.

If the dicarboxylic acid fluoride in a molar excess over the aromatic hydrocarbon is used, the End-blocked polymers used according to the invention can be represented as follows:

Here R and R ′ are the chain terminators. Naturally R and R 'can be chosen independently of each other, d. H.  Mixtures of chain terminators can be used.

For the preparation of polymers that have an inherent Viscosity in the required range and still a The polymerization must have an elongation of at least about 50% be carried out so that contamination of the polymer by transition metals, e.g. B. Fe, Cr, Co and Ni must be prevented because it is assumed these metals to premature crosslinking and in in any case lead to polymerization, although it has an inherent viscosity in the required range, but a very small one Have stretch. For example, according to Example 1, the US Patent 34 41 538 p-phenoxybenzoyl chloride in the system HF / BF₃ in a reaction vessel made of stainless steel polymerized. Here, a polymer with an inherent Obtained viscosity of 1.18. A film of this polymer has an elongation of only 7.2% and is for wire insulation completely unsuitable.

Accordingly, the reaction must take place in an environment that is of transition metals is essentially free, e.g. B. in vessels Plastics (e.g. polytetrafluoroethylene [PTFE], polyethylene, Polychlorotrifluoroethylene [PCTFE]), in plastic-lined Vessels, aluminum vessels or other vessels be performed. Completely non- metallic vessels for polymerization.

From the mechanism outlined above and from the recurring unit

itself results in different monomers and monomer combinations can be used e.g. B. phenoxybenzoyl fluoride alone or diphenyl ether (4,4′-dicarbonyl fluoride)  with an excess of diphenyl ether. Preferred as a monomer is p-phenoxybenzoyl fluoride, which in most cases is caused by Treatment of a corresponding halide other than fluorine (preferably p-phenoxybenzoyl chloride) with hydrogen fluoride becomes. This can be followed immediately by the introduction of boron trifluoride and the onset of polymerization consequences. It is also possible for the acyl fluoride formed by distillation or the like. From the hydrogen fluoride for separate the subsequent polymerization. In the latter In this case there are color bodies caused by the reaction of hydrogen fluoride with the generally commercially available acyl chloride existing contaminants are formed.

Instead of the acyl halides, p-phenoxybenzoic acid or their C₁-C₃ alkyl esters are used as monomers. The Acid itself can be caused, for example, by Ullmann condensation of phenol and p-chlorotoluene and then with cobalt acetate catalyzed oxidation to produce acid. The Esters can, for example, by alcoholysis of the acid chloride or by esterification of the acid.

Hydrogen fluoride is generally used as a solvent for the polymer formed used and can also on the Participate in the polymerization reaction. For example, closes the mechanism by which the acid chloride polymerizes the conversion of the monomer to an acid fluoride as an intermediate. Boron trifluoride can be a hydrogen fluoride solution, which is about 3 to 30%, preferably about Contains 15 to 25 wt .-% of the monomer to trigger the Polymerization can be added. As an alternative to use of hydrogen fluoride alone can BF₃ a solution of Monomers in hydrogen fluoride and liquid sulfur dioxide be added. This is discussed in more detail below.

When the polymerization is carried out in hydrogen fluoride alone  the polymerization temperature is preferably between about 0 ° and 50 ° C, in particular between about 0 ° C and Room temperature. Polymerization temperatures of around 100 ° C and above should be avoided while being below temperatures 0 ° C the polymerization rate is reduced. The preferred Way is, however, in the polymerization To carry out, for example, 50% by volume of liquid SO₂, keeping the temperature at about 0 ° C, around the SO₂ at the pressure prevailing in the reaction vessel to keep the liquid state. The SO₂ seems to be the ketone components to deprotonate the polymer so that BF₃ is not in ionic association with it, but more loosely in a donor Acceptor complex is held. It is also assumed that the SO₂ affects the extent to which water and alcohol which are formed as by-products of acid or ester polymerization will bind the BF₃. Since the heating during the preferred work-up by spray drying (as below the release of bound is also described BF₃ causes, the beneficial effect of SO₂ in in this regard has not yet been determined quantitatively been. However, the use of SO₂ turned out to be a lot other than advantageous. If the polymer through Precipitation in a non-solvent, e.g. B. acetone, methyl ethyl ketone, Dimethylformamide, dimethylacetamide, N-methylpyrrolidone, acetic acid or chlorinated acetic acid, is isolated, that switches liquid SO₂ one by the heat of dilution of the hydrogen fluoride excessive temperature rise in the solvent largely from. Through the work-up, however Polymer subjected to the action of nucleophilic solvents, the with the polymer with the introduction of thermal Instability can interact.

The resistance of the polymers to attack by ketonic and similar solvents are increased, if the polymer with a solvent, preferably an aliphatic ketone, e.g. B. acetone is extracted.  

The extraction is preferably at temperatures in the range from about 30 to 50 ° C during such a time, that about 4 to 10 wt .-% of the polymer are extracted. The polymer obtained has an inherent viscosity in that required for workability in the melt Area, however, is essentially free of having chains inherent viscosity less than about 0.6 and more stable against solvents under stress. The extraction should if necessary, be carried out before the polymer a temperature above its freezing temperature (about 160 ° C for the homopolymer of benzophenoether) is that by the onset of crystallization the extractability that leads to stress cracking in solvents Lower molecular weight components reduced becomes.

It should be noted that acetone is considered a "non-solvent" among the proportionate mild conditions of workup by precipitation marked and yet for the extraction of the shares with lower molecular weight during longer exposure times, associated with the extraction can be. In fact, acetone can also be used as a "non-solvent" for the precipitation of the crude polymer influence the inherent viscosity to a measurable extent. For example showed a 20% solution diluted with SO₂ to 5% of polybenzophenone ether in hydrogen fluoride the following Relationship of acetone concentration to inherent viscosity, if the solution with stirring in a SO₂-acetone mixture was cast:

Table III

The extracted polymer shows under conditions, under who experience stress cracking in solvents, a significantly increased breaking strength and elongation.

A satisfactory product is obtained by extracting the polymer from the wet workup, but it would be advantageous to avoid this step. For this reason, the polymerization product is preferably subjected to spray drying and not to wet working up by precipitation with a non-solvent. The polymer can be dried in hydrogen fluoride alone, using vessels whose walls are protected against corrosion by suitable lining. However, it has been shown that by using liquid SO₂ a polymer is obtained which has a lighter color than the polymer obtained by spray drying from HF alone. When used instead of hydrogen fluoride for the dilution to the more suitable solids content for spray drying, SO₂ reduces the corrosion of the walls of the spray dryer and, because of its relatively lower cost, enables substantial savings. A detailed description of spray drying using SO₂ can be found in DE-OS 22 06 837.7-09 (corresponding to US Pat. No. 3,751,398) by the applicant, but the preferred embodiment of this process is briefly described:
The polymer solution is diluted to a solids content of about 1 to 2%, a solution being obtained which contains a larger proportion of preferably 90 to 99% by volume SO₂. The diluted solution is conveyed under a pressure of, for example, 1.4 atm at -6 ° C. to a nozzle for two media, from which it is sprayed and at the same time brought into contact with hot air or gaseous SO₂. At inlet temperatures of the gas of 190 to 220 ° C, a finely divided polymer is obtained which contains only about 2 to 5 wt .-% volatile fluorine. The fluorine content of the spray-dried product is then preferably reduced to less than 100 parts per million parts in a vacuum oven, which is kept at 140 ° C., for example.

With the processable in the melt used according to the invention Polymers are easily electrical Conductors, especially wires, in layer thicknesses of about Inject 0.13 to 0.3 mm. The overmolded wire is preferably annealed, for example by heating for two minutes at about 220 ° C, forming a generally abrasion-resistant, strong and dimensionally insulating coating becomes. After annealing, the preferred polymer has an elongation of the order of 125%.

The polymer used according to the invention can according to the Manufacture thermally cross-linked to ensure solvent resistance and dimensional accuracy above the melting point to increase. If, for example, one with polybenzophenone ether overmolded wire about 0.25 to 2 seconds of exposure is exposed to an inert atmosphere at about 1200 ° C the product obtained crosslinked at least superficially, and it shows good resistance to stress corrosion cracking in solvents even before extraction with acetone or other extraction agents. In general, the polymer crosslinked at temperatures in the range of about 300 to 600 ° C will. Of course, both the tempering as well the thermal networking, in turn, depends on time and temperature. Suitable times and temperatures for both treatments can be easily by the expert from the above Specify designs and depend on the intended operating conditions and similar considerations.  

The following examples illustrate the preparation of the Polymers used according to the invention. In these examples all parts and percentages refer to the Weight unless otherwise stated.

Example 1

In a 6 liter bottle made of polytetrafluoroethylene, which comes with a gas inlet made of polytetrafluoroethylene, magnetic stirrer and one made of polytetrafluoroethylene with a dry ice Acetone bath cooled cooling coil was provided 1182 g (5.096 mol) of p-phenoxybenzoyl chloride and 4.132 g (0.027 Mol, 0.525 mol%) of biphenyl. By condensation at -78 ° C were 4 liters of anhydrous hydrogen fluoride in the Reactor introduced. The reaction mixture was removed of hydrogen chloride carefully warmed to room temperature and then cooled to -78 ° C, followed by 532 g (7.85 mol) of boron trifluoride were added slowly under light pressure. After that Addition became the reaction mixture by warming to room temperature left and 20 hours under a positive pressure of Boron trifluoride kept.

The polymer solution was treated with anhydrous hydrogen fluoride diluted and poured into quick-stirring acetone, the polymer was precipitated. The polymer was washed with acetone and water and then at 150 to 160 ° C dried under reduced pressure, 900 g (90%) of one colorless polymers were obtained which had an inherent viscosity of 1.45 and an elongation above 125%.

Example 2 a) Preparation of p-phenoxybenzoyl fluoride

23.25 g (0.10 mol) of p-phenoxybenzoyl chloride were placed in a 50 ml reaction tube made of PCTFE and a magnetic stir bar was inserted. The tube was connected to a PCTFE vacuum line. 10 ml of anhydrous HF were introduced into the reaction tube at −96 ° C. by condensation. The tube was heated to 0 ° C and held at this temperature for two hours. Excess hydrogen fluoride was then removed together with hydrogen chloride by distillation. The residue obtained was dissolved in 20 ml of methylene chloride, to which 1 g of sodium fluoride was added as a means of binding residual hydrogen fluoride. The solution was stirred overnight, then filtered and evaporated to dryness to give a light yellow crystalline mass. Distillation at 100 to 110 ° C (bath) / 0.1 mm Hg gave 20.00 g (0.0926 mol, 93%) of a colorless liquid which solidified at room temperature. Melting point 39 to 40 ° C. Analysis by gas chromatography showed that only one component was present. The same methyl ester as that obtained from p-phenoxybenzoyl chloride was obtained by methanolysis. The infrared spectrum (KBr) showed a strong band at 1803 cm ^-1, which is characteristic of acyl fluorides.

b) Polymerization of p-phenoxybenzoyl fluoride

In a 50 ml tube made of PCTFE, 5.50 g (25.55 mmol) of p- Phenoxybenzoyl fluoride, 0.0118 g (0.0694 mmol, 0.271 mol%) Diphenyl ether given and a stir bar inserted. The pipe was connected to a vacuum line made of PCTFE and with Nitrogen purged. By condensation at -196 ° C were then 20 ml of anhydrous hydrogen fluoride and then 2.60 g (38.29 mmol) Boron trifluoride introduced into the reaction tube. After warming up the reaction mixture was at room temperature for one hour touched. Then excess boron trifluoride with nitrogen driven out of the reaction system. The orange-yellow Viscous polymer solution was made with anhydrous hydrogen fluoride diluted and poured into quick-stirring acetone, the polymer was precipitated. The polymer was washed with acetone and water and then under reduced pressure  Pressure dried at 200 ° C, 4.80 g (95%) of a colorless granular powder with an inherent viscosity of 1.56 and elongation over 125% was obtained.

Example 3

A sample a of 1 kg polybenzophenone ether with an intrinsic viscosity of 1.43 was made with a 19 mm Brabender extrusion press extruded at 410 to 420 ° C. The polymer tape obtained was granulated and placed in a Brabender extruder introduced with a conventional nozzle for extrusion coating Cables was provided. A preheated nickel-plated copper wire 20 AWG was passed through the nozzle and that molten polymer applied to the wire, one adherent, closed wire insulation was obtained. This insulation showed 125% elongation and tensile strength of 1335 kg / cm². The insulated wire was different exposed to elevated temperatures in the air. The time when the elongation had dropped to 50% was determined. The results are mentioned below.

At 250 ° C the insulation has a tensile strength of 600 kg / cm² and an elongation of 150%. This example illustrates the processability as a melt, the high elongation and the good high temperature properties (e.g. resistance to oxidation) the polymers used according to the invention.

Example 4

One made in a reactor from polytetrafluoroethylene Sample of polybenzophenone ether with an inherent viscosity of 1.55 gave a colorless plate by pressing, which when examined no metal contamination by X-ray fluorescence spectroscopy shows. This material showed cracking, when exposed to acetone exposure has been. By extracting this polymer in one Soxhlet extractor with acetone for 15 hours Get a flaky, white extract (4%) that has an intrinsic viscosity of 0.69, while the extracted polymer now had an inherent viscosity of 1.62. One out the extracted polymer pressed plate showed in Acetone no stress cracking. Test rods for tensile tests were stretched in an Instron testing machine, and at When the yield point was reached, acetone was sprayed onto the bars. The influence of this treatment on the tensile strength and elongation is given in the following table.

Claims (1)

Use of polymers with recurring units of the formula which are end-blocked with chain terminators which are acetylated more than 150 times faster than benzene with acetyl chloride and aluminum chloride and have an inherent viscosity of approximately 0.8 to 1.65, measured on a solution of 0.1 g of the polymer in 100 ml H₂SO₄ at 25 ° C and an elongation at break of at least 50% at room temperature, for the production of molded parts and insulation of electrical conductors.