DE1420434C - Process for the production of high molecular weight linear polycarbonates - Google Patents

Description

Shaped structures made by known processes, preferably with the addition of a certain amount of a monophenol as a chain terminator and thus as a molecular weight regulator produced high molecular weight linear polycarbonates made from dihydroxydiarylalkanes, sulfones, sulfoxides. -sulphides, -ethers and those of mixtures of these compounds and mixtures with other aromatic or aliphatic compounds Dihydroxy compounds show good mechanical properties, such as high tear strength. Shock resistance, Impact strength, notched impact strength and a high degree of martens (see e.g. the German Patent specification 971 790, Kunststoffe 49 (1959), pp. 3 to 8. and Industrial and Engineering Chemistry. 51 (1959). Pp. 157 to 160).

Certain properties, especially the impact resistance of foils, the notched impact strength and stress corrosion resistance of injection molded objects, are heavily dependent on the manufacturing conditions, with minor changes, such as those at repeated implementation of the manufacturing process can occur unintentionally, to considerable Can lead to scattering of the measured values.

It has now been found that polycarbonates of the type mentioned can be used with very good, in some cases still improved and in particular largely constant mechanical properties thereby obtained can that you in a known manner z. B. by phosgenating alkaline solutions of aromatic Dihydroxy compounds or by transesterification of diaryl carbonates with aromatic dihydroxy compounds. preferably also with the addition of a certain amount of a monophenol as a molecular weight regulator produced polycarbonates of higher molecular weight than desired until achieved of the desired average molecular weight by hydrolyzing. Alcoholizing, phenolyzing or double learning removes.

This degradation can be carried out immediately after the production of the high molecular weight polycarbonates or combine with their further processing. The polycarbonates produced according to the invention In particular, they also have significantly higher elongation and notched impact strength compared to polycarbonates of the same average molecular weight, which were prepared in the usual way.

In general, optimal properties are obtained if the degradation is allowed to proceed so far that the mean molecular weight of the not yet degraded, higher polymer polycarbonates to the average molecular weight of the degraded, lower polymer Polycarbonate behaves roughly like 3: 2.

Since, in the case of linear high polymers, the relative viscosity is generally used as a measure of the average molecular weight is determined, those for polycarbonates made from bisphenol A are mostly expedient in Table I below relative viscosities indicated.

Table 1 at *) Relative viscosity l.iulprodukle Ai ^ iingsproclukle 1.30 1.43 1.40 1.56 1.50 1.70 1.60 1.87 Methylciithlorkl hot 2s ( Measured 111 (I.V '/ niiwr solution in

60 The degradation of the higher average molecular weight polycarbonate by hydrolyzing can be achieved by treating it with e.g. B. sodium hydroxide, expediently with the addition of a catalyst, e.g. B. a tertiary amine, by alcoholizing or Phcnolisiert, z. B. by treatment with an aqueous alcohol, optionally with the addition of a little alkali, or heating the polycarbonate with an amount of a monophenol corresponding to the desired degradation and by double transesterification, e.g. B. by heating the polycarbonate with an amount of diphenyl carbonate corresponding to the desired degradation.

So you can z. B. the reaction mixture obtained by reacting bisphenol A with phosgene in aqueous-alkaline solution with a content of methylene chloride as a solvent has arisen, add a suitable amount of a monophenol and optionally triethylamine as a catalyst. at If the amount of phenol is measured correctly, the desired amount is obtained after a short time Dismantling. On the other hand, you can hochmolekularc polycarbonates in a known manner, for. B. in one Extruder, melt, using a suitable amount of a monophenol or of diphenyl carbonate added. The polycarbonate with the desired one is then obtained on exit from the extruder lower molecular weight.

The experiments below show that by the production of polycarbonates according to the invention, certain but initially higher average molecular weight with the addition of appropriate amounts of monophenol and degrading the molecular weight of these polycarbonates by hydrolyzing them under Addition of further specific amounts of a monophenol to the desired molecular weight of polycarbonate with improved properties compared to those prepared in a known manner Polycarbonates of about the same, lower molecular weight by adding accordingly higher amounts of a monophenol during manufacture.

Production of polycarbonates by known processes

I η a mixture of 4540 parts by weight of bisphenol A, 60 parts by weight (A I) or 58 parts by weight (A 2) or 55 parts by weight of (A 3) ρ-tert-butylphenol, 15 (M) O parts of water, 12,000 parts by weight of methylene chloride and 5150 parts by weight of 45% sodium hydroxide solution become 2365 parts by weight of phosgene in 2 hours initiated at 25 C with stirring. Then 16 parts by weight of triethylamine are added. In about an hour the organic phase of the mixture becomes highly viscous, it is diluted with the kneader Sodium hydroxide solution, dilute hydrochloric acid, then washed free of electrolytes with water. The organic Phase is crushed. After evaporation of the methylene chloride and subsequent drying at 140.degree and 0.1 Torr, a granulate is obtained whose relative viscosity is 1.412 (Al) or 1.420 (A 2) or 1.456 (A3). The granulate is made on the injection molding machine processed into forks which show the properties given in Table 2 (A I to A 3).

B c i s ρ i e I

Production of polycarbonates with approximately the same molecular weight

The procedure described above is followed, but with only 30 parts by weight (B1) or 27 parts by weight (B 2) or 22 parts by weight of (B 3) p-tert-butylphenol. After adding 16 parts by weight of triethylamine Accruing highly viscous organic phase (relative viscosity BI = 1.558 or B 2 = 1.572 or B 3 = 1.569) is in the kneader with the alkaline-aqueous layer and a further 50 parts by weight of triethylamine and 42 parts by weight of p-tert-butylphenol and then, as described above, with diluted Sodium hydroxide solution, dilute hydrochloric acid, then washed free of electrolytes with water and worked up. The dried granulate has a relative viscosity of 1.415 (B 1) or 1.423 (B 2) or 1.452 (B 3). It is, as described above, processed into forks which have the properties given in Table 2 (B I to B 3) show.

Table 2

Polycarbonal

A 1
A2
A3

B 1
B2
B 3

Relative
Initial viscosity
after Tear resistance
kg'cnr strain Bend
strength Bending angle Notched bar
/ ability product Run away 664 Cl kg cnr cmkgcm ' _ 680 9 77 10.6 - 688 8th 55 7.6 '- 656 11th 79 . 7.8 1.415 661 66 * 87 62.6 1,423 655 62 85 62.8 1.452 65 86 58.7 , 412 226 , 420 214 , 456 245 , 558 154 , 572 155 , 569 136

Marlens / ahl
C.

120

105
104

126
124
126

Claims (2)

Patent claims: 1. Process for the production of high molecular weight linear polycarbonates, thereby characterized that one in well-known Manned polycarbonates of higher average molecular weight than desired up to Achieving the desired average molecular weight by hydrolyzing, alcoholizing, Phenolysis or double transesterification degrades. 2. The method according to claim 1, characterized in that that the degradation immediately after the production of the high molecular weight polycarbonates carries out or connects with their further processing.