DE2408068B2 - PROCESS FOR THE PRODUCTION OF HALOGEN SUBSTITUTED AROMATIC POLYCARBONATES - Google Patents

Description

in which R is a chlorine or bromine atom, X is an alkylene or alkylidene radical with ί to 6 carbon atoms, a cycloalkylene or cycloalkylidene radical with 5 to 15 carbon atoms, a single bond. -O-. —S—. -SO-. - SO ₂ --CO - or

CH, > CH ₃ -C- CH ₃ CH ₃

means by reacting the aromatic dihydroxy compounds with phosgene by the process the interfacial condensation, optionally in the presence of chain terminators, characterized in that in a first stage the reaction of the aqueous-alkaline Bisphenolate solution with phosgene at pH values between 7 and 9 in the presence of about 2-20 mol%, based on the aromatic dihydroxy compound (s) used, of tertiary amines, to an oligocarbonate with an end group ratio of chlorocarbonic acid ester OH> 1.1 carried out and in a second stage the polycondensation at pH values > 13 and OH concentrations (based on the aqueous phase) between 0.20 and 0.40% by weight, if necessary after a further addition of 2-20 mol% of tertiary amines is carried out.

2. The method according to claim 1, characterized in that triethylamine is used as the catalyst will.

3. Use of the polycarbonates according to claim 1 and 2 for the flame retardancy of halogen-free aromatic polycarbonates.

The homo- or copolycarbonates are obtained by the phase boundary condensation process by a two-stage amine-catalyzed reaction of the corresponding bisphenols with phosgene,
The production of high molecular weight aromatic polycarbonates from bisphenols such as 2,2-bis- (4-hydroxypheny]) propane (bisphenol A) and phosgene in a phase boundary reaction has been known for a long time. This is how it is done. that phosgene in a well-stirred two-phase mixture of aqueous alkaline bisphenolate solution and a polycarbonate solvent. such as tetrachloroethane or methylene chloride, initiates.
To accelerate the reaction and to obtain high molecular weight products, the addition of catalysts such as quaternary ammonium and arsonium compounds or tertiary amines (cf. DT-PS 1046311) is recommended before or after the phosgenation. The catalyst concentration is

tration up to 1% by weight, based on the bisphenol used.

This process is only possible if the condensation of the phosgene with the bisphenol is evident takes place faster than the saponification of the phosgene.

This process is successful on bisphenols, which have the same reactivity as bisphenol A apply.

It is customary and advantageous to use the catalyst to be added after the phosgenation. If the catalyst is present at the beginning of the phosgenation, then a large part of the phosgene saponified, and the achievable mean molecular weights of the polycarbonates obtained are low or the bisphenol conversion is not quantitative.

The known procedures do not lead to success when it applies ο.ο, ο ', ο'-Tetrahalogenbisphenolc of the general formula I to condense with phosgene. The reactivity of these bisphenols will be both due to the steric hindrance of the OH functions,

so as a result of the double ortho substitution in each case as also impaired by the low basicity and nucleophilicity of these bisphenols.

pK values, measured in methanol / water 1: 1, make this clear:

The present invention relates to a process for the production of polycarbonates from aromatic dihydroxy compounds. of which 50-100 mol% bisphenols of the general formula 1 pK,

PK ₂

(D

HO I I OH

R R

Here, R means chlorine. Brom.X Alk vlen. Alkvlids

Bisphenol A. 10.2 11.2 ho tetrabromobisphenol A 7.6 8.5 Tetrachlorobisphenol A 7.0 8.4

In the phosgenation of the inert bisphenols of the formula I, for example, the conventional method is used Process using 1.2-1.5 moles of phosgene / mole of bisphenol, as one would think of economical Reasons, no high molecular weight Polvcarbonate. The result of this reaction

Polycarbonate is of low molecular weight and still contains some chlorocarbonic acid ester end groups. The bisphenol conversion is not complete since larger proportions of phosgene are saponified. With the usual amount of triethylamine of about 1% by weight, as recommended for the polycondensation reaction of bisphenol A polycarbonate, no high molecular weight polycarbonates free _{of chlorocarbonate are obtained from such prephosgenates even in longer reaction times of ι_Γ2 hours.}

The use of higher catalyst concentrations of> 2% by weight is also not promising, since under these conditions a decrease in molecular weight is observed and thus none high molecular weight products arise.

If you still want to produce high molecular weight polycarbonate from ο.ο.ο ', ο'-TetrahaJogenbisphenoIen, so one was previously forced to condense in a homogeneous phase, as is the case for tetrabromobisphenol A in the US-PS 33 34 154 is described.

In US Pat. No. 3,334,154, column 5, lines 36-43 is although they contain the information in general that copol) carbonates are based on halogenated bisphenols and other bisphenols are to be produced by the interfacial process. This general Note, however, is not substantiated by information, which enable a synthesis of copolycarbonates by the phase interface process, which practically free from saponifiable chlorine, d. H. of chlorocarbonic acid ester end groups. So goes the teaching of US-PS 33 34 154 relating to the CopoK carbonate production process not beyond the task familiar to the expert, how it is also set out in the present invention. In addition, according to US-PS 33 34 154 (Column 3. Lines 11-21) generally available copolycarbonates from tetrabromobisphenol-A and other bisphenols not free from saponifiable chlorine, d. H. their content of saponifiable chlorine due to the chlorocarbonic acid ester end groups they contain generally reads between 50 ppm and 100 ppm. This results in a difference in the thermal Stability of the copolycarbonates.

It has now surprisingly been found that polycarbonates can be obtained from aromatic dihydroxy compounds. of which> 50 mol% are Tetrahalogenbisphcno! e of the general formula 1, by interfacial reaction the corresponding starting components can be prepared if the following reaction conditions are used in a continuous two-stage process complies with:

1. Phosgenation of the corresponding bisphenols in the presence of 2 20 mol%, based on used dihydroxy compound (s). of tertiary amines, at a pH between and 9. to achieve precondensates with an end group ratio of chlorocarbonic acid ester to OH> 1.1;

2. Polycondensation of the pre-phosgenals at pH greater than 13 and possibly a higher catalyst concentration according to the claims to one Polycarbonate free from chlorocarbonic acid ester end groups. At this stage the pH is increased by adding an aqueous alkali metal hydroxide solution pH> 13 raised. The OH concentration. based on the aqueous phase, then lies / wipe Π ι and 0.4% by weight.

The reaction time in the first stage is about 5-10 minutes, but can also be shorter during the reaction time in the second stage is 10-60 minutes.

The molar ratio of phosgene to bisphenol should be 1.1-1.5, preferably 1.2-1.3.

The polycarbonates obtained have average molecular weights between 5,000 and 50,000.

If the phosgenation is carried out according to the method according to the invention, but without the addition of catalysts, 1.3-1.5 moles are sufficient Phosgene per mole of bisphenol in the first stage is not sufficient to produce a pre-phosgenate with the desired End group ratio of chlorocarbonic acid ester to OH> 1 to be obtained, as the main amount of phosgene is saponified.

However, phosgertation is carried out under otherwise identical conditions in the presence of the high catalyst concentration according to the claims, it is surprisingly the reaction of the tetrahalobisphenols with phosgene accelerates more than saponification of phosgene.

This finding is surprising insofar as the condensation of sterically unhindered bisphenols ; .5 is known. that a point in time of the addition of the catalyst has a bad influence on the Pohkondensationsreaktion before phosgenation.

In the case of PoK carbonates made from bisphenols of the general formula I, an extremely high catalyst concentration surprisingly does not cause any degradation of the polycondensate if the reaction mixture is stirred for a longer period of time, e.g. B. Polycarbonate made from bisphenol \ passes through a maximum molecular weight under similar conditions. A particular embodiment of the process according to the invention is the production of copolycarbonates based on> 50 mol% of bisphenols of the general formula I and the corresponding chlorine-free and bromine-free bisphenols.

Surprisingly, the reaction conditions mentioned for the process according to the invention are obtained in the first stage of the reaction practically only reaction products of phosgene with the Bisphenols of the general formula I, while the more basic sterically unblocked bisphenols remain in the form of bisphenolates in the aqueous alkaline solution, and only when in stage 2 at pH> 13 and at OH concentration (based on the aqueous phase) between 0.2 and 0.4% by weight of the polycondensation reaction taking place quantitath be condensed, the obtained copolycarbonates molecular weights between 5000 and 50,000 can have.

Suitable bisphenols according to the general formula I. are in particular

2.2-bis- (4-hydroxy-3.5-dichlorophenyl (propane (tetrachlorobisphenol A).

2.2-bis (4-hydroxy-3.5-dibromophenyl) propane (Tetrabromobisphenol Al.

1,4-bis- (4-hydroxy-3,5-dibroinphenylisopropylidene! -Benzene.

1,4-bis- (4-hydroxy-3.5-dk chlorophenyliso-

propylidene! -benzene,
(15 bis (4-hydroxy-3,5-dichlorophenyl! Methane.

Bis (4-hydroxy-3,5-dichlorophenyl) sulfone.

Bis (4-hydroxy-3,5-dichlorophenyl) sulfide.

Bis (4-hydroxy-3.5-dichlorophenyl) ether.

'4

1,1-bis- ('1-hydroxy-3,5-dichlorophenyl) -cyclohexane

(Tetrachlorobisphenol Z),

1,2-bis- (4-hydroxy-3,5-dichlorophenyI) -1.1 -dimethylethane,
Bis (4-hydroxy-3,5-dibromophenyl) methane.

Bis- (4-hydroxy-3,5-dibromophenyl) -sulfone, bis- (4-hydroxy-3,5-dibromophenyl) -sulfiJ, B? S- (4-hydroxy-3,5-riibromopher.yl) - ether, l, l-bis (4-hydroxy-3,5-dibromophenyl) -cyclohexane,
1,2-bis (4-hydroxy-3,5-dibromophenyl) -1, 1-dimethylethane.

As a second starting compound for the production of copolycarbonates, all polycarbonate are suitable known aromatic dihydroxy compounds such as resorcinol, hydroquinone, dihydroxydiarylalkanes. preferably bisphenol A, tetramethylbrsphenol A, bisphenol Z, dihydroxydiaryl ethers, ketones, sulfides, sulfoxides, sulfones and the corresponding alkyl-substituted compounds.

As chain terminators, monophenols are suitable such. B. phenol, p-tert-butylphenol. 2.4.6-tribromophenol and pentabromophenol.

As usual, the solvents used are those which are not miscible with water and are known for polycarbonate aliphatic and aromatic chlorinated hydrocarbons such as methylene chloride. Chloroform. 1,2-dichloroethane and chlorobenzene and mixtures of these solvents.

The reaction temperature can be freely selected within wide limits. The reaction is advantageously carried out at temperatures below the boiling point of the solvent.

Suitable catalysts are those for polycarbonate production after the two-phase boundary process known tertiary amines such. B. Triethylamine. Tributylamine and dimethylbenzylamine. The concentration range is 2-20 mol%. based on the aromatic dihydroxy compound (s) used.

The halogen-containing polycarbonates and their mixtures with halogen-free polycarbonates are excellent for the production of foils, foils and fibers suitable, in addition to the well-known PoIycai bonate properties an improved flame resistance or incombustibility, high heat resistance and show reduced susceptibility to agents which break down carbonate bonds. Furthermore they are also used to make other plastics flame-proof.

example 1

In a reactor with a capacity of about 21, 7.15 kg'hour of a 1 solution

4300 g of tetrabromobisphenol A. 45 g of tribromophenol.

2 g sodium borohydride (common reducing agent in polycarbonate manufacture). Sl g triethylamine (K) mol%. based on bisphenol).
2135g 45% sodium hydroxide solution and 22 kg water

reacted with 287 g / hour phosgene with the addition of 9 kg hour methylene chloride at about 25 ° C. The pH value is around 7.

In the first tank of the three-stage stirred tank cascade following the reactor with a total volume of approx. 121 one doses 320 ml per hour 17% sodium hydroxide solution so that a pH value of 5 is maintained.

After the reaction mixture go through the cascade the organic phase is separated off and washed free of electrolytes with water. After vaporizing of the solvent, a colorless, viscous poly carbonate with a relative viscosity is obtained , o of 1.182? measured in methylene chloride at 25 ° C

"^ The content of saponifiable chlorine is 4ppm. The aqueous reaction phase is free from tetrabromobisphenol A, this means a quantitative conversion of the bisphenol.

Example 2

7.8 kg / hour of a solution are obtained under the same apparatus conditions as in Example 1 3.66 kg tetrachlorobisphenol A.

14 kc water,

15 _c "tert-butylphenol,
"-) e sodium borohydride,

50e triethylamine (equal to 5 mol%. Based

on bisphenol),
2.5 kg of 45% sodium hydroxide solution

reacted with the addition of 8.5 kg of methylene chloride with 321 g / hour of phosgene at about 24 ° C. The pH value T ^ the first pot of the cascade is dosed 470 g 17% sodium hydroxide solution, whereby the pH value rises to 13.4 • After the reaction mixture the cascade

is has passed through, it is as described in Example 1

"Worked up. Relative viscosity 1.18.

Example 3

.0 Under the same apparatus conditions as in Example 1, 6.9 kg / hour of a solution of 2170 g of tetrabromobisphenol A, 910 g of bisphenol A,
~> g sodium borohydride,
60 g of triethylamine (equal to 7.5 mol%. Based

on bisphenols),
30 g tert-butylphenol,
2110 g 45% sodium hydroxide solution,

22 kg of water.

Reacting with the addition of 9 kg / hour of methylene chloride at about 22 ° C. with 266 g / hour of phosgene. The pH value in the reactor is 8

290 ml / hour of 17% sodium hydroxide solution are metered into the first pot of the stirred tank cascade, whereby the pH rises to 14.0.

Working up is carried out as described in Example 1. Relative viscosity 1.21; Bromine content:

38.8%.

Example 4

Under the same conditions as in Example 1, 9.9 kg / hour of a solution are grounded out

1.78 kg bisphenol A.

6.66 kg tetrachlorobisphenol A.

71.1 kg "water.
6.1S kg of caustic soda.

52.5 g of p-tert-butylphenol.
5 g sodium borohydride,

52.5 g triethylamine (2 mol%, based on bisphenol)

reacted with 0.355 kg / hour of phosgene with the addition of 9.5 kg / hour of methylene chloride / chlorobenzene 60/40. The pH value is 8.5.

Dose into the first mixing bowl of the cascade 0.17 kg / hour sodium hydroxide solution 45%, and 300 g of 2% aqueous triethylainin solution (2 mol%, based on Bisphenol). The pH is 13.8.

The further reaction and the work-up are carried out analogously to Example 1. Relative viscosity: 1.25. Inorganic and saponifiable chlorine 8 ppm. Chlorine content: 28.4%.

Claims (1)

Patent claims: 1. Process for the production of polycarbonates from aromatic dihydroxy compounds, of which 50-100 mol% are bisphenols of the following general formula are: with 1 to 6 carbon atoms, cycloalkylene. Cycloalkylidene with 5 to 15 carbon atoms. Single ignition, - O -, - S -, - SO -, - SO, --— CO-