阅读说明：本技术 制备聚碳酸酯的方法-链终止剂的添加时间点 (Method for producing polycarbonates-point of addition of chain terminators ) 是由 R·巴赫曼 A·奥尔蒂斯 J·巴托洛梅 M·维尔克 J·海尔 于 2020-03-30 设计创作，主要内容包括：本发明的主题是通过相界面法由至少一种二羟基二芳基烷烃、光气、至少一种催化剂和至少一种链终止剂制备聚碳酸酯的方法,其中该方法具有低的低聚物比例和低的二-链终止剂碳酸酯比例的聚碳酸酯。根据本发明的方法的特征在于,在特定的时间点将链终止剂添加到反应体系中。(The invention relates to a method for producing polycarbonates by the phase boundary method from at least one dihydroxydiarylalkane, phosgene, at least one catalyst and at least one chain terminator, wherein the method has a low proportion of oligomers and a low proportion of di-chain terminator carbonates. The process according to the invention is characterized in that a chain terminator is added to the reaction system at a specific point in time.)

1. A process for preparing polycarbonates by the phase interface process from at least one dihydroxydiarylalkane, phosgene, at least one catalyst and at least one chain terminator, characterized in that,

(i) introducing the at least one chain terminator into a reaction system comprising at least the at least one dihydroxydiarylalkane, phosgene and a reaction product R derived from the at least one dihydroxydiarylalkane and phosgene at a point in time at which the reaction product R is a mixture of compounds and these compounds have an average degree of polymerization of at least one unit and at most six units, the units being formed from the at least one dihydroxydiarylalkane by reaction with phosgene.

2. The process according to claim 1, characterized in that the compounds of the mixture of reaction products R are represented by the general chemical formula (I):

wherein

R₁And R₂Each, independently of the others, being H, C1-to C18-alkyl, C1-to C18-alkoxy, halogen, such as Cl or Br, or each optionally substituted aryl or aralkyl, preferably H or C1-to C12-alkyl, particularly preferably H or C1-to C8-alkyl, very particularly preferably H or methyl,

R₃is H, (C = O) -Cl or (C = O) -OH,

R₄is an OH group or a Cl group,

x is a single bond, -SO₂-, -CO-, -O-, -S-, C1-to C6-alkylene, C2-to C5-alkylidene or C5-to C6-cycloalkylidene which may be substituted by C1-to C6-alkyl, preferably methyl or ethyl, and furthermore C6-to C12-arylene which may optionally be fused with further aromatic rings comprising heteroatoms, and

n is the degree of polymerization, and thus the number of units formed by the reaction of the at least one dihydroxydiarylalkane with phosgene, and may have an average value of 1 to 6.

3. The method according to any one of claims 1 or 2, characterized in that it comprises at least one addition of an aqueous alkali metal hydroxide solution.

4. The method of claim 3,

(ii) the addition of the at least one chain terminator to the reaction system in process step (i) is carried out temporally before the first addition of the at least one addition of the aqueous alkali metal hydroxide solution.

5. Method according to any one of claims 1 to 4, characterized in that it comprises the following steps:

(a) producing a dispersion consisting of an organic phase and an aqueous phase, wherein the organic phase comprises at least one solvent suitable for polycarbonates and at least part of phosgene, the aqueous phase comprises the at least one dihydroxydiarylalkane, water and 1.8 to 2.2 mol, preferably 1.95 to 2.05 mol, of aqueous alkali metal hydroxide solution per mole of dihydroxydiarylalkane,

(b) producing in the dispersion obtained from step (a) a reaction system comprising at least the reaction product R obtained from the reaction of the at least one dihydroxydiarylalkane and phosgene by reaction of the at least one dihydroxydiarylalkane with phosgene,

(c) adding at least one chain terminator to the reaction system of step (b), wherein the reaction system of step (b) comprises unconverted phosgene, and

(d) optionally adding an aqueous alkali metal hydroxide solution at least once to the mixture obtained from step (c).

6. Method according to claim 5, characterized in that it additionally comprises the following steps:

(e) at least one catalyst is added at least once.

7. The process according to any one of claims 1 to 6, characterized in that the reaction system at the start of the reaction has an excess of phosgene of 3 to 20 mol% relative to the sum of the dihydroxydiarylalkanes used.

8. The method according to any one of claims 1 to 7, characterized in that the method is operated continuously.

9. The process according to any one of claims 1 to 8, characterized in that the at least one catalyst is chosen from tertiary amines and organic phosphines.

10. Process according to any one of claims 1 to 9, characterized in that said at least one chain stopper is chosen from phenols, alkylphenols and chlorocarbonates thereof or acid chlorides of monocarboxylic acids, preferably from phenol, tert-butylphenol and isooctylphenol, cumylphenol.

Examples

The molecular weight distribution and the mean values Mn (number average) and Mw (weight average) were determined by means of Gel Permeation Chromatography (GPC). The instrument comprises the following steps: waters "Mixed Bed" column) with methylene chloride as eluent (using a BPA homopolycarbonate standard with an Mw of 31000 g/mol).

In addition to the routine evaluation, the deviation of GPC from the ideal Schulz-Flory distribution was also determined. For this purpose, the GPC is first normalized, so that the area under the solid line of the curve of fig. 1 is obtained. The area is normalized to 1. Furthermore, the Schulz-flory (sf) distribution was adjusted such that its maxima in height and molecular weight were consistent with the measured distribution (dotted line in fig. 1). The difference between the measured and adjusted SF distribution gives the difference distribution (dashed line in fig. 1). In the present case, the Schulz-Flory distribution is narrow, so the differential distribution is positive (except for measurement inaccuracies). Due to this method, the difference at the maximum is zero, so the difference distribution is broken down into a low molecular weight fraction and a high molecular weight fraction (see also fig. 1 for this).

It is known from the prior art that a high oligomer proportion is detrimental to the product quality. However, only the total proportion of low-molecular-weight compounds or the proportion soluble in acetone below certain limits is generally taken into account here. This has the disadvantage that unavoidable oligomer proportions are also taken into account, which proportions also vary with the type of polycarbonate (viscosity, Mn). The method of the invention corrects for this dependence and determines only the method-specific oligomer ratio.

2,2' -bis- (4-hydroxyphenyl) propane (bisphenol A, BPA) was used as the dihydroxydiarylalkane, and the solvent for the organic phase was a mixture of about 50% by weight of methylene chloride and 50% by weight of monochlorobenzene. Polycarbonates having the stated weight average molecular weights were prepared in all examples and were measured by GPC (Waters "Mixed Bed" column in methylene chloride with BPA homopolycarbonate standard having an Mw of 31000 g/mol).

Example 1 difference in the time points of addition of chain terminators

Continuous laboratory experiments were conducted in a combination of pump and stirred reactor. In all experiments 70.1 g/h of gaseous phosgene were dissolved in 772 g/h of organic solvent (1: 1 dichloromethane/chlorobenzene) in a T-tube at-7 ℃. The amount of solvent was calculated to finally obtain a 15 wt% polycarbonate solution. The phosgene solution fed continuously was contacted in a further T-piece with 912g/h of a 15% by weight aqueous alkaline BPA solution (2mol NaOH/mol BPA), which had been preheated to 30 ℃. The BPA solution was dispersed in the phosgene solution (pore size 60 μm) through a stainless steel filter.

The reaction mixture was conducted to a Fink HMR040 mixing pump which was tempered at 25 ℃ so that phosgene had reacted as completely as possible at the end of the reaction pump, but was still present. After the pump, atExamples 1a, 1c and 1d3.29 g/h of p-tert-butylphenol as 3% by weight solution were metered into the same solvent mixture as described above as chain terminator and the reaction mixture was further reacted with 53.95g/h of 32% by weight aqueous sodium hydroxide solution at 25 ℃ in a further HMR040 pump to give a pH at the end of the reaction system of about 11.5. In thatComparative example 1b3.29 g/h of p-tert-butylphenol as a 3% by weight solution were added here as chain terminator to the same solvent mixture as described above.

This is followed by 2 stirred tanks from Ismatec with one gear pump each. 0.679 g/h of catalyst (10% by weight of N-ethylpiperidine dissolved in chlorobenzene) are metered in between two stirred tanks (and gear pump) in a T-piece in a Teflon hose.

A total of 156g of polycarbonate in organic solution were obtained continuously and passed together with the aqueous phase from the reaction into a phase separation vessel for separation. The polycarbonate solution was washed with 10% by weight HCl and dried at normal pressure and room temperature.

Table 1 summarizes the results obtained in example 1:

TABLE 1

	Excess of phosgene	Mn 0	T device	Diff. id. MGV (PC)	Di-chain terminator carbonate (PC)	CO3	Mn (PC)	Mw (PC)
										%	g/mol	℃	Area%	ppm	By weight%	g/mol	g/mol
Example 1a	16.2	750	35	2.72	< 50	0.65	10 580	26 980
									Comparative example 1b	16.2	3470	35	8.10	< 50	0.65	7870	26 160
Example 1c	9.5	660	25	2.78	< 50	0.38	9800	26 200
									Example 1d	7	730	25	2.50	< 50	0.33	9990	25 300

Mn0 molecular weight when chain terminator was added

Diff id. MGV (PC) differential distribution; see the explanation above.

Example 1a shows the addition of a chain terminator at the point in time when the reaction product R comprises a mixture of compounds having an average molar mass Mn0 of 750 g/mol. In comparative example 1b, the chain terminator was added at the point in time at which the reaction product R contained a mixture of compounds having an average molar mass Mn0 of 3470 g/mol. In examples 1c and 1d according to the invention, the phosgene excess was reduced and a chain terminator was added at the point in time at which the reaction product R contained a mixture of compounds having an average molar mass Mn0 of 660 or 730 g/mol. It can be seen that the polycarbonates obtained in each case contain a low proportion of double chain terminator carbonates. However, the polycarbonates according to the examples of the invention also have significantly lower oligomer values (measured by Diff id. MGV).

In comparative example 1b, the addition of NaOH is carried out temporally before the addition of the chain terminator. However, the addition of the chain terminator proceeded so early that phosgene was therefore assumed to be still present in the reaction system.

The addition of a chain terminator at a point in time when phosgene is no longer present in the reaction system would mean that the reaction product R has on average an even higher molecular weight. Even higher proportions of oligomers are thus to be expected.

Example 2

The devices used as individual method steps:

method step (A) A disperser in the form of an orifice nozzle with pre-dispersion (orifice plate with 5 bores each 2.5 mm in diameter, orifice plate thickness 2.35, pressure drop 0.2 bar at a flow rate of 5.2 m/s), residence time in the pre-dispersion space of 26 ms and subsequent dispersion (orifice plate with another 18 bores each 1.5 mm in diameter, orifice plate thickness 2.35 mm, pressure drop 0.8 bar at a flow rate of 8.9 m/s) is liquid dispersed in the other by one.

Process step (B) residence time reactor with residence time 0.2 s.

Method step (C) A recirculating pump reactor equipped with metering-in points (for example for NaOH; here, in comparative experiment 2b, 20% of the NaOH used is added), a pump, a heat exchanger, an overflow vessel and a T-shaped take-off point, having a volume of 140 l, with a pH probe and a conductivity probe; redispersing the mixture when the mixture enters a circulating pump reactor; in experiment 2a, chain terminator was added to the circulating pump reactor.

Process step (D) with a discharge pump for the metering point upstream of the chain terminator (chain terminator added here in comparative experiment 2 b; nothing added here in experiment 2 a) and of the NaOH solution, with a static mixer in between, downstream of a serpentine reactor with a mixing zone and a residence zone and a total volume of 60 liters (first residence reactor), and downstream of another serpentine reactor with a metering point for the catalyst at the beginning of the reactor and a total volume of 80 liters (second residence reactor).

Subsequent phase separation in a separation vessel (size 4.15 m)³Fill level 50%).

The following streams were used in process step (a):

600kg/h of an aqueous bisphenol solution (15% by weight mixture of bisphenol A and bisphenol TMC, based on the total weight of the solution, 2.13mol NaOH/mol bisphenol solution)

44.6 kg/h phosgene

520 kg/h of a solvent mixture of 54% by weight of methylene chloride and 46% by weight of chlorobenzene

No additional streams are additionally used in process steps (B) and (C).

In process step (D), the following streams are additionally used before the first residence reactor:

17.8 kg/h of a tert-butylphenol solution (20% by weight in a solvent mixture of 54% by weight of methylene chloride and 46% by weight of chlorobenzene)

35 kg/hNaOH in water having 32% by weight of NaOH

In process step (D), the following streams are additionally used in the second residence reactor:

22.7 kg/h catalyst solution (3% by weight solution, ethylpiperidine in a solvent mixture of 54% by weight dichloromethane and 46% by weight chlorobenzene).

The temperature in the circulating pump reactor was 35 ℃ (after the heat exchanger) to 38 ℃ (before the heat exchanger). The temperature in the serpentine reactor in process step (D) was 37 ℃ and the temperature in the disengaging vessel was 35 ℃.

The direction of dispersion is set such that the organic phase is dispersed in the aqueous phase.

Table 2 summarizes the results obtained.

TABLE 2

	MnLoop	T device	Diff. id. MGV	Di-chain terminator carbonate (PC)	CO3	Mn (PC)	Mw (PC)
									g/mol	℃	Area%	ppm	By weight%	g/mol	g/mol
Example 2a	< 900*	60	3.50	200	0.75	12 017	31 650
								Comparative example 2b	2320	60	5.00	< 50	0.76	10 244	29 030

Estimated value

MnLoop molecular weight at addition of chain terminator

Diff id. MGV (PC) differential distribution; see the explanation above.

Example 2a shows the addition of a chain terminator at a point in time when the reaction product R comprises a mixture of compounds having on average a molar mass Mn Loop of less than 900 g/mol. In comparative example 2b, the chain terminator was added at the point in time when the reaction product R contained a mixture of compounds with an average molecular weight Mn Loop of 2320 g/mol.

It can be seen that in the examples according to the invention the polycarbonates obtained have a higher proportion of di-chain terminator carbonates than in comparative example 2 b. However, the content is within an acceptable range. However, the examples according to the invention have significantly lower oligomer values (measured by Diff id. MGV).