DD160546A4 - METHOD FOR PRODUCING POLYAETHERALCOOHOLES - Google Patents

Abstract

The invention relates to a process for the preparation of polyether alcohols which are used extensively in the polyurethane industry. The aim of the invention is to produce polyether alcohols in industrial amounts, in reactors of different construction. The object of the invention is to improve the overall synthesis conditions, to make the starting mixtures to be used for the polymerization more variable and to obtain the same functionality and molecular weight of the same polyether alcohols. A process for the preparation of polyether alcohols by polyaddition of alkylene oxides to polyhydric alcohols in the presence of alkaline catalysts using a homogenizing additive to the catalyst starting mixture according to Patent WP C 08g / 169728 (s), characterized in that the addition of an alkylene oxide to a mehrwetigen alcohol as a homogenizing additive in Form of its mixture with a solution of potassium alcoholate in a polyhydric alcohol in a weight ratio of 10: 1 to 1: 1 is used.

Description

description

Applicant: Dr, Wolf-Dieter HaMeher Gleb. A. Gladkovsky Dr * Vladimir StV Lebedev Ifikolai R. Danilov

Zustellungsbevollmäclitigt:

YEB Syη the se wek S chw ard the Dept. PD-PL

7817 Schwarzheide 1

a) Title of the invention; :

Terases for the production of polyether alcohols

b) Field of application of the invention :

The invention relates to a process for the preparation of polyether alcohols according to the patent γ / ρ C Λ5 £ dOG, ^ -ie in the polyurethane industry in large. Scope of application ',

c) Characteristic of the known technical solutions :

In the patent WP ( / l $ <§ ^ OG the addition of low molecular weight addition compounds of ethylene oxides to polyhydric alcohols, so-called prepolymers, as homogenizing additives to the catalyst mixture in weight ratios of 1.: 10 to 1: 1 described.

In practice, however, it has been found that the stated proportions of 'homogenizing additive (prepolymer) to catalyst mixture are sufficient to ensure a fast reaction, but technologically, for example, for the production of higher

I b LL D

-ζ-

molecular polyether alcohols is advantageous to further increase the Vorpoljnneranteil acting as a homogenizing Zusats. For this purpose, less chemical rather than physical and especially apparatus technical aspects prevail.

Thus, it is observed that homogenizing additives to the catalyst mixture in the stated weight ratios when using high catalyst concentrations, which cause a ertrem high viscosity of the catalyst starting mixture, not so strong viscosity-reducing and homogenizing act to guarantee a smooth and easily controllable process.

Due to the high catalyst concentrations, the viscosity reduction of the reaction mixture by the homogenizing additive itself and the increased solubility of the alkylene oxides in the reaction mixture, which in turn leads to a reduction of the viscosity, are partially compensated. Although the polymerization reaction proceeds rapidly, however In these cases, the metering rate for the corresponding Alkyleno ^ id be increased only slowly, since due to the higher viscosity of the Reaktionsgemischeε and the associated Durchinischungs-, Strömunge ~, transport and heat transfer problems, the rapid removal of the heat of reaction on the double jacket of the reactor, a cooling coil in the reactor or via a heat exchanger located outside the reactor, it is difficult to design su.

In many cases, the available for polymerization discontinuous reactors for the preparation λ ^ οη Polyätheralkoholen be placed with a certain molecular weight, so that it for apparative reasons, su low immersion depth of the stirrer or a minimum necessary, but relatively large circulating volume in the outside Heat exchangers., Is often not possible. to substantially lower the concentration of the catalyst mixture, thereby producing polyether alcohols having a higher molecular weight, which is also possible

192253

the use of in the patent WP. ¹ / Iix? ^ Οβ ι ) specified proportions of homogenizing additive to catalyst starting mixture in a still insufficient extent possible *

d) Object of the invention

The aim of the invention is to produce polyether alcohols in technical quantities in reactors of various construction while eliminating the abovementioned deficiencies.

e) Presentation of the essence of the invention

- The technical problem which is solved by the invention. The object of the invention is to improve the overall synthesis conditions, to make the starting systems to be used for the polymerizate variable more variable and to obtain polyathercohols of the same type and molecular weight,

Features of the invention

According to the invention, the object is achieved in that an Additi'onsprodukt of Alfcyleaoxids is used on a polyhydric alcohol as homogenizing addition to the catalyst mixture. The amount of as. homogenizing additive used prepolymer can be arbitrarily increased in relation to the catalyst mixture, preferably a solution of monoglycerate potassium in glycerol according to the conditions of the apparatus and the concentration of the catalyst, without affecting the end products of the polymerization in terms of properties.

The homogenizing additive is used in the form of a mixture with the solution of the catalyst in a polyhydric alcohol (catalyst starting mixture), preferably in a weight ratio of from 10: 1 to 1: 1, especially when using high catalyst concentrations. The application of the homogenizing additive at the indicated weight ratios to the catalyst starting mixture guarantees a sufficient even at extremely high catalyst concentrations

ib LL D ό - 4 -

Solubility of the alkylene oxide in this homogeneous Stargeiniscli and a viscosity which leads to no difficulties in the mixing of Reaktionsgemiseheε and heat removal. In addition, the amount of charge of the reactor can thus be varied within wide limits in accordance with the apparatus requirements and the polymerization reactor can be utilized for the preparation of polyether alcohols of very different molecular weights.

This method of homogenizing and lowering the viscosity of the polymerisation ti on sgemi s before transition is alcohols for any mehrv / ertige off Γ or mixtures thereof in the polymerization with Alkylenoxideη and mixtures thereof, particularly advantageous at high catalyst concentrations applicable ·

The invention will be explained in more detail below with reference to two exemplary embodiments:

Exemplary embodiment, 1:

A stainless steel reactor equipped with a jacketed jacket, cooling coil, the necessary flow and leveling equipment connected to dosing vessels for the alkylene oxides and a powerful pump with a heat exchanger is thoroughly purged with ultra pure nitrogen and with 2280 parts by weight of a solution of Monoglycerate potassium (MGK) in glycerol is charged to a catalyst content of 20 % based on potassium hydroxide; after the evacuation and heating of the reactor to 110 ° C., the propylene oxide feed is started, it being necessary to ensure that the prescribed reaction pressure and the reaction temperature are from 115 to 120 C is not exceeded. Due to the heterogeneous ^ present reaction mixture occurs a pronounced induction period of about 13 h, wherein at the beginning of the reaction, the metering rate of propylene oxide 10-50 parts by weight / h and for the total reaction of propylene oxide takes a page of 38 hours, from an average propylene oxide metering rate of 110 parts by weight / hour results. It becomes a product with a catalyst concentration of 6.6? % based on potassium hydroxide and having an average molecular weight of about 300, the stroke in a simple manner to higher molecular weights weiterpropoxy-

can be liert.

Off . Guide pig I 2 :

In experiments using the method according to the invention are given to the reactor described in Example 1 and under the conditions mentioned mixtures of a solution of monoglycerate in glycerol with a catalyst content of 20 % based on potassium hydroxide with a homogenizing additive, for example in the form of a prepolymer with a average molecular weight of about 300 and a catalyst content based on potassium hyaroxide of 68 %, in the weight ratios indicated in Table. The reaction begins immediately without an induction period and the initial metering of PropylenoxLds can be increased compared to Example 1 up to 50 times, so that under the given technical conditions average metering speeds of 500 600 parts by weight of propylene oxide per hour can be easily realized, resulting in a drastically shortening the synthesis time leads and whereby the advantage of the method according to the invention is clearly visible. According to the reactor coating amounts of MGK, VP-300 with Po listed in Table 1, products having an average molecular weight of 300 and having a catalyst content based on KOH of 6.7 to 6.9 are obtained, which are completely identical to the products prepared without homogenizing additive, and how these can be further polymerized by known processes to give higher molecular weight polyether alcohols by reaction with alkylene oxide or their mixtures,

Table 1 ;

Examples of the preparation of polyether alcohols from pure catalyst mixtures (MGK) and according to the erfindugsgemaßen process by homogenizing additives (VP-300) to the catalyst start ge mixed

a z.

MGE (GWt) 1700 2280 2280 2280 2280 1700 1700 1000 72 (

VP 300 (GWt) - - 3000 3170 1600 2770 4320 4700 705 <

PO (GWt) 3122 4200 4200 4200 4200 3122 3122 1840 132:

Relationship _ _ ^ ₃ ^ _{4 0>?} ^ _{6 ZQ} ^ ₇ VP 300 / IdGK

Svntliese-

duration (h) 31 3C 6 5,5 7 5 6,5 3 2

Claims (1)

192253 Patent claim • η 7 - A process for the preparation of polyether alcohols by polyaddition of alkylene oxides to polyhydric alcohols in the presence of alkaline catalysts using a homogenizing additive to the catalyst starting mixture according to patent WP i./IS<f ΊΟζ \, characterized in that the addition product of an alkylene oxide to a polyhydric alcohol as a homogenizing additive in the form of its mixture with a solution of potassium alcoholate in a polyhydric alcohol in a weight ratio of 10: 1 to 1: "" 1 '.