DD254387A1 - METHOD FOR PRODUCING POLYURETHANE RAW MATERIALS - Google Patents

Abstract

The invention relates to a process for the preparation of polyurethane raw materials by condensation of predominantly aromatic amines and formaldehyde, which are suitable for use in polyurethanes. The object of the invention is the development of a process for the preparation of polyurethane raw materials by condensation of amines with formalin, which leads to condensates of low viscosity and thus allows the processing of these products into polyurethanes with a high aromatics content. According to the invention, the object is achieved in that the amine used is a mixture of aromatic and cycloaliphatic amines with a small proportion of aliphatic and cycloaliphatic alcohols.

Description

Field of application of the invention

The invention relates to a process for the preparation of low viscosity polyurethane raw materials obtained by condensation of predominantly aromatic amines and formaldehyde.

Characteristic of the known state of the art

Polyurethane raw materials, which are formed by condensation of predominantly aromatic amines and formaldehyde, have been known for several decades (Federal Republic OS 2623681). This synthesis is dominated by the synthesis of substances with maximum NH functionality. This goal is usually achieved by using strongly acidic homogeneous or heterogeneous rearrangement catalysts, which often have to be used in almost stoichiometric amounts. The conversion of aromatic amines with formalin to polyurethane raw materials can be simplified by the following three stages:

1. condensation,

for example, 20-NH ₂ + CH ₂ O = O-NH-CH ₂ -NH-O + H ₂ ON, N'-dianilinomethane

2. first transfer step,

for example, O-NH-CH ₂ -NH-O = O-NH-CH ₂ -Ct-NH ₂ aminobenzylaniline

3. second rearrangement stage,,

for example, 0-NH-CH ₂ -O-NH ₂ = NH ₂ -O-CH ₂ -O-NH ₂ diphenylmethanediamine

A large number of process variants has already been proposed, which relate in particular to possibilities for obtaining certain ratios of isomers in the end product, to technological features and to the use of specific catalysts (Federal Republic of Germany OS 1793137).

Thus, inter alia, it has been proposed to carry out the first stage of the reaction without a catalyst and to add the catalyst only after phase separation and to minimize catalyst consumption by extraction processes with recycling of the catalyst extracted from finished products into the reaction (DDR-PS 125220).

The substances thus obtained are mainly processed by phosgenation to polyisocyanates, in addition, however, the use wins as a starter component for Polyetheralkoholsynthesen, as a chain extender, as a raw material for the production of thixotropic agents and starting material for dispersions growing importance. In the latter fields of use, the aromatics content of these polyurethane raw materials, which leads to good temperature resistance, good mechanical properties and hydrolysis resistance in the finished product, is of particular interest. Unfortunately, this positive aspect is offset by unfavorable properties of these polyamine mixtures, such as the often solid state of matter and their high viscosity, which is also reflected in the reaction products. The result of this is that the high aromatics contents which are required for the realization of certain polyurethane properties can not be achieved in practice or can only be achieved at the cost of expensive and unfavorable manipulations with regard to the functionality of the product. Such manipulations are, for example, the use of viscous and thus usually functional-lowering, often expensive co-starters in Polyetheralkoholsynthesen and the use of technologically complex prepolymer process in the production of polyurea dispersions.

Object of the invention

The aim of the invention is to develop a process for the preparation of polyurethane raw materials with a high aromatics content and low viscosity with the exclusion of acidic catalysts.

Explanation of the essence of the invention

The object of the invention is the development of a polyurethane raw material from amines and formaldehyde, which leads to condensates of low viscosity and thus allows the processing of these products into polyurethanes with a high aromatic content.

According to the invention the object is achieved in that the polyurethane raw material is a condensation product of formaldehyde and an amine mixture

0.5 parts to 95 parts aniline

0.1 part to SB of cyclohexylamine

0.5 parts to 35 parts of cyclohexanol

0.05 part to 10 parts of aliphatic alcohol, especially methanol and / or ethanol 0.1 part to 5 parts of aniline derivatives, in particular N-methylaniline, N-ethylaniline and / or toluidine 0.01 parts to 1 part of nitro compounds and cycloaliphatics, such as cyclohexanone 0.1 Divide up to 50 parts of other aromatic amines, such as amines of the diphenylmethane series and toluenediamines and optionally water to saturation of the mixture.

By using the amine mixture according to the invention, it is surprisingly possible. Condensates with significantly reduced viscosity to produce, although the amine mixtures of the composition according to the invention, inter alia, be discharged precisely because it is expected that they give verhärende in the reaction with formaldehyde and therefore higher viscosity products.

Due to the low product viscosities of the reaction products of the invention, it is now even possible to stop the reaction on the first reaction stage (Aminobenzylaniline) and already use these products as a polyurethane raw material.

The end of the products of the first reaction stage as polyurethane raw material is not common in the prior art because of high viscosity or solid state, but is extremely advantageous for the polyurethane material due to the per NH functionality extremely high aromatics (0.67 moles of aromatics pro NH for aminobenzylaniline, 0.50 mole of aromatics per NH for diphenylmethanediamine).

The inventively opened possibility for processing the Aminobenzylanilinstufe three more significant advantages.

First, it becomes possible to produce from aromatic amines and formaldehyde, even with the exclusion of acidic catalysts polyurethane raw materials, whereby the technological complexity can be significantly reduced. This creates an important prerequisite for the lucrative industrial utilization of "waste amines", which are obtained, for example, as distillative precursors and bottoms in aniline syntheses or as rejection products in conventional polyamine synthesis.

Secondly, the possibility of using aminobenzylanilines (that is to say products having about 30% higher equivalent weight than diphenylmethanediamines) results in a very high specific use coefficient of the product in the reaction with isocyanates or alkylene oxides.

Third, the comparatively low viscosity of the condensates according to the invention is also reflected in their secondary products, resulting in further positive application-technical aspects in the preparation of, for example, dispersions, polyols, thixotropic agents and isocyanate components.

embodiments

A) Comparative Example

To 750g aniline 250g commercial aqueous formalin solution are added dropwise at room temperature in a laboratory stirrer with thermometer and dropping funnel. Then the mixture is allowed to react for 2 hours at 100 ⁰ C, adds 6 g of aqueous 48% potassium hydroxide added and stirred for 15 minutes well. After phase separation, a white crystalline substance is recovered.

B) embodiment

In a laboratory stirrer with thermometer and dropping funnel 750 g of a mixture are presented according to claim 1 and treated dropwise at room temperature with 250 g of commercial aqueous 37% formalin solution, so that a temperature of 50 ⁰ C is not exceeded. Then left to the mixture for 2 hours at 100 ⁰ C react, then add 6 g of 48% ^Wr - "3ßrige potassium hydroxide are added and stirring is continued for 15 minutes by a good After the phase separation was completed by standing, vvird the organic phase at room temperature.. a yellow liquid having a viscosity of 48mPas at 55 ⁰ C

represents, gc -. ». ^ ™ ^.

The advantage de. _The use of aniline mixture according to claim 1 is clear. The result is a liquid product lower

Viscosity, w; h _renc | in the case of analogous processing of pureaniline (A), a solid is obtained.

Exemplary embodiment; _e | 2

A) Comparative Example

325g aniline are in a labu ,. Introduced with a thermometer and dropping funnel and treated dropwise with 175 g of 37% commercial aqueous Formalinlosu. After a temperature treatment of 100 ° C over a period of 2 hours, 3 g of 48% aqueous KäY.'iteNge are added to the mixture and after Abtrena; gi ¹ Jp: '.O / Äß'r'qen phase, the organic phase becomes 5 Hours refluxed. The result is a slightly yellow-colored product with a viscous. "^ * Of 610mPasbei25 ° C. ^.:

embodiment

In a laboratory stirred apparatus with thermometer and dropping funnel 325 g of a mixture according to claim 1 are added dropwise with 175 g of 37% a handelsü books aqueous Forma linlösu ng. After a reaction time of 2 hours at 100 ⁰ C 3 g of 48% aqueous potassium hydroxide are added to the reaction mixture, and the product is boiled for 5 hours at reflux. The result is a yellow liquid with a viscosity of 225mPas at 25 ° C.

 By using the amine mixture according to the invention, in turn, a polyurethane raw material of low viscosity is obtained.

Embodiment 3

In a laboratory stirrer with thermometer and dropping funnel 325 g of a mixture are presented according to claim 1 and treated dropwise at room temperature with 175 g of commercial aqueous formalin solution and stirred at 100 ⁰ C over a period of 3 hours. Subsequently, the aqueous phase is separated and the organic phase is a light brown liquid with a viscosity of 132mPas at 25 ⁰ C, which makes the particular advantage of the amine compound use clear.

Embodiment 4

350g of a mixture according to claim 1 are added dropwise in a laboratory stirred apparatus with 150 g of commercial aqueous 37% formalin solution. Over a period of 2 hours at a temperature of 90 ° C, the reaction takes place. Subsequently, the reaction product is mixed with 1 g of 48% aqueous potassium hydroxide solution and the organic phase separated. This is rearranged for 5 hours at reflux temperature with the addition of 1 g of concentrated hydrochloric acid. The final product is a light brown liquid with a viscosity of 40 mPas at 25 ° C., which is particularly advantageous for further processing.

Embodiment 5

750 g of an amine mixture according to claim 1 are added dropwise with 350 g of commercial 37% aqueous formalin solution and 6 g of 48% aqueous potassium hydroxide solution. The mixture is stirred for 30 minutes at 100 ⁰ C and at 80 ° C, the phase separation is completed. The organic phase is a liquid with a very advantageous viscosity of 18mPa.s at 40 ° C.

Embodiment 6

In a Laborrührepparatur 1 625g of a mixture according to claim 1 are added dropwise with 875g commercial 37% aqueous formalin solution and stirred for a period of 2 hours at a temperature of 100 ⁰ C. Subsequently, the solution is mixed with 15 g of 48% aqueous potassium hydroxide solution and stirred briefly. After phase separation, the organic phase is thermally refluxed for 6 hours and then neutralized with 12.7 g of concentrated hydrochloric acid. After a vacuum treatment to remove the residual water, a brown liquid is formed with the following characteristics:

Density: = 1.106 g / cm ³

(at 25X)

Viscosity: = 2109mPas (at 25 ⁰ C)

Refractive index: 1.6252 (at 25 ⁰ C)

Claims (1)

Process for the preparation of polyurethane raw materials by condensation of aromatic amines and formaldehyde at a molar ratio of amine to formaldehyde greater than 1.2 optionally with the addition of further reactants and catalysts, characterized in that the amine 0.5 parts to 95 parts aniline 0.1 parts to 55 parts of cyclohexylamine 0.5 parts to 35 parts of cyclohexanol 0.05 parts to 10 parts of aliphatic alcohol, in particular methanol and / or ethanol 0.1 parts to 5 parts of aniline derivatives, in particular N-methylaniline, N-ethylaniline and / or toluidine 0.01 parts to 1 part of nitro compounds and other cycloaliphatic, such as cyclohexanone , 1 part to 50 parts of further aromatic amines, such as amines of the diphenylmethane series and Toluylenediamines and optionally water to saturation of the mixture is used.