DD218104A1 - METHOD FOR PRODUCING THERMALLY STABLE CELLULOSE AMINE OXIDE SOLUTIONS - Google Patents

Abstract

The invention relates to a process for the preparation of thermally stable cellulose-Aminoxidloesungen, which can be used for the deformation of regenerated cellulose. The object and the object of the invention are to eliminate the problems associated with the thermal instability of the amine oxides and the degradation of the cellulose in amine oxide solutions. According to the invention, one or more basic substances are added to the amine oxide in amounts of between 0.1 and 10% by weight, based on the cellulose solution. The invention can be used for the production of fibrous materials, films or other forms of regenerated cellulose.

Description

Title of the Invention '.'

Process for the preparation of thermally stable cellulose-amine oxide solutions

Field of application of the invention

The invention includes a process for preparing thermally stable cellulose-amine oxide solutions necessary for the deformation to Regenerätfaserstoffen, films or other -fortngebilden _f n can be used.

Characteristic of the known technical solutions

It is known that certain amine oxides, e.g. N-methylmorpholine-N-oxide, N-methylpiperidine-N-oxide or N, N'-dimethylethanolamine-N-oxide, or aminoxide-containing mixtures are solvents for cellulose (U3-PS 2 I79 181, US Pat. No. 3,447,939) ,

Forming of regenerated cellulose can be produced from these solutions by suitable deformation and regeneration in precipitation baths (DD-PS 140 257, DE-OS 2 830 684).

It is also known that these amine oxides decompose starting at temperatures above 170 C and above 200 ⁰ C at starker'Wärmeentwicklung explosively with release of gaseous products

(Cope, αmer, formerly Soc., I960, 4656) and that in the presence of iron, iron oxide and especially of iron salts or similar heavy metal compounds accelerates the decomposition reaction and the decomposition temperature is reduced to about 130 ° C (Ferris, 0. Org. Chem., 1968, 33 (9), 3493).

Due to this fact, the production and deformation of Cel-ulose-amine oxide solutions, which takes place at temperatures of 100-130 ⁰ C (DD-PS 140 257, 140 258, .140 356, 142 89.8, DE-OS 3 034 685) with risks.

Since for the application of aminoxides for the production of cellulose deformation products the most complete cycle management of the solvent for economic and technological reasons is necessary, resulting from the thermal instability of the amine oxides in this procedure, a further disadvantage.

In addition, with increasing. Temperature, dissolution and processing time, a reduction of dissolved in the amine oxide cellulose instead. The degradation of the cellulose is considerably increased in the presence of certain impurities, in particular iron and its compounds. Excessive cellulose degradation negatively affects the properties of the moldings obtained from these cellulose solutions.

To reduce the cellulose degradation in aminoxide-containing cellulose solutions, a method is described in which the solution or the amine oxide various substances are added, which have a reducing effect on amine oxide (DD-PS 158 656).

According to DE-OS 3,034,685, a depolymerization of the cellulose in aminoxidhaltigen solutions by addition

strongly reduced organic Verbindungen having at least 4 carbon atoms, / at least -2 conjugated Poppelbindungen and at least 2 hydroxyl and / or amino groups having at least one unsubstituted hydrogen atom and / or glyceraldehyde.

Oer disadvantage of this method is that / it comes to a discoloration of the cellulose solutions or accumulate in the circulation of the amine oxides reaction products of said additives. In addition, the additives can not effectively prevent the additional cellulose degradation catalyzed by iron compounds and other impurities.

Object of the invention

The object of the invention is the development of a process for the preparation of thermally stable cellulose-aminoxide solutions, which makes it possible to produce regenerated cellulose shaped bodies with sufficiently high degree of polymerization from solutions in amine oxide with minimal tendency to decompose.

Presentation of the invention of the invention

The object of the invention is to eliminate the men associated with the thermal instability of the amine oxides and the degradation of cellulose in amine oxide.

According to the invention the object is achieved by applying a method for producing thermally stable cellulose-amine oxide solutions with reduced cellulose degradation, in which the amine oxide in its preparation and / or during and / or after the dissolution of the cellulose in the amine oxide one or more

4 -

basic substances in amounts between 0.1 and 10 fias-3Θ / 0, based on the cellulose solution, are added.

The organic substances can already be added to the reaction product of tertiary amine and oxidizing agent obtained in the preparation of the amine oxide before concentration into the amine oxide melt and before the addition of cellulose.

Further, addition of the basic substances to an amine oxide-cellulose mixture in the solid state before the reflow process or to an amine oxide-cellulose solution in the molten state is possible.

The basic substances used can be alkali metal hydroxides, basic salts and organic nitrogen bases.

The erfirtdungsgemäße method has the advantage that manufactured with considerably reduced risk of thermal decomposition of the amine oxide cellulose solutions therein and at temperatures of 100 - 130 ⁰ C may be deformed. Furthermore, the solvent losses are greatly minimized in the circulation leadership of the amine oxides for the production and deformation of cellulose solutions. -

A further advantage of the invention is that the basic-acting additives decisively limit the degradation of the cellulose during the dissolution in the amine oxide at elevated temperature and during the processing of these cellulose solutions. The additives also effectively reduce the additional cellulose degradation caused by iron compounds and other impurities.

Embodiments Example 1-5

The investigations on the thermal stability of N-methyl-morpholine-N-oxide (NMMO) are carried out in a thermostated reaction vessel (bath temperature 150 ⁰ C) with stirring. Temper samples taken at intervals are taken up in water, and after stripping off the basic addition products, the amine oxide content is determined by reduction with zinc and measurement of the tertiary amine by analysis

example amine oxide stabilizer Amine oxide content in after tempering No. (Dimensions%) Dimensions% from times , 120 minutes 6.0 min, 94.5 1 NMMO 97.3 96.4 2 as example 0.5 % NaOH 98.5 86.5 3,; NMMO + - 90.8 1 mass% Fe powder 96.5 4 as example 3 0.5 % NaOH 100.0 93.4 5 as example 3 2.0% Na ₂ CO ₃ 97.4 92.0 6 as example 3 2.0 % phenyl 96.4 .beta.-naphthyl- amine

Example 7

In 400 g of molten NMMO are dissolved at 125. ⁰ C 4 g of pulp with a DP of 660 30 minutes. The precipitation of the cellulose is carried out by pouring the CeI-luloselösung into water. The DP, after which Cuoxammethöde determines, is 420.

- · 6 -

'Example 8

4 g of cellulose (DP 660) are dissolved in 400 g of molten NMMO at 125 ⁰ C with the addition of 1 mass% overall NaOH, based on the cellulose solution, 30 or 120 min., Dissolved. The DP of the cellulose precipitated in water after 30 minutes is 610 and the 452 precipitated after 120 minutes.

Example 9

In 100 g of molten NMHO 4 g of cellulose (DP 660) are at 105 ⁰ C for 60 min. And then dissolved precipitated in water. The DP is 470.

Example 10

In 100 g of molten NMMO 4 g of pulp (DP 660) at 105 ⁰ C for 60 min. With the addition of 2 mass ..; Na C0 "solved. The DP of the cellulose precipitated in water is 520.

Example 11 ".

In 100 g of molten NMMO 4 g of cellulose (DP 660) are at 105 ⁰ C for 60 min dissolved. The addition of 3 of ethanolamine ingot. The DP of the precipitated cellulose is 530.

Claims (6)

invention claim . 1. A process for preparing thermally stable cellulose-amine oxide solutions with reduced cellulose degradation, characterized in that the amine oxide in its preparation and / or during and / or after the dissolution of the cellulose in the amine oxide one or more basic substances in amounts between 0.1 and 10 mass ¹ ^, based on the cellulose solution, be added. 2. The method according to item 1, characterized in that the resulting in the production of amine oxide reaction product of tertiary amine and oxidizing agent prior to concentration to amine oxide melt and prior to the addition of cellulose basic substances are added. , 3. The method according to item 1, characterized in that an amine oxide-cellulose mixture in the solid state before the melting process basic substances are added zen. . 4. The method according to item 1, characterized in that the amine oxide cellulose solution in the molten state, basic substances are added. ¹ - ft _ 5. The method according to points 1 to 4, characterized in that alkali metal hydroxides are added ^x . - / 5. Method according to items 1 to 4, characterized in that basic salts are added. 7, Process according to the items 1 to 4, characterized in that organic nitrogen bases are added.