SK111796A3 - Manufacturing process of carbamate of cellulose - Google Patents

Abstract

Cellulose carbamate is obtd. from opt. degraded cellulose by subjecting 1 pt. wt. cellulose (esp. as flakes) to alkaline reaction with 0.1-3 pts. urea (or salt). The reaction is effected in presence of a synergistic activating system comprising gaseous anhydrides of (in)organic acids and 0.001-10 pts. wt. (per 100 pts. wt. cellulose) of salts of (in)organic acids. The reaction occurs at 130-170 deg C for 10-600 mins., with the prod. opt. being purified. Pref. the anhydrides in the activating system are CO2, SO2, CO and/or acetic anhydride, while the salts are Na-acetate, -formate, -carbonate or -sulphate, urea-formate or -acetate and/or Co(II)-formate or -acetate. The components of the activating system can be introduced separately, together or with the urea (or salt), such introduction into the cellulose being by mixing or soaking for 1-600 mins. at 20-60 deg C. Alternatively, the salts of the actuating system can be introduced into the cellulose in the course of a neutralisation reaction, again by mixing or soaking for 1-600 mins. at 20-60 deg C.

Description

Technical field

The invention relates to a process for the production of cellulose carbamate.

BACKGROUND OF THE INVENTION

Of the following patents: USA

2134825.

Poland

P.268418, P.269143, P.272122 and Europe EP

57105, EP 178292, and numerous publications disclose processes for the preparation of cellulose carbamate, wherein the cellulose is reacted with urea after prior treatment with alkali metal hydroxides, optionally with the addition of urea or thiourea. The reaction is carried out at 130 ° C to 155 ° C.

To remove unreacted urea and its decomposition products, the product obtained is washed several times with water.

The use of cellulose with a reduced degree of polymerization is essential in this process. Cellulose is alkali oxidized for this purpose as a result of treatment with hydroxides of suitable alkali metals.

From patent documents: Finland no. 61033, United

UK No 2164941, DDR no.

201908.

No.

No. 214135 and U.S. Pat.

4404369 is also a known process in which cellulose is subjected to beta- or gamma-irradiation at a dose in the range of 0.5 to 10

Mrad until an average degree of polymerization of about

400th

The pulp obtained is treated with liquid ammonia dissolved in the urea to increase the reactivity of the pulp and allow the urea to enter the polymer.

Structure.

The physical mixture of pulp and urea is then heated above

130 -C.

From Polish patent no. No. 159085 is a known process for producing cellulose carbamate in which the pulp is subjected to enzymatic degradation by glucanases, wherein the average degree of polymerization is reduced to 300-700. The partially pulp is exposed to liquid ammonia.

% containing 1 wt. % urea. The excess ammonia is then evaporated and the resulting physical pulp / urea mixture is heated at 130-160 ° C for 30-600 minutes.

From Polish patent no. No. 160863 discloses a process for producing cellulose carbamate by reaction between cellulose and urea, wherein optionally partially decomposed pulp is activated with ammonia gas, then the urea is either in solution or solid state introduced into the cellulose structure and the physical mixture of pulp and urea is heated to 130-170. C:

From Polish patent no. No. 160866 is also a known process for producing cellulose carbamate, wherein the pulp is treated with urea in the presence of cobalt salts, e.g. cobalt (II) acetate or cobalt (II) citrate. The urea pulp mixture is then activated with ammonia gas and heated to 130-170 ° C. In one version of the process, the activation of the pulp with ammonia gas and saturation with urea in the presence of cobalt salts.

In two Polish patents no. 163049 and no. P.289890 describes two methods for producing cellulose carbamate. According to the first of these patents, the pulp is treated with urea or its salts and salts of organic and / or inorganic bases and acids, respecting the weight ratio of pulp to salt in the range of 1: 0.1 to 1: 1, and pulp to urea. or a salt thereof in the range from 1: 0.1 to 1: 2. The physical mixture is then heated to a temperature of 130 ° C to 170 ° C. The method according to the second of these patents consists in treating the pulp with an alkaline reaction with urea or its salts and an organic and / or inorganic acid, maintaining the weight ratio of pulp to acid in the range from 1: 0.15 to 1: 0 3 and a weight ratio of pulp to urea or its salts in the range of 1: 0.1 to 1: 2.

From Polish patent no. 165916 also discloses a process for the production of cellulose carbamate, which comprises gaseous anhydrides of inorganic and / or organic acids and urea or salts thereof affecting the pulp with an alkaline reaction at 130-170 ° C.

In cellulose carbamate processes that involve the use of liquid ammonia, a low temperature of about -35 ° C and the use of complex pressure and safety devices is essential, which greatly hinders the production process. The use of liquid ammonia poses a danger to personnel, equipment and the environment and greatly increases production costs. In addition, the cellulose carbamate of this process exhibits incomplete solubility in aqueous alkaline solutions.

The known processes for producing cellulose carbamate, which are based on the activation of pulp by alkali metal hydroxides, do not offer the possibility of producing products with satisfactory solubility in aqueous alkaline solutions without the formation of gels. This, together with the inhomogeneous substitution of carbamate groups, prevents the use of these products in the manufacture of spinning solutions.

In contrast, processes for the production of cellulose carbamate in which the activation of cellulose consists in introducing organic or inorganic salts or mixtures thereof into the cellulose structure or in the formation of these salts by treating the alkaline pulp with acids, entails the need for large quantities of chemicals. corrosion apparatus. In addition, the formation of the reaction-activating salts takes place unevenly in the pulp structure and leads to an inferior product.

In known methods, the production of cellulose carbamate-forming fiber with a homogeneous substitution of carbamate groups, with good solubility in aqueous alkaline solutions and good stability of these solutions, is not guaranteed.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the preparation of cellulose carbamate, wherein the pulp, preferably in flakes and with an alkaline reaction, is treated with urea and / or its salts in the presence of a synergistic catalyst system. This system consists of gaseous anhydrides of organic and / or inorganic acids and salts of organic and / or inorganic acids. These salts are used in the percentage of pulp to urea from. 0.001 to 10%, while the weight ratio of pulp to urea and / or salts thereof ranges from 1: 0.1 to 1: 3. The mixture is then heated in a temperature range of 130 to 170 ° C for 10 to 600 minutes. The cellulose carbamate obtained is optionally subjected to purification.

Carbon dioxide, sulfur dioxide, carbon monoxide and, as salts, sodium acetate, cobalt formate, sodium carbonate or sulfate are used as gaseous anhydrides in the process of the invention.

The components of the synergistic catalyst system are added to the pulp, singly or together with urea or its salts, by admixing or saturating at 20-60 ° C for 1-600 minutes.

When an alkaline reaction pulp is used in the process of the invention, salts that form a synergistic system can be formed in the pulp by neutralizing the pulp with organic or inorganic acids such as acetic acid, formic acid, sulfuric acid and / or acid anhydrides such as oxide carbon dioxide or sulfur dioxide. Acids and / or anhydrides are added to the pulp by mixing or saturating at 20-60 ° C for 1-600 minutes.

The synergistic system used to activate the reaction between cellulose and urea used in the process of the present invention forms the corresponding second order compounds with the cellulose hydroxyl groups and thereby permits their uniform conversion with the carbamate groups. These compounds also allow for much better penetration of urea into the cellulose structure than prior art methods. This produces cellulose carbamate fibers with very good solubility in sodium hydroxide. The obtained alkaline cellulose carbamate solutions exhibit high stability even at temperatures above 5 ° C, at which known cellulose carbamate solutions are rapidly gelled. Accordingly, the use of a synergistic, activating system facilitates, on the one hand, the penetration of urea into the interior of the cellulose structure and, on the other hand, allows a uniform substitution of hydroxyl groups by carbamate groups. As a result, the resulting cellulose carbamate exhibits a high degree of uniformity of substitution with a direct effect on the good spinability of the cellulose derivative thus produced. The synergistic action of the components of the synergistic cellulose-activating system allows, in addition to influencing the uniformity of substitution of carbamate groups, a simplification of the synthesis process with respect to technology and apparatus. In addition, the form of the pulp used in the leaves without grinding facilitates the synthesis process. The product obtained in the leaves is well suited for immediate use as well as for transport. The cellulose carbamate produced according to the invention is characterized by a nitrogen content in the range of 1 to 3% and the ability to form alkaline spinning solutions with a viscosity of 100 seconds and a filter factor Kw * significantly below 50.

Cellulose carbamate with such properties is well suited in the chemical fiber industry for transformation into cellulose fibers and films as well as for the production of other technical products.

The process of the present invention will be illustrated by the following examples. These examples do not limit the scope of the invention.

Example 1 parts by weight of Modo Crown pulp in leaves, with a degree of polymerization of DP = 651, is exposed in the press to 210 parts by weight of 18% sodium hydroxide solution at 21 ° C for 1 hour. The excess liquor is then drained off and the resulting alkaline cellulose is pressed to a compression factor of 2.1. The alkaline cellulose leaves are then ground in a roll-off roller for 2 hours. The ground alkaline cellulose is saturated with carbon dioxide for 1 hour until the sodium hydroxide contained therein is completely neutralized. Then 1 part by weight of anhydrous acetic acid and 25 parts by weight of urea are added; the contents of the mixing vessel are stirred for 1 hour. The mixture is heated for 90 min at 135 ^e C and then for cleaning several times with water at 40 and then dried. 26 parts by weight of cellulose carbamate are produced having the following properties:

Color - light gray-yellow, bound nitrogen content - 1.4%, DP = 201. The product was perfectly soluble in 9% sodium hydroxide solution. The solution was stable at 16 ° C with a Kw roztoku value of solution -5.

Example 2

23.5 parts by weight of pulp of the same quality as in Example 1 are alkalinized under the conditions of Example 1. The resulting alkaline cellulose is compressed to a degree of compression of 2.7 and subsequently ground for 2 hours. The ground alkaline cellulose was saturated with sulfur dioxide under the conditions of Example 1, and 25 parts by weight of urea acetate were added with stirring over 15 minutes. The mixture is homogenized for 1 hour at 30 ° C and then heated at 135 ° C for 90 minutes. The product obtained is purified as in Example 1.

25 parts by weight of cellulose carbamate are obtained having the following characteristics:

Color - light gray-yellow, bound nitrogen content - 1,3 X, DP = 361, good solubility of the product in 9 fc sodium hydroxide solution with Kw * solution - 12.

Example 3 parts by weight of pulp of the same quality as in Example 1 are basified; the excess amount of sodium hydroxide is differentiated to the degree of compression 3. The resulting alkaline cellulose is ground as in Example 1 and saturated with sulfur dioxide. To the pulp prepared in this way, 0.05 parts by weight of cobalt acetate and 25 parts by weight of urea are added with stirring.

The mixture was homogenized at 40 ° C for 2 hours and then heated at 135 ° C for minutes. The product was purified as in Example 1.

24.5 parts by weight of cellulose carbamate are obtained with the following quality:

Color - light gray-yellow, DP = 319, nitrogen content - 1,6% and excellent solubility in 9% sodium hydroxide solution, with Kw * of the solution being 9.

Example 4 parts by weight of Ketchiken pulp with DP = 649 in leaves are basified as in Example 1 and then compressed to a degree of compression of 2.3. The alkaline cellulose leaves are then ground and the resulting mass is saturated with carbon dioxide gas as in Example 1. To this meat, 0.001 parts by weight of cobalt acetate and 25 parts by weight of urea are added while stirring. The resulting mixture was homogenized at 50 ° C for 2 hours and then heated at 150 ° C for 30 minutes. The product obtained is purified as in Example 1.

25.5 parts by weight of cellulose carbamate are obtained with the following properties:

Bound nitrogen content - 1.5%, DP = 442, very good solubility in 9% sodium hydroxide solution with Kw * solution - 15.

Example 5 parts by weight of pulp as in Example 4 is basified and saturated with carbon dioxide gas as in Example

1. To the meat obtained, 2.5 parts by weight of formic acid and 25 parts by weight of urea are added while stirring. The mixture is homogenized at 82 ° C for 2 hours and then heated at 135 ° C for 90 minutes. The product obtained is purified as in Example 1.

23.5 parts by weight of cellulose carbamate are obtained, having the following characteristics:

Color - gray-yellow, bound nitrogen content - 0,9 X, DP = 430, very good solubility in 9% sodium hydroxide solution with Kw * solution - 25.

Example 6

23.5 pbw of pulp as in Example 1 is basified and compressed to a degree of compression of 2.3. The resulting alkaline cellulose is ground for 1 hour and then 1.5 parts by weight of formic acid, 0.01 parts by weight of cobalt acetate (II) and 25 parts by weight of urea are added with stirring.

The mixture was homogenized for 1 hour, then neutralized for 90 minutes with carbon dioxide gas and for 90 minutes, heated to 160 ^e C. This product is purified as in example first

23.5 parts by weight of cellulose carbamate are obtained, having the following characteristics:

Color - gray-yellow, bound nitrogen content - 1.9%, DP = 252, very good solubility in 9-l sodium hydroxide solution with Kw * solution - 30.

Example 7

23.5 pbw of pulp as in Example 1 is basified and then compressed to a compression rate of 2.4. The alkaline cellulose obtained is ground in a roll-off roller for 1 hour and then 2.5 parts by weight of acetic acid, 1.5 parts by weight of formic acid, 0.05 parts by weight of cobalt acetate (II) and 25 parts by weight of urea are added. The reaction mixture is homogenized for 2 hours and then neutralized with gaseous carbon dioxide and sulfur dioxide. After neutralization, the mixture was heated at 135 ° C for 90 minutes. The product obtained is purified as in Example 1.

24 parts by weight of cellulose carbamate are obtained having the following characteristics:

Color - gray-yellow, bound nitrogen content - 2.2%, DP = 264, very good solubility in 9 36-day sodium hydroxide solution with Kw-solution -18.

Example 8 parts by weight of leaf pulp and having the properties as in the example are basified in a mercerization press for 1 hour with 18% sodium hydroxide.

The resulting alkaline cellulose is pressed to the degree of compression

2.9. The compressed leaves decanted twice with water, kept for 1 h at 20 ^e C and re-compressed. The washed leaves were washed with an aqueous solution containing 40% urea and 0.01% cobalt acetate (II) and then saturated with gaseous carbon dioxide for 1 hour. The mass is compressed to a compression factor of 1.9 after draining the excess solution. The leaves are then dried and heated at 135 ° C for 120 minutes. The product obtained is purified as in Example 1.

98 parts by weight of leaf-like cellulose carbamate are obtained with the following characteristics:

Color - light gray-yellow, bound nitrogen content - 2,4%, DP = 258, very good solubility in 9% sodium hydroxide solution with Kw * solution - 14.

Example 9

23.5 pbw of Modo Crown pulp having the properties of Example 1 are saturated in a mercerization press for 1 hour at 25 ° C with an aqueous solution containing 200 pbw of urea, 2 pbw of sodium carbonate and 2 pbw of sodium sulfate. The excess amount of the solution is then removed by compression to a compression factor of 3.2. The pressed leaves are air dried and then heated at 140 ° C for 2 hours. The product obtained is purified as in Example 1.

26 parts by weight of cellulose carbamate in leaves are obtained. Product characteristics are as follows:

Color - straw-yellow, bound nitrogen content - 1,4%, DP = 589, good solubility in 9% sodium hydroxide solution with Kw * solution value - 48.

Example 10 parts by weight of Modo Crown pulp having the properties as in Example 1 is basified as in Example 8 and washed in the form of petals. The leaves are then saturated at 30 ° C for 60 minutes with 500 parts by weight of a solution containing 200 parts by weight of urea and 10 parts by weight of acetic acid. The leaves are air dried after pressing the excess solution to a compression factor of 2.0 and then heated at 135 ° C for 90 minutes. The product obtained is purified as in Example 1.

100 parts by weight of cellulose carbamate are obtained. Product characteristics are as follows:

Color - light straw-yellow, bound nitrogen content - 2.2%, DP = 360, very good solubility in 9% sodium hydroxide solution, Kw * solution value - 20.

Example 11 parts by weight of Modo Crown pulp, having the properties of Example 1, is basified and washed with water as in Example 8. The alkaline reaction cellulose obtained is saturated in a mercerization press for 1 hour at 35 ° C with 500 parts by weight of an aqueous solution. comprising 200 parts by weight of urea and 5 parts by weight of cobalt acetate (II); carbon monoxide is simultaneously blown through the solution. After removing the excess solution, the leaves are pressed to a compression factor of 1.95, then air dried and heated at 135 ° C for 90 minutes.

98.5 parts by weight of cellulose carbamate in leaves are obtained. Product characteristics are as follows:

Color - light straw yellow, bound nitrogen content - 18 DP = 320, very good solubility in sodium hydroxide solution with Kw * solution value - 30.

Claims (4)

Method for producing cellulose carbamate by reacting optionally degraded cellulose with urea or its salts at 130 ° C to 170 ° C, characterized in that the pulp, especially in the leaves, preferably with an alkaline reaction, is treated with urea and / or its salts in in the presence of a synergistic, activating system consisting of gaseous anhydrides of organic and / or inorganic acids and salts of organic and / or inorganic acids, the amount of pulp salts used being from 0.001 to 10 wt. and the weight ratio of pulp to urea and / or salts thereof is maintained in the range of 1: 0.1 to 1: 3, and that the pulp is then heated at 130 to 170 ° C for 10 to 600 minutes, and that the cellulose carbamate obtained is eventually cleans. Process according to claim 1, characterized in that carbon dioxide, sulfur dioxide, carbon monoxide or acetic anhydride are used as gaseous acid anhydrides and sodium acetate, sodium formate, urea formate, urea acetate, cobalt acetate (s) are used as salts. II), cobalt formate (II), sodium carbonate or sodium sulfate. Method according to claim 1, characterized in that the components of the synergistic activating system are added to the pulp alone or together with the urea or its salts by admixing or saturating for 1 to 600 minutes at 20 to 60 ° C. Method according to claim 1, characterized in that the synergistic, activating salt-forming system is formed in the alkaline reaction pulp by neutralizing it with organic and / or inorganic acids such as acetic acid, formic acid and / or acid anhydrides such as carbon dioxide or sulfur dioxide, which are added to the pulp by mixing or saturating for 1 to 600 minutes at 20 to 60 ° C.