SU1419988A1 - Method of producing cellulose diacetate - Google Patents

Description

(21) 4016509 / 23-05

(22) 12.02.86

(46) 08/30/88. Vksh. Number 32

(71) Research Institute of Chemistry, Saratov State University N.G. Chernyshevsky

(72) N.A.Fedova, Z.B.Komarova, A.A. Fedorchenko and E.V.Pichugin (53) 667.464 (088.8)

(56) Akim A.E., Perepechkin L.P. Acetylation pulp, cellulose acetates and acetate fibers. M .: Lesna industry, 1972.

Kostrov Yu.K. Chemistry and technology of acetate fiber. M .: Himi, 1967, 41-42.

(54) METHOD FOR OBTAINING CELLULOSE DIACETATE

(57) The invention relates to the chemical fiber industry and plastics industry and can be used to make acetate fiber. The invention makes it possible to reduce the content of low molecular weight fractions in the target product to 1.5–3.5%, reduce the viscosity of 23% solutions to 250–400 s and increase their filterability to 16–20 g / cm by obtaining diacerides. tat homogeneous acetic acid method, including activation of cellulose, acetylation and saponification at 52–57 s, until the content of bound acetic acid in the target product is 56.5–57.5%. followed by precipitation, washing and drying the target product. 1 tab.

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The invention relates to the chemical fiber industry and plastic mass and can be used to make acetate fiber. I The purpose of the invention is to reduce the content of:: Cani low molecular weight fractions in the target product, to reduce the viscosity of ITS concentrated solutions and to increase their filterability.

Example 1 (known method). Activation of cellulose.

26 g of cellulose are loaded into the activator, then 90-95% acetic acid is fed in an amount necessary to create a 2.5% suspension of cellulose in acetic acid. The temperature of the suspension does not exceed 25 -. The duration of the process is 22-30 minutes.

After the activation, the displacement of water from cellulose is carried out with glacial acetic acid, after which the cellulose is squeezed to a dry residue of 45-58% and fed to the acetyl torus. Cellulose Acetylation

one

The acetylating mixture consists of

acetic anhydride (20% more than the theoretical consumption for the acetylation of cellulose and water binding), the catalyst — sulfuric acid (3.5% by weight of cellulose) and the solvent — acetic acid (300% by weight of cellulose). The modulus of the bath is 7. The duration of acetylation is 20 minutes, then the absorption takes place.

Omymashenie cellulose triacetate.

The mixture consists of acetic acid and water in the ratio of 60:40. The content of water in the syrup with gum should not exceed 10-15%. The content of sulfuric acid in relation to the cellulose is 0.34% by weight of the total syrup. The saponification temperature is 59 ° C.

Deposition.

Adetilcellulose is planted in a 30% solution of acetic acid at a precipitation bath temperature of 35 ° C for 20 minutes.

Rinsing, drying.

Washing planted cellulose are water with a counter-flow method until neutral reaction by washing with water. Washing time is 25-30 minutes. The cellulose is pressed to a moisture content of 60% by weight, and dried at 120 ° C to a moisture content of cellulose equal to 35% by weight -%.

Example 2. Cellulose acetate containing 56.51% bound acetic acid, with a mol weight of 80,000, was obtained as in Example 1, but saponification was carried out at. Cellulose acetate characterizes the viscosity if the intruability of the concentrated solution. The viscosity of the solution is 400 s, which

o 3.7 times lower viscosity of solution from cellulose acetate, obtained by lime process. The filterability is 16 g / cm, which is 3.2. times the filterability of the solution of acetated cellulose obtained in a known manner.

Example 3. Cellulose acetate containing 57.1% of bound acetic acid, mol. weighing 80900 is prepared as in example 1, but at the temperature of ginger. The viscosity of the solution is 300 s, which is 5 times lower than the viscosity of a solution of cellulose acetate obtained in a known manner,

5 a. The filterability is 18 g / cm, which is 3.6 times the filterability of the cellulose acetate solution obtained in a known manner.

Example 4 Cellulose Acetate

0 containing 57.51% of bound acetic acid, mol. weighing 10,800 is prepared according to Example 1, but at a melting temperature of 52 ° C. The viscosity of a 23% solution is 250 seconds, which is 6 times lower than the viscosity of a solution of cellulose acetate prepared in a known manner. which is 4 times higher filterability pact-thief cellulose acetate, obtained

0 in a known way.

Example 5. Cellulose acetate containing 57.95% of bound acetic acid, mol. weight 108300 was prepared according to example 1, but at a saponification temperature of 50 ° C. Viscosity is 23%

five

0

five

the solution is 400 s, which is 3.75 times lower than the viscosity of the cellulose acetate solution obtained in a known manner. The filterability of the solution is 18 g / cm, which is 3.6 times higher than the filterability of the cellulose acetate solution obtained in a known manner, but 1.1 times lower than the filterability of the cellulose acetate solution obtained in Example 4.

The properties of cellulose acetates obtained in winners 1-5 are presented in the table.

Claims (1)

Invention Formula A method of producing cellulose diacetate by a homogeneous acetic acid method, including cellulose activation, acetylation, saponification, precipitation, washing and drying of the target product, characterized in that. Editor N.Kishtulinets Compiled by T. Martinska Tehred A. Kravchuk Proofreader A.T. Order 4287/23 Circulation 434 VNIIPI USSR State Committee .on matters of inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 In order to reduce the content of low molecular weight fractions in the target product, reduce the viscosity of its concentrated solutions and increase their filterability, saponification is carried out at 52-57 ° C to contain 56.5-57.5% bound acetic acid in the target product. Subscription