SU939447A1 - Process for producing cellulose acetates - Google Patents

Description

() METHOD OF OBTAINING ACETATE CERTAINS

one

The invention relates to the production of highly heat-resistant acetate materials used to form films, fibers and plastics.

A known method for producing thermostable cellulose acetates (AC), where compounds of various classes, in particular secondary aromatic amines — neozon-D 1, are used as thermal stabilizers.

However, these antioxidants thermostabilizers are not resistant to the action of various organic solvents and do not allow producing AC with high heat resistance during operation.

Closest to the proposed method of obtaining stable ACs, which consists in acetylating activated cellulose with acetic anhydride in a homogeneous medium in the presence of a catalyst, introducing a heat stabilizer into the resulting syrup and planting the desired product i

where an aqueous solution of metal salts, for example calcium chloride (HC) 2, is used as a heat stabilizer.

However, the known method does not allow obtaining products stable to high temperatures. The additive salt used is not soluble in organic solvents for the AC and UJ is not sensitive to the sulfonic ester removal reaction, therefore additional washing of calcium oxide is required.

The purpose of the invention is to increase the yopestability of cellulose acetate

15 and simplification of technology (exclusion of an additional stabilization stage), reduction of consumption of stabilizing additives, expansion of the raw material base 20 and the use of available additives.

The goal is achieved by the fact that in the method of producing AC by acetylation of activated cellulose with acetic anhydride in homogeneous

the medium in the presence of a catalyst, the introduction of a stabilizer into the resulting syrup and the precipitation of the target product, use the tropeolin of the general formula as a thermal stabilizer

Y

-XO) -N NH

where at

X,, RryQVsOgNd T-oj

at

R-.H / O.NH-et-00;

in the amount of 0.1-1.0% by weight of the celine vines.

The processing method is simple and the starting reagents are easily accessible. With this treatment, the resulting AC have high thermal stabilizing properties.

Example 1.10 g of cellulose is activated with 50 ml of acetic acid. The activated cellulose is then acetylized with a mixture of 30 ml of acetic anhydride and 0.1 g of sulfuric acid. Acetylation is carried out at 8-kO C with constant stirring. When homogeneous homogeneity is achieved, the syrup is diluted at room temperature with a mixture of 30 ml of methylene chloride, 70 ml of acetic acid and 0.01 g (0.1%) of T-0. Before being introduced into the mixture, T-0 is dissolved in ethyl alcohol or formic acid. When homogeneity is achieved, the solution is planted in hot water (.70-80 ° C.) The precipitated product is washed with distilled water until neutral, dried at 48-50 ° C to a constant weight and subjected to testing.

Properties of the obtained AC are given in table. one.

Example 2: AC is prepared analogously to Example 1. At a dilution, 0.05 g (0.5%) of T-0 is introduced.

Example 3. AC is prepared analogously to Example 1, but 0.1 g of (G) T-0 is introduced.

For comparison, table. 1 shows 0 data on the effect of the number of known and proposed additives on the AC destruction process.

From the obtained data table. Figure 1 shows that with an increase in the amount of 5 introduced T-0 (up to 1%), the thermal stability of the active center increases and exceeds the thermal stability of the samples with the addition of HC, which is confirmed both by maintaining the specific viscosity and by slowing down the rate of color change and weight loss.

In tab. Table 2 shows the comparative data for various tropeolines taken in an amount of 0.5% by weight of cellulose. 5 The heat stabilizing properties of the obtained ACs are evaluated by color change (GOST 12808-67) and weight loss, as well as by maintaining the specific viscosity when heated in air at 0 210 ° C for 90 minutes. Specific

The viscosity (0.5% AC) is determined in a mixture of methylene chloride and alcohol in the ratio 9: 1i with a DG-29 type viscometer with a capillary diameter of 0.73 mm. The weight loss of the obtained ACs is determined using a torsion balance with an initial weight of 0, g (heating rate, V C / min), when heated in air to 286 ° C.

0 The proposed method for the preparation of stable AC allows the use of readily available indicators of tropeolins as stabilizing agents, reduces the consumption of stabilized DI additives and simplifies the technology by eliminating the additional stage of stabilization of AC,

The economic efficiency of the use of such additives is due to

0 their higher thermal stabilization efficiency compared to known methods.

Table 1

table 2

Claims (2)

Claim 1. A method of producing cellulose acetate 40 acetylated cellulose by acetylation of acetic anhydride in a homogeneous medium in the presence of a catalyst, introducing a thermal stabilizer into the resulting syrup and planting the target product, characterized in that, in order to increase the thermal stability of the target product and simplify the technology, as a thermal stabilizer, 50 tropeolin of the general formula are used When Y ⁿ Xxso ^ Na, Y = H in an amount of 0.1-1.0% by weight of cellulose. 2. The method according to claim 1, characterized in that the thermostabilizer is administered at 20-25 ° C.