SU550408A1 - Composition based on viscose to produce semi-permeable films - Google Patents

Description

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This invention relates to semipermeable polymeric films that can be used for medical purposes, in particular for artificial kidney devices (LIP), as well as in other fields of technology, for example in the chemical industry.

A known composition for producing semipermeable films based on cellophane, obtained from a solution of viscose, containing 8.5-9.0% a-cellulose and 5.5-6.0% sodium hydroxide 1.

The disadvantage of the composition is the low strength of the foils and insufficient permeability to low molecular weight compounds.

Also known is a polymer semipermeable film based on cellophane, modified by the introduction of polymer additives into a solution of viscose, for which sodium styrene sulfonate homopolymer is used, which has the following composition, wt. %: sh-Cellulose8,5

Sodium hydroxide 6.0

Sodium sulfonate homopolymer 60 (by weight of cellulose) 2.

The main disadvantage of these polymeric semi-permeable films is their relatively low permeability to low molecular weight substances, for example

measures urea creatinine. This leads to the necessity of using, for example, dialysis devices with a large surface area of a nylon-permeable membrane (1.0-1.2 m) in an artificial kidney apparatus.

The mechanical tensile strength of such membranes is at a level of 50-70 kg / cm, which is the minimum margin of safety when used in dialyzatopax.

In order to improve the physicomechanical properties and permeability of films with respect to urea and creatinine, a composition based on viscose is proposed to produce semipermeable films containing a-cellulose, sodium hydroxide, water, and as a modifying agent a copolymer of styrene sulfonate sodium with vinyl acetate molecular weight 300000-400000 when the content of vinyl acetate in the copolymer is 25-30% with the following ratio of components, weight. %:

a-Cellulose8,5-9,0

Sodium hydroxide 5.5-6.0

Modifying additive 1.7-5.1

Water the rest.

In the preparation of polymeric semipermeable films, a copolymer of sodium styrene sulfonate with vinyl acetate is used. The intrinsic viscosity of the copolymer is

in the range of 0.9-1.1, which according to calculated data corresponds to a molecular weight of 300-400 thousand hours. The content of vinyl acetate in the solvent is in the range of 25-30 weight. %, which is the best option, since the use of a copolymer containing not less than 25 wt. % of vinyl acetate leads to a decrease in the strength of the sticks (with the same content of copolymer in the viscose solution), and with an increase in the content of vinyl acetate in the copolymer to 40 weight. % leads to a decrease in the values of permeability coefficients for urea and creatine.

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The table shows the physico-chemical properties of the spikes obtained by the proposed method compared with the known method. The proposed quantitative composition of polymeric semi-permeable films is the best option, since the content of sodium styrene sulfate with vipylacetate copolymer is lower than 20 wt. permeability coefficients are reduced, and with a content of more than 60 weight. h comes the incompatibility of the copolymer with a-cellulose.

Example 1. 14 g of sodium styrene sulfonate copolymer with vinyl acetate, which is 20 wt. hours from a-cellulose, or 1.7 weight. hours per 100 weight. including a solution of viscose, pre-crushed and dissolved in a minimum amount (50-80 ml) of 6% sodium hydroxide solution, is introduced into 800 g of viscose containing 8.5 wt. including a-cellulose and the remaining amount, 6% sodium hydroxide solution. The composition of the copolymer, wt. b .: sodium polystyrenesulfonate 75; vinyl acetate 25. Mol. weight 300 thousand

The solution is mixed well and degassed, and then membranes are molded from it through a wet two-bathing method for the preparation of hydrate-cellulose membranes.

The composition of the bath was Na2SO4 and (NH4) 2SO4, taken in a 1: 1 ratio, concentration 225 g / l.

Composition II bath: H2SO4, a concentration of 80 g / l.

Bath temperature is 25 ° C.

After the baths, the membranes are washed in a stream of cold water, and then they live. From a given volume of solution of viscose and copolymer, 10–15 pieces of membranes 250 × 350 mm in size are obtained.

The permeability of the membrane in urea, measured in a stationary cell of 0.5-10-,

on creatinine - 0,22-10.

Example 2. 28 g of sodium styrene sulfonate copolymer with vinyl acetate, which is 40 wt. hours from a-cellulose or 3.4 wt. hours per 100 weight. including a solution of viscose, pre-crushed and dissolved in a minimum amount (100-120 ml) of 6% sodium hydroxide solution, is introduced into 800 g of viscose containing 8.5 wt. including a-cellulose and the remaining amount - 6% solution

sodium hydroxide. Membranes are prepared from the solution according to the method described above. The permeability of membranes, cm Vc: in urea 0.7-10

creatinine 0.36-10

Example 3. 41 g of sodium styrene sulfonate copolymer with vinyl acetate, which is 60 wt. hours from a-cellulose or 5.1 wt. hours per 100 weight. including viscose solution, is introduced into 800 g viscose, pre-ground and

Claims (2)

dissolved in 150-200 ml of a 6% solution of sodium hydroxide, is introduced into 800 g of viscose containing 8.5 wt. including a-cellulose and the remaining amount, 6% sodium hydroxide solution. The membranes are prepared from the solution according to the method described above. Permeability of the membranes, in urea1,2-10PO to creatinine 0.45-10 , obtained on the basis of a known composition. The technology for producing polymer membranes of the proposed composition does not change as compared with the used membranes of known composition. Claims of the invention Composition based on viscose for producing semi-permeable films, containing a-cellulose, sodium hydroxide, water and a modifying polymer additive, distinguishing —20 5 10 15 u and so that urea and creatinine, the composition contains sodium styrene sulfonate-vinyl acetate copolymer with a molecular weight of 300,000-4,000,000 as the modifying additive, while the content of vinyl acetate in the copolymer is 25-30% with the following ratio of components, %: a-Cellulose 8.5-9.0 Sodium hydroxide 5.5-6.0 Modifying additive 1.7-5.1 Water Water Else. Sources of information taken into account in the examination 1. US Patent No. 3593855, cl. 210-22, 1971. 2. USSR author's certificate No. 450824, cl. From 08L 1/24, 1975.