阅读说明：本技术 一种低温水洗聚乙烯醇纤维的装置及其方法 (device and method for washing polyvinyl alcohol fibers at low temperature ) 是由 鲁建国 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种低温水洗聚乙烯醇纤维的装置及其方法,装置包括：电解池,设置于电解池两侧的正电极板,负电极板,聚乙烯醇纤维穿过正电极板、负电极板之间的位置,设置于电解池两侧的反应废料出口,设置于所述电解池上端的出气口；本发明通过将水洗池设置成电解池,将聚乙烯醇纤维的残留物经过电解反应、水解反应由出气口和反应废料出口排出,对温度要求低,使得聚乙烯醇纤维生产转化率高。(The invention discloses a device and a method for washing polyvinyl alcohol fibers at low temperature, wherein the device comprises: the device comprises an electrolytic cell, positive electrode plates and negative electrode plates, wherein the positive electrode plates and the negative electrode plates are arranged on two sides of the electrolytic cell, polyvinyl alcohol fibers penetrate through positions between the positive electrode plates and the negative electrode plates, reaction waste outlets are arranged on two sides of the electrolytic cell, and an air outlet is arranged at the upper end of the electrolytic cell; according to the invention, the water washing tank is set as the electrolytic tank, and the residues of the polyvinyl alcohol fibers are discharged from the gas outlet and the reaction waste outlet through the electrolytic reaction and the hydrolysis reaction, so that the requirement on temperature is low, and the production conversion rate of the polyvinyl alcohol fibers is high.)

1. An apparatus for low temperature water washing of polyvinyl alcohol fibers, comprising: the electrolytic cell comprises an electrolytic cell, positive electrode plates and negative electrode plates, wherein the positive electrode plates and the negative electrode plates are arranged on two sides of the electrolytic cell, polyvinyl alcohol fibers penetrate through positions between the positive electrode plates and the negative electrode plates, reaction waste outlets are arranged on two sides of the electrolytic cell, and an air outlet is arranged at the upper end of the electrolytic cell.

2. The apparatus of claim 1, further comprising: and the polyvinyl alcohol fiber conveying assembly is arranged between the positive electrode plate and the negative electrode plate.

3. the apparatus of claim 2, wherein the polyvinyl alcohol fiber conveying assembly comprises: squeeze rollers arranged at the front and rear positions of the upper end of the electrolytic cell, and guide rollers arranged in the electrolytic cell and positioned between the positive electrode plate and the negative electrode plate.

4. The apparatus for low temperature water washing of polyvinyl alcohol fiber according to claim 3, wherein there are two guide rollers.

5. the apparatus for washing polyvinyl alcohol fiber with water at low temperature according to claim 1, wherein an inclined slope is provided between the reaction waste outlet and the polyvinyl alcohol fiber.

6. the apparatus for low-temperature water washing of polyvinyl alcohol fibers according to claim 5, wherein the inclined slope is inclined at an angle of 45 °.

7. A method for washing polyvinyl alcohol fiber at low temperature is characterized by comprising the following steps:

An air outlet is arranged on the electrolytic cell, and reaction waste outlets are arranged on two sides of the lower end of the electrolytic cell;

Injecting water with the temperature range of 40-55 ℃ from a water injection port of the electrolytic cell, then enabling the polyvinyl alcohol fiber to pass through a space between the positive electrode plate and the negative electrode plate, opening the electrolytic cell, and introducing direct current, wherein the direct current voltage range is 1.23-300V;

The reaction waste flows out from a reaction waste outlet, and the washed polyvinyl alcohol fiber is dried; the reaction waste comprises: sodium sulfate, sodium acetate, sodium hydroxide, acetic acid, sulfuric acid.

8. The method of claim 7, wherein the DC voltage is in the range of 15-25V.

Technical Field

The invention relates to the field of polyvinyl alcohol fiber production processes, in particular to a device and a method for washing polyvinyl alcohol fibers at low temperature.

background

The coagulating bath for wet spinning of polyvinyl alcohol includes inorganic salt aqueous solution, NaOH aqueous solution and organic solvent, and Na is most widely used₂SO₄An aqueous solution.

In the production process of polyvinyl alcohol, byproducts are difficult to completely remove, most commonly CH₃COONa remains.

The post-processing of the polyvinyl alcohol fibers generally comprises the procedures of stretching, heat setting, water washing, oiling, drying and the like. The washing temperature is 70-80 ℃, because the washing can effectively remove CH attached to the fiber at the temperature₃COONa and CH₃COONa is washed away, and the normal temperature water is washed with CH₃COONa and CH₃COONa causes poor solubility, resulting in CH attached to the fiber₃COONa and CH₃COONa is not easy to be washed off, and the washing effect is not good. The water washing with normal temperature water needs to increase the washing time and the washing water amount, thereby wasting a large amount of water resources.

In the process of producing polyvinyl alcohol fibers by wet spinning, the temperature corresponding to a semi-finished product when the semi-finished product generates a certain shrinkage rate in hot water is measured, and the method is called an in-water softening point measurement method and is also called an RP value. When the RP value is lower than 70 ℃, part of the structure of the polyvinyl alcohol fiber begins to dissolve into water during water washing, so that the yield is reduced; when the RP value is less than 65 ℃, the amount of the polyvinyl alcohol fiber partial structure dissolved in water increases, and the production is difficult.

Therefore, the washing temperature and the RP value of the polyvinyl alcohol fiber have close relationship. When the RP value is low, the washing temperature of the polyvinyl alcohol fiber is also reduced, the washing effect is poor, the washing water consumption is high, and the yield of the polyvinyl alcohol fiber is low; when the RP value is high, the washing temperature of the polyvinyl alcohol fiber can be increased, the washing effect is good, the water consumption for washing is low, and the yield of the polyvinyl alcohol fiber is high.

the market needs a water washing device which has low temperature requirement and improves the production conversion rate of polyvinyl alcohol fibers, and the invention solves the problems.

disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a device and a method for washing polyvinyl alcohol fibers with low-temperature water.

In order to achieve the above object, the present invention adopts the following technical solutions:

An apparatus for low temperature water washing of polyvinyl alcohol fibers comprising: the electrolytic cell, set up positive electrode plate, the negative electrode plate in electrolytic cell both sides, polyvinyl alcohol fibre passes the position between positive electrode plate, the negative electrode plate, set up the reaction waste material export in electrolytic cell both sides, set up the gas outlet in electrolytic cell upper end.

the device for washing the polyvinyl alcohol fiber at low temperature further comprises: and the polyvinyl alcohol fiber conveying assembly is arranged between the positive electrode plate and the negative electrode plate.

The device for washing the polyvinyl alcohol fiber at low temperature comprises a polyvinyl alcohol fiber conveying assembly: squeeze rollers arranged at the front and rear positions of the upper end of the electrolytic cell, and guide rollers arranged in the electrolytic cell and positioned between the positive electrode plate and the negative electrode plate.

In the device for washing the polyvinyl alcohol fiber at low temperature, two guide rollers are provided.

In the device for washing the polyvinyl alcohol fibers at the low temperature, the inclined slope is arranged between the reaction waste outlet and the polyvinyl alcohol fibers.

In the device for washing the polyvinyl alcohol fiber at the low temperature, the inclination angle of the inclined slope is 45 °

A method for washing polyvinyl alcohol fiber at low temperature is characterized by comprising the following steps:

An air outlet is arranged on the electrolytic cell, and reaction waste outlets are arranged on two sides of the lower end of the electrolytic cell;

Injecting water with the temperature range of 40-55 ℃ from a water injection port of the electrolytic cell, then enabling the polyvinyl alcohol fiber to pass through a space between the positive electrode plate and the negative electrode plate, opening the electrolytic cell, and introducing direct current, wherein the direct current voltage range is 1.23-300V;

The reaction waste flows out from a reaction waste outlet, and the washed polyvinyl alcohol fiber is dried; the reaction waste comprises: sodium sulfate, sodium acetate, sodium hydroxide, acetic acid, sulfuric acid.

in the method for washing the polyvinyl alcohol fiber at low temperature, the direct current voltage range is 15-25V.

The invention has the advantages that:

the invention promotes the electrolysis of sodium acetate and sodium sulfate by introducing direct current; discharging electrolysis products of the sodium hydroxide, the sodium acetate and the sodium sulfate and sulfuric acid by utilizing the characteristic that the density of the sodium hydroxide, the sodium acetate, the sodium sulfate and the sulfuric acid is increased along with the reduction of the temperature and utilizing the inclination of a washing tank; thereby improving the conversion rate of the polyvinyl alcohol fiber production; the washing temperature of the polyvinyl alcohol fiber is reduced, and energy is saved;

The washing effect of sodium sulfate and sodium acetate in the production process of polyvinyl alcohol fibers is improved, and the residues of the sodium sulfate and the sodium acetate in the polyvinyl alcohol fibers are reduced;

The continuous production reduces the water consumption, and greatly reduces the water consumption of the washing procedure of the polyvinyl alcohol fiber.

Drawings

FIG. 1 is a cross-section of one embodiment of the present invention;

Fig. 2 is a longitudinal section of an embodiment of the invention.

The meaning of the reference symbols in the figures:

The device comprises an electrolytic cell 1, a positive electrode plate 2, a negative electrode plate 3, an air outlet 4, a squeezing roller 5, a guide roller 6, polyvinyl alcohol fibers 7, a reaction waste outlet 8, an inclined slope 9 and a water injection port 10.

Detailed Description

the invention is described in detail below with reference to the figures and the embodiments.

An apparatus for low temperature water washing of polyvinyl alcohol fibers comprising: the electrolytic cell comprises an electrolytic cell 1, positive electrode plates 2 and negative electrode plates 3 which are arranged on two sides of the electrolytic cell 1, polyvinyl alcohol fibers 7 which penetrate through the positions between the positive electrode plates 2 and the negative electrode plates 3, reaction waste outlets 8 which are arranged on two sides of the electrolytic cell 1, an air outlet 4 which is arranged at the upper end of the electrolytic cell 1, and a polyvinyl alcohol fiber conveying assembly which is arranged between the positive electrode plates 2 and the negative electrode plates 3.

The polyvinyl alcohol fiber conveying component comprises: squeeze rollers 5 provided at front and rear positions of the upper end of the electrolytic cell 1, and guide rollers 6 provided in the electrolytic cell 1 and located between the positive electrode plate 2 and the negative electrode plate 3. As shown in fig. 1, there are two guide rollers 6.

polyvinyl alcohol fibers 7 pass through the squeezing roller 5 and the guide roller 6, are led by the guide roller 6 to pass through between the positive electrode plate 3 and the negative electrode plate 3, and react, sodium acetate and sodium sulfate are respectively changed into sodium sulfate, sodium acetate and sodium hydroxide which flow out from a reaction waste outlet 8 close to the negative electrode plate 3, and the sodium sulfate, the sodium acetate, the acetic acid and the sulfuric acidHydrogen and CH from the reaction waste outlet 8 near the positive electrode plate 2₃CH₃Oxygen and CH are discharged from gas outlet 4 near negative electrode plate 3₃CH₃is discharged from the gas outlet 4 close to the positive electrode plate 2; the cleaned polyvinyl alcohol fibers 7 are extruded out of the pool from the extrusion roller 5.

Ionization and electrolysis of sodium acetate

1. Ionization of sodium acetate

CH₃COONa＝CH₃COO^-+Na⁺

2. electrolysis of sodium acetate

3. Hydrolysis of sodium acetate

CH₃COO^-+H₂O＝CH₃COOH+OH^-

4. Electrolysis of sodium acetate

II, ionization and electrolysis of sodium sulfate:

1、Na₂SO₄ionization of aqueous solutions

Na₂SO₄＝2Na⁺+SO₄ ^2-

H₂O reversible symbol H⁺+OH^-

2. Electrolysis of sodium sulphate

Cathode: 4H⁺+4e^-→2H²↑

Anode: 4OH^-→2H₂O+O²↑+4e^-

In order to facilitate the reaction waste to leave the electrolytic cell 1 quickly, an inclined slope 9 is arranged between the reaction waste outlet 8 and the polyvinyl alcohol fiber; preferably, the inclination angle of the inclined slope 9 is 45 °

A method for washing polyvinyl alcohol fiber at low temperature comprises the following steps:

An air outlet 4 is arranged on the electrolytic cell 1, and reaction waste outlets 8 are arranged on two sides of the lower end of the electrolytic cell 1;

Injecting water with the temperature range of 40-55 ℃ from a water injection port 10 of the electrolytic cell 1, then enabling the polyvinyl alcohol fiber to pass through the space between the positive electrode plate 2 and the negative electrode plate 3, opening the electrolytic cell 1, and introducing direct current, wherein the direct current voltage range is 1.23-300V;

Preferably, the DC voltage is in the range of 15-25 volts.

The reaction waste flows out from a reaction waste outlet 8, and the washed polyvinyl alcohol fiber is dried; the reaction waste material from the vicinity of the positive plate includes: sodium sulfate, sodium acetate, sodium hydroxide, acetic acid, sulfuric acid.

The device and the method can improve the production conversion rate of the polyvinyl alcohol fiber below delta by experimental verification;

Testing of sodium acetate content

1 range

Sodium acetate content is determined by chemical titration or conductivity. Additives interfere and therefore, these methods are not suitable for polyvinyl alcohol materials containing additives.

Principle 2

2.1 titration method

the sample is dissolved in water, a mixed solution of methylene blue and dimethyl yellow is used as an indicator, hydrochloric acid is used for titration, and then the content of sodium acetate is calculated.

3 titration method

3.1 reagents

3.1.1 hydrochloric acid standard titration solution: c (hcl) o.1mol/L.

3.1.2 Methyleneblue-dodecamethylyellow mixed indicator: 1:1.

note: both the methylene blue and the dimethyl yellow are 0.1% ethanol solutions.

3.2 instruments

3.2.1 Erlenmeyer flask: 500mL with a stopper.

3.2.2 graduated cylinder: 200mL, the index value is 2 mL.

3.2.3 burette: 50mL, the index value is 0.1 mL.

3.3 operating procedure

3.3.1 weighing about 5g of sample, and accurately obtaining 0.001g of sample; put into an Erlenmeyer flask, add 200mL of water, and heat to dissolve.

3.3.2 after the sample is dissolved, cooling, adding 15-20 drops of mixed indicator of methylene blue and dimethyl yellow, and then titrating with 0.1mol/L hydrochloric acid standard titration solution to the end point. At the end point, the color of the solution changed from green to light purple. And (5) carrying out a blank test.

Note: samples with low alcoholysis may sometimes make the solution cloudy. Once this occurs, the solution is slowly cooled with gentle stirring or the aqueous solution is replaced with a 3:1 water/methanol mixture.

3.3.4 results show

The sodium acetate content is calculated as mass fraction NaAc, the value is expressed in% and is calculated according to the formula:

In the formula:

u 1-number of volumes of standard titration solution of hydrochloric acid consumed by titrating a sample in milliliters (mL);

u 0-number of volumes of standard titration solutions of hydrochloric acid consumed for titration of a blank in milliliters (mL);

C is the accurate value of the concentration of the hydrochloric acid standard titration solution, and the unit is mol per liter (mol/L);

0.08203-the molar mass of sodium acetate divided by 1000 in grams per mole (g/mol);

m is a number of the mass of the sample in grams (g).

The arithmetic mean of the results of the two determinations was calculated and the results were retained up to 2 decimal places.

Note: if sodium hydroxide is present in the sample, attention should be paid to its effect on the determination of sodium acetate content; however, the effect of sodium hydroxide on the determination of sodium acetate content was not taken into account when sodium acetate was used for ash calculation.

5 test report

a) the experimental method in the experimental report is according to GB/T12010.2;

b) The test sample is the polyvinyl alcohol fiber washed by the method of the invention.

c) the measurement result is 0.14%;

d) The results of the individual measurements were 0.14%, 0.13%, 0.15%, and 0.13%.

Determination of sodium sulfate content

subject matter and scope of application

And (4) measuring the content of sodium sulfate in the polyvinyl alcohol fiber.

2 test method

2.1 instrumentation

Beaker (250ml)

Graduated pipette (2ml)

acid burette (5ml)

measuring slip (10ml)

Pipette (25ml)

Measuring cup (10ml)

2.2 use of reagents

(EDTA) ═ 0.1mol/LEDTA solution

pH 10 buffer

Luohai T concentrated hydrochloric acid

BaCl2/MgCl2 mixed liquor

2.3 principle of measurement

Adding excessive mixed solution of barium oxide and magnesium chloride to make sulfate radical produce barium sulfate precipitate, titrating the excessive barium ion with EDTA in the presence of proper amount of magnesium ion, reacting the sulfate radical combined with calcium and magnesium in the solution with barium salt to produce barium sulfate precipitate, and dissociating to obtain ion, with equivalent calcium and magnesium ion being complexed with equivalent EDTA during titration.

2.4 test methods

2 g of polyvinyl alcohol fiber is taken and placed in a 250m beaker, about 150ml of water is added, the mixture is placed on an electric furnace and boiled, 5 drops of concentrated hydrochloric acid are added, the mixture is carefully stirred and 25ml of barium chloride-magnesium chloride mixture is added, then the mixture is kept on the electric furnace for 5 minutes, the mixture is taken down and cooled to room temperature, 10m of pH 10 buffer solution and 4-5 drops of complex black T indicator are added, C (EDTA) -0.1 ml/LEDTA standard solution is added until pure blue color is used as an end point, the consumption ml of C (EDTA) -0.1 mol/LEDTA standard solution is recorded as a, and the consumption ml of C EDTA) -0.1 mol/LEDTA standard solution is recorded as b when a blank test is carried out.

2.5 calculation of

In the formula: 1.449 is NaSO₄：H₂SO₄the ratio of (A) to (B);

1M Na₂SO₄Represents Na₂SO₄Has a molecular weight of 142.06.

3, results:

a) The test sample is the polyvinyl alcohol fiber washed by water by the method;

b) The determination result is 0.0063%;

c) The results of the individual measurements were 0.0063%, 0.006%, 0.0064% and 0.0063%.

Experiments show that the method of the invention can well remove the sodium acetate and the sodium sulfate remained in the polyvinyl alcohol fiber.

the invention promotes the electrolysis of sodium acetate and sodium sulfate by introducing direct current; discharging electrolysis products of the sodium hydroxide, the sodium acetate and the sodium sulfate and sulfuric acid by utilizing the characteristic that the density of the sodium hydroxide, the sodium acetate, the sodium sulfate and the sulfuric acid is increased along with the reduction of the temperature and utilizing the inclination of a washing tank; thereby improving the conversion rate of the polyvinyl alcohol fiber production; the washing temperature of the polyvinyl alcohol fiber is reduced, and energy is saved; the washing effect of sodium sulfate and sodium acetate in the production process of polyvinyl alcohol fibers is improved, and the residues of the sodium sulfate and the sodium acetate in the polyvinyl alcohol fibers are reduced; the continuous production reduces the water consumption, and greatly reduces the water consumption of the washing procedure of the polyvinyl alcohol fiber.

the foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.