CN113150334A

CN113150334A - Preparation process of nitrocellulose membrane

Info

Publication number: CN113150334A
Application number: CN202110197778.6A
Authority: CN
Inventors: 宋亚琳; 陈立梅
Original assignee: Shenzhen Connecticut Biotechnology Co ltd
Current assignee: Shenzhen Connecticut Biotechnology Co ltd
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-07-23
Anticipated expiration: 2041-02-22
Also published as: CN113150334B

Abstract

The application relates to the technical field of preparation of nitrocellulose membranes, and discloses a preparation process of a nitrocellulose membrane, which comprises the following steps: (1) preparing a nitrocellulose membrane paddle; (2) filtering the membrane pulp obtained in the step (1); (3) coating and forming the membrane slurry in the step (2), and preparing a nitrocellulose membrane, namely an NC membrane, by adopting a stepped heating mode; (4) surface treatment of an NC film; the NC membrane surface treatment comprises sequentially passing hot water and PBS treatment liquid to treat the NC membrane surface; (5) the NC film was dried. The preparation process can be applied to the production of the NC membrane, can effectively reduce bubbles and impurities generated by the NC membrane, and improves the production quality of the NC membrane.

Description

Preparation process of nitrocellulose membrane

Technical Field

The application relates to the technical field of preparation of nitrocellulose membranes, in particular to a preparation process of a nitrocellulose membrane.

Background

The Nitrocellulose (NC) membrane is a main component of an in vitro diagnostic reagent (immunochromatography), is a carrier of a quality control line C line and a detection line T line, is also a region where an antibody reacts with an antigen, and the quality of the Nitrocellulose (NC) membrane directly influences the performance index of the in vitro diagnostic reagent. Nitrocellulose membranes have been widely used in the fields of biochemistry and molecular biology, particularly in molecular hybridization, immunoblotting, cell culture, and medical diagnostics.

Nitrocellulose membrane is one of the main materials of the new coronavirus (antibody) detection reagents which are well known at present. Due to the global spread of epidemic situations, the antibody reagent is greatly demanded, the demand of the nitrocellulose membrane is increased by one time, and the current market state meets the demand. The index of the enterprises which can produce the nitrocellulose membrane at present can be counted.

The main preparation processes for preparing the nitrocellulose membrane at present comprise: preparing liquid, filtering, coating and forming, adding a surfactant, drying, rolling and cutting.

However, when the nitrocellulose membrane is produced, a large amount of bubbles and impurities exist on the surface of the nitrocellulose membrane, and the nitrocellulose membrane is easy to run, and the quality of the nitrocellulose membrane is affected due to abnormal phenomena such as the inclination of the solution at 45 degrees or the wrapping and wetting of the solution.

Disclosure of Invention

In order to improve the quality of the nitrocellulose membrane, the application provides a preparation process of the nitrocellulose membrane.

The preparation process of the nitrocellulose membrane provided by the application adopts the following technical scheme:

a process for preparing a nitrocellulose membrane, comprising:

(1) preparing a nitrocellulose membrane paddle;

(2) filtering the membrane pulp obtained in the step (1);

(3) coating and forming the membrane slurry in the step (2), and preparing a nitrocellulose membrane, namely an NC membrane, by adopting a stepped heating mode;

(4) surface treatment of an NC film; the NC membrane surface treatment comprises hot water treatment and PBS treatment liquid treatment which are sequentially carried out;

(5) the NC film was dried.

By adopting the technical scheme, the prepared nitrocellulose membrane pulp is filtered, undissolved raw material particles are filtered, the impurity content in the solution of the membrane pulp is reduced, the membrane pulp is coated and formed, the temperature and the humidity in the coating preparation process are controlled, the volatilization speed of a solvent in the membrane pulp is controlled by a stepped heating mode, and the content of bubbles in the coating and forming NC membrane is effectively reduced; removing impurities on the NC film by hot water treatment on the surface of the formed NC film, reducing the generation of bacteria on the surface of the NC film, effectively cleaning and disinfecting the NC film, keeping the uniformity of the quality of the NC film and obtaining the high-quality NC film; and (3) the NC membrane is treated by PBS, so that the physical property of the surface of the NC membrane is improved, the false positive phenomenon is eliminated, and finally, the NC membrane is dried and rolled to finish the production of the NC membrane.

Preferably, the nitrocellulose membrane slurry comprises the following raw materials in parts by volume: 90-110L of solvent, 40-50L of cosolvent, 40-50L of nonsolvent and 5-10L of glycerol;

also comprises nitrocotton, and the weight of the nitrocotton is 22-27 kg.

By adopting the technical scheme, the nitrocotton is completely dissolved in the solvent, impurities on the formed NC membrane are reduced, the cosolvent can be beneficial to dissolving the nitrocotton in the solvent, the glycerol is mainly used as the wetting agent and can increase the hydrophilicity of the surface of the NC membrane, the membrane pulp of the cellulose nitrate is prepared from the raw materials, the raw materials are easy to obtain and produce, and the cost is saved.

Preferably, the solvent comprises any one or more of methyl acetate, ethyl acetate, acetone or butanone; the cosolvent comprises any one or more of methanol and ethanol; the non-solvent includes any one or more of n-butanol and isobutanol.

Preferably, the temperature of the hot water treatment is 60-66 ℃, and the time of the NC membrane after the hot water treatment is more than 1 min.

By adopting the technical scheme, the impurities of the NC membrane can be thoroughly washed away by adding hot water, and the components of the treatment solution required by the surface of the subsequent treatment membrane are protected; the hot water temperature of 60-66 ℃ is helpful for dissolving unreacted substances or impurities attached on the NC membrane, and preventing the NC membrane from being polluted by bacteria generated in the hot water tank; when the temperature is higher than 66 ℃, the hot water is evaporated quickly, which affects the humidity in the air and is energy-consuming.

Preferably, the film paddle adopts a step baking mode in the coating and forming process, the temperature is gradually increased from 19-21 ℃ to 34-36 ℃, and the relative humidity of air is 40% -65%.

By adopting the technical scheme, after the NC film is coated and formed, the volatilization speed of the solvent in the NC film is controlled in a stepped heating mode, the humidity of air is controlled, the content of bubbles in the film paddle is reduced, and the quality of the NC film is improved.

Preferably, in the coating and forming process, the NC film sequentially passes through a constant temperature box with the temperature of 20 +/-1 ℃, 22 +/-1 ℃, 26 +/-2 ℃, 32 +/-1 ℃ and 35 +/-1 ℃.

By adopting the technical scheme, the NC film sequentially passes through the constant temperature boxes at different temperature stages, in the process, the ethanol and the acetone in the film paddle are gradually volatilized, the NC film is gradually solidified into the formed NC film, and the generation of bubbles in the forming process of the NC film is reduced by a step-type heating treatment mode.

Preferably, in the surface treatment process of the PBS treatment liquid, the NC membrane sequentially passes through the first surface treatment groove and the second surface treatment groove, and the pH value of the PBS treatment liquid is 7.0-7.5; when the PBS treatment liquid in the first surface treatment tank is replaced, the PBS treatment liquid is injected into the second surface treatment tank, and then the PBS treatment liquid in the first surface treatment tank is drained.

By adopting the technical scheme, the NC membrane passes through the PBS treatment liquid in the first surface treatment groove or the second surface treatment groove to modify the surface of the NC membrane. In this process, the PBS treatment solution needs to be replaced at intervals, however, the preparation process of the NC membrane is continuous and uninterrupted. When the PBS treatment liquid in the first surface treatment groove (or the second surface treatment groove) is replaced, the PBS treatment liquid is firstly injected into the second surface treatment groove (or the first surface treatment groove), then the PBS treatment liquid in the first surface treatment groove (or the second surface treatment groove) is discharged, the NC film is immersed into the PBS treatment liquid in the second surface treatment groove (or the first surface treatment groove), the NC film is ensured to be treated in the PBS treatment liquid uninterruptedly, the treatment of the replacement of the PBS treatment liquid on the NC film surface is not influenced, the problem that the quality of the NC film is influenced because only one part of the PBS treatment liquid can be replaced by replacing the PBS treatment liquid in a single surface treatment groove is solved, the quality of the NC film is improved, and the production efficiency of the NC film is improved.

Preferably, the membrane paddle after filtration in the step (2) is placed for 2 to 4 days.

By adopting the technical scheme, after the nitrocellulose membrane paddle is filtered, a large amount of bubbles can be generated due to the fluidity of the membrane paddle, and the nitrocellulose membrane paddle needs to be stood for a period of time, so that the bubbles in the membrane paddle escape, and the bubbles in the membrane paddle are reduced.

Preferably, the nitrocellulose membrane slurry is prepared by the following process:

(a) mixing acetone and nitrocotton, stirring uniformly, and dissolving the nitrocotton;

(b) adding ethanol, n-butanol and glycerol, stirring for 2-3 days.

The nitrocellulose membrane is mixed with the acetone by stirring, so that the nitrocellulose is more uniformly mixed with the acetone, and after uniform mixing, ethanol, n-butanol and glycerol are added, wherein the ethanol is used as a cosolvent, so that the nitrocellulose is favorably dissolved in the acetone, the content of solid matters in the nitrocellulose membrane pulp is reduced, the glycerol increases the wettability of the nitrocellulose membrane pulp, and the static electricity on the nitrocellulose membrane is also reduced.

In summary, the present application has the following beneficial effects:

1. the method is added with a hot water treatment step of the surface of the NC membrane, and the NC membrane can effectively wash away impurities on the surface of the NC membrane after being subjected to hot water treatment; if the step of hot water treatment is not adopted, the NC membrane is directly cleaned and treated by the single treatment liquid groove, the concentration of unreacted substances and impurities on the surface of the NC membrane in the PBS treatment liquid is rapidly increased, the original components of the PBS treatment liquid are changed, and the quality of the NC membrane is influenced. In order to ensure the quality of the NC membrane, the NC membrane treated by hot water greatly reduces impurities attached to the NC membrane, reduces impurities in PBS (phosphate buffer solution) treatment liquid, protects PBS treatment liquid components required by the subsequent treatment of the NC membrane surface, and prolongs the time for replacing the PBS treatment liquid.

2. In the application, the temperature of hot water in the hot water treatment process is 63 +/-3 ℃, and the hot water treatment at the temperature is beneficial to dissolving unreacted substances or impurities attached to the NC membrane; meanwhile, the antibacterial effect can be effectively achieved, the NC membrane is prevented from being polluted by bacteria growing on the inner wall of the hot water tank, and the quality of the NC membrane is improved.

3. According to the method for preparing the NC membrane, the NC membrane sequentially passes through the first surface treatment groove and the second surface treatment groove, and PBS treatment liquid in the first surface treatment groove or the second surface treatment groove is intermittently and alternately used, so that the NC membrane can be continuously immersed in the PBS treatment liquid, the replacement of the PBS treatment liquid in the first surface treatment groove or the second surface treatment groove is completed, the treatment effect of the PBS treatment liquid on the NC membrane is not influenced, and the quality and the production continuity of the NC membrane are better guaranteed.

Drawings

FIG. 1 is a flow diagram of a process provided herein;

FIG. 2 is a slip pattern of the NC film surface treatment in the present application;

fig. 3 is a graph showing the effect of capillary migration of NC membranes in example 1 and comparative example 2.

Reference numerals: 1. a hot water tank; 2. a first surface treatment tank; 3. a second surface treatment tank.

Detailed Description

The present application is described in further detail below with reference to figures 1-3.

Nitrocellulose membranes (NC membranes) are one of the most widely used cellulose esters. In the preparation process, the NC membrane can be produced only by the steps of preparation of membrane slurry, filtration, coating, treatment of surfactant, drying and rolling and the like, however, impurities or bubbles are easy to appear on the finished NC membrane in the production process, and the phenomenon that the solution is inclined at 45 degrees or is surrounded and wetted when the NC membrane is used for running a plate is avoided, so that the detection result of the application of the NC membrane is seriously influenced.

Based on this finding, the present applicant has conducted a great deal of experimental research for improving the manufacturing process of nitrocellulose membranes, and as a result, found that impurities or bubbles may be formed during the preparation of the membrane slurry of the NC membrane, filtration, coating molding, surface treatment, and drying, which may affect the quality of the NC membrane.

PBS treatment solution: 81ml of 5mM disodium hydrogenphosphate, 19ml of 5mM sodium dihydrogenphosphate and 0.9g of sodium chloride.

The prepared NC film is inspected in appearance by adopting a lamp inspection mode, and the inspection is mainly performed under a backlight lamp.

Capillary migration test of NC films: adding water into the container, marking one end of the NC film, bonding the marked end of the NC film on the bracket, extending one end of the NC film far away from the mark into the water in the container, and beginning to adsorb the water in the container by the NC film for timing.

Antibody streaking method: and (5) scribing the NC film by using a continuous film spot-on instrument.

And (3) an observation method: when the NC membrane slurry is prepared, a small amount of samples are taken from a sampling port after the mixing is fully carried out to observe the solid state condition, and the membrane slurry preparation is finished if no particulate matters exist; if solid matter exists in the membrane pulp, namely undissolved nitrocotton is contained, the sample is continuously stirred, after stirring for 20-30 minutes, whether the content of the undissolved solid matter is changed or not is observed again, and the membrane pulp is dissolved completely if the content of the undissolved solid matter is not changed.

The hot water used in this application is hot purified water.

Example 1

Referring to fig. 1 and 2, the NC film is prepared as follows:

(1) preparing an NC membrane paddle: weighing 100L of acetone, pouring into a liquid preparation tank, adding 25kg of nitrocotton, starting a stirrer to stir for 3 hours at 65r/min, adding 45L of ethanol, 40L of n-butanol and 5L of glycerol, and continuously stirring for 3 days. Observing the condition of solid matters in the stirred sample to complete the dissolution of the NC membrane paddle;

(2) filtering NC membrane slurry: adopting an oil-proof Polytetrafluoroethylene (PTFE) filtering membrane paddle, and standing for 3 days;

(3) coating and forming by NC film and film slurry: the PE film is tightly attached to the stainless steel, the NC film slurry solution is injected onto the PE film, and the NC film slurry solution runs on the stainless steel belt at a constant speed along with the PE film;

the membrane pulp solution of the NC membrane sequentially passes through a constant temperature box with the length of 15m at 20 ℃, 22 ℃, 26 ℃, 32 ℃ and 36 ℃ along with the PE membrane, wherein the humidity of air is 50 percent, and the running speed of a stainless steel belt is 8.83 m/h;

(4) and (3) surface treatment of an NC film: a step of hot water treatment, in which the NC film slides into a hot water tank 1 with a water temperature of 63 ℃, two thirds of the hot water in the hot water tank 1 is replaced by fresh pure water every 24 hours, the treatment time of the NC film in the hot water tank 1 is 5min, and the NC film slides into PBS treatment liquid after passing through the hot water tank 1;

treating with PBS (phosphate buffer solution), wherein an NC (numerical control) membrane passes through a first surface treatment tank 2 and a second surface treatment tank 3 in sequence, and passes through the PBS treatment solution in the first surface treatment tank 2, wherein the pH value of the PBS treatment solution is 7.4; every 3 hours, the pH of the PBS treatment solution in the first surface treatment tank 2 was measured so that the pH was maintained at 7.0 to 7.5, and the amount of the new PBS treatment solution added was determined based on the solute in the PBS treatment solution adsorbed by the NC membrane during 3 hours so that the solute in the PBS treatment solution in the first surface treatment tank 2 was kept constant.

When the first surface treatment tank 2 is replaced with a new PBS treatment liquid, the PBS treatment liquid is added into the second surface treatment tank 3, then the PBS treatment liquid in the first surface treatment tank 2 is emptied, the tank body of the first surface treatment tank 2 is cleaned and disinfected, and the PBS treatment liquid in the second surface treatment tank 3 is used for treating the NC membrane surface, so that the replacement of the PBS treatment liquid in the first surface treatment tank 2 or the second surface treatment tank 3 is completed in a circulating manner.

(5) The NC film was dried in an oven at 45 ℃ and wound up.

Example 2

The difference between the embodiment 2 and the embodiment 1 is that 110L of acetone is measured in the step (1) and poured into a liquid preparation tank, 25kg of nitrocotton is added, a stirrer is started for 65r/min and stirred for 3 hours, and then 40L of ethanol, 50L of n-butanol and 6L of glycerol are added and stirred continuously for 3 days. Observing the condition of solid matters in the stirred sample to complete the dissolution of the membrane paddle;

in the step (3), the humidity of the air is 65%;

in the step (4), the temperature of the water for the NC membrane hot water treatment is 60 ℃.

Example 3

The difference between the embodiment 3 and the embodiment 1 is that 90L of acetone is measured in the step (1) and poured into a liquid preparation tank, 27kg of nitrocotton is added, a stirrer is started for 65r/min and stirred for 3 hours, and then 50L of ethanol, 40L of n-butanol and 6L of glycerol are added and stirred continuously for 3 days. Observing the condition of solid matters in the stirred sample to complete the dissolution of the membrane paddle;

in the step (4), the water temperature for the NC membrane hot water treatment is 66 ℃.

Example 4

The difference between the embodiment 4 and the embodiment 1 is that 100L of acetone is measured in the step (1) and poured into a liquid preparation tank, 22kg of nitrocotton is added, a stirrer is started for 65r/min and stirred for 3 hours, and then 45L of ethanol, 40L of n-butanol and 6L of glycerol are added and stirred continuously for 3 days. Observing the condition of solid matters in the stirred sample to complete the dissolution of the membrane paddle;

in the step (3), the humidity of the air is 40%;

example 5

The difference between the embodiment 5 and the embodiment 1 is that 110L of acetone is measured in the step (1) and poured into a liquid preparation tank, 25kg of nitrocotton is added, a stirrer is started for 65r/min and stirred for 3 hours, and then 40L of ethanol, 50L of n-butanol and 10L of glycerol are added and stirred continuously for 3 days. Observing the condition of solid matters in the stirred sample to complete the dissolution of the membrane paddle;

Comparative example 1

Comparative example 1 is different from example 1 in that the solvent acetone was added in an amount of 150L, and other conditions were the same as in example 1.

Comparative example 2

Comparative example 2 is different from example 1 in that the solvent acetone was added in an amount of 80L, and other conditions were the same as in example 1.

Comparative example 3

Comparative example 3 is different from example 1 in that the temperature of water during the hot water treatment of step (4) is set to normal temperature, and other conditions are the same as example 1.

TABLE 1 comparison of the process step conditions and the results of the products under NC film lamp inspection in examples 1 to 5 and comparative examples 1 to 3

From the process conditions and NC film results in table 1, the process conditions of examples 1-5 all meet the quality requirements for NC production.

In the examples 1-3, the content of acetone in different solvents is tested, and the NC film which has a smooth surface, no defects, dampness, mildew and the like, is smooth in surface, has no bubbles, wiredrawing, black spots and light reflection and meets the production requirements is prepared by the acetone within the range of 90-110L. Among them, the type a + NC film was obtained in the production methods of examples 1 to 3, and the quality of the NC film was high.

Meanwhile, in the examples 1-3, the water temperature of hot water treatment in the NC membrane surface treatment is changed, and the production quality of the prepared NC membrane meets the production quality requirement within the range of 60-66 ℃.

Examples 2 to 4 changed and adjusted the relative humidity of air in the coating and forming process of the NC film, and the NC film prepared in the range of the relative humidity of air of 40% to 65% all satisfied the production quality requirement, and the preparation method of example 4 was adopted to prepare the type B NC film, and the quality of the NC film was better.

Compared with the example 1, the content of the raw materials in the NC membrane pulp is changed in the example 5, the NC prepared under the condition also meets the production requirement, and the type-A NC membrane can be prepared by adopting the preparation mode of the example 5.

Comparative example 1 compared with example 1, the addition amount of acetone is increased in comparative example 1, the acetone content reaches 150L in the process of preparing the membrane pulp of the NC membrane, the content of solvent acetone is too high in the process of preparing the NC membrane, the acetone in the NC membrane is more in residue content in the NC membrane after coating and forming, the reflection phenomenon appears on the surface of the NC membrane, and the production requirement is not met.

The amount of acetone added in comparative example 2 was 80L, and the amount of acetone added in comparative example 2 was reduced compared to that in example 1, and it was found that the NC film produced a laminate and did not meet the quality requirements for NC film production.

Comparative example 3 compared to example 1, only the hot water at 63 ℃ in the hot water treatment was replaced by the normal temperature water, under the condition, the prepared NC film still contains a small amount of impurities on the surface, the quality of the NC film is affected, and it is found that bacteria are generated in the water tank when the normal temperature water treatment is used for a period of time, and the water tank needs to be cleaned and cleaned in time for many times.

In order to further investigate the factors affecting the quality of the NC film and the influence of impurities on the capillary migration effect of the NC film, the NC films prepared in example 1 and comparative example 3 were selected for the test of the capillary migration effect. Referring to fig. 3, the NC film prepared in comparative example 3 is the NC film numbered 1 in fig. 3, and is prepared at normal temperature; the NC film prepared in example 1 is the NC film designated as 2 in fig. 3, and is prepared by being subjected to hot water treatment. FIG. 3A is a schematic diagram showing a state before the adsorption of the NC membrane, and FIG. 3B is a schematic diagram showing a state after the adsorption of the NC membrane, wherein under the same conditions and time conditions, the running time of water on the NC membrane of reference numeral 2 is faster; because the NC membrane of the label 1 has impurities, the liquid level of water is inclined or not absorbed in a horizontal mode when the NC membrane of the label 1 runs, the application of the NC membrane is influenced, and the production requirement is not met.

Comparative example 4

Comparative example 4 is different from example 1 in that, in step (4), the NC film passes through only the first surface treatment bath 2 or the second surface treatment bath 3. In the production exemplified by the first surface treatment tank 2, in the step (4), the NC film passes through only the first surface treatment tank 2, and the NC film passes through the PBS treatment liquid in the first surface treatment tank 2, the pH of the PBS treatment liquid being 7.4;

after 24 hours of use, when the first surface treatment tank 2 was changed to the PBS treatment solution, two thirds of the PBS treatment solution in the first surface treatment tank 2 was discharged, and then the same volume as the discharged PBS treatment solution was added, so that the solute content in the PBS treatment solution in the first surface treatment tank 2 was kept constant, and the change of the PBS treatment solution in the first surface treatment tank 2 was completed. In this process, the process of changing the PBS treatment fluid is relatively cumbersome, and in this process, it is difficult to thoroughly clear away the impurities contained in the PBS treatment fluid in the first surface treatment tank 2, and the impurities can breed some microorganisms, which affects the quality of the NC membrane.

In addition, in the application, in the process of coating and forming the NC film, a stage-type constant temperature rise mode is adopted, and when the temperature is set to be higher than 40 ℃, the prepared NC film has more bubbles, so that the limitation of production on the bubble content cannot be met, the quality of the NC film is influenced, and the production requirement cannot be met.

In the hot water treatment test process, the test is carried out by adopting the water temperature of more than 66 ℃, and when the water temperature of the hot water is higher than 66 ℃, the impurities of the NC membrane can be washed away, so that the PBS treatment liquid components required by the surface of the subsequent treatment membrane are protected. However, in actual production requirements, when the temperature is high, hot water volatilizes quickly, the volatilization of the hot water can affect the air humidity for producing the NC membrane, a large amount of electric energy is consumed, the production cost is improved, and the temperature condition of more than 66 ℃ is not adopted from the production perspective.

Application example 1

In order to measure the quality of the NC film prepared in example 1, the NC film prepared in example 1 was selected and subjected to capillary migration, antibody streaking effect, and protein adsorption experiment.

Table 2 application test experiment of NC film in example 1

In table 2, the capillary migration speed and the appearance test both meet the production requirements, the NC membrane in example 1 has fewer impurities, and the antibody streaking effect and the protein adsorption experiment effect are both excellent, and the production process for preparing the NC membrane in example 1 can be popularized and applied in a large scale, and has a good application prospect.

In actual production, NC films prepared by the present application have been put on the market, and the prepared NC films are classified in the following manner:

class A + is: the thickness of the coating layer with the backing is 0.115-0.175mm except the backing; the error of the same plate is less than or equal to 0.01 mm; the error of the same volume number is less than or equal to 0.02 mm; the error of the same batch is less than or equal to 0.03 mm; the sum of other poor quality is not more than 1%;

a type: the thickness of the coating layer with the backing is 0.115-0.175mm except the backing; the error of the same plate is less than or equal to 0.02 mm; the error of the same number is less than or equal to 0.03 mm; the error of the same batch is less than or equal to 0.04 mm; the sum of other poor quality is not more than 5%;

b type: the thickness of the coating layer except the backing layer with the backing layer ranges from 0.105 mm to 0.175 mm; the error of the same plate is less than or equal to 0.02mm, and the error of the same coil number is less than or equal to 0.04 mm; the error of the same batch is less than or equal to 0.05 mm.

In the production process, the hot water treatment of the NC membrane is added, the first surface treatment groove 2 or the second surface treatment groove 3 which is convenient for replacing PBS treatment liquid is arranged, the impurities of PBS treatment in the first surface treatment groove 2 or the second surface treatment groove 3 are reduced, and the yield of products is greatly improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. A nitrocellulose membrane preparation process, characterized by comprising:

(1) preparing a nitrocellulose membrane paddle;

(2) filtering the membrane paddle in the step (1);

(5) the NC film was dried.

2. The process of claim 1, wherein the nitrocellulose membrane slurry comprises the following raw materials in parts by volume: 90-110L of solvent, 40-50L of cosolvent, 40-50L of nonsolvent and 5-10L of glycerol;

also comprises nitrocotton, and the weight of the nitrocotton is 22-27 kg.

3. The process of claim 1, wherein the solvent comprises one or more of methyl acetate, ethyl acetate, acetone, and methyl ethyl ketone; the cosolvent comprises any one or more of methanol and ethanol; the non-solvent includes any one or more of n-butanol and isobutanol.

4. The preparation process of the nitrocellulose membrane of claim 1, wherein the hot water treatment temperature is 60-66 ℃, and the hot water treatment time of the NC membrane is more than 1 min.

5. The process for preparing a nitrocellulose membrane of claim 1, wherein the membrane paddle is gradually baked from 19-21 ℃ to 34-36 ℃ in the coating and forming process, and the relative humidity of air is 40% -65%.

6. The process of claim 5, wherein in the coating and forming process, the NC film sequentially passes through thermostats with the temperatures of 20 +/-1 ℃, 22 +/-1 ℃, 26 +/-2 ℃, 32 +/-1 ℃ and 35 +/-1 ℃.

7. The process for preparing a nitrocellulose membrane according to claim 1, wherein in the surface treatment process of the PBS treatment solution, the NC membrane passes through the first surface treatment tank and the second surface treatment tank in sequence, and the pH of the PBS treatment solution is 7.0 to 7.5; when the PBS treatment liquid in the first surface treatment tank is replaced, the PBS treatment liquid is injected into the second surface treatment tank, and then the PBS treatment liquid in the first surface treatment tank is emptied.

8. The process of claim 1, wherein the membrane paddle after filtration in step (2) is left for 2-4 days.

9. The process for preparing a nitrocellulose membrane of claim 3, wherein the nitrocellulose membrane paddle is prepared by the following steps:

(b) adding ethanol, n-butanol and glycerol, stirring for 2-3 days.