CN111154123A

CN111154123A - Method for continuously preparing large-aperture nitrocellulose membrane

Info

Publication number: CN111154123A
Application number: CN202010035150.1A
Authority: CN
Inventors: 吴昊
Original assignee: Shanghai Xinya Purification Device Factory
Current assignee: Shanghai Xinya Purification Device Factory
Priority date: 2020-01-14
Filing date: 2020-01-14
Publication date: 2020-05-15

Abstract

The invention discloses a method for continuously preparing a large-aperture nitrocellulose membrane, which comprises the following steps: adding a cosolvent, a surfactant, water and a high polymer material cellulose nitrate into a reaction kettle for mixing, adding a solvent after mixing, and dissolving and stirring at normal temperature; then defoaming and filtering to obtain a uniform casting solution for later use; casting the casting solution by a casting machine; evaporating and forming the wet film after casting through an evaporation section; drying, drying in a drying section after film forming, and rolling after drying to obtain the large-aperture nitrocellulose membrane; the continuous operation of the casting machine can continuously cast the large-aperture nitrocellulose membrane. The invention improves the raw material proportion and the film forming process, and can produce stable, uniform and firm nitrocellulose films. The preparation of the casting solution and the control of the precise casting machine on the film forming conditions form a stable and uniform film, the cleaning and the dust removal are not needed, and the film has natural permanent hydrophilicity and can be used for high-requirement in-vitro diagnosis test paper strips.

Description

Method for continuously preparing large-aperture nitrocellulose membrane

Technical Field

The invention relates to the technical field of nitrocellulose membranes, in particular to a method for continuously preparing a large-aperture nitrocellulose membrane.

Background

The nitrocellulose membrane is also called NC membrane, is used as a carrier of a C/T line in the colloidal gold test paper, and is also a place for immunoreaction. Therefore, the NC film becomes the most important consumable in the test. Nitrocellulose membrane is currently one of the most widely used solid supports. Nitrocellulose membranes, by virtue of their good hydrophobic interaction, can produce high affinity adsorption to most negatively charged DNA, RNA, and proteins. After adsorption, the polymer can be fixed by baking at 80 ℃ or crosslinking through ultraviolet irradiation. Because of this property, nitrocellulose membranes have been widely used in the fields of biochemistry and molecular biology, mainly in the fields of molecular hybridization, immunoblotting, cell culture, and medical diagnosis. At present, the conventional nitrocellulose membrane has poor performance and uneven thickness, the diffusivity of biological raw materials on the membrane is used in the hard later period, and the manufactured membrane has more dust and poor adsorptivity and uniformity. The existing similar products basically depend on imports. Some domestic products are not on the market yet and are immature, so that various problems exist: the membrane is not firm, the larger aperture can not be made, the membrane structure is not uniform, the membrane is not hydrophilic, the surface of the membrane is full of dust, the upper part and the lower part are not symmetrical, and the like.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for continuously preparing a large-aperture nitrocellulose membrane, which continuously produces a membrane with stable performance.

In order to achieve the purpose of the invention, the invention adopts the technical scheme that:

a method for continuously preparing a large-aperture nitrocellulose membrane comprises the following steps:

step 1: preparing membrane slurry, preparing membrane liquid: adding a cosolvent, a surfactant, water and a high polymer material cellulose nitrate into a reaction kettle for mixing, adding a solvent after mixing for 1-10 hours, and dissolving and stirring for 24 hours at normal temperature; then defoaming and filtering to obtain a uniform casting solution for later use; step 2: casting the casting solution by a casting machine; and step 3: evaporating and forming the wet film after casting through an evaporation section; and 4, step 4: drying, drying in a drying section after film forming, and rolling after drying to obtain the large-aperture nitrocellulose membrane; and 5: the continuous operation of the casting machine can continuously cast the large-aperture nitrocellulose membrane.

Further, the casting solution in the step 1 comprises, by mass, 10% -30% of a cosolvent, 1% -10% of a surfactant, 1% -10% of water, 15% -30% of nitrocellulose, and 10% -50% of a solvent.

Further, the casting height in the step 2 is 100-1000 um.

Further, the evaporation condition in the step 3 is that the wind speed is 0.2-5 m/s, the air temperature is 10-70 degrees, and the humidity is 20-80 percent.

Further, the drying temperature in the step 4 is 10-130 degrees.

Further, the co-solvent includes, but is not limited to, methanol, ethanol, propanol, butanol, ethylene glycol.

Further, the surfactant includes, but is not limited to, PEG200, PEG400, PEG 800.

Further, the solvent includes, but is not limited to, dichloromethane, acetone, methyl acetate.

The invention has the beneficial effects that: the invention improves the raw material proportion and the film forming process, and can produce stable, uniform and firm nitrocellulose films. The preparation of the casting solution and the control of the precise casting machine on the film forming conditions form a stable and uniform film, the cleaning and the dust removal are not needed, and the film has natural permanent hydrophilicity and can be used for high-requirement in-vitro diagnosis test paper strips. The pore diameter of the membrane is 0.1-20 μm. Continuous production can be realized, and the product batches are stable and uniform; a clean, open large pore membrane can be formed without post-cleaning treatment; the produced film has strong membrane protein adsorbability.

Drawings

FIG. 1 is a plot of the pore size of a film produced according to the formulations and processes of the present application.

FIG. 2 is a diagram of the pore size of a film for a foreign brand A product.

FIG. 3 is a film pore size diagram of domestic replica B.

Detailed Description

In order to make the content of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

The first embodiment is as follows: preparation of large-aperture nitrocellulose membrane

Step 1: preparing membrane slurry, preparing membrane liquid: adding a cosolvent, a surfactant, water and a high polymer material cellulose nitrate into a reaction kettle for mixing, adding a solvent after mixing for 5.5 hours, and dissolving and stirring for 24 hours at normal temperature; then defoaming and filtering to obtain a uniform casting solution for later use; the casting solution in the step 1 comprises, by mass, 20% of a cosolvent, 5.5% of a surfactant, 5.5% of water, 22.5% of nitrocellulose, and 30% of a solvent. The cosolvent is ethanol, the surfactant is PEG400, and the solvent is acetone.

Step 2: casting the casting solution by a casting machine; the casting height in step 2 was 550 um.

And step 3: evaporating and forming the wet film after casting through an evaporation section; the evaporation conditions in step 3 are wind speed of 2.6m/s, air temperature of 40 ℃ and humidity of 50%.

And 4, step 4: drying, drying in a drying section after film forming, wherein the drying temperature in the step 4 is 70 degrees, and rolling after drying to obtain the large-aperture nitrocellulose membrane;

and 5: the continuous operation of the casting machine can continuously cast the large-aperture nitrocellulose membrane.

Example two: influence on film cleanliness

The formula and process are shown in detail in fig. 1, fig. 2 and fig. 3 for the film cleanliness test results.

FIG. 2 is a diagram of the pore size of a film for a foreign brand A product.

FIG. 3 is a film pore size diagram of domestic replica B.

The chart shows that the product is clean and has an open pore size diagram; foreign brand A products, because of the formulation and the process, the manufactured film has a spherical structure, which affects the film performance (adsorptivity, poor uniformity); in the domestic imitation B, due to the formulation and the process, the manufactured film has very much dust, and the performance of the film is influenced (the adsorbability and the uniformity are not good).

Example three: influence of different solvent formulas and component ratios on membrane pore diameter

The results of the influence of different solvent formulations and component ratios on the pore size of the nitrocellulose membrane are detailed in table 1.

TABLE 1 influence of different solvent formulations and component ratios on the pore size of nitrocellulose membranes

The above results show that pore size has the greatest effect on performance for nitrocellulose membranes.

The pore size is influenced most by different nitrocellulose contents and water contents, and the performance difference of the finally formed membrane is large.

The influence of the cosolvent and the solvent is not great, and the cosolvent and the solvent are selected to be used appropriately.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the present invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for continuously preparing a large-aperture nitrocellulose membrane is characterized by comprising the following steps:

step 1: preparing membrane slurry, preparing membrane liquid: adding a cosolvent, a surfactant, water and a high polymer material cellulose nitrate into a reaction kettle for mixing, adding a solvent after mixing for 1-10 hours, and dissolving and stirring for 24 hours at normal temperature; then defoaming and filtering to obtain a uniform casting solution for later use;

step 2: casting the casting solution by a casting machine;

and step 3: evaporating and forming the wet film after casting through an evaporation section;

and 4, step 4: drying, drying in a drying section after film forming, and rolling after drying to obtain the large-aperture nitrocellulose membrane;

2. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: the casting solution in the step 1 comprises, by mass, 10-30% of a cosolvent, 1-10% of a surfactant, 1-10% of water, 15-30% of nitrocellulose, and 10-50% of a solvent.

3. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: the casting height in the step 2 is 100-1000 um.

4. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: the evaporation conditions in the step 3 are that the wind speed is 0.2-5 m/s, the air temperature is 10-70 degrees, and the humidity is 20-80 percent.

5. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: the drying temperature in the step 4 is 10-130 degrees.

6. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: the co-solvent includes, but is not limited to, methanol, ethanol, propanol, butanol, ethylene glycol.

7. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: the surfactant includes, but is not limited to, PEG200, PEG400, PEG 800.

8. The method for continuously preparing the large-aperture nitrocellulose membrane according to claim 1, wherein: such solvents include, but are not limited to, dichloromethane, acetone, methyl acetate.