CN111690195B

CN111690195B - Nano microporous membrane, and preparation method and application thereof

Info

Publication number: CN111690195B
Application number: CN202010372403.4A
Authority: CN
Inventors: 翁星星; 张叶青; 陈朝晖; 贡晶晶; 李正林
Original assignee: Jiangsu Housheng New Energy Technology Co Ltd
Current assignee: Jiangsu Housheng New Energy Technology Co Ltd
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2022-12-02
Anticipated expiration: 2040-05-06
Also published as: CN111690195A

Abstract

The invention discloses a method for manufacturing a nano microporous membrane for a medical anti-virus mask, which comprises the following raw materials in percentage by mass: polyolefin: 21.3 to 30 parts of processing aid: 70 to 78.5 parts of plasticizer; 0.02 to 0.1 portion; an antioxidant; 0.03 to 0.2 portion of lubricant; 0.04 to 0.15 part, wherein the molecular weight of the polyolefin is 60 to 150 ten thousand. According to the invention, polyolefin with a certain molecular weight and a processing aid are mixed according to a certain proportion, so that the compounded material meets the specific strength requirement, under the action of intermolecular force and an additive, the pore diameter of a microporous structure formed by stretching a polyolefin casting base film is greatly reduced, the pore diameter can reach a nanometer level, the 100% protection effect can be realized, and meanwhile, the thickness of the microporous film can be reduced, so that the mask material is more comfortable to wear.

Description

Nano microporous membrane, and preparation method and application thereof

Technical Field

The invention relates to the field of design of medical anti-virus masks, in particular to a nano microporous membrane, a manufacturing method of the nano microporous membrane and application of the nano microporous membrane.

Background

The medical mask is generally a multi-layer structure, and is generally referred to as an SMS structure. The material is a spun-bonded non-woven fabric, a melt-blown non-woven fabric and a spun-bonded non-woven fabric, which are called SMS structures for short. At present, the main material of the melt-blown non-woven fabric is polypropylene, and the melt-blown non-woven fabric is superfine electrostatic fiber cloth and can capture dust. When the droplets containing bacteria and viruses approach the melt-blown nonwoven fabric, the droplets are electrostatically adsorbed on the surface of the nonwoven fabric and cannot permeate through the nonwoven fabric. This is the principle of this material to isolate pathogens.

The most important thing in the mask is that the barrier layer is a melt-blown layer M (Meltblown), and the fiber diameter of the melt-blown layer is about 2 microns. The pore forming of the melt-blown layer M is smaller than that of the spun-bonded layer S, is rich in electrostatic capture effect, and is a core component for the mask to play a role. But is limited by the current spinning technology, the fiber diameter can only realize 2 microns production, and can not be further refined, thereby further reducing the pore diameter and leading the pore diameter to reach the virus diameter range. The aperture of the melt-blown layer M is basically 100nm to 200nm, and the diameter of most of the viruses is 50-100nm at present, which is just smaller than the aperture size of the medical mask at present, so that a certain hidden danger is buried for the invasion of the viruses. Therefore, the search for a microporous membrane with thinner and smaller pore size to block the virus 100% is an important development direction for high-end hospital masks.

Disclosure of Invention

In order to solve the technical problems that the aperture of a melt-blown layer for a medical anti-virus mask in the prior art is larger than the aperture of virus and the virus cannot be blocked by 100 percent, the invention provides a nano microporous membrane, a manufacturing method of the nano microporous membrane and application of the nano microporous membrane to solve the problems.

The invention provides a nano microporous membrane, which adopts the following raw materials in percentage by mass: polyolefin: 21.3 to 30 parts of processing aid: 70-78.5 parts of a plasticizer; 0.02 to 0.1 portion; an antioxidant; 0.03 to 0.2 part by weight of a lubricant; 0.04 to 0.15 part, wherein the molecular weight of the polyolefin is 5 to 150 ten thousand.

Further, the polyolefin is polyethylene or polypropylene.

Further, the processing aid is paraffin oil, and the molecular weight of the paraffin oil is 100 to 500g/mol.

Furthermore, the plasticizer is one or a mixture of more of phthalic acid esters, aliphatic dibasic acid esters and phosphate esters. The phthalate specifically refers to dioctyl phthalate (DOP), the aliphatic dibasic acid ester specifically refers to dioctyl acetate (DOA), and the phosphate specifically refers to trioctyl phosphate (TOP).

Preferably, the antioxidant is a mixture of one or more phenolic antioxidants, and the mixture of the plurality of antioxidants can achieve the effect of synergistic antioxidation.

Preferably, the lubricant is a stearic acid-based polymer compound.

The invention also provides a manufacturing method of the nanometer microporous membrane, which comprises the following steps:

s1: preparing raw materials; mixing polyolefin, a plasticizer, an antioxidant and a lubricant according to the mass fraction ratio of each component in the nano microporous membrane, stirring uniformly at the temperature of 20-50 ℃, adding into an extrusion device, and then adding a processing aid according to the ratio.

S2: extrusion molding; and (3) melting and extruding the mixture in the step S1 from a double-screw extruder, and then casting and forming by casting rolls to obtain the polyolefin casting base film.

S3: stretching; at 90-110 ℃, firstly longitudinally stretching the cast base film, and then transversely stretching to obtain the polyolefin microporous film with a microporous structure.

S4: and (3) secondary stretching: firstly, adding a volatile reagent on a polyolefin microporous membrane, extracting high-boiling-point solvent white oil in the polyolefin microporous membrane by using an extraction process, then transversely stretching again at 100-120 ℃, and drying and corona-treating to obtain the high-molecular nano microporous membrane.

Preferably, the extrusion apparatus in step S1 is a twin-screw extruder.

Preferably, the volatile agent in step S4 is dichloromethane.

The invention also provides the application of the nano microporous membrane prepared by the method in the medical anti-virus mask.

The invention has the beneficial effects that:

(1) According to the invention, polyolefin with a certain molecular weight and a processing aid are mixed according to a certain proportion, so that the compounded material meets the specific strength requirement, under the action of intermolecular force and an additive, the pore diameter of a microporous structure formed by stretching a polyolefin casting base film is greatly reduced, the pore diameter can reach the nanometer level, the 100% protection effect can be realized, and meanwhile, the thickness of the microporous film can be reduced, so that the mask material is more comfortable to wear.

(2) The plasticizer and the antioxidant are added in the raw materials, so that the flexibility of the raw materials is enhanced, the raw materials are easier to process, the influence of air on the performance of the raw materials can be reduced by the antioxidant, and the product stability is better.

(3) The nanometer microporous membrane is formed by two times of stretching, after the polyolefin microporous membrane is formed by the first stretching, white oil with high boiling point is extracted by adopting an extraction process, the proportion of polyolefin in the nanometer microporous membrane is higher, and the intermolecular force is larger.

(4) The method of the invention can adopt two main materials of polypropylene and polyethylene to process the nanometer microporous membrane, breaks through the limitation that only polypropylene is used for manufacturing melt-blown non-woven fabrics in the prior art, improves the selectivity of product raw materials, and thus can greatly reduce the product cost.

Detailed Description

The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention.

The microporous nano-membrane is prepared from the following raw materials in percentage by mass: polyolefin: 21.3 to 30 parts of processing aid: 70-78.5 parts of a plasticizer; 0.02 to 0.1 part; an antioxidant; 0.03 to 0.2 part by weight of a lubricant; 0.04 to 0.15 part, wherein the molecular weight of the polyolefin is 5 to 150 ten thousand.

The processing aid is a high-viscosity aid, and the intermolecular force of the raw material obtained by mixing the processing aid and the polyolefin with a certain molecular weight is higher, and the toughness is better.

The polyolefin is typically polyethylene or polypropylene.

The processing aid can be paraffin oil, and the molecular weight of the paraffin oil is preferably 100 to 500g/mol.

The more the molecular weight, the larger the intermolecular acting force, the higher the strength, the better the structural stability, on the other hand, the more the molecular weight, the larger the melt index, the higher the processing difficulty, so the molecular weight of the polyolefin and the paraffin oil needs to be reasonably selected.

Preferably, the number of carbon chains of the paraffin oil is between 6 and 40, the paraffin oil is a low molecular oil subjected to complete isomerization, and the higher the number of carbon chains is, the lower the boiling point of the paraffin oil is, the more easily the paraffin oil is volatilized in the processing process of the nano microporous membrane, and the solvent concentration is reduced; conversely, the lower the number of carbon chains, the higher the boiling point of the paraffinic oil, the better the stability of the paraffinic oil, but the higher the material cost, so the rational selection of the number of carbon chains of the paraffinic oil is required.

The plasticizer is one or more of phthalate, aliphatic dibasic acid ester and phosphate. The plasticizer has a plasticizing effect, so that the flexibility of the raw material can be enhanced, and the processing is easier. The phthalate plasticizer is preferably dioctyl phthalate (DOP), the aliphatic dibasic acid ester plasticizer is preferably dioctyl ethylene oxide (DOA), and the phosphate plasticizer is preferably trioctyl phosphate (TOP).

The antioxidant is a mixture of one or more phenolic antioxidants, and the effect of synergistic antioxidation can be achieved by mixing a plurality of antioxidants.

The lubricant is preferably a stearic acid-based high molecular compound, and is used for reducing friction between films or between a thin film and processing equipment.

A manufacturing method of a nanometer microporous membrane comprises the following steps:

S2: extrusion molding; and (3) melting and extruding the mixture in the step S1 from a double-screw extruder, and then casting and forming by a casting roll to obtain the polyolefin casting base film.

The extrusion device in step S1 is a twin-screw extruder.

The melt extrusion process was as follows: and (2) melting and extruding the raw material mixture in the step (S1) at 180-260 ℃ by using a double-screw extruder, carrying out tape casting film formation through a tape casting die head or an annular blow molding die, and drawing at a certain speed after cooling (such as forced cooling) to obtain the polyolefin tape casting base film with uniform thickness. Specifically, the melt extrusion can be carried out by a single-screw or double-screw extruder, and the extrusion temperature is not lower than 190 ℃ in consideration of the molding processing and plasticizing performance of the material. The roller temperature for casting film forming is 30-100 ℃, the production line speed is 60-120 kg/h, and the forming thickness is 10-40 microns.

After casting film forming, the obtained polyolefin casting base film can be further subjected to heat treatment, so that the crystallinity of the base film and the integrity of a wafer are further improved, the heat treatment temperature is 110-150 ℃, and the heat treatment time is 10 minutes-15 hours.

According to the invention, the reagent with a lubricating effect is added into the raw materials firstly, so that the stirring and mixing of the raw materials are facilitated, the raw materials can be more smoothly and smoothly extruded, the white oil is extracted by using the volatile reagent after primary stretching, the volatile reagent used during extraction is dichloromethane, the lubricating component of the polyolefin microporous membrane subjected to the extraction process is reduced, the polyolefin proportion is increased, the intermolecular force is also increased, at the moment, the polyolefin microporous membrane can be stretched again on the basis of the polyolefin microporous membrane, and the pore diameter of the stretched polyolefin microporous membrane can still keep a small size due to the existence of large intermolecular force.

The nano microporous membrane prepared by the method can be used as a barrier layer to be applied to a medical anti-virus mask.

Various suitable compositions, fabrication methods, and performance test results for nanopore membranes are illustrated by the following examples.

Example 1

The raw material components are as follows: polyethylene with the molecular weight of 60 ten thousand, 250ppm of plasticizer, 400ppm of antioxidant, 500ppm of lubricant, 400g/mol of paraffin oil, and the mass fraction ratio of paraffin oil to polyethylene is 7:3, the total weight of the mixed raw materials is 20g, a double-screw extruder is used for melt extrusion, the mixture is cast into a thick film, the extrusion temperature is 220 ℃, the extrusion amount is 120kg/h, the casting temperature is 60 ℃, and the thickness of the thick film formed by casting is 30um. The longitudinal stretching ratio is 10 times of stretching ratio, the longitudinal stretching temperature is 90 ℃, the primary transverse stretching ratio is 10 times of stretching ratio, the primary transverse stretching temperature is 100 ℃, the extraction temperature is 15 ℃, the secondary transverse stretching ratio is 10 times of stretching ratio, the secondary transverse stretching temperature is 120 ℃, and the polymer nano microporous membrane is obtained after drying, wherein the thickness of the nano microporous membrane is 5 microns. Tests prove that the microporous membrane manufactured by the embodiment has the overall pore diameter of less than 100nm, only a small amount of pore diameter of more than 100nm and the average pore diameter of 52nm, and shows effective physical isolation on various viruses.

Example 2

The raw material components are as follows: polyethylene with the molecular weight of 150 ten thousand, plasticizer 600ppm, antioxidant 800ppm, lubricant 1000 ppm, paraffin oil with the molecular weight of 200g/mol, and the mass fraction ratio of paraffin oil to polyethylene is 7:3, the total weight of the mixed raw materials is 20g, a double-screw extruder is used for melt extrusion, the mixture is cast into a thick film, the extrusion temperature is 220 ℃, the extrusion amount is 60kg/h, the casting temperature is 60 ℃, and the thickness of the cast thick film is 30um. The longitudinal stretching ratio is 7 times of stretching ratio, the longitudinal stretching temperature is 95 ℃, the primary transverse stretching ratio is 10 times of stretching ratio, the primary transverse stretching temperature is 115 ℃, the extraction temperature is 20 ℃, the secondary transverse stretching ratio is 10 times of stretching ratio, the secondary transverse stretching temperature is 115 ℃, and the polymer nano microporous membrane is obtained after drying, wherein the thickness of the nano microporous membrane is 2 mu m. The average pore diameter was measured to be 64nm.

Example 3

The raw material components are as follows: polyethylene with a molecular weight of 60 ten thousand (melt index of 60), plasticizer 800ppm, antioxidant 1500ppm, lubricant 1200 ppm, paraffin oil with a molecular weight of 600g/mol, paraffin oil and polyethylene mass fraction ratio of 3:1, the total weight of the mixed raw materials is 20g, a double-screw extruder is used for melt extrusion and casting to form a thick film, the extrusion temperature is 220 ℃, the extrusion amount is 80kg/h, the casting temperature is 60 ℃, and the thickness of the cast thick film is 30 mu m. The longitudinal stretching ratio is 8 times of stretching ratio, the longitudinal stretching temperature is 90 ℃, the primary transverse stretching ratio is 10 times of stretching ratio, the primary transverse stretching temperature is 110 ℃, the extraction temperature is 18 ℃, the secondary transverse stretching ratio is 10 times of stretching ratio, the secondary transverse stretching temperature is 110 ℃, and the polymer nano microporous membrane is obtained after drying, wherein the thickness of the nano microporous membrane is 4 mu m. The average pore diameter was tested to be 71nm.

Example 4

The raw material components are as follows: polypropylene with the melt index of 2g/10min, 900ppm of plasticizer, 1800ppm of antioxidant, 1400 ppm of lubricant, 200g/mol of paraffin oil molecular weight, and 3 mass percent of paraffin oil and polyethylene: 1, the total weight of the mixed raw materials is 20g, a double-screw extruder is used for melt extrusion, the mixture is cast into a thick film, the extrusion temperature is 220 ℃, the extrusion amount is 70kg/h, the casting temperature is 60 ℃, and the thickness of the thick film formed by casting is 30um. The longitudinal stretching ratio is 9 times of stretching ratio, the longitudinal stretching temperature is 100 ℃, the primary transverse stretching ratio is 10 times of stretching ratio, the primary transverse stretching temperature is 120 ℃, the extraction temperature is 20 ℃, the secondary transverse stretching ratio is 10 times of stretching ratio, the secondary transverse stretching temperature is 120 ℃, and the polymer nano microporous membrane is obtained after drying, wherein the thickness of the nano microporous membrane is 3 mu m. The average pore diameter was tested to be 63nm.

The results of measuring various parameters of the nanopore membranes prepared in examples 1 to 4 are shown in table 1, and it can be seen that the nanopore membranes prepared by the method of the present invention under different mixture ratios have the following advantages compared with the prior art: (1) The aperture is small, the aperture is below 100nm, even can reach 50nm, the virus can be blocked by 100 percent, and a better protection function is embodied (the aperture of the melt-blown layer of the existing mask is 100-200 nm); (2) The thickness is as thin as 2-7um, which is one tenth of the thickness of the melt-blown layer of the existing mask, and the mask made of the mask is more comfortable to wear (the thickness of the melt-blown layer of the existing mask is 20-40 um); (3) The tensile strength is high, the tensile strength reaches more than 200MPa, and higher safety is realized (the strength of a melt-blown layer of the existing mask is about 100 MPa). And (4) the electrostatic effect is better, and the virus capture capacity is higher.

TABLE 1

In addition, comparing example 1 and example 2, the polyethylene in example 2 has a larger molecular weight, higher intermolecular forces, and better toughness, so example 2 can be stretched thinner. Similarly, in example 1, compared with example 3, the polyethylene in example 3 is larger, and the microporous membrane has better overall toughness. In example 4, polypropylene was used instead of polyethylene, and the method of the present invention was also used to produce microporous nanopores with more optimized properties.

In this specification, the schematic representations of the terms are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A manufacturing method of a nanometer microporous membrane for a medical anti-virus mask is characterized in that the nanometer microporous membrane adopts the following raw materials in parts by mass:

polyolefin: 21.3 to 30 parts of (A) to (B),

processing aid: 70 to 78.5 parts of (C),

a plasticizer; 0.02 to 0.1 portion;

an antioxidant; 0.03 to 0.2 portion of,

a lubricant; 0.04 to 0.15 part, wherein the molecular weight of the polyolefin is 60 to 150 ten thousand;

the processing aid is paraffin oil, and the molecular weight of the paraffin oil is 100 to 500g/mol;

the plasticizer is one or a mixture of more of phthalic acid esters, aliphatic dibasic acid esters and phosphate esters;

the method comprises the following steps:

s1: preparing raw materials; mixing polyolefin, a plasticizer, an antioxidant and a lubricant according to the mass part ratio of each component in the nano microporous membrane, uniformly stirring at the temperature of 20-50 ℃, adding into an extrusion device, and then adding a processing aid according to the ratio;

s2: extrusion molding; the mixture in the step S1 is melted and extruded from a double-screw extruder, and then cast by a casting roll to form a polyolefin casting base film;

s3: stretching; at 90-110 ℃, firstly longitudinally stretching the cast base film, and then transversely stretching with the transverse stretching magnification of 10 times to obtain a polyolefin microporous film with a microporous structure;

s4: and (3) secondary stretching: firstly, adding a volatile reagent on a polyolefin microporous membrane, extracting paraffin oil in the polyolefin microporous membrane by using an extraction process, then transversely stretching at 100-120 ℃ again, wherein the transverse stretching magnification is 10 times, and drying and corona-treating to obtain the polymer nano microporous membrane.

2. The method for manufacturing a nanopore membrane for a medical anti-virus mask according to claim 1, wherein the method comprises the following steps: the polyolefin is polyethylene or polypropylene.

3. The method for manufacturing a nanopore membrane for a medical anti-virus mask according to claim 1, wherein the method comprises the following steps: the antioxidant is a mixture of one or more phenolic antioxidants.

4. The method for manufacturing a nanopore membrane for a medical anti-virus mask according to claim 1, wherein the method comprises the following steps: the lubricant is a stearic acid polymer compound.

5. The method for manufacturing a nanopore membrane for a medical anti-virus mask according to claim 1, wherein the method comprises the following steps: the extrusion device in step S1 is a twin-screw extruder.

6. The method for manufacturing a nanopore membrane for a medical anti-virus mask according to claim 1, wherein the method comprises the following steps: the volatile reagent in step S4 is dichloromethane.