阅读说明：本技术 一种替代医用口罩熔喷布的生物质过滤膜材及制备方法 (Biomass filter membrane material for replacing medical mask melt-blown cloth and preparation method thereof ) 是由 曾军堂 陈庆 司文彬 白涛 于 2020-07-28 设计创作，主要内容包括：本发明提出一种替代医用口罩熔喷布的生物质过滤膜材及制备方法,所述生物质过滤膜材是将淀粉、聚乙烯醇、硼酸、纳米电气石、水、氢氧化钠先后加入高速混合机中,然后通过升温和开关排气孔进行混合搅拌得到混合物料,接着将物料密封保存后与EVA、N,N’-乙撑双硬脂酰胺、聚四氟乙烯微粉混合挤出发泡成片,再经拉伸、风冷、卷取而制得。本发明提供的生物质过滤膜材,过滤效率高,对微细微尘、病毒的过滤吸附聚集性强,可完全替代目前熔喷布用于医用口罩,同时工艺易控简单,微孔可控,设备投资极低,具有广阔应用前景。(The invention provides a biomass filter membrane material for replacing medical mask melt-blown cloth and a preparation method thereof, wherein the biomass filter membrane material is prepared by sequentially adding starch, polyvinyl alcohol, boric acid, nano tourmaline, water and sodium hydroxide into a high-speed mixer, then mixing and stirring the materials by heating and opening and closing an exhaust hole to obtain a mixed material, then mixing and extruding the mixed material, after the sealed storage of the material, EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder to form a foam sheet, and then stretching, air cooling and coiling the foam sheet. The biomass filtering membrane material provided by the invention has high filtering efficiency, strong filtering, adsorbing and gathering properties on micro-fine dust and viruses, can completely replace the prior melt-blown cloth to be used for medical masks, and has the advantages of easily controllable and simple process, controllable micropores, extremely low equipment investment and wide application prospect.)

1. A biomass filter membrane material for replacing medical mask melt-blown cloth is characterized in that the biomass filter membrane material is prepared by sequentially adding starch, polyvinyl alcohol, boric acid, nano tourmaline, water and sodium hydroxide into a high-speed mixer, then heating and opening and closing an exhaust hole to mix and stir to obtain a mixed material, then sealing and storing the mixed material, mixing the sealed and stored material with EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder, extruding and foaming the mixture into sheets, and then stretching, air cooling and coiling the sheets.

2. The biomass filter membrane material for replacing the medical mask melt-blown cloth according to claim 1, wherein the polyvinyl alcohol is PVA 1788.

3. The biomass filtering membrane material for replacing the medical mask melt-blown cloth according to claim 1, wherein the fineness of the nano tourmaline is 60-100 nm.

4. The preparation method of the biomass filter membrane material for replacing the medical mask melt-blown cloth according to any one of claims 1 to 3, is characterized by comprising the following steps:

(1) adding starch, polyvinyl alcohol, boric acid and nano tourmaline into a high-speed mixer, uniformly stirring at the temperature of 80-90 ℃, then adding sodium hydroxide into water to prepare an alkali liquor, then adding the alkali liquor into the high-speed mixer, closing an exhaust hole, continuously stirring for 15-25min to ensure that the alkali liquor fully permeates the starch and the polyvinyl alcohol, then heating the high-speed mixer to 110 ℃, simultaneously opening the exhaust hole to exhaust, reducing the moisture content of the materials, and then discharging to obtain a mixed material;

(2) and (3) sealing and storing the obtained mixed material, adding the sealed and stored material, EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder into a stirring kettle, uniformly mixing, extruding and foaming by using a single-screw extruder, longitudinally stretching a foamed sheet while the sheet is hot, air cooling and coiling to obtain the biomass filter membrane material for replacing medical mask melt-blown cloth.

5. The method for preparing the biomass filter membrane material for replacing the medical mask melt-blown cloth according to claim 4, wherein the moisture content of the material is reduced to 10-12% in the step (1).

6. The preparation method of the biomass filter membrane material for replacing the medical mask melt-blown cloth according to claim 4, wherein in the preparation of the mixed material in the step (1), the mass ratio of starch, polyvinyl alcohol, boric acid, nano tourmaline, water and sodium hydroxide is 20-30:3-5:0.02-0.05:0.1-0.2:10-15: 0.05-0.1.

7. The method for preparing the biomass filter membrane material for replacing the medical mask meltblown fabric according to claim 4, wherein the sealing preservation method in the step (2) is preservation by paper for 24-36 h.

8. The preparation method of the biomass filter membrane material for replacing the medical mask melt-blown cloth according to claim 4, wherein the single-screw extruder in the step (2) is a single-screw extruder with a short length-diameter ratio, the length-diameter ratio is controlled to be 10:1, and the extrusion die head is a die head with a gap of 1mm and a width of 200 mm.

9. The method for preparing the biomass filter membrane material for replacing the medical mask melt-blown cloth according to claim 4, wherein the stretching ratio of the longitudinal stretching in the step (2) is 3 to 5 times.

10. The preparation method of the biomass filter membrane material for replacing the medical mask melt-blown cloth according to claim 4, wherein in the preparation of the biomass filter membrane material in the step (2), the mass ratio of the hermetically stored material, EVA, N' -ethylene bis-stearamide and polytetrafluoroethylene micro powder is 80-90:3-5:1-2: 0.1-0.3.

Technical Field

The invention relates to the technical field of medical materials, in particular to a biomass filter membrane material for replacing medical mask melt-blown cloth and a preparation method thereof.

Background

The melt-blown fabric is a non-woven fabric with excellent filtering performance, is the most core material of the mask, mainly takes polypropylene as a main raw material, and the fiber diameter can reach 1-5 microns. The superfine fiber with the unique capillary structure increases the number and the surface area of the fiber per unit area, so that the melt-blown fabric has good filtering property, shielding property, heat insulation property and oil absorption property. Can be used in the fields of air and liquid filtering materials, isolating materials, absorbing materials, mask materials, warm-keeping materials, oil absorbing materials, wiping cloth and the like.

The filtration performance of the melt-blown cloth makes the melt-blown cloth have great potential in the fields of medical protection, environmental protection filtration and the like, and is the most important filtration material in medical masks and protective clothing at present. Although the melt-blown fabric has excellent filtering effect, the fibers are not drawn for a long time in the preparation process, the melt-blown fabric has low strength and abrasion resistance, and cannot bear strong external force independently, so that the prepared mask is easy to damage by external force and lose the protection capability, and is easy to stretch and deform, and therefore, the mask is often used as a disposable protection article and causes great waste.

Currently, most masks use a spunbond-meltblown-spunbond (SMS) composite product sandwiched with meltblown fabric. And in order to improve the filterability of the melt-blown fabric, electret treatment is also adopted. This complicates the production process of the medical mask. In addition, when the melt-blown fabric is manufactured, the used raw materials have higher requirements and strict requirements on the production process, and not only is the melt-blown fiber required to be uniformly spun, but also the fiber diameter is required to be thin, so that the material meeting the medical filtration can be obtained. For a long time, PP with a melt index of more than 1000g/10min is basically used in the field for melt-blown fabric preparation, and the supply of raw materials also becomes a bottleneck. According to the filtration characteristics of the meltblown fabric, the meltblown fabric has the main function of preventing external foreign matters such as particles, dust, bacteria, viruses and the like from entering a human body through a respiratory tract, and the meltblown fabric can be replaced as long as high filterability is met, so that the research on the substitute material of the meltblown fabric is concerned.

Chinese patent application No. 202010374866.4 discloses a preparation process of composite short fiber electret hot air non-woven fabric, which comprises the following steps: s1, mixing materials; s2, primary opening; s3, fine opening; s4, carding and lapping; s5, puncturing by hot air; and S6, pressing the hot-pressed fibers into a specified thickness after high-voltage electrostatic electret treatment, cutting edges, and rolling to obtain the composite short fiber electret hot-air non-woven fabric which can replace melt-blown fabric and meet market requirements. The Chinese patent application No. 202010193998.7 discloses an air filter medium and a preparation method thereof, the air filter medium comprises a base cloth and a barrier layer, the barrier layer comprises at least one layer of foam cell structure, the foam cell structure is formed by adding electret master batch into a water-based polyurethane system for foaming and then performing wet solidification, and at least part of the foam cells are communicated; solidifying the foaming layer by a condensation liquid, demulsifying and solidifying the waterborne polyurethane, fixing foam holes, evaporating water by heating, and compounding the remained compact foam holes with the base cloth to form an air filtering medium; the air filter medium has high particle blocking rate and simple preparation method, is applied to the field of masks instead of melt-blown cloth, and solves the problem of insufficient supply of the masks.

In order to solve the problems of high process requirement and high difficulty of raw materials for preparing the melt-blown cloth, a novel material for replacing the melt-blown cloth is necessary, and an excellent biomass filter material capable of replacing the melt-blown cloth of the medical mask is obtained.

Disclosure of Invention

Aiming at the problems that the preparation of the prior melt-blown cloth has higher requirements on raw material process, has high control difficulty on the fineness and the uniformity of melt-blown fibers and is easy to stretch and deform when a medical mask protective material is applied, the invention provides a biomass filter membrane material for replacing the melt-blown cloth of a medical mask and a preparation method thereof, thereby obtaining the melt-blown cloth substitute material with excellent filtering performance.

In order to solve the problems, the invention adopts the following technical scheme:

a biomass filter membrane material for replacing medical mask melt-blown cloth is prepared by sequentially adding starch, polyvinyl alcohol, boric acid, nano tourmaline, water and sodium hydroxide into a high-speed mixer, heating, opening and closing an exhaust hole, mixing and stirring to obtain a mixed material, sealing and storing the mixed material, mixing the sealed and stored material with EVA, N' -ethylene bis-stearamide and polytetrafluoroethylene micro powder, extruding, foaming into sheets, stretching, air cooling and coiling.

Preferably, the polyvinyl alcohol is under the trademark PVA 1788.

Preferably, the fineness of the nano tourmaline is 60-100 nm.

Further preferably, the nano tourmaline is tourmaline powder with fineness of 80nm provided by Shijiazhuangde mineral products Co.

The invention also provides a preparation method of the biomass filter membrane material for replacing the medical mask melt-blown cloth, which comprises the following specific steps:

(1) adding starch, polyvinyl alcohol, boric acid and nano tourmaline into a high-speed mixer, uniformly stirring at the temperature of 80-90 ℃, then adding sodium hydroxide into water to prepare an alkali liquor, then adding the alkali liquor into the high-speed mixer, closing an exhaust hole, continuously stirring for 15-25min to ensure that the alkali liquor fully permeates the starch and the polyvinyl alcohol, then heating the high-speed mixer to 110 ℃, simultaneously opening the exhaust hole to exhaust, reducing the moisture content of the materials, and then discharging to obtain a mixed material;

(2) and (3) sealing and storing the obtained mixed material, adding the sealed and stored material, EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder into a stirring kettle, uniformly mixing, extruding and foaming by using a single-screw extruder, longitudinally stretching a foamed sheet while the sheet is hot, air cooling and coiling to obtain the biomass filter membrane material for replacing medical mask melt-blown cloth.

Preferably, the moisture content of the material in step (1) is reduced to 10-12%.

Preferably, in the preparation of the mixed material in the step (1), the mass ratio of the starch, the polyvinyl alcohol, the boric acid, the nano tourmaline, the water and the sodium hydroxide is 20-30:3-5:0.02-0.05:0.1-0.2:10-15: 0.05-0.1.

Preferably, the sealing preservation method in the step (2) is to use paper to seal and preserve for 24-36 h.

Preferably, the single-screw extruder in the step (2) is a single-screw extruder with a short length-diameter ratio, the length-diameter ratio is controlled to be 10:1, and the extrusion die head is a die head with a gap of 1mm and a width of 200 mm.

More preferably, the single screw extruder having the short length to diameter ratio has a screw diameter of 4cm and a length of 40 cm.

Preferably, the stretching ratio of the longitudinal stretching in the step (2) is 3 to 5 times.

Preferably, in the preparation of the biomass filtering membrane material in the step (2), the mass ratio of the hermetically stored material, EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder is 80-90:3-5:1-2: 0.1-0.3.

It is known that SMS composite nonwoven fabrics are widely used in the fields of medical masks, air purification, and the like as functional nonwoven fabrics having excellent filtering functions. However, the preparation of the melt-blown fabric has high requirements on raw material processes, the control difficulty on the fineness and the uniformity of melt-blown fibers is high, and the melt-blown fabric is easy to stretch and deform when applied to a medical mask protective material. Through the analysis of the action mechanism of the melt-blown fabric, the main function is to prevent external foreign matters such as particles, dust, bacteria, viruses and the like from entering the human body through a respiratory tract. Therefore, as long as the design is reasonable to satisfy the high filterability and the collection and aggregation of the fine dust, the melt-blown cloth can be replaced.

According to the invention, the biomass material starch, polyvinyl alcohol, boric acid and nano tourmaline are added into a high-speed mixer, heated and stirred, then alkali liquor prepared from sodium hydroxide and water is added for permeation plasticizing treatment, and boric acid is utilized for crosslinking, so that the material has certain thermoplasticity, and the subsequent extrusion foaming material can be improved. The foaming polyvinyl alcohol contains a large amount of hydroxyl groups in molecules and has an open pore structure, high mechanical strength in a dry state, good flexibility in a wet state, good hand feeling and elasticity, and can still recover the flexibility after being dried and rewetted, and the foaming polyvinyl alcohol has the advantages of certain wear resistance, weather resistance, chemical stability, biocompatibility and the like, and is a good medical filter material. The starch is the main raw material of the starch polyvinyl alcohol, has the function of pore forming, and the foaming polyvinyl alcohol material with good water absorption, good pore structure and good flexibility is obtained by controlling the adding amount of the starch. The nano tourmaline powder is crushed from crystal tourmaline particles, has good electret with electrostatic adsorption function, and can make the foaming filter membrane material have lasting electret after being added, so that the foaming filter membrane material can adsorb fine particles and improve the filtering efficiency, and the nano tourmaline is used as a nucleating agent, so that the starch polyvinyl alcohol can be foamed to form uniform fine micropores.

Further, the mixed material is sealed and stored for more than 24 hours by using paper, so that the contained water is fully and uniformly permeated into the starch and the polyvinyl alcohol, and then the mixed material is mixed with EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder to be extruded and foamed. The purpose of adding EVA is to assist the plasticity of materials and enable the tensile property of products to be better, and the added N, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder not only enable the obtained filtering membrane material to have hydrophobicity and water resistance, but also have an electret effect and an adsorption effect on fine particles in filtering. The extrusion foaming process of the membrane material is carried out in a single screw extruder with a short length-diameter ratio, the length-diameter ratio of a screw is controlled to be 10:1, the typical selection is that the screw with the short length-diameter ratio is 4cm in diameter and 40cm in length, the added material is subjected to self-friction to generate heat rapidly and foam, and if the length-diameter ratio is too large, the material is excessively sheared and burnt to cause material blockage; if the length-diameter ratio is too low, the mixing uniformity is influenced, and the uniformity of the micropores of the obtained foaming filtering membrane is poor. And finally, the extruded and foamed thin sheet is longitudinally stretched, so that the micropore structure and uniformity are better, and the medical mask is convenient to manufacture.

The existing melt-blown cloth has high requirements on raw material technology, has high control difficulty on the fineness and the uniformity of melt-blown fibers, and is easy to stretch and deform when applied to a medical mask protective material, so that the application of the medical mask protective material is limited. In view of the above, the invention provides a biomass filter membrane material for replacing medical mask melt-blown cloth and a preparation method thereof, which comprises the steps of adding starch, polyvinyl alcohol, boric acid and nano tourmaline into a high-speed mixer, stirring uniformly, heating and stirring by the high-speed mixer; adding sodium hydroxide into water to prepare an alkali liquor, adding the alkali liquor into a high-speed mixer, closing an exhaust hole, and continuously stirring to enable the alkali liquor to fully permeate starch and polyvinyl alcohol; then heating the high-speed mixer, opening an exhaust hole, exhausting, reducing the moisture content of the material, then discharging, and sealing and storing the material; and (3) sealing and storing the obtained material, adding the material, EVA, N' -ethylene bis stearamide and polytetrafluoroethylene micro powder into a stirring kettle, uniformly mixing, extruding and foaming by a short-long extruder than a single-screw extruder, longitudinally stretching a foamed sheet while the foamed sheet is hot, air-cooling and coiling to obtain the biomass filter membrane material for replacing medical mask melt-blown cloth. The biomass filtering membrane material provided by the invention has high filtering efficiency, strong filtering, adsorbing and gathering properties on micro-fine dust and viruses, can completely replace the prior melt-blown cloth to be used for medical masks, and has the advantages of easily controllable and simple process, controllable micropores, extremely low equipment investment and wide application prospect.

Compared with the prior art, the invention provides a biomass filter membrane material for replacing medical mask melt-blown cloth and a preparation method thereof, and the outstanding characteristics and excellent effects are as follows:

1. the method for preparing the biomass filter membrane material has the advantages of easily controllable and simple process, controllable micropores and extremely low equipment investment, and solves the problems of high requirement on raw materials, complex production process and difficult quality control of the conventional melt-blown fabric.

2. The biomass filtering membrane material obtained by the invention has high filtering efficiency and strong filtering, adsorbing and gathering properties on micro-fine dust and viruses, and can completely replace the prior melt-blown cloth to be used for medical masks.

Drawings

FIG. 1: a high magnification of the biomass filter membrane obtained in example 1.

FIG. 2: high magnification of the biomass filter membrane material obtained in comparative example 1.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, but it should not be construed that the scope of the present invention is limited to the following examples. Various substitutions and alterations can be made by those skilled in the art and by conventional means without departing from the spirit of the method of the invention described above.