CN111691232B

CN111691232B - Paper-based filter material base paper for replacing mask melt-blown fabric and preparation method thereof

Info

Publication number: CN111691232B
Application number: CN202010566526.1A
Authority: CN
Inventors: 赵传山; 陈立栋; 李辉; 李杰华; 丁其军; 李霞
Original assignee: Shuxin Technology Co Ltd; Qilu University of Technology
Current assignee: Shuxin Technology Co Ltd; Qilu University of Technology
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-07-16
Anticipated expiration: 2040-06-19
Also published as: CN111691232A

Abstract

The invention relates to a base paper of a paper-based filter material for replacing mask melt-blown fabric and a preparation method thereof. The paper-based filter material base paper for replacing mask melt-blown fabric is characterized by comprising the following physical properties: the quantification is as follows: 20-40 g per square meter, and the tensile strength is as follows: 2 KN/m-4 KN/m; the wet strength is: 15% -30%; the bulk is 1.3-1.8 m³(ii)/g; the average pore diameter is: 30-55 μm; the respiratory resistance is: 30 Pa-170 Pa; surface potential after electret: 300V-600V, the particulate matter filtering efficiency is as follows: 50 to 80 percent. The invention adopts the plant fiber and the polylactic acid fiber as the filtering material for replacing the polypropylene melt-blown cloth for the first time, and adopts the negative ion fiber coating containing the nano fiber to solve the problems of large gaps and low filtering efficiency after the plant fiber and the polylactic acid fiber are formed into paper.

Description

Paper-based filter material base paper for replacing mask melt-blown fabric and preparation method thereof

Technical Field

The invention relates to a base paper of a paper-based filter material for replacing mask melt-blown cloth and a preparation method thereof, in particular to a preparation method of the base paper of the paper-based filter material for replacing the mask melt-blown cloth, which is prepared by taking plant fibers and polylactic acid fibers as materials and adopting a nano fiber and anion powder coating spraying technology, has low respiratory resistance, high filtration efficiency, high electret surface potential, environmental protection, degradability and low production cost, and belongs to the technical field of papermaking.

Background

China is a large industrial production country, and with the improvement of the living standard of people in China, the requirements of people on self health and environment are higher and higher. However, China is a developing big country and is in the industrialized stage of accelerated development, and the yield and consumption of steel, coal, cement, electric power and the like are in the forefront of the world. Due to the rapid development of the heavy industry, the energy industry and the raw material industry, the corresponding environmental pollution problem is more prominent, and the serious influence is brought to the physical and mental health of people. Airborne dust and bacteria are the two most serious pollutants, especially in public places, or poorly ventilated rooms (wards and institutional settings). Therefore, it is very important to wear the mask to reduce the harm of pollution to the body.

In 2020, the novel coronary pneumonia epidemic outbreak, in order to prevent the infection of novel coronavirus, the mask becomes the most important protective article, especially the disposable medical protective mask, plays an important role in blocking the transmission of virus. However, due to the severe epidemic situation, the mask is a shortage of materials in the whole country. The mask in China has the phenomenon of no value in the market. The melt-blown cloth is used as a key material of a filtering link of the disposable protective mask, and can be called as the heart of a medical surgical mask and an N95 mask. According to the report of people at the beginning, the supply of the melt-blown cloth is very tense due to the great increase of the demand of the mask during the epidemic situation, the price of the melt-blown cloth is also increased by the ship, and the price of the melt-blown cloth is difficult to be solved and the day price of the melt-blown cloth appears. The 'one cloth is difficult to demand' is reflected in that the supply of melt-blown cloth is not in demand and the spot goods are in shortage, so that the mask production is influenced; the 'one cloth day price' is reflected in that the melt-blown cloth is expanded from 2 ten thousand yuan per ton to 30 ten thousand to 40 ten thousand yuan per ton before epidemic situation, thereby not only increasing the production cost, but also improving the sale price of the mask.

The main raw material of the melt-blown fabric is polypropylene, which is a semi-crystalline thermoplastic plastic with high impact resistance, strong mechanical properties and resistance to corrosion of various organic solvents and acids and bases. Has wide application in the industry and is the most important raw material in the production of disposable protective masks. However, the melt-blown fabric has certain disadvantages, namely high production cost, small production capacity, difficult degradation and environmental pollution. According to statistics: the proportion of polypropylene in the waste plastic is about 18 percent. It can be seen that polypropylene in the waste plastics accounts for a considerable specific gravity. Before the epidemic situation occurs, the mask is used in a small amount, and the waste mask is mainly buried or randomly discarded in the natural environment along with other garbage. This not only wastes resources, but also causes great pollution to the environment. Due to the characteristics of the molecular structure of the polypropylene material, a large number of tertiary carbon atoms exist in a molecular chain, the atoms can be aged and degraded in different degrees under the action of light, oxygen and heat, short carbon chains are generated, and after being oxidized, the short carbon chains can release aldehyde and ketone volatile substances, so that the soil and the air are seriously polluted, and animals, plants and human beings are seriously injured.

In recent years, a wide range of novel mask filter materials have been studied, and particularly, a completely degradable filter material which is free of pollution and toxicity has become a research focus, among which a polylactic acid filter material and a plant fiber filter material are the most representative. Polylactic acid is a novel degradable biological material polymerized from lactic acid, and can be completely degraded into water and carbon dioxide. The plant fiber filtering material is prepared by taking plant fibers as raw materials and performing special treatment according to a specific papermaking process.

CN201610034279.4 discloses a filter paper for a PM2.5 protective mask and a preparation method thereof. The filter paper base material is mainly prepared from the following raw materials in parts by weight: 25-40 parts of tencel fiber, 20-35 parts of polyester fiber, 30-40 parts of calcium carbonate filler, 0.1-0.3 part of binary retention aid and 0.3-0.8 part of polyamide polyamine epoxy chloropropane resin. The method is characterized in that: the filter paper base material with high filling amount and compact structure is manufactured by papermaking, and is subjected to rewetting, then enters a super-grade calender, and then is subjected to dilute acid dipping treatment, water leaching deacidification, drying and shaping in sequence. The invention adopts wet forming and super press polishing technology to manufacture compact base material, and combines high filling and dilute acid processing technology to construct static submicron-grade aperture; meanwhile, the filler is used for regulating and controlling the pore size distribution and porosity of the filter paper, so that the regulation and control of the filter resistance are realized, and the requirements of high efficiency and low resistance of the filter paper for the PM2.5 protective mask are met.

CN201610428539.6 discloses a method for preparing hemp root bast filter paper for haze-proof mask, which comprises the steps of sequentially cutting, steaming, bleaching, defibering, pulping, making paper, squeezing and drying hemp root bast. The invention prepares the hemp root bast with relatively coarse and hard hemp root bast into the hemp root bast filter paper with better thickness, ration, aperture and porosity, thereby realizing the reutilization of the waste textile. The obtained hemp root bast filter paper pair is 0.26 μm and 15.6mg/m³The filtering efficiency of NaCl aerosol particles with the density of 2% and the concentration of 99.94% -100% is high, so that the air particle filtering device has good air particle filtering efficiency, can be applied to anti-haze masks, has a high-efficiency filtering effect, and has a wide market application prospect.

Chinese patent document CN 104289042A (application No. 201410452788.X) discloses an electrostatic spinning nanofiber electret filter material and a preparation method thereof, wherein the high-efficiency and low-resistance nanofiber electret filter material with a fluffy three-dimensional net-shaped intercommunicating structure and without adhesion among fibers is prepared by one-step forming through controlling the components and the temperature of a polymer solution and the forming 'quick cooling' process of nanofibers in the electrostatic spinning process. However, the electrostatic spinning has the limitations of small yield, poor physical and mechanical properties and the like, and the application of the obtained nanofiber material mainly focuses on the related fields of high added value, low dosage and high precision.

The technical proposal improves the filter paper on raw materials and preparation process, but still has the problems of insufficient filter effect and difficult degradation.

Chinese patent document CN104878646A (application No. 201510237571.1) discloses a high-precision air filter paper, which comprises base paper and an impregnant for impregnating the base paper, wherein the base paper comprises glass fiber, cotton linter pulp subjected to alkali treatment, polylactic acid fiber, a defoaming agent, a dispersing agent, a wet strength agent, a waterproof agent and a whitening agent, and the impregnant comprises phenolic resin, styrene-acrylic emulsion, N-hexane, methanol, N-methylol acrylamide and a wetting agent; the invention also discloses a preparation method of the high-precision air filter paper, and the high-precision air filter paper obtained by the preparation method has the characteristics of higher filtering precision, relatively lower filtering resistance, higher pollutant carrying capacity, long service life and good quality stability.

Although the technology makes full use of the characteristics of high porosity and small pore diameter after mixing the glass fiber and the polylactic acid fiber to prepare the air filter paper with high filtering precision, all indexes of the air filter paper are not suitable for replacing the mask flocked fabric, and especially, the pore diameter of the air filter paper is still large and can not reach the filtering index of the mask flocked fabric.

Chinese patent document CN108774912A (application No. 201810388997.0) discloses a preparation method of refreshing paper handkerchief, which comprises adding potassium permanganate into ethanol solution, stirring, standing, filtering to remove precipitate, adding activated carbon, filtering, and filtering the filtrate with silica gel to obtain purified ethanol; cleaning flos Rosae Rugosae, Ginseng radix, radix Rhodiolae, and radix Paeoniae, mashing, and placing in a steam generator to obtain mixed essential oil; adding neral and muscone into purified ethanol, sealing for 4-6 days, adding mixed essential oil, sealing and storing for 3-5 days, adding beta cyclodextrin into warm water, stirring to obtain saturated solution, adding mixed ethanol solution according to a ratio, heating and stirring for 1-2 h, naturally cooling to precipitate crystals, performing suction filtration, and drying at 50 ℃ for 2 h; adding the product into 10 wt% polylactic acid solution, obtaining composite polylactic acid fiber through electrostatic spinning, then pulping softwood pulp, cotton pulp, hardwood pulp and composite polylactic acid fiber, and obtaining the composite polylactic acid fiber through papermaking and rewinding. The preparation method of the paper handkerchief provided by the invention is simple to operate, low in cost, easy for large-scale production and good in application prospect. The paper handkerchief with the refreshing effect is prepared by mixing and pulping the composite polylactic acid fiber with softwood pulp, cotton pulp and hardwood pulp.

Disclosure of Invention

Aiming at the problems of low yield, high cost, environmental pollution, biological harm and the like of the polypropylene melt-blown fabric, the invention provides the manufacturing method of the base paper of the paper-based filter material which is simple to operate and low in cost and can replace the mask melt-blown fabric. The raw paper of the paper-based filter material, which is used for replacing mask melt-blown cloth, has the advantages of excellent quality, high electret voltage, low respiratory resistance, strong particulate matter filtering efficiency, environmental protection and no pollution, is prepared. Subsequently, the base paper of the paper-based filter material is subjected to special coating treatment and electret treatment, and then the paper-based filter material for the mask with the filter performance equivalent to that of polypropylene melt-blown fabric can be prepared.

The technical scheme of the invention is as follows:

the negative ion fiber coating comprises the following components in percentage by mass:

2 to 5 percent of anion powder, 0.01 to 0.05 percent of nano-fiber and the balance of water.

According to the invention, the particle size of the anion powder is preferably less than or equal to 30 μm.

The negative ion powder is a mixture of multiple minerals which can permanently release negative ions, and can excite atoms in the air to release electrons to form negative oxygen ions, thereby forming a negative ion field effect and a far infrared effect in a certain range.

Preferably according to the invention, the nanofibres are selected from plant fibres and/or bacterial cellulose; further preferably, the plant fiber is a softwood fiber and/or a hardwood fiber.

The nano-fiber can be prepared by a physical crushing method, a homogenizing method or a chemical method.

According to the invention, the diameter of the nanofiber is preferably 100-500 nm, and the length-diameter ratio is preferably 100-1000.

A preparation method of base paper of a paper-based filter material for replacing mask melt-blown fabric comprises the following steps:

(1) mixing polylactic acid fiber and beaten plant fiber in proportion, adding wet strength agent for papermaking, and dispersing uniformly to obtain slurry;

(2) diluting the slurry prepared in the step (1), and forming paper to prepare a wet paper web;

(3) and (3) spraying the negative ion fiber coating on the surface of the wet paper web prepared in the step (2), and then drying and performing subsequent paper forming treatment to prepare the base paper of the paper-based filter material for replacing mask melt-blown cloth.

According to the invention, in the step (1), the length of the polylactic acid fiber is 2-6 mm, and the diameter is 1-3 μm.

According to the invention, in the step (1), the polylactic acid fiber accounts for 20-40% of the total fiber mass.

The polylactic acid fiber is used as a high molecular organic fiber and can be electrostatically electret, so that paper generates lasting and effective static electricity, and generates an electrostatic adsorption effect, thereby improving the filtering efficiency.

Preferably, in the step (1), the plant fiber is softwood fiber, hardwood fiber or a mixed fiber of the softwood fiber and the hardwood fiber; the beating degree of the plant fiber is 20-40 DEG SR.

The beating degree is 20-40 degrees SR, so that the fibers can be subjected to moistening, the average pore diameter is reduced, and the filtering efficiency is improved.

Preferably, in the step (1), the plant fiber is bleached wood pulp prepared by chemical pulping or chemimechanical pulping.

According to the invention, in the step (1), the plant fiber accounts for 60-80% of the total fiber mass.

According to the invention, in the step (1), the wet strength agent for papermaking is chlorine-free polyamide polyamino epichlorohydrin; preferably, the wet strength agent for papermaking is used in an amount of 0.3 to 0.8 percent of the total fiber weight.

The polyamide polyamino epichlorohydrin can improve the wet strength of the paper and provides a foundation for subsequent coating processing.

According to the invention, in the step (2), the slurry is diluted to a mass concentration of 0.01-0.05%.

The single fiber of the sizing agent exists in the concentration range, so that the polylactic acid fiber can reach an ideal dispersion state, the uniformity of the prepared paper sheet is improved, and the filtering efficiency is improved.

According to the invention, in the step (2), the paper is formed by inclined wire forming.

The inclined wire forming mode is applied to the large-scale dehydration of the ultra-low concentration fiber pulp, and is beneficial to forming uniform paper sheets.

According to the invention, in the step (3), the spraying coating amount of the anionic fiber coating is preferably 2-4 g/square meter in terms of solid content. The solid is the general name of the anion powder and the nano-fiber.

The spraying of the anion fiber coating can further reduce the pore diameter and increase the filtering effect on the tiny particles; meanwhile, the negative ion powder in the negative ion fiber coating has the effect of permanently releasing negative ions to form an electrostatic field, and is matched with the polylactic acid fiber for use, so that the retention rate of charges after the polylactic acid fiber electret is enhanced, the attenuation speed is reduced, and the paper-based filter material base paper which is prepared by taking the polylactic acid electret as a material and replaces mask melt-blown cloth has long-time electrostatic voltage.

According to the invention, in the step (3), the anionic fiber coating is sprayed on the upper surface of the wet paper web. After the negative ion fiber coating is sprayed on the upper surface of the wet paper web, the negative ion fiber coating enables the nano fibers and the negative ion powder to be filled in fiber gaps under the action of gravity, so that the average pore diameter can be better reduced.

According to the invention, in the step (3), preferably, the drying and the subsequent paper forming treatment are carried out according to a production process of sanitary paper towels with the weight of 20-40 g per square meter.

The total fiber is a generic name of the polylactic acid fiber and the plant fiber in the step (1).

The paper-based filter material base paper for replacing mask melt-blown cloth has the following physical properties:

the quantification is as follows: 20-40 g per square meter, and the tensile strength is as follows: 2 KN/m-4 KN/m; the wet strength is: 15% -30%; the bulk is 1.3-1.8 m³(ii)/g; the average pore diameter is: 30-55 μm; the respiratory resistance is: 30 Pa-170 Pa; surface potential after electret: 300V-600V, the particulate matter filtering efficiency is as follows: 50 to 80 percent.

According to the invention, the paper-based filter material base paper for replacing mask meltblown fabric preferably has the following physical properties:

the quantification is as follows: 25-35 g per square meter, and the tensile strength is as follows: 2.5 KN/m-3.5 KN/m; the wet strength is: 15% -30%; the bulk is 1.4-1.7 m³(ii)/g; the average pore diameter is: 30-45 μm; the respiratory resistance is: 30 Pa-150 Pa; surface potential after electret: 350V-600V, and the particulate matter filtering efficiency is as follows: 55 to 80 percent.

A filter device comprises at least one layer of the base paper of the paper-based filter material as a filter part.

A mask comprises at least one layer of the paper-based filter material as a filter part.

Advantageous effects

1. According to the invention, the plant fiber and the polylactic acid fiber are used as the filtering material for replacing polypropylene melt-blown cloth for the first time, and the problem of large gaps and low filtering efficiency after the plant fiber and the polylactic acid fiber are formed into paper is solved by spraying the negative ion fiber coating containing the nanofiber; in addition, the negative ion powder in the negative ion fiber coating can release negative ions permanently to form an electrostatic field, so that the stability of the charge quantity of the polylactic acid fiber after being electret is protected, the potential attenuation of the paper-based filter material after being electret is reduced, the problem that the charge attenuation is too fast after the polylactic acid fiber is electret is solved, and the filtering efficiency is improved while higher surface potential is kept and the electrostatic adsorption capacity is improved.

2. According to the invention, polylactic acid fiber and plant fiber are used as raw materials, and the prepared base paper of the paper-based filter material can be completely degraded without polluting the environment; meanwhile, the base paper of the paper-based filter material has the advantages of rich raw materials, simple process, low cost and high yield.

3. The invention adopts the ultralow-concentration slurry and the inclined net forming process, improves the pore diameter uniformity of paper sheets, and ensures that the filtering efficiency is more uniform; and then, the paper sheets are sprayed by the anion fiber coating, so that the aperture of the base paper of the paper-based filter material is reduced, the porosity is improved, and the filtration efficiency is improved while the respiratory resistance is not changed.

Detailed description of the invention

The technical solution of the present invention is further described with reference to the following examples, but the scope of the present invention is not limited thereto.

In the embodiment, the polylactic acid short fiber is a common commercial product, the length is 2-4 mm, and the diameter is 1-2 um.

In the examples, softwood fibers and hardwood fibers are commonly available commercially and are available from Donhun group, Inc.

In the embodiment, the polyamide polyamino epichlorohydrin is a common commercial product, and the mass concentration of the product is 12.5%.

In the examples, the negative ion powder was available from Peng chemical industry Co., Ltd, Hebei province, and the diameter of the negative ion powder was 20 μm.

In the examples, the nanofibers are softwood nanofibers prepared by a TEMPO Cellulose oxidation method described in the patent of Determination of nanocellulose fiber length by laser sensitivity measurement (Tanaka et al, Cellulose 2014 6), and the nanofibers have a diameter of 200nm to 300nm and an aspect ratio of 300 to 600.

In the embodiment, the drying of the raw paper of the paper-based filter material and the subsequent paper forming treatment are carried out according to the drying of raw paper of sanitary paper towels with the square meter of 20 g/square meter to 40 g/square meter and the subsequent paper forming treatment process, which are the technologies commonly used in the field.

The measurement methods are based on the following national standards or test methods

Quantification: GB/T451.2-2002, a method for measuring the basis weight of paper and paperboard;

tensile strength: GB/T453-2002, determination of tensile strength of paper and paperboard;

wet strength: GB/T465.2-2008, determination of tensile strength of paper and paperboard after soaking in water;

bulk: GB/T451.3-2002 paper and paperboard thickness determination,

respiratory resistance: GB 2626-2019 respiratory protection self-priming filtration type particulate-proof respirator;

particulate matter filtration efficiency: GB 2626-2019 respiratory protection self-priming filtration type particulate-proof respirator;

average pore diameter: reference is made to the paper structure and performance study of polyimide/cellulose lithium battery separator paper (wangshisan, university of zilu industry, 2019);

surface potential after electret: reference is made to the paper "study of the electrical storage properties of porous polytetrafluoroethylene-polyethylene-polypropylene electrets" (Song Londong Hai, second university of military medical science 2006).

Example 1

A paper-based filter material base paper for replacing mask melt-blown fabric and a preparation method thereof comprise the following steps:

(1) mixing polylactic acid fiber accounting for 30 percent of the mass of the total fiber with softwood fiber accounting for 70 percent of the mass of the total fiber and having a beating degree of 30 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

(2) diluting the pulp prepared in the step (1) to the concentration of 0.025%, feeding the pulp into a paper machine, and forming paper by adopting an inclined wire forming mode to prepare a wet paper web;

(3) spraying the prepared negative ion fiber coating on the surface of the wet paper web prepared in the step (2), and spraying the upper surface, wherein the spraying amount is 3.5g/m in terms of solid matters²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel of 30 g/square meter.

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 1:

TABLE 1

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	3.05KN/m
		Wet strength	20％
Bulk thickness	1.5m³/g
		Average pore diameter	38μm
Resistance to breathing	46Pa
		Back surface potential of electret	433V
Particulate matter filtration efficiency	63％

Example 2

(1) mixing polylactic acid fiber accounting for 40 percent of the mass of the total fiber with softwood fiber accounting for 60 percent of the mass of the total fiber and having a beating degree of 30 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

(3) spraying the negative ion fiber coating prepared in the example 1 on the surface of the wet paper web prepared in the step (2), and spraying the upper surface, wherein the spraying amount is 3.5g/m in terms of solid matters²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel of 30 g/square meter.

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 2:

TABLE 2

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	3.3KN/m
		Wet strength	17％
Bulk thickness	1.52m³/g
		Average pore diameter	32μm
Resistance to breathing	45Pa
		Back surface potential of electret	528V
Particulate matter filtration efficiency	71％

Example 3

(1) mixing polylactic acid fiber accounting for 20 percent of the mass of the total fiber with softwood fiber accounting for 80 percent of the mass of the total fiber and having a beating degree of 30 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 3:

TABLE 3

Example 4

(1) mixing polylactic acid fiber accounting for 30 percent of the mass of the total fiber with softwood fiber accounting for 70 percent of the mass of the total fiber and having a beating degree of 20 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 4:

TABLE 4

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	2.82KN/m
		Wet strength	18％
Bulk thickness	1.61m³/g
		Average pore diameter	42μm
Resistance to breathing	36Pa
		Back surface potential of electret	436V
Particulate matter filtration efficiency	54％

Example 5

(1) mixing polylactic acid fiber accounting for 30 percent of the mass of the total fiber with softwood fiber accounting for 70 percent of the mass of the total fiber and having a beating degree of 40 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 5:

TABLE 5

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	3.72KN/m
		Wet strength	23％
Bulk thickness	1.36m³/g
		Average pore diameter	30μm
Resistance to breathing	72Pa
		Back surface potential of electret	401V
Particulate matter filtration efficiency	68％

Example 6

(1) mixing polylactic acid fiber accounting for 30 percent of the mass of the total fiber with softwood fiber accounting for 70 percent of the mass of the total fiber and having a beating degree of 30 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.8 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 6:

TABLE 6

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	3.26KN/m
		Wet strength	28％
Bulk thickness	1.53m³/g
		Average pore diameter	37μm
Resistance to breathing	48Pa
		Back surface potential of electret	439V
Particulate matter filtration efficiency	64.5％

Example 7

(2) diluting the pulp prepared in the step (1) to the concentration of 0.05%, feeding the pulp into a paper machine, and forming paper by adopting an inclined wire forming mode to prepare a wet paper web;

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 7:

TABLE 7

Example 8

(3) spraying an anion fiber coating on the surface of the wet paper web prepared in the step (2), wherein the anion fiber coating is as described in example 1, except that the mass concentration of the nano fibers is 0.05%, the mass concentration of the anion powder is 2%, and the spraying amount on the upper surface is 3.5g/m in terms of solid matters²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel of 30 g/square meter.

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 8:

TABLE 8

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	2.72KN/m
		Wet strength	20％
Bulk thickness	1.51m³/g
		Average pore diameter	43μm
Resistance to breathing	32Pa
		Back surface potential of electret	386V
Particulate matter filtration efficiency	55％

Example 9

(3) spraying an anion fiber coating on the surface of the wet paper web prepared in the step (2), wherein the anion fiber coating is as described in example 1, except that the mass concentration of the nano fibers is 0.5%, the mass concentration of the anion powder is 5%, spraying amount is 3.5g/m on the solid content basis, and spraying amount is 3.5g/m on the upper surface²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel of 30 g/square meter.

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 9:

TABLE 9

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	3.32KN/m
		Wet strength	23％
Bulk thickness	1.43m³/g
		Average pore diameter	30μm
Resistance to breathing	59Pa
		Back surface potential of electret	490V
Particulate matter filtration efficiency	70％

Example 10

(1) mixing polylactic acid fiber accounting for 30 percent of the mass of the total fiber with broadleaf wood fiber accounting for 70 percent of the mass of the total fiber and having a beating degree of 30 DEG SR, adding paper-making wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

The data of the indexes of the new base paper for paper-based filtering material prepared in the embodiment are shown in the following table 10:

watch 10

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	2.36KN/m
		Wet strength	16％
Bulk thickness	1.36m³/g
		Average pore diameter	28μm
Resistance to breathing	159Pa
		Back surface potential of electret	410V
Particulate matter filtration efficiency	71％

Example 11

(1) mixing polylactic acid fibers accounting for 30 percent of the mass of the total fibers, softwood fibers accounting for 50 percent of the mass of the total fibers and having a beating degree of 30 DEG SR, and hardwood fibers accounting for 20 percent of the mass of the total fibers and having a beating degree of 25 DEG SR, adding a papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.5 percent of the mass of the total fibers, and uniformly dispersing to prepare a slurry;

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 11:

TABLE 11

Example 12

(1) mixing polylactic acid fiber accounting for 20 percent of the mass of the total fiber, softwood fiber accounting for 50 percent of the mass of the total fiber and having a beating degree of 20 DEG SR, and hardwood fiber accounting for 30 percent of the mass of the total fiber and having a beating degree of 30 DEG SR, adding paper-making wet strength agent polyamide polyamino epoxy chloropropane accounting for 0.3 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

(2) diluting the pulp prepared in the step (1) to the concentration of 0.02%, feeding the pulp into a paper machine, and performing paper forming by adopting an inclined wire forming mode to prepare a wet paper web;

(3) spraying an anion fiber coating on the surface of the wet paper web prepared in the step (2), wherein the anion fiber coating is as described in example 1, except that the mass concentration of the nano fibers is 0.5%, the mass concentration of the anion powder is 2.5%, and the spraying amount is 2.5g/m in terms of solid content on the upper surface²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel with the weight of 20 g/square meter.

The data of the indexes of the new base paper for the paper-based filtering material prepared in the embodiment are shown in the following table 12:

TABLE 12

Index (I)	Data of
		Quantification of	20g/㎡
Tensile strength	2.06KN/m
		Wet strength	15％
Bulk thickness	1.33m³/g
		Average pore diameter	30μm
Resistance to breathing	165Pa
		Back surface potential of electret	308V
Particulate matter filtration efficiency	51％

Example 13

(1) mixing polylactic acid fiber accounting for 20 percent of the mass of the total fiber with softwood fiber accounting for 80 percent of the mass of the total fiber and having a beating degree of 20 DEG SR, adding papermaking wet strength agent polyamide polyamino epichlorohydrin accounting for 0.8 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

(2) diluting the pulp prepared in the step (1) to the concentration of 0.01%, feeding the pulp into a paper machine, and performing paper forming by adopting an inclined wire forming mode to prepare a wet paper web;

(3) spraying an anion fiber coating on the surface of the wet paper web prepared in the step (2), wherein the anion fiber coating is as described in example 1, and the difference is that the mass concentration of the nano fibers is 0.5%, and the mass concentration of the anion powder is2 percent of water is sprayed on the upper surface, and the spraying amount is 3g/m in terms of solid²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel of 30 g/square meter.

The indexes of the paper base filtering new material base paper prepared by the embodiment are as follows in the following table 13:

watch 13

Index (I)	Data of
		Quantification of	30g/㎡
Tensile strength	3.48KN/m
		Wet strength	30％
Bulk thickness	1.56m³/g
		Average pore diameter	41μm
Resistance to breathing	35Pa
		Back surface potential of electret	350V
Particulate matter filtration efficiency	52％

Example 14

(1) mixing polylactic acid fiber accounting for 40 percent of the mass of the total fiber, softwood fiber accounting for 60 percent of the mass of the total fiber and having a beating degree of 25 DEG SR, and hardwood fiber accounting for 10 percent of the mass of the total fiber and having a beating degree of 40 DEG SR, adding paper-making wet strength agent polyamide polyamino epoxy chloropropane accounting for 0.5 percent of the mass of the total fiber, and uniformly dispersing to prepare slurry;

(3) spraying an anion fiber coating on the surface of the wet paper web prepared in the step (2), wherein the anion fiber coating is as described in example 1, except that the mass concentration of the nano fibers is 0.5%, the mass concentration of the anion powder is 5%, spraying amount is 4g/m in terms of solid matter on the upper surface²And then preparing the raw paper of the paper-based filter material for replacing mask melt-blown fabric according to a drying process and a subsequent paper forming process of the raw paper of the sanitary paper towel of 40 g/square meter.

The data of the indexes of the new base paper for paper-based filtering material prepared in the embodiment are shown in the following table 14:

TABLE 14

Index (I)	Data of
		Quantification of	40g/㎡
Tensile strength	3.69KN/m
		Wet strength	16％
Bulk thickness	1.42m³/g
		Average pore diameter	33μm
Resistance to breathing	146Pa
		Back surface potential of electret	568V
Particulate matter filtration efficiency	76％

Analysis of results

The paper-based filter material base paper prepared by the optimized scheme of the embodiment 1 has balanced various properties and good comprehensive performance, wherein various indexes such as tensile strength, wet strength, bulk, average pore diameter, breathing resistance, electret rear surface potential, 85L air flow NaCl aerogel filtering efficiency and the like can be compatible with one another, so that various indexes are optimized.

Example 2, example 3 is to change the weight ratio of polylactic acid fiber and softwood fiber. When the using amount of the polylactic acid short fiber is increased, the using amount of the softwood fiber is reduced, so that the surface potential is greatly improved after electret, and the filtering efficiency of particulate matters is improved; when the consumption of the short polylactic acid fibers is reduced, the consumption of the softwood fibers is increased, so that the surface potential is reduced after electret treatment, and the filtering efficiency of particles is reduced; while the other properties of the paper are substantially unchanged.

Example 4, example 5 to change the freeness of softwood fibers, when the freeness is reduced, the tensile strength is reduced, the bulk is increased, the average pore size is increased, and the respiratory resistance is reduced at the same time, but the particulate matter filtration efficiency is reduced; when the beating degree is improved, all indexes are just opposite, and the average pore diameter is reduced, so that when the electret voltage is reduced, the particulate matter filtering efficiency is improved.

Example 6 in order to increase the amount of the polyamide polyamine epichlorohydrin used as the wet strength agent for papermaking, the wet strength of paper is obviously improved, and other physical indexes are not changed greatly. The papermaking wet strength agent mainly improves the wet strength of the base paper and provides basic conditions for preparing a nano paper-based filter material with performance capable of replacing polypropylene melt-blown fabric through subsequent coating processing.

Example 7 in order to change the concentration of the pulp on the wire, the fibers exist as single free fibers at a concentration of 0.05%, the dispersion and the paper forming uniformity are good for the production of the paper base collected material containing chemical fibers, and the physical properties of the paper are not greatly influenced in the concentration range of the pulp on the wire.

Example 8, example 9 was conducted to change the concentration of the nanofiber and anion powder mixed coating, so that the average pore size, the breathing resistance, the surface potential after electret and the particulate matter filtering efficiency of the paper were changed. The nano fiber can better improve the pore diameter of paper, the average pore diameter is reduced when the amount of the nano fiber is increased, the respiratory resistance is improved, and meanwhile, the filtering efficiency is also improved. The anion powder can reduce the charge attenuation speed of the polylactic acid fiber after electret and increase the surface potential storage time after the electret, thereby solving the problem of low filtration efficiency caused by fast charge attenuation of polylactic acid fiber electret materials.

Example 10, example 11 to change the type of plant fiber, a base paper for paper-based filter material was prepared, which had decreased tensile strength, wet strength, bulk, and mean pore size, increased breathing resistance, and increased particle filtration efficiency, but did not change the electret surface potential much, when the plant fibers were hardwood fibers. When the softwood and the hardwood are mixed, various performances of the base paper of the paper-based filter material are basically between performance indexes of the full softwood fiber base paper and the full hardwood fiber base paper, but the respiratory resistance is still higher. Proved that the hardwood fibers can be used for preparing the base paper of the paper-based filter material, but the hardwood fibers have small diameter and short fiber, so that the bulk of the paper is low, the average pore diameter is low, and the respiratory resistance is higher in the national standard range.

In example 12, example 13 and example 14, the raw paper for paper-based filter materials of 20 g/square meter, 30 g/square meter and 40 g/square meter was prepared according to different variable schemes, and each physical index group of the raw paper for paper-based filter materials meets the requirements, and the tensile strength and the filtration efficiency of the raw paper for high-quantification paper-based filter materials are higher, but the respiratory resistance is also improved, and the average pore size is reduced. Because air filtration efficiency and respiratory resistance are contradictory physical indicators, different processes and different amounts of paper have different effects on the air filtration efficiency and respiratory resistance.

Comparative example 1

Compared with the embodiment 1, the difference is that the polylactic acid short fiber is not added in the step (1), and other processes are the same.

The indexes of the base paper of the new material for paper-based filtration prepared by the comparative example are as follows in the following table 15:

watch 15

Analysis of results

The polylactic acid short fibers are not added in the comparative example 1, so that the electrostatic voltage is 0V after electret, the electrostatic adsorption effect is greatly reduced, the filtering efficiency of the base paper of the paper-based filtering material is low, and the polylactic acid short fibers can improve the electrostatic effect of the base paper of the paper-based filtering material, so that the filtering efficiency is improved.

Comparative example 2

Compared with the example 1, the difference is that no softwood fiber is added in the step (1), and other processes are the same.

The indexes of the base paper of the new material for paper-based filtration prepared by the comparative example are as follows in the following table 16:

TABLE 16

Index (I)	Data requirements	Comparative example 2	Example 1
				Quantification of	20g/㎡～40g/㎡	30g/㎡	30g/㎡
Tensile strength	2KN/m～4KN/m	0.35KN/m	3.05KN/m
				Wet strength	15％～30％	0.3％	20％
Bulk thickness	1.3～1.8m³/g	1.73m³/g	1.5m³/g
				Average pore diameter	30μm～55μm	68μm	38μm
Resistance to breathing	30Pa～170Pa	3.6Pa	46Pa
				Back surface potential of electret	300V～600V	926V	433V
Particulate matter filtration efficiency	50％～80％	13％	63％

Analysis of results

In comparative example 2, the softwood fiber is not added, the strength of the paper made of the pure polylactic acid fiber is too low, the wet strength is reduced, the average pore size is improved, the respiratory resistance is reduced, the surface potential is improved after electret, but the filtering efficiency is reduced to 0 percent, because the plant fiber is not used for improving the strength, and the gaps are not filled, so that the polylactic acid fiber is easy to damage in use and test after the paper is made, and the fact that the plant fiber can improve the strength of the paper made, reduce the average pore size and improve the filtering efficiency is proved.

Comparative example 3

Compared with the example 1, the difference is that the polyamide polyamino epichlorohydrin is not added in the step (1), and other processes are the same.

The indexes of the base paper of the new material for paper base filtration prepared by the comparative example are as follows in the following table 17:

TABLE 17

Index (I)	Data requirements	Comparative example 2	Example 1
				Quantification of	20g/㎡～40g/㎡	30g/㎡	30g/㎡
Tensile strength	2KN/m～4KN/m	0.32KN/m	3.05KN/m
				Wet strength	15％～30％	0.2％	20％
Bulk thickness	1.3～1.8m³/g	1.51m³/g	1.5m³/g
				Average pore diameter	30μm～55μm	39μm	38μm
Resistance to breathing	30Pa～170Pa	47Pa	46Pa
				Back surface potential of electret	300V～600V	435V	433V
Particulate matter filtration efficiency	50％～80％	62％	63％

Analysis of results

In the comparative example 3, polyamide polyamino epichlorohydrin is not added, so that the wet strength of the base paper of the paper-based filter material is reduced to 0.2%, almost no wet strength exists, and sufficient wet strength cannot be provided for subsequent processing. The polyamide polyamino epichlorohydrin is proved to be capable of effectively improving the wet strength of the base paper.

Comparative example 4

Compared to example 1. The difference is that in the step (2), the fiber pulp is not made into an ultra-low concentration and inclined wire forming mode, and when the concentration is more than the critical concentration (0.05%), a rotary wire forming mode is adopted for papermaking, and other processes are the same.

The indexes of the base paper of the new material for paper base filtration prepared by the comparative example are as follows 18:

watch 18

Analysis of results

In comparative example 4, the base paper of the paper-based filter material is prepared without the fiber pulp in an ultra-low concentration and inclined net forming mode, so that the average pore size is increased, the respiratory resistance is reduced, and the particulate matter filtering efficiency is reduced, because the polylactic acid fiber of the pulp with larger concentration is not uniformly dispersed, the paper formation uniformity is poor, and the average pore size and the filtering efficiency are influenced.

Comparative example 5

Compared with the example 1, the difference is that the nano-fiber spraying is not carried out in the step (3), only the negative oxygen ion exciting agent is sprayed, and other processes are the same.

The indexes of the base paper of the new material for paper base filtration prepared by the comparative example are as follows 19:

watch 19

Index (I)	Data requirements	Comparative example 2	Example 1
				Quantification of	20g/㎡～40g/㎡	30g/㎡	30g/㎡
Tensile strength	2KN/m～4KN/m	2.46KN/m	3.05KN/m
				Wet strength	15％～30％	18％	20％
Bulk thickness	1.3～1.8m³/g	1.52m³/g	1.5m³/g
				Average pore diameter	30μm～55μm	63μm	38μm
Resistance to breathing	30Pa～170Pa	16Pa	46Pa
				Back surface potential of electret	300V～600V	429V	433V
Particulate matter filtration efficiency	50％～80％	25％	63％

Analysis of results

In the comparative example 5, the nano-fiber is not sprayed, so that the average pore diameter of the base paper of the paper-based filter material is improved to 63 mu m, the air filtration efficiency is reduced to 25 percent, and the tensile strength is also reduced. The spraying of the nano-fiber is proved to effectively reduce the average pore diameter of the material, improve the air filtration efficiency and simultaneously improve the tensile strength of the finished paper.

Comparative example 6

Compared with the embodiment 1, the difference is that only the nano-fiber spraying is carried out in the step (3), the negative oxygen ion exciting agent is not sprayed, and other processes are the same.

The indexes of the base paper of the new material for paper base filtration prepared by the comparative example are as follows 20:

watch 20

Index (I)	Data requirements	Comparative example 2	Example 1
				Quantification of	20g/㎡～40g/㎡	30g/㎡	30g/㎡
Tensile strength	2KN/m～4KN/m	3.10KN/m	3.05KN/m
				Wet strength	15％～30％	19％	20％
Bulk thickness	1.3～1.8m³/g	1.49m³/g	1.5m³/g
				Average pore diameter	30μm～55μm	42μm	38μm
Resistance to breathing	30Pa～170Pa	45Pa	46Pa
				Back surface potential of electret	300V～600V	256V	433V
Particulate matter filtration efficiency	50％～80％	43％	63％

Analysis of results

In the comparative example 6, negative ion powder is not sprayed, so that the surface potential of the paper is quickly attenuated after electret, the electrostatic adsorption effect is weakened, and the particulate matter filtering efficiency is reduced. The negative ion powder is proved to be capable of maintaining the attenuation of charges after the polylactic acid fiber is electret, increasing the electrostatic adsorption effect and improving the filtering efficiency of particles.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the embodiments, and any other changes, modifications, combinations, substitutions and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.

Claims

1. A preparation method of base paper of a paper-based filter material for replacing mask melt-blown fabric is characterized by comprising the following steps:

(3) spraying an anion fiber coating on the surface of the wet paper web prepared in the step (2), and then drying and performing subsequent paper-forming treatment to prepare raw paper of the paper-based filter material for replacing mask melt-blown fabric;

the anion fiber coating comprises the following components in percentage by mass:

2. The method according to claim 1, wherein in the step (1), the polylactic acid fiber has a length of 2 to 6mm and a diameter of 1 to 3 μm.

3. The method according to claim 1, wherein in the step (1), the polylactic acid fiber accounts for 20-40% of the total fiber mass.

4. The method of claim 1, wherein in the step (1), the plant fiber is softwood fiber, hardwood fiber, or a mixture of softwood fiber and hardwood fiber; the beating degree of the plant fiber is 20-40 DEG SR.

5. The method of claim 1, wherein the vegetable fiber is bleached wood pulp obtained by chemical pulping or chemi-mechanical pulping in the step (1).

6. The method according to claim 1, wherein the plant fiber accounts for 60 to 80% of the total fiber mass in the step (1).

7. The method according to claim 1, wherein in the step (1), the wet strength agent for papermaking is a chlorine-free polyamide-polyaminoepichlorohydrin.

8. The method of claim 1, wherein in step (1), the wet strength agent is used in an amount of 0.3 to 0.8% by weight of the total fiber.

9. The method according to claim 1, wherein in the step (2), the slurry is diluted to a mass concentration of 0.01 to 0.05%.

10. The method of claim 1, wherein in the step (2), the paper is formed by oblique wire forming.

11. The method according to claim 1, wherein in step (3), the spray application amount of the anionic fiber coating is 2 to 4g per square meter in terms of solid content.

12. The method of claim 1, wherein in the step (3), the anionic fiber coating is sprayed on the upper surface of the wet paper web.

13. The method of claim 1, wherein in step (3), the drying and subsequent sheet formation is performed according to a process for producing sanitary paper towels having a weight of 20 to 40 grams per square meter.

14. The method according to claim 1, wherein the particle size of the negative ion powder in the step (3) is 30 μm or less.

15. The method according to claim 1, wherein the nanofibers in step (3) are selected from plant fibers and/or bacterial cellulose.

16. The method of claim 15, wherein the plant fiber is softwood fiber and/or hardwood fiber.

17. The method according to claim 1, wherein the diameter of the nanofibers in step (3) is 100 to 500nm, and the aspect ratio is 100 to 1000.

18. The paper-based filter material base paper for replacing mask melt-blown fabric is characterized by comprising the following physical properties:

19. The paper-based filter stock of claim 18, wherein the physical properties of the paper-based filter stock replacing mask meltblown fabric are as follows:

20. A filter device, characterized in that it comprises at least one layer of the base paper of paper-based filter material produced by the production method according to any one of claims 1 to 17 or the base paper of paper-based filter material according to any one of claims 18 to 19 as a filter part.

21. A mask comprising at least one layer of the base paper of the paper-based filter material prepared by the preparation method according to any one of claims 1 to 17 or the base paper of the paper-based filter material according to any one of claims 18 to 19 as a filter part.