CN117144557A - Preparation method and application of polylactic acid electret melt-blown non-woven fabric - Google Patents

Preparation method and application of polylactic acid electret melt-blown non-woven fabric Download PDF

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Publication number
CN117144557A
CN117144557A CN202310949192.XA CN202310949192A CN117144557A CN 117144557 A CN117144557 A CN 117144557A CN 202310949192 A CN202310949192 A CN 202310949192A CN 117144557 A CN117144557 A CN 117144557A
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China
Prior art keywords
melt
polylactic acid
electret
blown
woven fabric
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王先锋
张迪安
丁彬
俞建勇
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Donghua University
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Donghua University
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    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4326—Condensation or reaction polymers
    • D04H1/435—Polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/08—Filter cloth, i.e. woven, knitted or interlaced material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/0001—Making filtering elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/10—Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
    • B01D46/12—Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces in multiple arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/0004—Cutting, tearing or severing, e.g. bursting; Cutter details
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • B32B5/265—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary characterised by one fibrous or filamentary layer being a non-woven fabric layer
    • B32B5/266—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary characterised by one fibrous or filamentary layer being a non-woven fabric layer next to one or more non-woven fabric layers
    • B32B5/268—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary characterised by one fibrous or filamentary layer being a non-woven fabric layer next to one or more non-woven fabric layers characterised by at least one non-woven fabric layer that is a melt-blown fabric
    • B32B5/269—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary characterised by one fibrous or filamentary layer being a non-woven fabric layer next to one or more non-woven fabric layers characterised by at least one non-woven fabric layer that is a melt-blown fabric characterised by at least one non-woven fabric layer that is a melt-blown fabric next to a non-woven fabric layer that is a spunbonded fabric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/08—Melt spinning methods
    • D01D5/098—Melt spinning methods with simultaneous stretching
    • D01D5/0985—Melt spinning methods with simultaneous stretching by means of a flowing gas (e.g. melt-blowing)
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/92—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyesters
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/56—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving in association with fibre formation, e.g. immediately following extrusion of staple fibres
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06B—TREATING TEXTILE MATERIALS USING LIQUIDS, GASES OR VAPOURS
    • D06B1/00—Applying liquids, gases or vapours onto textile materials to effect treatment, e.g. washing, dyeing, bleaching, sizing or impregnating
    • D06B1/02—Applying liquids, gases or vapours onto textile materials to effect treatment, e.g. washing, dyeing, bleaching, sizing or impregnating by spraying or projecting
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06B—TREATING TEXTILE MATERIALS USING LIQUIDS, GASES OR VAPOURS
    • D06B15/00—Removing liquids, gases or vapours from textile materials in association with treatment of the materials by liquids, gases or vapours
    • D06B15/04—Removing liquids, gases or vapours from textile materials in association with treatment of the materials by liquids, gases or vapours by suction
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06B—TREATING TEXTILE MATERIALS USING LIQUIDS, GASES OR VAPOURS
    • D06B23/00—Component parts, details, or accessories of apparatus or machines, specially adapted for the treating of textile materials, not restricted to a particular kind of apparatus, provided for in groups D06B1/00 - D06B21/00
    • D06B23/04—Carriers or supports for textile materials to be treated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B01D2239/0668—The layers being joined by heat or melt-bonding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/10—Filtering material manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/20—All layers being fibrous or filamentary
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B32B2262/0276—Polyester fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/716—Degradable
    • B32B2307/7163—Biodegradable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/724—Permeability to gases, adsorption

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Filtering Materials (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)

Abstract

The application relates to a preparation method and application of polylactic acid electret melt-blown non-woven fabric, and the preparation method comprises the following steps: carrying out water electret treatment on the polylactic acid melt-blown non-woven fabric containing nano silicon nitride to prepare the polylactic acid electret melt-blown non-woven fabric; the content of nano silicon nitride in the prepared polylactic acid melt-blown non-woven fabric is 0.1-1 wt%; under the flow rate of 32L/min, the filtration efficiency of the polylactic acid electret melt-blown non-woven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.81% -99.98%, which is higher than that of a comparison sample by more than 12.8%, and the comparison sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown non-woven fabric without nano silicon nitride; application: polylactic acid electret meltblown nonwoven fabrics are used to make degradable water electret meltblown air filters. The nano silicon nitride is added to remarkably improve the filtration performance of the polylactic acid melt-blown non-woven fabric; the degradable water-resident melt-blown air filter prepared by the application adopts the bio-based polylactic acid as the raw material, and is environment-friendly.

Description

Preparation method and application of polylactic acid electret melt-blown non-woven fabric
Technical Field
The application belongs to the technical field of melt-blown non-woven fabrics, and relates to a preparation method and application of polylactic acid electret melt-blown non-woven fabrics.
Background
The air filtering material on the market is mainly made of petroleum-based polypropylene (PP) and is difficult to degrade under natural conditions. Therefore, there is a need to develop green, environmentally friendly, biodegradable air filtration materials. Polylactic acid (PLA) is prepared from starch such as corn, wheat, potato and the like as raw materials, and can be decomposed into carbon dioxide and water under the action of microorganisms in soil and seawater after being abandoned, so that the natural circulation of zero emission is realized, and the polylactic acid is an environment-friendly new material.
The existing melt-blown material generally adopts an electrostatic electret method (namely a corona electret technology), the voltage used by an electrostatic electret is as high as tens of kilovolts, the danger coefficient in the electret process is high, a large amount of ozone generated after oxygen ionization damages the environment, and charges can only be deposited on the surface of the melt-blown cloth after the electrostatic electret treatment, are easily influenced by the environmental temperature and humidity to dissipate, have poor transverse uniformity of charge density, seriously influence the service life of products, and cannot meet the long-term stable filtering requirement of the market on air filtering materials.
In order to solve the above problems, document 1 (Polylactic Acid/Calcium Stearate Hydrocharging Melt-Blown Nonwoven Fabrics for Respirator Applications, ACS Applied Polymer Materials, 2023.4.21) provides a technique of adding calcium stearate to Polylactic Acid melt-blown cloth and then performing water residence treatment, and the obtained product has a long service life but the filtration efficiency is still to be improved.
However, with the development of the society, the requirements of people on the filtering effect are higher and higher.
Therefore, research on a preparation method and application of the polylactic acid electret melt-blown non-woven fabric with higher filtration efficiency has very important significance.
Disclosure of Invention
The application aims to solve the problems in the prior art and provides a preparation method and application of polylactic acid electret melt-blown non-woven fabric.
In order to achieve the above purpose, the application adopts the following technical scheme:
the preparation method of the polylactic acid electret melt-blown non-woven fabric comprises the steps of carrying out water electret treatment on the polylactic acid melt-blown non-woven fabric containing nano silicon nitride to prepare the polylactic acid electret melt-blown non-woven fabric;
the content of nano silicon nitride in the polylactic acid melt-blown nonwoven fabric is 0.1-1 wt%; the filtration performance is not obviously improved if the content of the nano silicon nitride is too low, and the melt-blown spinning quality is affected if the content is too high;
the polylactic acid melt-blown nonwoven fabric with high filtration efficiency has the filtration efficiency of 99.81-99.98% on sodium chloride particles with the average diameter of 0.3 mu m, which is higher than that of a comparative sample by 12.8% or more, and the filtration efficiency of 98.64-99.05% on sodium chloride particles with the average diameter of 0.3 mu m, which is higher than that of the comparative sample by 19.73% or more, which is prepared by carrying out water residence treatment on the polylactic acid melt-blown nonwoven fabric without nano silicon nitride.
As a preferable technical scheme:
the polylactic acid electret melt-blown non-woven fabric containing the nano silicon nitride is prepared by a melt-blowing process of the dried levorotatory polylactic acid and melt-blown electret master batch;
the melt-blown electret master batch is obtained by uniformly mixing nano silicon nitride and dried L-polylactic acid according to the mass ratio of 1:4-9, then melt-extruding, and then water-cooling and granulating; the melt index of the L-polylactic acid is more than 30g/10min under the conditions of 230 ℃ and 2.16kg pressure.
The preparation of the electret master batch is to ensure that the nano silicon nitride is more uniformly mixed with the polylactic acid melt-blown raw material in the melt-blowing process so as to prevent the phenomena of hole blockage, uneven distribution of the nano silicon nitride among fibers and the like. Because nano silicon nitride is nano particle, and the melt-blown polylactic acid raw material is the circular granule of millimeter grade size, if directly mix nano silicon nitride particle and melt-blown polylactic acid raw material and melt-blow, both do not possess the cohesiveness, can't combine closely, especially in the toper feeder hopper, a large amount of nano silicon nitride particles can deposit down in advance in feed inlet department, cause the large amount of stack of nano silicon nitride particles in the melt-blowing process, the nano particle that gathers will cause the crooked, filter screen jam of screw rod, spinneret problem such as hole blocking, seriously influence equipment life, destroy the melt-blown fiber appearance. Therefore, the nano silicon nitride and the polylactic acid raw materials are prepared into the melt-blown electret master batch, the electret master batch is also round particles, the size of the electret master batch is equal to that of the polylactic acid melt-blown raw materials, the nano silicon nitride and the polylactic acid melt-blown raw materials can be well and uniformly mixed before melt blowing, the nano silicon nitride is uniformly distributed in the melt-blown polylactic acid fibers, and the melt-blown non-woven fabric with the best filtering performance is obtained.
According to the preparation method of the polylactic acid electret melt-blown non-woven fabric, the water content of the dried L-polylactic acid is less than 0.005%.
The preparation method of the polylactic acid electret melt-blown non-woven fabric comprises the following melt-blown process parameters:
the temperature of the first to the fifth areas of the screw extruder is 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and the die head temperature is 230-240 ℃ respectively;
the frequency of the metering pump is 16-20 Hz;
the temperature of hot air is 245-255 ℃, and the pressure of hot air is 0.15-0.28 MPa;
the receiving distance is 18-26 cm, and the frequency of the net conveying curtain is 6-8 Hz.
The preparation method of the polylactic acid electret melt-blown nonwoven fabric comprises the following process parameters of a double-screw extruder: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die temperature 190 ℃, the main machine rotating speed of 12rpm, the feeding speed of 10rpm, the water cooling is the circulating tap water, and the granulating speed of 12rpm.
The preparation method of the polylactic acid electret melt-blown non-woven fabric comprises the following steps of: pure water with the resistivity of 18.2MΩ & cm after purification is sprayed out from the fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 2-4 MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 1-3 Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene copolymer) material compression rollers in two pairs and outlets in a hot air drying system with the temperature of 45-55 ℃ carry out friction on the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid melt-blown non-woven fabric is obtained after drying.
The preparation method of the polylactic acid electret melt-blown non-woven fabric comprises the step of forming 3-7N extrusion force between 4 upper rods and 4 lower rods in a pair of compression rollers.
The application also provides a preparation method of the degradable water electret melt-blown air filter, which comprises the steps of cutting the degradable water electret air filter nonwoven fabric according to a certain width, and packaging the cut nonwoven fabric by an automatic folding machine to obtain the degradable water electret melt-blown air filter;
the degradable water electret air filtering nonwoven fabric is of a sandwich structure, and is obtained by carrying out ultrasonic thermal bonding on two layers of polylactic acid spunbonded nonwoven fabrics and the polylactic acid electret melt-blown nonwoven fabric prepared by adopting any one of the methods; the middle layer of the degradable water electret air filtering nonwoven fabric is polylactic acid electret melt-blown nonwoven fabric, provides filtering effect, the upper layer and the lower layer are polylactic acid spunbonded nonwoven fabric, and the upper layer and the lower layer only provide mechanical supporting effect.
As a preferable technical scheme:
the preparation method of the degradable water-resident melt-blown air filter comprises the following steps of: melting and extruding the dried high-melt-index dextrorotatory polylactic acid through a screw extruder, wherein the temperature of a 1-5 region of the screw extruder is 195 ℃, 2105, 220 ℃, 225 ℃, 230 ℃, the temperature of a die head is 230 ℃, the temperature of a liquid box is 260 ℃, and spinning holes are used for spraying spun-bonded filaments with certain fineness, and the polylactic acid spun-bonded non-woven fabric is formed on a net conveying curtain through high-speed negative pressure air draft of 0.5MPa and air flow yarn separation; the melt index of the high-melting-point dextrorotatory polylactic acid is more than 30g/10min under the conditions of 230 ℃ and 2.16kg pressure. The mechanism of the application is as follows:
document 2 (Single-Side Superhydrophobicity in Si) 3 N 4 -Doped and SiO 2 The nano silicon nitride in polymers 2022,14 (14), 2952 has negative effect on the filtration performance of polypropylene melt-blown nonwoven because as the nano silicon nitride content increases, the nonwoven fibers become thicker, resulting in an increase in the pore size of the material and eventually a decrease in the filtration performance. Unlike available technology, the present application has nanometer silicon nitride added to raise the filtering performance of polylactic acid melt blown non-woven fabric.
In document 2, a great amount of surface charge and near surface charge are applied to a polypropylene melt-blown fabric by using a corona electret technique, charge traps are shallow, and the charge amount is unsaturated, so that the positive effect of adding nano silicon nitride to increase the charge amount of the melt-blown fabric cannot offset the negative effect of thickening fibers on filtration performance, and further the filtration performance of the melt-blown nonwoven fabric is reduced, and in document 2, the nano silicon nitride is added to the polypropylene melt-blown fabric, not for improving the filtration efficiency of the melt-blown fabric, but for imparting good antibacterial performance to the polypropylene melt-blown fabric. The polylactic acid water-based electret melt-blown non-woven fabric containing the nano silicon nitride prepared by the application has the advantages that although the fiber diameter is increased due to the addition of the nano silicon nitride, the filtration performance of the polylactic acid melt-blown non-woven fabric is obviously improved due to the addition of the nano silicon nitride. The method is characterized in that water electret treatment brings a large amount of deep trap charges to polylactic acid melt-blown non-woven fabric, saturation of charge quantity and increase of deep trap charge quantity greatly improve the effect of nano silicon nitride capture charges in melt-blown fibers, nano silicon nitride with large forbidden band width can generate an additional potential field after being added into polylactic acid, meanwhile, the original periodic potential field of crystals is changed, holes can be bound around the holes to generate localized electron states, so that more trap energy levels are introduced in the forbidden band, in addition, the specific surface area of nano silicon nitride is large, the density of dangling bonds and oxygen vacancies of the deep traps is greatly improved, more deep hole traps are provided for the polylactic acid, and the gain of capturing more deep trap charges to the filtering performance is far greater than the damage to the filtering performance caused by the increase of fiber diameter by the melt-blown non-woven fabric.
Polylactic acid rubs with water to lose electrons to generate a large number of hole traps, while polypropylene obtains electrons in the water electret process to form a large number of electron traps. According to the state density theory of condensed state physics, electret surface charges and bulk charges are stored in trap energy levels of band gaps between a conduction band and a valence band, wherein the conduction band energy is higher than the valence band, electrons near the bottom of the conduction band move between extended states, and the electret surface charges and bulk charges have quite large mobility without thermal excitation of external environment and are easy to escape. It is known from the polymer band distribution that the energy level of the electron trap closer to the conduction band is higher than that of the hole trap, and the electron in the low energy state can only jump through the jumping motion when the electron absorbing ambient provides enough energy to reach the excited state. Because the electron mobility is far greater than the hole, compared with the water-resident polylactic acid melt-blown nonwoven fabric, the charge energy carried by the water-resident polypropylene is higher, and the charge energy can be dissipated by absorbing the energy which is lower than the energy required by the charge transition of the polylactic acid, so that the charge storage performance is not as stable as the polylactic acid.
Silicon nitride has high dielectric constant and large forbidden bandwidth, and is a nonpolar electret material with good hydrophobicity. When the polylactic acid melt-blown cloth after water is in a pole state is dried by heat, the outside provides heat energy to enable the silicon nitride partial valence electrons to absorb enough energy to jump to the guide belt, and partial valence electrons break loose and bind along with evaporation of water molecules to be free electrons to escape into the air, and meanwhile holes are reserved. Because polylactic acid and water contact friction also generate a large number of holes, the polylactic acid and the water contact friction can jointly contribute to the improvement of the filtration performance of the melt-blown nonwoven material. And a large amount of electrons are generated after the polypropylene water is in a pole, valence electrons in the silicon nitride are absorbed by energy during drying and break loose to become free electrons to escape into the air, holes are reserved, electrons which jump in melt-blown fibers and electrons which are adjacent to the holes are captured by the holes to form neutrality, and therefore the charge amount of the water-in-pole melt-blown polypropylene non-woven fabric is reduced, and the phenomenon that the filtering effect of the water-in-pole melt-blown non-woven fabric is reduced is caused. Therefore, even if the polypropylene melt-blown nonwoven fabric added with nano silicon nitride is subjected to water electret treatment, the filtering performance of the obtained melt-blown nonwoven fabric is far inferior to that of the polylactic acid water electret melt-blown nonwoven fabric prepared by the application.
Compared with the prior art, the degradable water-resident melt-blown air filter with the sandwich structure has the advantages that: the air filter prepared by the application adopts the bio-based polylactic acid as the raw material, and three layers of the air filter can be biodegraded into carbon dioxide and water, so that no microplastic is produced, and the air filter is environment-friendly; the air filter prepared by the application has higher filtering performance than the existing polylactic acid melt-blown cloth, and the advantage benefits from the addition of electret nano silicon nitride and water electret treatment technology.
The beneficial effects are that:
(1) According to the preparation method of the polylactic acid electret melt-blown non-woven fabric, the nano silicon nitride is added to improve the filtering performance of the polylactic acid melt-blown non-woven fabric, and the prepared polylactic acid aqueous solution of the polylactic acid electret melt-blown non-woven fabric containing the nano silicon nitride is added to obviously improve the filtering performance of the polylactic acid melt-blown non-woven fabric and has long service life although the fiber diameter is increased due to the addition of the nano silicon nitride.
(2) The polylactic acid electret melt-blown non-woven fabric prepared by the application is used for preparing a degradable water electret melt-blown air filter, and three layers of polylactic acid are biodegradable into carbon dioxide and water, so that no microplastic is generated, and the degradable water electret melt-blown air filter is environment-friendly.
Detailed Description
The application is further described below in conjunction with the detailed description. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. Furthermore, it should be understood that various changes and modifications can be made by one skilled in the art after reading the teachings of the present application, and such equivalents are intended to fall within the scope of the application as defined in the appended claims.
The testing method comprises the following steps:
filtration efficiency: the test is carried out by adopting a TSI8130 automatic filter material tester, and the flow rate of sodium chloride particles with the average diameter of 0.3 mu m is set to be 32L/min or 85L/min.
Example 1
A preparation method of polylactic acid electret melt-blown non-woven fabric comprises the following specific steps:
(1) Uniformly mixing nano silicon nitride (microphone, S817701) and dried levorotatory polylactic acid (Anhuifengyuan, FY 201) with water content less than 0.005%, and then carrying out melt extrusion, water cooling and granulating to obtain melt-blown electret master batch;
the technological parameters of the twin-screw extruder are as follows: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die head temperature 190 ℃, the main machine rotating speed 12rpm, the feeding speed 10rpm, the water cooling is circulating tap water, and the granulating speed is 12rpm;
(2) Preparing polylactic acid melt-blown non-woven fabric containing nano silicon nitride by using the dried polylactic acid with the water content less than 0.005% and the melt-blown electret master batch in the step (1) through a melt-blowing process;
the melt blowing process parameters were as follows:
the temperatures of the first region and the fifth region of the screw extruder are 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and 230 ℃ respectively, and the die head temperature is 230 ℃;
the frequency of the metering pump is 20Hz;
the temperature of hot air is 245 ℃, and the pressure of hot air is 0.15MPa;
the receiving distance is 18cm, and the frequency of the net conveying curtain is 8Hz;
(3) Water electret treatment: pure water with the resistivity of 18.2MΩ & cm after purification is sprayed out from a fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 2.8MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 1.5Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of PTFE material compression rollers in a hot air drying system with the temperature of 45 ℃ and two pairs of PTFE material compression rollers in an outlet are used for rubbing the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid electret melt-blown non-woven fabric is obtained after drying; wherein, the extrusion force of 3N is formed between the upper 4 rollers and the lower 4 rollers in the 4 pairs of compression rollers.
The content of nano silicon nitride in the prepared polylactic acid electret melt-blown non-woven fabric is 0.5 weight percent; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.89 percent at the flow rate of 32L/min, which is 13.51 percent higher than that of a comparison sample; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 98.82 percent at the flow rate of 85L/min, which is 20.18 percent higher than that of a comparative sample, and the comparative sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown nonwoven fabric without nano silicon nitride.
Comparative example 1
A method for preparing polylactic acid electret melt-blown nonwoven fabric is basically the same as in example 1, except that calcium stearate with equal mass and equal particle diameter is used for replacing nano silicon nitride in step (1).
The filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.0% at the flow rate of 32L/min; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with an average diameter of 0.3 μm was 96.78% at a flow rate of 85L/min.
Comparing comparative example 1 with example 1, it can be found that the filtration efficiency of comparative example 1 is reduced at both 32L/min flow rate and 85L/min flow rate, because the nano silicon nitride has a large forbidden band width, high interface trap density, good space charge storage capability, high dielectric constant, and positive hole charge generated by the transition of valence electrons excited by heating during drying, has electrical consistency with the formation of a large number of holes of polylactic acid treated by water residence, and has good electronegativity of nitrogen element, while the dielectric property of calcium stearate is lower than that of silicon nitride, and has hygroscopicity, which is unfavorable for drying after water residence, if the drying takes longer thoroughly, this will result in dissipation of more charges under the action of heat, and in the long-term storage process of the meltblown, calcium stearate absorbs a large amount of moisture in the air, accelerates the dissipation of the charge of the meltblown, resulting in attenuation of the filtration performance of the meltblown, so the filtration performance of polylactic acid after adding silicon nitride is obviously superior to that of calcium stearate.
Example 2
A preparation method of polylactic acid electret melt-blown non-woven fabric comprises the following specific steps:
(1) Uniformly mixing nano silicon nitride (microphone, S817701) and dried levorotatory polylactic acid (Anhuifengyuan, FY 201) with water content less than 0.005%, and then carrying out melt extrusion, water cooling and granulating to obtain melt-blown electret master batch;
the technological parameters of the twin-screw extruder are as follows: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die head temperature 190 ℃, the main machine rotating speed 12rpm, the feeding speed 10rpm, the water cooling is circulating tap water, and the granulating speed is 12rpm;
(2) Preparing polylactic acid melt-blown non-woven fabric containing nano silicon nitride by using the dried polylactic acid with the water content less than 0.005% and the melt-blown electret master batch in the step (1) through a melt-blowing process;
the melt blowing process parameters were as follows:
the temperatures of the first region to the fifth region of the screw extruder are 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and 240 ℃ of the die head temperature respectively;
the frequency of the metering pump is 17Hz;
the temperature of hot air is 250 ℃, and the pressure of hot air is 0.2MPa;
the receiving distance is 20cm, and the frequency of the net conveying curtain is 6.3Hz;
(3) Water electret treatment: pure water with the resistivity of 18.2MΩ & cm after purification is sprayed out from a fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 2MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 1Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of FEP material compression rollers in a hot air drying system with the temperature of 50 ℃ and two pairs of FEP material compression rollers in an outlet are used for rubbing the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid electret melt-blown non-woven fabric is obtained after drying; wherein, 4 extrusion force of 5N is formed between 4 rollers above and 4 rollers below in 4 pairs of compression rollers.
The content of nano silicon nitride in the prepared polylactic acid electret melt-blown non-woven fabric is 0.2wt%; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.92 percent at the flow rate of 32L/min, which is 13.82 percent higher than that of a comparison sample; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 98.78 percent at the flow rate of 85L/min, which is 20.35 percent higher than that of a comparison sample, and the comparison sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown nonwoven fabric without nano silicon nitride.
Example 3
A preparation method of polylactic acid electret melt-blown non-woven fabric comprises the following specific steps:
(1) Uniformly mixing nano silicon nitride (microphone, S817701) and dried levorotatory polylactic acid (Anhuifengyuan, FY 201) with water content less than 0.005%, and then carrying out melt extrusion, water cooling and granulating to obtain melt-blown electret master batch;
the technological parameters of the twin-screw extruder are as follows: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die head temperature 190 ℃, the main machine rotating speed 12rpm, the feeding speed 10rpm, the water cooling is circulating tap water, and the granulating speed is 12rpm;
(2) Preparing polylactic acid melt-blown non-woven fabric containing nano silicon nitride by using the dried polylactic acid with the water content less than 0.005% and the melt-blown electret master batch in the step (1) through a melt-blowing process;
the melt blowing process parameters were as follows:
the temperatures of the first region and the fifth region of the screw extruder are 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and 230 ℃ respectively, and the die head temperature is 230 ℃;
the frequency of the metering pump is 18Hz;
the temperature of hot air is 245 ℃, and the pressure of hot air is 0.24MPa;
the receiving distance is 23cm, and the frequency of the net conveying curtain is 6Hz;
(3) Water electret treatment: pure water with the resistivity of 18.2MΩ & cm after purification is sprayed out from a fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 2.5MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 2Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of PTFE material compression rollers in a hot air drying system with the temperature of 50 ℃ and two pairs of PTFE material compression rollers in an outlet are used for rubbing the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid electret melt-blown non-woven fabric is obtained after drying; wherein, 4 extrusion force of 5N is formed between 4 rollers above and 4 rollers below in 4 pairs of compression rollers.
The content of nano silicon nitride in the prepared polylactic acid electret melt-blown non-woven fabric is 0.25wt%; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.98 percent at the flow rate of 32L/min, which is 14.08 percent higher than that of a comparison sample; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.05 percent at the flow rate of 85L/min, which is 20.74 percent higher than that of a comparison sample, and the comparison sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown nonwoven fabric without nano silicon nitride.
Example 4
A preparation method of polylactic acid electret melt-blown non-woven fabric comprises the following specific steps:
(1) Uniformly mixing nano silicon nitride (microphone, S817701) and dried levorotatory polylactic acid (Anhuifengyuan, FY 201) with water content less than 0.005%, and then carrying out melt extrusion, water cooling and granulating to obtain melt-blown electret master batch;
the technological parameters of the twin-screw extruder are as follows: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die head temperature 190 ℃, the main machine rotating speed 12rpm, the feeding speed 10rpm, the water cooling is circulating tap water, and the granulating speed is 12rpm;
(2) Preparing polylactic acid melt-blown non-woven fabric containing nano silicon nitride by using the dried polylactic acid with the water content less than 0.005% and the melt-blown electret master batch in the step (1) through a melt-blowing process;
the melt blowing process parameters were as follows:
the temperatures of the first region and the fifth region of the screw extruder are 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and 235 ℃ of the die head temperature respectively;
the frequency of the metering pump is 16Hz;
the temperature of hot air is 245 ℃, and the pressure of hot air is 0.18MPa;
the receiving distance is 24cm, and the frequency of the net conveying curtain is 7.2Hz;
(3) Water electret treatment: pure water with the resistivity of 18.2MΩ & cm after purification is sprayed out from a fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 3MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 1.5Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of FEP material compression rollers in a hot air drying system with the temperature of 52 ℃ and two pairs of FEP material compression rollers in an outlet are used for rubbing the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid electret melt-blown non-woven fabric is obtained after drying; wherein, the extrusion force of 6N is formed between the upper 4 rollers and the lower 4 rollers in the 4 pairs of compression rollers.
The content of nano silicon nitride in the prepared polylactic acid electret melt-blown non-woven fabric is 0.1 weight percent; the filtration efficiency of the polylactic acid electret melt-blown non-woven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.81 percent at the flow rate of 32L/min, which is 12.8 percent higher than that of a comparison sample; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 98.64 percent at the flow rate of 85L/min, which is 19.73 percent higher than that of a comparative sample, and the comparative sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown nonwoven fabric without nano silicon nitride.
Example 5
A preparation method of polylactic acid electret melt-blown non-woven fabric comprises the following specific steps:
(1) Uniformly mixing nano silicon nitride (microphone, S817701) and dried levorotatory polylactic acid (Anhuifengyuan, FY 201) with water content less than 0.005%, and then carrying out melt extrusion, water cooling and granulating to obtain melt-blown electret master batch;
the technological parameters of the twin-screw extruder are as follows: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die head temperature 190 ℃, the main machine rotating speed 12rpm, the feeding speed 10rpm, the water cooling is circulating tap water, and the granulating speed is 12rpm;
(2) Preparing polylactic acid melt-blown non-woven fabric containing nano silicon nitride by using the dried polylactic acid with the water content less than 0.005% and the melt-blown electret master batch in the step (1) through a melt-blowing process;
the melt blowing process parameters were as follows:
the temperatures of the first region to the fifth region of the screw extruder are 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and 240 ℃ of the die head temperature respectively;
the frequency of the metering pump is 19Hz;
the temperature of hot air is 255 ℃, and the pressure of hot air is 0.28MPa;
the receiving distance is 26cm, and the frequency of the net conveying curtain is 7.5Hz;
(3) Water electret treatment: pure water with the resistivity of 18.2MΩ & cm after purification is sprayed out from a fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 4MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 3Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of PTFE material compression rollers in a hot air drying system with the temperature of 55 ℃ and two pairs of PTFE material compression rollers in an outlet are used for rubbing the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid electret melt-blown non-woven fabric is obtained after drying; wherein, the extrusion force of 7N is formed between the upper 4 rollers and the lower 4 rollers in the 4 pairs of compression rollers.
The content of nano silicon nitride in the prepared polylactic acid electret melt-blown non-woven fabric is 1wt%; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.85 percent at the flow rate of 32L/min, which is 13.17 percent higher than that of a comparison sample; the filtration efficiency of the polylactic acid electret melt-blown nonwoven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 98.77 percent at the flow rate of 85L/min, which is 19.96 percent higher than that of a comparative sample, and the comparative sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown nonwoven fabric without nano silicon nitride.
Example 6
A preparation method of a degradable water-resident electrode melt-blown air filter comprises the following specific steps:
(1) Melting and extruding the dried high-melt-index dextrorotatory polylactic acid (Anhuifeng original, FY 602) by a screw extruder, wherein the temperature of a 1-5 region of the screw extruder is 195 ℃, 2105, 220 ℃, 225 ℃, 230 ℃, the temperature of a die head is 230 ℃, the temperature of a liquid box is 260 ℃, spun-bonded filaments are ejected from a spinneret orifice, and the spun-bonded filaments are subjected to high-speed negative pressure air draft of 0.5MPa and air flow filament separation to form polylactic acid spun-bonded non-woven fabrics on a net conveying curtain;
(2) The two layers of polylactic acid spunbonded nonwoven fabrics and the polylactic acid electret melt-blown nonwoven fabrics in any one of the embodiments 1 to 5 are subjected to ultrasonic thermal bonding to obtain degradable water electret air filtering nonwoven fabrics;
the prepared degradable water electret air filtering nonwoven fabric is of a sandwich structure, the middle layer of the degradable water electret air filtering nonwoven fabric is polylactic acid electret melt-blown nonwoven fabric, and the upper layer and the lower layer are polylactic acid spun-bonded nonwoven fabrics.
(3) And (3) cutting the degradable water electret air filtering nonwoven fabric in the step (2), and packaging by an automatic folding machine to obtain the degradable water electret melt-blown air filter.

Claims (9)

1. A preparation method of polylactic acid electret melt-blown non-woven fabric is characterized in that: carrying out water electret treatment on the polylactic acid melt-blown non-woven fabric containing nano silicon nitride to prepare the polylactic acid electret melt-blown non-woven fabric;
the content of nano silicon nitride in the polylactic acid melt-blown nonwoven fabric is 0.1-1 wt%;
the filtration efficiency of the polylactic acid electret melt-blown non-woven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 99.81% -99.98% at the flow rate of 32L/min, and is higher than that of a comparative sample by 12.8%, the filtration efficiency of the polylactic acid electret melt-blown non-woven fabric on sodium chloride particles with the average diameter of 0.3 mu m is 98.64-99.05% at the flow rate of 85L/min, and is higher than that of the comparative sample by 19.73%, and the comparative sample is prepared by carrying out water electret treatment on the polylactic acid melt-blown non-woven fabric without nano silicon nitride.
2. The method for preparing the polylactic acid electret melt-blown non-woven fabric according to claim 1, wherein the polylactic acid melt-blown non-woven fabric containing nano silicon nitride is prepared by a melt-blowing process of dried levorotatory polylactic acid and melt-blown electret master batch;
the melt-blown electret master batch is obtained by uniformly mixing nano silicon nitride and dried L-polylactic acid according to the mass ratio of 1:4-9, then melt-extruding, and then water-cooling and granulating;
the melt index of the L-polylactic acid is more than 30g/10min under the conditions of 230 ℃ and 2.16kg pressure.
3. The method for preparing the polylactic acid electret melt-blown non-woven fabric according to claim 2, wherein the water content of the dried levorotatory polylactic acid is less than 0.005%.
4. The method for preparing the polylactic acid electret melt-blown non-woven fabric according to claim 2, wherein the melt-blowing process parameters are as follows:
the temperature of the first to the fifth areas of the screw extruder is 180 ℃, 190 ℃, 200 ℃, 220 ℃, 230 ℃ and the die head temperature is 230-240 ℃ respectively;
the frequency of the metering pump is 16-20 Hz;
the temperature of hot air is 245-255 ℃, and the pressure of hot air is 0.15-0.28 MPa;
the receiving distance is 18-26 cm, and the frequency of the net conveying curtain is 6-8 Hz.
5. The method for preparing the polylactic acid electret melt-blown nonwoven fabric according to claim 2, wherein the technological parameters of the twin-screw extruder are as follows: the temperatures of the first region and the fourth region are 170 ℃, 175 ℃, 180 ℃, 190 ℃, the die temperature 190 ℃, the main machine rotating speed of 12rpm, the feeding speed of 10rpm, the water cooling is the circulating tap water, and the granulating speed of 12rpm.
6. The method for preparing the polylactic acid electret melt-blown non-woven fabric according to claim 1, wherein the water electret treatment process is as follows: the purified pure water is sprayed out from a fan-shaped nozzle under the action of a high-pressure water pump, the polylactic acid melt-blown non-woven fabric containing nano silicon nitride passes through fan-shaped high-pressure water mist with the pressure of 2-4 MPa on the upper side and the lower side to carry out electret under the drive of a net conveying curtain with the frequency of 1-3 Hz, meanwhile, a negative pressure suction system below the net conveying curtain pumps water in the melt-blown fabric, two pairs of PTFE or FEP material compression rollers in a hot air drying system with the temperature of 45-55 ℃ and two pairs of PTFE or FEP material compression rollers in an outlet are used for rubbing the polylactic acid melt-blown non-woven fabric containing nano silicon nitride, and the polylactic acid electret melt-blown non-woven fabric is obtained after drying.
7. The method for producing a polylactic acid electret melt-blown nonwoven fabric according to claim 6, wherein a pressing force of 3 to 7N is formed between the upper 4 rolls and the lower 4 rolls in the 4 pairs of pressing rolls.
8. A preparation method of a degradable water-resident melt-blown air filter is characterized by comprising the following steps of: cutting the degradable water electret air filtering nonwoven fabric, and packaging by an automatic folding machine to obtain a degradable water electret melt-blown air filter;
the degradable water electret air filtering nonwoven fabric is of a sandwich structure, and is obtained by carrying out ultrasonic thermal bonding on two layers of polylactic acid spunbonded nonwoven fabrics and polylactic acid electret melt-blown nonwoven fabrics prepared by adopting the method of any one of claims 1 to 7; the middle layer of the degradable water electret air filtering nonwoven fabric is polylactic acid electret melt-blown nonwoven fabric, and the upper and lower layers are polylactic acid spunbonded nonwoven fabric.
9. The method for preparing the degradable water-resident melt-blown air filter according to claim 8, wherein the polylactic acid spunbonded nonwoven fabric is prepared by the following steps: melting and extruding the dried high-melt-index dextrorotatory polylactic acid through a screw extruder, wherein the temperature of a 1-5 region of the screw extruder is 195 ℃, 210 ℃, 220 ℃, 225 ℃, 230 ℃, the temperature of a die head is 230 ℃, the temperature of a liquid box is 260 ℃, and spinning filaments are sprayed out from a spinneret orifice, and the polylactic acid spun-bonded non-woven fabric is formed on a net conveying curtain through high-speed negative pressure air draft of 0.5MPa and air flow filament separation; the melt index of the high-melting-point dextrorotatory polylactic acid is more than 20g/10min under the conditions of 230 ℃ and 2.16kg pressure.
CN202310949192.XA 2023-07-31 2023-07-31 Preparation method and application of polylactic acid electret melt-blown non-woven fabric Pending CN117144557A (en)

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