JP2006283240A - Web-producing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a web-producing apparatus enabling substantial increase of web production speed of an electrospinning web production process. <P>SOLUTION: The apparatus for producing a web by electrospinning process has a spinning head having a nozzle to eject a polymer substance, a collector to collect the polymer substance ejected from the nozzle and an electric source to supply a voltage between the nozzle and the collector. The apparatus has a plurality of nozzles on the spinning head and auxiliary electrodes formed between the multiple nozzles and the nozzle has an electric potential different from that of the auxiliary electrode. The potential applied to the auxiliary electrode of the web-production apparatus is 50.0-99.9% of the potential between the nozzle and the collector. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a manufacturing apparatus for forming a submicron to micron diameter fiber as a web from a polymer material such as a polymer solution or a polymer melt using an electrospinning method. The present invention relates to a method of manufacturing a web using an apparatus. More specifically, the present invention is a manufacturing apparatus that can dramatically improve the web manufacturing speed by the electrospinning web method.

  There are various methods for obtaining fibers and webs from synthetic resins. Fibers that can be produced by the melt spinning method, wet spinning method, and dry and wet spinning method have a diameter in the range of several to several tens of μm. It has been impossible to produce fibers of micron to several microns except for special means such as melting and removing a part of fibers of a specific polymer. (Non-Patent Document 1)

On the other hand, according to the electrospinning method, various kinds of polymer materials can be made into a web of fibers having a diameter of several nanometers to several micrometers, and therefore, the ratio of the surface area to the volume is larger than other methods. A web with high porosity can be produced.
The principle is as follows. That is, when a liquid polymer material having electrical conductivity is ejected from a nozzle having a voltage between the electrode plates arranged opposite to each other, a droplet of the polymer material is charged and simultaneously stretched in the direction of the collector portion. It grows in a shape. When the surface tension of the droplet exceeds the repulsive force due to the charged charge, the state becomes unstable and spreads like a flash, that is, the jet breaks up. A web is formed by adhering in a mesh form on the electrode.
It is said that US Patent No. 1975504 (Patent Document 1) is the first patent for the electrospinning method. Although its history is old, there is a problem that the production speed is slow. (Non-Patent Documents 1 to 3).

  However, in recent years, the production of webs by the electrospinning method has been energetically studied in application fields such as medical and biotechnology such as artificial blood vessels and artificial organs due to its characteristics (Patent Documents 2 to 8). Also, in the United States in the early 1990s, it was taken up as military research for producing gas filters for biological weapons, and various other reports on electrospinning technology using a single nozzle were made. For example, Patent Document 9 discloses a method for producing EVOH or PVA nanofiber bodies by electrospinning from an (aqueous) solution of EVOH (ethylene vinyl alcohol copolymer) or PVA (polyvinyl alcohol). . As an example of practical use, it is put into practical use as a special air filter for gas turbines and automobiles by Donaldson Company (Non-Patent Document 4).

However, poor productivity due to slow manufacturing speed remained a problem. Attempts have been made to increase the production speed by providing a large number of nozzles in the spinning head. However, when a large number of nozzles are provided, problems due to electric field interference between the nozzles occurred.
As an example of using a large number of nozzles, Patent Document 14 discloses an industrial technique in which a large number of nozzles are arranged by providing a plate electrode, a scanning electrode, or an electrostatic quadrupole lens between a spinning head and a collector. A device that can be manufactured is proposed, and a slit-shaped spinneret is also proposed, but a sufficient processing speed cannot be obtained. Further, Patent Document 15 proposes a method of improving the processing speed by using a charge distribution plate in the middle of a large number of arranged nozzles. However, electric field interference between nozzles (needles in the patent text) is considered. However, since the electric field does not concentrate and is weak, there is a problem in quality such as a granular lump contained in the fiber, and there are many problems in processing conditions.

U.S. Pat. No. 1975504 U.S. Pat.No. 4,044,404 U.S. Pat. No. 4,323,525 U.S. Pat. No. 4,552,707 U.S. Pat. No. 4,842,505 U.S. Pat. No. 4,904,272 US Pat. No. 5,866,217 US Patent US2003 / 0215624 US Patent US2003 / 0190383 U.S. Patent No. 6713011 Japanese Patent No. 3525382 Journal of the Textile Society of Japan Vol.59, No.1 p3 (2003) Journal of Polymer Science, Vol.59, No.11, pp.706-709 (Nov., 2002) Journal of Polymer Science: Part b: Polymer Physics, Vol. 37, 3488-3493 (1999) International Nonwovens Technical Conference (Joint INDA TAPPI Conference), Atlanta, Georgia, September 24-26, 2002.

  An object of the present invention is to provide a web manufacturing apparatus that prevents interference of an electric field between nozzles of a web manufacturing apparatus by an electrospinning method having a plurality of nozzles, efficiently takes out fibers from a large number of nozzles, and improves the web manufacturing speed. The task is to do.

In order to solve the above problems, the present invention takes the following means.
A first aspect of the present invention is a spinning head unit having a nozzle for injecting a polymer material, a collector unit for collecting the polymer material injected from the nozzle, and a power source for supplying a voltage between the nozzle and the collector unit. A web manufacturing apparatus using an electrospinning method having a plurality of nozzles and an auxiliary electrode existing between the nozzles in a spinning head unit, wherein the nozzle and the auxiliary electrode can have different potentials. .

  A second aspect of the present invention is the web manufacturing apparatus according to the second aspect of the present invention, wherein the potential applied to the auxiliary electrode is 50.0 to 99.9% of the potential with respect to the collector portion of the nozzle.

  A third aspect of the present invention is the web manufacturing apparatus according to any one of the first and second aspects of the present invention, wherein the nozzle is surrounded by an auxiliary electrode.

  A fourth aspect of the present invention is the web manufacturing apparatus according to any one of the first to third aspects of the present invention, wherein the auxiliary electrode forms a lattice-like cell, and a nozzle is disposed in the cell.

  A fifth aspect of the present invention is the web manufacturing apparatus according to any one of the first to fourth aspects of the present invention, wherein the tip of the auxiliary electrode is the same as the tip of the nozzle or protrudes from the tip of the nozzle.

  A sixth aspect of the present invention is the web manufacturing apparatus according to any one of the first to fifth aspects of the present invention, wherein a distance between the nozzle and the auxiliary electrode is 10 to 50% of a distance between the nozzle tip and the collector portion.

  A seventh aspect of the present invention is the nozzle according to any one of the first to sixth aspects, wherein the outer diameter of the nozzle is 2 mm or less, the inner diameter is 1 mm or less, and the length is 10 times or more of the outer diameter. It is a web manufacturing device.

  According to the present invention, it has become possible to dramatically improve the web production speed by the electrospinning method.

  The inventor of the present invention provides a spinning head unit having a nozzle that ejects a polymer material, a collector unit that collects the polymer material ejected from the nozzle, and an electropower source that supplies a voltage between the nozzle and the collector unit. In a web manufacturing apparatus using a spinning method, a plurality of nozzles and auxiliary electrodes existing between the nozzles are provided in a spinning head unit, and the nozzles and the auxiliary electrodes are set to different potentials, so that electrical It has been found that interference can be prevented and the web production speed can be greatly improved. By preventing electrical interference between the nozzles by the auxiliary electrode, the manufacturing speed can be improved because the electric field strength at the tip of each nozzle is increased.

The auxiliary electrode is an electrode to which a voltage lower than that of the nozzle is applied. If the voltage of the auxiliary electrode is equal to or higher than the voltage of the nozzle, the electrical interference generated between the nozzles cannot be cut off, so that the processing speed cannot be improved.
Further, when the voltage of the auxiliary electrode is made lower than the nozzle voltage, the shielding effect by the auxiliary electrode is produced, and the electric field strength distribution is compressed at the tip of each nozzle, so that the effect of improving the processing speed can be obtained.
However, if the voltage of the auxiliary electrode is too low, the force that attracts the fibers ejected from the nozzle to the collector and the force that is attracted to the auxiliary electrode balances, causing a problem that the fibers adhere to the auxiliary electrode.

In the present invention, the voltage between the nozzle and the collector is preferably 1 to 500 kV, more preferably 2 kV to 200 kV, and still more preferably 5 kV to 100 kV. If the voltage exceeds 500 kV, a short circuit may occur between the electrodes (between the nozzle and the collector). In addition, device leakage and discharge are likely to occur, making insulation difficult. In addition, when the voltage is less than 1 kV, the electrospinning phenomenon hardly occurs.
In the electrospinning method, generally, the higher the applied voltage, the thinner the fiber obtained.

The ratio of the electric potential applied to the auxiliary electrode to the electric potential with respect to the collector portion of the nozzle affects the processing speed. The smaller the voltage of the auxiliary electrode, the stronger the concentration of the electric field, and as a result, the production speed increases. However, if the voltage is too low, the distance between the nozzle and the auxiliary electrode is smaller than the distance between the nozzle and the collector, so that a discharge occurs between the nozzle and the auxiliary electrode, or the fibers ejected from the nozzle are collected in the collector. There is a possibility that the problem that it becomes easy to adhere to the auxiliary electrode without going to the portion may occur.
As a result of verifying the optimum range of the voltage ratio between the nozzle and the auxiliary electrode for the above problem, the ratio of the voltage of the auxiliary electrode (voltage of the auxiliary power supply) to the voltage of the nozzle (voltage of the main power supply) is preferably in the present invention. 50 to 99.9%, more preferably 70 to 99.9%.

Furthermore, in the present invention, it is desirable that each nozzle be surrounded by an auxiliary electrode because it is possible to effectively prevent electrical interference between the nozzles.
The structure in which the nozzle is surrounded by the auxiliary electrode is a cell structure in which the auxiliary electrode attached to the spinning head, like the nozzle, can surround the nozzle at a certain height, and the nozzle is arranged in the cell. Means a structured.
For example, a spinning head can be manufactured by forming a cell by forming a hole in a metal plate such as a thick steel plate as an auxiliary electrode, and disposing each nozzle in the cell.

  However, in order to obtain an auxiliary electrode that is lighter, saves material, is simple to manufacture, and is low in cost, specifically, a cell in which plate-like auxiliary electrodes are combined in a lattice shape is formed, It is desirable to adopt a structure in which the nozzle is arranged in the cell.

The height of the auxiliary electrode is more preferably a structure in which the tip of the auxiliary electrode is the same as the nozzle tip or protrudes from the nozzle tip.
In the electrospinning method, a high-molecular substance (jet) sprayed from the tip of the nozzle is stretched in the direction of the collector and stretched in a streak, and after a certain distance, the state becomes unstable and spreads in a flash manner. That is, jet breakup occurs.
At this time, since the jet before breakup has electrical conductivity, it causes interference as well as electrical interference between nozzles.
For this reason, in order for the auxiliary electrode to exhibit higher shielding properties, it is desirable that the tip of the auxiliary electrode is the same as the nozzle tip or protrudes from the nozzle tip.
However, if the tip of the auxiliary electrode protrudes to the collector side from the position where the jet breaks up, the fibers are likely to adhere to the auxiliary electrode. In addition, as the liquid polymer material ejected from the nozzle moves away from the nozzle, the resistance increases due to a decrease in mobility due to evaporation of the solvent (in the case of a solution) or solidification due to a decrease in temperature (in the case of a melt). Since the voltage drops abruptly, it is not necessary to protrude the tip of the auxiliary electrode more than necessary in the direction of the collector part from the break-up position.

Considering the spread of fibers due to breakup, the position of the tip of the auxiliary electrode is preferably 0 to 30 mm, more preferably 0 to 20 mm when the position aligned with the nozzle tip is 0 mm, and preferably protrudes to the collector side.
If the electric field is increased by increasing the voltage between the nozzle and the collector, the distance between the nozzle tip and the point where the jet breaks up becomes shorter, and it is possible to generate a breakup at the nozzle tip. Therefore, the distance by which the auxiliary electrode is projected decreases as the voltage between the nozzle and the collector is increased.

In the electrospinning web method, by changing the distance between the nozzle tip and the collector portion, the fiber diameter and fiber length of the obtained fiber and the form of the mesh structure in which the fibers on the web are entangled change. For example, the longer the distance, the smaller the fiber diameter, and the shorter, the larger the fiber diameter.
Further, the distance can be increased, the jet spread can be increased, the coating range can be increased, and the dryness of the fibers can be improved. On the other hand, when the distance is shortened, the coating area is reduced, but the fibers are laminated in a weakly dried state, so that the adhesion can be improved.
The distance between the nozzle tip and the collector can be adjusted according to the purpose, but is preferably in the range of 1 cm to 1 m.

In the present invention, if the distance between the nozzle and the auxiliary electrode is increased with respect to the distance between the nozzle tip and the collector portion, the compression of the electric field strength distribution at the nozzle tip becomes weak, and the processing speed is reduced.
On the other hand, when the distance is reduced, the compression of the electric field strength distribution is strengthened. However, if the distance is too small, the force that the fibrous polymer substance is attracted to the collector portion is balanced with the force that is attracted to the collector part. There may be a problem that the fibers adhere to the auxiliary electrode, or air discharge may occur.
As a result of verifying the optimum range of the distance between the nozzle and the auxiliary electrode with respect to the distance between the nozzle and the collector, it is preferably 10 to 50%, more preferably 10 to 30% in the present invention.
By setting it as these ranges, said problem can be solved and realization of a higher processing speed is attained.

In the present invention, the shape of the nozzle preferably has an outer diameter of 2 mm or less and an inner diameter of 1 mm or less, and has a length of 10 times or more of the outer shape. By adopting such a shape, it is easy to form a jet and it is possible to improve the production speed.
Further, the inner diameter of the nozzle is suitable for a high-viscosity polymer substance having a thin inner diameter and low viscosity, and can be adjusted according to the viscosity of the polymer substance used, but preferably 10 μm to 10 mm, more preferably Is 100 μm to 1 mm.

In order to increase the electric field at the tip of the nozzle, the nozzle is preferably metallic. However, when the long and narrow metal tube as described above is used as a nozzle, there is a drawback that it is easily deformed. Further, there is a possibility that a short circuit may occur due to air discharge from the nozzle tip, and safety needs to be taken into consideration.
Further, the nozzle material is not limited to metal, and an insulator can be used if the electric conductivity of the solution used is high. However, a solution with high electrical conductivity has a tendency to be difficult to electrospin because the concentration of the electric field is relaxed electrically, and it has moderate conductivity in the sense of expanding the workable range of electrical conductivity of the solution. Is preferred. As a result of verifying the optimum range under many conditions, it was found that if the nozzle is a conductive material having a resistance value of 0 to 10 MΩ in the length direction, a sufficient electric field concentration occurs at the nozzle tip.
In addition, as a material having moderate conductivity, a material obtained by adding a conductive substance to an insulator such as glass or plastic to impart moderate conductivity is desirable.

In the electrospinning method, since the charged jet breaks up to form fine fibers, the fibers reaching the collector portion are also charged. Since the fibers are charged, the fibers coming out of adjacent nozzles repel each other. Therefore, in the vicinity of the intermediate point between the nozzles, the amount of fine fibers attached may decrease or may not adhere at all, which is a problem in obtaining a uniform web.
In order to solve the above problem, a plurality of nozzle rows (nozzle matrix) in which a plurality of nozzles of the spinning head portion are arranged at regular intervals on a straight line are arranged, and an intermediate point between the nozzles in the first row is arranged. In order to obtain a more uniform web, it is desirable to arrange the nozzle centers of the second row adjacent to the positions so as to form a matrix having a half-pitch shift by repeating this process.

  In the present invention, the auxiliary electrode is preferably made of a low-efficiency conductive material having a resistance of 1 MΩcm or less to the farthest position from the connection terminal.

In the present invention, it is desirable to use a collector part (roll or belt conveyor) having a resistivity of 1 MΩcm or less from the connection terminal to the farthest position.
If it is this range, the fiber collection efficiency at the time of web manufacture will be favorable, and the abnormal discharge and the safety at the time of failure can be aimed at. In addition to the metal, any material such as plastic may be used as long as the resistivity is the above.

Hereinafter, the polymer substance used in the present invention will be described.
When a jet of a polymer substance ejected, in which fibers are formed in the electrospinning method, breaks up, if the conductivity of the jet is less than 5 μScm, the potential at the tip of the jet may drop and the concentration of electric field strength may be weakened There is.
On the other hand, if the electrical conductivity exceeds 500 mS / cm, the electrospinning phenomenon tends to become unstable. If the electrical conductivity is high, the concentration of charges generated on the jet surface is not hydrodynamically buffered, but the charges are dispersed by electrical conduction, making it difficult for the jet breakup phenomenon to occur. .
As the polymer material used for producing the web in the present invention, it is desirable to use a material having a conductivity of 5 μScm to 500 mScm, preferably 5 μScm to 50 mScm. By using a material in such a range, it is possible to increase the electric field concentration at the tip of the jet after being ejected from the nozzle, to obtain a finer and better shaped fiber, and to improve the production speed.
In addition, the polymer substance to be used is not particularly limited in molecular weight from thousands of oligomers to millions of oligomers, and any material can be used as long as it can be liquefied and ejected from a nozzle. A polymer substance that can be made into a solution or dispersion by adding water and / or an organic solvent, a polymer substance that shows a liquid state when melted at room temperature or by heating, and the like can be arbitrarily used.
In the present invention, these polymer substances are mainly used in the form of an aqueous solution or an aqueous dispersion, but an organic solvent solution dissolved in an organic solvent such as alcohol, toluene, methyl ethyl ketone (MEK), xylene, or ethyl acetate. It can also be used as an organic solvent dispersion.

Hereinafter, polymer substances that can be used in the present invention are specifically shown.
Polymeric substances which can be used in the present invention and become liquid by heating and melting are polyolefin resins such as polyethylene and polypropylene, polystyrene, polyester, polyamide, polyethylene terephthalate, nylon, polycarbonate, polyvinylidene fluoride, polyurethane, polyacrylonitrile, poly Tetrafluoroethylene and the like.

The water-soluble polymer substance that can be used in the present invention is a natural polymer or a synthetic polymer having various hydrophilic groups, and in particular, a hydrogen bonding functional group such as a hydroxyl group, a carboxylic acid, and an amino group. , A polymer having a sulfonic acid, an amide group or the like is preferable.
Specifically, starches such as oxidized starch and dextrin; polyvinyl alcohol and its derivatives; carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose, carboxymethylcellulose, and pulp fiber Natural or synthetic cellulose such as cellulose itself; gelatin, casein, starch, collagen, gelatin; polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, polyhydroxyethyl acrylate, polyacryloylmorpholine, water-soluble polyvinyl acetal, poly-N-vinyl Acetamide, poly-N-vinylformamide, polyethylene glycol, poly Lactic acid poly (L-lactic acid), poly (lactide-CD-glycoside) polycaprolactan, polyphosphate ester poly (glycolic acid), poly (DL-lactic acid) and copolymers thereof, polyimide, polymethyl methacrylate, Polyvinyl ester, polyether, polycarbonate, polyacrylonitrile, polyvinyl pyrrolidone, proteoglycan, dextran, chitin, chitosan silk, hyaluronic acid, albumin, elastin, nucleic acid, heparin and heparan sulfate, or derivatives thereof, polylactic acid, polyglycolic acid, polylactide , Polyglutamic acid, poly-ε-caprolactone, poly-p-dioxane, polyα-malic acid and poly-β-hydroxybutyric acid, and a copolymer of polylactic acid and polycaprolactone, polyglutamic acid, polyglycolic acid Polylactic acid, polycaprolactone, copolymer of polylactic acid and polycaprolactone, poly-ε-caprolactone, poly-p-dioxane, poly α-malic acid, poly-β-hydroxybutyric acid, polyamide, polyester, polyurethane, polyvinyl Examples include alcohol, poly N isopropyl acrylamide, polyvinyl chloride, polymethyl methacrylate, polydimethylsiloxane, polyallylsulfone, and polysulfone.

Among these, polyvinyl alcohol and its derivatives, and starches are preferable because they are inexpensive and can obtain fine fibers having properties according to various purposes.
In addition, conductive polymers such as polyaniline, polyacetylene, polyazulene, polyphenylacetylene, polydiacetylene, polypyrrole, polythiophene, polybenzthiophene, polyparaphenylene, polyparaphenylene vinylene, polyimidazole, and polybenzimidazole can also be suitably used. .
Moreover, it is possible to use a polymer in which a substituent such as a hydroxyl group, an amino group, a carboxylic acid, or a sulfonic acid is introduced into these conductive polymers.

  These polymer substances may be used alone or in combination of two or more depending on the purpose. By mixing and using two or more kinds of polymer materials, the compatibility and the difference in solubility in the solvent (water or organic solvent) used at the time of production are adjusted, and the hydrophilicity and hydrophobicity of the resulting fiber. , Morphology (fiber diameter, fiber length, cross-sectional shape, fiber surface shape, etc.) can be adjusted.

  The water-dispersible polymer substance that can be used in the present invention is a so-called water-dispersed emulsion resin, specifically, acrylic acid ester, methacrylic acid ester, styrene, ethylene, butadiene, carboxylic acid or maleic acid. For example, conjugated diene polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic polymer, and the like. A copolymer copolymer latex such as a styrene-vinyl acetate copolymer, a polyurethane latex, and a polyester latex.

  In the present invention, in addition to the water-soluble polymer and the water-dispersible polymer, a hydrophobic resin that can be dissolved in an organic solvent such as alcohol or toluene can be used. Specifically, resins made of polymethacrylic acid esters such as ethyl cellulose, polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polyisopropyl methacrylate, or polymethacrylic acid derivatives, polystyrene resins (PS), acrylonitrile / Styrene copolymer resin (AS), acrylonitrile / butadiene / styrene copolymer resin (ABS), polyurethane resin, polyvinyl acetate resin and the like can be used.

In the present invention, a polymer substance that shows a liquid state at room temperature, for example, a silicon resin, or a radiation curable unsaturated organic compound such as a radiation curable oligomer or prepolymer can be used as a part of the organic solvent. .
These radiation curable unsaturated organic compounds are effective in improving the strength of fibers and the adhesion between fibers or between a fiber layer and a substrate by performing radiation irradiation as a post-treatment after forming the fiber layer.
In addition, the silicone resin is effective in terms of preventing water penetration by reducing friction and reducing surface energy.
The radiation curable unsaturated organic compound may be a monofunctional monomer, polyfunctional monomer or oligomer as long as it can form a highly crosslinked resin layer. These may be used alone or in combination of two or more. It may be a mixture. For example, oligomers include (1) epoxy acrylates such as bisphenol A type, bisphenol S type, bisphenol F type, epoxidized oil type, phenol novolac type, alicyclic type, (2) urethane acrylate (3) unsaturated polyester ( 4) Polyester acrylate (5) Polyether acrylate (6) Vinyl / acrylic oligomer (7) Polyene / thiol (8) Silicon acrylate (9) Polybutadiene acrylate (10) Polystyryl ethyl methacrylate
In addition, polydimethylsiloxane is used as the silicon resin.

The liquid polymer substance usable in the present invention can be used without limitation as long as it is liquid and can be ejected from a nozzle. Accordingly, various types of polymer materials such as an aqueous solution, an aqueous dispersion, an organic solution, and an organic dispersion may be used singly, but they can also be mixed and used at an arbitrary ratio.
In addition, various substances can be added to the liquid polymer substance as necessary within a range not impairing the effects of the present invention.
For example, in order to change the viscosity, surface tension, and conductivity of the solution or emulsion when the polymer material is used as a solution or emulsion, inorganic salts such as NaCl and polyphosphate, sodium salts of various carboxylic acids, Organic salts such as ammonium salts, anionic surfactants, cationic surfactants, amphoteric surfactants, surfactants such as nonionic surfactants, wetting agents such as polycarboxylic acids, sulfosuccinic acid and polyethylene glycol, Foaming agents, and salts such as styrene sulfonate, additives such as quaternary cations and amine compounds, coupling agents, crosslinking agents, water repellents such as water repellents, fibers to adjust conductivity It is possible to add a lubricant that reduces the friction. The polymer substance can include various pigments, dyes, inorganic sols, and inorganic gels.

The viscosity of the polymer substance used in the present invention affects the fiber diameter of the resulting fiber. Generally, when the viscosity is low, the fiber diameter is thin, and when the viscosity is high, the fiber diameter is thick.
The viscosity of the polymer substance is preferably 1 cps to 10000 cps in the tank, and more preferably 10 cps to 1000 cps. When the viscosity is high, the discharge amount from the nozzle decreases, and it becomes difficult to obtain fine fibers. On the contrary, if the viscosity is too low, it becomes difficult to control the discharge amount by the nozzle.

Since the electrospinning phenomenon occurs because the repulsive force of charges overcomes the surface tension, the surface tension of the polymer substance affects the fiber diameter of the resulting fiber. Generally, when the surface tension is low, the fiber diameter is thin, and when the surface tension is high, the fiber diameter is thick.
Further, if the surface tension of the polymer substance is too large, the electrospin phenomenon is difficult to occur, and not only the fiber becomes thick but also the liquid ball scatters. Similarly, it is preferably 60 dynes or less, and most preferably 50 dynes or less.
In addition, if the conductivity of the liquid polymer substance is large, the charge is not concentrated on the surface of the raw material solution coming out of the nozzle, and the electric charge is dispersed inside the raw material solution. Since it is thought that it does not express, it is preferably 1 μS / m to 500 mS / m. For the same reason, it is more preferably 5 μS / cm to 50 mS / cm. Generally, when the electrical conductivity is 500 mS / cm or more, the electrospinning phenomenon tends to become unstable.

In the production of a web by the electrospinning method, the fibers are usually collected on a continuous substrate web in a sheet form, instead of directly spraying the fibers on the collector portion.
At that time, it is desirable to use a base web having a surface resistance of 10 ¹² Ω / □ or less as the web to be used.
In the production of a web by the electrospinning method, charged fibers are continuously collected to form a fiber layer, so that electric charges are continuously conveyed to the base web. Therefore, if the surface resistance of the base web is high, the charged fiber charges may locally discharge on the base web or at the edges of the base web. However, when the surface resistance is 10 ¹² Ω / □ or less, the above-described local discharge can be prevented, and charges can be safely removed from the collector portion and the substrate web ground portion. Needless to say, a general static elimination equipment for bringing a conductive cloth, string, or brush into contact with the web or blowing ionized air onto the web may be provided.

  As the base web used in the present invention, paper, synthetic paper, film, nonwoven fabric and the like can be arbitrarily used.

The paper used as the base web in the present invention may be any paper as long as it is a paper made from various pulps. As for the types of pulp, chemical pulp fibers obtained by digesting coniferous and hardwood craft methods, sulfite methods, soda methods, polysulfide methods, etc., mechanical pulp fibers that have been pulped by mechanical force such as refiners and grinders, and after chemical pretreatment Examples thereof include semi-chemical pulp fibers pulped by mechanical force, waste paper pulp fibers, ECF pulp fibers, TCF pulp fibers and the like, which can be used in an unbleached or bleached state, respectively. Non-wood fibers produced from herbs include, for example, fibers obtained by pulping cotton, manila hemp, flax, straw, bamboo, pagas, kenaf and the like in the same manner as wood pulp.
In addition to the above pulp, chemicals such as a sizing agent, a paper strength agent, a yield improver, and fillers such as calcium carbonate, talc, clay, and silica can be internally and / or externally added.

Further, paper is mainly composed of cellulose fibers derived from various pulps, but in addition to cellulose fibers, glass fibers, carbon fibers, alumina fibers, silicon carbide fibers, etc., as long as the properties are not impaired. Inorganic fibers, aramid fibers, polyarylate fibers, polyolefin fibers, polyester fibers, polyamide fibers, polyacrylonitrile fibers, polyvinylidene fibers, and other organic fibers may be used. When the content is 50% by mass or more based on the total solid content constituting the paper support, it is preferable because sufficient electric resistance can be obtained.
In addition, paper that is generally available on the market can be used, and paper that is laminated with a thermoplastic resin such as polyethylene resin on the paper surface can also be used.

The material of the film used as the base web is not particularly limited, but polyolefins such as polypropylene, polyethylene, polybutene, and cyclic polyolefin, polyesters such as polyethylene terephthalate and polyethylene naphthalate, nylon 6, nylon 66, metaxylene Polyamides such as nylon are preferably used. In addition, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-butadiene, acrylic styrene, polymethyl methacrylate, polycarbonate, polyethersulfane, polyimide, polyacetal, liquid crystal polymer, polyvinyl alcohol, polyethylene vinyl alcohol, etc. It can be used. What modified | denatured the said synthetic resin with another monomer, an additive, etc. can be used, and what mixed several synthetic resin can also be used as needed.
Among these, polypropylene, polyethylene, cyclic olefin, polyethylene terephthalate, nylon, and polystyrene can be particularly preferably used.

The surface of the paper, synthetic paper, film, and nonwoven fabric used as the base web in the present invention is desirably subjected to an adhesion improving treatment for improving the adhesion of fine fibers formed on the base.
Specifically, the adhesion improving treatment is a method using irradiation with active energy rays such as corona discharge treatment, plasma discharge treatment, ultraviolet (UV) irradiation treatment, radiation (EB) irradiation treatment, flame treatment, and alkali metal solution treatment. And vapor deposition methods such as high-frequency sputter etching, PVD, and CVD.
In addition, as another method, a method of applying a composition mainly containing a resin or the like that improves adhesion to the surface of the base web can be used. As the composition constituting the coating layer, acrylate polymer, epoxy compound, urethane compound, polyethyleneimine, oxazoline group-containing polymer, polyamide polyurea resin, and the like used for pressure-sensitive adhesives and adhesives are preferably used. Is done.

The surface of the paper, synthetic paper, film, or nonwoven fabric used as the base web in the present invention is preferably subjected to an antistatic treatment for preventing charging due to the charge of the fine fibers.
Specifically, the antistatic treatment can employ various methods (external method, internal method) for preventing charging by reducing the surface resistivity of the base web, An internal method using an agent is preferred. Examples of the antistatic agent to be used include surfactants (for example, anionic compounds such as alkyl sulfates, cationic compounds such as alkyl ammonium salts, nonionic compounds such as polyoxyethyl and alkyl ethers), inorganic salts (hydrochloric acid, sulfuric acid, etc.) , Phosphoric acid, carbonic acid, sulfurous acid, phosphorous acid, salts of other inorganic acids with alkali metals, alkaline earth metals, ammonium ions, such as sodium chloride, magnesium chloride, etc., polyhydric alcohols (for example, ethylene glycol, propylene) Glycol, glycerin and the like and condensates thereof), metal compounds (for example, conductive fine particles such as titanium, tin, zinc and other metal oxides), carbon and the like.

  In addition, about the various adhesive improvement processing with respect to the above-mentioned base material web, and the antistatic processing, although the base material web to which these processing was given beforehand may be used, the fiber layer by the electrospinning of this invention is provided. It is more desirable to carry out continuously as a pre-process or post-process.

Hereinafter, a web manufacturing apparatus and a web manufacturing method according to the present invention will be specifically described with reference to the drawings.
FIG. 1 is one of the embodiments of the electrospinning web manufacturing apparatus of the present invention.
A tank 1 for storing a polymer substance, a pump 2 for pressurizing the polymer substance in the tank 1, a nozzle 3 for injecting a polymer substance supplied by the pump from the tip into a fine fiber, and a plurality of the nozzles 3 The attached spinning head unit 4, the supply control system 5 for controlling the supply of the polymer material, the insulating unit 6 associated with the spinning head unit 4, the auxiliary electrode 7 existing between the nozzles 3, and the jets from the nozzles 3 The collector unit 8 collects the produced fibers, the main power source 9 that applies a high voltage to the spinning head unit 4, and the auxiliary power source 10 that controls the potential of the auxiliary electrode 7.

As shown in FIG. 2, the manufacturing apparatus of the present invention includes an apparatus in which the spinning head unit 4 is grounded and a voltage is applied to the collector unit 8. Moreover, what applied the electrical polarity contrary to embodiment of FIG. 1, FIG. 2 is also contained.
However, since an electric discharge is likely to occur when a high voltage is applied, an embodiment in which the potential of the spinning head is higher than that of the collector is more desirable in the present invention.

  In the drawings of the present invention, one tank and one pump are shown, but a plurality of tanks and pumps can be used. For example, it is possible to store different polymer substances in a plurality of tanks and mix them in a flow path, or to supply a different polymer substance for each nozzle to produce a web.

In addition, the fiber diameter formed by this invention changes with the injection amount of a polymeric material. In addition, since the amount of polymer substance injected from the nozzle is very small, the state of the injected jet becomes unstable due to the pulsation of the pump and fluctuations in the output, resulting in variations in the fiber diameter, and granularity in the fiber May cause problems in quality, such as the inclusion of lumps. Further, excessive supply of the polymer substance causes dripping from the nozzle.
Therefore, in the present invention, a supply control system 5 is provided which can control and stabilize the pressure and flow rate of the polymer substance, can supply the spinning head unit with a constant pressure and a constant flow rate, and can adjust the injection amount from the nozzle. Desirable to get a good web.

Next, the structure of the auxiliary electrode 7 is shown in FIG.
The auxiliary electrode 7 is attached to the spinning head portion 4 having the nozzle 3 in an electrically insulated state, and forms a cell 11 surrounding the nozzle. The height of the auxiliary electrode is from the base portion of the nozzle to the position where the jet jetted from the nozzle breaks up.
FIG. 4 is a plan view showing the structure of the auxiliary electrode 7.
The auxiliary electrode 7 has a cell 11 surrounding each nozzle at a distance. The arrangement of the cells is arranged in accordance with the arrangement of the nozzles. The shape of the cell is ideal because the circle shown in FIG. 4 is ideal because the distance between the nozzle and the auxiliary electrode is constant, but practically any other shape such as a rhombus, square, hexagon or the like shown in FIG. 5 is adopted. It is possible. The rhombus and hexagon are effective in reducing the weight and rigidity of the auxiliary electrode.
Note that the distance between the nozzle 3 and the auxiliary electrode 7 is preferably 5 mm to 10 cm, and more preferably 1 to 5 cm.

In addition, a large number of nozzles can be arbitrarily arranged in the spinning head unit 4, but in order to form a uniform web, adjacent nozzle rows are shifted by a half pitch as shown in FIGS. An arrangement with a is desirable to obtain a more uniform web.
The nozzle is electrically connected to the main power source at the spinning head portion. However, if the liquid polymer is electrically conductive or has some electrical resistance at the connecting portion, the nozzle need not be completely connected. This brings great convenience by removing the nozzle for maintenance and inspection.
Desirably, the flow path in the spinning head is designed so that the supply amount and supply pressure of the polymer substance to each nozzle are equal. The pressure applied to each nozzle can be made uniform if the inner diameter of the flow path in the spinning head is much larger than the inner diameter of the nozzle. Furthermore, if the flow path inner diameter is increased, an effect of absorbing the pulsation of the pump output can be obtained, and a stable jet can be ejected.
Although not shown, it is also possible to provide a pressure stabilizing device and a pressure reservoir between the pump and the spinning head unit.

  Although the collector unit 8 is illustrated with a belt conveyor, any collector may be used as long as it can continuously collect fibers to form a web. Further, the distance from the collector portion 8 to the nozzle 3 can be appropriately selected according to the relationship between the potential of the nozzle and the auxiliary electrode and the situation such as the target fiber diameter.

  The voltage of the main power supply 9 applied between the nozzle 3 and the collector unit 8 is preferably selected in the range of preferably 1 kV to 500 kV, more preferably 2 kV to 200 kV, and even more preferably 5 kV to 100 kV.

  In the web production method by the electrospinning web production apparatus of the present invention, the liquid polymer material in the tank 1 is supplied to each nozzle 3 through the spinning head unit 4 by the pump 2. The main power source 9 jets a polymer material in a jet form from the nozzle tip while a high voltage is applied between the nozzle and the collector. The polymer material at the tip of the nozzle is charged and deforms thinly, but in the case of a solution, the solvent evaporates, and in the case of a heated melt, it becomes a fibrous solid by solidification due to a temperature drop and is collected by the collector part and the web. Become. At this time, a voltage is applied between the auxiliary electrode and the collector by the auxiliary power source 10. By adjusting the potential of the auxiliary electrode by adjusting the voltage of the auxiliary power supply, the shape of the jet jetted is optimally adjusted, and the fiber diameter and the like of the fine fibers are controlled.

  FIG. 6 shows an electrospinning web manufacturing apparatus according to the present invention including a web supply system and a web collection system. When a fine fiber layer is formed on a base web, the fine web layer is formed on the base web while moving the base web in close contact with the collector 8 and collected by the web collection system. To do. A known unwinder, winder, or the like can be arbitrarily employed for the web supply system and the web collection system.

  In addition, since a fine fiber is laminated | stacked on the base material web in the charged state, an electric charge is accumulate | stored on a base material web. Most of the electric charge becomes current to the collector, but when using a highly insulating base web or when laminated with highly insulating fine fibers, the electric charge accumulates locally and is not completely discharged. There is a case. It is more desirable to have a static elimination processing facility such as a grounding roll shown between the collector section and the web supply system, and between the collector section and the web collection system.

FIG. 7 shows an electrospinning web manufacturing apparatus according to the present invention, which has a pretreatment device and a posttreatment device.
The base web fed out from the web supply system is pretreated by a pretreatment device, a fine fiber layer is formed while being moved in close contact with the collector 8, the posttreatment is performed in the posttreatment device, and the web is recovered. Collect by system.

The pretreatment device mainly performs dust removal treatment, easy adhesion treatment, and the like on the base web. As a means for dust removal treatment, a known method such as a suction method or an electrostatic dust removal method can be arbitrarily adopted. Examples of the adhesion improving treatment include a method using irradiation of active energy rays such as a corona discharge treatment, a flame treatment, an alkali metal solution treatment, a high-frequency sputter etching treatment, and a vapor deposit method such as PVD and CVD. In addition, there is a method of coating a surface with a composition that improves adhesion.
In addition, as another method, a method of applying a composition mainly containing a resin or the like that improves adhesion to the surface of the base web can be used. As the composition constituting the coating layer, acrylate polymer, epoxy compound, urethane compound, polyethyleneimine, oxazoline group-containing polymer, polyamide polyurea resin, and the like used for pressure-sensitive adhesives and adhesives are preferably used. Is done.

The post-processing apparatus can mainly perform a static elimination process, a post-curing process, an easy adhesion process, a smoothing process, and the like on the base web on which the fine fibers are laminated.
There are various static elimination methods, such as a method of bringing a conductive cloth, string, etc., in contact with the surface of the web into contact with each other, a method of spraying water vapor, and attaching fine water droplets to the surface. Among these, the method of blowing ionized air onto the surface of the web is most preferable from the viewpoint of preventing contamination of the laminated surface and mixing of foreign substances. In particular, an apparatus that ionizes air by corona discharge and sprays it at a pressure of 0.05 MPa or more is effective. More specifically, it is preferable to use a device that can discharge a sample having a capacitance of 170 pF from a distance of 50 mm and discharge the charged voltage of the sample from 3 kV to 0 kV within 3 seconds.

  As the post-curing treatment, methods such as active energy ray irradiation treatment such as heat treatment, ultraviolet (UV) irradiation treatment, and radiation (EB) irradiation treatment are used. Regarding the easy adhesion treatment, the same one as the pretreatment device can be used. As the smoothing treatment, after the fiber layer is formed on the base web, it is passed through the nip of the roll, or the fiber layer on which the web is formed is applied to the heated mirror surface and dried, or the formed fiber. It is possible to take a means such as compression treatment in the vicinity of the surface of the layer.

  The present invention will be specifically described below with reference to examples. Moreover, unless otherwise indicated, the part in a sentence shows a mass part. Table 1 shows the results of Examples and Comparative Examples.

<Example 1>
Using a 10% aqueous solution (conductivity 100 μS / cm, surface tension 48 dyne / cm) of polyvinyl alcohol (PVA117: Kuraray Co., Ltd.) as the polymer material solution, a high-quality paper is produced by a web manufacturing apparatus (using a spinning head A) described later. As a base web, a fine fiber layer was formed on the surface. The speed of the substrate web (collector part) was 0.5 m / min, the nozzle voltage was 80 kV, and the auxiliary electrode voltage was 75 kV.
At this time, the upper limit of the solution supply rate at which the fiber layer was formed without any problem was 19 cc / min. The average fiber diameter was 0.4 μm.

<Example 2>
As the polymer material solution, an aqueous solution (conductivity 180 μS / cm, surface tension 40 dyne / cm) obtained by adding 50 parts by mass of polyethylene glycol (molecular weight: 500,000) to 50 parts by mass of the aqueous polyvinyl alcohol solution used in Example 1 was used. In the same manner as in Example 1, a fine fiber layer was formed on the surface of a fine paper as a dough web. The speed of the substrate web (collector part) was 0.5 m / min, the nozzle voltage was 80 kV, and the auxiliary electrode voltage was 70 kV.
At this time, the upper limit of the solution supply rate at which the fiber layer was formed without any problem was 18 cc / min. The average fiber diameter was 0.3 μm.

<Example 3>
A fine fiber layer was formed under the same conditions as in Example 1 except that the nozzle voltage was 80 kV and the auxiliary electrode voltage was 40 kV.
At this time, the upper limit of the solution supply rate at which the fiber layer was formed without any problem was 21 cc / min. The average fiber diameter was 0.4 μm.

<Example 4>
A fine fiber layer was formed under the same conditions as in Example 1 except that the nozzle voltage was 60 kV and the auxiliary electrode voltage was 15 kV.
At this time, the upper limit of the solution supply rate at which the fiber layer was formed without any problem was 18 cc / min. The average fiber diameter was 0.4 μm.
However, since a phenomenon that a part of the formed fibers adheres to the auxiliary electrode occurs, continuous operation for a long time cannot be performed.

<Example 5>
A fine fiber layer was formed under the same conditions as in Example 1 except that the spinning head B was used.
At this time, the upper limit of the solution supply speed at which droplet-like particles were mixed with the fiber and the fiber layer was formed without any problem was 8 cc / min. The average fiber diameter was 0.4 μm.

<Comparative Example 1>
The auxiliary electrode and the auxiliary power source were removed from the spinning head portion of the web manufacturing apparatus, and a fiber layer was formed under the same conditions as in Example 1.
When the nozzle voltage was 80 kV and the solution supply rate was 10 cc / min, a liquid pool was formed at the tip of the nozzle and dropped on the collector. Further, at the supply speed of 3 cc / min, the liquid did not drop, but instability such as vibration occurred in the jet. Although a fiber layer having an average fiber diameter of 0.3 μm was formed, many ball-shaped defects occurred.

<Web manufacturing equipment>
(1) Structure of the entire apparatus A spinning head having a nozzle and a removable auxiliary electrode (refer to (2) for details), a power source for applying voltage to the nozzle and the auxiliary electrode, and a tank of liquid polymer material And a tube for connecting a tank and a nozzle to supply a polymer material, and the polymer material is supplied by a pressure pump. Note that the voltage applied to the nozzle and the auxiliary electrode and the supply rate of the polymer substance can be variably controlled. The collector section is a belt roll whose speed can be adjusted.
(2) Spinning head structure 1: Spinning head A
Nozzles with an inner diameter of 0.2 mm and an outer diameter of 0.6 mm and a length of 30 mm were arranged in the spinning head as 56 matrixes of 7 × 8 at intervals of 50 mm. At that time, adjacent rows were arranged with a half-pitch shift.
The auxiliary electrode was formed by combining metal plates having a thickness of 1 mm and a width of 40 mm in a rhombus lattice so that the metal plate passes through the midpoint between the nozzles (see FIG. 5). The tip of the metal plate protruded 10 mm from the tip of the nozzle so as to cover the nozzle. The distance between the nozzle and the auxiliary electrode was 21.6 mm or more.
2: Spinning head B
The auxiliary electrode has the same configuration as the spinning head A, except that a metal plate having a thickness of 1 mm and a width of 20 mm is used in combination with a rhombus lattice, and the tip of the nozzle protrudes 10 mm from the auxiliary electrode. It was.
(3)

  From these results, it is clear that the embodiment of the present invention using the auxiliary electrode has drastically improved the production speed as compared with the conventional one.

1 is a schematic view of a web manufacturing apparatus according to the present invention. It is this other schematic of the web manufacturing apparatus of this invention. It is sectional drawing of the nozzle and auxiliary electrode of this invention. It is a top view of the nozzle and auxiliary electrode of the present invention. It is another top view of the nozzle and auxiliary electrode of this invention. It is this other schematic of the web manufacturing apparatus of this invention. It is this other schematic of the web manufacturing apparatus of this invention. 1: tank, 2: pump, 3: nozzle, 4: spinning head unit, 5: supply control system, 6: insulation unit, 7: auxiliary electrode, 8: collector unit, 9: main power source, 10: auxiliary power source, 11 :cell

Claims (7)

  Web production by electrospinning method having spinning head unit having nozzle for injecting polymer material, collector unit for collecting polymer material ejected from nozzle, and power supply for supplying voltage between said nozzle and collector unit In the apparatus, a web manufacturing apparatus having a plurality of nozzles and auxiliary electrodes existing between the nozzles in a spinning head unit, wherein the nozzles and the auxiliary electrodes can have different potentials.   The web manufacturing apparatus according to claim 1, wherein the potential applied to the auxiliary electrode is 50.0 to 99.9% of the potential with respect to the collector portion of the nozzle.   The web manufacturing apparatus according to claim 1, wherein the nozzle is surrounded by an auxiliary electrode.   The web manufacturing apparatus according to claim 1, wherein the auxiliary electrode forms a lattice-like cell, and a nozzle is disposed in the cell.   The web manufacturing apparatus according to claim 1, wherein the tip of the auxiliary electrode is the same as the tip of the nozzle or protrudes from the tip of the nozzle.   The web manufacturing apparatus according to any one of claims 1 to 5, wherein a distance between the nozzle and the auxiliary electrode is 10 to 50% of a distance between the nozzle tip and the collector portion. The web manufacturing apparatus according to claim 1, wherein an outer diameter of the nozzle is 2 mm or less, an inner diameter is 1 mm or less, and a length is 10 times or more of the outer diameter.

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