JP2006045758A - Non-woven fabric containing soft cell fibers and synthetic fibers - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonwoven fabric having compactibility, oil absorption and fat absorption superior to those of a conventional nonwoven fabric, and further having good touch feeling and excellent piercing strength. <P>SOLUTION: The nonwoven fabric comprises a fiber obtained from a parenchyma cell of a plant, and a synthetic fiber. The parenchyma cell is preferably derived from a sugar beet. In another embodiment, the parenchyma cell is preferably derived from a sugarcane. The fiber obtained from the parenchyma of the plant is preferably fibrillated so that the suspension stability may be ≥50%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nonwoven fabric containing at least fibers obtained from plant parenchyma cells and synthetic fibers.

  Fibers obtained from plants are used in large quantities in paper, pulp and clothing applications, but most of the fibers are derived from elongated fiber cells having cell walls composed of strong secondary walls. On the other hand, parenchymal cells in which the secondary wall is not developed cannot be used for the same purpose as conventional fiber cells because the cell walls are weak and there are many square cells.

  The soft tissue in which soft cells have gathered is abundant in fruits and stems, and is abundant in juice squeezed from fruits and sugar cane squeezed from sugar cane and sugar beet. However, many of these squeezes are often disposed as agricultural waste or industrial waste, and there are few cases where they are effectively used.

  Several methods have been proposed for effectively using the squeezed rice cake of industrial plants, and a method of using the squeezed rice wine for fermentation for a certain period of time, drying and crushing it and using it as livestock feed (for example, Patent Document 1). And a method of burning and carbonizing okara which is a squeezed soybean of soybean, and using it as a filtering agent and a filter aid as powder or granules (see, for example, Patent Document 2), inoculating koji mold on okara Examples include a method of using the dried product as an additive for food (for example, see Patent Document 3).

  However, when it is used as an additive for feed or food, since the raw materials are limited in terms of ingredients, there is a problem that it can be applied only to specific things such as wine squeezed and okara. In that respect, carbonized filter media and filter aids have few restrictions on raw materials, but on the contrary, there are many materials that can be used as raw materials, but it is efficient to deliberately carbonize a material with a high water content such as squeezed rice cake. It is bad and is considered inappropriate as a raw material.

  Conventionally, non-woven fabrics mainly composed of synthetic fibers have been filed as cosmetic degreasing sheets (for example, Patent Document 4), but these non-woven fabrics have insufficient sebum absorbability and are soft to the touch. There was a problem of being bad.

  In recent years, heat resistance such as reflow heat resistance is one of the characteristics required for electrochemical devices. Therefore, a separator with excellent heat resistance is used as the separator incorporated in the electrochemical element. For example, an electrolytic capacitor using a separator made of an aromatic polyamide fiber (for example, see Patent Documents 5 and 6), an electrolytic capacitor using a separator having a polyamide fiber as a main fiber (for example, see Patent Document 7), etc. Can be mentioned. Research and development for increasing the capacity of these electrochemical devices are actively conducted, and many improvements of electrodes and electrolytes have been made. In the case of a separator, it has been found that the thickness should be as thin as possible.

However, since these separators are made of synthetic fibers having almost no bonding force, mechanical strength such as tensile strength and puncture strength is weak, and it has been difficult to form a thin film. Moreover, since the nonwoven fabric which consists of these synthetic fibers has few affinity with electrolyte solution, there existed a tendency for internal resistance to become high.
JP-A-2002-171916 (pages 1 and 2) Japanese Patent Laid-Open No. 11-076813 (pages 1 and 2) JP-A-5-068503 (pages 1 to 6) JP 2001-286411 A JP-A-1-278713 JP-A-2-20012 JP 2002-198263 A

  The present invention has been made in view of the above circumstances, and effectively utilizes fibers obtained from parenchyma cells contained in squeezed straw that is often disposed of as industrial waste.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that fibers obtained from plant parenchyma cells, particularly the fibrillated fibers, are extremely thin and minute, and therefore have a very specific surface area. It is large and has excellent strength development ability due to hydrogen bonding even after drying. By including such soft cell fibers and synthetic fibers, it is excellent in denseness, oil absorption, and oil absorption, has good touch, and has excellent puncture strength. The present inventors have found that a non-woven fabric can be realized and have arrived at the present invention.

  That is, the present invention is a nonwoven fabric containing at least fibers obtained from plant parenchyma cells and synthetic fibers.

  In the present invention, the parenchyma cells are preferably derived from sugar beet or sugar cane that can be industrially mass-produced. By obtaining fibers from sugar beet and sugarcane juice cells generated in the sugar industry, it is possible to stably produce a large amount of fibers of a certain quality.

  In the present invention, the suspension stability of fibers obtained from plant parenchymal cells is preferably fibrillated to 50% or more.

  The present invention is a degreased sheet comprising a nonwoven fabric containing fibers obtained from plant parenchyma cells and synthetic fibers.

  The present invention is a separator made of a nonwoven fabric containing fibers obtained from plant parenchyma cells.

  In the separator of the present invention, it is preferable that at least a part of the synthetic fiber is a heat-resistant fiber having a melting point or a thermal decomposition temperature of 250 ° C. or higher and 700 ° C. or lower.

  In the separator of the present invention, it is preferable that at least a part of the synthetic fiber is fibrillated to a fiber diameter of 1 μm or less.

  According to the present invention, it is possible to obtain a non-woven fabric that is excellent in denseness, oil-absorbing property, and oil-absorbing property as compared with conventional non-woven fabrics, has a good touch and is excellent in puncture strength.

  In the present invention, fibers obtained from plant parenchymal cells (hereinafter referred to as parenchymal fibers) are a portion mainly composed of parenchymal cells present in plant stems, leaves, fruits, etc., treated with alkali, etc. It is a non-wood fiber that is mainly composed of the cellulose obtained and is insoluble in water. Parenchymal cells have the characteristic that secondary walls are not developed.

  In the present invention, in order to obtain plant parenchymal cells, the internal parenchyma of the stem, leaf mesophyll, fruits, etc. may be crushed, but industrially discharged from food processing factories, sugar factories, etc. It is optimal to use juice squeezed from fruit and squeezed squeezed from sugar beet, sugar cane and the like. For example, when using sugar beet squeezed rice cake, the crushed root can be squeezed and the remaining rice cake can be used as it is. When using sugarcane juice cake, a portion containing many parenchyma cells can be obtained by pulverizing bagasse, which is a sugarcane cake, to an appropriate size and passing it through a sieve having an opening of 1 to 2 mm.

  In the present invention, in order to obtain fibers from parenchymal cells, it is preferable to apply a pulping treatment when producing pulp from wood. For example, a kraft pulping method or a soda pulping method in which lignin is decomposed and removed by mixing and heating with an alkali such as caustic soda can be used. Detailed pulping conditions may be appropriately determined in view of the properties of the raw materials, the properties of the target fiber, the yield, and the like. After washing the alkali, bleaching is performed as necessary. Hydrogen peroxide, chlorine dioxide, sodium hypochlorite, oxygen, ozone, etc. can be used as the bleaching agent. After bleaching, it can be washed to obtain a fiber suspension.

  The fiber obtained by the pulping treatment can be used as it is, but the fibrillation treatment is preferable because the specific surface area is increased and the uniformity is increased. For fibrillation treatment, refiner, beater, mill, grinding device, rotary blade homogenizer that applies shear force with high-speed rotary blade, shear between cylindrical inner blade rotating at high speed and fixed outer blade Double-cylindrical high-speed homogenizer that generates force, ultrasonic crusher that is refined by ultrasonic impact, a pressure difference of at least 3000 psi is applied to the fiber suspension, and a small-diameter orifice is passed to increase the speed. A high-pressure homogenizer or the like that applies a shearing force or a cutting force to the fibers by colliding and rapidly decelerating can be used.

  A preferable standard for fibrillation of parenchymal fibers is a suspension stability of 50% or more. Here, the suspension stability of 50% or more means that the suspension below the settling surface of the fiber when a fiber suspension having a concentration of 0.1% by mass is placed in a graduated cylinder or the like and allowed to stand for 24 hours. The volume of is 50% or more of the total volume. This suspension stability can also be interpreted as dispersibility, and it can be said that the higher the dispersibility of the fibers and the more uniform the suspension, the higher the suspension stability. This suspension stability is related to the size of the fiber, and the more fibrillated, the higher the suspension stability. If the suspension stability is less than 50%, uneven distribution in the nonwoven fabric tends to occur, and as a result, formation of hydrogen bonds between the fibrils is weak and sufficient characteristics may not be obtained.

  Suspension stability of 50% or more can be achieved by optimizing the processing conditions using a refiner, beater, mill, attritor, rotary blade homogenizer, high-speed homogenizer, high-pressure homogenizer, or the like.

  Synthetic fibers contained in the wet nonwoven fabric of the present invention include polyolefin, polyester, acrylic, polyamide, polyethersulfone (PES), polyvinylidene fluoride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, carbon, graphite, phenol resin, Examples thereof include heat-resistant fibers having a melting point or thermal decomposition temperature of 250 ° C. or higher and 700 ° C. or lower, and single fibers and composite fibers made of synthetic biodegradable fibers typified by polylactic acid. A combination of the above may be used.

  The fiber length of the synthetic fiber used in the present invention is preferably 0.1 mm or more and 20 mm or less, and more preferably 1 mm or more and 10 mm or less. If the fiber length is less than 0.1 mm, it is easy to fall off, and if it is 20 mm or more, the fibers tend to get entangled and become lumpy, resulting in uneven thickness. The average fiber diameter is preferably 0.0002 μm or more and 30 μm or less, and more preferably 0.01 μm or more and 20 μm or less. The fineness is preferably 0.0001 dtex or more and 5 dtex or less, and more preferably 0.005 dtex or more and 3 dtex or less. If the average fiber diameter is 0.01 μm, particularly less than 0.0002 μm, or the fineness is less than 0.005 dtex, particularly less than 0.0001 dtex, the fibers tend to be too thin to form the basic skeleton of the wet nonwoven fabric. When the average fiber diameter is larger than 20 μm, particularly larger than 30 μm, or when the fineness is larger than 3 dtex, especially larger than 5 dtex, the wet nonwoven fabric tends to be uneven.

  The cross-sectional shape of the synthetic fiber used in the present invention may be any of a circular shape, an elliptical shape, a rectangular shape, a rectangular shape, a star shape, a Y shape, and other irregular shapes.

  In the separator of the present invention, the plant parenchymal fibers and the synthetic fibers are entangled with each other, whereby a higher tensile strength and puncture strength than those obtained with the parenchymal cell fibers alone or the synthetic fibers alone can be obtained.

  As the heat-resistant fiber having a melting point or thermal decomposition temperature of 250 ° C. or higher and 700 ° C. or lower in the present invention, wholly aromatic polyamide, wholly aromatic polyester, wholly aromatic polyester amide, wholly aromatic polyether, wholly aromatic polycarbonate, Totally aromatic polyazomethine, polyphenylene sulfide (PPS), poly-p-phenylenebenzobisthiazole (PBZT), poly-p-phenylenebenzobisoxazole (PBO), polybenzimidazole (PBI), polyetheretherketone (PEEK) , Polyamideimide (PAI), polyimide, polytetrafluoroethylene (PTFE), and the like. These may be used alone or in combination of two or more. PBZT may be either a transformer type or a cis type. Some aromatic polyamides and aromatic polyesters that are not wholly aromatic have a melting point or a thermal decomposition temperature of 250 ° C. or higher depending on the type and composition ratio of the monomers, and these can be used. Here, the aromatic that is not wholly aromatic refers to an aromatic chain having a part of the main chain, for example, a fatty chain. Among these, preferred are wholly aromatic polyamides which are easily fibrillated due to liquid crystallinity, particularly para wholly aromatic polyamides and wholly aromatic polyesters.

  Examples of wholly aromatic polyamides include poly-p-phenylene terephthalamide, poly-p-benzamide, poly-p-amide hydrazide, and poly-p-phenylene terephthalamide-3,4-diphenyl ether terephthalamide. It is not limited.

  The wholly aromatic polyester is synthesized by combining monomers such as aromatic diol, aromatic dicarboxylic acid, and aromatic hydroxycarboxylic acid and changing the composition ratio. For example, although the copolymer of p-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid is mentioned, it is not limited to this.

  Examples of the synthetic biodegradable fiber in the present invention include poly (α-hydroxy acid) such as polyglycolic acid and polylactic acid, and copolymers having these as main repeating units. Further, poly (ω-hydroxyalkanoate) such as poly (ε-caprolactone) and poly (β-propiolactone), poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3 Poly (β-hydroxyalkanoates) such as hydroxycapronate, poly-3-hydroxyheptanoate, poly-3-hydroxyoctanoate, and repeating units thereof with poly-3-hydroxyvalerate or poly And a copolymer with a repeating unit of -4-hydroxybutyrate.

  Examples of polyalkylene alkanoates comprising a condensation polymer of glycol and dicarboxylic acid include polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, poly Examples include butylene sebacate, polyhexamethylene sebacate, polyneopentyl oxalate, or a polyalkylene alkanoate copolymer having these as main repeating units.

  In the present invention, it is preferable that at least a part of the synthetic fiber is fibrillated to a fiber diameter of 1 μm or less (hereinafter referred to as fibrillated fiber). Here, the fibril refers to a fiber that has a portion that is very finely divided mainly in a direction parallel to the fiber axis, and at least a portion of which has a fiber diameter of 1 μm or less. US Pat. No. 5,833,807 The manufacturing method and shape are different from the fibrid as specified in the specification and US Pat. No. 5,026,456. The fibrils in the present invention preferably have a length / width aspect ratio in the range of 20: 1 to 100,000: 1 and a Canadian standard freeness in the range of 0 ml to 500 ml. Furthermore, it is preferable that the weight average fiber length is in the range of 0.2 mm or more and 2 mm or less. Moreover, in this invention, you may contain a fibrid.

  The fibrillated fiber in the present invention is produced using a high-pressure homogenizer, a homogenizer, a refiner, a beater, a mill, a grinding device, or the like.

  The nonwoven fabric of the present invention may contain fibers such as solvent-spun cellulose, regenerated cellulose, and natural cellulose as necessary, in addition to plant soft cell fibers and synthetic fibers. These fibers may be pulped or fibrillated. Also, glass, micro glass, rock wool, alumina, alumina / silica, zirconia, tyranno, silicon carbide, potassium titanate, alumina whisker, aluminum borate whisker, stainless steel, copper, other metals, composites of these, etc. It may contain inorganic fibers or inorganic substances.

  The nonwoven fabric in the present invention is produced by a wet papermaking method. For the preparation of the raw material slurry, a fiber raw material and, if necessary, a dispersant, a thickener and the like are appropriately added to adjust the solid content concentration to about 1% by mass to 0.001% by mass. This raw material slurry is further diluted to a predetermined concentration and sent to a paper machine for wet papermaking. As the paper machine, a circular paper machine, a long paper machine, a short paper machine, an inclined paper machine, a combination paper machine in which the same or different types of paper machines are combined, and the like are used.

  Nonwoven fabrics are used for clothing (skin, gloves, hats, etc.), protective (protective clothing, safety shoes, etc.), medical (surgical clothes, masks, etc.), construction (roofing, wall coverings, etc.), civil engineering (Drain materials, water shielding sheets, etc.), vehicles (floor mats, ceiling molding materials, etc.), sanitary items (diapers, hand towels, degreasing sheets, etc.), furniture / interior (carpets, wallpaper, etc.), wipers ( Wipers, wet wipers, etc.), filters (air filters, liquid filters, etc.), bedding (futons, sheets, etc.), agriculture / horticulture (plastic house sheets, nursery sheets, etc.), leather (artificial leather base materials) , Synthetic leather base materials), other household materials (storage bags, chemical cloths, tea bags, etc.), and other industrial materials (abrasives, electrical element separators, oil absorbing materials, etc.) It has been. The nonwoven fabric of the present invention can be used for any of these applications.

  Since the nonwoven fabric of the present invention is excellent in oil absorbency and excellent in touch, it is particularly preferable to use it as a cosmetic oil removing sheet for absorbing human sebum. When using the nonwoven fabric of this invention as a degreasing sheet, although thickness does not have a restriction | limiting in particular, 10-100 micrometers is preferable and 15-50 micrometers is more preferable. If the thickness is less than 10 μm, the sheet may be too thin and may be torn. If the thickness is more than 100 μm, the sheet becomes non-uniform, and the sheet tends to be stiff or uncomfortable. The content of the soft cell fibers is preferably 3% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less with respect to the nonwoven fabric. If the content of the soft cell fibers is less than 3% by mass with respect to the nonwoven fabric, the touch may be poor, or the oil absorption may be insufficient. On the other hand, when it exceeds 90 mass%, the space | gap of a sheet | seat becomes inadequate and there exists a possibility of impairing a fat-absorbing property.

  The nonwoven fabric of the present invention is preferably used for an electrochemical device separator because it has excellent puncture strength, denseness, and electrolyte compatibility. The electrochemical element in the present invention is a manganese dry battery, alkaline manganese battery, silver oxide battery, lithium battery, lead storage battery, nickel-cadmium storage battery, nickel-hydrogen storage battery, nickel-zinc storage battery, silver oxide-zinc storage battery, lithium ion battery. , Lithium polymer battery, various gel electrolyte batteries, zinc-air storage battery, iron-air storage battery, aluminum-air storage battery, fuel battery, solar battery, sodium sulfur battery, polyacene battery, electrolytic capacitor, electric double layer capacitor and the like. The electrode of the electric double layer capacitor may be a combination of a pair of electric double layer electrodes, one of which is an electric double layer electrode and the other is a redox electrode. The electrolyte includes an aqueous solution in which an ion dissociable salt is dissolved, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), acetonitrile (AN), γ-butyrolactone (BL ), Dimethylformamide (DMF), tetrahydrofuran (THF), dimethoxyethane (DME), dimethoxymethane (DMM), sulfolane (SL), dimethyl sulfoxide (DMSO), ethylene glycol, propylene glycol, etc. Although what melt | dissolved salt, an ionic liquid (solid molten salt), etc. are mentioned, It is not limited to these. In the case of an electrochemical element that can use both an aqueous solution system and an organic solvent system, an organic solvent system is preferred because the aqueous solution system has a low withstand voltage. Instead of the electrolytic solution, a conductive polymer film such as polypyrrole, polythiophene, polyaniline, polyacetylene, and derivatives thereof may be used.

  When the nonwoven fabric of the present invention is used as a separator, the thickness of the separator is not particularly limited, but is preferably 10 μm to 100 μm, and more preferably 20 μm to 60 μm. If it is less than 10 μm, it is difficult to obtain sufficient puncture strength. If it is thicker than 100 μm, for example, the electrode area that can be accommodated in an electrochemical element such as a secondary battery or an electric double layer capacitor is reduced, and the capacity of the electrochemical element is reduced. End up. The content of the soft cell fibers is preferably 3% by mass or more and 80% by mass or less, and more preferably 10% by mass or more and 60% by mass or less with respect to the nonwoven fabric. If the content of the soft cell fiber is less than 3% by mass with respect to the nonwoven fabric, the affinity with the electrolytic solution and the mechanical strength are likely to be insufficient, and the defect rate of the electrochemical device may be increased. On the other hand, when it is more than 80% by mass, the porosity of the nonwoven fabric is lowered, the electrolytic solution retention becomes insufficient, and the internal resistance may be increased.

  The separator of the present invention is subjected to processing such as calendaring, thermal calendaring, and heat treatment as necessary. In the case of heat treatment, the treatment is preferably performed at a temperature of 150 ° C. to 280 ° C. If it is less than 150 ° C., heat treatment tends to be insufficient, and if it is higher than 280 ° C., heat shrinkage tends to occur.

<Parallel cell fiber 1>
A commercially available beet pulp consisting of sugar beet squeezed koji was put into a 10 L autoclave. Caustic soda was mixed so that the liquid ratio was 4 and the effective alkali addition rate was 11 to 14%, and the mixture was treated under the conditions of a holding temperature of 120 ° C. and a holding time of 30 minutes. After washing by filtration, the sample concentration was adjusted to 8%, sodium hypochlorite was added to the sample so that the effective chlorine concentration was 2%, stirred, bleached at room temperature for 8 hours, and then washed by filtration. As a result, parenchymal cell fibers derived from sugar beet parenchyma cells were obtained. This was adjusted to 0.1% by mass, placed in a 100 mL measuring cylinder and allowed to stand, and the sedimentation volume of the parenchyma fibers after 24 hours was measured. As a result, the suspension stability was 15%. Hereinafter, this is referred to as parenchymal fiber 1 or J1.

<Parus cell fiber 2>
The bagasse consisting of sugar cane squeezed rice cake was crushed and passed through a sieve having an opening of 1 mm, and the portion passing through the sieve was collected. This was bleached and washed in the same manner as in <Parus cell 1> to obtain parenchyma fibers derived from sugar cane parenchyma. This was adjusted to 0.1% by mass, placed in a 100 mL graduated cylinder and allowed to stand, and the sedimentation volume of the parenchyma fibers after 24 hours was measured. As a result, the suspension stability was 11%. Hereinafter, this is referred to as parenchymal fiber 2 or J2.

<Fibrilized parenchyma cell fiber 1>
The fibrillated parenchymal fiber 1 is treated with a 1 L suspension at 10,000 rpm for 1 minute using a rotating blade homogenizer (Osterizer, manufactured by Osterizer Co., Ltd.). Was made. This was adjusted to 0.1% by mass, placed in a 100 mL measuring cylinder and allowed to stand, and the sedimentation volume of fibrillated parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 46%. . Hereinafter, this is referred to as fibrillated parenchymal cell fiber 1 or FBJ1.

<Fibrillated parenchyma cell fiber 2>
The soft cell fiber 1 was made into a 1% by mass suspension, and 1 L of the suspension was treated at 15700 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer). Next, using a high-pressure homogenizer (manufactured by Niro Soabi), 1 L of the suspension was circulated at a pressure of 50 MPa for 45 seconds to prepare fibrillated parenchyma fibers. This was adjusted to 0.1% by mass, placed in a 100 mL graduated cylinder and allowed to stand, and the sedimentation volume of the fibrillated parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 50.5%. there were. Hereinafter, this is referred to as fibrillated parenchymal fiber 2 or FBJ2.

<Fibrilized parenchyma fiber 3>
The soft cell fiber 1 was made into a 1% by mass suspension, and 1 L of the suspension was treated at 15700 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer). Next, using a high-pressure homogenizer (manufactured by Niro Soabi), 1 L of the suspension was circulated at a pressure of 50 MPa for 5 minutes to prepare fibrillated parenchyma fibers. This was adjusted to 0.1% by mass, placed in a 100 mL measuring cylinder and allowed to stand, and the sedimentation volume of fibrillated parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 100%. . Hereinafter, this is referred to as fibrillated parenchymal fiber 3 or FBJ3.

<Fibrillated parenchyma fiber 4>
The soft cell fiber 1 was made into a 1% by mass suspension, and 1 L of the suspension was treated at 15700 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer). Subsequently, it processed using the single disc refiner and produced the fibrillated parenchyma fiber. This was adjusted to 0.1 mass%, placed in a 100 mL measuring cylinder and allowed to stand, and the sedimentation volume of fibrillated parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 90%. . Hereinafter, this is referred to as fibrillated parenchymal fiber 4 or FBJ4.

<Fibrillated parenchyma fiber 5>
The soft cell fiber 2 was made into a 1% by mass suspension, and 1 L of the suspension was treated at 15700 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer). Next, using a high-pressure homogenizer (manufactured by Niro Soabi), 1 L of the suspension was circulated at a pressure of 50 MPa for 10 minutes to prepare fibrillated parenchyma fibers. This was adjusted to 0.1% by mass, placed in a 100 mL measuring cylinder and allowed to stand, and the sedimentation volume of fibrillated parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 100%. . Hereinafter, this is referred to as fibrillated parenchymal fiber 5 or FBJ5.

<Fibrylated heat-resistant fiber 1>
Para-type wholly aromatic polyamide (fineness: 1.7 dtex, fiber length: 3 mm, thermal decomposition temperature: 550 ° C.) is dispersed in water to an initial concentration of 5 mass%, and repeatedly beaten 15 times using a double disc refiner. A fibrillated para-type wholly aromatic polyamide fiber having a weight average fiber length of 1.25 mm was prepared. Hereinafter, this is referred to as fibrillated heat resistant fiber 1 or FB1.

<Fibrylated heat-resistant fiber 2>
The fibrillated heat-resistant fiber 1 was repeatedly beaten 25 times with a high-pressure homogenizer under the condition of 50 MPa to produce a fibrillated para-type wholly aromatic polyamide fiber having a weight average fiber length of 0.61 mm. Hereinafter, this is referred to as fibrillated heat resistant fiber 2 or FB2.

<Fibrylated heat-resistant fiber 3>
A wholly aromatic polyester (fineness: 1.7 dtex, fiber length: 3 mm, melting point: 320 ° C.) is dispersed in water to an initial concentration of 5% by mass and repeatedly beaten 15 times using a double disc refiner, and then a high-pressure homogenizer is used. The fibrillated wholly aromatic polyester fiber having a weight average fiber length of 0.35 mm was prepared by repeating the treatment 20 times under the condition of 50 MPa. Hereinafter, this is referred to as fibrillated heat resistant fiber 3 or FB3.

  According to the raw materials and blending amounts shown in Table 1, a raw slurry for wet nonwoven fabric was prepared. Here, “A1” in Table 1 is an acrylic fiber having a fineness of 0.08 dtex and a fiber length of 3 mm, “PET1” is a polyethylene terephthalate fiber having a fineness of 0.1 dtex and a fiber length of 3 mm, and “PET2” has a fineness of 0. 6 dtex, polyethylene terephthalate fiber having a fiber length of 5 mm, “PET3” is a polyester core-sheath composite fiber having a fineness of 1.1 dtex and a fiber length of 5 mm (core: polyethylene terephthalate, sheath: copolymer of polyethylene terephthalate and polyethylene isophthalate) ), “PA1” is an aromatic polyamide fiber having a fineness of 0.05 dtex and a fiber length of 3 mm (melting point 260 ° C.), “PA2” is a para-type wholly aromatic polyamide fiber having a fineness of 1.7 dtex and a fiber length of 5 mm, “PP1” "Is a polypropylene fiber having a fineness of 0.1 dtex and a fiber length of 3 mm," P E1 "a fineness 2.1Dtex, olefin core-sheath composite fibers of the fiber length of 5 mm (core: polypropylene, sheath: polyethylene) means.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to an Example.

Examples 1-28
Using the paper machine shown in Table 2, slurry papers 1 to 28 are wet-made, and super calender treatment is performed as necessary to adjust the thickness, and nonwoven fabrics 1 to 28 having the basis weight and thickness shown in Table 2 are obtained. Produced. In Table 2, “Yen / Yen” means a combination paper machine consisting of a circular paper machine and a circular paper machine, and “Yen / Tilt” means a combination paper machine consisting of a circular paper machine and an inclined paper machine. .

(Comparative Examples 1-6)
Using the paper machine shown in Table 2, slurry 29-34 is wet-papered, and super calender treatment is performed as necessary to adjust the thickness to produce nonwoven fabrics 29-34 having the basis weight and thickness shown in Table 2. did.

  The nonwoven fabrics 1 to 34 were measured by the following test methods, and the results are shown in Tables 2 to 4.

<Basis weight>
The basis weights of the nonwoven fabrics 1 to 34 were measured according to JIS C2301, and the results are shown in Table 2.

<Thickness>
The thicknesses of the nonwoven fabrics 1 to 34 were measured according to JIS C2301, and the results are shown in Table 2.

<Tensile strength>
Five or more separators 1 to 34 were cut into strips having a width of 50 mm and a length of 200 mm. The sample load of the desktop material testing machine (Orientec Co., Ltd., STA-1150) is clamped at 100 mm intervals on both ends of the sample, and the upper end is pulled up until it is cut at a constant speed of 100 mm / min. Table 2 shows the average value as the tensile strength.

<Puncture strength>
The separators 1 to 34 were cut into strips having a width of 50 mm. Attach a 1 mm diameter metal needle (Orientec Co., Ltd.) with a rounded end (curvature 1.6) to the desktop material testing machine (Orientec Co., Ltd. STA-1150) and place it on the sample surface. It was lowered until it penetrated at a constant speed of 1 mm / s at a right angle. The maximum load (g) at this time was measured and used as the puncture strength. The puncture strength was measured at five or more locations for one sample, and the lowest puncture strength among all the measured values is shown in Table 2. If the tip of the metal needle is not rounded, the angle of contact with the sample is shifted, and if the metal needle has burrs, the variation in the measured value increases, so it cannot be used for measurement.

<Defect rate>
Nonwoven fabrics 1 to 23 and 29 to 34 were used as separators. As the positive electrode and the negative electrode, activated carbon electrodes whose volume expands by about 5% by charging were used, a separator was stacked between the negative electrode and the positive electrode, and a spiral wound device was used to produce a spiral element. . The spiral element was housed in an aluminum case, and after the positive electrode lead and the negative electrode lead were welded to the positive electrode terminal and the negative electrode terminal attached to the case, the case was sealed leaving the electrolyte solution injection port. The entire case was heated to 200 ° C. for 15 hours to remove moisture contained in the electrodes and separator. This was allowed to cool to room temperature in a vacuum, and then an electrolytic solution was injected into the case, and the injection ports were sealed to prepare 100 electric double layer capacitors. As the electrolytic solution, a solution obtained by dissolving (C ₂ H ₅ ) ₃ (CH ₃ ) NBF ₄ in propylene carbonate so as to have a concentration of 1.5 mol / l was used. These electric double layer capacitors were charged to 2.7 V at a constant current of 20 A and then discharged at a constant current of 20 A. This charging / discharging was repeated 10 times, and the ratio of internal short-circuiting due to the breakage of the separator due to the volume expansion of the electrode was examined and set as the defective rate. The results are shown in Table 3.

<Internal resistance>
Using the nonwoven fabrics 1 to 23 and 29 to 34 as separators, 100 electric double layer capacitors were produced in the same manner as in <Defect rate>. These electric double layer capacitors were charged to 2.7 V at a constant current of 20 A, and then the internal resistance was calculated from the voltage drop immediately after the discharge when the constant current was discharged at 20 A. The results are shown in Table 3. . In addition, the electric double layer capacitor which the separator broke due to the volume expansion of the electrode and was internally short-circuited was excluded from the internal resistance measurement.

<Heat resistance>
Using the nonwoven fabrics 1 to 23 and 29 to 34, 100 electric double layer capacitors were produced in the same manner as in <Defect rate>. These electric double layer capacitors are placed in a reflow furnace set so that the surface temperature of the electric double layer capacitor is a maximum of 250 ° C., exposed to a temperature of 200 ° C. or higher for 60 seconds, and then the electric double layer capacitor is checked for any abnormality. I investigated. The case where the ratio of the electric double layer capacitor rupture or liquid leakage is 30% or more is x, the case where it is less than 30% is 10% or more, the case where it is less than 10%, but it occurs, the case where it does not occur at all The results are shown in Table 3.

<Absorption amount>
A mixed oil solution of castor oil 80% and benzyl alcohol 20% was prepared as pseudo sebum. 0.5 ml of the oil solution is placed on a printing roll of a printability tester (Ishikawajima Sangyo Co., Ltd., RI tester), and the roll is rotated to form an oil film uniformly, and then a roll nip pressure of 4.2 MPa is rotated. The oil film was transferred by rotating the nonwoven fabrics 24-34 between two printing rolls by rotating at a speed of 30 rpm. Table 4 shows the weight change of the nonwoven fabric before and after transferring the oil film, that is, the amount of oil transferred to the nonwoven fabric as the amount of oil absorption, and the ratio (%) to the paper weight before transfer. The larger this value, the better the oil absorption.

<Evaluation of touch>
The nonwoven fabrics 24-34 were applied to the cheeks of the panelists, and the touch was subjected to sensory evaluation in four stages according to the following criteria. The results are shown in Table 4.
◎… The skin is very good.
○ ... feels good.
Δ: Normal touch.
×: The skin is not split.
In this invention, the evaluation more than (circle) was set as the pass.

  As shown in Table 2, since the nonwoven fabrics 1 to 28 produced in Examples 1 to 28 contain plant parenchyma fibers and synthetic fibers, they have mechanical properties such as tensile strength and puncture strength even if they are thin. Excellent strength.

  Moreover, as shown in Table 2, when Examples 2, 4 to 6, 8, 10, and 11 are compared, the nonwoven fabrics 5, 6, 8, 10, and 11 containing fibrillated parenchymal fibers are fibrils. Tensile strength and puncture strength were superior to the non-woven fabrics 2 and 4 containing parenchymal cells.

  As shown in Table 3, the nonwoven fabrics 1 to 23 containing soft cell fibers and synthetic fibers are excellent in puncture strength and excellent in electrolyte solution compatibility even if they are thin. Both the defect rate and the internal resistance of the electric element comprising the separator were very low and excellent. From these results, the nonwoven fabric of the present invention is suitable as a separator.

  Since the nonwoven fabrics 1 to 21 contain heat resistant fibers having a melting point or a thermal decomposition temperature of 250 ° C. or higher and 700 ° C. or lower, they are also excellent in heat resistance. Furthermore, the nonwoven fabrics 12 to 15, 17, 19, 20 Contains heat-resistant fibers having a melting point or a thermal decomposition temperature of 250 ° C. or higher and 700 ° C. or lower, at least partly fibrillated to a fiber diameter of 1 μm or less, and thus more excellent in heat resistance and more suitable as a separator. It is.

  As shown in Table 4, since the nonwoven fabrics produced in Examples 22 to 28 contain plant parenchyma fibers and synthetic fibers, they are excellent in both oil absorbency and touch, so a cosmetic degreasing sheet It is suitable as.

  On the other hand, the non-woven fabrics 29 to 34 that do not contain plant parenchyma cells prepared in Comparative Examples 1 to 6 have low puncture strength and low electrolyte solution affinity. All of the resistances showed high values. From these results, the nonwoven fabrics 29 to 34 were not suitable as separators.

  Moreover, since the nonwoven fabrics 29 to 34 produced in Comparative Examples 1 to 6 did not contain plant soft cell fibers, they were poor in oil absorption and touch and were unsuitable as cosmetic degreasing sheets.

  Examples of utilization of the present invention include cosmetic degreasing sheets, electrochemical device applications that require low internal resistance, such as separators for electric double layer capacitors, electrolytic capacitors, lithium secondary batteries, and the like.

Claims (8)

  A nonwoven fabric containing at least fibers obtained from plant parenchyma cells and synthetic fibers.   The non-woven fabric according to claim 1, wherein the soft cells are derived from sugar beet.   The non-woven fabric according to claim 1, wherein the soft cells are derived from sugarcane.   The nonwoven fabric according to any one of claims 1 to 3, wherein the suspension stability of fibers obtained from plant parenchymal cells is fibrillated to 50% or more.   The degreasing sheet which consists of a nonwoven fabric in any one of Claims 1-4.   The separator which consists of a nonwoven fabric in any one of Claims 1-4.   The separator according to claim 6, wherein at least a part of the synthetic fiber is a heat-resistant fiber having a melting point or a thermal decomposition temperature of 250 ° C. or more and 700 ° C. or less.   The separator according to claim 6 or 7, wherein at least a part of the synthetic fiber is fibrillated to a fiber diameter of 1 µm or less.