JP2008027678A - Separator paper for alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide separator paper for an alkaline battery excellent in electrolyte retention for alkaline electrolyte, capable of preventing inner short circuiting in a battery with an excellent separating property, and thereby capable of improving battery capacity and battery life, as well as separator paper for an alkaline battery capable of exerting above characteristics even if it is used especially for a mercury-free alkaline battery. <P>SOLUTION: The separator paper for an alkaline battery contains a mercerized parenchyma cell fiber made by putting cellulose fiber obtained from a parenchyma cell structure of a plant under mercerizing treatment. A content of the mercerized parenchyma cell fiber is preferred to be 1 to 30% by mass, and a suspension stability of the mercerized parenchyma cell fiber is preferred to be 50% or more. Further, the paper is preferred to contain alkali-proof synthetic fiber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to separator paper for alkaline batteries such as alkaline manganese batteries, silver oxide batteries, nickel zinc batteries, and zinc air batteries.

  The characteristics required for separator paper for alkaline batteries such as alkaline manganese batteries, silver oxide batteries, nickel zinc batteries, and air zinc batteries are alkali resistance, electrolyte solution absorbability, and separation properties. Alkali resistance means that the separator does not undergo alteration or strength reduction with respect to an alkaline aqueous solution such as a potassium hydroxide aqueous solution used as an electrolytic solution. If the alkali resistance is insufficient, the battery reaction may be incomplete or an internal short circuit may occur between the battery electrodes. Moreover, electrolyte solution absorptivity is the characteristic which can fully contain electrolyte solution. If the electrolyte solution absorbency is low, the battery reaction is hindered, resulting in a problem that a large current, which is a characteristic of alkaline batteries, cannot be taken out. Furthermore, “separability” refers to a performance that can prevent the passage of an active material or a conductive material in an electrode even if it has fine pores. If the separation property is insufficient, conductive materials such as zinc oxide needle-like crystals (dendrites) pass through the separator and cause an internal short circuit.

  Conventionally, separator paper for alkaline batteries mainly composed of polyvinyl alcohol fiber, which is an alkali-resistant synthetic fiber, has been used. Various studies have been made in order to improve the electrolyte solution absorbability and the separation property. For example, separators for alkaline batteries that use polyvinyl alcohol fibers and hydrophilic fibers in combination to improve the electrolyte solution absorbency, and the fineness of polyvinyl alcohol fibers is specified to be 0.88 dtex or less to improve the separation property. Alkali battery separator paper and the like are known (for example, Patent Documents 1 and 2).

  In addition, for the purpose of low electrical resistance, denseness, and prevention of internal short circuit, CSF 510-720 ml of lightly refined mercerized wood kraft pulp mixed with synthetic fiber so as to be 50% by mass or more was obtained. Battery separator paper has been proposed (for example, Patent Document 3).

  In recent years, the use of mercury added to the negative electrode in order to suppress the self-discharge reaction of zinc from the viewpoint of environmental protection has been limited. However, since the low addition rate of negative electrode mercury brings about a phenomenon of dendrite miniaturization caused by the battery reaction, an internal short circuit of the battery is likely to occur. Furthermore, since the battery reaction is hindered as the amount of zinc oxide eluted into the electrolytic solution increases, the battery life tends to decrease. The conventional separator paper for alkaline batteries as described above cannot sufficiently cope with problems such as occurrence of internal short circuit and reduction in battery life.

  For this reason, various studies have been made to develop battery separator papers having even higher levels of separation and electrolyte absorption. At present, separator paper for alkaline batteries in which polyvinyl alcohol fiber is thinned to 0.33 dtex is also commercially available. However, if the polyvinyl alcohol fiber is made thin, the electrolyte solution absorbability is not sufficient, and a battery having a large capacity cannot be obtained.

Therefore, for the purpose of improving the separation property and the electrolyte solution absorption property, a battery separator paper formed by mixing a refined alkali-resistant cellulose fiber and a synthetic fiber such as a polyvinyl alcohol fiber has been proposed. However, it does not satisfy the requirements for high separation property and electrolyte solution absorbency required for mercury-free alkaline batteries (for example, Patent Documents 4 to 5).
Japanese Patent Publication No.53-11059 Japanese Patent Laid-Open No. 62-154559 JP 54-87824 A JP 2002-279957 A JP 2006-4844 A

  It is an object of the present invention to have excellent electrolyte retention with respect to an alkaline electrolyte and good separation properties, and can prevent the occurrence of an internal short circuit in a battery, thereby improving battery capacity and battery life. The present invention relates to separator paper for alkaline batteries. In particular, the present invention is to provide an alkaline battery separator paper that can exhibit the above-described characteristics even when used in a mercury-free alkaline battery.

In order to achieve the above object, the present invention provides
(1) Separator paper for alkaline batteries, characterized in that it contains mercerized parenchymal fibers obtained by mercerizing cellulose fibers obtained from plant parenchyma tissue;
(2) The separator paper for alkaline batteries according to (1) above, wherein the content of mercerized parenchyma fibers is 1 to 30% by mass,
(3) The separator paper for alkaline batteries according to (1) or (2) above, wherein the suspension stability of mercerized parenchymal fiber is 50% or more,
(4) The alkaline battery separator paper according to any one of the above (1) to (3), further comprising an alkali-resistant synthetic fiber.

  In the present invention, a separator cell for alkaline batteries contains mercerized parenchyma fibers obtained by mercerizing cellulose fibers (hereinafter referred to as parcel cell fibers) based on parenchyma cells contained in plants. It is what is done. Unlike cellulose fibers, which are made of pulp made from plant tissue, middle wood fibers, etc., and are made finer by operations such as refining, it uses the original fine structure of the soft cell fibers, making it extremely dense. Excellent separator paper for alkaline batteries can be obtained. Therefore, the effect of preventing an internal short circuit due to the contact of the bipolar active materials and an internal short circuit due to the outflow of the conductive zinc oxide crystal accompanying no addition of mercury is great. In addition, even if the alkaline battery separator paper is thinned, the soft cell fibers exhibit a separability, so that the active material filling amount can be increased. An alkaline battery having a battery capacity can be obtained.

  Further, mercerized parenchyma fibers themselves can absorb the electrolyte solution and contribute to conductivity. Therefore, the electrical resistance can be kept low although it is dense.

  Furthermore, when parcel fibers are converted into merceres, the fiber crystal structure changes from the cellulose I state to the cellulose II state, and the cross section of the entire parenchymal fibers changes from a flat shape to a circular shape. In the separator paper for alkaline batteries containing such a circular fiber, denseness is improved and ion conductivity is improved. Furthermore, since the soft cell fibers become harder due to the mercerization, the fibers are dispersed smaller when refined, and even if the degree of refinement is increased, it is difficult to increase the density, and the alkaline battery separator paper itself is crushed. It has the effect of becoming difficult. That is, when soft cell fibers are used in the form of merceres, ion conductivity can be maintained even at high density, and an internal short circuit can be prevented and electrical resistance can be reduced.

  The details of the separator paper for alkaline batteries of the present invention will be described.

  The parenchyma fiber according to the present invention is mainly composed of cellulose obtained by treating a portion mainly composed of parenchyma cells present in plant stems, leaves, fruits and the like with alkali, and is non-wood which is insoluble in water. Fiber. The parenchyma has the primary cell wall development and has a plant morphological feature that the secondary wall development is delayed compared to other fibers.

  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 fruits 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 a lot of parenchyma cells can be obtained by pulverizing bagasse, which is a juice cake, to an appropriate size and sieving it with an opening of 1 to 2 mm.

In the present invention, in order to obtain parenchymal fibers from parenchymal cells, it is preferable to apply a pulping treatment when producing pulp from wood. For example, a soda pulping method in which lignin is decomposed and removed by mixing and heating with an alkali such as sodium hydroxide 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.
The concentration of the alkaline solution is preferably 1 to 10% by mass in terms of solid content, and the liquid temperature is preferably 80 to 170 ° C. The treatment time is preferably 30 to 120 minutes. Next, after washing the alkali, a bleaching treatment is performed as necessary. Hydrogen peroxide, chlorine dioxide, sodium hypochlorite, oxygen, ozone, etc. can be used as a bleaching agent. After bleaching, a suspension of cellulose fibers can be obtained by washing, concentration, and the like. This soft cell fiber is a fiber mainly composed of a primary wall, and is suitable for a miniaturization treatment.

  The mercerization treatment according to the present invention refers to the treatment of soft cell fibers with an alkaline solution. As the alkaline solution, a sodium hydroxide solution, a potassium hydroxide solution, a lithium hydroxide solution, or the like can be used. The concentration of the alkaline solution is preferably 5 to 45% by mass in terms of solid content, and the liquid temperature during the mercerization treatment is preferably 0 to 40 ° C, more preferably 0 to 30 ° C. The treatment time is preferably 10 to 300 minutes. The parenchyma fibers are immersed in an alkaline solution to swell the fibers, and then washed well to obtain mercerized parenchyma fibers. By this treatment, hemicellulose that is easily disintegrated in the pulp can be removed, cellulose having high purity is obtained, and alkali resistance is generated. In addition, what was originally a crystal structure of cellulose I is modified to a crystal structure of cellulose II, and the cross-section of the flat cell-like fibers changes into a circular shape.

  The mercerized parenchyma fibers according to the present invention can be used as they are, but are preferred because they increase the specific surface area and increase the uniformity when subjected to a finer treatment. For refinement processing, refiner, beater, mill, grinding device, rotary blade homogenizer that gives shearing force by 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 the refinement treatment is a suspension stability of 50% or more. Here, the suspension stability of 50% or more means that when a 0.1% by mass suspension of mercerized parenchyma fibers according to the present invention is placed in a graduated cylinder or the like and allowed to stand for 24 hours, the sedimentation surface of the fibers. The volume of the lower suspension is 50% or more of the total volume of the suspension. 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 stable the suspension, the higher the stability of the suspension. If the suspension stability is less than 50%, the distribution state in the sheet paper layer formed from the fibers tends to be uneven, and as a result, the formation of hydrogen bonds between the fibers is weak and sufficient characteristics may not be obtained. is there.

  Further, if the suspension stability of mercerized parenchymal fibers is less than 50%, the fineness of the fibers is insufficient, and the denseness capable of preventing internal short circuit may be insufficient. With soft cell fibers having a suspension stability of less than 50%, the texture of the separator paper for alkaline batteries may become uneven.

  In the separator paper for alkaline batteries of the present invention, the content of mercerized soft cell fibers is 1 to 30% by mass, more preferably 5 to 20% by mass. If the content of mercerized parenchymal fibers exceeds 30% by mass, the drainage of the papermaking slurry may be significantly reduced, making papermaking difficult. In addition, if the content of mercerized parenchymal fibers is less than 1%, the effect of preventing internal short-circuiting is reduced, or the electrolyte retainability when incorporated in the battery becomes insufficient, and the internal resistance of the battery increases. There are things to do.

  In the separator paper for alkaline batteries of the present invention, the content of mercerized parenchyma fibers is effective in order to prevent internal short circuit effectively and to provide sufficient liquid retention so as to be compatible with the addition of mercury in alkaline batteries. The fineness is preferably 1 to 30% by mass and the fineness is 50% or more in terms of suspension stability. It is particularly preferable that the content is 5 to 20% by mass and the suspension stability is 50% or more.

  Further, as described above, the mercerized parenchymal fiber according to the present invention can be obtained by applying a mechanical shearing force to the parcel fiber after being subjected to the mercerization treatment, and then obtaining a fine particle. It can also be obtained by subjecting the cell fibers to a mercerization process after the cell fibers are refined. The suspension stability of the fine fibers can be appropriately adjusted even if the process order is changed by changing the treatment strength / treatment time during the refinement treatment and the treatment conditions for the mercerization treatment.

  As the alkali-resistant synthetic fiber according to the present invention, a fiber excellent in alkali resistance with little dissolution and shrinkage in an alkaline electrolyte is preferable. For example, examples of the composite fiber include polypropylene-polyethylene composite fiber, polypropylene-polyethylene vinyl acetate composite fiber, and polypropylene-polyethylene vinyl alcohol composite fiber. Examples of synthetic pulp include polypropylene synthetic pulp and polyethylene synthetic pulp. As the synthetic fiber, ordinary polypropylene fiber, polyethylene fiber, polyamide fiber, vinylon fiber, vinylon fiber, regenerated cellulose fiber, solvent-spun cellulose fiber, and the like are used. Usually, synthetic fibers have a drawback that it is difficult to absorb the electrolyte solution. However, in the separator paper for alkaline batteries of the present invention, since the mercerized soft cell fibers exhibit sufficient liquid absorbency, the synthetic fibers are blended. However, the effect that the internal resistance of the battery is difficult to increase is obtained.

  As the alkali-resistant synthetic fiber according to the present invention, those having a thin fiber diameter and a short fiber length are preferably used because they hardly cause pinholes and have a high dendrite preventing effect. The fineness is preferably 2.0 decitex or less and the fiber length is preferably 3 mm or less, and particularly preferably a synthetic fiber having a fiber diameter of 1 dtex or less and a fiber length of 1 mm to 2 mm. The cross-sectional shape of the synthetic fiber can be selected from various shapes such as a circular shape, an elliptical shape, a star shape, and a different shape.

  The separator paper for alkaline batteries in the present invention uses a circular paper machine, a long paper machine, a short paper machine, an inclined paper machine, a combination paper machine in which the same type or different types of paper machines are combined. Can be produced by a paper making method. For the preparation of the raw material slurry, a fiber raw material is appropriately added and adjusted to a desired solid content concentration. This raw slurry is further diluted to a predetermined concentration to make paper.

  The alkaline battery separator paper is preferably interposed between the positive electrode and the negative electrode in a thickness range of 15 μm to 120 μm. One separator paper for alkaline batteries may be used, or a plurality of separator papers may be used. When the thickness is less than 15 μm, the strength of the wet paper becomes low during manufacture, and it becomes easy to cut, which may make it difficult to manufacture separator paper for alkaline batteries. Also, the parenchyma fibers flow out through the papermaking net, and pinholes are generated in the separator paper for alkaline batteries, so that internal short circuit of the battery is likely to occur. When the thickness of the separator paper for alkaline batteries exceeds 120 μm, it is difficult to drain water from the papermaking net, and the wet paper may contain too much water, making it difficult to form a sheet.

  The air permeability of the separator paper for alkaline batteries of the present invention is preferably 10 minutes / 100 ml to 800 minutes / 100 ml. When the air permeability is less than 10 minutes / 100 ml, the effect of preventing internal short circuit of the battery tends to be insufficient. When the air permeability exceeds 800 minutes / 100 ml, the electrical resistance may increase and the high rate discharge characteristics may deteriorate.

  Various specific examples for producing the separator paper for an alkaline battery according to the present invention are shown below.

<Parallel cell fiber 1>
A commercially available beet pulp consisting of sugar beet squeezed koji was put into a 10 L autoclave. Sodium hydroxide was mixed so that the liquid ratio was 4 L / kg and the effective alkali addition rate (vs. parenchyma cells) was 12% by mass, 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% by mass, the mixture was 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.

<Mercelized soft cell fiber 1>
600 mass parts of 30 mass% sodium hydroxide solution was added with respect to 60 mass parts parenchymal fiber 1, and it hold | maintained at 25 degreeC for 3 hours. After dehydration, it was washed with water, further neutralized with a 1% by mass sulfuric acid solution, then washed again with water and filtered to obtain mercerized soft cell 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 mercerized parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 22%. . Hereinafter, this is referred to as mercerized parenchyma fiber 1 or MJ1.

<Mercelized soft cell fiber 2>
The mercerized soft cell fiber 1 was made into a 1% by mass suspension, and 1 L of the suspension was treated at 10,000 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer Co., Ltd.). Cell fibers were made. This was adjusted to 0.1 mass%, placed in a 100 mL graduated cylinder and allowed to stand, and the sedimentation volume of mercerized parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 55%. . Hereinafter, this is referred to as mercerized parenchyma fiber 2 or MJ2.

<Mercelized soft cell fiber 3>
The mercerized parenchyma 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 suspension was circulated at a pressure of 50 MPa for 5 minutes to produce fine parenchyma cell 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 mercerized parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 100%. . Hereinafter, this is referred to as mercerized parenchyma fiber 3 or MJ3.

<Mercelized parenchyma fiber 4>
The mercerized soft cell fiber 1 is made into a 1% by mass suspension, and 1 L of the suspension is treated at 7000 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer Co., Ltd.). Cell fibers were made. This was adjusted to 0.1% by mass, placed in a 100 mL graduated cylinder and allowed to stand, and the sedimentation volume of mercerized parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 47%. . Hereinafter, this is referred to as mercerized parenchyma fiber 4 or MJ4.

<Mercelized soft cell fiber 5>
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 treated at a pressure of 50 MPa for 45 seconds to produce a fine parenchyma cell fiber, and a 30 mass% sodium hydroxide solution was used as a solid. 10 times the amount of fiber was added, and held at 25 ° C. for 3 hours. After dehydration, it was washed with water, neutralized with sulfuric acid, washed with water and filtered several times to obtain mercerized soft cell 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 mercerized parenchymal fibers after 24 hours was measured. As a result, the suspension stability was 55%. It was. Hereinafter, this is referred to as mercerized parenchyma fiber 5 or MJ5.

<Parus 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 suspension was circulated at a pressure of 50 MPa for 45 seconds to produce fine parenchyma cell fibers. This was adjusted to 0.1% by mass, placed in a 100 mL graduated cylinder and allowed to stand, and as a result of measuring the sedimentation volume of the refined parenchyma fibers after 24 hours, the suspension stability was 50.5%. there were. Hereinafter, this is referred to as parenchymal fiber 2 or J2.

<Mercelized fine cellulose fiber 1>
600 parts by mass of a 30% by mass sodium hydroxide solution was added to 60 parts by mass of fine pulp derived from wood pulp (trade name: Celish KY-100G, manufactured by Daicel Chemical Industries), and the mixture was held at 25 ° C. for 3 hours. After dehydration, it was washed with water, further neutralized with a 1% by mass sulfuric acid solution, washed again with water and filtered to obtain mercerized cellulose fibers. Using a high-pressure homogenizer (manufactured by Niro Soabi), a 1% by mass suspension was circulated at a pressure of 50 MPa for 10 minutes to produce mercerized fine cellulose fibers. This was adjusted to 0.1% by mass, placed in a 100 mL graduated cylinder and allowed to stand, and the sedimentation volume after 24 hours was measured. As a result, the suspension stability was 55%. Hereinafter, this is expressed as mercerized fine cellulose fiber 1 or MC1.

<Mercelized fine cellulose fiber 2>
600 parts by mass of a 30% by mass sodium hydroxide solution was added to 60 parts by mass of commercially available bacterial cellulose (Natacoco, manufactured by Fujicco Co., Ltd.) and kept at 25 ° C. for 3 hours. After dehydration, it was washed with water, neutralized with a 1% by mass sulfuric acid solution, washed again with water and filtered to obtain mercerized bacterial cellulose. 1 L of a 1% by mass suspension was treated at 8000 rpm for 1 minute using a rotary blade homogenizer (Osterizer, manufactured by Osterizer) to produce mercerized fine cellulose fibers. This was adjusted to 0.1% by mass, placed in a 100 mL graduated cylinder and allowed to stand, and the sedimentation volume after 24 hours was measured. As a result, the suspension stability was 60%. Hereinafter, this is expressed as mercerized fine cellulose fiber 2 or MC2.

(Example 1)
15 parts by mass of mercerized soft cell fiber 2, 70 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are mixed and mixed The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 2)
1 part by mass of mercerized soft cell fiber 2, 84 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 3)
3 parts by mass of mercerized soft cell fiber 2, 77 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 20 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

Example 4
5 parts by mass of mercerized parenchyma fiber 2, 80 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 5)
20 parts by mass of mercerized soft cell fiber 2, 65 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 6)
30 parts by mass of mercerized parenchyma fiber 2, 60 parts by mass of vinylon fiber (1.1 dtex x 3 mm), 10 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex x 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 7)
40 parts by mass of mercerized soft cell fiber 2, 50 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 10 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 8)
15 parts by mass of mercerized soft cell fiber 1, 70 parts by mass of vinylon fiber (1.1 decitex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 decitex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

Example 9
15 parts by mass of mercerized soft cell fiber 3, 70 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 10)
15 parts by mass of mercerized parenchyma fiber 4, 70 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water are added and mixed, and the concentration The raw material was 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 11)
15 parts by mass of mercerized soft cell fibers 2, 70 parts by mass of polyethylene synthetic pulp, 15 parts by mass of polypropylene-polyethylene core-sheath composite fiber (0.77 dtex × 5 mm) and water were added and mixed, and the concentration was 1% by mass. Used as raw material. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

Example 12
15 parts by mass of mercerized soft cell fibers 2, 70 parts by mass of vinylon fibers (0.55 dtex × 2 mm), 15 parts by mass of polyvinyl alcohol powder and water were added and mixed to obtain a raw material having a concentration of 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Example 13)
5 parts by mass of mercerized parenchyma fibers 2 and 95 parts by mass of becered mercerized softwood pulp (1 ml) and water were added and mixed to obtain a raw material having a concentration of 1% by mass. This raw material was made with a long paper machine to obtain separator paper for an alkaline battery.

(Example 14)
Paper was made under the same conditions as in Example 2 except that the mercerized parenchymal fibers 2 were changed to mercerized parenchymal fibers 5 to obtain separator paper for alkaline batteries.

(Comparative Example 1)
85 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol binder fiber (1.1 dtex × 3 mm) and water were added and mixed to obtain a raw material having a concentration of 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Comparative Example 2)
To 30 parts by mass of unrefined mercerized hardwood wood pulp adjusted to CSF 690 ml with a pulverizer, 60 parts by mass of vinylon fiber (1.1 decitex × 3 mm), 10 parts by mass of polyvinyl alcohol binder fiber and water In addition, they were mixed to obtain a raw material having a concentration of 1% by mass. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Comparative Example 3)
60 parts by weight of vinylon fibers (1.1 decitex × 3 mm) and 10 parts by weight of polyvinyl alcohol fibers were added to 30 parts by weight (350 ml of CSF) of unrefined mercerized hardwood wood pulp to prepare raw materials. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Comparative Example 4)
60 parts by weight of vinylon fibers (1.1 decitex × 3 mm) and 10 parts by weight of polyvinyl alcohol fibers were added to 30 parts by weight (350 ml of CSF) of unrefined mercerized softwood wood pulp and used as raw materials. This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Comparative Example 5)
To 10 parts by mass of mercerized fine cellulose fiber 2, 75 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol fiber and water were added and mixed to obtain a raw material having a concentration of 1% by mass. . With this raw material, the freeness was too low to make paper with a circular net paper machine.

(Comparative Example 6)
To 15 parts by mass of mercerized fine cellulose fiber 1, 70 parts by mass of vinylon fiber (1.1 dtex × 3 mm), 15 parts by mass of polyvinyl alcohol fiber and water were added and mixed to obtain a raw material having a concentration of 1% by mass. . This raw material was paper-made with a circular paper machine to obtain a separator paper for an alkaline battery.

(Comparative Example 7)
Water was added to and mixed with 100 parts by mass of mercerized conifer wood pulp (CSF 1 ml) to obtain a raw material having a concentration of 1% by mass. This raw material was made with a long paper machine to obtain separator paper for an alkaline battery.

(Evaluation of separator paper for alkaline batteries)
The following evaluation was performed with respect to the separator paper for alkaline batteries obtained in the above Examples and Comparative Examples.
(1) Thickness (unit: μm): The thickness of the obtained separator paper was measured with a dial thickness gauge.
(2) Basis weight (unit: g / m ² ): Measured by a method according to JIS P 8124.
(3) Air permeability (unit: seconds / 100 ml): measured by a method according to JIS P 8117.
(4) Tensile strength (unit: kN / m): Measured by a method according to JIS P 8113.
(5) Electric resistance (unit: mΩ): Separation paper for alkaline batteries was inserted between platinum electrodes parallel at an interval of 3 mm, and the increase in electric resistance between the electrodes accompanying this insertion was taken as the electric resistance of the separator paper. . In addition, 40 mass% potassium hydroxide aqueous solution was used as electrolyte solution, and the electrical resistance between electrodes was measured using an ESR meter at a frequency of 1000 Hz.

  The results obtained by measuring the alkaline battery separator paper of each of the above Examples and Comparative Examples are shown in Table 1.

  The separator paper for alkaline batteries of Examples 1 to 7 containing mercerized parenchyma fibers was more air permeable than the separator paper for alkaline batteries of Comparative Example 1 not containing mercerized parenchyma fibers. Was confirmed to be high. While the denseness was increased, the electrical resistance of the alkaline battery separator paper containing mercerized parenchymal fibers was reduced, and it was confirmed that the mercerized parenchymal fibers had increased conductivity.

  The air permeability and electrical resistance are good in the battery separator paper of Examples 1 to 6 containing 1 to 30% by mass of mercerized soft cell fibers, and 5 to 20% by mass of mercerized soft cell fibers. The separator papers for alkaline batteries of Examples 1, 4, and 5 were particularly good. The separator paper for alkaline batteries of Example 7 containing 40% by mass of mercerized soft cell fibers had a non-uniform portion, showed a tendency to decrease air permeability and increase electrical resistance. . In Examples 2 and 3 in which the content of mercerized parenchymal fibers was less than 5%, the blending effect was weakened, the denseness was slightly lost, the amount of electrolyte retained was reduced, and the electrical resistance slightly increased.

  Examples 1 and 8 to 10 are separator papers for alkaline batteries in which the suspension stability of mercerized soft cell fibers is changed. In Example 8 in which the level of fineness was lowered and the suspension stability was 22%, there was a tendency for the denseness to decrease and the electrical resistance to increase. In Example 9 in which the level of refinement was increased and the suspension stability was 100%, the result was that the denseness was high and the electrical resistance was low.

  As shown in Examples 11 and 12, even when the type of the alkali-resistant synthetic fiber other than the mercerized soft cell fiber was changed, the denseness was increased and the electrical resistance was reduced.

  In Comparative Examples 2 and 3 in which ordinary hardwood wood pulp is mercerized, the air permeability is significantly smaller than those of various Examples and is insufficient. Comparative Example 4 used softwood bleached wood pulp that had been subjected to mercerization, but the results were similar.

  In Comparative Example 5 using mercerized bacterial cellulose, the freeness was too low to be suitable for sheeting, and separator paper for alkaline batteries could not be obtained.

  In Comparative Example 6, the mercerized soft cell fiber of Example 1 is changed to MC1 obtained by mercerizing fine cellulose derived from wood pulp. Compared with the separator paper for alkaline batteries of Example 1, the separator paper for alkaline batteries of Comparative Example 6 was inferior in denseness and electrical resistance.

  The separator paper for alkaline batteries containing 5% by mass of MJ2 of Example 13 has higher air permeability and lower electrical resistance than the separator paper for alkaline batteries made only of mercerized softwood wood pulp of Comparative Example 7. became.

  By comparing Example 2 and Example 14, the suspension stability of the finally obtained mercerized soft cell fibers can be adjusted even if the process order of the mercerization process and the fine fiber process is changed. It can be seen that equivalent performance can be obtained.

  From the above results, the separator paper for alkaline batteries of the present invention can achieve high air permeability, and when used in alkaline batteries, internal short circuit due to contact of bipolar active materials is prevented, and mercury The effect of preventing internal short circuit due to the conductive zinc oxide crystal accompanying no addition is also great. In addition, it is clear that the electric resistance is small and the capacity can be increased.

(Evaluation of alkaline batteries)
Conducted an alkaline battery discharge test (75 Ω for 150 hours) using a mercury-free zinc active material produced using the separator paper for alkaline batteries obtained in Examples and Comparative Examples (excluding Comparative Example 5), The discharge voltage of the battery before and after the test was measured. The results are shown in Table 1.

  As is clear from Table 1, the batteries using the separator papers of Examples 1 to 14 have a high discharge voltage compared to the separator papers for alkaline batteries of Comparative Examples 1 to 4 and 6 to 7. Was confirmed. Since the separator paper for alkaline batteries of the comparative example is not dense enough, the battery causes an internal short circuit due to the conductive zinc oxide crystals generated with the use of the mercury-free zinc active material. In the case of 1-14 separator paper for alkaline batteries, it can be considered that the conductive zinc oxide crystals were sufficiently blocked by the separator paper to prevent internal short circuit of the battery.

  The separator paper for alkaline batteries of the present invention can be used for alkaline batteries such as alkaline manganese batteries, silver oxide batteries, nickel zinc batteries, and zinc-air batteries.

Claims (4)

  A separator paper for an alkaline battery for separating a positive electrode and a negative electrode of an alkaline battery, characterized by containing mercerized parenchymal fibers obtained by mercerizing cellulose fibers obtained from plant parenchyma tissue. Alkaline battery separator paper.   The separator paper for alkaline batteries according to claim 1, wherein the content of mercerized parenchymal fibers is 1 to 30% by mass.   The separator paper for alkaline batteries according to claim 1 or 2, wherein the suspension stability of mercerized soft cell fibers is 50% or more.   Furthermore, alkali-resistant synthetic fiber is contained, The separator paper for alkaline batteries in any one of Claims 1-3 characterized by the above-mentioned.