JPH0381265B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a separator for a storage battery, and particularly to a separator for a storage battery with improved electrolyte retention. [Prior Art] A mat-like sheet of glass fiber with an average diameter of 1 μm or less has been proposed as a separator with excellent electrolyte retention for sealed lead-acid batteries.
In particular, it has been put to practical use in small-capacity sealed lead-acid batteries that use plates with a height of approximately 120 mm or less. However, in large batteries where the electrode plate height is, for example, 180 mm or more, the upper part of the mat-shaped sheet holds a much smaller amount of electrolyte than the lower part, so there is a drawback that the desired performance cannot be obtained. This is because the diameter of the fibers is relatively large, so the height of liquid absorption due to capillary action is reduced. A combination of fibers and powder is known as a separator intended to improve the electrolyte retention property by increasing the liquid absorption of the separator. For example, Japanese Patent Application Laid-open No. 54-22531 states that ``paper is made by mixing fibrillated thermoplastic synthetic fibers with a mouth water content of 200 to 600 c.c., thermoplastic synthetic fibers, and acid-resistant inorganic fibers or powder. , and the intertwined synthetic fibers are thermally fused to each other to form a single press-formed plate.'' is disclosed in JP-A-56-560110. Japanese Utility Model Application Publication No. 49-122327 discloses a separator consisting of one or two of linter pulp, synthetic fibers, and glass fibers, and silicic acid powder, or a separator containing silicic acid powder as the main component and acid-resistant inorganic fine powder added thereto. A separator made of mixed paper and bonded with a synthetic resin is disclosed. Further, JP-A-58-206046 discloses a separator made of glass fiber or synthetic fiber holding SiO ₂ particles. However, unless a special binder is used in the above-mentioned separator, the powder particles are likely to peel off or fall off when the separator is handled, which may cause problems in battery assembly work and the like. Furthermore, the use of a binder increases the cost of raw materials, and in a storage battery incorporating the separator, the binder gradually dissolves during use, contaminating the electrolyte and potentially deteriorating the performance of the battery. [Object of the Invention] The object of the present invention is to solve the problems of the above-mentioned prior art, and to solve the problem of the above-mentioned conventional technology. The object of the present invention is to provide a separator for a storage battery that is [Structure of the Invention] In order to achieve this object, the separator for a storage battery of the present invention is produced by wet-mixing fibers mainly composed of alkali-containing silicate glass fibers and powder mainly composed of alkali-containing silicate glass powder. , in which the pore size is made finer by interposing powder particles in the gaps between the glass fibers, and the fibers or the fibers and the powder particles are bonded to each other mainly by a water glass-like substance produced during papermaking. Fibers mainly composed of alkali-containing silicate glass fibers with an average diameter of 0.5 to 1.0 μm and powders mainly composed of alkali-containing silicate glass powders having an average diameter of 20 μm or less are wet-mixed and heat-treated. , a separator for a storage battery in which the fibers are entangled and the powder particles are interposed between the fibers, the amount of the powder being 1 to 40% of the weight of the separator;
A separator for a storage battery characterized by a weight%. That is, according to the present invention, powder particles are inserted into the spaces between the glass fibers, thereby forming a separator with fine pores and improving the liquid holding power. In addition, such fibers and particles are mainly bonded to each other by a water-glass adhesive layer formed on the surface of the alkali-containing silicate glass fibers and powder, and the powder does not peel or fall off even without the use of a special binder, making it easy to handle. becomes easier. The present invention will be explained in more detail below. First, fibers will be explained. The fibers constituting the separator of the present invention are mainly composed of alkali-containing silicate glass fibers. That is, it may contain only alkali-containing silicate glass fibers, or it may contain other fibers, such as thermoplastic organic fibers that are often mixed in glass fiber separators. The average diameter of the alkali-containing silicate glass fibers, which are the main fibers, is 0.5 to 1.0 μm, more preferably 0.6 to 1.0 μm.
It is 0.9 μm. If the diameter exceeds 1.0 μm, the porosity of the separator becomes small, and conversely, if the diameter becomes smaller than 0.5 μm, the manufacturing cost increases. Moreover, the average length of this glass fiber is preferably 7
~50mm, more preferably 10-40mm. If the average length is shorter than 10 mm, the strength of the separator will be reduced, and if it is longer than 50 mm, it will be difficult to uniformly disperse it in water during papermaking. In addition to glass fibers with a diameter of 1 μm or less,
Alkali-containing silicate glass fibers of 1 μm or more, for example, 5 to 30 μm, can be contained in an amount up to 20% by weight of the separator weight. This glass fiber of 1μm or more is 5
Preferably, the length is from mm to 80 mm. Adding this large diameter glass fiber increases the tensile strength of the separator. Such alkali-containing silicate glass fibers having an average diameter of 0.5 to 1.0 μm can be produced by the FA method (flame method), centrifugation method, or other short glass fiber manufacturing methods. The average diameter of the glass fibers is calculated by taking photographs of three locations on the sample using an electron microscope, measuring the diameters of each of the 20 fibers to the nearest 0.1 μm, and taking the average value of these measurements. Note that a suitable range of the glass composition will be described later. The separator of the present invention may contain thermoplastic organic fibers in addition to such alkali-containing silicate glass fibers, but in that case, the mixing ratio is preferably 7% by weight or less of the weight of the separator.
This is because if the amount of organic fibers mixed exceeds 7% by weight, depending on the material of the organic fibers, it may have an adverse effect on battery performance. Note that when thermoplastic organic fibers are used, the tensile strength of the separator is improved. This thermoplastic organic fiber preferably has a length of 2 to 10 mm and an average diameter of 1 to 300 μm. Examples of thermoplastic organic fibers include acrylic fibers and polyester fibers. Next, the powder will be explained. The powder used in the separator of the present invention is mainly composed of alkali-containing silicate powder, and it is also possible to use only alkali-containing silicate powder, or in a range of 50 parts by weight or less out of 100 parts by weight of powder. Silica powder (preferably silica powder having a specific surface area of 100 m ² /g or more) can be mixed and used. When a portion of the glass powder is replaced with silica powder in this way, the liquid absorption properties of the separator are improved. The average diameter of the glass powder used is 20 μm or less, preferably 6 μm or less. When the average diameter exceeds 20 μm, the spacing between the glass fibers becomes wider and the liquid absorbency decreases.
The bonding strength between the particles and the fibers decreases, making it easier for the particles to fall off from the separator. In the present invention, the average diameter of the glass powder is determined by photographing three locations of the sample using an electron microscope, measuring the diameter of each of 100 particles in units of 0.1 μm, and calculating the average value. In the separator of the present invention, the amount of powder mainly composed of alkali-containing silicate glass powder is 1 to 40% by weight of the separator weight. Particularly preferred is 5 to 30% by weight. If the amount of powder is less than 1% of the weight of the separator, the effect of improving liquid absorption is poor, and if it exceeds 40%, the tensile strength of the separator will be insufficient. Also,
The density of the separator increases, resulting in a lower void ratio. When the porosity is small, it becomes difficult for the gas generated at the electrode to move. Next, the compositions of glass fiber and glass powder will be explained. The glass fibers and glass powder constituting the separator of the present invention have an alkali-containing silicate glass composition, and can form water glass on the surface thereof. Moreover, since it is used for storage batteries, those with good acid resistance are preferably used. The degree of acid resistance is preferably such that the weight loss is 2% or less when measured according to JISC-2202 in the state of glass fibers with an average fiber diameter of 1 μm or less. In addition, the composition of such glass fiber and powder is 60 to 60% by weight.
75% _SiO2 , and 8-20% _R2O ( _Na2O , _K2O
mainly contains alkali metal oxides such as
(However, SiO ₂ + R ₂ O is 75 to 90%), and also contains one or more of CaO, MgO, B ₂ O ₃ , Al ₂ O ₃ , ZnOFe ₂ O ₃ , etc. It will be done. An example of a preferable alkali-containing silicate glass is shown in Table 1 below.

[Table] The separator for storage batteries of the present invention is made by combining fibers mainly composed of alkali-containing silicate glass fibers and powders mainly composed of alkali-containing silicate glass powders, for example, PH
The fibers are dispersed in water whose value is maintained between 2.5 and 3.5 for a certain period of time, for example, 5 to 20 minutes, using a water jet dispersion machine, etc., without cutting as much as possible, and then wet-processed to form the glass fibers. and forming an adhesive layer, perhaps a water glass layer, on the surface of the glass powder, and then heating this to a predetermined temperature, for example 80 to 180°C, thereby bonding the glass fibers and the glass powder to each other by the water glass on the surface. It can be obtained by That is, since the glass fibers and glass powder constituting the separator of the present invention have an alkali-containing silicate glass composition, the alkali components and silica components in the glass react with water for dispersion, and a water glass layer forms on the surface of the glass fibers. This water glass layer acts as an adhesive to bond the glass fibers and glass powder together. In addition, when thermoplastic organic fibers are used as part of the fibers, these organic fibers also exhibit a shaping or adhesion effect in the subsequent heat treatment step (for example, drying step), increasing the strength of the separator. The thickness of the separator itself of the present invention varies depending on the storage battery used, but is preferably 0.3 to 3 mm. Note that a dispersant may be used when dispersing the glass fibers in water. In addition, by spraying dialkyl sulfosuccinate onto a wet-processed fiber paper product, for example, a fiber paper product on a paper-making conveyor, the dialkyl sulfosuccinate can be applied to the glass fibers in an amount of 0.005 to 10% by weight. The hydrophilicity of fusuccinate can improve the liquid retention of the separator. Instead of spraying the dialkyl sulfosuccinate as described above, it may be mixed into the dispersion water in the papermaking tank. [Embodiments of the Invention] Examples will be described below. Example Using glass fiber whose composition is A in Table 1,
Average diameter 0.8μm, average length 10mm, by flame method.
Glass fibers with an average diameter of 19 μm and an average length of 25 mm were produced. In addition, a glass powder with an average diameter of 5 μm obtained by crushing glass cullet having a similar composition was prepared. In addition, a commercially available acrylic organic fiber (trade name: Cashmilon) was cut into a length of 7 mm and prepared. Furthermore, a commercially available silica powder having a specific surface area of 230 m ² /g (trade name: Carplex #80, manufactured by Shionogi & Co., Ltd.) was prepared. These fibers and powder were poured into water in the proportions shown in Table 2, stirred and dispersed using a water jet disperser, and sulfuric acid was added to bring the pH of the water to 2.7, which was maintained for about 10 minutes. Next, papermaking was performed and heated to 150°C to produce a pine-shaped storage battery separator. It was observed that each glass fiber and glass powder constituting this separator were bonded to each other by water glass formed on the surface thereof. These separators had the thickness, basis weight, density, tensile strength, and 24-hour liquid absorption height as shown in Table 2. The method for measuring these characteristic values is as follows. (1) Thickness Measure with the sample pressed in the thickness direction with a load of 20 kg/dm ² . (JISC-2202) (2) Density When the thickness of the sample is T when a load (W) of 20 kg is applied to the area (S) of the sample 10 cm x 10 cm, the formula: W/(S x T) (g /cm ³ ). (3) Fabric weight This is the value obtained by dividing the sample weight by the sample area. (4) Tensile strength Displayed as the external force (Kg) when pulling both ends of a 15 mm wide sample and causing it to break. (5) 24-hour liquid absorption height The sample is held vertically and its lower part is immersed in a dilute sulfuric acid solution with a specific gravity of 1.30, and the height is expressed as the distance that the dilute sulfuric acid rises in 24 hours. Comparative Examples 1 and 2 A separator was manufactured in the same manner as in the example except that only glass fiber was used in the proportions shown in Table 2 without using powder, and its properties were measured. The results are also shown in Table 2.

[Table] From Table 2, it can be seen that the separator of the present invention has significantly superior 24-hour liquid absorption height and high strength compared to those of Comparative Examples 1 and 2 that did not use powder. When similar tests were conducted on glass fibers having compositions B and C in Table 1, similar results were observed. As is clear from the comparison between Example 1 and Comparative Example 2 and the comparison between Example 2 and Comparative Example 1, if glass powder is not added, the 24-hour liquid absorption height is significantly lower.
Liquid absorption becomes poor. Moreover, the tensile strength also becomes low. Furthermore, as is clear from the comparison between Example 3 and Example 5, the addition of thermoplastic organic fiber significantly increases the tensile strength. Comparison between Example 1 and Example 2, and Example 3
As is clear from the comparison between Example 4 and Example 4, adding large diameter glass fibers increases the tensile strength of the separator. Comparison between Example 1 and Example 3, and Example 2
As is clear from the comparison with Example 4, when a part of the glass powder is replaced with silica powder, the liquid absorption property (24-hour liquid absorption height) is improved. Comparative Example 3 A separator was produced in the same manner as in Example 2 except that the average diameter of the glass fibers was 0.4 μm. Comparative Example 4 A separator was produced in the same manner as in Example 2 except that the average diameter of the glass fibers was 1.1 μm. Comparative Example 5 A separator was produced in the same manner as in Example 2, except that the average diameter of the glass powder was 30 μm.

[Table] Comparative Example 6 A separator was produced in the same manner as in Example 2 except that the amount of glass fiber was 50% by weight and the amount of glass powder was 50% by weight. The results of Comparative Examples 3 to 6 are shown in Table 3. Note that Table 3 also shows Example 2 and Comparative Example 1 in Table 2 above. The following can be seen from Table 3. If the diameter of the fine glass fiber is smaller than 0.5 μm, the cost will be high. (Comparative Example 3). As shown in Comparative Example 4, the diameter of the small glass fiber is
When it is larger than 1.0 μm, the density becomes considerably high. In addition, liquid absorbency decreases. Furthermore, the tensile strength also decreases. When the glass powder diameter is larger than 20μm,
The liquid absorption height for 24 hours becomes smaller (Comparative Example 5). Moreover, the tensile strength also decreases. If the amount of glass powder exceeds 40% by weight, the density of the separator becomes high, which is not preferable. Also,
Tensile strength decreases (Comparative Example 6). [Effects of the Invention] As described in detail above, the separator for a storage battery of the present invention has excellent liquid retention ability, and in particular, has a large liquid absorption height, so that a large amount of electrolyte can be retained even in the upper part of the separator. Incidentally, since glass powder and silica powder are considerably cheaper than glass fiber, the material cost of the separator of the present invention is also low. In addition, the particles and fibers are mainly bonded with a water glass-like substance, so that the particles do not peel or fall off, so there is no inconvenience in handling. Furthermore, there is no risk of electrolyte contamination due to binder elution from the separator, and deterioration of battery performance due to binder elution is prevented.

Claims (1)

[Claims] 1 Fibers mainly composed of alkali-containing silicate glass fibers with an average diameter of 0.5 to 1.0 μm and powders mainly composed of alkali-containing silicate glass powders having an average diameter of 20 μm or less are wet-mixed and heat-treated to form the fibers. A separator for a storage battery, wherein the powder particles are interposed between the fibers and the powder particles are interposed between the fibers, the amount of the powder being 1 to 10% of the weight of the separator.
A separator for storage batteries characterized by 40% by weight.