JP2003242953A - Separator for sealed lead-acid battery, and sealed lead- acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for a sealed lead-acid battery made of glass fibers used as a main component, having low density and high tensile strength and elongation coefficient, capable of manufacturing a sealed lead-acid battery of high capacity with good yield. <P>SOLUTION: The separator for a sealed lead-acid battery is made of extremely thin glass fibers having an average aspect ratio of 3,000-15,000. The separator having excellent adhesion property to an electrode plate, due to the mutual tanglement of the extremely thin glass fibers, is provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed lead-acid battery separator mainly composed of glass fibers and a sealed lead-acid battery having the built-in separator, and particularly to low density, high tensile strength and high elongation. The present invention relates to a sealed lead-acid battery separator capable of producing a high-capacity sealed lead-acid battery with a good yield, and a sealed lead-acid battery incorporating the same.

[0002]

2. Description of the Related Art As a sealed lead-acid battery separator,
A sheet mainly composed of ultrafine glass fibers having excellent hydrophilicity is generally used. The separator of the sealed lead-acid battery has a function of preventing a short circuit between the positive electrode and the negative electrode of the battery and at the same time absorbing a sulfuric acid solution which is an electrolytic solution and holding the same. Since the electrolyte retained in the separator has a significantly reduced fluidity, oxygen gas generated in the positive electrode at the end of charging is moved to the negative electrode through the voids in the separator, causing a gas absorption reaction with the negative electrode active material, Thereby, the lead acid battery can be hermetically sealed.

However, if the electrolytic solution holding performance of the separator is not sufficient, the electrolytic solution in the battery gradually decreases with the lapse of time and a part of the electrolytic solution does not hold the electrolytic solution. As a result, a phenomenon called "stratification" that causes a difference in the density of the electrolytic solution is likely to occur. When such a phenomenon occurs, the active material of the electrode does not react sufficiently, the capacity of the battery decreases, and the battery life is significantly impaired.

For this reason, a separator using ultrafine glass fibers having a fiber diameter of 1 μm or less has been proposed for the purpose of holding the electrolytic solution and preventing the active material from falling off (JP-A-59).
-71255, JP-A-59-138058). The ultrafine glass fibers are generally relatively short glass fibers having an average aspect ratio (fiber length / fiber diameter) of 2000 or less. Further, in the past, in order to maintain the pressing force between the electrode plates after injecting the electrolytic solution, the density of the separator is 0.17 g.
/ Cm ³ (when compressed at 19.6 kPa) or more.

[0005]

The above conventional separator has the following problems. Since the density of the separator is high, the volume occupied by the separator in the battery is high, and the porosity is low, the amount of the electrolytic solution that reacts with the active material is small. Therefore, the battery capacity is low. Since the separator has a high density, the surface of the separator becomes hard, the irregularities on the surface of the electrode plate and the separator cannot be absorbed by each other, and a gap is easily formed between the electrode plate and the separator.
When the adhesion between the electrode plate and the separator is poor, the internal resistance of the battery increases and the capacity decreases. Since the fiber length of the glass fiber is short, there is little entanglement between the fibers and the density is high, but the strength is low,
Easy to cut when assembling batteries. In addition, since the separator has a high density and is hard, it is difficult to fit the mold to the electrode plate by bending, the tension applied to the outside of the separator during the bending process cannot be absorbed, and the separator is likely to crack.

The present invention solves the above-mentioned conventional problems and is a separator for a sealed lead-acid battery mainly composed of glass fiber, which has a low density, a high tensile strength and a high elongation, and a high capacity sealed lead. An object of the present invention is to provide a sealed lead-acid battery separator capable of manufacturing a storage battery with a high yield and a sealed lead-acid battery having the separator built therein.

[0007]

The sealed lead-acid battery separator of the present invention is a sealed lead-acid battery separator mainly composed of glass fibers, in which at least a part of the glass fibers constituting the separator is And ultrafine glass fibers having an average aspect ratio of 3000 to 15000.

By using ultrafine glass fibers having a long fiber length with an average aspect ratio (fiber length / fiber diameter) of 3000 to 15000, the entanglement of the fibers becomes strong, the density is low, the flexibility is high, and the tensile strength is high. It is possible to obtain a high separator.

In the present invention, it is preferable that the separator is substantially composed of only glass fibers, and 50% by weight or more of the glass fibers constituting the separator, especially all of them are ultrafine glass having an average aspect ratio of 3000 to 15000. It is preferably a fiber.

The ultrafine glass fibers used in the present invention preferably have an average fiber diameter of 1 μm or less.

In the present invention, the density of 0.13 to 0.16 is obtained by using the ultrafine glass fiber having the above aspect ratio.
It is preferable to use a low-density separator of about g / cm ³ .

In the present invention, the density means the separator in the thickness direction of 19.6 kPa (20 kg / dm).
² ) Density in the state of being pressed and compressed by the load.

According to such a separator of the present invention,
A high-strength and highly elastic separator having a tensile strength of 1.5 N / 10 mm ² or more and an elongation at break of 5% or more is provided. The method for measuring the tensile strength and the elongation at break is as described in Examples below.

The sealed lead acid battery of the present invention incorporates such a sealed lead acid battery separator of the present invention, and has a high capacity and excellent battery performance.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the sealed lead-acid battery separator and the sealed lead-acid battery of the present invention will be described below in detail.

First, the ultrafine glass fiber used in the present invention will be described.

The ultrafine glass fiber used in the present invention is an ultrafine glass fiber having an average aspect ratio of 3000 to 15,000, preferably an average aspect ratio of 8,000 to 15,000 and having a large aspect ratio and a long fiber length.

When the average aspect ratio of this ultrafine glass fiber is 3000 or less, sufficient entanglement of the glass fibers cannot be obtained, so that the density of the separator is lowered, the tensile strength,
The effect of improving the elongation rate and the flexibility cannot be sufficiently obtained. The larger the aspect ratio, the more the glass fibers are entangled with each other, but the average aspect ratio is 15,000.
If the glass fiber exceeds such a length, it becomes difficult to uniformly disperse the glass fiber at the time of paper making and the like, and the tensile strength tends to be rather lowered.

The average fiber diameter of this ultrafine glass fiber is usually 1 μm or less, preferably 0.6 to 1 μm.

The glass fibers having a large aspect ratio and a long fiber length as described above depend on the temperature-viscosity characteristics of the glass when producing ultrafine glass fibers by the flame spraying method (FA method) or the centrifugal force method (rotary method). It can be produced by adjusting the spinning temperature, the temperature of the cloth blown at the time of fiberizing, the pressure, etc. to obtain a predetermined fiber diameter and fiber length.

The method for producing the ultrafine glass fiber used in the present invention will be described below with reference to FIG.

(1) FA Method In the FA method, as shown in FIG.
Long glass fibers are continuously spun by a roller 3 from a bushing 2 provided at the bottom of the glass fiber, and the glass long fibers are melted and blown off by a flame of a burner 4 to produce short glass fibers. In producing glass fibers by this FA method, by selecting the melting temperature, the drawing temperature, the nozzle diameter of the bushing 2, the output of the burner 4, etc., according to the temperature-viscosity characteristics of the glass raw material, it is possible to obtain ultrafine particles with a predetermined aspect ratio. Glass fibers can be manufactured.

(2) Rotary Method The rotary method is a method in which molten glass is blown off from the wall of a container that rotates at high speed. That is, as shown in FIG. 1B, the molten glass flowing down from the melting furnace 6 is received by the rotating body (spinner 7), blown away from the spinner 7 in the radial direction, and air (or flame) is sprayed from the nozzle 8. And draw it into a fine long glass fiber. By selecting the melting temperature and drawing temperature of the glass, the number of rotations of the spinner, the hole diameter of the spinner, the gas ejection speed of the nozzle, and the like, it is possible to manufacture ultrafine glass fibers having a predetermined aspect ratio.

The sealed lead-acid battery separator of the present invention comprises:
It may be composed of only ultrafine glass fibers having an average aspect ratio of 3000 to 15000, and together with such ultrafine glass fibers having a high aspect ratio, an average aspect ratio of less than 3000, for example, an average aspect ratio of 500.
Ultrafine glass fibers having a low aspect ratio of up to 2000 may be used in combination. The combined use of such an ultrafine glass fiber having a high aspect ratio and an ultrafine glass fiber having a low aspect ratio is advantageous in terms of improvement of pressure and cost. However, in this case, it is preferable that the ultrafine glass fibers having an average aspect ratio of 3000 to 15000 account for 50% by weight or more, particularly 70% by weight or more of the glass fibers constituting the separator.

The sealed lead-acid battery separator of the present invention is preferably composed essentially of glass fibers only, but may be blended with inorganic powder such as silica or synthetic fibers. However, in order to effectively exhibit the liquid absorbing property of the hydrophilicity of the glass fiber and the high liquid retaining property, the sealed lead-acid battery separator of the present invention does not contain these other components, It is preferably composed of only glass fibers.

The sealed lead-acid battery separator of the present invention comprises:
It can be produced by a conventional papermaking method. In this papermaking, the pH of the papermaking water (circulation water) is usually acidified to 2 to 4, whereby the glass fiber surface reacts with the acid and the alkali content of the glass is replaced with the acid (hydrogen) to produce Si- Water glass of OH.H ₂ O is produced, and the produced water glass adheres the intersections of the entanglement of the glass fibers.

As a method for making a glass fiber separator, a method is also used in which the pH of papermaking water (circulating water) is made neutral, water glass such as this is not formed, and only glass fibers are entangled to form a sheet. According to this method, a more flexible separator can be manufactured. However, in a separator having no adhesive force due to water glass, the strength is reduced, and the strength required for the separator may not be obtained. Not applied, pH 2-4
It is preferable to carry out papermaking under the conditions of

The thickness of the separator of the present invention itself varies depending on the storage battery used, but is generally 0.3 to 3 m.
It is preferably m.

According to the present invention, by using the ultrafine glass fiber having a large aspect ratio, the density (19.6 kP
a) 0.13 to 0.16 g / cm ³ , especially 0.1.
13~0.15g / cm ³ and the low, the tensile strength is 1.5N
/ 10 mm ² or higher, especially 2.0 N / 10 mm ² or higher,
Moreover, it is possible to provide a highly flexible separator having an elongation at break of 5% or more, particularly 6% or more.

The separator of the present invention is housed in the container of the sealed lead acid battery so as to separate the electrodes, and thus the sealed lead acid battery is constructed.

[0031]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

In the following examples and comparative examples,
The glass fibers A and B used for manufacturing the separator are as follows. Glass fiber A: Glass fiber having an average fiber diameter of 0.8 μm and an average aspect ratio of 5000 (composition component content is shown in Table 1) Glass fiber B: Glass fiber having an average fiber diameter of 0.8 μm and an average aspect ratio of 2000 (composition component (The content is shown in Table 1)

[0033]

[Table 1]

The methods for measuring the physical properties and characteristics in the examples and comparative examples are as follows. Unit weight (g / m ² ): Calculated by dividing the sample mass by the sample area. Density (g / cm ³ ): 19.
It was measured in a state of being pressed with a load of 6 kPa (20 kg / dm ² ) (JISC-
2202) It was calculated from the thickness T (mm) and the basis weight W (g / m ² ) by the following formula. W / 1000T Liquid absorbency (mm / 5 min): The sample was made vertical, and the lower part thereof was immersed in dilute sulfuric acid having a specific gravity of 1.30, and the liquid level rising in 5 minutes was measured. A large liquid absorbing property indicates that the electrolytic solution permeates quickly and that the electrolytic solution has a good liquid retaining property. Tensile strength (N / 10 mm ² ): Measured by SBA4501. High tensile strength indicates that the separator is difficult to cut during battery assembly. Elongation at break (%): "LO manufactured by SHIMADZU
AD CELL AGS-5KND "
It was measured by 4501. High elongation at break means
It shows that the bending process at the time of assembling the battery makes it easy to fit the electrode plate and does not easily generate cracks. Thickness retention rate (%) when weighted: The thickness was measured while the sample was pressed in the thickness direction with a load of 9.8 to 98 kPa (10 to 100 kg / dm ² ), and when the sample was loaded with 9.8 kPa or 19 The relative value was calculated with 100% under the load of 0.6 kPa. It is shown that the larger the thickness retention ratio under load is, the more flexible it is and the better the adhesion to the electrode plate when the battery is assembled.

Examples 1 and 2 and Comparative Example 1 The glass fibers shown in Table 2 were used, and the basis weight shown in Table 2 was used according to a conventional method by the papermaking method (pH of papermaking water (circulating water) was 2 to 4). A density separator was produced.

COMPARATIVE EXAMPLE 2 In Comparative Example 1, except that the softening process was carried out by setting the pH of the papermaking water (circulating water) to neutral (pH = 7) at the time of papermaking, the weight and the density shown in Table 2 were obtained in the same manner. A separator was manufactured.

Comparative Example 3 In Comparative Example 1, the glass fibers were dispersed at the time of paper making, and then the glass fibers were crushed using a crusher to shorten the fiber length,
Further, after papermaking, a separator having a basis weight and a density shown in Table 2 was produced in the same manner except that the thickness was crushed by a roller press to densify the sheet before it was completely dried.

The physical properties and characteristics of the separators obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were measured, and the results are shown in Tables 2 to 4 and FIG.

Table 3 shows the thickness retention rate under load of 19.
The relative value obtained by setting 6 kPa weighting as 100% is shown.
Table 4 shows the thickness retention rate under load is 9.8 kPa and the thickness retention rate is 10
The relative value obtained as 0% is shown. Further, FIG. 2 is a graph of Table 4.

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

From Tables 2 to 4 and FIG. 2, the separator of the present invention, which uses ultrafine glass fibers having a large aspect ratio, has a low density and an excellent liquid absorbing property, a high tensile strength, a high elongation rate, a flexibility and an elasticity. It can be seen that the separator is rich in properties.

On the other hand, an average aspect ratio of 2000
In Comparative Example 1 in which the conventional ultrafine glass fiber of Comparative Example 1 and the density of Examples 1 and 2 are set to the same level, the tensile strength is slightly deteriorated,
In particular, the elongation rate is small. Further, since the flexibility is insufficient, the thickness retention rate under load is large.

In Comparative Example 2 in which the conventional ultrafine glass fiber is used for softening, the elongation and flexibility are increased,
The tensile strength is extremely poor.

Further, in Comparative Example 3 in which the conventional ultrafine glass fiber was used to densify it by pressing, the tensile strength can be increased, but it is hard and inferior in flexibility.

[0047]

As described in detail above, according to the sealed lead-acid battery separator of the present invention, the following effects are exhibited. Since ultrafine glass fibers having a high aspect ratio are used, the fibers are often entangled with each other, and the density of the separator is reduced. Since the separator has a low density, it becomes flexible and sufficiently adheres to the surface of the electrode plate when it is pressed and inserted between the electrode plates. Therefore, a sealed lead-acid battery with low internal resistance can be manufactured. Since the fibers are often entangled with each other, the tensile strength is high,
Further, since the elongation rate is high, the separator is not cut during the assembling of the battery, and the separator is not cracked due to the bending process. Therefore, the sealed lead-acid battery can be manufactured with good yield and good workability. Since the density is low, the pore size is large and the electrolyte permeates quickly. Therefore, it is possible to prevent the compression force from decreasing. Since the density is low and the porosity in the battery is high, the amount of the electrolytic solution that reacts with the active material is increased, and the battery capacity can be increased. It is flexible, has high compression and decompression properties, and has little settling. The sealed lead acid battery of the present invention incorporates such a sealed lead acid battery separator of the present invention, and has a high capacity and excellent battery performance.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a method for producing an ultrafine glass fiber used in the present invention.

FIG. 2 is a graph showing the thickness retention rate of the separators manufactured in Examples 1 and 2 and Comparative Examples 1 to 3 when weighted.

[Explanation of symbols]

1 glass melting tank 2 bushings 3 roller 4 burners 6 melting furnace 7 Spinner 8 nozzles

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4L055 AF04 EA07 EA08 EA16 EA32                       FA30 GA01 GA50                 5H021 AA06 CC02 EE28 HH00 HH01                       HH03 HH05 HH06                 5H028 AA05 CC08 EE04 HH00 HH01                       HH03 HH05 HH09

Claims (8)

[Claims] 1. A sealed lead-acid battery separator mainly composed of glass fibers, wherein at least some of the glass fibers constituting the separator are ultrafine glass fibers having an average aspect ratio of 3000 to 15000. Characteristic sealed lead-acid battery separator. 2. The sealed lead-acid battery separator according to claim 1, wherein the separator is substantially composed of glass fibers. 3. The sealed lead-acid battery separator according to claim 1, wherein 50% by weight or more of the glass fibers constituting the separator are ultrafine glass fibers having an average aspect ratio of 3000 to 15000. 4. The sealed lead-acid battery separator according to claim 1, which is composed of only ultrafine glass fibers having an average aspect ratio of 3000 to 15000. 5. The sealed lead-acid battery separator according to claim 1, wherein the ultrafine glass fibers have an average fiber diameter of 1 μm or less. 6. The density according to claim 1, wherein the density (when compressed at 19.6 kPa) is 0.13 to 0.1.
A sealed lead-acid battery separator, which is 6 g / cm ³ . 7. The sealed lead-acid battery according to claim 1, wherein the tensile strength is 1.5 N / 10 mm ² or more and the elongation at break is 5% or more. Separator. 8. A sealed lead acid battery containing the sealed lead acid battery separator according to any one of claims 1 to 7.