JPH08195194A - Separator for sealed lead-acid battery - Google Patents

Abstract

PURPOSE: To provide a separator for a sealed lead-acid battery having large tensile strength, rigidity, and liquid absorbing property, having little reduction of repulsion after an electrolyte is injected, and having the improved assembling work of an electrode plate group and battery characteristics. CONSTITUTION: Fibril-like synthetic fibers 0.5-10wt.%, mono-filament-like acid- resistant glass fibers 10-20wt.% having the average fiber diameter 9-20μm and the fiber length 5-25mm, and acid-resistant glass fibers (acid-resistant glass wool) 70-94wt.% expressed by the equation R=4/Sg×Ss and having the average fiber diameter 1μm or below are combined to obtain a separator having the specific surface area 1m<2> /g or above. In the equation, R is the average fiber diameter of glass fibers, Sg is the specific gravity of glass, and Ss is the specific surface area of glass fibers obtained by the BET method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution impregnated separator for a sealed lead acid battery.

[0002]

2. Description of the Related Art The applicant previously filed Japanese Patent Publication No. 62-3370.
No. 0 gazette discloses that fibers are mainly composed of glass fibers (acid-resistant glass wool), to which about 10 wt.% Of fibrillar synthetic fibers having a freeness of 350 cc or less are added. %, A papermaking type separator for a sealed lead acid battery, which has a significantly increased tensile strength and has a good liquid retention property, has been disclosed.

[0003]

However, the above-mentioned conventional separator is assembled into a positive electrode plate and a negative electrode plate as a group of electrode plates, housed in a battery case, fixed with a predetermined pressure, and sealed lead. When the storage battery was assembled and used, the repulsive force was remarkably reduced when the electrolyte was injected, and the adhesion with the electrode plate was reduced, which was a cause of deterioration of the battery performance. In view of the above conventional inconvenience, it is desired to develop a separator that suppresses the reduction of the repulsive force as much as possible even after the injection of the electrolytic solution, maintains good adhesion to the electrode plate, and improves the battery performance. .

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a bag-shaped separator for a sealed lead acid battery, which solves the above-mentioned conventional inconveniences and satisfies the above-mentioned demands, and has an average fiber diameter of about the following formula. 75 to 94 wt.% Of wool-like acid resistant glass fiber (acid resistant glass wool) having a thickness of 1 μm or less. %, Freeness 35
0.5-10w of fibrillar synthetic fiber of 0 cc or less
t. % And average fiber diameter 9 to 20 μm, fiber length 5 to 25 m
5-20w of monofilament-shaped acid resistant glass fiber
t. %, A separator for a sealed lead-acid battery, which is formed by mixing papermaking and forming into paper having a specific surface area of 1 m ² / g or more. Note R = 4 / Sg × Ss where R is the average fiber diameter of the glass fiber Sg is the specific gravity of the glass Ss is the specific surface area of the glass fiber determined by the BET method

[0005]

The acid-resistant glass fiber having an average fiber diameter of about 1 μm or less is added in an amount of 70 to 94 wt. % Of fibril-like synthetic fiber
10 wt. %, The tensile strength and rigidity are improved, which facilitates the battery assembling work and provides good liquid retention. On the other hand, when the specific surface area of the separator is 1 m ² / g or more, it is good. In addition to this, the monofilament-shaped acid-resistant glass fiber having an average fiber diameter of 9 to 20 μm and a fiber length of 5 to 25 mm is added to 5 to 20 wt. %, The decrease in the repulsive force of the separator after the injection of the electrolytic solution is suppressed, good adhesion with the electrode plate is maintained, and the battery performance is improved.

In this case, when the freeness of the fibrillar synthetic fiber is 350 cc or less, it is preferable because a separator having a good liquid absorbing property and a liquid retaining property can be secured. Further, when acrylic fiber is used as the material of the fibrillar synthetic fiber, it has excellent rigidity, elasticity, acid resistance, etc., so that it has excellent characteristics such as bending fatigue resistance of polyethylene, polypropylene or the like alone. It is preferable to use a fibrillar synthetic fiber mixed with the olefin fiber.

[0007]

Next, embodiments of the present invention will be described. The electrolytic solution-impregnated sealed lead-acid battery separator of the present invention comprises three types of fibers. That is, it was determined by the formula 4 / (Sg × Ss) (where Ss represents the specific surface area of the glass fiber determined by the BET method, and Sg represents the specific gravity of the glass). Average fiber diameter about 1 μm
Mainly consists of the following acid-resistant glass fibers (acid-resistant glass wool), to which 1 μm or less of fibril-like synthetic fiber is added.
0 wt. % Or less is no different from the above-described separator disclosed above, and further, a monofilament-shaped acid resistant glass fiber is added thereto in an amount of 5 to 20 wt. % Mixing. Acid-resistant glass wool having an average fiber diameter of about 1 μm or less is 70 to 94 wt. By blending in the range of%, as shown in FIG. 1, the specific surface area of the entire separator becomes 1 m ² / g or more. As a result, good liquid absorption and liquid retention properties can be maintained. When the average fiber diameter exceeds about 1 μm, specifically, exceeds 1.2 μm, the above-mentioned specific surface area is less than 1 m ² / g, which is unsuitable. Generally, glass wool having an average fiber diameter of 0.3 to 1 μm is used, and if the average fiber diameter is less than 0.3 μm, it becomes difficult to manufacture. As the glass wool, if the average fiber diameter is 1 μm or less, two or more kinds of glass wool can be mixed and used. The freeness of the fibrillar synthetic fiber is preferably 350 cc or less, 400 c
If it is c or more, it is difficult to obtain sufficient tensile force and rigidity within the above range of addition amount. The material of the fibrillar synthetic fiber is preferably polyacrylonitrile fiber alone or acrylic fiber made of a copolymer with a monomer such as vinyl chloride. Since the acrylic fiber has excellent acid resistance and toughness, it is particularly suitable for achieving the above object. The fibrillar acrylic fiber has 0.5 to 5 wt.% To maintain tensile strength and rigidity. % Formulation is required,
If desired, a small amount of olefinic fiber may be used together with the olefinic fiber to enhance the bending workability due to the excellent bending fatigue and adhesion of the olefinic fiber when it is bent into a U shape. .

According to the present invention, the above-mentioned specific acid resistant glass wool is mainly used, and the fibrillar synthetic fiber having the above-mentioned compounding amount is added thereto, particularly, the average fiber diameter is 9 to 20 μm, and the fiber length is 5 to 5.
5mm of 25mm monofilament acid resistant glass fiber
20 wt. % By blending and mixing, there is little decrease in repulsive force caused by the injection of the electrolyte, and liquid absorption,
The separator for a sealed lead-acid battery of the present invention having a good liquid retaining property can be obtained. Alkali-containing silicate glass (C glass) is generally used as the material for the acid-resistant glass wool and the monofilament heat-resistant glass fiber. Further, the reason why the average fiber diameter of the monofilament-shaped acid resistant glass fiber is set in the range of 9 to 20 μm is not preferable when the average fiber diameter is less than 9 μm because the effect of suppressing the decrease in repulsive force of the separator after liquid injection is reduced. On the other hand, when it exceeds 20 μm, the homogeneity in the sheet is deteriorated and, when the separator is bent in a U shape, the workability thereof is deteriorated, which is not preferable. Further, the fiber length of the monofilament-shaped acid-resistant glass fiber is 25 mm or less from the viewpoint of a homogeneous formation structure at the time of papermaking, although the effect of suppressing the repulsive force of the separator is increased by intersecting the monofilament-shaped fibers with each other. Is preferred, 25m
When it exceeds m, the homogeneity remarkably decreases, which is not preferable. On the other hand, when the fiber length is less than 5 mm, the frequency with which the fibers cross each other decreases, the ratio of the fibers independently existing in the papermaking sheet increases, and the separator does not bring about the effect of suppressing the reduction in repulsive force, which is not preferable. In short, the compounding amount of the monofilament acid-resistant glass fiber having the average fiber diameter and the fiber length in the above-mentioned specific ranges is 5 to 20 wt. % Range is preferable, and 5 wt. When it is less than%, the effect of suppressing the repulsive force reduction of the injected separator is not substantially produced. Also, 20w
t. When it exceeds%, the homogeneity of the separator sheet at the time of papermaking decreases, and it becomes difficult to manufacture a homogeneous separator.

Next, more specific examples of the present invention will be described together with comparative examples and conventional examples. The three types of fibers shown in Table 1 below were put into water having a pH of 3 with sulfuric acid at the respective blending ratios shown in Table 1, stirred for 20 minutes with a mixing and dispersing machine, and then papermaking was performed to obtain the thickness. 1.0 mm of each separator was obtained.

[0010]

[Table 1]

For each of the above separators, the repulsive force retention rate after injection, tensile strength, rigidity, and
The liquid absorption rate was measured. Test method: (1) Retention rate after liquid injection: After drying, separator sample 100 × 100 mm 10 sheets, 3
Collect sets and place these in PE bags. A sample (10 sheets in a set) containing a PE bag was set in a horizontal compression tester equipped with a load cell and dried at 20 kg /
Pressurize to a pressure of 100 cm ² . Immediately pour the saturated amount of water into the PE bag containing the sample and adjust the pressure to 2
Read after 0 minutes. The repulsion retention rate (%) after pouring is calculated from the average value of pressure 20 minutes after pouring by the following formula. Repulsion retention rate after pouring (%) = (pressure average 20 minutes after pouring)
÷ (20 Kg / 100 cm ² ) × 100 (2) Tensile strength: According to JIS C 2313. (3) Rigidity: According to JIS P8125. (4) Liquid absorption rate: separator sample 100 x 100 m after drying
After stacking m10 sheets in a PE bag and setting in a horizontal compression tester equipped with a load cell, a saturated amount of water was poured into the PE bag to remove excess water, and then the volume of water absorbed by the sample was obtained. Obtain the liquid absorption rate by the following formula. Liquid absorption rate (%) = (volume of water absorbed by sample) / (20K
g / 100 cm ² Sample volume at pressurization) × 100 The above measurement results are shown in Table 2 below.

[0012]

[Table 2]

As is clear from Tables 1 and 2, the separators of the present invention all have a repulsive force retention ratio after injection which is higher than that of the conventional example in a state where tensile strength, rigidity and liquid absorption rate are maintained in good condition. However, it is recognized that it is significantly improved. It can be seen that this is all brought about by the addition of a certain amount of monofilament acid resistant glass fibers. Further, in Comparative Example 1, since no fibrillar acrylic fiber was added, it was found that the tensile strength and the rigidity were remarkably lowered, which was inconvenient for the assembly work of the electrode plate group. On the other hand, as is clear from the comparative example, the fibrillar acrylic fiber is 5 wt. It can be seen that if it exceeds%, the liquid absorption rate is lower than that of the conventional separator.

The fibrillar synthetic fiber is at least 0.5 wt. %, The tensile strength and rigidity required for the separator are imparted, and the compounding amount of the monofilament-shaped acid resistant glass fiber is 5 to 20 wt. % Range,
The amount of acid-resistant glass wool having an average fiber diameter of 1 μm or less is 75 to 94 wt. %, All the above properties are not satisfied, and if the average fiber diameter of the glass wool is not less than 1 μm, that is, the specific surface area of the separator is not more than 1 m ² / g, the liquid retention rate is remarkable. It is recognized that the battery performance is lowered, particularly, the battery performance is improved as compared with the conventional case by using the above-mentioned specific monofilament-shaped acid resistant glass fiber.

[0015]

As described above, according to the present invention, 0.5 to 5 w of fibrillar synthetic fiber having a freeness of 350 cc or less is used.
t. %, Average fiber diameter 9 to 20 μm, fiber length 5 to 25 mm
5-20w of monofilament acid resistant glass fiber
t. % And 75 to 94 wt.% Of acid resistant glass wool having an average fiber diameter of 1 μm or less. % To form a separator having a specific surface area of 1 m ² / g or more, the separator has extremely high tensile strength and rigidity required for battery assembly as compared with a conventional sealed lead-acid battery separator. Moreover, it has an effect of improving the adhesiveness to the electrode plate because it becomes a separator in which the repulsive force after the injection of the electrolyte with sufficient liquid absorption is suppressed, and therefore, it was applied to the sealed lead acid battery. In this case, the effects of improving the battery assembling property and extending the battery life are exhibited.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the average fiber diameter and the specific surface area of glass wool.

Claims (2)

[Claims] 1. A wool-like acid-resistant glass fiber having an average fiber diameter of about 1 μm or less (acid-resistant glass wool) obtained by the following formula 1.
75-94 wt. %, A fibrillar synthetic fiber having a freeness of 350 cc or less is 0.5 to 10 wt. %, An average fiber diameter of 9 to 20 μm, and a fiber length of 5 to 25 mm of monofilament-shaped acid-resistant glass fiber of 5 to 20 wt. %, Mixed papermaking,
A sealed lead-acid battery separator formed by molding a paper having a specific surface area of 1 m ² / g or more. ## EQU1 ## R = 4 / Sg × Ss where R is the average fiber diameter of the glass fibers Sg is the specific gravity of the glass Ss is the specific surface area of the glass fibers determined by the BET method 2. The sealed lead-acid battery separator according to claim 1, wherein the fibrillar synthetic fibers are composed of acrylic fibers alone or a mixture of acrylic fibers and olefin fibers.