JPH06236752A - Separator for lead-acid battery and its manufacture - Google Patents

Abstract

PURPOSE:To improve flexibility or peeling strength, and also battery life by forming integrally connected microporous coat layers of a mixture of a synthetic resin and an inorganic powder on both surfaces of a porous thin base material sheet through its innumerable pores. CONSTITUTION:Five to three wt.% of a synthetic resin such as acryl resin having a glass transition point of 0-20 deg.C is mixed, in the form of dispersion or emulsion, into 15-80wt.% of water together with an inorganic powder such as 15-50wt.% of diatom earth to form a mixed paste. This is applied to both surfaces of a porous base material sheet 4 consisting of an non-woven fabric such as polypropylene to have a dry weighting of 50-150g/m<2>. These coat layers are pressurized from both surfaces to form a fixed thickness, heated and dried, and further heated, whereby coat layers 5a fixed to both surfaces are integrally bonded to each other through innumerable openings 4a of the sheet 4, and a separator 5 for lead-acid battery remarkably improved in peeling resistance can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead storage battery separator and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a separator for a lead storage battery, it has been required to have particularly excellent microporosity and improved oxidation resistance. As a manufacturing method for obtaining the microporosity of such a separator, there is a method in which a separator base paper is attached to both surfaces of a microporous surface made of a mixture of synthetic resin and inorganic powder. Such a separator and its manufacturing method are disclosed in, for example, JP-A-57-385.
No. 64 is known. This known separator does not use a pore opening agent and an organic solvent, thus increasing the manufacturing cost, avoiding the problem of contamination by the organic solvent, and improving the oxidation resistance can be achieved, but the maximum pore diameter is 10 μm or less. Using a mixture reinforced layer of porous synthetic resin and inorganic powder as a base material,
Since it is a polymerization-strengthened separator for lead-acid batteries that is made by sticking separator raw paper on both sides, when MMA with an extremely high glass transition point Tg is used as the synthetic resin material, the mixture is reinforced in the manufacturing process. Since the layer is hardened by heating and drying to become a reinforced layer with high rigidity, the mixture reinforced layer is cracked or chipped due to vibration or impact in the subsequent working steps such as cutting, stacking, battery assembly, etc. In addition, if a separator that is cracked or chipped is overlooked and the electrode plate group is assembled into a battery, a short circuit between the electrode plates will occur.
Further, since the rigidity is high, cracks and chips easily occur, and it is difficult to process the separator into a bag-shaped separator that is folded in two. Further, in a lead storage battery having a built-in electrode plate group using the separator, a gas generated during charging thereof penetrates into the inside through the separator base paper on both sides of the separator, and the mixture reinforcing layer and the base paper on both sides thereof. It easily accumulates during this period, and as a result, the electric resistance inside the battery increases, leading to problems such as early deterioration of charge / discharge characteristics. On the other hand, a porous separator made of polyethylene has been used as a separator for a lead storage battery, but it is generally manufactured as follows. Polyethylene resin, inorganic powder, mineral oil, etc. are mixed and molded into a sheet using an ordinary extruder, then the mineral oil contained in the sheet is extracted using an organic solvent to form micropores in the sheet. It is manufactured by the method. In this case, a part of the mineral oil is left on the sheet to protect the polyethylene resin, which is the main material of the separator, from the oxidizing atmosphere generated in the lead storage battery reaction. However, the residual mineral oil is washed out from the separator to form a sticky substance each time the charge / discharge reaction at the time of initial charge or use of the lead storage battery is repeated, and the sticky substance is inside the lead storage battery cell. Not only does it make it difficult to check the electrolyte level when it adheres, but it also clogs the liquid stopper and its filter that are provided for the gas vents that sometimes occur in lead acid batteries, which makes it impossible to vent gas and lead acid batteries. There is a risk that the internal pressure of the cylinder may rise and the user may be at risk. Further, the polyethylene separator is
The traces occupied by the extracted mineral oil in the sheet become fine pores, and the pore size is only about 0.01 μm. The microporous sheet constituted only by such a small pore size has a poor diffusion of the electrolytic solution, and is particularly used as a bag-shaped separator. Electrolyte solution diffusion becomes poor, and the electrode plate wrapped in a bag is likely to supply the electrolyte solution at the rate-determining step of the lead-acid battery reaction during discharge, and it may not be possible to secure the electric capacity as initially designed. On the other hand, in the process of manufacturing this separator, a large amount of organic solvent is used to extract the mineral oil from the sheet after extrusion to form fine pores, so not only is the process dangerous, but it also causes environmental damage. There is a fear.

[0003]

The present invention provides a lead-acid battery separator that solves the above-mentioned conventional problems and a method for producing the same, wherein the lead-acid battery separator is provided on both sides of a porous thin substrate sheet. , A microporous coating layer made of a mixture of a synthetic resin and an inorganic powder, which are integrally connected to each other through innumerable openings of the base sheet, and which are integrally provided.
Further, the present invention provides a method for manufacturing the above-described lead acid battery separator, which comprises synthetic resin 5 to 35 wt.% And inorganic powder 15 to 50 w.
t.% and 15 to 80 wt.% of water as a medium to prepare a paste mixture, which is applied to both sides of the porous substrate sheet to form a coating layer by pressurizing and then dried by heating. Characterized by binding.

[0004]

Since the coating layer of the separator of the present invention contains a synthetic resin, flexibility is imparted to the coating layer. Therefore, cracking and chipping do not occur during subsequent handling. Further, since the coating layers formed on both sides of the porous base sheet are integrally connected to each other through the innumerable openings of the base sheet, peeling resistance to the surface of the base sheet is improved. Sex increases. Furthermore, even when used as a battery incorporated in the electrode plate group and gas is generated during charging, the gas does not accumulate between the coating layer and the surface of the base material sheet. Also,
There is no stain inside the battery. Furthermore, even when the separator of the present invention is in the form of a bag, when the electrode plate is housed and used,
(EN) Provided is a high performance lead storage battery capable of keeping good diffusion of an electrolytic solution. In this case, the dry basis weight of the coating layer is 50
When it is in the range of up to 150 g / m ² , it has excellent microporosity,
Since lead powder does not permeate, short circuit between the electrode plates can be prevented, and electric resistance can be kept low. In this case, the porous thin substrate sheet has a thickness of 0.05 to 0.20 mm and a density of
It is preferable to use one having a pore diameter of 0.15 to 0.40 g / cm ³ and a maximum pore diameter of 10 to 100 μm.

Further, according to the method for producing a lead-acid battery separator of the present invention, the synthetic resin is 5 to 35 wt.
By mixing 50 wt.% And 15 to 80 wt.% Water as a medium, a paste having good coatability is obtained, and when coating is applied to both sides of the base sheet to form a coating layer, The coating layers on both sides are in close contact with the base material and are integrally connected through the innumerable holes of the base material sheet. From this state, water is evaporated by heating, these coating layers are dried and become microporous, and the synthetic resin particles have flexibility by binding the base sheet surface and the inorganic powder particles to each other. A stable and acid-resistant and oxidation-resistant separator can be obtained. In addition, there is no danger of explosion or fire in the manufacturing process, and the manufacturing process can be performed safely. Further, since the coating layer of the separator is not peeled or cracked by bending, a bag-shaped separator can be obtained without manufacturing loss.

In this case, the synthetic resin is used in the form of dispersion or emulsion, and as the inorganic powder, the particle size is 0.1 to 5 μm and the specific surface area is 0.1 to 100 m ² / g.
When used, the paste preparation work and the coating work are easy, and the dry coating layer has excellent microporosity in which the passage of the active material having a pore size in the range of 0.1 to 10 μm is well prevented. A separator having the above and having acid resistance and oxidation resistance can be obtained.

In the production of a bag-shaped separator, the separator is folded in two and both side edges of the polymerized coating layer are bound by any means. However, since the coating layer contains a synthetic resin, Suitable for fusion bonding, especially by heat sealing, and easy and quick to obtain. Incidentally, as the lead-acid battery separator of the present invention, a plurality of ribs may be disposed on the coating layer surface, and according to this, when used as a leaf-shaped or bag-shaped separator, the electrode plate surface and A space is formed between the separator and the separator surface, gas is released and the electrolyte is diffused well, and in particular, oxidative deterioration due to contact with the anode plate can be prevented.

[0008]

EXAMPLES Next, examples of the present invention will be described in detail. The synthetic resin used for manufacturing the lead storage battery separator of the present invention,
Glass transition point Tg-10 to 30 ° C with excellent acid resistance and oxidation resistance,
Preferable acrylic resin at 0 to 20 ° C, polyolefin resin such as polyethylene, polypropylene and polybutadiene having excellent flexibility, polyvinyl chloride resin whose hardness can be adjusted with a plasticizer, polybutene having rubber-like elasticity, SBR It is a synthetic resin such as. The usage form is
Aqueous emulsions or dispersions are preferred for making the aqueous pastes described below. Then, such a synthetic resin and inorganic powder are mixed using water as a medium to form a paste, which is applied by pressure bonding to a porous thin base material sheet to form a coating layer, and then dried. The coating layer thus obtained retains its flexibility and can be obtained without cracks or defects against vibration, impact, etc.

As the inorganic powder, synthetic acid- and natural-silica-based, alumina-based, and silica-alumina-based powders which do not contain impurities, such as heavy metals, which are harmful to lead-acid batteries are preferably used as the inorganic powders. Typical examples thereof include diatomaceous earth, amorphous silica powder, and fused alumina powder. Above all, particle size 0.1-5.0 μm, specific surface area 0.1-100 m
The range of ² / g is preferable. Specific surface area is 0.1m ² /
If it is smaller than g or the average particle size is larger than 5 μm, it is difficult to form pores in the coating layer, but the specific surface area is 100.
If it is larger than m ² / g or if the average particle size is smaller than 0.1 μm, it becomes difficult to form a paste and the microporosity of the coating layer is hindered.

The porous thin base sheet is preferably a non-woven fabric or a woven fabric composed of fibers having excellent acid resistance and oxidation resistance, and it is sufficient that a large number of openings are formed between intersecting fibers. In the case of a non-woven fabric, it is usually produced by a dry or wet papermaking method, and preferably has a density of 0.15 to 0.40 g / cm ³ ,
It is preferable that the maximum pore size is 10 to 100 μm. In the case of a woven fabric, a woven fabric having numerous openings through which the paste can pass is used. The material of the fibers may be either natural fibers or synthetic fibers, and as the synthetic fibers, polyolefin fibers such as polyethylene and polypropylene, polyester fibers, acrylic fibers and the like may be used alone or in combination. In particular, polyethylene is particularly excellent in oxidation resistance, and polypropylene fiber is excellent in strength characteristics.
It is preferable to make a base sheet made of a non-woven fabric or a woven fabric by using a core-sheath structure composite fiber using both of them. The thickness of the base sheet is preferably as thin as in the range of 0.05 to 0.20 mm from the viewpoint of mechanical strength and electric resistance.

The above-mentioned desired synthetic fiber and inorganic powder are appropriately blended, and this is mixed with an appropriate amount of water as a medium to form an aqueous paste, which is applied to both sides of the desired porous substrate sheet. Working, pressurizing to form a coating layer having a certain thickness, drying by heating, and further binding between both surfaces of the base sheet by heating and melting the surface of the synthetic fiber and the mixed inorganic powder particles Bonding is performed, and thus, a stable and robust lead-acid battery separator of the present invention having a microporous coating layer having flexibility that does not cause cracks or defects on both sides of the base sheet is obtained. .

A preferred manufacturing example thereof is as follows.
The above synthetic resin 5 to 35 wt.% In the form of dispersion or emulsion, together with 15 to 50 wt.
Prepare an aqueous paste by mixing through 80 wt.% Water.
Next, both surfaces of a porous base material sheet made of this paste are coated so that the dry basis weight is 50 to 150 g / m ² .
Next, the coating layer is pressed from both sides, pressure-bonded to the surface of the base material sheet to form a certain thickness, and then dried by heating,
Further heating to melt the surface of the synthetic resin particles to bind the dry coating layer to the surface of the base material sheet, and at the same time, to bind the particles of the mixed inorganic powder to each other to provide stable and robust microporosity. The lead-acid battery separator of the present invention having a coating layer is obtained. In the above-mentioned production, in the coating and pressing step of the above-mentioned paste, the coating layers on both sides of the base sheet are integrated with each other through the innumerable openings between the fibers in the base sheet. To do. Thus, by heating and drying in this state, the coating layers adhered on both sides of the base sheet are integrally bound to each other through a myriad of holes, and the resistance to peeling is markedly improved. Is obtained.

In the preparation of the paste, it is possible to add an appropriate amount of a thickener to water to form a viscous liquid, and to adjust the flow coatability of the paste to an appropriate level. For example, CM as a thickener
It can be applied as a viscous paste containing 0.1 to 5% by weight of C.

The mixing ratio of the synthetic resin, the inorganic powder and water in the preparation of the paste is preferably 5 to 35 wt.% Of the synthetic resin, 15 to 50 wt.% Of the inorganic powder and 15 to 80 wt.% Of water. If the resin is less than 5 wt.% Or the inorganic powder exceeds 50 wt.%,
Adhesion between the base sheet and the inorganic powder particles becomes poor, while the synthetic resin exceeds 50 wt.% Or the inorganic powder 15
If it is less than wt.%, the microporosity of the coating layer tends to decrease and the electric resistance tends to increase.

The lead-acid battery separator of the present invention thus produced is used for assembling the electrode plate group by interposing between the negative and positive plates, has a low electric resistance, and has a property of preventing permeation of the active material. However, since the coating layer is flexible, a separator excellent in peeling resistance to the surface of the base material sheet can be obtained without cracking or damage due to impact during battery assembly, and
The gas generated during charging of the battery does not accumulate between the surface of the base material and the coating layer, thus providing a long-life lead acid battery with excellent battery characteristics without increasing internal resistance.

The lead-acid battery separator of the present invention is used in the form of a leaf up to this point, and is also used in the form of a bag as described later, and in any case, it is used in a state in which a glass mat is stuck. It may also be used as a leaf-shaped or bag-shaped ribbed separator formed by integrally disposing a plurality of ribs made of synthetic resin or the like on one side or both sides of the dry coating layer. .

Further, in order to make it easier for the paste mixture to enter the inside of the porous thin sheet, the fluidity thereof is adjusted by taking into consideration the fiber diameter of the sheet and the degree of opening obtained by the fibers. The paste may be applied at a pressure of -50 Kg / cm ² , and further pressure may be applied after the application.

FIG. 1 shows an example of a paste coating apparatus used in manufacturing the lead storage battery separator of the present invention and an example of coating the porous base material sheet with the paste, where 1 is The coating tank 2 containing the paste a is
A pair of left and right pressure rolls for paste coating 3 disposed above the guide rolls 3 are guide rolls provided in the coating treatment tank 1. The porous thin substrate sheet 4 is pulled out from a supply drum (not shown) by traction, moved obliquely downward as shown by the arrow, and dipped in the paste a layer in the treatment layer 1, while the paste is applied to both surfaces thereof. After applying a and a,
It is guided vertically upward through the guide roll 3 and drawn upward through a predetermined interval between the pair of paste coating pressure rolls 2 and 2 above the guide roll 3. Thus, at the time of passage, the coating layers a, a on both sides of the base material sheet 4 are pressed from the outer surface by the pair of pressure rolls 2 and 2 to be brought into close contact with the base material sheet 4, and at the same time. Coating layer a having a thickness of
a is formed. Next, this is subjected to a heat drying treatment and a heat binding treatment to the synthetic resin particles to obtain the lead storage battery separator 5 of the present invention. The long separator obtained by the above-mentioned manufacturing method may be passed through a penetrant treatment tank and then dried to perform a penetrant treatment.

FIG. 2 is a side view diagrammatically showing a leaf-shaped separator obtained by cutting the thus manufactured long separator 5 of the present invention into a predetermined length. Dry coating layer 5a fixed by pressure on both sides of the porous substrate sheet 4,
The sheets 5a are connected to one another by opening the numerous holes 4a of the sheet 4.

Next, specific examples of the present invention will be shown. Example 1 As a synthetic resin, an acrylic resin emulsion having a glass transition temperature Tg of 10 ° C. was used as a solid content of 10 wt.
CM as a thickener with 30 wt.% Of diatomaceous earth having an average particle diameter of 2 μm
A paste was prepared by mixing 59 wt.% Of water with 1.0 wt.% Of C added, and then using this as a porous base material sheet, the thickness of the core-sheath structure in which polypropylene was the core and polyethylene was the sheath was 18 μm. 36 g / basis weight created by the card method using the above fibers
m ^2, a thickness of 0.12 mm, was coated using a coating apparatus shown in FIG. 1 on both sides of the nonwoven fabric having a density of 0.30 g / cm ^3, both side surfaces at a pressure of 10 Kg / cm ² by a pair of pressure rolls Pressurize from
A coating layer having a predetermined thickness was formed on both sides of the nonwoven fabric. Next,
After heating and drying at a temperature of 100 ° C., it was heated at a temperature of 120 ° C. to heat-treat the surface of the synthetic resin particles for fusion bonding. Thus, dry basis weight 125 g / m ² , thickness 0.25 mm, density 0.50 g /
A lead acid battery separator of the present invention having a cm ³ was obtained. Next, this was cut into a predetermined length to obtain a leaf-shaped separator having a predetermined size. In addition, the separator was folded in two and both side edges of the coating layers that were overlapped were bonded to each other to form a bag-shaped separator. Example 2 As a synthetic resin, 8 wt.% Of an acrylic resin emulsion having a glass transition point Tg of −10 ° C. and 26.9 wt.% Of diatomaceous earth having an average particle diameter of 2 μm and 0.1 wt.% Of CMC were added as inorganic powders. A paste was prepared by mixing it with 65 wt.% Of water, and the paste was prepared by the card method using a core-sheath structure 18 μm thick fiber with a polypropylene core and a polyethylene sheath.
A non-woven fabric having a thickness of 36 g / m ² , a thickness of 0.12 mm and a density of 0.30 g / cm ³ was coated on both sides using the coating apparatus shown in FIG. Heat drying and heat treatment were performed. Thus, dry basis weight 125 g / m ² , thickness 0.25 m
A separator sheet for a lead storage battery of the present invention having m and a density of 0.50 g / cm ³ was obtained. Example 3 As a synthetic resin, 8 wt.% Of an acrylic resin emulsion having a glass transition point Tg of 30 ° C. and an inorganic powder, an average secondary particle diameter of 2.5 μm and a specific surface area of 30 m ² / g of amorphous silica 26.5 w
A paste was prepared by mixing t.% with 65 wt.% of water containing 0.5 wt.% of CMC, and using this, a polypropylene-core and polyethylene-sheath core-sheath structure 18 μm thick fiber was used. 36 g / m ² with a card method and a thickness of 0.12 m
Both sides of a non-woven fabric having m and a density of 0.30 g / cm ³ were coated by using the coating apparatus shown in FIG. 1, and then dried in the same manner as in Example 1 and heat-treated with a synthetic resin. Thus, a lead storage battery separator of the present invention having a dry basis weight of 125 g / m ² , a thickness of 0.25 mm and a density of 0.50 g / cm ³ was obtained. Example 4 As a non-woven fabric, the basis weight is 32 g / m ² , the thickness is 0.08 mm, and the density is 0.40.
Example 1 was repeated except that the g / cm ³ g / cm ³ was used, and the basis weight was 100 g / m ² , the thickness was 0.20 mm, and the density was 0.50 g / cm ^3.
A lead storage battery separator of the present invention having the above was obtained. Example 5 As a porous base material sheet, the material was made of polypropylene and had a thickness of 18 μm.
Dry basis weight 1 was performed in the same manner as in Example 1 except that the nonwoven fabric was 32 g / m ² , thickness 0.08 mm, and density 0.40 g / cm ^3.
A lead acid battery separator of the present invention having 00 g / m ² , a thickness of 0.20 mm and a density of 0.50 g / cm ³ was obtained. Example 6 As a porous base material sheet, a woven cloth having a basis weight of 50 g / m ² and a thickness of 0.15 mm was prepared by plain weaving using 10 2 denier drawn yarns made of polypropylene. The same procedure as in Example 1 was performed, and the dry basis weight was 120 g / m.
² , a lead acid battery separator of the present invention having a thickness of 0.30 mm and a density of 0.40 g / cm ³ was obtained. Examples 7 to 12 Each of the lead-acid battery separators obtained in Examples 1 to 6 is folded in two, and both side edges thereof are heat-sealed by an ultrasonic fusion machine to form a bag of the present invention. A lead-acid battery separator in the form of a strip was obtained.

Conventional Example 1 Basis weight of synthetic pulp, synthetic fibers and inorganic powder 100 g /
m ^2, thickness 0.25mm the separator sheet 2 sheets of each one side of methyl methacrylate (MMA) emulsion 30 wt.%, amorphous silica 10 wt.%, after applying the water 60 wt.% of the formed by mixed paste Then, the coated surface was overlaid and pressed, and then dried to obtain a comparative separator having a thickness of 0.65 mm. This separator sheet cracked in the coating layer due to the impact when the battery was assembled. Conventional Example 2 Basis weight created by the card method using a core-sheath structure fiber having a core of polypropylene and a sheath of polyethylene and having a thickness of 18 μm
36 g / m ² , thickness 0.12 mm, density 0.30 g / cm ³ Mixing methyl methacrylate (MMA) emulsion 30 wt.%, Amorphous silica 10 wt.%, Water 60 wt.% On each side. The resulting paste was coated, and the coated surface was overlaid, pressed, and dried to obtain a separator sheet having a thickness of 0.40 mm. This separator sheet cracked in the coating layer due to the impact when the battery was assembled. Conventional Example 3 40 wt.% Polyethylene resin, 60 wt.% Silicic acid powder with a specific surface area of 250 m ² / g, and 140 w for this mixture as a pore opening agent
t.% mineral oil is mixed with a mixer, and the mixture is extruded with a twin-screw extruder to have a thickness of 0.25 mm and a sheet width direction of 10 mm.
A sheet having ribs with a height of 0.7 mm and a width of 0.7 mm at intervals was obtained. 125 wt.% Of the added amount of mineral oil of 140 wt.% Was extracted from the sheet with trichlorethylene to obtain a microporous separator sheet for lead storage battery, which has been conventionally used for comparison. Next, a bag-shaped lead storage battery separator was obtained by a known method. Conventional Example 4 The lead-acid battery separator obtained in Conventional Example 1 is
The bag-shaped lead storage battery separator was obtained by folding it in half and heat-sealing the overlapped side edges with an ultrasonic fusion machine. Conventional Example 5 The lead storage battery separator obtained in Conventional Example 2 is
The bag-shaped lead storage battery separator was obtained by folding it in half and heat-sealing the overlapped side edges with an ultrasonic fusion machine.

With respect to the separators of the present invention of Examples 1 to 6 of the present invention and the conventional separators of Conventional Examples 1 to 3, separator properties such as electric resistance, maximum pore size, and oxidation resistance, as well as rigidity and peel strength were measured. Further, a lead acid battery using each separator was prepared and a life test of the lead acid battery was performed. In addition, stains on the batteries that underwent this life test were observed. Further, bending tests were conducted on the bag-shaped separators of the present invention of Examples 7 to 12 and the bag-shaped separators of Conventional Examples 3 to 5 described above.

The rigidity test was conducted according to JIS P 8215. For the peel strength test, each sample separator was cut into 5 x 5 cm, double-sided adhesive tape was attached to both front and back sides, and one side was fixed to the table of a universal tensile tester (auto strain) and fixed on the other side. A square pyramid having a bottom surface of 5 × 5 cm was attached to the surface of No. 1, and the hook provided on the upper portion of the square pyramid was fixed to the crosshead of the universal tensile test to perform the tensile test. In the present invention and the comparative separator, the value when peeling between the porous substrate sheet and the coating layer occurs, and in the conventional separator, when peeling between the separator base paper and the coating layer occurs The value was taken as the peel strength. As a life test of the lead storage battery, a heavy load life test and a light load life test were performed according to JIS D 5301.

The above measurement and observation results are shown in Tables 1 and 2 below.
It was as shown in.

[0025]

[Table 1]

[0026]

[Table 2]

As can be seen from Tables 1 and 2 above, when compared with Conventional Examples 1 and 2, Examples 1 to 12 of the present invention have rigidity one digit smaller and good flexibility, and No cracking or chipping due to impact occurred during handling. Also, the peel strength was significantly improved as compared with Conventional Examples 1 and 2. In addition, in the heavy load life test and the light load life test, which are life characteristics, in Conventional Examples 1 and 2, a short circuit occurred in the separator, resulting in a short life. The cause is that the paste does not penetrate into the non-woven fabric, so the gas generated when the lead acid battery is charged accumulates in the voids inside the non-woven fabric sandwiched by the paste, and the dense layer formed by the paste peels off, increasing the internal resistance of the battery. This is because the charge and discharge cannot be performed sufficiently, whereas the embodiment of the present invention does not cause such gas accumulation and peeling, and thus the life is improved. On the other hand, in Conventional Example 3, during the heavy load life test and the light load life test, the inside of the battery case was contaminated due to the generation of viscous substances, and it was difficult to confirm the electrolysis level. Further, after the end of the life test, clogging of the liquid plug filter increased its ventilation resistance to 5 times the initial value.

A common porous substrate sheet was used, various separators were prepared by varying the basis weight of the dry coating layers formed on both sides of the sheet, and the results were tested for electrical resistance and oxidation resistance. When the basis weight is less than 40 g / m ² , the electric resistance value is small, but the oxidation resistance is remarkably poor at 30 hr / sheet, and conversely, when the basis weight exceeds 180 g / m ² , the oxidation resistance is 350 hr / sheet.
It was found that it was not preferable because the electric resistance improved to 0.0020 Ω · 100 cm ² / sheet.

Further, in preparing the paste, various types of separators were tried by changing the compounding amount and the compounding ratio of the synthetic resin and the inorganic powder, but when the synthetic resin was too much, the dry coating layer had a microporous structure. If the amount of the inorganic powder is too large and the amount of the inorganic powder is too large, the paste loses fluidity and the coating operation becomes difficult. In order to smoothly perform the paste coating operation and to obtain a dry coating layer having good microporosity, it is found that the range of synthetic resin 5 to 35 wt.% Inorganic powder 15 to 50 wt.% Is preferable. It was.

As is apparent from the above, since there is no inconvenience such as peeling, cracking or cracking of the coating layer due to bending, the lead storage battery separator of the present invention can be obtained by the production method of the present invention shown in FIG. The long lead-acid battery separator thus prepared is provided with a plurality of parallel synthetic resin ribs on at least one side of the same or its coating layer, and then cut into a predetermined size to obtain the leaf shown in FIG. Not only a separator product having a shape of a bag, but also a separator product having a bag shape can be obtained. That is, the sheet-shaped separator is folded in two by an ordinary bag-shaped processing means, and the anode plate or the cathode plate is sandwiched between the opposite side edges of the coating layer by using an ultrasonic fusion machine or a mechanical seal machine. Can be tied up. in this case,
Since the thermoplastic synthetic resin is uniformly mixed in the overlaid coating layers, both side edges thereof are easily and quickly fused by heating, so that a so-called heat-sealed bag-shaped separator can be obtained smoothly and quickly. . Further, by applying a thermoplastic resin having a melting point of 90 to 150 ° C. to a thickness of 0.01 to 0.20 mm on both ends of 3 to 20 mm of the porous base material sheet of the present invention, and forming a bag-like shape by overlapping these parts. The fusion strength can be further improved.

[0031]

As described above, according to the present invention, a porous substrate sheet is coated with an aqueous paste obtained by mixing a synthetic resin and an inorganic powder and dried to integrally form a microporous coating layer. In this regard, since the synthetic resin used is one that takes flexibility into consideration, flexibility is imparted to the coating layer, and cracking and chipping due to impact during work such as battery assembly are prevented. Further, since the coating layers on both sides of the base sheet are connected to each other through the innumerable openings of the base sheet, a separator with increased peel strength is obtained. Furthermore, the separator of the present invention having such a structure eliminates the above-mentioned drawbacks of the conventional separator without the gas generated during battery charging remaining between the base sheet and the coating layer. It has the effect of extending the life of the lead acid battery. in this case,
When the dry basis weight of the coating layer is 50 to 150 g / m ² , a separator having low electric resistance and improved oxidation resistance is obtained. Further, according to the method for producing a lead storage battery separator of the present invention, the synthetic resin is 5 to 35 wt.% And the inorganic powder is 15 to 50 w.
By mixing t.% with 15 to 80 wt.% of water, the mixed paste can be well coated on both sides of the porous substrate sheet, and a coating layer formed under pressure on both sides thereof. By heat-drying, a separator having flexibility, excellent peeling resistance, acid resistance, oxidation resistance, and low electric resistance is surely brought, and as an inorganic powder, an average particle size of 0.1 to 5 μm and a specific surface area of 0.1 to Pore size when using 100 m ² / g
A microporous coating layer of 0.1 to 10 μm can be obtained. Further, as the base material sheet, a thickness of 0.05 to 0.20 mm, a density of 0.15
When using 0.40 g / cm ³ and a maximum pore size of 10 to 100 μm, a lead storage battery separator having the above-mentioned various excellent properties can be obtained. Furthermore, since the storage battery separator of the present invention has the above-described configuration and does not contain oil, there is no viscous material that elutes or precipitates even after repeated charge and discharge during initial charge or use of a lead storage battery. , The inside of the battery case may become dirty and the electrolyte level may not be confirmed, or the liquid plug and its filter may become clogged and degassing may not be possible, increasing the internal pressure of the lead acid battery and causing a danger to the user. Absent.

When the above-mentioned lead-acid battery of the present invention is processed into a bag shape, even if it is bent, there is no inconvenience such as peeling, cracking or cracking of the coating layer from the base sheet. Since both side edges can be superposed and bound by heat sealing or the like, a good bag-shaped lead storage battery separator can be obtained without manufacturing loss. Also, since no organic solvent is used in the manufacturing method, there is a risk of explosion and fire,
It has an effect that a leaf-shaped or bag-shaped separator can be manufactured smoothly without environmental damage.

[Brief description of drawings]

FIG. 1 shows a side view of a coating apparatus showing an example of a method for manufacturing a lead storage battery separator of the present invention.

FIG. 2 shows a side view of the lead-acid battery separator of the present invention.

[Explanation of symbols]

1 Coating Treatment Layer 2 Pressurizing Roll 3 Guide Roll 4 Porous Thin Base Sheet 4a Opening 5 Lead Acid Battery Separator 5a Coating Layer a Paste

Claims (8)

[Claims] 1. A microporous coating consisting of a mixture of a synthetic resin and an inorganic powder, which is integrally connected to each other on both sides of a porous thin base sheet through a myriad of openings in the base sheet. A lead-acid battery separator with an integral layer. 2. A microporous coating comprising a mixture of a synthetic resin and an inorganic powder, which is integrally connected to each other through the numerous holes of the base sheet, on both sides of the porous thin base sheet. A lead storage battery separator formed by integrally forming layers and forming a bag shape. 3. The lead acid battery separator according to claim 1, wherein a plurality of ribs are provided on at least one surface of the coating layer. 4. The coating layer has a dry basis weight of 50 to 150 g / m ^2.
The lead-acid battery separator according to claim 1, 2, or 3. 5. The porous thin substrate sheet has a thickness of 0.05 to
0.20 mm, density 0.15 to 0.40 g / cm ³ , maximum pore diameter 10 to 100 μ
The lead-acid battery separator according to claim 1 or 2, which is made of a nonwoven fabric of m. 6. Synthetic resin 5 to 35 wt.% And inorganic powder 15 to 50 w
t.% and water 15 to 80 wt.% as a medium to prepare a paste mixture, which is applied to both sides of the porous base material sheet to form a coating layer, which is then dried and bound by heating. A method of manufacturing a separator for a lead storage battery, the method comprising: 7. The synthetic resin in the form of a dispersion or emulsion, a particle size of 0.1 to 5 μm, and a specific surface area of 0.1 to
The method for producing a lead-acid battery separator according to claim 6, wherein a paste mixture is prepared by mixing 100 m ² / g of inorganic powder. 8. The separator obtained by the method for producing a lead storage battery separator according to claim 6 or 7, without or with the step of disposing a plurality of ribs on at least one coating layer surface, A method for producing a separator for a lead storage battery, which comprises folding and folding, and binding both side edges of the polymerized coating layer to each other to form a bag.