JPS62252066A - Separator for storage battery - Google Patents

Abstract

PURPOSE:To increase strength, electrolyte absorbing capacity, electrolyte retention capacity, and heat sealing ability by forming a separator with glass fiber, water absorbing synthetic fiber, and thermoplastic organic fiber. CONSTITUTION:A separator consists of glass fiber, water absorbing fiber, and thermoplastic organic fiber. As the glass fiber, alkali-containing glass fiber having good acid resistance is preferable. As the water absorbing fiber, acrylic fiber in which water absorption treatment is applied on the surface is preferable. As the thermoplastic organic fiber, polyester is suitable from the standpoint of acid resistance and oxidization resistance. Preferable mixing ratio is 30-79wt% glass fiber, 1-20wt% water absorbing fiber, and 20-60wt% thermoplastic organic fiber. The contents of water absorbing fiber and thermoplastic organic fiber are preferable to control to 70wt% or less based on the total fiber weight.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a separator for storage batteries, and particularly to a separator for storage batteries that has good strength, liquid absorption and liquid retention properties, and also has excellent heat sealability.

[Conventional technology and prior art] As a separator for a storage battery containing glass am,
Various types have already been proposed and put into practical use, but they can be broadly classified into the following three types. That is, (O) containing mainly short glass fibers, (c) containing powder held in short glass fibers,
Made by mixing and molding short glass fibers and synthetic fibers.

It is.

Among these, the one mainly composed of short glass fibers has a short m-line length and is wood-loving, so if it contains a large amount of short glass fibers with a small diameter, Although it has excellent liquid retention and liquid absorption properties, which are the basic performance of storage batteries, the small diameter short glass fibers are expensive, so the separators made from them are also expensive. Furthermore, a separator formed without using an organic binder has low tensile strength and low rigidity, making it difficult to assemble a storage battery. Furthermore, when molding is performed using an organic binder, when the battery is incorporated into a storage battery and used, the binder may dissolve into the electrolyte, which may deteriorate the performance of the storage battery.

■Glass m#! For example, there is a paper made of a mixture of powder and powder, as described in JP-A-206046S'F. Although this paper has good liquid absorption properties, the powder does not separate from the separator. A#: There is a problem that it easily falls off and the medium tensile strength is low.

On the other hand, as for the paper made by mixing 11 ml of short glass and synthetic fiber,
No. 22531, JP-A No. 56-99968, Special 1-use closure 5
There are those described in Japanese Patent Publication No. 3-136632 and Japanese Patent Publication No. 58-663, and these have the advantage of being easy to assemble a storage battery because of their high mechanical strength (tensile strength, rigidity, etc.). In addition, mechanical properties such as strength and rigidity are improved in the separator production process by raising the temperature to 160 to 180°C for drying, which improves mechanical properties such as synthetic fibers and glass fibers. This is thought to be due to the fact that the fibers are bonded together by thermal fusion.

However, although separators mixed with synthetic fibers have excellent mechanical properties, synthetic fibers have lower wood-philicity than glass fibers, so they have poor absorption and retention of sulfuric acid solutions. It has its drawbacks. In other words, in the case of a separator made only of glass fibers, the sulfuric acid solution is absorbed and retained due to the capillary phenomenon between the glass fibers, but when synthetic fibers are used, the sulfuric acid solution absorbs and retains the liquid because synthetic fibers are hydrophobic. This results in poor wettability and impaired liquid absorption and retention.

In addition, in separators containing synthetic la and il, the synthetic fibers are heated and fused and become glued, making it difficult to moisten when absorbing sulfuric acid solution, so the repulsive force (restoring force) of the separator There is also the problem of a decrease in

In order to solve these problems, the applicant has proposed the following:
Among the storage IT Ikeda separators that contain glass fibers and synthetic fibers, we first filed a patent application for the storage Asahikawa separator that uses synthetic fibers as water-absorbing synthetic fibers (patent application filed in 1986-2).
8004, hereinafter referred to as the "prior application").

+11+ As mentioned above, it has been conventional practice to mix synthetic fibers into the energy storage Asahikawa separator to improve the mechanical strength of the separator, and acrylic fibers with strong acid resistance are widely used as the synthetic fibers. There is. However, synthetic fibers such as acrylic fibers have less wood-philicity than glass fibers, and if they are mixed in a large amount, they will reduce the liquid retention properties of the separator, whereas if they are mixed in a small amount, they will not be able to improve the mechanical strength. The effect becomes smaller.

On the other hand, when water-absorbing synthetic fibers are used as in the previous application, the water-absorbing synthetic fibers absorb the electrolyte of the storage battery and swell, so ordinary synthetic fibers cannot be used. It is possible to prevent a decrease in liquid absorption and liquid retention properties that occur during use.

Furthermore, the mechanical properties of the separator are greatly improved due to the reinforcing effect of the combined use of synthetic fibers.

By the way, plate-shaped separators are common as the form of Ikeda separators, but in order to prevent short circuits of the electrode plates due to the formation of electrode plate parts that are not protected by the separator, The bag-like separator that wraps around the entire horizontal board is sweating.

Therefore, as a separator pot suitable for manufacturing a bag-like separator, glass fibers and heat n (plastic organic fibers) are combined so that the clay of the organic fibers is 50% or more of the total weight of both fibers.
A bag-shaped separator mat is known (Japanese Patent Application No. 1983-
175069).

Specifically, the mat described in Japanese Patent Application No. 55-175069 is heat-sealable due to the combination of 8 plastic organic fibers, so the mat is folded and stacked, and the overlapped portion is formed using a high-frequency heat sealing machine or the like. A bag-like separator can be produced by heat-sealing the peripheral edge.

[Problems to be Solved by the Invention] However, in a separator made of glass fiber and thermoplastic organic fiber, as in Japanese Patent Application No. 55-175069,
As mentioned above, since the hydrophilicity of general organic fibers is inferior to that of glass fibers, there is a problem that the separator cannot obtain sufficient liquid retention and water absorption properties.

Conventionally, #A is a bag-shaped separator with good sealing properties.
No separator has been proposed that is suitable for construction and also has extremely high strength, liquid retention, and liquid absorption properties.Therefore, there is currently a strong demand for a separator that has these excellent properties. There is.

That is, in recent years, machines have been increasingly used to assemble batteries, and when assembling using machines, the separator is required to have considerable strength. Furthermore, in the field of electrical and mechanical products, there is a constant pursuit for products to be more compact and have higher performance, and separators are also desired to have even greater liquid absorbing and liquid retaining properties.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention was made to provide a separator for storage batteries that has good strength, liquid absorption and liquid retention properties, and also has excellent heat sealability. A separator for a storage battery, comprising glass fiber, water-absorbing synthetic fiber, and thermoplastic organic #IA fiber.

The main points are as follows.

The configuration of the present invention will be explained in detail below.

The fibers constituting the separator of the present invention are glass fibers, water-absorbing synthetic fibers, and thermoplastic organic fibers.

As the glass fiber, alkali-containing glass fiber with good acid resistance is preferable. When alkali-containing glass fiber is used, a water glass-like substance is generated on the surface of the glass fiber during the papermaking process of the binding process, and this water glass-like substance The fibers are bonded together due to their adhesive properties.

Glass fiber is suitable for separators in terms of liquid retention and water absorption.
It is preferable that the average diameter is 44 m or less, and in this case, the entire amount may have a small diameter, for example, an average diameter of 2 gm or less, and such a small diameter fiber and an average diameter of 2 gm or less may be used.
It may also be used in combination with medium-thin diameter fibers exceeding 41 Lm.

The preferred average diameter of the small diameter glass fibers is 0.5 to 1.0.
pm, more preferably 0.6 to 0.9 gm. The diameter is 1. If it exceeds Opmt, the pore diameter of the separator becomes large, and conversely, if it becomes smaller than 0.5 pm, the manufacturing cost becomes high.

The preferable content of this thin glass fiber is 70% by weight or more of the weight of the glass fiber, particularly preferably 75% or more of the weight of the glass fiber.If the content is less than 70%, the liquid absorbency and liquid retention are reduced. This is because they are more likely to lack sex.

Further, the average length of this small diameter glass fiber is preferably 7 to 7.
50 mm, more preferably 10 to 40 mm.

Such small-diameter glass fibers can be manufactured by the FA method (flame U:), centrifugation method, or other short glass fiber manufacturing methods.

In the present invention, the average diameter of the glass fibers is as follows.

Photographs were taken using an electron microscope at three locations on the sample, and the diameters of each of the 20 fibers were measured at 0. It is calculated by measuring in lILm and taking the average value.

When medium-sized glass fibers are used, the preferred average diameter is 2.0 to 4.0 m, particularly 2.0 to 3.54 m.
It is. By blending medium- and small-diameter glass fibers, it is possible to reduce the number of small-diameter glass fibers, which is advantageous in terms of cost.

A suitable range of the composition of the glass m-fiber will be explained next.

As mentioned above, the glass fibers constituting the separator of the present invention are preferably those having a 1U alkali-containing silicate glass composition because they form water glass on the surface and exhibit adhesive properties. Since it is used for many purposes, those with good acid resistance are preferably used. This degree of acid resistance is average fiber! It is also desirable that the weight loss when measured according to JIS C-2202 is 2% or less in the state of glass fiber with a diameter of 1#L or less.

The composition of such glass fiber is 60 to 7 in terms of weight ratio.
5% S i O2 and 8-20% R20 (N a
20. Mainly contains alkali metal oxides such as R20), but S i O2+ R20 is 75 to 90%
) In addition, for example, Cab, MgO.

Rz Ox, AM? 03, ZnO1Fe20x and the like.

An example of a preferable alkali-containing silicate glass is shown in Table 1 below.

Table 1 As the water-absorbing synthetic fiber used in the present invention, it is preferable to use acrylic fiber or the like whose surface has been subjected to a super-absorbent treatment.
Specifically, Lanseal-F (manufactured by Nippon Exlan Kogyo, trade name) and the like may be mentioned. Lanseal-F is applied to the surface of acrylonitrile fibers by 20 to 30% of the total ff1ffi.
It is a super absorbent organic fiber with a diameter of about 15 #Lm and an average length of 3 to 20 mm, which holds polyacrylic acid.

In addition, as the 8-plastic force machine fiber, polyolefin type,
Organic fibers such as acrylic fibers can be used, but polyester fibers are suitable because of their acid resistance and oxidation resistance. It is preferable that the thermoplastic material has an average diameter of 30 gm or less and an average length of 3 to 20 mm.

In the uninvention, the blending ratio of these glass MAm, water-absorbing synthetic fibers and 8TT] plasticity r*mla is 30-79% glass fiber, 1-20% water-absorbing synthetic fiber,
Heat 11 plastic organic fibers #I 20-60% binding, water-absorbing synthetic fibers and 8n [plastic organic fibers are 70i' [1% or less] of the total weight of all fibers constituting the separator. It is preferable to do so.

Such a separator for power storage and other uses of the present invention can be manufactured by a method similar to the method for manufacturing a separator in which water-absorbing synthetic fibers and thermal Ti (plastic organic fibers) are blended, and ordinary synthetic lam is blended. That is, in J packaging using alkali-containing silicic acid 1-1 glass fiber Mk as glass fiber and thermoplastic organic fiber, for example, pH (df2.5-3 Disperse the fibers in water kept at a temperature of .5 for a certain period of time, for example 5 to 20 minutes, using a water jet disperser etc., without breaking the fibers as much as possible.
This is wet-formed to form an adhesive layer, perhaps a water glass layer, on the surface of the glass fiber, and then heated to a predetermined temperature, for example 80 to 180°C, to form a glass #
It can be obtained by gluing the a-fibers together with wood glass on their surface.

In addition, water-absorbing synthetic fibers and thermoplastic organic fibers mixed as part of the fibers may also be used in the post-process heat treatment process (e.g. drying process).
It exerts a molding or adhesion effect in the process, 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.

It is also possible to add water glass during the dispersion of fibers in water or during the papermaking process to promote adhesion. In addition to water glass, similar inorganic adhesives can also be used. Something like this: 5ilpap7
Examples include those commercially available under the trade name 00. In addition, a dispersant may be used for dispersion, and
By spraying dialkyl sulfosuccinate onto a wet-paper-formed fiber paper product, for example, a fiber paper product on a paper-making conveyor, the dialkyl sulfosuccinate is attached to the glass fibers in an amount of 0.005 to 10% by weight. The hydrophilicity of the separator can improve the liquid retention properties of the separator. Instead of spraying the dialkyl sulfosuccinate as described above, the dialkyl sulfosuccinate may be mixed into the dispersion water in the papermaking tank.

The separator for a storage battery of the present invention preferably has a liquid absorption rate of 70 mm/5 minutes or more.

[Function] By blending thermoplastic organic fibers, the separator can be heat-sealed, and bag-shaped separators can be easily manufactured.

Moreover, in the present invention, along with such thermoplastic organic fibers, it absorbs the electrolyte of the storage battery and swells, thereby preventing the decrease in liquid absorption and liquid retention that occurs when ordinary synthetic fibers are used. Since the separator contains liquid absorbent synthetic fibers that can absorb liquid, the liquid absorbing and liquid retaining properties of the separator can be improved.

In addition, in the separator of the present invention, these liquid-absorbing synthetic fibers and 8nT plasticity ammonium are heated and melted during drying after papermaking during the separator manufacturing process to increase the strength of the separator and significantly improve its mechanical properties. can be improved. Therefore, the required amount of water-absorbing synthetic fibers for strength can be reduced due to the reinforcing effect of thermoplastic organic fibers. In this case, since thermoplastic organic fibers are cheaper than liquid-absorbing synthetic fibers, material costs can be reduced.

[Example 1 Examples and comparative examples will be described below.

Examples 1 and 2, Comparative Example 1.3 The constituent fibers of the composition shown in Table 2 were put into water, stirred and dispersed using a water jet disperser, and sulfuric acid was added to reduce the pH of the water.
H was set to 2.7 and held for about 10 minutes. Then, papermaking was carried out and heated to 150° C. to produce a mat-like electric storage Asahikawa separator.

Table 2 shows the results of measurements of loss on ignition, liquid absorption rate, tensile strength, maximum pore diameter, and heat sealability of this separator.

From Table 2 Table 2, the following is clear. That is, when only thermoplastic organic fibers are added (Comparative Example 1.2), heat-sealability can be obtained, but there are problems with strength and liquid absorption. On the other hand, in the case of the present invention, in which thermoplastic organic fibers and water-absorbing synthetic fibers are blended, sufficient heat-sealing properties can be obtained, and the strength and liquid-absorbing properties are also extremely high.

In addition, ml in Table 2, ! The fibers of No. 5 are as follows.

Moon Glass mmA: Group 1 & = ffG1 Table 17)
('') Average diameter = 0.8 m Average length = l Omm t2 Glass TA fiber B: Composition = (c) in Table 1, f
Uniform diameter = 0, 57Lm Average length = 15mm 03 Water-absorbent synthetic m fibers: Super water-absorbent synthetic fibers (11 made by Exlan Engineering X).

Product name: Lanseal-FJ) House 4 Polyester fiber #I: Melty (4080) (3
Denier, 10 mm) (manufactured by Unitika) Book 5 Polyethylene fiber: Average diameter 20 mm Average length 1
5 mm Furthermore, the measurement methods for these characteristic values in Examples and Comparative Examples are as follows.

■ Thickness (mm) Measure the sample while pressing it with a load of 20 kg/cm' in the thickness direction. (, IS G-2202)■
Fabric weight (g/g) This is the value obtained by dividing the sample weight by the sample area.

■ Density (g/Cm'') 20 to area (S) of sample (weight W) lOcmXlOcm
When T is the thickness of the sample when a load of kg is applied, it is expressed as a value given by the formula: W/ (SxT) (g/cm').

■ Loss on ignition (%) Heat the sample in air to 600°C until it reaches a constant weight, and calculate the loss by dividing the weight by the original weight of the sample.

(Φ Liquid absorption rate (m m / 5 minutes) It is determined by holding the sample upright and immersing its lower part in a dilute sulfuric acid solution with a ratio of 11L1.3, and measuring the liquid level that rises over time after 5 minutes.

■ Tensile strength (g/15mm width) Find the value of the external force (g) when pulling both ends of a 15mm wide sample and causing it to break, and divide by the thickness (mm).
Values are expressed per 15 mm width and 1 mm thickness.

■ Maximum pore size (pLm) Immerse the sample piece in a methanol solution for 30 minutes or more, set the sample in the sample holder of a commercially available maximum pore size measuring device, and pour 10 to 5 cc of methanol from the top with a pipette. Flow air gently, read the air pressure when bubbles are generated from methanol, and use a formula to determine the maximum pore diameter.

(Φ Heat sealability (peel strength (g/15mm width)) Two samples with a width of 15mm are stacked and heat-sealed using a heat sealing machine, and the edge of each sample is pulled to determine the temperature at which peeling starts. Table 1. Effects of the Invention As detailed above, the separator for storage batteries of the present invention is made by blending water-absorbing synthetic fibers and thermoplastic organic fibers.

■ Heat sealing is possible by blending thermoplastic organic fibers, and a bag-shaped separator can be easily obtained by thermal fusion using the heat sealing method.

■ Water-absorbing synthetic fibers and thermoplastic organic fibers provide an extremely excellent reinforcing effect and extremely high mechanical strength.

(2) Water-absorbing properties Due to the liquid-absorbing properties of synthetic fibers, their liquid-absorbing and liquid-retaining properties are significantly improved.

(2) Since the amount of water-absorbing base II and fibers can be reduced, the cost of male material can be reduced.

It has excellent effects such as

As described above, the separator of the present invention is easy to manufacture as a bag-like separator, and has high tensile strength and rigidity, making it easy to assemble a storage battery. Since it is possible to reduce the cost of storage batteries,
The target JT III level 1 is extremely high.

Claims (7)

[Claims] (1) A separator for a storage battery characterized by containing glass fiber, water-absorbing synthetic fiber, and thermoplastic organic fiber. (2) The separator for a storage battery according to claim 1, wherein the content of the water-absorbing synthetic fiber is 1 to 20% by weight of the total amount of fibers constituting the separator. (3) The separator for a storage battery according to claim 1 or 2, wherein the content of the thermoplastic organic fiber is 20 to 60% by weight of the total amount of fibers constituting the separator. (4) Any one of claims 1 to 3, wherein the total content of water-absorbing synthetic fibers and thermoplastic organic fibers is 70% by weight or less of the total weight of the fibers constituting the separator.
A separator for storage batteries as described in . (5) The storage battery separator according to any one of claims 1 to 4, which contains glass fibers with an average diameter of 4 μm or less in an amount of 30 to 79% by weight based on the total weight of the fibers constituting the separator. . (6) The separator for a storage battery according to any one of claims 1 to 5, wherein the thermoplastic organic fiber is a polyester fiber. (7) The separator for a storage battery according to any one of claims 1 to 6, which has a liquid absorption rate of 70 mm/5 minutes or more.