JPH0815070B2 - Separator for lead acid battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lead storage battery separator used for automobiles, electric vehicles, etc., which can be continuously produced with a glass mat having particularly low electric resistance and heat resistance. A low-cost lead-acid battery separator is provided.

Conventional technology and its problems In recent years, in addition to being thin and excellent in acid and oxidation resistance, automotive battery separators have (1) lower electrical resistance, (2) excellent heat resistance, and (3) activity. There is a growing demand for materials that are excellent in holding power and inexpensive.

Here, the separator (1) having a low electric resistance is due to the demand for a battery having further excellent low-temperature high-rate discharge performance,
Regarding the heat resistance of (2), batteries are often used at high temperatures due to the narrowing of the engine room, and (3) is more effective in preventing the active material from falling off due to vibration while the vehicle is running. There is a demand for inexpensive and other functions to perform.

Conventional separators include (a) a paper-making separator made by applying a dry-process glass mat to a paper-making sheet made of polyethylene fibers, inorganic powder, and a binder by applying adhesive in two strips, (b) glass fiber, polyester fiber,
There is a separator or the like which is made from an inorganic powder as a main component and is provided with an armory on one side.

However, these separators are no longer able to satisfy the above requirements. That is, since the separator (a) is laminated with a glass mat obtained by a dry cotton spreading method, which is expensive after papermaking, the total cost as a separator is high. Further, since polyethylene fibers are used, there is a drawback that the wettability with a dilute sulfuric acid electrolytic solution is poor and the gas releasing property is poor. Further, in the separator (b), the surface contacting the anode is a rib, and there is a defect that the function of preventing the active material from falling off is lacking and the seismic resistance is poor.

OBJECT OF THE INVENTION The present invention has been made in view of the above points, and is inexpensive with a glass mat that is thin and has excellent acid resistance and oxidation resistance, extremely low electric resistance, excellent heat resistance, and excellent continuous productivity. A new lead-acid battery separator is provided.

In order to achieve the above object, the present invention provides acid resistance, oxidation resistance,
Glass fiber and silica powder with excellent heat resistance and excellent wettability with dilute sulfuric acid electrolyte, and a web layer wet-fabricated with or without synthetic fiber such as polyester fiber, or not bonded with a binder A lead-acid battery separator is characterized in that two layers of wet-fabricated glass fiber layers are bonded and integrated with the entire surface of the two-layer sheet with the same binder.

Example Hereinafter, details of an example of the present invention will be described with reference to the drawings.

FIG. 1 is a side view of an embodiment of the present invention. Reference numeral 1 is a separator of the present invention in which a wet papermaking web layer 2 and a glass fiber layer 3 are entirely bonded by a binder.

FIG. 2 is a side view of a conventional separator. Reference numeral 4 denotes a separator including a web layer 5 and ribs 6 formed on the surface thereof.

3 and 4 show a front view and a top view of a conventional separator. Reference numeral 7 denotes a separator which is laminated with the web layer 8, the glass mat 9 obtained by the dry method, and the adhesive 10 applied in two rows in the vertical direction. FIG. 5 shows a side view of another embodiment of the present invention. Reference numeral 11 is a row of protrusions provided on the web surface.

Example 1 The web layer and the glass fiber layer shown in Table 1 were formed into a sheet and superposed on each other, and then the fibers of the glass fiber layer were bound together with the acrylic binder containing dialkylsulfosuccinate and the glass of the web layer. The fibers, silica, and polyester fibers are bound to each other, or the glass fiber layer and the web layer are laminated and bonded at the same time to perform integration, and the thicknesses of the web layer and the glass fiber layer are respectively 0.25 mm and 0.
A 55 mm glass matted separator was obtained.

 The respective characteristics are shown in Table 1.

The separators shown in Compositions (a) to (d) have low electrical resistance and excellent oxidation resistance, and have the mechanical strength necessary for the battery production process (for example, the rigidity of the stacking stack, the cracking during bending). Durability).

Also, assemble a battery using these separators,
When the life was evaluated at a high temperature of ℃, it was found that the life was 1.1 to 1.2 times longer than that of the conventional separator. Regarding the discharge performance at low temperature, for example, cold cranking ampere, it is 10
It was confirmed that it increased by ~ 15%.

It has been found that the compositions (e) to (h) are not preferable for these separators because of defects caused by the compositions.

That is, since glass fiber having a large fiber diameter is used in the composition (e), the pore diameter becomes larger than in (a) to (d), and the oxidation resistance is not good. It has been found that increasing the amount of silica powder to prevent this increases the electrical resistance, which is outside the scope of the present invention.

The composition (f) has a smaller amount of silica powder than the composition of (a), but lacks the denseness of the pores, and since the effect of expecting the complexity of the pore path due to the silica powder is lost, the oxidation resistance is not improved. It has drawbacks.

The composition (g) is a composition in which the amount of the silica powder is excessively larger than that of the composition (a), but there is a drawback that the electric resistance increases too much because the silica powder is too clogged. In addition, since there are few fibers, the strength at the time of bending is low, and silica easily falls off.

The composition (h) is a composition in which the polyester fiber is larger than that in the composition (a), but since it is a composition containing a large amount of organic fibers, the stability under high temperature is poor and the high temperature life performance is not good.

Example 2 A web which was wet-paper-formed with the composition shown in Table 1 (a) after making a glass fiber layer of a wet paper-making type which was pre-bonded with an acrylic binder of 10% by weight of the glass fiber layer shown in Table 1. The glass fiber layer was overlaid on the layer, and the entire surface of the two-layer sheet was adhered and integrated with the acrylic binder to obtain a separator.

Since this material has a binder applied twice to the glass fiber layer, it has excellent binding properties between glass fibers, maintains its shape as a glass mat by the end of the battery life, and maintains the effect of preventing the active material from falling off for a long time. I found out.

Example 3 Wet papermaking of a web layer with the composition (b) shown in Table 1,
A glass fiber layer was wet-fabricated and laminated in the same manner as in Example 1, immersed in an acrylic binder, passed through a calender roll having grooves at 0.1 mm and 15 mm intervals, and dried and cured to form row-shaped projections on the web layer surface. A separator with a glass mat provided with was obtained. This was a separator with excellent stacking and sliding properties during the production of battery electrode groups.

The average diameter of the glass fibers used in the web layer of the present invention, the weight% of each material, the numerical values selected to satisfy the characteristics and mechanical strength of the resulting separator, productivity, cost Shows.

0.8 as the average diameter of the glass fiber used for the web layer
The optimum value is ~ 3.5μ, and if it is thinner than this, the glass fiber itself becomes expensive and unsuitable. If it is thicker than this, the pore size becomes large as shown in Example 1, and the oxidation resistance is not good.

As the silica powder, fine particles of inorganic silica such as dry method SiO ₂ , wet method SiO ₂ and diatomaceous earth can be used, and among them, those having a specific surface area of 100 m ² / g or more are preferable. This is because the wettability with acid is good and the larger the specific surface area is, the finer the powder becomes, the more excellent the dispersion stability in water is.

The ratio of the glass fiber to the silica powder of the web layer is 23 to 43% by weight as the most preferable weight ratio satisfying the requirements for the electrical resistance, oxidation resistance and mechanical strength of the present invention, respectively, as shown in the examples. It is in the range of 57 to 77% by weight.

As synthetic fibers such as polyester fibers to be mixed and mixed therewith, synthetic fibers having excellent acid and oxidation resistance such as polyethylene synthetic pulp and polyacrylonitrile fibers can be applied, and the mixing ratio is preferably 0 to 15% by weight.

The density of the web layer is preferably 0.2 to 0.4 g / cm ^{3 in} order to prevent the oxidation resistance from being lowered due to being too rough and the electric resistance from being increased due to being too dense.

The average diameter of the glass fiber used for the glass fiber layer is 10 to 20μ, and if it is thinner than this, the cost will be higher, the elasticity as a glass mat cannot be expected, and if it is thicker than 20μ, it will be in the working process. Then, obstacles such as getting into contact with the human body will appear. 13 as the average diameter
About μ is most preferable for wet papermaking. The amount of the binder is preferably 10 to 20% by weight in order to secure the minimum binding property of the glass fibers and to suppress the increase in the electric resistance only in the glass fiber layer due to the excessive amount. Similarly, the density is optimally 0.17 to 0.25 g / cm ³ .

The acrylic binder used for the entire adhesion of the web layer and the glass fiber layer and the acrylic binder used when only the glass fiber layer needs to be subjected to the binder treatment in advance may be different or the same. . However, it is more preferable to use the same acrylic binder for both of them because there are advantages such as improved productivity.

Since the glass fiber layer and the glass fiber layer are integrated with the same acrylic binder so that the glass fiber layer partially penetrates into the web layer, the adhesion between the glass fiber layer and the web layer becomes extremely good. In the pasting with the conventional dry GM shown in FIG. 3, there is a space between the web layer and the dry GM, so that the gas generated during the battery charging largely stays in this space,
It was often observed that the utilization of the electrode plate was reduced.
However, in the case of the separator according to the present invention, since a space larger than the binding space between the glass fibers cannot be formed between the web layer and the glass fiber layer, such a problem is solved because minute gas escapes without growing greatly. Became. Further, since the glass fiber layer is embedded in the web layer so as to be integrated, the effect of preventing the glass fiber from falling off is remarkable.

The thickness ratio of the web layer and the glass fiber layer is preferably 1.0 to 1.0 for the former and 1.5 to 3.0 for the latter in order to provide the effect of arranging the amount of the electrolyte solution on the anode side and the elasticity of the glass mat.

The thickness of the separator is suitable for a thin type having a thickness of about 0.8 to 0.7 mm, but it can be applied to a thicker type and is not particularly limited.

As the type of acrylic binder, all acrylic binders can be applied as long as they are excellent in acid resistance and oxidation resistance, but among them, those containing dialkyl sulfosuccinate are more preferable. If the amount of binder attached is large, the electrical resistance will increase due to more clogging between fibers and silica, but by using a mixture of dialkyl sulfosuccinate, the permeability of the electrolyte will increase and the electrical resistance will increase. Reduce resistance.

Although various surfactants can be considered as penetrants, they withstand redox use during storage battery use and do not deteriorate,
It is necessary not to elute harmful substances, and dialkyl sulfosuccinate satisfies these conditions, so it is particularly suitable. The amount of the binder attached is preferably 0.005 to 5% of the weight of the separator, but is preferably 0.05%.
It is in the range of 5 to 2.0%.

The present invention relates to a two-layer co-wet paper sheet of a web layer and a glass fiber layer, which is made of the same acrylic binder as the binder between the materials of the web layer and the fibers of the glass fiber layer. A major feature is that the entire surface of the two-layer sheet is bonded, including integration. In particular, the wet-fabricated glass fiber layer was hard to be embedded in the web to achieve strong integration, and the wettability with the electrolytic solution was improved and the gas release property was also improved. As shown in FIG. 3, a glass fiber layer made of wet-processed short fibers is formed into a strip 2
Just by applying an adhesive to the rows and sticking them to each other, the glass fibers are likely to be peeled off and fall off, and the gas releasing property is also a problem, but in the present invention, these problems are solved and at the same time continuous production is possible. It is now possible to provide an easy and inexpensive separator.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to provide a lead storage battery separator having a glass mat, which is thin, has excellent acid resistance and oxidation resistance, has low electric resistance, excellent heat resistance, and has high productivity.

[Brief description of drawings]

1 is a side view of an embodiment of the present invention, FIG. 2 is a side view of a conventional separator, FIGS. 3 and 4 are front and top views of a conventional separator, and FIG. 5 is a side view showing another embodiment of the present invention. Is. 1 ... Separator, 2 ... Web layer, 3 ... Glass fiber layer

Claims (4)

[Claims] 1. A) 23 to 43% by weight of fibers mainly composed of glass fibers having an average diameter of 0.8 to 3.5 μ, 57 to 77% by weight of silica powder having a specific surface area of 100 m ² / g or more, further the fibers and A web layer with a density of 0.2 to 0.4 g / cm ³ and a mean diameter of 10 ~ 20μ glass fiber and 10 ~ of glass fiber
Wet papermaking with or without adhesion with 20% by weight acrylic binder, two layers of glass fiber layer with average density of 0.17 to 0.25 g / cm ³ were bonded together with the entire surface of the two-layer sheet with acrylic binder. A separator for a storage battery, which has been characterized. 2. The former is the ratio of the thickness of the web layer to that of the glass fiber layer.
The storage battery separator according to claim 1, wherein the latter is 1.5 to 3.0 with respect to 1.0. 3. The storage battery according to any one of claims 1 and 2, wherein a plurality of rows of columnar projections are provided on the surface of the web layer which is not attached to the glass fiber layer. Separator. 4. The acrylic binder adhered to the web layer or both the web layer and the glass fiber layer contains dialkyl sulfosuccinate therein, and the amount of the dialkyl sulfosuccinate attached is 0.00% of the separator weight.
The storage battery separator according to any one of claims 1 to 3, which is 5 to 5%.