JPH01175165A - Separator for alkaline cell - Google Patents

Abstract

PURPOSE:To form a cell with a long life for high-efficiency discharge by constituting a separator for alkaline cell with the specific constituent and method and forming the separator with excellent oxidation resistance and alkali resistance. CONSTITUTION:A separator is formed with hollow 6 nylon fibers 1 and thermo- adhesive fibers 2 added with polyamide deterioration preventing agent 0.2-3wt.%, e.g., 1wt.%, in advance. The fibers 1 have a hollow cross section, the size of 1.5de, and the fiber length of 38mm, and 70wt.% of them is mixed. The fibers 2 use copolymer nylon as the sheath constituent and 6 nylon as the core constituent and have the size of 2de and the fiber length of 51mm, and 30wt.% of them is mixed. After a cross web is formed, it is calender- processed and heated and pressed, and the fibers 1 and fibers 2 are stuck together by the deposition of the fibers 2. The separator obtained by the above method has excellent absorbing property and retaining property of an electrolyte and excellent alkali resistance and oxidation resistance, thereby a cell with a long life for high-efficiency discharge can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alkaline battery separator made of a polyamide 114 male'+p nonwoven fabric containing polyamide fibers with a hollow cross section.

[Conventional technology and its problems]

Conventionally, separators for alkaline batteries were made of nylon 6,
Nonwoven fabrics made of polyamide fibers such as nylon 66 or polyolefin fibers such as polypropylene are used.

Nonwoven fabrics made of polyamide fibers have good electrolyte absorption and retention properties, and have a large discharge capacity, so they have the advantage of being usable for high-rate applications.
Due to its poor oxidation resistance, it is used as a separator for alkaline batteries.
When using C, there is a major drawback that the life span is shortened due to deterioration and decomposition of the fibers.9.

On the other hand, separators made of nonwoven polyolefin fibers have excellent alkali resistance and oxidation resistance, and can be expected to have a long service life. Although it can be used for current applications, it has the disadvantage that it cannot be used for applications that involve high-rate discharge in a short period of time due to the occurrence of a leak phenomenon.

In addition, adding surfactants to polyolefin fibers with excellent alkali resistance, applying fine fibers, +I1. Efforts have been made to improve the retention of the electrolyte by improving the fiber surface morphology, but because it is fundamentally hydrophobic, the effect is only temporary and cannot be applied to high-rate discharge applications. is the current situation.

[Means for solving problems]

The present invention was made as a result of intensive research and study in order to solve the problems of the above-mentioned conventional technology.The present invention has been made as a result of intensive research and consideration in order to solve the problems of the above-mentioned conventional technology. By constructing an adhesive iR fiber sheet using fibers with a hollow cross section that has been treated with anti-oxidation treatment, it is resistant to alkali without reducing the initial fiber strength.

The present invention provides a polyamide-based separator for alkaline batteries that has excellent oxidation resistance and MS liquid retention properties.

That is, amine-based fibers are generally used as anti-degradation agents for rubber, glass, etc. in order to improve the acid-alkali resistance of polyamide fibers.

So-called anti-aging agents and antioxidants such as phenolics,
They can be used alone or in combination, and can be obtained by applying them by mixing and kneading them before fiber spinning, or applying them by post-processing by pressurizing and heating after spinning.

In the case of applying mixed wires before fiber spinning, if the blending ratio exceeds 3:im percent, the initial strength of the fiber will decrease, which is undesirable, and if it is less than 0.2 weight percent, the alkali resistance will be little improved.

Next, when dyeing is applied by post-processing after spinning, the acid-alkali resistance performance is greatly improved because dyeing is concentrated near the fiber surface that comes into direct contact with the strong alkaline solution, which may prevent such thinking. The initial strength decrease due to the addition of the agent is also small.

Furthermore, by using fibers having a hollow cross-sectional shape as the separator and constituent material, the absorbency and retention of the electrolytic solution are improved due to capillary action, making it particularly preferable. It was also found that the phenomenon of water absorption due to capillary action of electrolyte into the hollow part of the fibers is small unless special pressure is applied, and the more fiber ends there are, the greater the liquid absorption and retention performance becomes.

The separator used in the present invention is a known dry method.

A web formed by a wet method or the like may be used, and is not particularly limited.

Hollow cross section, thickness 8 denier or less, fiber length 51 r
The polyamide fibers of RM or less are preferably 2 deniers or less and 881 or less, and the fibers that have been subjected to the above-mentioned conceptual treatment are 80 weight soft X-cents or more of the entire web, preferably 50 weight percent/7/ It is necessary to include at least When the fiber thickness is 8 denier and the fiber length is 51 f1 or more, the nonwoven fabric becomes coarsely clogged, and the electrolyte retention property as a separator becomes insufficient. It goes without saying that polyamide fibers having other cross-sectional shapes, which have been subjected to anti-conversion treatment as necessary, may also be included.

For bonding between the fibers constituting the web, an engineered resin such as a thermoplastic resin may be used as a binder, but since it will block the ends of the hollow fibers and reduce the liquid absorption performance, polyamide resin with thermal adhesive properties may be used. It is preferable to mix adhesive fibers and heat-treat the mixture. In addition, the heat-adhesive polyamide fiber also
By similarly performing anti-aging treatment after spinning, it is possible to improve acid-alkali resistance without causing a decrease in adhesive performance and strength.

As described above, the separator of the present invention is made of polyamide fibers subjected to anti-aging treatment, and has hollow cross-sections of fibers of 3 denier or less and fiber length of 111 M1 or less, of 30 weight 1% or more. Therefore, compared to conventional nonwoven fabric separators made of polyamide fibers, a polyamide-based alkaline battery separator is obtained which has excellent acid-alkali resistance at high temperatures and also has improved electrolyte absorption and retention properties. It is something that can be done.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples.

〔Example〕

As shown in the drawing, a hollow 6 of L5d x 88fl to which 1% by weight of allylamine deterioration inhibitor has been applied in advance.
2dX5 with 70% by weight of nylon fiber (1) and copolymerized nylon with a melting point of 140°C treated with the same anti-degradation agent as the sheath component and nylon 6 as the core component.
1fl thermal adhesive fiber f! + 80% by weight and mixed with 15511/
,? After forming the cross web of the calendar roll 1
A separator with a thickness of α21 m1 was obtained by calendering and heating and pressurizing at 85° C. and a linear pressure of 25 cycles, and the fibers were integrally bonded together by welding the thermal bonding fibers.

Comparative example 1 6 nylon/ff1 of LlldX47m with normal cross section
ff170. ! The same conditions except that a 5f/ar cross web was formed using 80 weight i4 percent of 2dX5 lH heat-adhesive fibers with copolymerized nylon having a melting point of 140°C as the sheath component and 6 nylon as the core component. was calendered to obtain a seven-layer plate.

Comparative Example 8 A cross web with 659 lengths was formed from 40 weight percent of polypropylene fiber L5dX51fl thermo-liquid layered conjugate fibers with polypropylene fibers L5dX88460% by weight, a sheath component being polyethylene, and a core component being polypropylene.
After heat treatment for 2 minutes using a hot air treatment device at 80℃, the temperature
lθ℃.

Calender treatment was performed under the condition of a linear pressure of 25 wheels to obtain a regular separator having a thickness of α21.

The physical properties of Examples and Comparative Examples 1.2 when used in battery separators are shown below.

*Measurement using a micrometer*2: After immersing in an 80-inch KOH solution for 20 minutes and draining for 10 minutes, the liquid retention weight is based on the weight of the sample.3: After injecting ozone at o, 5, and 8, Tensile strength retention after 100 hours of immersion treatment in KOH solution.

As is clear from the above physical property table, the alkaline battery separator of the example according to the present invention has excellent electrolyte retention properties,
The alkali resistance and oxidation resistance, which were drawbacks of conventional polyamide fibers, are also superior to polypropylene fibers.

〔Effect of the invention〕

Since the present invention has the above structure, the alkaline battery separator has excellent electrolyte absorption and retention properties, as well as alkali resistance and oxidation resistance, thus forming a battery with a long life for high rate discharge. This invention has excellent effects such as:

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view of a separator for alkaline batteries showing one embodiment of the present invention.

Claims (2)

[Claims] (1) Fiber length 5 with hollow cross section, thickness 3 denier or less
1. A separator for an alkaline battery, comprising an adhesive fiber sheet formed from a mixed fiber web containing polyamide fibers having a diameter of 1 mm or less and polyamide fibers containing 30% by weight or more. (2) The separator for alkaline batteries according to claim 1, which uses polyamide fibers to which 0.2 to 3 weight percent of aging prevention treatment agent has been applied.