JPH0745267A - Separator for alkaline battery - Google Patents

Abstract

PURPOSE:To provide a separator for an alkaline battery having both initial hydrophilic performance and permanent hydrophilic performance which can be practically sufficiently satisfied. CONSTITUTION:In at least partly a polyolefin system fiber surface, alpha-olefin of 2 to 12 carbon atom number and non-conjugate diene represented by a formula (where R<1>, R<2> and R<3> independent of each other show alkyl group of 1 to 8 hydrogen or carbon atom number and n shows 1 to 10 number) are copolymerized. A nonwoven fabric containing a fiber, processing a fiber coated with the obtained unsaturated copolymer by a surface active agent containing no nitrogen atom number, serves as a material, to form an alkaline battery use separator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery separator.

[0002]

2. Description of the Related Art Nonwoven fabrics made of nylon fibers such as nylon 6 and nylon 66 or polyolefin fibers such as polyethylene and polypropylene have been used as separators for alkaline batteries. However, since the nylon fiber separator has excellent hydrophilicity, it exhibits a good affinity for an electrolytic solution and an excellent electrolytic solution holding ability, and enables the production of a high-capacity battery. Due to the poor chemical conversion property, there is a drawback that strength deterioration due to fiber deterioration, self-discharge acceleration due to decomposition products, etc. occur, and battery performance remarkably decreases. On the other hand, the polyolefin fiber separator has no problem in terms of alkali resistance and oxidation resistance at high temperatures,
Since the hydrophobicity is large, the affinity with the electrolytic solution is poor, the electrolyte retaining performance is poor, and it is difficult to obtain a high-capacity battery.

As a solution to such a problem, (i) a polyolefin fiber nonwoven fabric is treated with a water-soluble wetting agent such as a nonionic surfactant to temporarily hydrophilize the nonwoven fabric, followed by electrolysis. Method for increasing affinity with liquid and
(ii) subjecting the polyolefin fiber nonwoven fabric to a treatment using a solvent (for example, polyethylene glycol etc.), a treatment using a sulfuric acid-chromic acid mixture, a sulfonation treatment, an ozone treatment, a corona treatment, a plasma treatment, etc. There has been proposed a method for making hydrophilic (see, for example, JP-A-56-3973). However, in the case of the method (i), the water-soluble treatment agent is eluted into the electrolytic solution over time, which not only causes the disappearance of the re-wetting property of the separator and the increase of the internal resistance of the battery, but also However, depending on the kind of the treating agent, there is a problem that it is decomposed by the redox reaction of the electrode and remarkably deteriorates the battery performance. Further, in the case of the method (ii), the electrolytic solution retention characteristics of the separator during charge and discharge of the battery (force to retain the electrolytic solution), that is, the separation of the electrolytic solution by the oxygen gas generated at the anode during charging from the separator. Or, since little consideration is given to the volume change of the electrode plate due to repeated charging / discharging and absorption of the electrolyte solution into the electrode plate due to porosity, the initial hydrophilicity and permanent hydrophilicity that are fully satisfactory for practical use However, the fact is that it cannot be added to a polyolefin fiber separator.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above problems of the prior art and provides a non-woven separator for an alkaline battery having both an initial hydrophilicity and a permanent hydrophilicity which are sufficiently satisfactory for practical use. It was done for good.

[0005]

That is, according to the present invention, at least a part of the surface of a polyolefin fiber is composed of an α-olefin having 2 to 12 carbon atoms and a general formula (I):

[Chemical 2] (In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n is 1 to 1).
A non-woven fabric containing a fiber obtained by copolymerizing a non-conjugated diene represented by the formula (0) is coated with an unsaturated copolymer, and the fiber is treated with a surfactant containing no nitrogen atom. The present invention relates to an alkaline battery separator used as a material.

The polyolefin fiber which is the base fiber of the alkaline battery separator according to the present invention is not particularly limited, and any polyolefin fiber conventionally used as a base material of a separator may be appropriately used. For example, a fiber produced from a polyolefin-based resin selected from the group consisting of homopolymers of α-olefins having 2 to 8 carbon atoms, copolymers of these α-olefins and terpolymers is appropriately used. Although it may be used, from the viewpoint of processability, economy and affinity with an unsaturated copolymer which will be described in detail below, a propylene-based polymer, for example,
A propylene homopolymer, a propylene-ethylene copolymer, a propylene-ethylene-butene-1-terpolymer and a propylene-4-methyl-pentene-1 copolymer are particularly preferable. Preferred MF of propylene polymer
R (melt flow rate measured according to JIS-K-6758) is 10 to 100 g / 10 minutes, especially 20 to 50
g / 10 minutes.

At least a part of the surface of the polyolefin fiber base material is obtained by copolymerizing an α-olefin having 2 to 12 carbon atoms and a non-conjugated diene represented by the general formula (I). Coated with a saturated copolymer.

Examples of such α-olefins include ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene and 3,3-. Dimethyl-1-butene, 4,
4-dimethyl-1-pentene, 3-methyl-1-hexene, 4-methyl-1-hexene, 4,4-dimethyl-1
-Hexene, 5-methyl-1-hexene, allylcyclopentane, allylcyclohexane, allylbenzene, 3
-Cyclohexyl-1-butene, vinylcyclopropane, vinylcyclohexane, and 2-vinylbicyclo
[2,2,1] -heptane and the like are exemplified. Among these, ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-methyl-1-hexene, etc. Preferred is propylene in particular. These α-olefins may be used alone or in combination of two or more. In particular, when the α-olefin is propylene, it is preferably used in combination with at least one of ethylene, 1-hexene, 1-butene, 4-methyl-1-pentene and 3-methyl-1-butene. When two or more α-olefins are used, the α-olefins may be randomly distributed in the unsaturated copolymer or may be distributed in blocks.

The non-conjugated diene represented by the general formula (I) copolymerized with the above-mentioned α-olefin is 1,4
-Diene (for example, 2-methyl-1,4-pentadiene, 4-methylidene-1-hexene, 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,4-heptadiene, 4-ethyl-1,4-hexadiene, 4,4-dimethyl-1,4
-Hexadiene, 4-methyl-1,4-heptadiene,
4-methyl-1,4-heptadiene, 5-methyl-1,4
-Heptadiene, 5-methyl-1,4-octadiene, etc.), 1,5-dienes (for example, 1,5-heptadiene, 1,5-octadiene, 5-methyl-1,5-heptadiene, 6-methyl) -1,5-heptadiene and 2
-Methyl-1,5-hexadiene etc.), 1,6-dienes
(For example, 1,6-octadiene, 6-methyl-1,6-
Octadiene, 7-methyl-1,6-octadiene, 2
-Methyl-1,6-heptadiene, 6-methylidene-1
-Octene, 6-ethyl-1,6-octadiene, 6,7
-Dimethyl-1,6-octadiene, 1,6-nonadiene, 6-ethyl-1,6-nonadiene, 7-methyl-1,
6-nonadiene, 7-methyl-1,6-decadiene and the like), 1,7-dienes (for example, 1,7-nonadiene,
7-methyl-1,7-nonadiene, 8-methyl-1,7-
Nonadiene, and 2-methyl-1,7-octadiene, etc.), 1,8-dienes (for example, 8-methyl-1,8-decadiene, and 9-methyl-1,8-decadiene, etc.),
1,9-dienes (for example, 1,9-decadiene, and 9-methyl-1,9-decadiene, etc.), 1,10-dienes (for example, 1,10-undecadiene, etc.), 11-diene Examples (eg, 1,11-dodecadiene, etc.), 1,12-dienes (eg, 1,12-tridecadiene, etc.), and 1,13-dienes (eg, 1,13-tetradecadiene, etc.) are exemplified. To be done. Among these specific examples, particularly preferred are 4-methyl-1,4-hexadiene and 5
-Methyl-1,4-hexadiene, 6-methyl-1,6-
Octadiene, 7-methyl-1,6-octadiene, and 1,9-decadiene, among others, 7-methyl-1,6-octadiene, 6-methyl-1,6-octadiene, 1,9
-Decadiene and 1,11-dodecadiene. If desired, two or more of these non-conjugated dienes may be used in combination. For example, 4-methyl-1,4-hexadiene and 5-
Methyl-1,4-hexadiene in a weight ratio of 95: 5 to 5:
You may use together in the ratio of 95. These chain non-conjugated dienes may be randomly distributed in the unsaturated copolymer or may be distributed in blocks.

In the present invention, the unsaturated copolymer used as the coating material for the above-mentioned polyolefin fiber is obtained by converting the above α-olefin and non-conjugated diene into α-olefin by using a Ziegler-Natta catalyst for α-olefin polymerization. It can be produced by copolymerization using a method and an apparatus similar to the production of olefin polymer. Specific examples of such a production method include JP-A Nos. 55-165907, 56-30414, 56-36508 and 57-.
Examples thereof include those described in JP-A-155206 and JP-A-2-145611.

The content of the constituent component derived from the non-conjugated diene in the unsaturated copolymer is usually 0.1 to 15 mol%, preferably 0.5 to 8 mol%, and especially 1 to 6 mol%. And
If it is less than 0.1 mol%, the content of unsaturated groups in the copolymer becomes too small, and the effect on the electrochemical oxidation reaction by oxygen gas generated from the anode (particularly, the electrolyte retaining ability) is If it is not sufficiently exhibited, and if it exceeds 15 mol%, not only the productivity of the unsaturated copolymer is deteriorated, but also due to stickiness of the copolymer, deterioration of crystallinity, etc. It becomes difficult to carry out the coating process due to the formation of fibers.

The molecular weight of the unsaturated copolymer used in the present invention is not particularly limited as long as it has a resin property and a suitable coating property for the polyolefin fiber, and is not particularly limited. When the olefin monomer mainly consists of propylene, JIS-K-6
Melt flow rate (MFR) measured according to 758
Is 0.1 to 500 g / 10 minutes, preferably 1 to 200 g /
10 minutes, especially 10-150 g / 10 minutes, especially 20-20
It has a molecular weight corresponding to 50 g / 10 minutes. In general,
In the case of melt blown nonwoven fabric, MFR is 200 to 50
Unsaturated copolymers of 0 g / 10 min are used, but in the case of staple fibers, unsaturated copolymers with MFR of 10-150 g / 10 min are used. In particular, in the case of a fine denier fiber having a denier of 2 to 3 or less, the MFR is 20 to 50.
Most preferred are unsaturated copolymers of g / 10 minutes.

The melting point (value by DSC method) of the unsaturated copolymer used in the present invention is generally from 100 ° C to 16 ° C.
0 ° C, preferably 110 ° C to 155 ° C, particularly 1
It is 20 ° C to 150 ° C. Further, the crystallinity (value by X-ray analysis method) of the unsaturated copolymer is 10 to 70%, preferably 30 to 55%. Furthermore, the crystalline unsaturated copolymer is a resin that can be extrusion-molded or injection-molded by itself, and its elastic modulus (value according to JIS-K-7203) is 3000 to 30000 kg / cm ² , preferably Is 88
It is from 00 to 22000 kg / cm ² .

The base fiber of the alkaline battery separator according to the present invention is prepared by coating at least a part of the surface of the polyolefin fiber with the above-mentioned unsaturated copolymer. The coverage of the polyolefin fiber is not particularly limited, but is usually 30% or more, preferably 50% or more, and when it is lower than 30%, it is difficult to achieve the intended purpose of the present invention. The coating method of polyolefin fibers is roughly classified into a coating method and a composite spinning method.

The coating method includes, for example, immersing the polyolefin fiber in a resin solution prepared by dissolving or dispersing the above-mentioned unsaturated copolymer in a suitable solvent (eg, xylene, O-dichlorobenzene), or It may be performed by spraying the resin liquid onto the polyolefin fibers. The concentration of the resin liquid is generally 5 to 30% by weight.

As the composite spinning method, a method known in the art, for example, a core-sheath spinning method, a parallel spinning method, a sea-island spinning method, a radial spinning method, a polymer alloy spinning method, or the like may be appropriately adopted. However, the stability of fine denier spinning, the crimpability and stability of fiber crimping, the ease of heat setting, the physical properties of the nonwoven fabric during its manufacture and use (for example, thermal stability, strength, and rigidity). From the standpoints of economic efficiency and the like, a core-sheath spinning method using the above-mentioned polyolefin fiber as a core component and the above-mentioned unsaturated copolymer as a sheath component is particularly preferable.
The cross-sectional form of the spun fiber may be circular, flat, polygonal, or the like.

In the case of a composite fiber having a core-sheath structure, the volume ratio of the unsaturated copolymer as the sheath component is usually 5 to 7.
When it is 0%, preferably 10 to 50%, and less than 5%, the composite spinning becomes extremely difficult and the production efficiency is significantly reduced, and also the fiber surface is damaged during the production of the nonwoven fabric and during the hydrophilization process. If the performance of the final product is deteriorated due to the above, and if it exceeds 70%, the drawability / crimp processability and heat setting property during spinning are deteriorated, and the physical properties of the composite fiber, especially Young's modulus and Thermal stability and the like are reduced.

The content of the above-mentioned polyolefin fiber coated with the unsaturated copolymer in the nonwoven fabric is 30% by weight or more, preferably 50% by weight or more, and when the content is less than 30% by weight. However, the intended purpose of the present invention cannot be sufficiently achieved.

Hydrophilicity is imparted to the coated polyolefin fiber by treating it with a surfactant containing no nitrogen atom. As this type of surfactant, one or more known ones may be appropriately selected and used, and the surfactants are not particularly limited, and the following surfactants are exemplified: (i) sulfone Acid salt ... For example, alkylbenzene sulfonate, sulfosuccinate ester salt, (alkyl) naphthalene sulfonate, and formalin condensate of (alkyl) naphthalene sulfonate, alkane sulfonate,
α-olefin sulfonate, lignin sulfonate,
And petroleum sulfonate etc. (ii) Phosphoric acid ester salt ... For example, alkyl phosphoric acid ester salt, polyoxyalkylene alkyl ether phosphoric acid ester salt, polyoxyalkylene alkyl aryl ether phosphoric acid ester salt, and the like.

(Iii) Carboxylate salt: For example, a salt of a saturated or unsaturated fatty acid having 6 to 20 carbon atoms or a hydroxyl group-containing fatty acid, and the like. (iv) Sulfate ester salt ... For example, alkyl sulfate ester salt, polyoxyalkylene alkyl sulfate ester salt, polyoxyalkylene alkylaryl ether sulfate ester salt, higher fatty acid ester sulfate ester salt,
And sulfated olefins. (v) Polyoxyalkylene nonionic surfactant ...
... For example, polyoxyalkylene alkylaryl ether, polyoxyethylene polyoxypropylene polyol, polyoxyalkylene alkyl ether, polyoxyalkylene polyhydric alcohol fatty acid ester, polyoxyalkylene styrenated aryl ether, and polyoxyalkylene fatty acid ester. (vi) Polyhydric alcohol-based nonionic surfactant ... For example, polyhydric alcohol fatty acid ester and the like.

Particularly suitable surfactants are sulfonic acid salts, phosphoric acid ester salts, and alkyl ether type, alkyl allyl ether type or pluronic type polyethylene glycol nonionic surfactants. In addition, HLB of the nonionic surfactant is preferably 12 to 15 from the viewpoint of the wettability of the surfactant with respect to the polyolefin fibers and the rewettability of the electrolytic solution with respect to the separator.

It should be noted that surfactants containing nitrogen atoms, such as amine salt type cationic surfactants, quaternary ammonium salt type cationic surfactants, amino acid type amphoteric surfactants and betaine type amphoteric surfactants, are It is disadvantageous because it produces residues containing nitrogen atoms that are decomposed by hydrolysis or oxidation reactions and increase the self-discharge of the battery.

The hydrophilic treatment of the polyolefin fiber (including the unsaturated copolymer fiber) with the above-mentioned surfactant containing no nitrogen atom may be carried out in a state of being processed into a web or a state of being processed into a non-woven fabric. . The amount of the surfactant adhering to the polyolefin fiber is not particularly limited, but is generally 0.1 to 3% by weight, preferably 0.1.
3 to 1.5% by weight is sufficient, and when it is less than 0.1% by weight, it is not possible to impart sufficient initial hydrophilicity to the polyolefin fiber, and when it is more than 3% by weight. In addition to increasing the elution amount of the surfactant into the electrolytic solution and causing a decrease in battery performance, when the surfactant treatment is performed before processing into the nonwoven fabric, the fiber surface may be sticky. The productivity of the nonwoven fabric is significantly reduced.

The method for producing the non-woven fabric made of the coated polyolefin fiber subjected to the above-mentioned hydrophilization treatment is not particularly limited, and a method known per se, for example, the thermal bond method [thermal calendar method (gravure method Roll type, smooth roll type, etc.), hot air through method, ultrasonic heating method, etc.], chemical bond method, needle punch method, etc. Further, the web form is not particularly limited, but examples thereof include a random web, a parallel web, a cross web, and a criss cross web. However, alkaline battery separator performance, for example, the absorption rate and retention rate of the electrolyte,
From the viewpoint of mechanical strength and stability, the hot air through method and the smooth roll type thermal calender method are preferably used in combination as the manufacturing method, and the web form is preferably cross web or criss cross web.

The present invention will be described below with reference to examples. Example 1 Random copolymer of propylene (96.7 mol%) and 7-methyl-1,6-octadiene (3.3 mol%) (MFR:
30 g / 10 min, elastic modulus: 14500 kg / cm ² ) as a sheath component, and a propylene homopolymer (MFR: 30 g / 10 min) as a core component, a core-sheath type composite fiber (core / sheath volume ratio: 70/30 ,
Young's modulus: 140 kg / mm ² , strength: 4.0 g / d, fineness: 1.5
Denier, length: 51 mm) 80% by weight, and a core-sheath type composite containing ethylene homopolymer (MFR: 30 g / 10 min) as a sheath component and propylene homopolymer (MFR: 30 g / 10 min) as a core component. Adhesive fiber (core / sheath volume ratio: 50/50, fineness:
A web in which 20 wt% of 1.5 denier, length: 51 mm) was uniformly mixed was heated at 140 ° C. for 30 seconds without pressing (hot air through method), and immediately after that, 110
A non-woven fabric (unit weight: 77 g / m ² , thickness: 0.20 mm) was prepared by calendering at 40 ° C / 40 kg / cm ² . By subjecting the non-woven fabric to an impregnation treatment using a 5% aqueous solution of sodium dodecylbenzene sulfonate (“Silkerol CAP” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the separator 1 for alkaline batteries according to the present invention (adhesion of sodium dodecylbenzene sulfonate) Amount: 0.4% by weight, basis weight: 77 g /
m ² , thickness: 0.20 mm) was obtained.

Example 2 Random copolymer of propylene (96.7 mol%) and 7-methyl-1,6-octadiene (3.3 mol%) (MFR:
30 g / 10 min, elastic modulus: 14500 kg / cm ² ) as a sheath component, and a propylene homopolymer (MFR: 30 g / 10 min) as a core component, a core-sheath type composite fiber (core / sheath volume ratio: 90/10 ,
Young's modulus: 160 kg / mm ² , strength: 4.2 g / d, fineness: 1.5
70% by weight of denier, length: 51 mm), and a core-sheath composite having ethylene homopolymer (MFR: 30 g / 10 min) as a sheath component and propylene homopolymer (MFR: 30 g / 10 min) as a core component. Adhesive fiber (core / sheath volume ratio: 50/50, fineness:
1.5 denier, length: 51 mm) 30% by weight of a uniformly mixed web was heated at 140 ° C for 30 seconds without pressing (hot air through method), and then immediately at 110 ° C.
A non-woven fabric (unit weight: 75 g / m ² , thickness: 0.20 mm) was prepared by calendering under a condition of 40 kg / cm ² . The non-woven fabric is a polycyclic aliphatic alkyl phosphate K
The alkaline battery separator 2 according to the present invention (adhesion amount of the K salt: 0.5 is applied by impregnation with a 5% aqueous solution of salt (“DPC-23” manufactured by Sanyo Kasei Co., Ltd.).
% By weight, basis weight: 75 g / m ² , thickness: 0.20 mm).

Example 3 Propylene (95.5 mol%) and non-conjugated diene (4-methyl-1,4-hexadiene 80 mol% and 5-methyl-1,4)
-Mixture with 20 mol% hexadiene)) (4.5 mol%)
A core-sheath composite that uses a random terpolymer (MFR: 35 g / 10 min, elastic modulus: 12600 kg / cm ² ) as a sheath component and a propylene homopolymer (MFR: 30 g / 10 min) as a core component. Fiber (core / sheath volume ratio: 70/30, Young's modulus: 140k
g / mm ² , strength: 4.0 g / d, fineness: 1.0 denier, length:
70 mm) 60% by weight, and ethylene homopolymer (MF
R: 30 g / 10 min) as a sheath component and a propylene homopolymer (MFR: 30 g / 10 min) as a core component, a core-sheath type composite adhesive fiber (core / sheath volume ratio: 50/50, fineness: 1. 40 wt% of 5 denier, length: 51 mm) was mixed uniformly. The mixture was mixed with polyoxyethylene nonylphenol ether (“Emulgen PI-20T” manufactured by Kao Corporation, HLB: 13.
After the impregnation treatment with the 5% aqueous solution of 2) (adhesion amount of the surfactant: 0.7% by weight), a web was prepared, and the web was pressed without pressing (hot air through method), 14
After heating at 0 ℃ for 30 seconds, immediately at 110 ℃, 40kg /
By applying a calendar under the condition of cm ^2, the separator 3 for alkaline batteries according to the present invention (Basis weight: 75 g / m 2
² , thickness: 0.20 mm) was obtained.

Comparative Example 1 A separator 1'for an alkaline battery (unit weight: 75 g / m ² , thickness: 0.20 mm) was obtained in the same manner as in Example 1 except that the impregnation treatment using a surfactant was not carried out. It was

Comparative Example 2 Nylon 66 fiber (fineness: 1.5 denier, length: 38 mm)
70% by weight, and a core-sheath type composite fiber having nylon 6 as a sheath component and nylon 66 as a core component (core / sheath volume ratio: 50
/ 50, fineness: 2.0 denier, length: 50 mm) 30% by weight
The web prepared by uniformly mixing the
(Hot air through method), after heating at 230 ℃ for 30 seconds, immediately put on a calendar at 130 ℃ under the condition of 30 kg / cm ² for alkaline battery separator 2 ′ (unit weight: 75 g / m ² , thickness: 0. 20 mm) was obtained.

Comparative Example 3 A core-sheath type composite adhesive fiber (core / sheath) containing ethylene homopolymer (MFR: 30 g / 10 min) as a sheath component and propylene homopolymer (MFR: 30 g / 10 min) as a core component. Volume ratio: 50/5
0, fiber: 1.5 denier, length: 51 mm) 30% by weight, and fiber consisting of propylene homopolymer (MFR: 30 g / 10 min) (fineness: 1.5 denier, length: 51 mm) 70% by weight After heating the uniformly mixed web under no pressure (hot air through method) at 140 ° C for 30 seconds, it is immediately calendered at 110 ° C under the condition of 40 kg / cm ² to separate the alkaline battery separator 3 '( :
75 g / m ² , thickness: 0.20 mm) was obtained.

Alkaline battery separators 1, 2, 3,
Characteristics of 1 ', 2'and 3' The lower end of a sample with a liquid absorption rate of 2.5 cm x 18 cm is hydrated with KOH 30%
It is immersed in (20 ° C.) up to 5 mm, and the height (mm) of the aqueous solution raised for 30 minutes is measured (Bayrec method). 2. Retention rate 10 cm × 10 cm sample weight (W), and KO the sample
A 30% H30 aqueous solution (20 ° C.) was dipped for 1 hour in a state where the aqueous solution was sufficiently absorbed, and then hung up for 10 minutes, and then the weight (W ′) of the sample was measured to measure the liquid retention rate [( W '
−W) × 100 / W] is calculated. 3. Oxidation resistance A sample is immersed in a mixed solution of 250 ml of a 5% aqueous solution of KMnO ₄ and 50 ml of a 30% aqueous solution of KOH (50 ° C.) for 1 hour to determine the weight loss rate (%) of the sample. 4. Alkali resistance Dipping the sample in KOH 30% aqueous solution (80 ° C) for 7 days,
The weight reduction rate (%) of the sample is determined. The above measurement results are shown in Table 1 below.

[0032]

[Table 1]

As is clear from Table 1, all of the separators 1 to 3 according to the present invention are excellent in liquid absorption rate, liquid retention rate, oxidation resistance, and alkali resistance, and are suitable as separators for alkaline batteries. Is. On the contrary,
Since the separators 1'and 3'have large hydrophobicity, they have poor liquid absorption rate and liquid retention rate, and are not suitable as separators for alkaline batteries for cycling, which are used by repeating charging and discharging. Further, the separator 2'has very poor oxidation resistance and alkali resistance and cannot be used under severe conditions such as high temperature.

Regarding the separators 1 to 3 and 3 ', the electrolyte retention rate (%) and the strength (kg / 2.
The change is shown in Table 2 below. The electrolytic solution retention rate in this case was determined by immersing a sample subjected to oxidation treatment in accordance with the test method described above in a state where a 30% KOH aqueous solution was sufficiently absorbed, and then immersing the sample in the aqueous solution for 1 hour. It is the value of the liquid retention rate relative to the weight of the sample after the sample was placed in a centrifuge for 10 minutes under the condition of 50G.

[0035]

[Table 2] As is clear from Table 2, the separator 1 according to the present invention
It can be seen that all of No. 3 to No. 3 do not show a decrease in dissolution or strength even in a high oxidation state, and that the ability to hold the electrolytic solution is improved by being oxidized.

[0036]

EFFECT OF THE INVENTION The separator according to the present invention has an initial hydrophilic property required for the production of an alkaline battery (for example, the absorption rate and the retention rate of the electrolytic solution) and a permanent hydrophilic property required when the alkaline battery is charged and discharged and stored. Since it also has performance (for example, electrolyte retaining power), it is suitable as a separator for alkaline batteries. In this case, the initial hydrophilic performance is due to the treatment of the surfactant containing no nitrogen atom, and the permanent hydrophilic performance is due to the coating with the unsaturated copolymer.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location D04H 1/42 X 7199-3B D06M 15/21 (72) Inventor Akashi Shigetoshi Toho-cho, Yokkaichi-shi, Mie No. 1 Mitsubishi Petrochemical Co., Ltd. In Yokkaichi Research Institute (72) Inventor Shuji Moriya 1138-1 Shimosho, Kurashiki-shi, Okayama Prefecture Kurashiki Textile Processing Co., Ltd. Research and Development Department (72) Toshiya Tokuhiro 1138 1Shimosho, Kurashiki-shi, Okayama Prefecture Kurashiki Textile Processing Co., Ltd.

Claims (4)

[Claims] 1. At least a part of the surface of a polyolefin-based fiber and an α-olefin having 2 to 12 carbon atoms and a general formula (I): (In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and n is 1 to 1).
A non-woven fabric containing a fiber obtained by copolymerizing a non-conjugated diene represented by the formula (0) is coated with an unsaturated copolymer, and the fiber is treated with a surfactant containing no nitrogen atom. The alkaline battery separator used as the material. 2. The alkaline battery separator according to claim 1, wherein the surfactant treatment containing no nitrogen atom is performed in a fiber state, a web state or a non-woven fabric state. 3. The separator for an alkaline battery according to claim 1, which is a non-woven fabric containing a core-sheath composite fiber having a polyolefin fiber as a core component and an unsaturated copolymer as a sheath component. 4. The separator for an alkaline battery according to claim 1, wherein the nonwoven fabric contains at least 30% by weight of a polyolefin fiber whose surface is coated with an unsaturated copolymer.