Alkaline battery separator
An alkaline battery separator having alkali-resistant fibers, beaten cellulose fibers and a binder, wherein an overall freeness, in terms of CSF, is at least 700 ml and at most 765 ml; weight ratios of the alkali-resistant fibers and the beaten cellulose fibers are 28:72 to 72:28; the beaten cellulose fibers comprise mercerized natural wood fibers having a freeness, in terms of CSF, of at least 150 ml and less than 550 ml; and at least a portion of the alkali-resistant fibers is polyvinyl alcohol-based fibers.
1. An alkaline battery separator, comprising alkali-resistant fibers, beaten cellulose fibers and a binder, wherein:
1) an overall freeness, in terms of CSF, is at least 700 ml and at most 765 ml;
2) weight ratios of the alkali-resistant fibers and the beaten cellulose fibers are 28:72 to 72:28;
3) the beaten cellulose fibers comprise mercerized natural wood fibers having a freeness, in terms of CSF, of at least 150 ml and less than 550 ml; and
4) at least a portion of the alkali-resistant fibers is polyvinyl alcohol-based fibers.
2. The alkaline battery separator according to claim 1 , wherein said polyvinyl alcohol-based fibers have an in-water dissolution temperature of at least 90° C.
3. The alkaline battery separator according to claim 1 wherein the binder is a polyvinyl alcohol-based binder.
4. The alkaline battery separator according to claim 1 , wherein weight ratios of the alkali-resistant fibers, the beaten cellulose fibers, and the binder are 25 to 60:25 to 60:5 to 20.
5. The alkaline battery separator according to claim 1 , wherein a freeness of the mercerized natural wood fibers is, in terms of CSF, at least 150 ml and less than 450 ml.
6. The alkaline battery separator according to claim 1 , wherein a content of a fibrillated substance of organic solvent-spun cellulose fibers is 10% by weight or less based on the total weight of the alkaline battery separator.
7. The alkaline battery separator according to claim 1 , further comprising regenerated cellulose fibers, wherein a content of the regenerated cellulose fibers is 25% by weight or less based on a total weight of the separator.
8. The alkaline battery separator according to claim 1 , wherein a fineness of the alkali-resistant fibers is 0.1 to 0.8 dtex.
9. The alkaline battery separator according to claim 1 , wherein air permeability of the alkaline battery separator is 13 cc/cm2/sec or lower.
10. The alkaline battery separator according to claim 1 , wherein a degree of swelling of the alkaline battery separator in a 35%-KOH water solution at 25° C. is 41% or lower.
11. The alkaline battery separator according to claim 1 , wherein an alkali elution amount of the alkaline battery separator in a 35%-KOH water solution at 60° C. is 3% or lower.
12. The alkaline battery separator according to claim 1 , wherein:
a weight per unit area of the alkaline battery separator is 20 to 50 g/m 2 ; and
a thickness of the alkaline battery separator is 70 to 150 μm.
13. An alkaline battery, comprising the alkaline battery separator according to claim 1 .
14. The alkaline battery separator according to claim 1 , wherein said polyvinyl alcohol-based fibers have an in-water dissolution temperature ranging from 90° C. to 200° C.
15. The alkaline battery separator according to claim 1 , wherein said polyvinyl alcohol-based fibers have an in-water dissolution temperature ranging from 100° C. to 150° C.
16. The alkaline battery separator according to claim 1 , wherein said polyvinyl alcohol-based fibers comprise a vinyl alcohol-based polymer which has an average polymerization degree of 1,000 to 5,000 and a saponification degree of 95% by mol or higher.
17. The alkaline battery separator according to claim 1 , wherein said polyvinyl alcohol-based fibers comprise a vinyl alcohol-based polymer copolymerized with a distinct copolymer component wherein the copolymerization amount does not exceed 20% by mol.
18. The alkaline battery separator according to claim 1 , wherein said polyvinyl alcohol-based fibers are acetalized.