Method for manufacturing separator web, method for manufacturing separator, separator web, and apparatus for manufacturing separator web

1. A separator original sheet producing method, comprising the steps of:

forming a porous separator original sheet for a battery;

detecting a defect in the separator original sheet; and

forming a defect code including information on a first position of the defect which first position is a position in a width direction of the separator original sheet, the defect code being formed at a portion of the separator original sheet which portion corresponds to a second position of the defect which second position is a position in a longitudinal direction of the separator original sheet, so that the portion at which the defect code is formed indicates the second position of the defect,

wherein the separator original sheet includes a base material and a heat-resistant layer laminated on the base material,

wherein the defect includes at least one of a base material defect present in the base material and a heat-resistant layer defect present in the heat-resistant layer, and wherein the defect code includes information for distinguishing between the base material defect and the heat-resistant layer defect.

2. A separator producing method, comprising the steps of:

(a) forming a separator original sheet for a battery, the separator original sheet being porous;

(b) detecting a defect in the separator original sheet;

(c) forming a defect code including information on a first position of the defect which first position is a position in a width direction of the separator original sheet, the defect code being formed at a portion of the separator original sheet which portion corresponds to a second position of the defect which second position is a position in a longitudinal direction of the separator original sheet, so that a portion at which the defect code is formed indicates the second position of the defect;

(d) cutting the separator original sheet having the defect, of which the information has been recorded in the step (c), in a longitudinal direction of the separator original sheet into a plurality of separators;

(e) reading the information; and

(f) on a basis of the information read in the step (e), identifying at least one of a plurality of separators and providing the at least one of the plurality of separators with a mark for specifying the first position of the defect, the mark being provided at a position of the at least one of the plurality of separators which corresponds to the defect.

3. The separator producing method according to claim 2 , further comprising the steps of:

(g) winding up the at least one of the plurality of separators, which at least one of the plurality of separators has been provided with the mark;

(h) sensing the mark while carrying out an operation of winding off the at least one of the plurality of separators, which has been wound up in the step (g), and winding up the at least one of the plurality of separators again; and

(i) in accordance with the sensing of the mark, stopping the operation and removing the defect.

4. The separator producing method according to claim 3 ,

wherein

in the step (i): the at least one of the plurality of separators is cut in the width direction at two positions opposite to each other in the longitudinal direction with the defect therebetween; the defect is removed; and cut parts of the separator are then connected.

5. The separator producing method according to claim 2 ,

wherein in the step (c), the defect code is recorded at a widthwise end of the separator original sheet.

6. The separator producing method according to claim 2 ,

wherein the step (f) is carried out by attaching a label.

7. A porous separator original sheet for a battery, comprising, a defect code including information on a first position of a defect in the separator original sheet which first position is a position in a width direction, the defect code being formed at a portion of a widthwise end of the separator original sheet which portion corresponds to a second position of the defect which second position is a position in a longitudinal direction, so that the portion at which the defect code is formed indicates the second position of the defect,

wherein the separator original sheet includes a base material and a heat-resistant layer laminated on the base material,

wherein the defect includes at least one of a base material defect present in the base material and a heat-resistant layer defect present in the heat-resistant layer, and wherein the defect code includes information for distinguishing between the base material defect and the heat-resistant layer defect.

8. A separator original sheet producing apparatus, comprising:

a forming section configured to form a porous separator original sheet for a battery;

a defect detecting section configured to detect a defect in the separator original sheet; and

a defect information recording section configured to form a defect code including information on a position of the defect which position is a position in a width direction of the separator original sheet, the defect code being formed at a portion of the separator original sheet which portion corresponds to a second position of the defect which second position is a position in a longitudinal direction of the separator original sheet, so that the portion at which the defect code is formed indicates the second position of the defect,

wherein the separator original sheet includes a base material and a heat-resistant layer laminated on the base material,

wherein the defect includes at least one of a base material defect present in the base material and a heat-resistant layer defect present in the heat-resistant layer, and wherein the defect code includes information for distinguishing between the base material defect and the heat-resistant layer defect.