Film production method

Patent metadata

Field	Value
Publication number	US-11239529-B2
Application number	US-201916599167-A
Country	US
Kind code	B2
Filing date	Oct 11, 2019
Priority date	Sep 30, 2015
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

A desired drying capability is achieved while damage to a film is prevented. A film production method is arranged such that: a production process including a drying step is operated by setting a drying condition, under which to carry out the drying step, for each of at least two periods, the two periods being a first period and a second period later than the first period; the drying condition is changed in at least a part of the first period so as to be enhanced with time; and the drying condition is maintained in the second period so as to be substantially fixed.

First claim

The invention claimed is:

1. A film production method comprising a film drying step, wherein:
the drying step comprises setting a drying temperature of a heating medium at which to carry out the drying step, for each of at least two periods, a first period and a second period later than the first period;
a set value of the drying temperature is changed in at least a part of the first period so as to be increased with time; and
the set value is maintained in the second period so as to be substantially fixed; and
an actual drying temperature of the film is consequently constant throughout the first period and the second period.

2. The film production method as set forth in claim 1 , wherein a decline in actual drying temperature of the film demonstrated in the drying step, the decline being caused by absorption of heat during the drying of the film, is prevented by changing the set value in the first period so that the set value is increased.

3. The film production method as set forth in claim 2 , wherein:
the actual drying temperature of the film is maintained constant in the first period by changing the set value in the first period so that the set value is increased;
the actual drying temperature of the film is maintained constant in the second period by causing the absorption of heat and application of heat to the drying step to reach equilibrium at an end of the first period; and
the actual drying temperature of the film is consequently constant throughout the first period and the second period.

4. The film production method as set forth in claim 1 , wherein a time at which the first period starts is set so that a lead part of the film which is to be formed into a product starts to be subjected to the drying step at the time.

5. The film production method as set forth in claim 1 , wherein:
the drying is carried out by bringing the film into contact with a roller that is heated; and
the set value is a set value of a heating medium to be poured into the roller.

6. The film production method as set forth in claim 1 , wherein an operation of the production process includes a restart of the production process which is stopped.

7. The film production method as set forth in claim 1 , wherein the film is a battery separator.

8. The film production method as set forth in claim 1 , wherein in the drying step, deformation in the film is prevented by carrying out a heat treatment so as to cause shrinkage not only in a functional layer of the film but also in a base material of the film.

Assignees

• Sumitomo Chemical Co

Inventors

• Shin Akihiko
• Takaoka Yuji
• Nakazawa Atsushi
• Sasaki Hideyuki

Classifications

• B32B27/14 Primary

  next to a particulate layer · CPC title

• H01M50/423

  Polyamide resins · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M50/403 Primary

  Manufacturing processes of separators, membranes or diaphragms · CPC title