Fluororesin film having excellent transparency

Patent metadata

Field	Value
Publication number	US-9822225-B2
Application number	US-201314431538-A
Country	US
Kind code	B2
Filing date	Dec 18, 2013
Priority date	Dec 25, 2012
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

The present invention aims to provide an ETFE film having excellent transparency and heat resistance and cost efficiency. The present invention relates to a film including a copolymer containing an ethylene unit, a tetrafluoroethylene unit, and a (fluoroalkyl)ethylene unit represented by Formula (1):

CH 2 ═CX—Rf  (1)

wherein X represents H or F, and Rf represents a fluoroalkyl group having 2 or more carbon atoms, the copolymer containing the (fluoroalkyl)ethylene unit in an amount of 0.8 to 2.5 mol % relative to the amount of all the monomer units and containing the ethylene unit and the tetrafluoroethylene unit at a molar ratio of 30.0/70.0 to 50.0/50.0, the film having a crystallinity of 68% or less, the crystallinity being calculated on the basis of a diffraction intensity curve of the film resulting from X-ray diffraction measurement.

First claim

The invention claimed is:

1. A film comprising a copolymer, the copolymer containing an ethylene unit, a tetrafluoroethylene unit, and a (fluoroalkyl)ethylene unit represented by Formula (1):
CH 2 ═CX—Rf  (1)

wherein X represents H or F, and Rf represents a fluoroalkyl group having 2 or more carbon atoms,
the copolymer containing the (fluoroalkyl)ethylene unit in an amount of 0.8 to 2.5 mol % relative to the amount of all the monomer units and containing the ethylene unit and the tetrafluoroethylene unit at a molar ratio of 30.0/70.0 to 50.0/50.0,
the film having a crystallinity of 68% or less, the crystallinity being calculated by the following equation on the basis of a diffraction intensity curve of the film resulting from X-ray diffraction measurement:
Crystallinity (%)=( S 19 +S 20 )/( S 17 +S 19 +S 20 )×100

wherein S 20 represents a peak area around 2θ=20°,
S 17 represents a peak area around 2θ=17°, and
S 19 represents a peak area around 2θ=19°.

2. The film according to claim 1 ,
wherein a peak area ratio around 2θ=20° calculated by the following equation is 10.0% or less:
Peak area ratio (%)= S 20 /( S 19 +S 20 )×100.

3. The film according to claim 1 ,
wherein a half-width of the peak around 2θ=19° is 3.0 or less.

4. The film according to claim 1 ,
wherein the copolymer has a melt flow rate of 40 (g/10 min) or less at 297° C.

5. The film according to claim 1 ,
wherein transmittance of light having a wavelength of 300 to 1100 nm is 75% or more.

6. The film according to claim 1 ,
wherein an arithmetic average inclination is 0.2° or less.

7. A solar battery including the film according to claim 1 .

8. A method for producing a film comprising a copolymer, the copolymer containing an ethylene unit, a tetrafluoroethylene unit, and a (fluoroalkyl)ethylene unit represented by Formula (1):
CH 2 ═CX—Rf  (1)

wherein X represents H or F, and Rf represents a fluoroalkyl group having 2 or more carbon atoms,
the copolymer containing the (fluoroalkyl)ethylene unit in an amount of 0.8 to 2.5 mol % relative to the amount of all the monomer units and containing the ethylene unit and the tetrafluoroethylene unit at a molar ratio of 30.0/70.0 to 50.0/50.0,
the film having a crystallinity of 68% or less, the crystallinity being calculated by the following equation on the basis of a diffraction intensity curve of the film resulting from X-ray diffraction measurement:
Crystallinity (%)=( S 19 +S 20 )/( S 17 +S 19 +S 20 )×100

wherein S 20 represents a peak area around 2θ=20°,
S 17 represents a peak area around 2θ=17°, and
S 19 represents a peak area around 2θ=19°,
the method comprising the steps of
melting the copolymer by heating to a melting point or higher,
molding the molten copolymer into a film,
rapidly cooling the film by contacting the film maintained at a temperature not lower than the crystallization temperature of the copolymer, with a cooling roll set to a temperature not exceeding a temperature that is higher than the glass transition temperature of the film by 10° C., and
collecting the rapidly cooled film.

9. The method according to claim 8 ,
wherein, a method of contacting the film with the cooling roll is a method of charging the cooling roll with static electricity for firm contact of the film with the cooling roll or a method of using a pressing roll to press the film to the cooling roll for firm contact of the film with the cooling roll.

10. The method according to claim 8 ,
wherein the melting and the molding are performed using an extruder equipped with a die, the die having an outlet set at a distance of 50 mm or less from a contact point of the film with the cooling roll.

Assignees

• Daikin Ind Ltd

Inventors

• Kouketsu Yasuko
• Fukagawa Ryouichi
• Higuchi Tatsuya
• Shimono Takeshi
• Sekiguchi Takashi

Classifications

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• B29L2007/00

  Flat articles, e.g. films or sheets (B29L2024/00 takes precedence) · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title

• B29K2027/12

  containing fluorine · CPC title

• B29C48/142

  using force fields, e.g. gravity or electrical fields (B29C48/9165 takes precedence) · CPC title