Cellulose and cellulose ester film

Patent metadata

Field	Value
Publication number	US-11525215-B2
Application number	US-201916522989-A
Country	US
Kind code	B2
Filing date	Jul 26, 2019
Priority date	Aug 23, 2018
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

A film is made from a wet laid product containing cellulose fibers and cellulose ester fibers and a plasticizer. The film can be made by heat pressing the wet laid sheet to form a film having a continuous phase of cellulose ester resin and a discontinuous phase of cellulose fibers.

First claim

What we claim is:

1. A wet laid film comprising:
a. cellulose fibers, and
b. a continuous phase obtained from solvent spun cellulose ester (CE) staple fibers that have not been surface hydrolyzed and having:
i. a denier per filament (DPF) of 1.8 to less than 3, and
ii. a cut length of 3 mm to less than 6 mm, and
iii. crimping,

c. a plasticizer,

wherein the cellulose fibers and CE staple fibers are co-refined; wherein said CE staple fibers comprise cellulose acetate in an amount from about 4 wt % to less than 16 wt %; and wherein said cellulose ester staple fibers are crimped and have an average of 5 crimps per inch (CPI) or more.

2. The film of claim 1 , which comprises at least 10 wt. % of the plasticizer, based on the weight of the CE staple fibers.

3. The film of claim 1 , wherein the plasticizer comprises triethyl citrate, triacetin, or a polypropylene glycol-dibenzoate-benzoate ester.

4. The film of claim 1 , which has a thickness from 20 microns to 350 microns.

5. The film of claim 1 , wherein the film is obtained from a wet laid product that is subjected to a load of at least 200 pli.

6. The film of claim 1 , wherein the film is obtained from a wet laid product that is heated prior to applying a load.

7. The film of claim 1 , wherein the film is obtained from a wet laid product that is heated while applying a load, wherein the temperature applied is sufficient to cause the wet laid product to form a film.

8. The film of claim 1 , wherein the film is obtained from a wet laid product that is heated to a set point temperature of at least 75° C. under a load.

9. The film of claim 1 , wherein the film is a monolayer.

10. The film of claim 1 , wherein the film contains a discontinuous phase.

11. The film of claim 1 , wherein the film contains a discontinuous phase comprising the cellulose fibers randomly dispersed.

12. A film obtained from a wet laid product, said wet laid product comprising:
a. cellulose fibers, and
b. solvent spun CE staple fibers that have not been surface hydrolyzed and in an amount of 4 wt % to 16 wt %, based on the weight of all the fibers in the wet laid product, and having:
i. a denier per filament (DPF) of 1.8 to less than 3, and
ii. a cut length of 3 mm to less than 6 mm, and
iii. crimping,
and

c. a plasticizer in an amount of at least 5 wt. % based on the weight of the wet laid product; and

wherein said cellulose fibers and CE staple fibers are co-refined; wherein said CE staple fibers comprise cellulose acetate; and wherein said cellulose ester staple fibers are crimped and have an average of 5 crimps per inch (CPI) or more.

13. A process for forming a semi-finished film or finished film, comprising pressing a wet laid product comprising:
a. cellulose fibers, and
b. solvent spun CE staple fibers that have not been surface hydrolyzed but have been co-refined with said cellulose fibers, wherein said CE staple fibers are present in the wet laid product in an amount of 4 wt % to 16 wt %, based on the weight of all the fibers in the wet laid product, and having:
i. a denier per filament (DPF) of 1.8 to less than 3, and
ii. a cut length of 3 mm to less than 6 mm, and
iii. crimping,
and

c. a plasticizer in an amount of at least 5 wt. % wherein said CE staple fibers comprise cellulose acetate; and wherein said cellulose ester staple fibers are crimped and have an average of 5 crimps per inch (CPI) or more.

14. The process of claim 13 , wherein the plasticizer is applied to the wet laid product in a sizing zone in a wet laid machine zone.

15. The process of claim 13 , wherein less than the entire amount of plasticizer necessary to convert the wet laid product to a film is applied in a sizing zone in a wet laid machine zone.

16. The process of claim 14 , further comprising passing the wet laid product through nip rolls in an off-machine calender.

17. The process of claim 13 , which comprises unwinding a roll of the wet laid product without the plasticizer and applying the plasticizer to said wet laid product without the plasticizer prior to pressing.

18. The process of claim 13 , wherein the finished film contains a continuous phase of cellulose ester.

19. The process of claim 13 , wherein the CE staple fibers have an average of 10-25 crimps per inch, a cut length of less than 6 mm, and the ratio of cut length to DPF of the CE staple fibers is not more than 5:1.

Assignees

• Eastman Chem Co

Inventors

• Everett Charles Stuart
• Mitchell Melvin Glenn
• Parker Kenny Randolph

Classifications

• D21H15/02

  characterised by configuration · CPC title

• D21H5/2678

  Manufacture of layered products (assembly of superposed sheets), comprising the consolidation of such a structure (formation of a web by dry method directly on to other webs formed solely by dry method D21H5/2628 and subgroups) · CPC title

• D21H23/20

  Apparatus therefor · CPC title

• D21F1/40

  Rolls · CPC title

• D21H17/15

  Polycarboxylic acids, e.g. maleic acid · CPC title