Composition of matter feed to a head box

Patent metadata

Field	Value
Publication number	US-11512433-B2
Application number	US-201916522937-A
Country	US
Kind code	B2
Filing date	Jul 26, 2019
Priority date	Aug 23, 2018
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

A wet laid process includes a method for making paper in which a composition containing co-refined cellulose fibers and cellulose ester fibers made into a thick stock composition in a machine chest, the thick stock is fed to a cleaning/screening zone through a device that regulates the flow rate of thick stock, the consistency of the thick stock fed to the screening/cleaning zone is reduced to form a thin stock composition; the thin stock composition is subjected to a process for cleaning the thin stock and feeding the cleaned thin stock through screens to form a cleaned and screened thin stock composition, and the cleaned and screened thin stock composition is fed to a headbox.

First claim

What we claim is:

1. A process comprising:
a. providing a thick stock composition in a machine chest,
b. feeding the thick stock to a cleaning/screening zone through a device that regulates a flow rate of thick stock,
c. reducing a consistency of the thick stock fed to the screening/cleaning zone to form a thin stock composition;
d. subjecting the thin stock composition to a process for cleaning the thin stock and feeding the cleaned thin stock through screens to form a cleaned and screened thin stock composition;
e. feeding the cleaned and screened thin stock composition to a headbox,
wherein the compositions in steps a)-e) comprise cellulose fibers and solvent spun cellulose ester (CE) staple fibers that have been co-refined,
wherein the CE staple fibers that are subjected to co-refining have a minimum width of more than 1000 nanometers, have not been chemically treated to alter their chemical structure, and have:
i. a denier per filament (DPF) of 1.8 to less than 3,
ii. a cut length of 3 mm to less than 6 mm,
iii. crimping, and
iv. a non-round cross-sectional shape; and

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 process of claim 1 , wherein the thick stock has a consistency of at least 2.0 wt. %, and the thin stock has a consistency of less than 2.0 wt. %.

3. The process of claim 1 , wherein the thin stock is fed through, or dilution of the thick stock occurs at the feed to, a fan pump.

4. The process of claim 1 , wherein a broke pulp is added to the machine chest.

5. The process of claim 1 , where the composition in the machine chest is retained for a residence time sufficient to reduce consistency variability and de-aerate.

6. The process of claim 1 , wherein the thick stock if fed through a basis weight valve.

7. The process of claim 1 , wherein the thick stock is fed to a tickle refiner and stuff box.

8. The process of claim 1 , wherein the thick stock is diluted by adding whitewater obtained from a forming zone on a wet laid machine to the thick stock.

9. The process of claim 1 , wherein the thick stock comprises waste/recycle cellulose fibers.

10. The process of claim 1 , wherein the thin stock is fed at a consistency of 0.02 to 2.0 to a centrifugal cleaner.

11. The process of claim 10 , wherein the centrifugal cleaner comprises a hydrocyclone.

12. The process of claim 1 , the thin stock is fed to a pressure screen.

13. The process of claim 1 , wherein the thin stock is fed continuously to a headbox.

14. The process of claim 1 , wherein the thin stock is fed continuously to a headbox through which the thin stock is deposited onto a moving wire to form a wet laid web having a width of at least 5 feet.

15. The process of claim 14 , wherein the moving wire operates at a speed of at least 500 meters/minute (mpm), or at least 1000 mpm.

16. The process of claim 1 , wherein the process operates a production rate of at least 500 tons per day of wet laid product.

17. The process of claim 1 , comprising adding sizing agents after the thin stock exits step d) and prior to entering a headbox.

18. The process of claim 1 , wherein the weight ratio of cellulose fibers to CE staple fibers is at least 3:1.

19. The process of claim 1 , wherein the CE staple fibers have an average of not more than 0.5 fibrils per CE staple fiber.

20. The process of claim 1 , wherein the CE staple fibers have a cut length, and the ratio of cut length to DPF is not more than 5:1.

21. The process of claim 1 , wherein composition of claim 1 , wherein the composition fed to the headbox contains no plasticizer or not more than 0.3 wt. % plasticizer is added, based on the weight of the composition.

22. The process of claim 1 , wherein the CE staple fibers as added are obtained from solvent spun mono-component filaments.

23. The process of claim 1 , wherein the thick stock has a Canadian Standard Freeness of more than 350 and a Williams Slowness of less than 40 seconds.

24. The process of claim 1 , wherein the CE staple fibers have a shape factor of at least 1.5.

25. The process of claim 1 , wherein the CE staple fibers have a CPI of 10 to 20.

26. A process comprising feeding a composition to a headbox in a wet end section of a wet laid machine,
said composition comprising cellulose fibers and solvent spun cellulose ester (CE) staple fibers having a minimum width of more than 1000 nanometers,
wherein the cellulose fibers and the CE staple fibers have been co-refined, and
wherein the CE staple fibers have not been chemically treated to alter their chemical structure and have:
i. a denier per filament (DPF) of 1.8 to less than 3,
ii. a cut length of 3 mm to less than 6 mm,
iii. crimping, and
iv. a non-round cross-sectional shape; and
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.

Assignees

• Eastman Chem Co

Inventors

• Everett Charles Stuart
• Mitchell Melvin Glenn
• Parker Kenny Randolph
• Ghosh Koushik
• Izallalen Mounir

Classifications

• D21H15/10 Primary

  Composite fibres · CPC title

• D21F1/0018

  Devices for dispensing fibres in a fluid · CPC title

• D21F11/00 Primary

  Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines · CPC title

• D21F1/024

  Details of the feed chamber · CPC title

• D21H13/06

  Cellulose esters · CPC title