Method for producing wet-pressed, molded tissue products
View Patent ↗A process for producing tissue webs is disclosed. The process may include the step of partially dewatering a tissue web, subjecting the web to at least one deflection against a fabric, such as a coarse fabric, and then creping the web. During the process, after being dewatered, the tissue web is transferred from a transfer conveyor to the fabric using a pneumatic force, such as a suction force. In order to prevent liquids from rewetting the tissue web as the tissue web is being transferred to the fabric, the transfer conveyor is made from a material that inhibits or prevents liquids from flowing into the tissue web. For instance, in one embodiment, the transfer conveyor may comprise a felt comprised of small capillary materials. The felt may have an intake rate, for instance, of less than about 150 μL/s when wet, may have a mean free pore size of less than about 20 microns, and may have a minimum pore size of less than about 5 microns.
1. A method of producing a tissue product comprising:
depositing an aqueous suspension of papermaking fibers onto a forming fabric to form a wet web;
dewatering the wet web to a consistency of at least about 30%;
conveying the dewatered web onto a transfer felt, the transfer felt having an intake rate of less than about 150 μL/s;
transferring the web from the transfer felt to a fabric and deflecting the web against the fabric; and
conveying the web onto a drying drum and creping the web from the drum.
2. A method as defined in claim 1 , wherein the transfer felt has an intake rate of less than about 100 μL/s.
3. A method as defined in claim 1 , wherein the transfer felt has an intake rate of less than about 75 μL/s.
4. A method as defined in claim 3 , wherein the transfer felt has a mean free pore size of less than about 18 microns and has a minimum pore size of less than about 4.5 microns.
5. A method as defined in claim 3 , wherein the transfer felt has a mean free pore size of less than about 15 microns and has a minimum pore size of less than about 4 microns.
6. A method as defined in claim 1 , wherein the transfer felt has an intake rate of less than about 65 μL/s.
7. A method as defined in claim 1 , wherein the transfer felt has a mean free pore size of less than about 20 microns.
8. A method as defined in claim 1 , wherein the transfer felt has a minimum pore size of less than about 5 microns.
9. A method as defined in claim 1 , wherein the wet web is dewatered by being passed through a press nip.
10. A method as defined in claim 9 , further comprising the step of transferring the wet web from the forming fabric to a dewatering felt, the press nip being located between the dewatering felt and the transfer felt.
11. A method as defined in claim 10 , wherein the dewatering felt has an intake rate of less than about 150 μL/s, has a mean free pore size of less than about 20 microns, and has a minimum pore size of less than about 5 microns.
12. A method as defined in claim 1 , wherein the transfer felt comprises a felt material coated with a hydrophobic material.
13. A method as defined in claim 1 , wherein the web has a consistency of from about 30% to about 70% after being dewatered.
14. A method as defined in claim 1 , wherein the consistency of the web decreases by no more than 2% when the web is transferred from the transfer felt to the fabric.
15. A method as defined in claim 1 , wherein the consistency of the web decreases by no more than 1% when the web is transferred from the transfer felt to the fabric.
16. A method as defined in claim 1 , wherein the final dried web has a basis weight of from about 10 to about 25 gsm.
17. A method as defined in claim 1 , wherein the final dried web has a basis weight of from about 30 to about 80 gsm.
18. A method as defined in claim 1 , wherein a suction force against the fabric is used to transfer the web from the transfer felt and to deflect the web against the fabric.
19. A method of producing a tissue product comprising:
depositing an aqueous suspension of papermaking fibers onto a forming fabric to form a wet web;
conveying the wet web onto a dewatering felt and dewatering the web by passing the web through a press nip, the web being transferred onto a transfer felt after passing through the press nip, the transfer felt having an intake rate of less than about 150 μL/s, a mean free pore size of less than about 20 microns, and a minimum pore size of less than about 5 microns;
transferring the web from the transfer felt to a fabric and deflecting the web against the fabric, the web being transferred from the transfer felt to the fabric using a pneumatic force, the web decreasing in consistency by no more than about 2% when the web is transferred from the transfer felt to the fabric; and
conveying the web onto a drying drum and creping the web from the drum.
20. A method as defined in claim 19 , wherein the transfer felt has an intake rate of less than about 75 μL/s, has a mean free pore size of less than about 18 microns, and has a minimum pore size of less than about 4.5 microns.
21. A method as defined in claim 19 , wherein the transfer felt has an intake rate of less than about 65 μL/s, has a mean free pore size of less than about 15 microns, and has a minimum pore size of less than about 4 microns.
22. A method as defined in claim 19 , wherein the web decreases in consistency by no more than about 1% when transferred from the transfer felt to the fabric.
23. A method as defined in claim 19 , wherein the pneumatic force that transfers the web from the transfer felt to a fabric comprises a suction force placed against the fabric, the suction force deflecting the web against the fabric.
24. A method as defined in claim 19 , wherein the web has a consistency of from about 30% to about 70% after passing through the press nip.