Paper making and fiber liberation – Processes and products – With coating after drying
Patent
1997-02-13
1999-08-24
Silverman, Stanley S.
Paper making and fiber liberation
Processes and products
With coating after drying
162183, 1621683, 162166, 162175, 427391, D21H 2376, D21H 1728, D21H 1737, D21H 1744
Patent
active
059420863
DESCRIPTION:
BRIEF SUMMARY
The present application claims priority to UK Application No. 9416520.6 and UK Application No. 9419323.2.
TECHNICAL FIELD
The present invention concerns improvements in or relating to the application of material to a substrate and the insolubilization of material. More particularly, the present invention is concerned with a process for improving the characteristics of a substrate by the application of material thereto. In particular, the present invention will be described in relation to its preferred embodiment in which the present invention is directed to a process for adding material to paper during production thereof to increase the strength of the paper so produced.
BACKGROUND ART
In the preparation of various substrates, techniques have been developed to increase the strength of the substrate by insolubilizing materials onto the substrate to reinforce the substrate. One example of such a substrate is paper. In the production of paper, cellulose has been pulped in a slurry, and the slurry applied to a screen to orient the fibers and drain away liquids. Typically from the screen the paper is then squeezed between rollers to further reduce the water to produce a sheet of paper after suitable drying. The strength of the paper produced is dependent upon the nature of the pulp. For example, Virgin pulp of a given quality typically produces a much stronger paper than pulp from repulped paper of the same quality. Also, the strength achievable from the pulp decreases with each recycling evolution. Thus, there has always been an interest in additives which could increase the strength of the paper. Strength of the paper heretofore has been increased either by use of a size press operation or by wet end addition. The main concern is to eliminate size press additions because it is extremely inefficient from both a production and energy content standpoint. Typically, size press additions have been conducted by wetting the finished paper of flooded rollers with a starch solution to soak the starch into the paper subsequent drying thereby increasing the strength of the paper. This procedure suffers several drawbacks, among of them being, there is a limited amount of starch which can be added in this manner, thereby limiting the strength increase possible since the sheet can only absorb a fixed amount of solution. Furthermore, size presses are a large capital item requiring large amounts of space when coupled with the extra dryers required to redry the sheet.
Paper consumption has increased worldwide and is expected to increase further. A large portion of solid waste generated is paper and paper products. Many nations have undertaken efforts to reduce all types of waste products including paper in order to conserve landfill space. As a result, there is increasing interest and desire to recycle paper products. One disadvantage and limitation heretofore on the recycling of paper was the inability to achieve the desired strength of paper made in whole or in part from recycled pulp. The difficulties in achieving sufficient strength will become magnified as it is attempted to recycle paper which has already been recycled one or more times. Indeed in Europe where recycling is more intensive than in the United States it has become commonplace practice to make certain grades of paper entirely from recycled fiber especially in the boxboard grades.
The products are made from recycled boxes and mixed waste without the use of any virgin fiber and for certain grades e.g. fluting grade paper it is impossible to make the quality standard required without a large increase in the stiffness parameter as measured by the concorra medium test (CMT) or latterly the STFI test. To effect such improvements as is necessary, the mills have been forced to add starches by means of a size press in amounts varying between 3% and 10% based on fiber. To date it has been generally accepted that wet end addition of conventional reinforcing agents such as starches, carboxymethyl cellulose, polyvinyl alcohol etc., in various states of charge densi
REFERENCES:
patent: 3180787 (1965-04-01), Adams
patent: 3264174 (1966-08-01), Aitken et al.
patent: 3459632 (1969-08-01), Caldwell et al.
patent: 4094736 (1978-06-01), Malden
patent: 4272297 (1981-06-01), Brooks et al.
patent: 4501641 (1985-02-01), Hirakawa et al.
patent: 4643801 (1987-02-01), Johnson
patent: 4820582 (1989-04-01), Merz et al.
patent: 4925530 (1990-05-01), Sinclair et al.
patent: 4961825 (1990-10-01), Andersson et al.
patent: 5098520 (1992-03-01), Begala
patent: 5104487 (1992-04-01), Taggart et al.
patent: 5126014 (1992-06-01), Chung
patent: 5129989 (1992-07-01), Gosset et al.
patent: 5250153 (1993-10-01), Izard et al.
patent: 5338406 (1994-08-01), Smith
patent: 5792317 (1998-08-01), Taylor et al.
Koethe et al., "Polyelectrolyte interactions with papermaking fibers: the mechanism of surface-charge decay," Tappi Journal, vol. 76, No. 12, Dec. 1993.
Boardman, "Some practical observations on the use of cationic agents in the control of interfering substances," Tappi Journal, vol. 76, No. 12, Dec. 1993.
Abstract 61263796; Nov. 21, 1986; Japan.
Abstract 58031199; Feb. 23, 1983; Japan.
Advisory Search Report to United Kingdom Patent Office.
PCT International Preliminary Examination Report.
TAPPI--vol. 60, No. 12, Dec. 1977; pp. 148-149; Carr, M.E. et al "A Polsat Complex for Wet-end Addition".
Fortuna Jos'e A.
Philip Chem-Solv, Inc.
Silverman Stanley S.
LandOfFree
Application of material to a substrate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Application of material to a substrate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Application of material to a substrate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-463380