Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1995-10-06
1997-03-25
Chin, Peter
Paper making and fiber liberation
Processes and products
Non-fiber additive
162147, 162177, 162199, 162DIG4, D21H 2102
Patent
active
056140622
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for controlling the sedimentation of sticky impurities from paper stock suspensions in paper manufacture.
2. Discussion of Related Art
Even when paper was invented in the second century, the use of waste material, i.e. the technique of at least partial recycling, played a certain role. Nowadays, considerable significance is attributed to recycling technology through increasing ecological awareness. In view of the increasing production of paper, therefore, the supply of raw materials and the avoidance of waste are acquiring increasing significance.
By using secondary fiber stock from the recycling of wastepaper, savings can now be made in regard to raw materials, waste-disposal space and the energy required for paper manufacture. Unfortunately, this technology still involves specific difficulties.
Thus, in the processing of wastepaper, sticky impurities, normally known as stickies, can seriously disrupt the production process and adversely affect the quality of the paper produced. Stickies enter the papermaking process when the wastepaper used contains adhesive bonds, adhesive tapes or refined products, such as coated or laminated papers and paperboards. In addition, however, sticky impurities can also be formed by the resin in wood and through its interaction with paper auxiliaries.
Where the stickies are present in compact form, they can be mechanically removed relatively easily by means of sorting machines. In general, however, the stickies are present not only in compact form, but also in dispersed form in the pulp stock and are very difficult to remove in this form. Recently, therefore, the increasing use of wastepaper in paper manufacture and the restriction of the water circuits has increasingly resulted in a higher percentage of stickies in the circuit water.
Stickies cause a number of problems and disruptions not only in the papermaking process, but also in the processing of paper. On account of their stickiness, deposits are formed on machine parts, tube walls, sieves, wet felts, dry felts, drying cylinders, smoothing rollers, calender rollers and, in addition, even on the paper itself, resulting in web tears in the papermaking machine and in a deterioration in paper quality through holes, stains and marks (cf. H.L. Baumgarten, Das Papier, 1984, 38, No. 10A, pages V121-V125). According to H.L. Baumgarten, stickies in industrial and institutional publications have for years been the biggest problem in the recycling of wastepaper. Even minimum quantities of adhesive can cause tears in papermaking and printing machines, so that the machines have to be stopped for cleaning purposes. Baumgarten states: "2 g of adhesive at the right place in the papermaking machine can turn several hundred kg of paper into waste" (loc. cit., page V122, right-hand column).
Stickies have various origins. Essentially, they emanate from the resin in wood, from auxiliaries involved in paper manufacture, from binders for the coating of paper and cardboard, from adhesives for the processing of paper, from printing ink binders and from materials involved in the processing of paper. Stickies emanating from the resin in wood and from the adhesives used in the processing of paper are particularly important in the context of the problem addressed by the present invention.
The resins present in chemical wood pulp and mechanical wood pulp contain around 1 to 5% by weight of so-called harmful resins, depending on the type of wood. These resins may be present in colloidal, unbound form or may adhere to the paper fibers. According to J. Weigl et al., the difficulties caused by resin deposits in the manufacture and processing of paper have steadily increased in recent years for various reasons (cf. J. Weigl et al., Das Papier, 1986, pages V52-V62, more particularly page V53, left-hand column).
The adhesives used in the processing of paper may be divided into three groups, namely: contact adhesives, dispersion-based adhesives and hotmelt adhesives.
REFERENCES:
patent: 3081219 (1963-03-01), Drennen et al.
patent: 3102065 (1963-04-01), Thurlow
patent: 4744865 (1988-05-01), Dreisbach et al .
patent: 4781794 (1988-11-01), Moreland
patent: 4871424 (1989-10-01), Dreisbach et al.
patent: 4886575 (1989-12-01), Moreland
patent: 4919758 (1990-04-01), Wagle et al.
patent: 4923566 (1990-05-01), Shawki et al.
patent: 5055161 (1991-10-01), Hoffman
Wochenbl. Papierfabr., vol. 199, No. 3, 15 Feb. 1991, pp. 82-84.
H. L. Baumgarten, Das Papier, 1984, 38, No. 10A, pp. V121-V125.
J. Weigl et al., Das Papier, 1986, pp. V52-V62.
Wochenblatt fur Papierfabrikation 1993, pp. 163-170.
Wochenblatt fur Papierfabrikation 1990, pp. 310-313.
DIN 53282, 1995.
Eur.Comm. Communities 14011, 1992 pp. 235-243.
Hornfeck Klaus
Kaps Dieter
Schulte Heinz-Guenther
Chin Peter
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Szoke Ernest G.
LandOfFree
Process for controlling the sedimentation of sticky impurities f does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for controlling the sedimentation of sticky impurities f, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for controlling the sedimentation of sticky impurities f will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2200412