Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1999-03-16
2000-04-11
Nutter, Nathan M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
442 63, 442327, 442414, 426 77, 426138, B32B 502, B32B 2704, B32B 2712, D04H 100, D04H 300
Patent
active
060489170
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a cellulose-bonded nonwoven fiber fabric and a process for the production thereof. It further relates to the use of this nonwoven fiber fabric for the production of food packaging, in particular teabags or sausage casings.
Fiber-reinforced seamless cellulose casings are usually produced by the viscose process. In this process, a nonwoven fiber fabric, for example made of hemp fiber paper, which has been formed into a tube is coated on the inside and/or outside with an alkaline viscose solution. The material coated on the inside, outside or both with viscose thus produced is then treated with an acidic coagulation liquid which precipitates the cellulose xanthogenate and regenerates it to form cellulose hydrate. Generally, enough viscose solution is applied to cover the nonwoven fiber fabric completely on one or both sides with a layer of regenerated cellulose. Fiber-reinforced cellulose casings are very widely used as sausage casings.
It is also known to coat with viscose flat webs made of a nonwoven fiber fabric. In this process, the viscose-coated material is coagulated in the manner described and regenerated. The fiber-reinforced cellulose flat films may likewise be processed into tubular casings if they are appropriately bent and the edges sewed together, glued or sealed. Such casings are also suitable as sausage casings.
The nonwoven fiber fabric is produced in a usual manner from cellulose fibers. To increase its strength, it is generally bonded. Thus U.S. Pat. No. 3,135,613 discloses the production of a wet-strength hemp fiber paper. The increased strength is achieved by treatment with a dilute alkaline viscose solution, drying and regeneration of the cellulose using dilute sulfuric acid. The paper is then washed until it is acid-free and is finally dried. The regenerated cellulose coating serving as bonding is so thin that the porous structure of the paper is retained.
However, a pure cellulose bonding is not sufficiently alkali-resistant and stable to hydrolysis. During a subsequent coating of the paper with alkaline viscose solution, the existing cellulose again partially dissolves and the fibers loosen. Tubular films having a fiber reinforcement of this type therefore have a tendency to burst, even at a low internal pressure.
To avoid this disadvantage, nonwoven fiber fabrics have also been used which are set solely with synthetic resins. According to GB-A 1 091 105, the cellulose fibers are bonded with an alkali-curable resin, for example a polyethyleneimine resin or an epichlorohydrin-crosslinked polyamide. In U.S. Pat. No. 3,484,256, for this purpose use is made of a mixture of a cationic heat-curable resin and a polyacrylamide. Cellulose casings reinforced with this material do not guarantee the bursting strength which is demanded for certain sausage types.
Resin bonds are generally not sufficiently heat stable. The viscose solution can in addition not penetrate resin-bonded nonwoven fiber fabrics sufficiently. Furthermore, the resin causes the regenerated cellulose to adhere insufficiently to the fibers.
The object of the invention is to provide in an environmentally compatible manner a nonwoven fiber fabric which has wet strength, is alkali- and hydrolysis-resistant, is optimally penetrated by the viscose and bonds firmly to regenerated cellulose hydrate. In particular, the tubular food casings produced therefrom by viscose-coating are to have an optimum strength, extensibility and swellability, as well as a good shrinkage behavior.
This object is achieved by a nonwoven fiber fabric whose fibers were bonded by N-methylmorpholine N-oxide (NMMO) and water,
The nonwoven fiber fabric can, as is customary, be produced by running a screen through a fiber pulp and then partially or completely drying the resultant nonwoven fiber fabric. The fiber pulp preferably comprises from about 0.1 to 2% by weight of cellulose fibers, hemp fibers being preferred. Other constituents, such as resins or sizes, can also be further added to the fiber pulp. The nonwoven fiber fabric can also
REFERENCES:
patent: 3135613 (1964-06-01), Underwood
patent: 3484256 (1969-12-01), Chiu et al.
patent: 4246221 (1981-01-01), McCorsley, III
patent: 4868227 (1989-09-01), Kempter et al.
patent: 5824115 (1998-10-01), Kubota et al.
Grolig Gerhard
Hammer Klaus-Dieter
Kalle Nalo GmbH & Co. KG
Nutter Nathan M.
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