Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1997-11-26
1999-12-28
Yao, Sam Chuan
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
264109, 264122, 28104, 156 622, D04H 100, D04H 502
Patent
active
060076534
DESCRIPTION:
BRIEF SUMMARY
FILED OF THE INVENTION
This invention relates to a manufacturing method of nonwoven materials where a web is formed using an air laying method after which the web is both prebonded and hydro entangled, and to a nonwoven material manufactured according to the method. More particularly, this invention relates to nonwoven materials made from natural fibers such as wood fiber or from natural fibers and plastic fibers. The nonwoven materials have good absorbency, softness and strength properties. Particularly, but not exclusively, this invention relates to a nonwoven material which can be used for wet wipes or for the surface layers of absorbent disposables such as childrens' diapers, feminine pads and incontinence products, among others.
BACKGROUND OF THE INVENTION
In the manufacture of air laid nonwoven materials, natural fibers are used to form a web onto which a bonding agent or bonding fibers are applied which under the influence of heat bind the formed web into a porous material layer. Such layers are formed on top of each other including as many as the desired thickness of the product requires. Material layers produced as described are used in the manufacture of various table top, hygiene, hospital and wipe products. The problem with these types of products, however, is their often inadequate strength, resulting in breaking of the products or deleterious dusting of fibers.
In the manufacture of spunlaced nonwoven material, the fibrous structure is created by using fine water jets to entangle the fibers of a fibrous web with each other. These jets are directed at the fibrous layer supported by a liquid permeable wire moving in a specific speed. When the fibers pass under the jets, the liquid jets penetrating the layer impinge the fibers. The joint influence of this and of the jets reaching the wire causes the fibers to entangle with each other. This method can be used to produce nonwoven fabrics from fibers of different origin selected on the basis of their intended usage, as long as the fibers minimum length is adequate. However, the problem with this type of a process is often that short fibers are flushed out or that they pass through the wire, which causes fiber loss, cleaning problems and extra costs.
SUMMARY OF THE INVENTION
This invention relates to a method that can be used to create from low-cost raw materials a nonwoven material with good absorbency, softness and strength and that, if necessary, can be manufactured so that it decomposes quickly, for example, in a natural environment. A method according to the present invention is characterized in that the manufacture of the nonwoven comprises the following stages: blend of natural fibers and bonding fibers; applying a liquid bonding agent to the fibrous web and bonding it with thermal bonding, or by moisturizing the fibrous web and bonding it with heated calenders;
Thus a low-cost nonwoven according to the present invention is produced stage-by stage in a production line that comprises the aforesaid stages. Good absorbency, softness and low raw material costs are based on the large proportion of wood fibers. Extremely good biodegradability can be achieved by using merely wood fiber, such as mechanical or chemical pulp, and in addition, if necessary, a small amount of rayon fiber. To the surprise of the applicant, prebonding prevents fibers from flushing during spunlacing. Spunlacing produces the good strength of the web while maintaining good absorbency and softness.
Thus, the surprising result is that the nonwoven produced is absorbent, soft and strong. Raw material costs of the nonwoven are low and the nonwoven can be manufactured, if necessary, so that it has very good biodegradability.
Other preferred embodiments of the method according to the present invention are characterized by what is stated in the claims. A nonwoven material according to the present invention and its preferred embodiments are also characterized by what is stated in the claims.
BRIEF DESCRIPTION OF THE FIGURE
The invention is described with the help of the fol
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Niemi Tapio
Pirinen Pentti
UPM-Kymmene Oyj
Yao Sam Chuan
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