Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1989-07-13
1992-07-28
Gallagher, John J.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
156 622, 156 628, 264112, 264113, 264128, B32B 516
Patent
active
051340267
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL BACKGROUND
The present invention relates to a process for the production of a pressure molded body of synthetic resin plastic in which a bonding agent with a condensation resin or condensation resin mixture based on phenols and/or amino compounds and aldehydes such as formaldehyde (if necessary, in liquid form is applied to dry or dried wood chips and/or fibers for impregnation and, if necessary in combination with other materials such as covering and/or intemediate layers, is hot pressed during the hardening of the resin. In addition, the present invention relates to initial products which can be used in such a process.
PRIOR ART
A process of the above kind is known from U.S. Pat. No. 4,503,115. This patent relates to a process for the production of a decorative structural panel in which one applies an aqueous akaline solution or dispersion of a phenol-formaldehyde resin to wood fibers, and then dries the resin coated wood fibers to a residual moisture content of 2 to 15%. A fiber mat is then formed from the resin coated, dried wood fibers, and this is then mechanically preconsolidated and hot pressed in one or a plurality of layers arranged one above the other to form a core layer; the decorative layer can be applied to the core layer simultaneously with the pressing process or thereafter.
This known process is intended to produce a structural panel that has properties similar to those found in molded laminated plastic panels produced in the usual way, which are made by hot pressing so-called "prepregs," that are made of paper impregnated, when dry, with hardenable synthetic resins. However, as a result of the preferred orientation of the cellulose fibers of the paper in the direction preferred during the production of such paper, under varying climatic conditions such molded laminated plastic panels display shrinkage and stretch behavior that differ in the longitudinal or transverse direction of the paper, and this can have a disadvantageous effect. In addition, the papers that are used in such panels are a material produced from wood raw material, using a process that is costly and harmful to the ecology.
The anisotropy in the stretch and shrinkage behavior, which has been noted above, is avoided in panels produced according to the process described in U.S. Pat. No. 4,503,115 and, in addition, since to a very great extent wood fibers are used in place of paper, one can lower production costs compared to the conventional production of molded laminated plastic panels. However, the drying of the resin coated wood fibers remains a costly stage in the process and is, in some instances harmful to the environment.
EP 0,035,133 B1 also describes the production of decorative laminates. In this process, a powdered phenol resin is introduced into a current of moist air in which cellulose-like fibers are dispersed, so that the fibers and the phenol resins mix. The mixture of wood fibers and phenol resin is then deposited on a sieve-like band in the form of a layer, which after preconsolidation is intended for use in the same way as a paper "prepreg" that has been impregnated with resin, for the production of the laminate. However, the use of powdered resin in such fiber "prepregs" entails several fundamental disadvantages. First, there is a danger that the fibers and the powdered resin will become segregated during storage and transportation within the framework of the production process. In addition, phenol resins in powder form have a smaller low-molecular component than liquid phenol resins. As a result, during subsequent hot pressing, the resin does not flow as well, which can cause insufficient wetting and penetration of the resin through the fibers.
DESCRIPTION OF THE INVENTION
Thus, it is the purposes of the present invention to disclose a process of the type discussed in the introduction hereto, in which the disadvantages of the known process can be avoided by using a resin bonding agent that flows well when used.
The task that underlies the present invention is solved by the process accor
REFERENCES:
patent: 3843431 (1974-10-01), Fostalik
Gallagher John J.
Isovolta Osterreichische Isolierstoffwerk Aktiengesellschaft
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