CS248227B1 - Veneer production method - Google Patents

Abstract

The subject of the solution is a method of producing veneers by thermal or thermochemical plasticization. The front surfaces of the cross-sections are preheated, then provided with a layer of plastic or organic material impregnated with plastics, reaction resins or oligomers at a temperature of 120 to 280 °C at a pressure of 0.05 to 1.0 MPa for 3 to 40 seconds. After hardening or drying, the log or prism is mechanically divided into veneers, which are stronger and have a smaller number of end cracks than previously produced veneers.

Description

The object of the solution is the method of veneer production by thermal or thermochemical plasticization. The cross-sectional faces are preheated, followed by a layer of plastic or organic material impregnated with plaist, thermosetting or oligomers at a temperature of 120 to 280 ° C at a pressure of 0.05 to 1.0 MPa for 3 to 60 seconds. After curing or drying, the log or prism is mechanically divided into veneers which are firmer and have fewer terminal cracks than doiposial veneers.

The present invention provides a process for the production of veneers from logs or hiranols from wood with thermal or thermochemical plasticization.

In the known methods for producing ornamental veneers from solid wood logs or logs, the wood is mechanically separated by metal tools by peeling, eccentric peeling or slicing. In the case of most woody species, it is necessary to plasticize the wood mass prior to mechanical separation, which is carried out practically exclusively by the effect of heat and water, or by thermo-chemical plasticization. After peeling or tarayani, the veneers are either wound or cut! and then folded into files or transported directly to the driers.

During the actual mechanical separation, winding, shearing, folding of the wet veneers into bundles, the storage and transport of the wet veneers to the dryer, but especially during drying, the water from the veneers is unevenly evaporated. As a result of the fact that the permeability of the wood in the direction of the fibers is substantially higher in the tangential and radial directions, and because the veneer surfaces are largely covered, the evaporation rate from the front surfaces is higher.

As a result of uneven fumes, anla cracks in veneers. In the production of ornamental veneers, an attempt is made to move to the smallest depths, which are currently in the range of 0.8 to 0.2 mm. During transport and handling of these veneers they often suffer mechanical damage.

The disadvantages of the present state are largely eliminated by the process for the production of veneers according to the invention, which is based on the fact that the cross-sectional faces of logs or beams of 20 to 210% moisture are preheated at a temperature of 120 to 400 ° C for 3 to 60 seconds, the faces are then coated with a plastic or fibrous organic material impregnated with plastics, reactants or oligomers at a temperature of 120 to 280 ° C and a pressure of 0.05 to 1.0 MPa for 3 to 60 seconds with a thickness of 0.2 to 5 millimeters and after hardening or drying, the log or prism is mechanically divided into veneers.

The advantages and the higher effect of the veneer manufacturing process according to the present invention are that the faces of the massive trunks or prisms are reinforced during peeling or slicing with a layer of synthetic polymer or even reinforcing fibrous organic material that prevents moisture from escaping from the foreheads. The reinforcing layer on the cross-section of the massive trunk or hr, anola prevents to a large extent the formation of end cracks of veneers during mechanical separation, drying, transport and handling.

Example 1

The prism of the walnut treated by plasticization in the steaming pit has a moisture content of 60%. A metal plate of the heater having a surface temperature of 350 ° C for 60 seconds is pressed onto the faces of the prism aligned by milling. Then the faces at 200 ° C are coated with a layer of ethyl vinyl acetate hot melt adhesive heated to 210 degrees C and pressed onto the faces for 10 seconds at 0.08 MPa. After solidification of the plastic with an average thickness of 1.5 mm, the prism with stiffened faces is cut to a veneer depth of 0.6 mm. The veneers produced have a lower number of end cracks and are more resistant to mechanical breakage during handling.

P r i, k 1 and d 2

The beech tree prism has a moisture content of 110% after plasticization in the steaming bell. After aligning the faces of the prism by milling, a metal plate of the heater having a surface temperature of 300 ° C for 60 seconds is pressed onto them. Subsequently, a 1.5 mm thick polyethylene foil is pressed onto the preheated faces of 200 ° C and pressed at 260 ° C for 20 seconds at a pressure of 0.05 MPa.

The veneer production method according to the invention can be used in all woodworking composites for the production of sliced veneers, in particular rare ornamental trees, but also in the production of peeled veneers.

Claims (1)

OBJECT A method of producing wood veneer or prism wood veneers with thermal or thermo-chemical plasticization by the action of heat, water, steam or chemicals, followed by mechanical veneer splitting, characterized in that the frontal areas of the logs or prisms of 20 to 210% moisture are preheated to a temperature of 120 to 400 degrees C for 3 to 60 seconds, followed by a front layer of plastic or fibrous organic material impregnated with plastics, rewetlastics or oligomers at a temperature of 120 to 280 ° C and a pressure of 0.05 to 1.0 MPa for 3 to 60 seconds with a thickness of 0.2 to 5 mm, and mechanical curing of the stem or prism into veneers when cured or dried.