US2606139A - - Google Patents

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US2606139A
US2606139A US2606139DA US2606139A US 2606139 A US2606139 A US 2606139A US 2606139D A US2606139D A US 2606139DA US 2606139 A US2606139 A US 2606139A
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United States
Prior art keywords
overlay
layer
panel
resin
wood
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic System
    • C07F9/02—Phosphorus compounds
    • C07F9/06—Phosphorus compounds without P—C bonds
    • C07F9/22—Amides of acids of phosphorus
    • C07F9/24—Esteramides
    • C07F9/2404—Esteramides the ester moiety containing a substituent or a structure which is considered as characteristic
    • C07F9/2433—Compounds containing the structure N-P(=X)n-X-acyl, N-P(=X)n-X-heteroatom, N-P(=X)n-X-CN (X = O, S, Se; n = 0, 1)
    • C07F9/2445—Compounds containing the structure N-P(=X)n-X-acyl, N-P(=X)n-X-heteroatom, N-P(=X)n-X-CN (X = O, S, Se; n = 0, 1) containing the structure N-P(=X)n-X-N (X = O, S, Se; n = 0, 1)

Definitions

  • the overlay has a relatively high concentration of resin on the outer surface and a relatively low resin concentration in the body, and a relatively high resin concentration at the line of junction with the plywood panel--the latter being provided for by the preliminary treating of the panel, as described above.
  • mold lubricant When the surface of the preliminarily compressed overlay is sprayed with resin, as just de-- scribed, more mold lubricant should be used, to prevent the material from sticking to the platen of the hot press.
  • the lubricant is preferably applied directly to the platen, but in some cases may be incorporated in the coating.
  • the silicone material known as Mold Release, sold by Dow Corning Company is satisfactory.
  • the final pressing operation may be performed in a. mulitple opening, steam heated hotpress l8 expanding gases to escape from the layer of overlay, without any danger of disruption thereof.
  • Theoverlay material is quite porous and includes a. great multiplicity of minute openings, betweenv the various wood particles. As the pressure is decreased, the gases created during the setting of the resin find their way through these pores or openings to the surface, and readily escape as the pressure approaches 'zero and while the platen is still in contact with the outer surface of the overlay.
  • the entire pressing cycle in the final pressing operation may be maintained as low as substantially three .minutes, depending on the thickness of the overlay and the temperatures and pressures employed.
  • the moisture content of the plywood portion' is often unduly low, because of the extra pressing operation to which it has been subjected.
  • This conditioning operation may be readily accomplished by subjecting the individual panels to currents of moist air for a suitaibleperiod of time to permittherplywdod tuabsorb. sufficient .moi'stureqto its content: up
  • the relatively high tensile strength and theimpervious character of the impregnated paper overlay materials give to these materials very different expansion and contraction characteristics, under changes in moisture content than the veneer plies.
  • the non-covered face of the plywood panel may absorb and give up moisture more rapidly than the covered face, with a resulting difference in expansion and contraction on the two faces of the panel.
  • the impregnated paper overlay, bonded to one surface .has such a tensile strength that the latter surface and the wood bonded to it cannot expand with the balance of the wood, and the panel warps and curves badly upon changes in moisture content.
  • the layer of discrete wood particles and synthetic resin is quite porous and has a low tensile strength.
  • the wood particles in the overlay itself absorb and give up moisture so that they expand and contract with the plywood part of the composite panel.
  • the wood particles in the overlay are not interlaced, entwined and felted together, as in the case with the libers in paper-like sheets or fibrous webs, they are not sufficiently interlocked to prevent slight movements between the fibers and equal expanscribed with particular reference to applying overlay materials to plywood panels, it must be understood that it is not limited thereto, as the novel procedures are of utility in applying overlays to other types of wood products, such as conventional lumber, as individual pieces or assembled into larger sheets or panels.
  • novel steps of coating the surface of the wood product with a thin coating of synthetic resin, applying the overlay to the coated surface, preliminarily compressing the overlay, applying a surface coating of resin to the preliminarily compressed mixture, and finally compressing the overlay under suiiicient heat and pressure to convert the resin may be employed for other purposes than providing an improved overlay on plywood.
  • the method of making a wood product having an overlay thereon which comprises applying to the surface of a wood sheet, a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an'aqueous synthetic resin solution, preliminarily compressing the layer under heat of at least substantially 250 F.
  • the method of making a wood product having an overlay thereon which comprises applying to the surface of a wood sheet, a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution, preliminarily compressing the layer under heat of at least substantially 250 F. and under pressure of at least substantially 30 pounds per square inch, for at least 5 seconds to compact the mixture and to prevent accidental disturbance of the layer during subsequent handling, completely releasing said preliminary compression and the application of heat, subsequently subjecting the wood sheet and the layer to greater heat and final pressure for a longer time to compact the layer and to convert the resin to the insoluble, infusible state and to bond the wood particles to each other and the layer as a whole to the surface of the Wood sheet,
  • the method of making a plywood product having an overlay thereon which comprises applying to at least one surface of the panel a thin coating of an aqueous synthetic resin solution, applying to the coated surface of the panel a smooth even layer of substantial thickness of a relatively dry mixture of discrete wood particles and an aqueous synthetic resin solution which is similar to and compatible with the resin of said coating, preliminarily compressing the layer under heat and pressure, completely releasing the preliminary application of pressure and heat after sufficient time and temperature to compact the mixture sufficiently to prevent accidental disturbance of the layer during subsequent handling of the panel, and subsequently subjecting the panel and the layer to greater heat and pressure for a longer time to convert the resins to substantially the insoluble, infusible state and to bond the wood-particles to each other and the layer as a whole to the surface of the panel.
  • the method of making a plywood product having an overlay thereon which comprises applying to the surface of the panel a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution, preliminarily compressing the layer under heat and pressure, completely releasing thepreliminary application of pressure and heat after sufiicient time and temperature to compact the mixture suificiently to prevent accidental disturbance of the layer during handling and to provide a substantially smooth, continuous, uniform upper surface on the layer, applying to the upper surface of the preliminarily compressed layer, a coating of an aqueous solution of a synthetic resin similar to the resin in said mixture and thereafter subjecting the panel, the layer and the coating to greater heat and pressure for a longer time to convert the resins to substantially the insoluble, infusible state and to bond the wood particles to each other and the layer as a Whole to the surface of the panel.
  • the method of making a plywood product having an overlay thereon which comprises applying to a surface of the panel a thin coating of an aqueous synthetic resin solution, applying to the coated surface of the panel a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution which is similar to and compatible with the resin of said coating, preliminarily compressing the layer under heat and pressure, completely releasing the preliminary application of pressure and heat after suffic-ient time and temperature to compact the mixture suiiiciently to prevent accidental disturbance of the layer during subsequent handling, applying onto the surface of the preliminarily compressed layer a coating of an aqueous solution of a synthetic resin similar to the resin used in the mixture, and thereafter subjecting the panel, the layer and said coating to greater heat and pressure for a longer time to convert the resin to substantially the insoluble, infusible state and to bond the wood particles to each other and the layer as a whole to the surface of the panel.
  • the method of making a plywood product having an overlay thereon which comprises applying to the surface of the panel a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution, preliminarily compressing the layer on the panel for from 5 to 10 seconds at 250 to 300 F.,'to compact the mixture sufficiently to prevent accidental disturbance of the layer during subsequent handling, completely releasing said preliminary compressing, and subsequently subjecting the panel and the layer to

Description

5 plate. Thusgthewax acts as a lubricantgfor the press platen and entirely eliminates all sticking .and'platefouling problems. Also, the plates of the hot press may be treated with lubricants capable ofwithstanding press plate temperatures to. prevent sticking or fouling problems.
.If, a. highly finished, hard, .glossy surface is desired on the overlay in the. finished product, Ihave discovered that this result may be accomplished by applying to the. upper surface of the preliminarily compressed overlay as indicated. at
20 in Figure 2b, a thin coating of the same'synthetic resin as is employed as the. binder the overlay .mixture. In some cases, the resin is mixed with an. equal volume of water and.
sprayed at the rate of 10. .lbs of resin per 1,030 square feet of overlay surface. In other cases, where a higher surface resin content is desired, the resin may be used. without dilution. and
sprayed at the rate of 15 or more lbs. of resin per thousand feet.
As. a'result of this procedure, and others herein described, the overlay has a relatively high concentration of resin on the outer surface and a relatively low resin concentration in the body, and a relatively high resin concentration at the line of junction with the plywood panel--the latter being provided for by the preliminary treating of the panel, as described above.
When the surface of the preliminarily compressed overlay is sprayed with resin, as just de-- scribed, more mold lubricant should be used, to prevent the material from sticking to the platen of the hot press. The lubricant is preferably applied directly to the platen, but in some cases may be incorporated in the coating. The silicone material known as Mold Release, sold by Dow Corning Company is satisfactory.
The final pressing operation may be performed in a. mulitple opening, steam heated hotpress l8 expanding gases to escape from the layer of overlay, without any danger of disruption thereof. Theoverlay material is quite porous and includes a. great multiplicity of minute openings, betweenv the various wood particles. As the pressure is decreased, the gases created during the setting of the resin find their way through these pores or openings to the surface, and readily escape as the pressure approaches 'zero and while the platen is still in contact with the outer surface of the overlay.
Thus, the entire pressing cycle in the final pressing operation may be maintained as low as substantially three .minutes, depending on the thickness of the overlay and the temperatures and pressures employed.
After the panels are removed from the hot press, the moisture content of the plywood portion'is often unduly low, because of the extra pressing operation to which it has been subjected. Hence, it is desirable to condition the panels. This conditioning operation may be readily accomplished by subjecting the individual panels to currents of moist air for a suitaibleperiod of time to permittherplywdod tuabsorb. sufficient .moi'stureqto its content: up
. from warping bending or cupping under variations in the moisture content .ofthepanel, such *as occurtiwhen the panel islater subject .to-jordinary variations in the humidityl'of the surrounding admo'sphere. Plywood having my overlay cnzone face only has the same characteristics', so far as warping, :etc., as the plywood itself. "This-ability toprovide the overlay on one surface only of the panel is an advantage of major commercial importance, since, in many usesof plywood panels, only one face is exposed, and. the appearance of the back face is a matter of complete indifference.
With plywood overlay materials in accordance with the prior art, it has been impossible, commercially, to produce panels having the overlay on only on surface, because of the resulting warping, cupping or other distortions in shape. For instance, with resin impregnated paper sheet overlays or the like, manufacturers have. been forced, in the commercial art, to apply the paper sheets or other fibrous webs to both faces of the panels, to prevent warping and bending thereof, irrespective of the use'to which the panels were to be put, and in spite of the additional cost of providing the extra overlay.
Although the technical explanation for these phenomena is not clearly understood, it is thought that the relatively high tensile strength and theimpervious character of the impregnated paper overlay materials give to these materials very different expansion and contraction characteristics, under changes in moisture content than the veneer plies. Hence, the non-covered face of the plywood panel may absorb and give up moisture more rapidly than the covered face, with a resulting difference in expansion and contraction on the two faces of the panel. Moreover, even if all of the wood plies absorb the same amount of moisture and tend to expand equally, the impregnated paper overlay, bonded to one surface, .has such a tensile strength that the latter surface and the wood bonded to it cannot expand with the balance of the wood, and the panel warps and curves badly upon changes in moisture content.
With an overlay produced in accordance with the present invention, however, the layer of discrete wood particles and synthetic resin is quite porous and has a low tensile strength. Hence,
moisture can permeate through the overlay so that both faces of the panel absorb and give up moisture at substantially the same rate. Apparently, the wood particles in the overlay itself absorb and give up moisture so that they expand and contract with the plywood part of the composite panel. Also, since the wood particles in the overlay are not interlaced, entwined and felted together, as in the case with the libers in paper-like sheets or fibrous webs, they are not sufficiently interlocked to prevent slight movements between the fibers and equal expanscribed with particular reference to applying overlay materials to plywood panels, it must be understood that it is not limited thereto, as the novel procedures are of utility in applying overlays to other types of wood products, such as conventional lumber, as individual pieces or assembled into larger sheets or panels. Thus, the novel steps of coating the surface of the wood product with a thin coating of synthetic resin, applying the overlay to the coated surface, preliminarily compressing the overlay, applying a surface coating of resin to the preliminarily compressed mixture, and finally compressing the overlay under suiiicient heat and pressure to convert the resin, may be employed for other purposes than providing an improved overlay on plywood.
I claim:
1. The method of making a wood product having an overlay thereon, which comprises applying to the surface of a wood sheet, a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an'aqueous synthetic resin solution, preliminarily compressing the layer under heat of at least substantially 250 F.
and under pressure of at least substantially 30 pounds per square inch, for at least seconds and completely releasing said preliminary compressing, thereby compacting the mixture sufficiently to prevent accidental disturbance of the layer during subsequent handling, and subsequently subjecting the wood sheet and the layer to greater heat and pressure for a longer time to compact the layer and to convert the resin to the insoluble, infusible state and to bond the Wood particles to each other and the layer as a whole to the surface of the wood sheet.
2. The method of making a wood product having an overlay thereon, which comprises applying to the surface of a wood sheet, a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution, preliminarily compressing the layer under heat of at least substantially 250 F. and under pressure of at least substantially 30 pounds per square inch, for at least 5 seconds to compact the mixture and to prevent accidental disturbance of the layer during subsequent handling, completely releasing said preliminary compression and the application of heat, subsequently subjecting the wood sheet and the layer to greater heat and final pressure for a longer time to compact the layer and to convert the resin to the insoluble, infusible state and to bond the wood particles to each other and the layer as a whole to the surface of the Wood sheet,
and gradually reducing the final pressure, to
permit the gradual escape of steam from the layer before entirely releasing the final pressure.
3. The method of making a plywood product having an overlay thereon, which comprises applying to at least one surface of the panel a thin coating of an aqueous synthetic resin solution, applying to the coated surface of the panel a smooth even layer of substantial thickness of a relatively dry mixture of discrete wood particles and an aqueous synthetic resin solution which is similar to and compatible with the resin of said coating, preliminarily compressing the layer under heat and pressure, completely releasing the preliminary application of pressure and heat after sufficient time and temperature to compact the mixture sufficiently to prevent accidental disturbance of the layer during subsequent handling of the panel, and subsequently subjecting the panel and the layer to greater heat and pressure for a longer time to convert the resins to substantially the insoluble, infusible state and to bond the wood-particles to each other and the layer as a whole to the surface of the panel.
4. The method of making a plywood product having an overlay thereon, which comprises applying to the surface of the panel a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution, preliminarily compressing the layer under heat and pressure, completely releasing thepreliminary application of pressure and heat after sufiicient time and temperature to compact the mixture suificiently to prevent accidental disturbance of the layer during handling and to provide a substantially smooth, continuous, uniform upper surface on the layer, applying to the upper surface of the preliminarily compressed layer, a coating of an aqueous solution of a synthetic resin similar to the resin in said mixture and thereafter subjecting the panel, the layer and the coating to greater heat and pressure for a longer time to convert the resins to substantially the insoluble, infusible state and to bond the wood particles to each other and the layer as a Whole to the surface of the panel.
5. The method of making a plywood product having an overlay thereon, which comprises applying to a surface of the panel a thin coating of an aqueous synthetic resin solution, applying to the coated surface of the panel a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution which is similar to and compatible with the resin of said coating, preliminarily compressing the layer under heat and pressure, completely releasing the preliminary application of pressure and heat after suffic-ient time and temperature to compact the mixture suiiiciently to prevent accidental disturbance of the layer during subsequent handling, applying onto the surface of the preliminarily compressed layer a coating of an aqueous solution of a synthetic resin similar to the resin used in the mixture, and thereafter subjecting the panel, the layer and said coating to greater heat and pressure for a longer time to convert the resin to substantially the insoluble, infusible state and to bond the wood particles to each other and the layer as a whole to the surface of the panel.
6. The method of making a plywood product having an overlay thereon, which comprises applying to the surface of the panel a smooth, even layer of substantial thickness of a mixture of discrete wood particles and an aqueous synthetic resin solution, preliminarily compressing the layer on the panel for from 5 to 10 seconds at 250 to 300 F.,'to compact the mixture sufficiently to prevent accidental disturbance of the layer during subsequent handling, completely releasing said preliminary compressing, and subsequently subjecting the panel and the layer to

Claims (1)

1. A COMPOSITION COMPRISING N-VINYL CARBAZOLE AND TETRAETHYLPYROPHOSPHATE.
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