Plywood manufacture using foamed glues

• US 3,895,984 A
• Filed: 10/12/1973
• Issued: 07/22/1975
• Est. Priority Date: 10/15/1970
• Status: Expired due to Term

• Current Assignee: Charles N. Cone, Julius M. Steinberg
• Original Assignee: Charles N. Cone, Julius M. Steinberg
• Inventors: Cone, Charles N., Steinberg, Julius M.
• Primary Examiner(s): Whitby, Edward G.
• Application Number:
  US05/405,752
• Time in Patent Office: 648 Days
• Field of Search: 156/79.77,290,578,78,310,322,314 161/56,55,148,161 264/46.5
• US Class Current: 156/79
• CPC Class Codes: B05D 3/0218 Pretreatment, e.g. heating the substrate
• CPC Class Codes: B05D 5/10 to obtain an adhesive surface
• CPC Class Codes: B05D 7/08 using synthetic lacquers or varnishes
• CPC Class Codes: B27D 1/04 to produce plywood or articles made therefrom; Plywood sheets making a layered veneer cutting block B27L5/00
• CPC Class Codes: B27G 11/00 Applying adhesives or glue to surfaces of wood to be joined
• CPC Class Codes: B32B 21/13 all layers being exclusively wood
• CPC Class Codes: B32B 2607/00 Walls, panels
• CPC Class Codes: B32B 37/10 characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: Y10T 156/1744 Means bringing discrete articles into assembled relationship
• CPC Class Codes: Y10T 156/1798 with liquid adhesive or adhesive activator applying means

Abstract

Plywood is made by continuously propelling a liquid plywood glue in unfoamed condition at a predetermined flow rate, continuously foaming the glue as it is propelled, and continuously extruding or otherwise applying the foamed glue to the surface of a plurality of wood veneers. The flow rate of the unfoamed and foamed glue is maintained substantially the same on a unit weight of liquid glue per unit time basis. The veneers then are laid up into a plywood assembly and pressed, whereupon the pressure breaks the foam and unites the veneers. The method is applicable generally to the production of laminar products by the application of a foamed liquid to a solid surface.

Claims

1. The method of making a laminar product which comprises, a. continuously propelling in unfoamed condition and at a predetermined flow rate, a liquid comprising a liquid glue or liquid glue component, b. continuously foaming the liquid as it is propelled, c. continuously extruding the foamed liquid on the surface of a first sheet at a predetermined flow rate of foamed liquid and predetermined rate of traversal of extruded foamed liquid and surface relative to each other, d. applying a second sheet to the foamed liquid on said surface, e. at least one of said sheets being a porous cellulosic sheet, and f. pressing the resulting assembly under conditions predetermined to break the foam and create a substantially unfoamed glue bond uniting the sheets.

2. The method of claim 1 wherein the flow rates of the unfoamed and foamed liquid are maintained substantially the same, on a unit weight of liquid per unit time basis.

3. The method of claim 2 wherein the foamed liquid is extruded and deposited on the surface in laterally spaced filaments.

4. The method of claim 2 wherein the foamed liquid is extruded and deposited on the surface in laterally spaced filaments the filaments being stretchable and extruded by passing the filaments and the surface relative to each other at a relative rate such that the filaments are stretched as they are deposited in frictional engagement with the surface to an extent determining the magnitude of application of the liquid.

5. The method of claim 2 wherein the foamed liquid is applied to the surface by extruding it thereon in the condition of a substantillay continuous film.

6. The method of claim 2 wherein the liquid is foamed by feeding a foam-promoting gas into the liquid as it is propelled, and then mechanically agitating the resultant mixture of gas and liquid.

7. The method of claim 2 wherein the liquid is foamed by feeding a foam-promoting gas into the liquid as it is propelled and then mechanically agitating the resultant mixture of gas and liquid, by passing the mixture between a recessed rotor and stator in the direction of the axis of rotation of the rotor.

8. The method of claim 2 including the step of adding to the unfoamed liquid a material chemically reactive toward the liquid and thereafter immediately foaming the liquid and applying the foamed liquid to the surface in the time interval elapsing between the time of addition of the reactive material and the time required for substantial reaction with the liquid to occur.

9. THE METHOD OF MAKING PLYWOOD WHICH COMPRISES:

A. CONTINUOUSLY PROPELLING AN UNFOAMED LIQUID PLYWOOD GLUE AT A PREDETERMINED FLOW RATE, B. CONTINUOUSLY FOAMING THE LIQUID GLUE AS IT IS PROPELLED, C. CONTINUOUSLY APPLYING THE FOAMED GLUE TO THE SURFACES OF A SUCCESSION OF WOOD VENEERS, D. LAYING UP THE VENEERS INTO A PLYWOOD ASSEMBLY, E. AND PRESSING THE ASSEMBLY TO FORM A PLYWOOD PANEL, THEREBY BREAKING THE FOAM AND FORMING SUBSTANTIALLY UNFOAMED GLUE BONDS BETWEEN THE VENEERS.

10. The method of claim 9 wherein the foamed glue is applied to the veneer surfaces by extruding it thereon in the form of laterally spaced filaments.

11. The method of claim 9 including the step of preheating the veneers preliminary to applying the foamed glue.

12. The method of claim 9 wherein the plywood glue comprises a thermosetting resin glue and including the step of preheating the veneers preliminary to application of the glue on the surfaces thereof, the amount of preheating being predetermined to provide the heat required to set the glue during the pressing of the assembly substantially without the addition of supplemental heat from another heat source.

13. The method of claim 9 wherein the foamed glue is applied in the form of laterally spaced filaments, alternate filaments comprising first and second chemically reactive substances which are caused to mix and react with each other by the application of pressure occuring during the pressing of the assembly.

14. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a plywood blood glue and formaldehyde.

15. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a thermosetting resinous condensation product of a phenol and an aldehyde, and a setting catalyst therefor.

16. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a thermosetting resorcinol resin and paraformaldehyde.

17. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a thermosetting resinous condensation product of a phenol and an aldehyde and a thermosetting resinous condensation product of acetone and formaldehyde.

18. The method of claim 9 wherein the foamed glue is extruded onto the veneer surfaces at substantially the same flow rate as the propelled unfoamed liquid glue, on a unit weight of liquid per unit of time basis.