US2048279A - Plywood and method of formation - Google Patents

Description

July 21, 1936. E. H. MERRITT PLYWOOD AND METHOD OF FORMATION Filed Jan. 18, 1952 2 Sheets-Sheet l INVENTOR July 21, 1936. MERRlTT 2,048,279

PLYWOOD AND METHOD OF FORMATION Filed Jan. 18, 1932 2 Sheets-Sheet 2 'INVENTOR Patented July 21, 1936 UNITED STATES z,o4s;279 rLYwoon AND METHOD or Foam-non Ericsson H. Merritt, Lockport, N. Y., assignor, by mesne assignments, to Laminating Patents Corporation, Seattle, Wash,

Delaware a corporation of Application January 18, weasel-m No. 587,217

10 Claims. (Cl. 154-2) Fig. 9 is an enlarged detail plan view of a corner This invention relates to plywood and to methods of forming the same, and, more particularly, to plywood embodying insulating board and methods for its formation. 1

An object of the invention is the provision of an improved laminated product comprising a veneer facing backed by structural insulation.

A further object is to provide a product of the character described which is especially resistant to marginal injury.

A still further object is to provide such a product which is sturdy and can be readily put in place.

Another object is the provision of an improved method of forming a product of the character under consideration.

A further object is to provide an improved method for uniting insulating board with natural wood. A still further object is to provide a method for securing a strong bond between wood and a layer composed of materials of greater absorbent qualities.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure,

and the scope of the application of which will be indicated in the claims.

- For a fuller understanding of the nature and objects of theinvention reference should be had to the following detailed description taken in connection with the accompanying drawings, in

which: I v

Figure 1 is a top'view of a section of plywood embodying the invention, with a portion of the face veneer cut away;

Fig. 2 is a sectional view along the line 2-2 in Fig. l;

Fig. 3 is a similar view of a two-ply structure;

of the lamination of Fig. 8 containing insulating board.

Structural insulating members composed of loose-texturedmaterial are well known and are available in a variety of forms. Among these are boards comprising shreds, fibers or other types of particles of wood. of various straws, of roots and the like, and other loose-textured composite boards having the heat and sound insulating l0 qualities desirable for structural work. For the sake of facility of expression the term "insulating board"'is used herein todescribe such products.

The use of such products faced by natural wood veneer has numerous advantages in con- 1 iailure to secure a proper bond between the veneer and the insulating board, weakness in the marginal edges, and particularly in the corners of the product, tendency toward cleavage along a plane parallel to the face of the product, and the fragility of the product when compared with natural wood.

With a view to overcoming the foregoing and other difficulties, the invention contemplates the provision of a laminated product including a layer of reinforced insulating board and the provision of an improved method of uniting an insulating board-containing layer to a teneer facing.

In accordance with the invention there is provided a plywood structure comprising a layer composed principally of insulating board reinforced by sections of a densematerial of the nature of wood. Examples ofsuch a material are natural wood and artificial woods having similar characteristics. for instance, boards formed from fibre or pulp and having a hard, dense structure imparted by relatively high pressure or otherwise. The reinforcing sections preferably extend transversely of the insulating board layer, i. e. from the front to the back thereof. The insulating board layer is faced and, preferably, also backed by a layer of veneer.

One example of a product such as contemplated by the invention is exemplified in Figs. 1 and 2.

This product comprises a core III, the major portion of which is composed of sections ll of insulating board.- with intemal and marginal reinforcing members l2 and I3, respectively, of

natural wood or the like. On either side 'of this core are facings l4 and i5 of veneer suitably united with the core by an adhesive.

' In instances where the veneer backing is unnecessary, this may be :omitted as indicated in Fig. 3, wherein there is shown a veneer facing I6 secured to a reinforced insulating board layer H, which is in this instance, constructed similarly to the layer ll] of Figs. 1 and 2. It may be noted in this connection, however, that when face and back veneers are utilized, a particularly sturdy product is secured.

There is shown in Figs. 4 and 5 a construction somewhat similar to that shown in Fig. 1.

In this instance only the parallel reinforcing' portions of natural wood are utilized, the lateral members being omitted. The insulating board layer is indicated at l8, the parallel reinforcing members at l9 and the veneer facing and back at 20 and 20'.

It is to be noted that in each of these cases reinforcement is provided at the corners of the panel. In some instances the reinforcing members may be omitted at all portions of the insulating board layer except the corners. A structure of this nature is shown in Figs. 6 and 7 wherein the insulating board layer is shown at 2| as embodying triangular reinforcing members 22 of natural wood or the like at each corner. The veneer facing and back are indicated at 23 and 23.

As will be understood, the reinforcing members may be arranged in numerous other ways without departing from the invention.

Due to the provision of reinforcing members, as indicated, it is possible to provide a structure which stands substantially the same stresses as a solid wood panel and will possess additional insulating properties. Moreover, the .wood sections are particularly adapted for easy nailing. Such a product, because of its rigidity, can be applied directly to the studding of a house and provide protection-against heat. cold and sound, and at the same time form a smooth surface which can be readily finished with paint or varnish. In such a panel, the tendency toward peeling, which is particularly marked when paint or varnish are applied to a surfacing veneer due to the strains set up, is greatly reduced where the face and back veneers are tied together by the reinforcing means.

In the formation of a panel including a layer of insulating board, the use of liquid glues has various disadvantages, among which is the excessive tendency of insulating board to absorb glue, and, when these contain a strong alkali, its tendency to attack the size and/or the cellulose fibres themselves, and to increase the absorbent action thereof. To avoid these and other diiliculties the invention contemplates the application of an adhesive base in powdered form to a surface to be glued. Any of a wide variety of types of adhesive .may be utilized, reference being made particularly to powdered casein, soya bean flour and powdered blood albumin, the latter being particularly desirable.

With a view to securing a particularly strong bond between the insulating layer and the veneer, the invention contemplates the pre-treatment of the reinforcing members. Such pretreatment preferably comprises applying to one or more of the surfaces thereof a bond-assisting liquid. Such liquid may comprise a heat-setting liquid glue, for instance, a wet blood glue, or a suitable bond-assisting chemical such, for example, as causticsoda in cases where proteinous adhesives such 'as those mentioned above are to v be utilized.

In the use of an adhesive, for instance those mentioned above, of a character such that the 5 plasticization thereof may be assisted by an alkaline reagent, a mild alkaline reagent may be provided at the glue line and a particularly strong alkaline reagent may be provided at the portion of the glue line where wood contacts with wood. 10

The mild alkaline reagent may be desirably supplied by mixing powdered lime with the adhesive before application, and the strong alkaline reagent may be desirably supplied by dipping the reinforcing inserts in a solution of caustic soda l5 orother strong alkali before association with the insulating section or sections, or by painting their surfaces after inclusion. Either reagent may be applied in any other suitable manner.

In the use of an adhesive plasticizable by wa- 20 ter, moisture may be provided in any suitable manner, as from one or the other of the layers if these contain suflicient water to yield up a supply to the adhesive, or by spraying one or both of the surfaces to be glued before and/or after the application of the powdered adhesive.

A specific form of procedure whereby articles embodying the invention may be produced and a method embodying the invention may be carried out is illustrated in Fig. 8. The reinforc 30 mg inserts are carried through a tank 24 containing a caustic soda solution indicated at 25 by means of a conveyor 26. Preferably, in the construction of articles such as shown in Figs.

1 and 2, the inserts are formed into a framework 35 as indicated at 21 and thus pass through the treating bath. Parallel to the conveyor 26 is a conveyor 28 on which veneer plies 29 are carried under material applying mechanisms indicated diagrammatically at 30, 3| and 32. The mechanisms 30 and 32 are indicated diagrammatically as a type disclosed in the copending application of Ericsson H. Merritt and Richard W. Stanley, Serial No. 535,822, filed May 8, 1931, and the mechanism 3| is indicated diagrammatically as of the type disclosed in the copending application of Louis G. Merritt and Ericsson H. Merritt, Serial No. 542,257, filed June 5, 1931. By this means the upper surfaces of the veneer plies are first moistened, after which there is applied powdered blood albumin with which hydrated lime has been admixed in a proportion of about one part by weight of hydrated lime to three parts by weight of blood albumin, and the powder is thereafter moistened by the mechanism 32. The pre-treated frame 21 is disposed on a veneer ply 29, after it has passed under the mechanisms 30, 3| and 32, and insulating board sections 33 are associated with the frame to complete the layer. A succeeding veneer ply 29 is turned over and placed upon the layer 34 formed by the members 33 and the frame 21. The completed assembly is thereafter subjected to bonding conditions. for example, to'a pressure of lbs. per square inch at 250 F. for 65 about thirty seconds, in a suitable veneer press portions occur.

Since certain changes in carrying out the above 75 method, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween..

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The method of forming plywood, which com- I prises applying a facing layer to a layer comp'osed principally of insulating board and containing sections of a dense material of the nature of wood, and subjecting to bonding conditions in the presence of an interposed adhesive in powdered form, said method including the step of pre-treating in a predetermined manner the wood sections of the insulating board layer with 'a bond assisting liquid prior to contacting the adhesive'therewith, said insulating board not being so pre-treated.

2. The method of forming plywood, which comprises forming a layer composed principally of insulating board and having incorporated therein sections of a dense material of the nature of wood, the surfaces of said sections aligned with the insulating board surface to be glued having been pre-treated with a bond-assisting liquid, providing a veneer layer, applying an adhesive in powdered form to the surface of one of said layers, assembling and subjecting to bonding conditions.

3. The method of forming plywood, which comprises forming a layer composed principally of insulating board and having incorporated therein sections of a dense material of the nature of wood, the surfaces of said sections aligned with the insulating board surfaces to be glued having been pre-treated with a bond-assisting liquid, providing veneer layers, applying an adhesive in powdered form to at least one of each pair of surfaces to be united, assembling and subjecting to bonding conditions.

4. The method of forming plywood, which comprises applying a layer of veneer to a layer composed principally of insulating board and containing sections of a dense material of the nature of wood, and subjecting to bonding conditions, said method including the step of applying to at least one of the surfaces to be joined a powdered adhesive material of such character that the plasticization thereof is assisted by an alkaline -re-agent, and the step of applying a strong alkali having the alkalinity of a strong solution which com/5 ers an adhesive base in powdered form, assem-- bling and subjecting to bonding conditions.

6. The method of forming plywood, which comprises dipping in a caustic soda solution inserts formed of a dense material in the nature of wood, forming a layer composed principally of insulating board and including said wood inserts, providing a veneer-layer, applying to saidveneer layer a powdered adhesive base which is of such character that the plasticization thereof is assisted by caustic soda and which is heat-coagulable, assembling and subjecting to heat and pressure.

7. The method of forming-plywood, which comprises dipping in 'a caustic soda solution inserts formed of a dense material in the nature of wood,

forming a layer composed principally of insulating board and including said wood inserts, providing a veneer layer, applying to one of said layers powdered blood albumin admixed with hydrated lime in a proportion of about one part of hydrated lime to three parts of blood albumin, assembling and subjecting to heat and pressure.

8. A method of forming plywood, which comprises providing a core composed principally of insulating board with transversely-extending inserts of a dense material of the nature of wood, providing a veneer facing, utilizing an adhesive base of a character such that the plasticization thereof in the presence of water is facilitated by an alkaline reagent, providing an alkaline reagent for the adhesive base, providing a stronger alkaline reagent for the adhesive base at said inserts, assembling and subjecting to bonding conditions. i

' 9. A method of forming plywood, which comprises applying an adhesive base in powdered form to a surface of each of a pair of veneer facings, forming on one ofsaid surfaces a core of insulating board having transversely-extending inserts of a dense material of the nature of wood pre-treated with a bond-assisting liquid, disposing the other of said surfaces thereupon, and subjecting to bonding conditions.

10. The method of forming plywood, which I comprisesapplying an adhesive base in powdered form to a surface of a veneer facing, forming a core of insulating board having transverselyextending inserts of a dense materialof the nature of wood pre-treated witha bond-assisting liquid, disposing said surface thereupon and subjecting to bonding conditions:

ERICSSON H. MERRITT.

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