US2658878A - Structural board from wood waste, extracted flour of soya beans and melamine-urea formaldehyde resin - Google Patents

Description

UNl'l-.. OFFICE STRUCTURAL BOARD FROM WOOD WASTE, EXTRACTED FLOUR OF SOYA BEANS AND MELAMINE-UREA FORMALDEHYDE RESIN Joseph N. Sears, Sacramento, Calif., assignor to L. J. Carr & 00., Sacramento, Calif., a partnership No Drawing. Application October 10, 1949, Serial No. 120,603

3 Claims, (Cl. 260--6) This invention is directed to, and it is an object to provide, a novel dry-thermo pressed structural board, in sheet form, produced from woodwaste.

Another object of the invention is to provide a dry-thermo pressed structural board whose principal constituents are wood-waste ground or milled to a selected particle size, and a novel protein binder effective under conditions of heat and pressure to bond the wood particles into a structural board having desirable characteristics with respect to surface finish, density, and strength. The board is relatively water-resistant; has good dimensional stability; and excellent fiexural and impact strength due to high density.

A further object of the invention isto provide a dry-thermo pressed structural board, as above, wherein the protein constituent is the extracted flour of soya beans; such protein being used as the primary binder, and it is found to serve the purpose in an exceedingly effective manner even though present in small proportion relative to the reduced wood-waste.

An additional object of the invention is to provide a dry-thermo pressed structural board which embodies, in addition to the reduced wood-waste and protein binder, other initial constituents including a resin binder, a humectant and lubricator, a fire retai dam, and a fl ng As distinguishe F631 'dtirer pressed structural boards, the above fire retardant and fungicide are distributed uniformly throughout the board *rather than merely a surface application as is conventional.

A further object of the invention is to provide a dry-thermo pressed structural board which is capable of ready and economical manufacture; the novel processing or method of production being relatively simple, and designed for mass production of the board.

It is also an object of the invention to provide a dry-thermo pressed structural board in sheet form which can be sawed, machined, sanded, and otherwise handled in the same manner as wood, buthaving no grainis not subject to splitting.

Still another object of the invention is to provide a practical, reliable, and convenient to use structural board, and one which will be exceedingly effective for the purpose for which it is de- Signed.

These objects are accomplished in the manner and by the method as will fully appear by a perusal of the following specification and claims.

Referring now more particularly to the details of the structural board and the method of manufacturing thereof, a preferred or standard formula for the same is as follows:

Per cent Reduced wood-waste 90.40 Solvent-extracted flour of soya beans 5.00

? Melamine-urea formaldehyde 1.00 Ammonium phosphate 1.25 Ammonium sulfate 1.25 Boric acid .75 Ethylene glycol .10 Pentachlorphenate .25

ject to some variation, as for example:

Per cent Reduced wood-waste 86.65

Solvent-extracted flour of soya beans 8.00

Melamine-urea formaldehyde 1.50

Ammonium phosphate 1.25

Ammonium sulfate 1.25

Boric acid .75

Ethylene glycol .10

, Pentachlorphenate .50

In the formula immediately above the protein and other ingredients, exclusive of the Woodwaste, remain however in relatively small proportion to the latter.

The following is a more particular description of each of the ingredients which comprise the formula:

i. RM.

The selected wood-waste can be the lumber production waste from all hard or soft wood operations, and the initial physical form of the wood-waste may be sawdust, chips, shavings, blocks, or slabs. The selected wood-waste is processed in quantity through an interplane' grinder or hammermill, with the resulting particle size subject to selective control. Where it is desired that the resultant structural board be very smooth, with little or no flexibility, the wood waste is reduced to very fine particles comparable to sanderdust or fine sawdust.

For a less smooth surface but a greater moisture resistance and greater fiexural and impact strength, the wood-waste is hammermilled to approximately /20 particle size.

Coarser wood-waste can be made into a structural board by the present formula but the board, while having excellent fiexural and tensile strength, has reduced dimensional stability and a rough surface.

The reduced wood-waste from an interplane grinder produces a Waste which has long fine fibers. This is desirable, as the long fiberswhen fed into a matcause a heterogeneous arrangement with the fibers crossed several times by other fibers. This fiber arrangement produces a structural board of highest possible moisture resistance, dimensional stability, tensile strength, and impact and flexural strength, as well as a uniform smooth surface. It is therefore preferred that the reduced wood-waste be processed in a reduction apparatus which produces waste having the aforesaid long, fine fibers.

The protein in the formula serves as the primary binder, and such protein is the solvent extracted flour of soya beans. The solvent extraction removes substantially all of the oil from the soya flour, without causing the meal to be heated to the excessive temperatures required in the expelled meal process. The flour as used in the formula contains approximately 60% protein, 5% moisture, 4% fiber; 1% oil, and organic combinations of potassium, calcium, magnesium, sodium and iron.

The melamine-urea formaldehyde is a resin binder composed of one part melamine to one part urea. These two chemicals are combined with formaldehyde and conventional plasticizers and are blended with the dr powdered resin. The melamine-urea formaldehyde serves the purpose of a secondary binder, being desirable because of its ability to flow during the thermopressing operation, and additionally imparts greater water resistance and impact strength to the board.

The ammonium phosphate used is the secondary ammonium phosphate or diammonium hydrogen phosphate (NH4) zHPOi. This salt is used in conjunction with the ammonium sulfate and boric acid for enhancing the fire resistant quality of the structural board.

The ammonium sulfate (NI-1029,04 is the inexpensive commercial grade and the boric acid (or orthoboric acid) H3BO3 is also the commercial grade of granular acid.

The ethylene glycol (HO.CI-I2.CH2OH) is used as a humectant and lubricator in the board formulation.

The sodium pentachlorphenate is a water soluble sodium salt of pentachlorphenol which reacts with the acid carbon dioxide from the air to make a water insoluble and equally toxic pentachlorphenol. This pentachlorphenol is very stable and serves in the board as a fungicide, giving resistance to organisms such as Cerwtostomella pilz'fera, Hormonema dematiodes, Fomes roseus, etc., as well as resistance to rodent and termite damage or destruction.

The following steps are employed as the method of manufacture of the dry-thermo pressed structural board:

The selected wood-waste is milled in quantity and to a predetermined particle size, as heretofore described, in an interplane grinder or hammermill, and is then sprayed with a water mixture solution of the ethylene glycol and sodium pentachlorphenate; the solution being sprayed 4 onto the milled woodwaste at a calculated rate to bring the total moisture to 10-12% by weight.

The relativel dry, milled wood-waste is then blown into a cyclone which has a helicoid volumetric conveyor at the bottom thereof, the helicoid being set to deliver a volume of woodwaste equal to approximately 92% of the total required mix for the subsequent press cycle of the board production. Following delivery from the helicoid the wood-waste is admixed with the dry premixed chemicals (protein, plastic, phosphates, sulfate, and boric acid) in any suitable type of dry mixer.

From the dry mixer the total mixture is deposited on a conveyor and fed to a storage hopper.

The mixture is delivered from such storage hopper to a mechanical feeder which is operative to feed the mixture in the form of a mat onto steel forming and pressing trays; such mechanical feeder including a horizontal strike-off device which assures that the mat of the mixture on the forming and pressing trays is of predetermined and uniform thickness. This is desirable so that the resultant board will have uniform thickness throughout.

After the mat of the mixture has been placed on the forming and pressing trays such mat is subjected-4n a press-to a platen pressure of 5002500pounds per square inch for a period of approximately five minutes at a platen temperature of 280-290 F.

At the end of the pressing period the press is opened and the hot finished structural boards are removed from the press and the trays. The boards after cooling are trimmed to the desired size, packaged, and warehoused.

The action or reaction of the protein binder with the milled wood-waste under the conditions of pressure and heat in the press is very complex, but the following is believed to be generally the chemistry of the process:

The amount of protein existent in the milled wood-waste is fortified or extended with the extra protein, such as flour of soya beans, introduced into the mixture, and on the hydrolysis accomplished in the press the proteins give a mixture of amino acids and cause a bonding action, which in turn results in the soluble protein becoming insoluble. The alkaloids in the wood-Waste are, by this acid reaction, made soluble and are moved closer to the surface of the board, making a very toxic outer shell on said board. Further, it has been found that the other organic acids (fatty and resin) in the wood react with the protein under the accelerated heat and pressure conditions gained in the pressing cycle. This reaction also aids in accomplising the adhesive advantages of the protein.

The employment of the protein as the primary binder results in the formation, under the conditions of heat and pressure in the press, of a board having more desirable structural characteristics than wood-waste boards produced with a plastic as the primary binder.

From the foregoing description it will be apparent that I have conceived of an article of manufacture which will have the many advantages and will satisfy the objectives as set forth in the preamble to this specification.

While this specification sets forth the present and preferred details of the structural board and the method of manufacture thereof, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described the invention the following is claimed as new and useful, and upon which Letters Patent are desired:

1. A high density, dry-thermo pressed structural board including, as constituents, a woodwaste milled to predetermined particle size, a primary binder comprising a protein, and a substantially lesser amount of a resin binder; the wood-waste being present in a percentage greater than 80%, the protein binder being extracted flour of soya beans present in a percentage less than 10%, and the resin binder being melamineurea formaldehyde present within a range of 1 /2 and 1%.

2. A high density, dry-thermo pressed structural board comprised of the following in approximately the percentages stated: Reduced wood waste 90.40%, extracted flour of soya beans 5.00%, melamine-urea formaldehyde 1.00%, ammonium phosphate 1.25%; ammonium sulfate 1.25%, boric acid 375%, ethylene glycol .10%, and pentachlorphenate .25

3. A high density, dry-thermo pressed structural board comprised of the following in approximately the percentages stated: Reduced wood-waste 86.65%, extracted flour of soya beans 8.00%, melamine-urea formaldehyde 1.60%, am-

6 monium phosphate 1.25%, ammonium sulfate 1.25%, boric acid .'75%, ethylene glycol 10%, and pentachlorphenate .50

JOSEPH N. SEARS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,007,585 Satow July 9, 1935 2,034,522 Loetscher Mar. 1'7, 1936 2,038,113 Irey Apr. 21, 1936 2,143,413 Ellis Jan. 10, 1939 2,185,333 Denman Jan. 2, 1940 2,315,402 DAlelio Mar. 30, 1943 2,338,710 Dodge Jan. 11, 1944 2,368,660 Hochstetter Feb. 6, 1945 2,436,329 Porter Feb. 1'7, 1948 2,446,304 Roman Aug. 3, 1948 2,452,054 Jones et a1 Oct. 26, 1948 2,578,489 Roman Dec. 11, 1951 FOREIGN PATENTS Number Country Date 480,316 Great Britain Feb, 1'7, 1938 OTHER REFERENCES Winton, The Structure and Composition of Foods, vol. I, 1932 page 516.

Claims (1)

1. A HIGH DENSITY, DRY-THEREMO PRESSED STRUCTURAL BOARD INCLUDING, AS CONSTITUENTS, A WOODWASTE MILLED TO PREDETERMINED PARTICLE SIZE, A PRIMARY BINDER COMPRISING A PROTEIN, AND A SUBSTANTIALLY LESSER AMOUNT OF A RESIN BINDER; THE WOOD-WASTE BEING PRESENT IN A PERCENTAGE GREATER THAN 80%, THE PROTEIN BINDER BEING EXTRACTED FLOUR OF SOYA BEANS PRESENT INA PERCENTAGE LESS THAN 10%, AND THE RESIN BINDER BEING MELAMINEUREA FORMALDEHYDE PRESENT WITHIN A RANGE OF 1 1/2 AND 1%.