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Publication numberUS3196494 A
Publication typeGrant
Publication dateJul 27, 1965
Filing dateFeb 14, 1963
Priority dateFeb 14, 1963
Publication numberUS 3196494 A, US 3196494A, US-A-3196494, US3196494 A, US3196494A
InventorsHartman Seymour, Reuben F Hoffmann
Original AssigneeUs Plywood Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fire resistant door
US 3196494 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

y 1965 s. HARTMAN ETAL 3,196,494

FIRE RESISTANT DOOR Filed Feb. 4, 1963 3 F|RE RETARDANT TREATED SOFT MAPLE STILE 4 ASBESTOS-ELASTOMER CROSSBAND VENEER FIGURE l FIGURE 2 2 WELI JRQK MARINITE STILE II 3 FIRE REI'ARDANT TREATED SOFT MAPLE nae-.042 040 4 L" ABESTOS ELASTOMER 2e VENEER CROSSBAND Inventors SEYMOUR HARTMAN REUBEN F. HOFFMANN Attorney United States Patent 3,196,494 FIRE RESISTANT DOOR Seymour Hartman, Mahopac, N.Y., and Reuben F. Hodmann, Algoma, Wis., assignors to United States Plywood Corporation, New York, N.Y., a corporation of New York Filed Feb. 14, 1963, Ser. No. 258,396

5 Claims. (til. 20-45) The present invention is broadly concerned with building construction units and is particularly directed toward an improved type of fire resistant composite door, panel or similar structure. Thus, one object of the present invention is to provide a structural unit such as a door or panel which is practically fireproof, by being highly resistant to the destructive action of fire and extremely high temperatures. The door or panel or equivalent unit of the present invention is composed of a plurality of different materials, each of which functionsto raise the fire resistant characteristics of the unit as a whole to an extremely high level.

Another object of the present invention is to provide a composite door or panel of the type indicated which is highly resistant to leakage or the passage therethrough of hot gases, hot air, smoke or other vapors and which will not warp or bend when subjected to extremely high heat concentrated on one side of the door or panel. Other objects of the present invention are to provide a high type fireproof unit which is composed of materials which are of a very light weight and highly resistant to the transmission of heat therethrough.

In essence, the door or panel of the present invention comprises in combination a core, suitable stiles and rails, fire resistant cross bands comprising asbestos, fire resistant glue sheets and veneer facings.

The composite door or panel structure of the present invention is of such a nature that it will meet the Fire Underwriters Laboratory test described in ASTM E15256T Underwriters Laboratory Inc. for Fire Tests of Door Assemblies Pamphlet U.L. (b) 3rd edition.

In essence, the test requires the door to pass the code requirement for a 1 /2 hour fire door test. In this test, the door must be capable of withstanding, for 1 /2 hours, flames which cause a buildup in the temperature to 1790 F., on one face of the door. The temperature rise on the opposite face of the door during the first one-half hour must not exceed 250 F. above ambient temperature. At the end of this fire exposure test, the door must withstand the impact of a water hose stream at 30 lbs. pressure, which water hose stream is played on 0 the door from a distance of 20 feet for one minute and 47 seconds. As pointed out heretofore, the door or structure of the present invention is highly resistant to the leakage or transmission of high temperature heat which might ignite flammable materials which are located on the cold side of the structure.

It is to be noted that, at present, there exists no 1 /2 hour wood faced composite fire door. The only door which has a 1 /2 hour Underwriters label is a metal door. The composite door of the present invention is the first such door to pass the Underwriters test for a 1 /2 hour door. Thus, each component is interrelated and functions to produce a combined fire retardant 1 /2 hour composite fire door.


The door structure of the present invention may be readily appreciated by reference to the figures illustrating one embodiment of the same. FIGURE 1 is a plan view of the door with the facing plies thereof broken away in order to show the construction. FIGURE 2 is afragmentary cross-section view through the core and door.

Referring specifically to the figures, the core 1 of the door consists of a fireproof or non-burning inorganic material which has excellent heat insulating properties. A particularly desirable material for the core is Weldrok which is sold by United States Plywood; In general, this material should have a density in the range from about 18 to 24 lbs/cu. ft., preferably having a density in the range from 20 to 24 lbs/cu. ft. A particularly preferred type of material for the core is a calcium silicate subhydrate which is rendered porous by certain manufacturing steps.

In essence, the core material Weldrok consists of an incombustible mineral material consisting of complex metal silicates with fiber binder. Density of the core material can range from 18 to 24 lbs./ft. Weight/sq. ft. of this core material is 4 lbs. Weldrok is warp free and stable, and possesses a U factor of approximately"0.35 B.t.u./hr./sq. ft./ F.

The structural frame comprising stiles 2 and rails 6 are inorganic materials marketed by J ohns-Manville under the trade name Marinite. Since these materials are inorganic in nature, this type of structural frame prevents any burnout around the core material. Marinite is composed of an asbestos fiber, diatomaceous silica and an inorganic binder.

A fire retardant element 3 preferably a hard wood such as maple or hinge and lock blocks, composed of Marinite or treated maple, is positioned along the rails 6 and stiles 2. The A" fire retardant treated soft maple lumber is treated by the vacuum pressure cell process.

The crossbands 4 contribute greatly to the basic fireproofing composition and nature of the door of the present invention. These crossbands are of an asbestos neoprene composition and contribute greatly to the effectiveness of the door. The faces 5 of the door comprise lignocellular material, preferably veneer, and are laminated to the crossbands 4 with a phenolic impregnated adhesive. A preferred type is a precatalyzed phenolic powdered resin HP-401D, made by the Borden Chemical Company. Another satisfactory adhesive is Tego sold by Rohm and Haas. Tego is a B stage phenolic impregnated adhesive sheet which will cure under heat.

The dimensions of the panel or door may be varied appreciably depending upon its ultimate use. These dimensions are interrelated and depend upon the size and unit being fabricated. One satisfactory unit is to have the core of a thickness of from 1.5 86" to 1.594". .Under these conditions, the rails would approximate x 1.586 to 1.594" and the thickness of the crossband would approximate .038" to .042" thick. f

One typical group of dimensions are given in FIG- URE 2. It is to be noted that core 1 is keyed into stiles 2.

In order to further illustrate the invention, one technique for constructing the 1 /2 hour fire door is as follows:

(1) The core is made of Weldrok as manufactured by US. Plywood.

(2) The inner stiles and rails are made of Marinite- 36 lbs. density, /2 wide.

thermal expansion coeflicient. by the Underwriters Laboratories and has 'aflame spread (a) The Weldrok core are sized with a catalyzed urea formaldehyde resin'.

and Marinite stiles and rails .(3) Fire. retardant treated lumber outer'stiles and rails such as soft maple are jacent to the inner members. a

(4) The Weldrok core, innerMarinite stiles and rails and outer fire retardant treated wood stiles and rails are bonded together via the radio frequency bonding method.

14" wide and are used ad- (a) The adhesive can be either a'catalyzed urea-form aldehyde resin reinforced with a precatalyzed phenolic powdered resin HP-401D or a phenol-resorcinol adhesive resin.

surfaces to a uniform thickness of'approximately 1.586".

v (6) The assembly is then sized with a phenolic resin sizing formulation and semi-precured under an infra-red oven. The phenolic resin is similar to that which is manufactured by the Borden Chemical'Company.

(7) The: asbestos elastomer crossband is then sized and also semi-precured in the samemannen as the assembly. Y

The process fabrication steps for the unit areas follows:

(1) A veneer; face is placed on a platform.

. '(2) The previously sized. and. semi-precured asbestos crossband has a phenolic adhesive applied to both surfaces Which is then flashed off and semi-precured under an infra-red oven. 3 After immediate cooling,it is placed on the veneerface. I

(5) 7 After curing, this assembly is then sanded on both The sizing formulation is as follows: i 7 ,Pts. by wt. BR-LA- 1030 (Bakelite Co. Union Carbide & Co.) 30

. (BRLA+1 a slightly alkaline phenol formaldehyde resin of very low molecular weight to insure penetration in depth.)

H'l?40l*DBorden Chem. Co. so Methanol 60 'Tritdl'l X-l()0 (Rohrn & Haas) 0.2

(Triton X,-100 a nonionic wetting-agent) is isooctyl phenyl polyethoxy ethanol.) 7 A dry .preeatalyzed phenolic powdered resin glue.

i The purpose of thissizingis to penertate and seal the inorganic material such that when a compatible phenol vheat resistant resin is used for bonding, it will givebetter holding qualities and strength The' sizing formulation is comprised of'difierent 'phenol ingredients, plus an ad- 7 ditive to aid in penetration. This sizing is of a very light viscosity.-

' After the sizing material is applied, as then semiprecured in' theinfra-rjed oven at approximately 160 a for 35 seconds:

a The asbesto's elastomer crossband, which is approximately .038" to .042" thick 'is also phenolic sized and semi precure'd. This asbestos .cross'band material contributes much to the product for the coeflicients of linear (3) The previously sized unit or 'core fis then applied material. Y (4) Thesecond asbestos cros-sband has adhesive'applied to both surfaces, is curedand cooled' in the same to the other surface of the semi-precured "asbestos manner as the previous one and laid onthe'core assembly. 1

. -5) The second veneer faceis'applied to'the built-up construction.

' (6) The laid-up assembly is I pressed and ,cured via the hot plate process.

(7) After pressing, the 1 /2 hour 'fire door is then trimmed to tolerances, sanded, patched and inspected for imperfections.

. With respect to'the foregoing, the Weldrok corecomprises a material which is rated as .incombustible by the Underwriters Laboratory. -.It is very dimensionally stable and has a minimum compressive strength of about 550 lbs/sq. in. The" material is an excellent heatgins'ulatorfl and is easily machined. The lmaterial is. insoluble: in water. and'w'astested in accordance with standard test methods for fire hazard classification of building materials." a e The inorganic materialsjsuchas Marinite (36 pound) is manufactured by. Johns-Manville andis an.insulating material composed of asbestos fibers, diatomaceous silica It is fireproof and has a low' and an inorganic binder. I

This material was tested rating of 0. This material is used for the inner stiles and rails. I Thisftype of structural frame addsappreciably in preventing burnout around the core materials. 1 The-outer stiles and rails are composedof a fire rethe product;

process. a 7 'What isclairned is: v V

f- 1."A fire door comprisingacore composedv essentially expansion and contraction of the' various organic materials to render 'a better product, Not only does this help' withstand the rigor of the U.L. tests and the ASTM Specifications for the;fire and hose stream tests and applicatiombutfurther aids in dimensional stability of The phenolic adhesive used'for fabrication'is a phenolic type. similargto that produced by the: Borden Chemical The above mentioned phenol, adhesive mixture is applied to bothsurfaces :of the. asbestos crossband at a raterof approximately 35 poundsper thousand square feet 'of single glue line. It is :thenimmediately flashed off by means of a circulating air; and semi-precured under an infra-red oven at approximately 160 F. for 45 seconds.

Y The materialis then immediately cooled with cooling units and placed on the veneer faces. The entire laid-up assembly is then pressed and cured at180 pounds per square inch at 300 F1 for 10 minutes via the hot plate fof calcium silicate subhydrate, a peripheral frame. surrounding said calcium silicate subhydrate on allsidesto form a cbntinuous outside area, saidv peripheral frame tardant treated lumber. Thisis securedby means of. anr aqueous salt solution. .The soft maple. is .treated to refusal via the vacuum pressurefull cell process with a 7 method similar to the ProtexolClass .A{ treatment. This material was tested .in'accordance with ASTM E160-50 forcombustibility properties of ,treated woodf The. adhesive used to bond the Weldrok9core, inner and outer: stiles and rails can either be urea-formaldehyde 1 reinforced with a precatalyzed phenolic resin (HP-401D) or a phenol resorcinol adhesive resin; This is applied to one surface of the Marinite which is then placed against the-Weldrok core. The adhesive is also applied, to one surface of the treated lumber'and placed against the Marinite. ,This entire assembly is then cured, via

a dielectric method. 7 a

-mable decorative veneer is adhered to at least one'of .sa'id crossbands. p v 1 i 5,- ,Afire; door as set forthin claim-3 able to withstand composed essentially of asbestos fibers, diatomaceous earth and an inorganic binder, and a crossband on each side of said core composed essentially of an asbestos neoprenecomposition, andsaid crossbands extending over the entire core and frame'in a single plane direction.

2 A fire door as setforth in claim 1 wherein an untreat-ed, flammable vene'er'is adhered to at least one of said crossbands.

3.. A fire door as set forth in: claim 1 wherein an outer "frame surroundssaid peripheral frame of asbestos fibers,

diatomaceous earth and inorganic binder.

4. A'firedoor' as s'etforth in*claim 3"wherein a flama 1 /2 hour Underwriters Laboratories Fire Test,;wherein said outer frame is treated fire retardant: wood, and a flammable face i adhered to at least one of said cross bands which face comprises at least one ply of fibrous material.

References Cited by the Examiner UNITED STATES PATENTS 2,173,808 9/39 Kellogg 120-35 2,249,591 7/41 Allen 2035 2,534,814 12/50 DOlier 260-41.5 10 2,593,050 4/52 Paul et a1. 2035 2,751,366 6/56 Braenclle 26041.5

6 2,787,345 4/57 Soubier et a1. 18946 X 2,797,450 7/57 Ropel la 20-35 OTHER REFERENCES Underwriters Laboratories, Inc. Report on Composite Fire Doors For Owens Illinois Glass Co., Kaylo Division, Toledo, Ohio, Retardant No. 3221, Feb. 20, 1950, National Board of Fire Underwriters, 2 07 East Ohio St., Chicago, Illinois.

FRANK L. ABBOTT, Primary Examiner.


Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2173808 *Dec 12, 1935Sep 19, 1939Johns ManvilleStructural unit
US2249591 *Feb 11, 1941Jul 15, 1941Peele CompanyFire door
US2534814 *Aug 7, 1948Dec 19, 1950Raybestos Manhattan IncProduction of asbestos-rubber compositions
US2593050 *Jan 24, 1952Apr 15, 1952Owens Illinois Glass CoComposite fire door
US2751366 *May 9, 1952Jun 19, 1956Du PontRubbers with methoxy containing silica fillers
US2787345 *Nov 19, 1952Apr 2, 1957Owens Illinois Glass CoFire resistant structural units
US2797450 *Aug 12, 1955Jul 2, 1957Roddis Plywood CorpFireproof door construction
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3274734 *Sep 21, 1964Sep 27, 1966Padde Pty LtdFire resistant door
US3462339 *Mar 15, 1966Aug 19, 1969Koppers Co IncFire-retardant panel construction
US3480494 *Feb 11, 1966Nov 25, 1969R S Bacon Veneer CoMethod of forming fire retardant panels
US3635784 *Mar 16, 1967Jan 18, 1972Snitker Jens CSolid composite boards having a compact core of adhesive binder and 85{14 98 percent by volume of porous, nonabsorbing granulates selected from the group consisting of cork bark, and vermiculite
US3994110 *Apr 10, 1975Nov 30, 1976Champion International CorporationThree hour fire resistant door, panel or building element, and method of manufacturing the same
US3998023 *Aug 4, 1975Dec 21, 1976H. H. Robertson CompanyDouble-skin insulated building panel
US3998024 *Aug 4, 1975Dec 21, 1976H. H. Robertson CompanyDouble-skin insulated building panel
US4104828 *May 26, 1977Aug 8, 1978Cal-Wood DoorSolid door having edges of laminated pressed wood fiber sheet material
US4256798 *Dec 5, 1978Mar 17, 1981Permagrain Products, Inc.Moisture-resistant fire-retardant decorative floor and wall coverings and process for the manufacture thereof
US4343127 *Jan 15, 1981Aug 10, 1982Georgia-Pacific CorporationFire door
US4748771 *Jul 30, 1985Jun 7, 1988Georgia-Pacific CorporationFire door
US4811538 *Oct 20, 1987Mar 14, 1989Georgia-Pacific CorporationFire-resistant door
US8037820Mar 29, 2007Oct 18, 2011William DanielsDecorative, wood fire-rated door and method
US8691340Dec 30, 2009Apr 8, 2014Apinee, Inc.Preservation of wood, compositions and methods thereof
US9314938Feb 10, 2014Apr 19, 2016Apinee, Inc.Preservation of wood, compositions and methods thereof
US9422765Jun 6, 2014Aug 23, 2016Recor International, Inc.Method for making flush architectural doors using post-consumer materials
US20030033786 *Aug 17, 2001Feb 20, 2003Leon YulkowskiFire door assembly
US20070245661 *Mar 29, 2007Oct 25, 2007William DanielsDecorative, wood fire-rated door and method
US20120272616 *Apr 29, 2011Nov 1, 2012Lucas Iii William HenrySystems and methods for making flush architectural doors using post-consumer materials
EP1555378A2 *Dec 20, 2004Jul 20, 2005Schörghuber Spezialtüren GmbH & Co. Betriebs-KGFire-proof door
EP1555378A3 *Dec 20, 2004Apr 2, 2008Schörghuber Spezialtüren GmbH & Co. Betriebs-KGFire-proof door
U.S. Classification428/50, 428/443, 428/141, 428/920, 428/70, 428/921
International ClassificationE06B5/16
Cooperative ClassificationE06B2003/7059, E06B2003/7051, Y10S428/92, E06B5/16, E06B3/822, E06B2003/7025, Y10S428/921, E06B2003/7063
European ClassificationE06B5/16