# US 6,773,639 B2 · Method of and system for forming a fire door core

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- Number: US 6,773,639 B2
- Document ID: US6773639B2
- Status: Granted
- Kind: B2
- Application number: 09/973,086
- Filed: 2001-10-10
- Published: 2002-08-01
- Granted: 2004-08-10
- Earliest claimed: 2000-10-12
- Assignees: Premdor International, Inc.
- Inventors: Hartley Moyes; Michael Windsor Symons
- Web page: https://patentgrep.com/patent/US6773639B2

## CPC

- C04B 28/145: {Calcium sulfate hemi-hydrate with a specific crystal form}
- B29C 43/003: {characterised by the choice of material}
- B29C 43/02: of articles of definite length, i.e. discrete articles {(B29C35/0227 takes precedence)}
- C04B 28/02: containing hydraulic cements other than calcium sulfates
- B29C 31/08: of preforms {to be moulded, e.g. tablets, fibre reinforced preforms, extruded ribbons, tubes or profiles; Manipulating means specially adapted for feeding preforms, e.g. supports conveyors (B29C31/066, B29C37/001, B29C43/085 take precedence)}
- B29C 33/56: Coatings {, e.g. enameled or galvanised}; Releasing, lubricating or separating agents {(in-mould coating B29C37/0028; using or applying separating agents B29C37/0067)}
- B29C 43/50: Removing moulded articles
- B29K 2105/0872: {Prepregs}
- B29K 2105/251: {Particles, powder or granules (expandable particles B29K2105/046)}
- B29K 2311/14: Wood, e.g. woodboard or fibreboard
- B29L 2031/724: {Doors}
- C04B 2111/28: Fire resistance, i.e. materials resistant to accidental fires or high temperatures
- E06B 5/164: {Sealing arrangements between the door or window and its frame, e.g. intumescent seals specially adapted therefor}
- Y10T 29/49623: Static structure, e.g., a building component
- Y10T 29/49629: Panel
- Y10T 428/249973: Mineral element
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- E06B: FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES (shades or blinds for greenhouses A01G9/22; curtains A47H; lids for car boots or bonnets B62D25/10; skylights E04B7/18; sunshades, awnings E04F10/00)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method and system of forming a fire door core. Hydraulic binder and resin are supplied from raw material bins and mixed to provide a submixture. Exfoliated vermiculite is then mixed with the submixture to provide a mixture that is deposited into a plurality of compression molds. Each of the filled molds are pressed in a press at a predetermined temperature at a predetermined pressure for a predetermined period of time sufficient to harden the mixture into a hardened slab. The hardened slabs are then removed from the molds, impregnated with water or steam in a water impregnation assembly and dried in a drying assembly.

## Claims

### Claim 1

A method of forming fire door components of resin bonded vermiculate and hydraulic binder, comprising the steps of:
a) depositing into a mold a mixture of exfoliated vermiculite, a resin and a hydraulic binder, the mold being maintained at a temperature less than the reaction temperature of the resin;
b) transferring the mold and thereby the mixture to a heated press;
c) applying to the mixture through the press a predetermined pressure at a predetermined temperature for a predetermined period sufficient to harden the mixture into a fire door core having a density from about 350 kg/m3 to about 600 kg/m3; and
d) removing the hardened fire door core from the mold.

### Claim 2 (depends on 1)

The method of claim 1, including the step of:
a) providing up to 10% by weight of the exfoliated vermiculite from recycled vermiculite materials.

### Claim 3 (depends on 1)

The method of forming fire door components of resin bonded vermiculite and hydraulic binder as in claim 1, further comprising the steps of:
a) depositing into a second mold a second mixture of exfoliated vermiculite, a resin and a hydraulic binder, the second mold being maintained at a temperature less than the reaction temperature of the resin;
b) transferring the second mold and thereby the second mixture to the heated press; and
c) applying substantially 800-1200 p.s.i. pressure to the second mixture in the second mold in the press and thereby forming a hardened slab having a density of from about 900 to about 1,300 kg/m3.

### Claim 4 (depends on 3)

The method of forming for a door compartment of resin bonded vermiculite and hydraulic binder as in claim 3, further comprising the step of:
a) reducing the hardened slab into at least first and second strips for fire door support structures.

### Claim 5

A method of forming a fire door core, comprising the steps of:
a) depositing into a mold a mixture of exfoliated vermiculite, a resin and a hydraulic binder;
b) controlling a temperature of the mold such that the mold is maintained at a temperature less than the reaction temperature of the resin;
c) transferring the mold and thereby the mixture to a heated press;
d) applying to the mixture through the press a predetermined pressure at a predetermined temperature for a predetermined period sufficient to harden the mixture into a fire retardant fire door core having basic properties meeting industry-wide fire endurance tests; and
e) removing the hardened fire retardant fire door core from the mold;
wherein the hardened fire retardant fire door core has good integrity and dimensional stability when exposed to fire temperatures.

### Claim 6 (depends on 5)

The method of forming a fire door core as in claim 5, wherein the mold is preheated.

### Claim 7 (depends on 6)

The method of forming a fire door core as in claim 6, wherein the mold is pre-heated to a temperature of less than 125° C.

### Claim 8 (depends on 5)

The method of forming a fire door core as in claim 5, further comprising the steps of:
a) providing door stiles and door rails comprised of exfoliated vermiculite, said door stiles and door rails having a higher density than said fire retardant fire door core;
b) affixing said fire retardant fire core door to said door stiles and door rails.

### Claim 9 (depends on 5)

The method of forming a fire door core as in claim 5, including the step of:
a) selecting the resin from the group consisting of novolac resins, and selecting the hydraulic binder from the group consisting of gypsum, synthetic gypsum, hydrated gypsum, Portland cement, high alumina cement, gypsum cement, α-calcium sulphate hemihydrate, β-calcium sulphate hemihydrate, magnesium oxychloride, magnesium oxysulphate, calcium sulphoaluminate cement, an alkali silicate, ground granulated blast furnace slag, and mixtures of any two or more of the foregoing.

### Claim 10 (depends on 9)

The method of forming a fire door core as in claim 9, including the step of:
a) providing sufficient vermiculite to achieve a mixture having from about 50% by weight to about 85% by weight vermiculite.

### Claim 11 (depends on 9)

The method of forming a fire door core as in claim 9, including the step of:
a) blending fibers in the mixture.

### Claim 12 (depends on 11)

The method of forming a fire door core as in claim 11, including the step of:
a) selecting the fibers from the group consisting of glass fibers, chopped strand glass fibers, inorganic fibers, and Dralon fibers.

### Claim 13 (depends on 5)

The method of forming a fire door core as in claim 5, including the step of:
a) forming the mixture by mixing the hydraulic binder and resin into a submixture and mixing the submixture with the exfoliated vermiculite.

### Claim 14 (depends on 13)

The method of forming a fire door core as in claim 13, including the step of:
a) forming the mixture from about 20% by weight to about 40% by weight hydraulic binder, from about 5% by weight to about 15% by weight resin, and with the balance being vermiculite.

### Claim 15 (depends on 13)

The method of forming a fire door core as in claim 13, including the step of:
a) blending the vermiculite and submixture gently prior to depositing the mixture into the mold.

### Claim 16 (depends on 13)

The method of forming a fire door core as in claim 13, including the step of:
a) adding a release agent to the submixture, the release agent being from about 1% by weight of the resin bonded exfoliated vermiculite mixture.

### Claim 17 (depends on 13)

The method of forming a fire door core as in claim 13, including the step of:
a) applying a surface release agent to the mold.

### Claim 18 (depends on 5)

The method of forming a fire door core as in claim 5, including the step of:
a) maintaining the mold at a temperature less than the reaction temperature of the resin while the mixture is being deposited into the mold.

### Claim 19 (depends on 18)

The method of forming a fire door core as in claim 18, including the step of:
a) applying substantially 150-1200 p.s.i. pressure to the mixture in the mold through the press.

### Claim 20 (depends on 19)

The method of forming a fire door core as in claim 19, including the step of:
a) applying from about 150 to about 400 p.s.i. pressure and thereby forming a low density core.

### Claim 21 (depends on 19)

The method of forming a fire door as in claim 19, including the step of:
a) applying from about 800 to about 1200 p.s.i. pressure and thereby forming a core having a density of from about 900 to about 1,300 kg/m3.

### Claim 22 (depends on 19)

The method of forming a fire door core as in claim 19, including the step of:
a) heating the mixture to a temperature above the reaction temperature of the resin for a period sufficient to react the resin and harden the mixture into the core.

### Claim 23 (depends on 22)

The method of forming a fire door core as in claim 22, including the step of:
a) maintaining the mixture in the mold at a temperature less than the resin curing temperature prior to placing the mold in the press.

### Claim 24 (depends on 5)

The method of forming a fire door core as in claim 5, including the step of:
a) impregnating the core by immersion in water or absorption by steam.

### Claim 25 (depends on 24)

The method of forming a fire door core as in claim 24, including the step of:
a) applying a vacuum to the core before it is immersed in the water.

### Claim 26 (depends on 24)

The method of forming a fire door core as in claim 24, wherein:
a) the core has a density from about 350 kg/m3 to about 600 kg/m3.

### Claim 27 (depends on 24)

The method of forming a fire door core as in claim 24, including the step of:
a) immersing the core in the water or allowing the core to absorb steam for a period sufficient to hydrate the hydraulic binder.

### Claim 28 (depends on 27)

The method of forming a fire door core as in claim 27, including the step of:
a) providing hemi-hydrated gypsum as the hydraulic binder, and immersing the core for a period sufficient to convert the hemi-hydrated gypsum to hydrated gypsum.

### Claim 29 (depends on 28)

The method of forming a fire door core as in claim 28, including the step of:
a) drying the core to a moisture content of from about 10% to about 14% by weight water.

### Claim 30 (depends on 29)

The method of forming a fire door core as in claim 29, including the step of:
a) maintaining the gypsum as hydrated gypsum.

### Claim 31

A fire retardant fire door core forming system, comprising:
a) a plurality of raw material sources for storing raw materials including exfoliated vermiculite, resin, and hydraulic binder;
b) a mixing system, said mixing system in communication with said raw material sources, said mixing system comprising a first mixing assembly for combining said resin and said hydraulic binder to create a submixture and a second mixing assembly in communication with said first mixing assembly for combining said submixture with said exfoliated vermiculite to create a final mixture;
c) a plurality of molds, each mold in operative communication with said second mixing assembly for receiving a predetermined supply of said final mixture of said raw materials from said second mixing assembly thereby providing a plurality of filled molds;
d) a vibratory assembly for receiving each of said filled molds and for causing said final mixture of said raw materials in said filled molds to achieve a substantially uniform density in each of the associated filled and vibrated molds; and
e) a heated press in operative association with said vibratory assembly for receiving the filled and vibrated molds and for applying sufficient heat and pressure for a sufficient period to cause said final mixture of said raw materials in each of said filled and vibrated molds to form fire retardant fire door cores having a hardened state.

### Claim 32 (depends on 31)

The system of claim 31, further comprising:
a) a water impregnation assembly operatively associated with said press for impregnating the hardened cores with water or steam; and
b) a drying assembly operatively associated with said water impregnation assembly for drying the cores to a predetermined moisture content.