US2825660A

US2825660A - Waterproof fiberboard

Info

Publication number: US2825660A
Application number: US478910A
Authority: US
Inventors: Henry J Roux
Original assignee: Armstrong Cork Co
Current assignee: Armstrong World Industries Inc
Priority date: 1954-12-30
Filing date: 1954-12-30
Publication date: 1958-03-04
Anticipated expiration: 1975-03-04

Description

March 4, 1958 H. J. ROUX 2,825,660

WATERPROOF FlBERBOARD Filed Dec. 50, 1954 ASPHALT RUBBER-ALGNATE COATI N G F IBERBOARD INVENTOR HENRY J. ROUX ATTORNEY United States Patent WATERPROOFFIBERBOARD Henry J. Roux, Lancaster, 'Pa., .assignor to Armstrong Cork Company, Lancaster, Pa., a Corporation of Pennsylvania Application December30, 1954, Serial No. 478,910

2 Claims. (Cl. 117-1355) This invention relates to awaterproof, vapor-permeable insulation board and method of producing the same, and

more particularly to a conventional "fiberboard insulation product having applied thereto a film of coating material which will resist the penetration of water into the board .ing the outer walls of the building. This sheathing-is usually in place for a period of timebefore the-exterior finishof the building is put in place over the sheathing.

During this period of time,the sheathing is exposed to the weather; and if the material is not 'weatherproofed, the

insulationbeco'mes waterlogged and the insulating value is greatly diminished. In order to overcome this, it has been common practice to apply a film of asphalt to the surface of the sheathing material. This film of asphalt is Waterproof and renders the sheathing resistant to rain when exposed to the elements; however, the asphalt coating is also vapor-impermeable, and thereby prevents the passage of moisture from the interior of the building through the insulating material to the outside of the building. This waterproof coating is applied to the outside of the insulating sheathing and, therefore, forms a vapor barrier at the outer surface of the sheathing, which means that the moisture condenses in the sheathing, thereby diminishing its insulating value. This has been overcome to a certain extent by applying a relatively hard asphalt coating, and depending on the heavy brittle coating, cracking upon drying, leaving small fissures through which moisture can escape. This is a rather haphazard arrangement, however, and the transmission of vapor through the fiberboard is diminished somewhat by this type of coating.

The invention set forth in this application is directed to a fiberboard material in which a film of asphalt emulsion and rubber latex, together with an alginate, is applied to the surface of the insulating board at the time the board is produced on a conventional Web-forming fiberboard machine. This film of asphalt emulsion and rubber latex with the alginate renders the fiberboard resistant to water from the elements but renders the surface of the board vapor-permeable so that moisture transmitted from the interior of the building can pass freely through the fiberboard to the exterior. As a matter of fact, the transmission of the vapor through the board is not diminished to any appreciable extent because of the coating.

An object of this invention is to provide an insulating sheathing having applied thereto a waterproof, vaporpermeable coating which will render the insulation resistant to waterlogging caused from exterior water and will at the same time render the board vapor-permeable to permit the ready transmission of vapor through the board.

Another object of this invention is to provide a method acoating for theasphalt particles. =aidsin'renclering the coating water repellent.

2,825,650 Patented Mar. 4, 1958 ofproducingsa fiberboard with a waterproof, vapor-permeable coating by the application of a coating comprisingiasphalt emulsion, rubber latex, and an alginate'at the wetend of the fiberboard forming machine.

In .carryingout the invention, it has been foundthat soap type asphalt emulsion is best suited for producing the desired results. The rubber latex may be any of the conventional synthetic or natural rubber latices and the alginate .may be any of the conventional commercially available alginates,'such as, for example, Keltex, which is a sodium :derivative of-algin and is one of the complex organic alginates.

I have rfound'that. a suitable formulation for carrying out the invention is as follows:

Dow latex 512K (60% styrene and 40% butadiene)- 25 -Keltex (sodium derivative of alginate) 1.5

Dowicide G (sodium. salt of pentachlorophenol)--- 0.2

In-theabove formulation, the asphalt emulsion, which .forms .a major proportion of the coating, renders the coating water resistant and also helps to adhere the coat- .ingto the fiberboard. The latex 512K, which is a copolyruercomprising 60% styrene and 40% butadiene, forms The rubber latex also While-in the examplegiven the rubber latex is a: styrene-butadiene type latex, it will beunderstood that; any of the conven- .tional.syn thetic rubber latices or natural rubber latices are suitable for carrying out the invention. Therubber latex should be present in a quantity sufficient to coat the asphalt particles. The preferred range of rubber latex to asphalt emulsion has been found to be between .05 to .3 rubber latex compared to the quantity of asphalt emulsion used.

The Keltex, which is a sodium derivative complex organic alginate, serves as a web for adhering the latex coated asphalt particles together. This forms a coating which is smooth but not continuous because of the extremely small interstices distributed uniformly therethrough. These interstices are of such a nature that the water coming in contact with the exterior of the board will not penetrate the board through the interstices but the interstices permit vapor to pass therethrough as vapor pressure is built up in the board caused by vapor pressure differentials between the interior and the exterior of the board. For best results, the Keltex should be present in an amount ranging from .005 part to one part of asphalt emulsion to .01 part to one part of asphalt emulsion. The Dowicide G, which is a sodium salt of pentachlorophenol, is present as a preservative for the Keltex and the rubber latex. Any of the conventional preservatives for rubber latex are suitable for carrying out this purpose.

The attached drawing illustrates a piece of fiberboard with the waterproof vapor-permeable coating applied thereto.

In the application of the coating to the fiberboard, it has been found that the most expeditious way to apply the coating is to apply it at the wet end of the boardforming machine. When this is done, both the coating and the board can be dried simultaneously by one passage through the drier. If the coating is applied after the board has been formed and dried, it is necessary to utilize hot melt equipment on the application of a coating of asphalt to the surface of the board. The above coating could be applied to the dry board; however, an additional drying step would be involved and considerable assumes time and expense can be saved if the coating is appliedat. a

the wet end of the board-forming machine. 7 In the application of coatings at the wet end of the board-forming"process,; the problem: of diffusioncof the coating material through'ithe wet board is of considerable importance; Most coatings'appliedarthe wet end'diifus'e freely through the board and coat the:fibers substantially :uniformly throughout the board.thickness;' \Thisiis a 2.

' .place because of the web structure which is formedby the 'alginate adheringcthe' rubber-coated iasphaltt'pa'rticles to one another. This weblike structure prevents undueidiffusion :into the board and the-coating;is merely .applied to the surface of the wet board; 1 5i if? The coating is preferably applied to the wet board from a pool which is disposed back of a roller which engages :the surface of the board with a slight amount of pressure. Thewet board moves'through under the reservoir of coating material and the excess coating material-is removed by means of the roller which appliesa slight amount of pressure to the surface of the wet board. After the board .moves beyond the point at which the roller applies pressure, the board springs back to its original thickness and the thin film of coatin'g'mater'ial is applied uniformly to --the surface of the boards This-is only one of the many 'systems which may be utilized for the application'of the coating composition to the board at the wet end of-the board-forming machine; It will be-unde rsto od that the coating material could be sprayed directly'onto the finishedweb as it moves between'the forming machine and the drier, andcalso the coating may be applied by means of a printing device coming in contact with the surface of the newly formed board ash is mov' g between the forming machine and the drier. r

As, the. board is removedrfrom the .dryingcequipment; 7

the surface is coated witha thin film of black coating material which renders the board waterproof; however, the coating does not diminish the transmission of vapor through theboard to any appreciable extent.

Iclaim: i s. 2 1

1. As an article of manufacture, an insulation board composed of matted and entangled fibers, said board having a normal heat insulatingyalue and a coating adhering to saidrboard to 'render said board waterproof and vapor-permeable without material difiusion of the coating into the interior of said board so as to alter substantially its normal heatiinsula'ting value and vapor permeability, said coating comprising amixture of asphalt, rubber, and a water-soluble alginate.

2. As an article of manufacture, an insulation board composed of matted and entangled fibers, said board having a normal heat'insulating value and.;a coatin'gadherving to said board tosrender said board waterproof and vapor-permeable withoutmaterial diffusion into the interior of'said board soasinot to alter substantially its normal heat insulating value and vapor permeability,'fsaid coating'comprisinga mixture of parts asphalt,-10 to I .30parts rubberyand 05 m2 parts of a, water-soluble alginate.

Referenc es'Cited -in-the file of this patent UNITED STATES PATENTS Erdahl May '9, 1922 I 2,105,825 Smith Jan. 13,1933 7 2,210,348 Swope Aug. 6, 1940 2,393,022 Jan. 15,1946 2,701,219 Fair Feb. 1, 1955 Christensen Apr. 2, .1957

Claims

1. AS AN ARTICLE OF MANUFACTURE, AN INSULATION BOARD COMPOSED OF MATTED AND ENTANGLED FIBERS, SAID BOARD HAVING A NORMAL HEAT INSULATING VALUE AND A COATING ADHERING TO SAID BOARD TO RENDER SAID BOARD WATREPROOF AND VAPOR-PERMEABLE WITHOUT MATERIAL DIFFUSION OF THE COATING INTO THE INTERIOR OF SAID BOARD SO AS TO ALTER SUBSTANTIALLY ITS NORMAL HEAT INSULATING VALUE AND VAPOR PERMEABILITY, SAID COATING COMPRISING A MIXTURE OF ASPHALT, RUBBER, AND A WATER-SOLUBLE ALIGNATE.