US 3704197 A
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Description (OCR text may contain errors)
NOV. 28, 1972 J BAHLQ 3,704,197
REMOVABLE FLOOR COVERING Filed April 5, 1971 2 Sheets-Sheet 1 FIG. I
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Nov. 28, 1972 J. F. BAHLO 3,704,197
REMOVABLE FLOOR COVERING Filed April 5, 1971 2 Sheets-Sheet z 0 l8 f v (M INVENTOR JURGEN F BAHLO ATTORNEYS.
United States Patent 3,704,197 REMOVABLE FLOOR COVERING Jurgen F. Bahlo, Cherry Hill, N.J.., assignor to General Felt Industries, Inc., Saddle Brook, NJ. Filed Apr. 5, 1971, Ser. No. 131,019 Int. Cl. B32b 3/06, 7/14 U.S. Cl. 161-67 14 Claims ABSTRACT OF THE DISCLOSURE An adhesive backed removable carpet tile comprising a foam backing and a carpet layer is disclosed which may be applied to a subfloor and subsequently removed therefrom without delaminating the foam backing. The adhesive provides a release strength lower than the delamination strength of the foam backing. To provide the proper release strength, the adhesive is applied to the foam backing by a figurated roller to cover between and 50 percent of the foam backing.
BACKGROUND OF THE INVENTION Adhesive backed floor coverings are well known in the prior art. Vinyl surfaced tiles having an adhesive backing may be applied to a subfloor and subsequently removed therefrom without difliculty. Many carpet surfaced tiles provided by the prior art which are adhesively secured to a subfioor cannot be readily removed since the carpet layer delaminates from the foam backing thereby leaving the foam backing secured to the subfloor. The foam backing must then be removed, usually by scraping, using solvents and the like, which is an onerous task.
The problem of removing adhesive backed carpet tiles is particularly acute since the laying of indoor-outdoor type carpet tiles has become a popular do-it-yourself means of redecorating a dwelling. The need for removing previously laid adhesive backed carpet tiles normally occurs in two situations. The first is where the consumer is unsatisfied with his results in laying the tiles and desires to remove part or all of the tiles to correct a small error in laying. With the carpet tiles of the prior art, the consumer will succeed only in destroying the tiles he attempts to remove. If the consumer persists in correcting his errors, he will compound his difficulties and necessitate the expenditure of greater amounts of time, effort and money to provide a satisfactory floor covering. Under these circumstances, the possibility of a repeat sale is lost.
The second situation where it is necessary or desirable to remove previously laid adhesive backed carpet tiles is where the tiles have been in place for some length of time and begin to show wear. As the consumer attempts to remove the worn tiles, the tiles delaminate thereupon requiring considerable effort to clean the subfloor in preparation for laying new tiles. In this situation also, the possibilities of repeat sales evaporate.
In the prior art, pressure sensitive adhesive has been applied to foam-rubber backed carpet tiles by knife coating, kiss-roller coating, overall engraved print roller coating and by spraying. Application by knife coating or kiss-roller coating provides an uneven adhesive application whenever the foam backing has a physically nonuniform surface. Accordingly, the prior art carpet tiles manufactured by these processes exhibit uneven release strengths whereby the tile delaminates upon removal. Application of adhesive by overall engraved print rollers or by spraying causes varying amounts of adhesive to be absorbed by foam backing of differing cell structures. The release strength of the adhesive cannot be duplicated from one batch of carpet to the next since the foam cell structures usually differ significantly.
SUMMARY OF THE INVENTION It is an object of this invention to provide a floor covering comprising a foam backing adhesively securable to a subfloor and removable without delaminating the floor covering.
Another object of the invention is to provide an adhesively securable foam backed carpet tile in which the release strength of the adhesive is less than the delamination strength of the tile.
In summary, the floor covering of this invention comprises a foam backing having a given tear strength, a traffic bearing layer bonded to the backing, and adhesive means on the backing for securing the tile to an underlying surface and for removing the tile therefrom without tearing the backing, the adhesive means comprising a multiplicity of discrete portions of adhesive material having a tack level in excess of the tear strength of the backing, the discrete portions having an area of less than about .01 square inch each and aggregating less than about 50 percent of the area of the backing.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of the back of a carpet tile made in accordance with this invention;
FIG. 2 is a side elevation of the carpet tile of FIG. 1;
FIG. 3 is an enlarged view of part of the back of the carpet tile of FIGS. 1 and 2;
FIG. 4 is an enlarged cross sectional view of the carpet tile of FIG. 3 taken substantially along line 44 thereof as viewed in the directions shown by the arrows;
FIG. 5 illustrates a prior art adhesive backed carpet tile during removal thereof from a subfloor; and
FIG. 6 illustraes a carpet tile of this invention during removal from a subfioor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1-3 there is shown a floor covering 10 having a foam backing 12 and a traflic bearing layer 14. The foam backing 12 has thereon adhesive means 16 for securing the floor covering 10 to a subfioor.
The foam backing 12 and the traflic bearing layer 14 are made in any suitable manner. The trafiic bearing layer 14 comprises carpeting of any suitable type and includes a. multiplicity of fibers 18, such as fibers or yarns, as shown in FIG. 4. Typically the carpeting 14 is first manufactured and the foam backing 12, usually comprising a styrenebutadiene rubber, is cast thereon as a liquid. The liquid rapidly sets into a foam material bonded to the carpeting 14. The bulk density of the foam backing 12 varies between '8.5 and 19 pounds/ cubic foot, typically and weighs about 14.75 pounds/cubic foot. The tear strength of the foam backing 12 is between 1 and 2.25 pounds/linear inch with typical values lying in the lower part of this range.
One of the difiiculties encountered in providing an adhesive backed carpet tile which may be removed without delamination resides in the variation in cell structure and porosity of the foam backing 12. As will be appreciated by those skilled in the art, the porosity and the cell structure of the backing 12 varies substantially from day to day depending on the latex shelf age, composition and/or the environmental conditions under which the liquid rubber is cast onto the carpeting 14. With high porosity, the foam backing 12 tends to absorb increased amounts of adhesive thereby increasing the strength of the bond between the carpet tile and the subfioor. When the release level of this bond exceeds the tear strength of the foam backing, the floor covering delaminates upon attempted removal from the subfloor.
A very desirable adhesive material for securing a floor covering to a subfloor is a water dispersed acrylic adhesive. If this adhesive is applied over the total of the foam backing 12, at for example .002 inch thickness, the release strength of the dried and cured adhesive exceeds the tear strength of the backing 12 whereupon the floor covering 10 delaminates during the removal. On the other hand it is desirable for the adhesive to be spread over the entire part of the backing to prevent edge curling and slippage.
In accordance with this invention, the adhesive means 16 comprises an adhesive material having a tack level in excess of the minimum tear strength of the foam backing 12 and desirably in the range of 1.25-1.75 pounds/inch when applied in a film .001 inch thick. The adhesive material is preferably a water-dispersed acrylic adhesive such as may be obtained from Manufacturers Chemical Company, Camden, NJ. under the trade name Manuflex 3015. This adhesive typically has a tack level of about 1.3 pounds/inch at .001 inch thickness of film application. To provide a satisfactory release strength so that the floor covering 10' may be removed from a subfloor without delaminating, the adhesive material is applied to the backing 12 in a multiplicity of discrete portions 20 as shown best in FIGS. 3 and 4. Each of the portions 20 is desirably less than about 0.1 square inch in extent and is preferably between .001 and .002 square inch in area. The adhesive portions 20 are preferably between .015 and .02 inch in depth. As will be appreciated, the larger each of the portions 20 becomes the greater is the possibility for localized tearing of the backing 12 which tends toward general delamination. As will be more fully apparent hereinafter, the individual portions 20 are conveniently circular having a diameter between .04 and .05 inch.
The area of the backing 12 covered by the adhesive portions 20 desirably comprises between 10 and 50 percent thereof. Instead of distributing the adhesive portions 20 evenly over the backing 12, better release strength are obtained by disposing the portions 20 in groups or sets which are spaced apart by areas aggregating approximately 30 percent of the backing 12. The area of each set covered by the adhesive portions 20 may be up to 80 percent provided the sets are small. In the embodiment illustrated in FIGS. 1 and 3, the adhesive portions 20 aggregate approximately 30 percent of the area of each adhesive set and aggregate approximately 11 percent of the area of the backing 12.
As shown best in FIGS. 1 and 3, the adhesive portions 20 are preferably arranged in sets of diamond or parallelogram configuration having a long axis 22 and a substantially perpendicular short axis 24 in order to debond the minimum number of portions 20 at any given time. The long axis 22 of the sets located in each quadrant of the carpet tile 10 are parallel to a line 26 extending from the corner and the center of the backing 12. The normal manner in which a tile is removed from a subfloor is to peel back one corner thereof as suggested in FIGS. and 6. Orienting the long axis 22 of the adhesive sets in the manner shown in FIGS. 1 and 3 insures a minimum number of discrete portions 20 being debonded from the subfloor at all times during the removal operation.
It is essential that the release strength of the adhesive means 16 be less than the tear strength of the foam backing 12. Using a foam backing having a tear strength between 1.0 and 2.25 pounds/inch the maximum release strength of the adhesive means 16 is between .6 and .9 pound/inch. The minimum release strength of the adhesive means 16 must be sufficient to adhere the carpet tiles to a subfloor and desirably is between .1 and .5 pound/inch.
Typical carpet layers 14 have a grain direction that must be aligned when the tiles 10 are placed to insure a uniform appearance. It is common in the prior art to print an arrow on the foam backing 12 to indicate the grain direction of the carpet layer 14. In the prior art, this necessarily involves a separate or complicated printing operation since the adhesives of the prior art are applied over substantially all of the backing 12. An advantageous side light of this invention may be taken advantage of where the adhesive material visibly contrasts with the foam backing 12. As shown in FIG. 1, some of the adhesive portions 20 are arranged to describe an arrow corresponding to the grain direction in the carpet layer 14. The arrows 28 are, of course, applied to the backing 12 simultaneously with the application of the remainder of the adhesive portions 20. When using this invention, the eifort expended in separately printing a grain directing arrow on the foam backing 12 may be omitted.
In the process of this invention, the adhesive material is applied to the foam backing 12 with a design figurated roller having a multiplicity of circular cups formed therein to receive the adhesive material from a container and transfer it to the backing 1.2. The cups and the roller are conveniently circular for convenience in making the roller. The cups are preferably between .04 and .05 inch in diameter and are between .015 and .02 inch in depth. Another reason for making the adhesive portions 20 small is the difficulty in applying adhesive material in larger areas.
As a specific example, carpet tiles presently made by the assignee were removed from the production line. The foam backing thereof had a bulk density of 14.75 pounds/ cubic foot and a delamination strength of about 1.0 pound/inch. The tiles were placed in a roller type printing machine wherein the roller had been engraved with a multiplicity of .045 inch diameter x .015 inch deep cups disposed in a pattern reverse of that shown in FIG. 1. The area of the cups in each set aggregated approximately 30 percent of the area thereof. The aggregate area of the cups comprised approximately 11 percent of the area of the 12 inch x 12 inch carpet tile. Manuflex 3015 adhesive having a tack level of 600 grams/inch for a .001 inch dry film from Manufacturers Chemical Company was placed in the receptacle of the printing machine. The engraved configurated roller dipped into the receptacle and picked up a substantial amount of adhesive material. A doctor blade was used to remove excess adhesive from the periphery of the roller. Approximately 1.3 grams of wet adhesive was transferred by the figurated roller to each 12 inch x 12 inch tile passing through the printing machine. The tiles were allowed to dry at ambient temperature and humidity. Separate tiles were placed on alkaline subconcrete, glass, wood and vinyl asbestos subfloors and loaded at 20 pounds/ square foot at 160 F. At the end of three days, the tiles were removed from the subfloors and all exhibited a release strength between and 200 grams/inch.
Referring to FIGS. 5 and 6, the advantages of this invention are illustrated. In FIG. 5, a carpet tile 30 is secured to a subfloor 32 of any type. The tile 30 is removed from the subfloor 32 by grasping on one corner 34 thereof and pulling. As the corner 34 moves away from the subfloor 32, the foam backing 36 tears or delaminates to leave a part thereof adhered to the subfloor 32. To prepare the subfloor 32 to receive another floor covering, the foam backing 36 adhering thereto must be removed, as by scraping or the like.
Referring to FIG. 6, a carpet tile 10 of this invention is secured to a subfloor 38 of any desirable type. One corner 40 of the tile 10 is pulled back from the subfloor 38. The release strength of the adhesive means 16 is sufiiciently low to release from the subfloor 38 without tearing or delaminatin'g the foam backing 12.
It will be apparent that there is herein provided an improved floor covering and process of making the same which has all the advantages of this invention.
1. A removable carpet tile comprising:
a foam backing having a given tear strength;
a carpet layer bonded to the backing; and
adhesive means on the backing for securing the tile to an underlying surface and for removing the tile therefrom Without tearing the backing, the adhesive means comprising:
a multiplicity of discrete portions of adhesive material having a tack level in excess of the tear strength of the backing, the discrete portions having an area of less than about .01 square inch each and aggregating less than about 50 percent of the area of the backing.
2. The carpet tile of claim 1 wherein the foam backing has a bulk density of 8.5-19 pounds/ cubic foot and a tear strength of 1.0-1.5 pounds/inch.
3. The carpet tile of claim -2 wherein the release strength of the adhesive means is between .1-.9 pound/inch.
4. The carpet tile of claim 1 wherein the discrete portions have an area between .001-.002 square inch each.
5. In a removable floor covering comprising a foam backing having a bulk density of 8.519 pounds/cubic foot, a layer secured to one side of the foam backing the floor covering having a delamination strength of 1.0-2.25 pounds/inch and adhesive means on the other side of the foam backing for securing the floor covering to an underlying surface and for removing the floor covering therefrom without delamination thereof, the improvement wherein the adhesive means includes an adhesive material having a tack level greater than the delamination strength of the floor covering, the adhesive material being exposed in a multiplicity of discrete portions, less than .01 square inch each, aggregating between 10-50 percent of the area of the backing and providing a release strength less than .9 pound/inch.
6. The removable floor covering of claim 5 wherein the layer comprises carpeting bonded to the foam backing.
7. The removable floor covering of claim 6 wherein the adhesive material has a tack level between 1.25-1.75 pounds/inch when applied in a film of 001-002 inch thickness.
8. The removal floor covering of claim 6 wherein the discrete portions are between .001 and .002 square inch in extent.
9. The removable floor covering of claim 8 wherein the discrete portions are circles of diameter between .04 and .05 inch.
10. The removable floor covering of claim 5 wherein the release strength of the adhesive means is between .1.9 pound/inch.
'11. The removable floor covering of claim 6 wherein the carpeting comprises a grain direction, part of the discrete portions visibly contrast with the foam backing and the contrasting part of the discrete portions describe an arrow corresponding to the grain directions.
12. The removable floor covering of claim 6 wherein the floor covering is square and the discrete portions of adhesive are distributed within a plurality of spaced apart sets each of which comprise a long axis and a substantially perpendicular short axis, the sets in each quadrant of the floor covering having the long axis parallel to a line defined by the corner and the center of the floor covering.
13. The removable floor covering of claim 12 wherein the cumulative area of the discrete portions within each set aggregate less than percent of the area of the backing covering the set.
14. The removable floor covering of claim 6 wherein the maximum release strength of the adhesive means is between .6 and .9 pound/ inch.
References Cited UNITED STATES PATENTS 3,014,829 12/1961 Curtin 161-160 3,402,094 9/1968 Levitch 161-63 3,463,690 8/1969 Converse et a1. 161-159 3,586,598 6/1971 Beemer 161-67 WILLIAM J. VAN BALEN, Primary Examiner U.S. Cl. X.R.
UNETED STATES PATENT orrrer CERTE'FECA'EE Cl? CCRRECTWN Patent No. 704 Dated November 28 1972 Inventor(s) Jurgen F. BahlO It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:
Column 2, line 53, following typically" delete "and."
Column 3, line 24, change "0.1" to .O1--
Column 3, line 36, change "strength" to "strengths- Column 3, line 50, change "20" to -24-.
Column 6, line 11, change "directions" to -direction.
Signed and sealed this 10th day of July.197 3,
EDWARD M.FLETCHER,JR. RENE TEGTMEYER Attesting Officer Acting Commissioner of Patents :ORM po'wso $65) USCOMM-DC scam-ps9 ".5. GOVERNMENT PRINTING OFFICE 1969 0-366-334,