U.S. patent number 3,902,293 [Application Number 05/330,159] was granted by the patent office on 1975-09-02 for dimensionally-stable, resilient floor tile.
This patent grant is currently assigned to Atlantic Richfield Company. Invention is credited to Homer Breault, Alvin E. Witt.
United States Patent |
3,902,293 |
Witt , et al. |
September 2, 1975 |
Dimensionally-stable, resilient floor tile
Abstract
A multilayer floor tile is so dimensionally stable that large
gymnasiums can be floored with it while achieving sufficient
resilience to be suitable as a basketball floor. The bottom layer
imparts durable resiliency because it is a sheet molded from a
tangled network of thermoplastic fibers containing cells of gas at
superatmospheric pressure. Wafer board provides the principal
thickness of the floor tile and there can be one or two strata of
wafer board. The top wear-resistant layer is relatively thin, and
may comprise hardwood parquet, chip board, particle board, or other
type of wood-derived structure having attrition resistance because
of the in situ polymerization subsequent to impregnation with the
combination of fire retardant and a monomer rich precursor for a
polymerized plastic such as methyl methacrylate. The top layer has
about the same rectangular dimensions as the contiguous strata of
waferboard, but is secured thereto in a staggered arrangement
providing overhanging portions, so that a major portion of a
subflooring area may be laid by adhering each of two overhanging
edge portions of a first tile to the boundary portions of two tiles
adjacent to such first tile. Thus, the tiles are simply laid
because at least a portion of the vertical edges of wafer board
layers are in abutting relationship with each other, but the
overhanging portions help to lock the tiles together. Gymnasium
floors or other large areas can be quickly laid with hardwood
parquet because of such simplicity of positioning and locking the
tiles together.
Inventors: |
Witt; Alvin E. (Pine Glen,
PA), Breault; Homer (Pine Glen, PA) |
Assignee: |
Atlantic Richfield Company (Los
Angeles, CA)
|
Family
ID: |
23288551 |
Appl.
No.: |
05/330,159 |
Filed: |
February 6, 1973 |
Current U.S.
Class: |
52/392; 52/388;
428/60; 428/77; 428/201; 428/909; 472/92; 428/297.7; 428/44;
428/63; 428/192; 428/305.5 |
Current CPC
Class: |
E04F
15/02 (20130101); E04F 15/22 (20130101); Y10T
428/16 (20150115); Y10T 428/20 (20150115); Y10T
428/249941 (20150401); Y10S 428/909 (20130101); Y10T
428/24777 (20150115); Y10T 428/195 (20150115); Y10T
428/24851 (20150115); Y10T 428/249954 (20150401) |
Current International
Class: |
E04F
15/22 (20060101); E04F 15/02 (20060101); E04F
015/16 () |
Field of
Search: |
;161/151,156,162,159,38,37,44 ;52/388 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schulz; William E.
Attorney, Agent or Firm: Ewbank; John R.
Claims
We claim:
1. A floor tile consisting essentially of:
at least one strata of a wafer board panel forming a wafer board
layer in which a variety of sizes of wafers of wood are oriented
with sufficient variation of grain orientation to internally
compensate for humidity-induced dimensional changes subsequent to
the molding of the wafer board, the wafer board layer imparting
dimensional stability throughout all humidity variations to which a
floor is subjected, said wafer board layer constituting a major
portion of the thickness of the tile, the vertical walls of the
wafer board comprising significant unbonded zones whereby the
contact zone between adjacent tile serves as a vent for promoting
moisture equilibria between the subflooring and atmosphere and
whereby floor laying is expedited by placement of such vertical
walls of adjacent tiles in abutting relationship;
an attrition resistant top layer consisting of wood structure
impregnated with a mixture of a fire retardant and a monomer rich
precursor and in situ polymerized, said top layer being bonded to
the wafer board layer throughout only most of the area of the top
layer in a staggered manner to provide overhanging portions adapted
for horizontal engagement with matching portions of adjacent tiles;
and
a bottom layer of a molded sheet of a network of synthetic organic
resinous thermoplastic filaments containing spheroidal cells of gas
at superatmospheric pressure, said sheet imparting to the tile a
controlled resiliency with substantially no compression set in
normal usage, said sheet being bonded to the lowermost strata of
the wafer board layer.
2. A rectangular floor tile consisting essentially of:
a bottom layer of a molded sheet of network of synthetic organic
thermoplastic polymerized resin filaments containing cells of gas
at superatmospheric pressure, said sheet imparting resiliency to
the tile;
at least one layer of plastic bonded wafer board, whereby wafer
board constitutes the principal thickness of the tile, said molded
sheet of network of filaments being bonded to the bottom portion of
the wafer board; and
a layer of wood structure impregnated with both a fire retardant
and in situ polymerized polyalkylmethacrylate resin as a
wear-resistant surface, said layer having substantially the same
dimensions as the wafer board layer, and said wear-resistant layer
overhanging two corner-meeting edges of the next lower strata of
wafer board, a principal area of said wear-resistant layer being
bonded to a staggered principal area of said wafer board layer.
3. In a flooring system for areas having at least one dimension of
sufficient length that variations in moisture content cause
troublesome dimensional changes in wooden floors, the improvement
which consists of:
a plurality of interfitting tiles, each tile comprising the
combination of a bottom layer consisting of a thin resilient sheet
of a molded network of compressed gas cell-containing synthetic
organic thermoplastic polymerized filaments, such sheet being
designed for placement on a subflooring;
at least one layer of weight-supporting molded wafer board whereby
wafer board constitutes the principal thickness of the tile, said
layer of network of gas-filled fibers being bonded to the bottom
portion of the wafer board; and
a layer of in situ polymerized impregnated wooden structure as a
wear-resistant top layer, a major portion of the area of said
wear-resistant layer being permanently adhered to the major portion
of the area of the underlying strata of wafer board in a staggered
manner whereby boundary face portions of a strata of the wafer
board are exposed along two edges which meet at a corner, whereby a
central tile may have overhanging-underfitting contact with four
adjacent tiles.
4. A tile in accordance with claim 2 in which there are two strata
of waferboard, the upper wafer board strata being staggered with
respect to both the polymethacrylate-impregnated layer and the
lower wafer board strata, whereby grooves are formed along two
corner-meeting edges and whereby overhanging tongues are formed
along the other two corner-meeting edges.
5. A tile in accordance with claim 2 in which adhesive is provided
adjacent two corner-meeting edges, such adhesive being adapted to
bond with overhanging portions of two adjacent tiles.
6. A tile in accordance with claim 2 in which a single strata of
wafer board constitutes the principal thickness of the tile.
Description
FIELD OF THE INVENTION
This invention relates to gymnasium floor systems having the type
of resiliency satisfying basketball players, to floor tiles
suitable for creating such floor systems, or other floor systems
where resiliency is important, and to methods for laying resilient
floors by adhering tiles to adjacent floor tiles.
BACKGROUND OF THE INVENTION
Numerous problems have plagued both the design and maintenance of
gymnasium floors. Hardwood has had many advantages, but maintenance
thereof has sometimes been costly. For some hardwood floor
situations such as in foyers, requiring no resiliency, the use of
hardwood impregnated with a suitable plastic monomer and the in
situ polymerization thereof has provided an impregnated structure
having sufficient durability to reduce maintenance costs
significantly. The plastic impregnated wood is not completely free
from troublesome amounts of dimensional change attributable to
changes of humidity. The humidity-induced expansion of
plastic-impregnated hardwood of the prior art has not been as
troublesome in small areas as in gymnasiums or other large areas
covered with a flooring involving wood products. Gymnasium floors
have sometimes buckled because large forces are generated by the
humidity-induced expansion of unmodified hardwood.
Plywood has less humidity induced expansion than wooden strips.
Various combinations of wooden strips, resilient pads, plywood
subflooring, and hardwood floor have sometimes been employed for
seeking to achieve a combination of dimensional stability and
limited resilience for the total floor structure. Basketball
players do not like to play on a concrete or other floor completely
lacking resiliency. Basketball players can recognize the presence
or absence of the desired degree of resiliency in a gymnasium
floor. A resilient floor is significantly more valuable than an
unyielding floor because its resiliency can be recognized by some.
Gymnasium floors have been constructed with steel channels anchored
to the concrete subflooring, with the hardwood securely anchored at
a sufficient number of points to the steel channels to bring about
compression and stretching of the hardwood instead of dimensional
changes, as described in Robbins U.S. Pat. No. 3,271,916. Attempts
have been made to provide air conditioning systems sufficiently
reliable and perfect to minimize humidity changes for overcoming
the problems of dimensional change in hardwood floors, but costly
buckling has sometimes occurred at gymnasiums equipped with air
conditioning.
Because all of the hardwood systems have involved so much
maintenance and installation expense, a variety of alternatives,
including polyurethane flooring and other plastic flooring have
been employed in gymnasiums. Although hundreds have struggled with
the problem, architects have long been frustrated by the
conspicuous absence of any moderately priced system for building a
resilient basketball floor using a low-cost field application and
permitting long-term low-cost maintenance, notwithstanding the
long-standing demand for such moderately priced basketball
floors.
SUMMARY OF THE INVENTION
In accordance with the present invention, a floor system is
provided having the combination of wear resistant top surface,
long-lasting resiliency, simplicity of field application, low
maintenance requirements and dimensional stability throughout all
of the plausible changes of humidity. Such floor system is achieved
by the use of a floor tile having a plurality of layers bonded to
each other at the factory. The bottom layer is a sheet of molded
tangle of thermoplastic fibers containing a multiplicity of
spheroidal cells of compressed gas within the fiber. Thus, the
resiliency of each fiber has been attributable primarily to the
closed cells of gas at superatmospheric pressure in the fibers.
Such resiliency is analogous to the resiliency of a tennis ball, as
distinguished from the resiliency of a sponge rubber ball in which
the gas in the cells is at about ambient pressure instead of
superatmospheric pressure.
A major portion of the tile thickness consists of a wafer board
composition, thereby achieving outstanding dimensional stability.
Such major thickness of the tile, with the wafer board edges of
adjacent tiles being in abutting relationship permits ease of
laying the floor tiles. There can be one or two or more lamina of
such wafer board in such major thickness of the tile.
A relatively thin top layer provides toughness and a wear-resistant
surface. Such top layer requires minimized maintenance attributable
to the impregnation and in situ polymerization of methyl
methacrylate or other appropriate monomer or impregnated plastics.
A flame retardant is also impregnated into the top layer and sealed
therein by the in situ polymerization of the monomer. A variety of
synergistic advantages are attributable to such combination of
wood, flame retardant, and in situ polymerized plastic. The wear
resistant layer is bonded to most of the area of its underneath
wafer board member but has an overhanging portion adapted for
contact with boundary portions of two adjacent wafer board members.
Factory applied pressure sensitive adhesive may, if desired, be
employed so that at the time of field application, the floor tiles
are laid so that each tile is bonded to four adjacent tiles. If
there is only a single lamina of wafer board, then somewhat wider
overhanging relationships may be advantageous. If there are two
lamina of wafer board, whereby tongue and groove associations of
the overhanging portions of adjacent tiles are feasible, then the
depth of groove (corresponding to length of tongue) can be only a
small fraction of the tile dimension. Pressure sensitive adhesive
factory applied in the groove is protected by its remote location
until the laying of the tile, thus increasing the convenience of
the tile to the contractor laying the floor. No anchoring to the
sub-floor (e.g., a concrete floor) is necessary or desirable
throughout most of the central area. At the periphery, if desired,
and particularly in zones in which tile trimming is needed, the
tiles can be suitably anchored to the sub-floor. Much of the
central area of the floor can be adequately bonded together because
of the pressure sensitive adhesion of the overhanging portions of
adjacent tiles or because of the tongue and groove.
DESCRIPTION OF THE DRAWINGS
In the drawings, FIG. 1 is a schematic, exploded view of some of
the components of the embodiment of FIGS. 2-8, the staggered
relationship of the layers not being shown.
FIG. 2 is a top view of an embodiment of an assembled tile of one
embodiment.
FIG. 3 is a cross section of a portion of a tile, taken on 3--3 of
FIG. 2.
FIG. 4 is a schematic view of a portion of an area in which the
tiles of FIG. 2 are laid.
FIG. 5 is a schematic view of a thermoplastic filament having
spheroidal cells of gas at superatmospheric pressure.
FIG. 6 is a schematic view of a sheet molded from a tangled web of
filaments of FIG. 5.
FIG. 7 is a schematic view of an irregularly shaped wafer of wood
chipped from a log.
FIG. 8 is a schematic view of a wafer board resulting from coating
a plurality of irregularly-shaped chips of FIG. 7 with a precursor,
arranging such chips with random distributions of grain in a mold,
and pressure curing the chips into a wafer board.
FIG. 9 is an isometric view of a modification with a corner portion
shown in section to better show the groove and tongue.
FIG. 10 is a cross section on the line 10--10 of FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Concrete floors sometimes contain amounts of water or moisture
which vary from time to time, attributable to such factors as
recent pouring of the concrete, pouring as a slab on the ground
and/or other factors. It is important that the moisture content of
a concrete subfloor be allowed to equilibriate with atmospheric
moisture. The present invention features a plurality of floor tiles
laid in such a manner that at each zone where four tiles meet, as
well as at some edge zones between two tiles, vent paths are
provided between the zone of the subflooring and the atmosphere. At
the subflooring zone, there is an abundance of generally horizontal
paths for moisture diffusion because the resilient layer is a
molded tangled web of fibers (schematically shown in FIG. 6)
through which gas streams readily flow. Such molded sheet of
resilient material, thus aids the equilibriation between the
atmosphere and any moisture in the subflooring by promoting
vertical diffusion at the joints between the tiles rather than
through the tile.
Many types of resilient material are seriously damaged if a load is
applied for a period of weeks to significantly compress the
resilient material. An important feature of the present invention
is the utilization of a molded sheet of a network of fibers
comprising spheroidal chambers or cells of gas at superatmospheric
pressure. FIG. 5 is a schematic showing of fibers featuring
spheroidal chambers or cells containing compressed gas at a
pressure above atmospheric. The fibers with compressed gas cells
are adapted to be restored to excellent resiliency even after
prolonged significant compression.
Some conventional sponge rubber balls, when kept under a heavy
load, undergo "compression set" to develop a distorted
non-spherical shape after the load is removed. However, the ideal
tennis ball featuring compressed gas in an impermeable spheroidal
chamber, can withstand a heavy load for months and retain original
resiliency. Thus the ideal tennis ball has zero compression set and
its resiliency can accordingly be distinguished from the resiliency
of the previously described conventional sponge rubber ball.
Similarly, the sheets of networks of hollow (an abbreviated
requirement for containing compressed gas cells) fibers have
substantially no permanent compression set when the loads are less
than would burst any of the compressed gas chambers.
It can be noted that the sheets of a molded network of fibers
containing compressed gas have been designed primarily as underlay
for carpets. The concept that such sheets have ability for
imparting resiliency for gymnasium floors had never been
demonstrated prior to the present invention.
Heretofore floors have been laid by positioning tiles of
appropriate shape adjacent to each other. It is most convenient to
describe each laying of floor tiles which are square. It should be
recognized that the shape of the floor tile is suitable for floor
tile usage, and although square tiles have been popular, the
present invention embraces any and all other established floor tile
shapes such as rectangular, hexagonal, or the like.
Each of the several layers of a square tile 10 has substantially
the same horizontal dimensions as indicated schematically in FIG.
1. The resilient sheet 11 of tangled, hollow fibers is bonded to
the bottom of the next higher strata of a wafer board layer 12. The
wafer board layer is thick enough to permit convenient laying of
the tiles with some vertical walls of wafer board layers of
adjacent tiles in abutting relationship. No adhesive is provided
between the principal abutting walls between the floor tiles,
inasmuch as this is a gas permeation zone allowing the concrete
floor to gain and lose moisture. Such absence of adhesive between
the walls of the bottommost strata of the wafer board layer also
helps to make possible a limited amount of resilient movement
between the abutting edges of adjacent tiles.
FIG. 7 is a schematic view of a wafer. FIG. 8 is a schematic view
of a strata of wafer board. A variety of sizes of wafers of wood
are oriented with sufficient variation of grain orientation that,
after the molding of the wafer board, the variations in dimensions
in any chips attributable to changes in humidity, are compensated
for internally within the wafer board, whereby the molded wafer
board retains reliable dimensional stability throughout the entire
humidity range. Wafer board has been marketed with emphasis upon
its price and aesthetic decorativeness, and the present invention
represents a breakthrough in utilizing wafer board for floor tiles
to achieve dimensional stability throughout a wide humidity
range.
The top wear resistant layer is characterized by having a suitable
wood structure but is characterized primarily by being impregnated
with the combination of a fire retardant and a plastic which has
been polymerized within the wood after impregnation of the liquid
precursor mixture. Such chronology of impregnation of a liquid
precursor mixture followed by polymerization to an attrition
resistant plastic product is described herein as in situ
polymerization.
Most varieties of plastic impregnated wood, once the combustion has
started, tend to burn with even greater intensity than is possible
in ordinary wood. Monomers such as vinylidene fluoride or vinyl
chloride, which might impart flame retardancy have had engineering
disadvantages prompting selection of methyl methacrylate and other
flammable monomers for in situ polymerization of plastic. By the
combination of suitable fire retardants and the plastic, the
combination of wear resistance and safety from excessive fire
hazard is achieved. The wooden structure may be a hardwood parquet
tile or it may be a thin layer of wafer board or it may be a
particle board or any other type of wooden structure suitable for
floor usage.
Particular attention is called to the staggered positioning of the
top layer with respect to underlying layers. Only a portion of the
wear resistant layer is bonded at the factory to the next
underlying strata of unimpregnated wafer board. A small unbonded
boundary zone along two edges of such waferboard strata is thus
exposed. Moreover, the top layer overhangs the next underlying
strata to provide an overhanging projection along the opposite two
edges. The combination of the boundary zones of wafer board and the
overhanging projection of the top layer permits each tile to have
overlapping relationships with four adjacent tiles in a floor
laying technique which can proceed rapidly. Pressure sensitive
adhesive (with or without protective peelable strips) can be
applied at the factory to at least segments of the boundary
portions of the wafer borad face and/or to the under portion of the
overhanging projection of the wear resistant layer. Alternatively,
instead of applying adhesive at the factory, the adhesive could be
applied at the site while still providing a more rapid installation
of a gymnasium floor than has been conventional. The overlapping
relationships of the tiles overcomes problems attributable to floor
laying procedures requiring either adhesion of abutting vertical
walls of adjacent tiles or adhesion of central area tiles to the
subflooring.
Referring now to the drawings, FIG. 1 shows a modified exploded
view of the several components of the floor tile. A bottom layer 11
consists of a molded sheet of a network of compressed
gas-containing fibers or filaments. FIG. 5 is a schematic showing
of a series of pressurized gas chambers along the axis of a
filament employed in manufacturing bottom layer 11. The network of
such filaments is molded into a sheet schematically shown in FIG.
6. One brand of molded sheet of fibers having cells of compressed
gas is marketed as Pneumacel underlay for carpets. The molded fiber
network provides a resilient sheet which, so long as the
pressurized gas remains within the chambers in the fiber, retains
its initial resiliency even after prolonged periods of supporting
heavy weights. Thus, the substantially zero propensity to set when
compressed distinguished such resilient sheet from the several
conventional varieties of cellular plastic. In some sponge rubber,
relatively large gas cells are distributed in a random manner
inconsistent with the nature of the resilient fibers of layer 11.
In some cellular plastics, the porosity of the walls of the gas
cells permits gas to diffuse from and into such cells, such
cellular plastic tending to set when subjected to prolonged
compression.
A thin layer of adhesive 12 serves to bond the resilient sheet 11
to the next higher strata consisting of wafer board. In the
embodiment of FIGS. 1-8, there is only a single strata of
waferboard in a middle layer 13 of the tile. Such wafer board layer
13 constitutes a major portion of the thickness of the floor tile.
Wood chips or wafers such as shown schematically in FIG. 7 are
coated with a plastic, and assembled with the grains of the wafers
appropriately oriented, and with appropriate cavities between
wafers and with wafers bonding to each other at appropriate points,
as distinguished from a complete filling of the space with the wood
product. Thereafter, the wood wafers are pressure molded to provide
a structure schematically shown in FIG. 8. The wafers are bonded to
each other at certain zones so that there are cavities throughout
the panel and so that each wafer can undergo small dimensional
changes without weakening the inter-wafer bonding. Because there is
internal compensation within the panel, and a balancing of the
humidity-induced dimensional changes within each wafer, the panel
of wafer board has substantially no dimensional changes
attributable to variations in the moisture content of the
atmosphere. Humidity changes can bring about small dimensional
changes within each wafer. The nature of the inter-chip bonding,
and the variations in grain orientation are such that the wafer
board retains its originally intended dimensions throughout the
entire range of humidity changes. One brand of wafer board is
marketed as Aspenite panels as decorative competitor for plywood.
The absence of dimensional change while still utilizing a wood
product is a very important characteristic of the middle layer 13,
inasmuch as the edges of portions of middle layers of adjoining
tiles are abutting, whereby buckling of the floor would readily
occur if there were moisture-induced expansion of the wood
structure in tiles merely placed upon (not adhered to) the
subflooring.
In order to focus attention upon the fact that an attrition
resistant layer 14 embraces substantially the same floor area as
the wafer board 13, FIG. 1 shows such two layers vertically
displaced without staggering. The attrition resistant layer 14 is a
wood structure, such as a wire stapled assembly of hardwood strips
suitable as a hardwood tile for parquet flooring. Alternatively,
the layer 14 might be a particle board, plywood, or other wooden
structure. Whatever type of wooden structure is employed, the
attrition resistance is obtained by reason of the impregnation of
the wooden structure with a precursor characterized by a mixture of
plastic monomer and fire retardant. Of particular importance, the
wooden structure of the attrition resistant layer 14, after
impregnation with the combination of flame retardant and monomer,
is polymerized in situ. Certain advantages accrue from promoting
such polymerization predominantly by radiation (i.e., generally
non-catalytic, but comprising the thermal polymerization
attributable to the restricted cooling of the radiant
polymerization) from radioactive cobalt. The substantial absence of
catalysts in the in situ polymerized plastic imparts outstanding
attrition resistance to the top layer. The attrition resistance of
the hardwood or other wooden structure is enhanced by the
combination with the in situ polymerized plastic.
Because of the outstanding attrition resistance of the top layer
14, the problem of preserving an attractive appearance for the top
layer is greatly simplified, thus providing a maintenance advantage
for the plastic-wood structure.
The floor tile of FIGS. 1-8 features a staggered mounting of the
attrition resistant layer 14, as shown in the top view of FIG. 2.
Thus, the principle portion of the area of the attrition resistant
layer 14 is aligned with a principle area of the wafer board 13,
but the staggering exposes two boundary zones 15 and 16 which meet
at a corner of the tile. At the diagonally opposite corners of the
tile, there are overhanging lips 17 and 18 of the attrition
resistant layer 14.
The schematic sectional view of FIG. 3 shows that the tile 10
includes the resilient sheet 11, bonded by adhesive 12 to the
bottom of the single strata of wafer board 13, above which is
positioned an attrition resistant layer 14 having an overhanging
lip 17 which exposes boundary zones 15 of the wafer board 13.
At the factory, an adhesive 21 secures the attrition resistant
layer 14 to the wafer board 13. It is sometimes desirable to
provide factory application of pressure sensitive adhesive 22 to
the top of boundary zone 15 and/or underneath the surface of lip 17
of attrition resistant layer 14. Alternatively, adhesive can be
applied to one or both of such zones as a part of the laying of the
floor tiles. By either chronology, the floor tiles are locked
together by the adhesion between adjacent tiles at such overhanging
portions.
As shown in FIG. 4, a room 30 has walls 31, 32, and a subflooring
33. A plurality of floor tiles 10, corresponding generally to the
floor tile previously described, are laid so that the attrition
resistant layers of the tiles 10 are staggered with respect to the
wafer board layers. Particular attention is directed to the ease of
laying tiles 10 throughout the floor of a room. As a new tile is
laid down, its thickness of wafer board 13 can be positioned
adjacent one or more already laid tiles, and the overlapping lip 17
of the tile pressed against the boundary portions 15 of adjacent
tiles. In this manner, each tile is adhered to four adjacent tiles.
At the periphery of the room, where tile-trimming is ordinarily
required, the resilient layers can be adhered to the subflooring,
thus providing at least a partial anchoring of the entire floor
system to the subflooring while still permitting most of the floor
tiles to retain a controlled amount of independent vertical
resiliency of a type not readily achieved when each floor tile is
adhered to the subflooring.
An alternate embodiment of a rectangular floor tile is shown in
FIGS. 9 and 10. A floor tile 110 comprises a resilient layer 111
and a top attrition resistant layer 114 corresponding essentially
to that of the previously described tile 10. A principal thickness
of the tile 110 is designated as a wafer board layer 113 comprising
two strata, 151 and 152. As shown in FIG. 9, the staggering
relationships amongst the attrition resistant layer 114 with
respect to the upper wafer board strata 151 and lower wafer board
152 are such that tongue and groove fittings between adjacent tiles
are feasible, the overhanging portion of strata 151 constituting a
tongue 153 adapted to fit within a groove 154 formed between the
bottom of the attrition resistant layer 114 and the top of the
lower strata 152 of the wafer board layer 113. In order to achieve
a convenient insertion of the tongue in the groove at the time of
laying the floor, the depth of the groove 154 is less than the
magnitude of the overhang of tile 10. The fact that the bottom
layer 111 had adequate resiliency aids in the insertion of each of
the two tongues in their respective grooves as a tile is pushed
into engagement with two adjacent tiles. As shown in FIG. 10,
pressure sensitive adhesive can be distributed as a film 156 along
at least portions of the groove 154, whereby the tile may be
shipped from the factory with the pressure sensitive adhesive
factory applied, but without any protective paper thereover. It is
only at the time when the floor is being laid, and the tongue is
inserted in the groove that the pressure sensitive adhesive
encounters a surface to which it can bond. The remote location of
the pressure sensitive adhesive permits convenient handling of the
tiles prior to the laying of a floor while still providing adequate
bonding between adjacent tiles in the central area of the laid
floor.
Various other modifications for bonding a floor tile to two
boundary portions of adjacent tiles by reason of overhanging
portions are possible, and the overhanging lip of tile 10 or the
tongue 153 and groove 154 arrangement of tile 110 are illustrative
of methods for securing the floor tiles together without relying
upon the bonding between subflooring and tile or between the
vertical walls of abutting tiles.
Various modifications of the invention are possible without
departing from the scope of the appended claims.
* * * * *