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Description  |
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FIELD OF THE INVENTION
This invention relates to floor tiles 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 T and G edge
bond.
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
in 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 atmosphere. 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 is 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 board 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 oonsisting 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 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.
Attrition resistant flooring can be applied to an area by a method which
includes the steps of: placing a plurality of tiles in a central area,
there being overhanging-underfitting relationship of straight line
boundary portions which in the unadhered condition permits two adjacent
tiles to be slideably adjustable with respect to each other, whereby each
tile has overhanging-underfitting relationship with four adjacent tiles,
said tiles having boundary portions adapted for an underfitting
relationship along two edges which meet at a corner, said tiles being
adhered to each other only at the overhanging-underfitting zone, said
tiles not being adhered to the subflooring, said adhering of
overhanging-underfitting portions being the only limitation to the fitting
of an edge of a tile to the edge of its adjacent tile; trimming tiles at
the periphery of the area; and anchoring selected tiles at the periphery
of the area to the sub-flooring while retaining the non-adhering
relationship of the floor tiles and sub-flooring throughout such central
area.
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 overhanding 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.
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