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Патент USA US2405235

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, 19%. ' _
Filed Dec. ' 5,
22 ‘
Basra-‘MM mg. Bab“ l
Patented Aug. 6, 1946
Boardman M. Randall, Portsmouth, N. H., assign
or to TekWood, 1110., Lakeport, N. H., a corpo
ration of New Hampshire
Application December '5, 1942, Serial No. 468,009’
7 Claims. (Cl. 154-453)
This invention relates to an improved composite
board which has particular utility as an underlay
for linoleums and the like resilient or compres
sible floor coverings although it is suitable also
for various other structural purposes as, for in
having surfaces protecting the plywood core- from
detrimental attack by moisture.
It is a further object of the present invention
to provide an underlay which has stiffness and
resiliency capable of permanently bridging de
stance, packing crates, walls and the like.
pressions and cracks in a sub-floor and which is
Any use of a stiff underlay for ?oor coverings
of the nature of linoleum usually presupposes a
ous barrier sheets which constitute also a means
protected against warping by moisture impervi
permitting differential expansion and contraction
sub-?oor having irregularities of surface, joints.
etc., which would be impressed in the linoleum ll) without danger of breaking the cement bond be
tween the ?oor covering and the underlay
or other floor covering and thereby be made visi
Another object is to combine these mentioned
ble at the surface of the covering if the latter
qualities of stiffness and resiliency in an underlay
with or without a felt backing were laid directly
‘whose over-all thickness dimension is commer
on the sub-?oor. Thus, any effective underlay
must have sti?ness and resiliency capable of per 15 cially acceptable.
manently bridging depressions and cracks in the
.A further object of the invention is the provi
sion of a plywood underlay as above described
sub-?oor, and provision also must be made to
having a protective surface thereof which func
prevent warping of the underlay and to permit
tions asthe usual lining felt to which. the ?oor
relative lateral shifting of the underlay and the
floor covering to take care of differential expan 20 covering is adhesively af?xed, thereby eliminating
the necessity for a special lining felt.
sions and contractions which otherwise would
A feature of the invention resides in utilizing
break the bond between the linoleum and the
a moisture impervious substance. which continues
inde?nitely rather tacky, and a water insoluble
I am aware that it has been proposed hereto
fore to use plywood as an underlay for ?oor cov-_ 25 substance which sets to relative hardness and
provides a strong and permanent bond. in the
erings; and also laminated ?bre board structures.
midst of the underlay as well as constituting
Actual experience has shown, however, that the
with the tacky substance a de?nite barrier
prior plywood underlays have been open to attack
against passage of moisture.
by moisture with consequent warping and fre
It is, moreover, an object of the invention to
quent breaking of the cement bond between the
generally improve composite board structures
linoleum and the underlay and also of the bond
and particularly such structures used as under
between the plies of the underlay. This produces
lays for ?oor coverings.
bulging or cracking of the ?oor covering which,
The mentioned objects and results may be at
aside from its unsightly appearance, causes un
tained by employing a stiff sheet of wood as a
even wear at the affected regions. The prior
core for the underlay, which preferably will be
laminated ?bre board structures have not been
satisfactory because they are compressible and
gradually become molded to the contour of the
plywood, and applying to each face of the wood
core a paper sheet impregnated with a moisture
impervious substance that, for at least one paper
?oor very soon become visible at the surface of ~10 sheet has the further characteristic that it com
tinues inde?nitely rather tacky.
the ?oor covering.
Between each sheet barrier and the wood core
The plywood underlay heretofore proposed has
a thin ?lm of water insoluble adhesive constitutes
been a plywood board of the order of half an
a bond between the wood core and the barrier
inch or thereabouts in thickness and comprised
sheet and, in conjunction with the barrier sheets,
of ?ve or more plies, presumably in an attempt
effectively insulates the wood core against mois
to minimize the action of moisture thereon. A
ture. Preferably the Water insoluble ?lm is one
thick underlay is objectionable as it raises the
having strong aflinity for both the wood and the
surface of the covering to such an extent, fre
impregnated paper ?bres but which does not
quently, as to interfere with the proper operation
greatly penetrate beyond the surface of the im
of doors and is otherwise objectionable. Hence,
pregnated paper. Thus, when the water insol-_
an object of the present invention is the provision
uble ?lm sets to hardness the ?bres‘ in the midst
of a thin plywood underlay that is rigid to resist
of the paper sheet continue capable of slip rela
deformation under the weight of a person and
sub -floor, and irregularities and cracks in the sub
resilient to spring back to its origina1 ?at condi
tion when relieved of 'an unusual pressure and
tive to each other, thereby to permit differential
expansion and contractionas between the‘ floor
covering and the underlay without danger of
breaking the bond between these two.
The paper barrier sheets preferably are rela
tively thin. They may be, for example, of felt
ed ?bre variety, as paper felt, felted under con
siderable pressure so that the barrier sheets on
two faces, of the wood core do not detrimentally
eral stresses at the regions of attachment. Thisi
permissible shearing of the paper barrier relieves‘
the cement bond between the ?oor covering and‘:
the underlay of the stresses which otherwise‘
might break the bond. Any suitable paper may‘
be employed for the barrier sheets 22, but I have
found a paper felt to have desirable character~
istios of strength and ability to absorb substan—
add to the over-all thickness of the underlay.
Yet the impregnated felted ?bre structure of
tial amounts of the asphalt or other moisture im
each sheet and the water insoluble bonding ?lm '10 pervious agent. The paper sheets 22 may be rela
effectively resist the passage of moisture and
tively thin, for example, 16 thousandths of an
permit relative lateral shifting of mid-?bres for‘ inch in thickness, thus adding only slightly to
the purpose above explained.
the overall thickness of the underlay. Yet these
In the accompanying drawing,
sheets, treated as above, e?ectively combine with
Fig. 1 is a vertical sectional view through a 15 the urea resin glue to insulate the wood core
floor having my improved underlay thereon and
having a linoleum floor covering laid upon the
against absorption of moisture from the water
soluble cement, usually of lignin variety, em
, ,
‘ ployed for attaching the floor covering to the
Fig. 2 is a perspective view of a fragment of a
underlay, and from atmosphere. Also sheets of‘
corner portion of a sheet of the improved under 20 this mentioned thinness can effectively perform
lay on an enlarged scale, with corner portions
the function of providing ?exibility between the
of the barrier sheets pulled away from the core.
linoleum and the underlay which accommodates
Referring to the drawing, Fig. 1 shows a rough
di?erential expansion and contraction as be
under ?ooring Ii! on the usualjoists l2, and a
tween the ?oor covering and the underlay.
top ?ooring .Monthe under floor. As illustrat
The term “sub-?oor” is employed herein in the
ed, worn depressions l5 and cracks IT between
broad sense of meaning any rough and irregular
the ?oor boards are exaggerated somewhat to
floor or other support upon which the composite
board structure may be spread.
emphasize the bridging ,characteristics of the
improved underlay l6, which is shown laid over
In use, my improved underlay will be arranged
the irregular surface of the top ?oor 14. A ?oor 30 as illustrated in Fig. 1, and may if desired be
covering [8 is laid upon the underlay.
cemented to the sub-?oor, although preferably it
- Referring to Fig. 2, the underlay comprises a
will be attached by nails or drive screws not
stiff and resilient wood core 20 preferably com-'
shown. The underlay is applied to the ?oor pref~
posed of three plies of wood veneer which in a
erably with the parallel grains of more than one
practical embodiment of the invention each may 35 ply crossing the cracks of the ?oor. The underlay
have thickness approximating 1/20 of an inch.
as is seen in Fig. 1 bridges any depressions and
They may bethicker or thinner as desired and
cracks in the sub-?oor but due to its characteris
are combined with crossed grains. The num
tic resiliency it may be temporarily depressed into
ber of plies may be varied to suit speci?c pur
such a depressionbut it will spring back as soon
poses. The veneers preferably although not nec
as the depressing force is removed. The barrier
essarily are from deciduous woods, as beech,
sheet 22 on the underside of the underlay com
birch, for instance, which have close grain and
bined with the Water insoluble ?lm of glue 3!]
are strong and permit the‘ use of a thinner core
between it and the wood core effectively insulates
than one made from weaker wood of a more
the core againstfmoisture which may come up
open grain. The barrier sheets 22 on opposite 45 through the floor cracks or otherwise ?nd its way
faces of the plywood preferably are felted paper
between the ?oor and the underlay, The upper
sheets impregnated rather generously with a
impregnated barrier sheet 22 coacting with its
suitable 'water impervious substance such, for
associated ?lm of water insoluble glue 3!! similarly
example, as asphalt. The asphalt or other sub-'
effectively insulates the core at the upper side
stance preferably will be of a consistency and
against moisture from the linoleum cement and
from atmosphere.
type which can readily penetrate the felted paper
sheet as a liquid and which will continue inde?
The underlay ordinarily will be'supplied com_
nitely to have a rather tacky character and feel.
mercially in rectangular sections of size to‘ be
In the drawing, Fig. 2, the water impervious
conveniently transported and handled, such as 4:
substance is indicated at 26 by the irregular dots
foot square sections or larger or smaller.
dispersed among the promiscuous lines 28 which
The plies of the core preferably are bonded
represent the feltecl?bre of the paper.
one to another by a water insoluble adhesive or
According to the invention, said barrier sheets
glue as, for instance, a urea resin, which exists
of paper 22 are strongly bonded to the plywood
as a water impenetrable ?lm between each pair
core by a water insoluble ?lm of glue, indicated
of plies.
in Fig. 2 by the stippling 3B. This glue 30 may
While the barrier sheets are above described
be of any suitable kind but I have found that urea
as identical, this need not be the case as the
resin glue has a satisfactorily strong amnity for '
under barrier sheet need not be a paper felt but
both the woodgandr the impregnated paper and
can be harder, as a kraft or other harder sheet
that it does not greatly penetrate either the sur 65 and can be rendered water impermeable by a
face of the wood or go deeply into the structure
harder asphalt having a higher melting point, as
of the paper under the combining pressure and
its main function is to prevent the wood core
the heat required for setting the resin. In the
from being subject to moisture that may be pres
case of the paper barrier sheets I consider this
ent in the air in contact with the lower surface
important in that it leaves the matted ?bres in 70 of the underlay, as when the underlay overlies a
the midst of the paper sheet restrained against
cellar, for instance.
lateral relative movement only by the asphalt
which is not set-to hardness andthus the paper
can to a needed extent shear laterally at'this
The underlay is made by combining. the various
woodveneer plies and the asphalt-impregnated
‘facing sheets with‘ liquid bonding ?lms of the
mid region as differential expansion imposes lat 75 thermo-setting resin'in a ?at plate press under
suitable pressure, as two hundred pounds per
square inch and, where the wood plies are bal~
anced, as by having an odd multiple of plies, at
a temperature suf?cient to set the resin adhesive
or to convert it to its infusible form. The tem
perature may be two hundred ?fty degrees Fahr
paper and strongly adhering to both the wood and
the surface ?bres of the barrier sheet.
3. A composite board comprising a core sheet
of a plurality of plies of wood veneer combined on
each side of the core with a barrier sheet of thin
felted paper impregnated with asphalt and a
water insoluble thermosetting resin ?lm having
af?nity for both the wood and the asphalt-im
effect the conversion. At this temperature the
pregnated paper and strongly adhering to both
asphalt in the facing paper sheets is liquid which
prevents the liquid resin from penetrating the 10 the wood surface and the surface ?bres of the
barrier sheet.
paper sheets to any deleterious extent.
4. A composite board comprising a core sheet
When the plies are unbalanced, that is, there
enheit, or thereabout, maintained long enough to
of a plurality of plies of wood veneer combined
on each side of the core with a barrier sheet of
pressing, in a hot room at say around one hundred 15 relatively thin felted paper impregnated with
asphalt and a ?lm of urea resin glue strongly ad
twenty degrees Fahrenheit for a sufficient time
hering to both the wood surface and the surface
as six to twelve hours to set the adhesive, a suit
able catalyst being used with the adhesive to ob
?bres of the barrier sheet.
5. A composite board comprising a sheet ele
tain setting or polymerization of the resin with
in this temperature and time to produce a ?at 20 ment of wood combined with a facing barrier
sheet of felted paper thinner than the wood sheet
composite board.
and impregnated with asphalt, and a ?lm of urea
I claim:
is an even multiple of plies, it may sometimes be
preferable to place the composite board, after
1. An underlay for resilient ?oor coverings
resin glue strongly adhering to both the wood sur
comprising a thin wood core composed of three
face and the surface ?bres of the barrier sheet.
6. A composite board comprising a sheet ele
plies of thin wood veneer combined with a water 25
insoluble glue and with crossed grains forming
ment of wood faced on at least one side with a
a composite board balanced to resist warping in
sheet of ?brous material thinner than the wood
sheet and permeated by a moisture impervious
any direction and rigid to resist deformation due
substance having the characteristics of asphalt
to normal pressures thereupon and resilient to
spring back upon removal of abnormal pressures 30 including the character that it continues tacky at
the exposed surface of the facing sheet.
thereupon, a lining felt bonded to a face of said
7. An underlay for ?oor coverings comprising
core by a wtaer impermeable adhesive and said
a wood core, a felted ?brous facing sheet on the
felt being permeated with a water insoluble sub
core, a thermosetting adhesive bonding the wood
stance su?‘iciently plastic to permit displacement
of the ?bres of the felt parallel to the face there 35 core and facing sheet together, and a moisture
of, and a water impermeablepaper sheet af?xed
to the opposite face of said core.
2. A composite board having a stiff and resil
ient core of wood combined on each side of the
core with a barrier sheet of paper impregnated
with asphalt, and a Water insoluble ?lm of a
thermosetting resin adhesive having affinity for
both the wood and the asphalt-impregnated
impervious substance impregnated within the
facing sheet, said adhesive having a setting tem
perature of the order of two hundred and ?fty
degrees Fahrenheit, and said moisture impervious
substance having the character that it is in liquid
state at the said setting temperature of the ad
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