Note: Descriptions are shown in the official language in which they were submitted.
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Title: TOOL FOR INJECTING SEALANT INTO CRACKS
This invention relates to the injection of sealant or filler
into cracks (including voids and such like recesses) in walls,
floors, etc, made of concrete, masonry, plaster, and the like,
and wood.
BACKGROUND TO THE INVENTION
The conventional techniques for filling small cracks tend to
fall into two categories. The light techniques produce what
amounts to just a surface coating of the sealant, with very
little penetration of the crack. The heavy techniques use
injection ports at spaced intervals along the crack; the
outside of the crack is covered with a sealing compound, or an
elaborate mechanical means is provided for sealing the port to
the wall; and then pressurized equipment injects the compound
into the crack. The light techniques, though inexpensive
enough, provide little more than cosmetic treatment; the heavy
techniques can work well enough, even to restore structural
integrity in some cases, but are limited by their high cost.
The invention is aimed at providing a tool which enables
sealant to be injected deep into the crack, and which is
inexpensive enough that the tool can be used on a one-time-use
basis, and preferably which is so inexpensive to produce that
it can be favourably priced when on the same counter shelf as,
for example, tubes of caulking.
The invention is aimed at providing a tool which is
particularly suitable for use with conventional tubes o~
caulking, sealants, adhesives, grouts, and fillers. The tool
is intended for use with conventional caulking injection-guns;
or, the injection can be done by manual compression of a soft
container.
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GENERAL FEATURES OF THE INVENTION
The invention makes use of a property of some synthetic
polymers -- notably compressible and elastomeric materials,
and especially soft foam materials -- namely, the ability of a
flat block of the material to conform intimately to a
nominally flat wall surface when pressed lightly against the
surface. A block of the elastically compressible, or
elastomeric, material is loaded against the wall surface by
means of a solid backing block, which enables the force
pushing the block against the wall to be spread evenly
throughout the elastomeric block.
The invention is herein described as it relates to sealing
cracks in walls, but it will be understood that the repair
sites may be in floors, or in other structures or articles in
which the sealing of cracks is required.
Sealant (or other injectable repair material) is injected
through a through-hole through the blocks, and out through an
exit-mouth in the elastomeric block, and into the crack. The
elastomeric material serves to seal the wall surface area
around the mouth of the through-hole, allowing pressure to be
built up, which produces good penetration of the crack,
without the sealant leaking or extruding between the block and
the wall surface.
The compressible elastomeric material preferably is expanded,
cross-linked, polyvinyl chloride foam material, that is formed
with an integral skin. Also, low density neoprene foam, and
some solid silicone and polyurethane-based elastomers may be
used.
The contact face of the elastomeric block may be flat,
concave, convex, or angled, as required for specific repair
sites. The degree of compressibility and elasticity of the
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material is selected with reference to the extent and size of
the crack, the viscosity of the sealant, the injection
pressure available, and the force available for holding the
block against the wall. Also, the dimensions of the block of
elastomeric material are important, as will be explained.
THE INVENTION IN RELATION TO THE PRIOR ART
Prior art from the field of filling cracks, which may be
considered relevant to the invention, includes the following
patent publications: US-2,815,895 (1957, Reed) US-4,509,884
(1985, Trout); US-4,884,922 (1989 Haq); US-5302,205 (1994,
Priddy). These references show more or less elaborate means
for forming a seal onto the wall surface around the crack, and
a means for injecting the sealant into the cracks. The
references do not show the use of a block of softly
compressible elastomeric material to provide the seal to the
wall surface, nor the use of a rigid or solid backing block to
enable the elastomeric block to be pressed firmly and evenly
against the wall.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
By way of further explanation of the invention, exemplary
embodiments of the invention will now be described with
reference to the accompanying drawings, in which:
Fig 1 is a pictorial view of a tool for aiding the operation
of injecting sealant into a crack in a wall surface, which
embodies the invention;
Fig 2 is a cross-section of the tool of Fig 1;
Fig 3 is a pictorial view of another version of the tool;
Figs 4a,4b,4c,4d are views of a component of a further version
of the tool;
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Fig 5 is a cross-section illustrating another version of the
tool.
The apparatuses shown in the accompanying drawings and
described below are examples which embody the invention. It
should be noted that the scope of the invention is defined by
the accompanying claims, and not necessarily by specific
features of exemplary embodiments.
As shown in Fig 1, the tool 20 comprises a backing-block 23,
made of rigid nylon, and a foam-block 25, made of soft,
elastically compressible, foam material. The two blocks are
of the same length and width dimensions, and are glued
together, face to face.
The foam-block 25 includes a contact face 27, which is adapted
for being placed in direct touching contact with the surface
of a wall. The contact face 27 is rectangular, and the
general manner of use of the tool 20 is that the tool is
placed in contact with the wall, over a crack 29 to be filled,
with the long dimension of the rectangle disposed along the
length of the crack (see Fig 2).
A through-hole 30 is located centrally of the blocks, and
extends right through both blocks. The through-hole 30
terminates at an exit mouth 32, which opens into the face 27.
At its other end, the through-hole 30 includes a tapered
socket 34. This is suitable for receiving the nozzle 36 of a
sealant injector 38. The sealant injector 38 may be, for
example, a caulking gun.
In operation, the person takes the tool in one hand, and
applies it to the wall, over the crack. The person places the
nozzle of the injector into the socket 34. The person holds
the injector in one or both hands, and presses the nozzle
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firmly into the socket, with a force whereby the tool is held
firmly against the wall surface. The force with which the
tool is held against the wall may be derived entirely from the
force with which the nozzle is pressed into the socket, or the
person may apply a separate force directly to the tool (e.g
with his other hand).
With the tool held firmly against the wall, the person may now
apply pressure to the injector, causing sealant to be injected
therefrom. The sealant passes through the through-hole 30,
and emerges from the mouth 32. It might be considered that
the sealant might, at this point, extrude between the wall
surface and the contact face 27 of the foam block -- and in
fact the sealant would do so if there were nowhere else for
the sealant to go, and if the sealant were injected at a high
enough pressure. However, the crack offers a path of smaller
resistance to the flow of sealant.
It will be understood that, for effective operation of the
tool, it is necessary to press the contact face of the foam
block so firmly against the wall surface that the sealant can
more easily enter the crack than it can extrude between the
foam block and the wall.
The designer must ensure that, when the sealant is injected,
the sealant goes into the crack, rather than between the foam
block and the wall.
The factors which determine where the sealant will go are:
- the magnitude of the force, as applied by the person, with
which the contact face of the foam block is pressed against
the wall surface;
- the conformability of the foam block to the wall surface,
and the ability of the foam block to form a seal with respect
to the wall surface;
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- the dimensions of the area of contact between the foam block
and the wall, both as to the dimension measured along the
length of the crack, and the dimension laterally across the
crack.
As to the force, the available force is that force which can
be applied by the person, using the hands and fingers. In
fact, the designer should see to it that the needed force is
on the light side, because sometimes the cracks may be in
hard-to-reach places, where it would be awkward for a person
to apply a large force.
As to the conformability of the foam material, the foam
material as noted herein is highly conformable to wall
surfaces, and to the (slight) irregularities normally found in
wall surfaces. The foam material is of such a consistency
that if an object such as a finger is pressed lightly into the
foam, the foam deflects, and, in effect, the foam "flows"
around the end of the object, accommodating the object into
the surface of the material. When the object is withdrawn
from the surface of the material, the surface regains, or
rebounds to, its original flatness. However, often this
rebound is not immediate -- that is to say, the impression of
the object may remain in the surface for a time after the
object is withdrawn. Whilst a reasonable rebound time may be
tolerated, the elastomeric material should be selected on the
basis that a rapid rebound is one of the required properties.
For the purpose of the invention, the foam material is the
more suitable the more the material has this combination of
conformability with a rapid rebound characteristic. It is
recognised that with the soft foam material as described, the
light force required to make the foam conform to the wall
surface, to the extent required for the sealant to enter the
crack, and not extrude between the foam and the wall, is the
kind of force that can be applied with the fingers.
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As to the dimensions of the contact face of the foam-block,
the foam-block as shown is a rectangle 60-70 mm long and 30-
40 mm wide. Thus, the length of the leakpath through which
leaking sealant would have to travel is about 15 mm width-
wise, and about 25 mm length-wise.
It is recognized that these force-, conformability-, rebound-
and dimensional-properties, as desired, can be met in and by
the structures as described herein.
The designer should also be concerned that the nozzle 36 of
the in~ector should form an adequate seal within the socket
34. It would hamper the operation of filling the cracks if
the sealant were to leak out around the nozzle due to the
nozzle being a poor fit in the socket. Of course, a little
leakage of sealant at this point is tolerable.
The designer must see to it that sealant will not leak around
the nozzle when the nozzle is pressed into the socket with the
same magnitude or level of force as is being used to press the
block against the wall. Then, the tool can be held against
the wall by pressing the nozzle into the socket.
The designer should also bear in mind that nozzles vary as to
size and shape. It has been found that satisfactory results
were achieved when the socket was a tapered or conical, from
10 mm in diameter, down to 6 mm.
When the nozzle is pressed into the socket with the kind of
fairly light pressure needed to hold the tool against the
wall, it is found -- the nozzle being conical, as mentioned --
that that same light pressure is enough to ensure that very
little sealant leaks past the nozzle.
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In use, the person lays the tool against the wall, and
squeezes the sealant out. The sealant being generally very
viscous, it takes several moments for the sealant to flow into
the crack. With the dimensions of the blocks as described, an
easy-to apply hand pressure will result in sealant travelling
along the crack, and emerging from the ends of the foam block,
and from the crack. When the person sees beads of sealant
starting to appear in the crack, past the ends of the tool, he
stops squeezing the sealant out, and allows any back-pressure
to dissipate; and then he repositions the tool over the next
portion of the crack. Again, he squeezes the sealant out
until a bead of sealant again appears in the crack, beyond the
end of the tool. This continues until the whole length of the
crack is filled.
Fig 3 shows an alternative form of tool, in which the tool is
especially adapted for filling cracks in the corners of rooms
etc. The contact face in this case is of a right-angle-V-
shape, as shown. Again, the important dimensions are that the
leak-path distances from the mouth of the through-hole is 25
mm lengthwise and 15 mm widthwise.
The tool as described is very inexpensive to produce. The
tool may be offered for sale at the same sales-counter as the
tubes of sealant, caulking guns, etc. The person will then
pick up one of the tools when he buys the sealant. The tool
is inexpensive enough that the person can purchase it on a
one-time-use basis. For this reason, ease of clean-up of the
tool is not very important -- although clean-up presents
little difficulty, since there are no intricate passageways or
the like in the tool that might harbour solidified sealant.
The tool is manufactured by glueing or bonding together the
two blocks. Alternatively, the tool may be manufactured in
one piece using a polymeric material, cast or moulded with the
density increasing from the bottom to the top of the mould.
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The resulting composite block would be compressible and
deformable at one face, and relatively solid and rigid behind
that.
It is important that the sealing effect between the
elastically compressible foam block and the wall surface
extend right around the through-hole, i.e that there be no
channels or the like in the foam block which would allow
sealant to extrude out and escape, rather than penetrate the
crack. In fact, in an alternative embodiment, the backing-
block is provided with one or more ridges which encircle the
mouth of the through-hole, and which serve to concentrate the
compression, and hence sealing, action of the foam block onto
the wall surface.
As mentioned, an adequate seal between the nozzle of the
injector and the socket can generally be assured if the socket
is correctly designed. However, the seal at this point can be
enhanced by the use of, for example, a screw thread connection
between the nozzle and the socket, or by the use of a shape of
socket other than conical. Sometimes, the nozzle of the
injector is provided with an annular ridge, near the tip,
which can be useful for ensuring a good seal.
The consistency of the elastomeric foam material is an
important characteristic as regards the performance of the
tool. The material should not be too hard nor too soft. Good
results have been obtained when the foam has the density of
the close-packed, closed-cell foam. Such foam is not too
soft: if such foam is pressed against the wall, the foam
material "flows" into irregularities in the surface, such as
cracks. When the foam is taken away, an impression of the
shape of the crack is retained. The nature of such foam is
such that, after a few moments, the impression disappears.
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1 0
As mentioned, for the foam material to have the most
advantageous balance of conformability and rapid-rebound, the
foam material should be of the small-cell, closed-cell type.
It is contemplated in the broad scope of the invention that
the elastically deformable (compressible) material required in
the invention might be a solid, i.e non-cellular, elastomeric
material. Certainly, a very soft rubber (or plastic) might
have the required degree of conformability, and would have
almost instant rebound. However, most non-celled materials,
if soft enough to be conformable to the wall surface, would
have insufficient structural strength or toughness, and would
tend to crumble.
The use of celled foam has another advantage, which goes to
the manner of deflection of elastomeric materials. If a block
of the non-celled material were compressed locally, the
material would be subject to internal pressures which extend
more or less throughout the bulk of the material. As a
result, even a localized stress produces a non-localized or
general bulk deflection. On the other hand, when the material
is celled, the material substantially cannot transmit
deflections or stresses throughout its bulk. The material can
deflect locally, without that deflection being felt in the
bulk of the material. This property means that a block of
celled foam material is generally much more conformable to the
irregularities of a wall surface than a block of soft, but
solid, rubber.
The block of elastomeric foam material preferably should be
skinned. That is to say, the material should be manufactured
in such a manner that the cells at the surface are all closed
off, leaving the surface smooth and unbroken. The benefit of
the foam material being skinned is that the surface is thereby
rendered more durable and tear resistant. Also, the surface
is thereby rendered largely impervious to the encroachment of
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the sealant material into the cells.
The thickness of the elastomeric foam block is important. If
the foam block were too thick, the tool as a whole might be
unstable, in that a person might rock or tip the tool by
(carelessly) pressing a little off-line. When the foam block
is not too thick, the tool sits firmly against the wall when
under pressure, and really cannot be tipped or rocked. Of
course, the foam block must be thick enough that it is not
possible to push through the foam with the backing block,
thereby bottoming the backing block. A thickness of foam of
less than 6 mm, and preferably around 3 mm, has been found
satisfactory, when the block has the length and width
dimensions as mentioned above.
The foam material should have the correct combination of
properties. Thus it is not enough for the material simply to
be conformable: putty is conformable, but is not elastic, as
required in the invention. Also, celled foam can be made
rigid, but only the elastic type is suitable in the invention.
Also, a soft sponge material, like a bath sponge, being of the
open-cell type, would tend to absorb the sealant material, and
quickly become unusable.
The American Standard Test Method specification for
determining the Indentation Load Deflection of an elastomeric
cellular material, is ASTM D 1667. In that specification,
under procedure B (which is titled Compression Set), the
material is compressed to 50% of its thickness, and held for
72 hours. The compressive force is then removed, and the
thickness is measured after 30 minutes of recovery time.
Scoring is from 50 to 0, with a higher number indicating a
slower rebound.
Also, procedure D of ASTM D 1667 is titled Compression
Deflection. In this test, a block of the material is
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compressed to a standard percentage of its thickness and the
force required to achieve this compression is expressed as a
pressure on the material, measured in pounds per square inch.
Standard compressions of 25% and 50% are used.
For the purposes of the tool as described herein, the material
should be such that, in the Compression Set procedure B, the
material recovers to 35 or lower. That is to say, the
material remains no more than 35% compressed thirty minutes
after the compressive force is removed.
Preferably also, the material should be such that, in the
Compression Deflection procedure D, the 25% compression is
achieved at a loading of between 3 and 7 psi, good results
having been obtained at 4 psi.
In the invention, the best results may be expected when the
compressibility (i.e compression deflection) is high, and the
recovery (compression set) is low. Generally, however, with
closed cell elastomeric materials, materials with the higher
compressibilities tend to have the slower recovery rates.
The density of the material also is important in determining
performance. A density of 10 lbs per cubic foot (0.16 gm/cm3)
has been found to give good results.
Figs 4a,4b,4c,4d show a variation on the design of the backing
block 39, in which adequate rigidity is achieved by forming
the block in the particular shape.
Fig 5 shows the use of a rigid spigot or plug. The spigot 40
is bonded into the backing block 43, and engages a recess 45
in the wall. The complementary recesses 45 are prepared in
the wall beforehand, being spaced at suitable intervals along
the length of the crack. The recesses may be surface-levelled
later, if required, with suitable filler.
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13
A device of the type as described in relation to Figs 1 and 2
has been used to inject acrylic latex caulking to a depth of 2
cm in a crack with a width of 0.5 mm, using only finger and
hand operation of the tool, as described.
As described, the tool may be used to aid in the injection of
e.g silicon sealants, rubberised sealants, adhesives, fillers,
caulking, grouts, and anything else of a liquid or pasty
nature that is used for filling cracks.
