Apparatus for distributing a foamed composition on a substrate

An apparatus is disclosed for continuous distribution of a latex or urethane foam composition on a movable substrate to produce a foamed sheet material such as a foam backed carpet. The distribution apparatus comprises a generally cylindrically shaped rotatable member and at least two attached distribution means which may take the form of either modified doctor rolls or modified doctor blades. The distribution surface of each of these distribution means may differ and may be either smooth or patterned with a variety of grooves or serrations thereby providing means for producing foamed sheet materials with surfaces which are either planar or patterned with ridges and valleys. Means are also provided to readily change the thickness of the distributed foam and for oscillating the distribution apparatus to produce a surface with wavy as opposed to linear patterns of ridges and valleys. All of these operations may be accomplished without interrupting the continuous process.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the manufacture of foamed sheet material 
and pertains particularly to an apparatus and method for distributing a 
foamed fluid composition on a movable substrate to produce a foamed sheet 
material. 
2. Discussion of the Prior Art 
It is known to apply a viscous foamed fluid composition to a movable 
substrate and then, as necessary subsequently, to dry and cure the foamed 
composition. Such processes are used to produce foamed sheet materials, 
such as foam backed carpet and foam underlays for carpets. The foamed 
fluid composition may be a latex or a urethane. Previously such foamed 
compositions have been applied to the substrate and then distributed 
across the substrate by methods well known to the art using doctor blades 
or doctor rolls. It is desirable at times to provide a surface pattern on 
the foamed sheet material so produced. In the past a second step was 
necessary to produce this pattern since the doctor blades or rolls had 
smooth distribution edges or surfaces, thereby producing a foamed sheet 
material with a planar surface. To perform this second step, a variety of 
embossing techniques were developed, such as that taught in U.S. Pat. No. 
3,210,447. In addition to being two-step processes requiring a high degree 
of control and coordination between the steps, all of these techniques had 
the added disadvantages of design inflexibility and high tooling cost in 
the embossing apparatus and wastage of the foamed composition where it was 
compressed by the embossed indentations. 
An improved method and apparatus for producing patterned foam sheet 
materials were developed in U.K. Pat. No. 1,241,800, wherein the 
distribution and the pattern forming steps were combined. A series of 
doctor blades with lower edges having a variety of notches, cut-out parts, 
or protrusions were used to distribute the foamed composition and 
simultaneously produce a pattern of ridges and valleys on the surface of 
the foamed sheet material. A wide variety of patterns could be produced 
with tooling costs substantially lower than with embossing techniques and 
without wasting the foamed composition in embossed indentations. However, 
the specification provided no clear teaching on the mechanism used for 
moving the blades into and away from the distribution position nor on the 
methods used for mounting the blades. Additionally, there was no teaching 
on methods which could be used for substituting one or more blades for 
blades already mounted on the apparatus without stopping the process to 
make these substitutions nor was there any teaching on distribution means 
other than doctor blades. 
The present invention is an improvement upon this prior art and seeks to 
overcome the limitations in its teachings. It is an object of the present 
invention to provide an improved apparatus and method for distributing a 
foamed fluid composition on a movable substrate in a one-step continuous 
operation producing a sequence of foamed sheet materials whose surfaces 
may be planar or variously patterned, wherein the distribution means and 
the pattern forming means are combined and may be either a doctor blade or 
a doctor roll and wherein the distribution means may be readily changed 
without interrupting the continuous process. 
SUMMARY OF THE INVENTION 
The present invention provides an apparatus for distributing a viscous 
foamed fluid composition which has been applied to a movable substrate 
which comprises a rotatable member and at least two distribution means 
wherein said member is a tubular roll with a generally cylindrical shape, 
means cooperating with said member to readily attach and detach said 
distribution means, said distribution means being attached to said member 
in a radially outwardly extending manner so that the most radially distant 
surface of each of said distribution means is a distribution surface for 
distributing said composition on said substrate, said distribution means 
being attached to said member so that at any given time the distribution 
surface of only one of said distribution means is in position for 
distributing said composition on said substrate, each of said distribution 
surfaces imparting essentially the final surface pattern to said 
composition when used for distributing said composition, said member being 
positioned above and extending substantially across the surface of said 
substrate normal to the direction of travel of said substrate, means 
cooperating with said member to raise and lower said member perpendicular 
to the surface of said substrate, means cooperating with said member to 
rotate said member about the central axis of said member and normal to the 
direction of travel of said substrate through an angle of one or two times 
360.degree. divided by the number of said distribution means, locking 
means cooperating with said member to prevent rotation of said member, and 
means cooperating with said member to oscillate said member from side to 
side normal to the direction of travel of said substrate. 
The present invention also provides a method for distributing a viscous 
foamed fluid composition on a movable substrate which comprises applying 
said composition to said substrate, passing said substrate beneath an 
apparatus as hereinbefore defined, and contacting said composition with a 
distribution surface of said apparatus thereby producing a foamed sheet 
material. 
Preferred embodiments of the present invention are detailed more fully in 
the following description when considered in conjunction with the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1 a substrate 2 is delivered from a feed roll 1 to pass beneath a 
foam supply nozzle 3, the foam supply nozzle being supplied from a 
reservoir 4 with a foamed fluid composition 5 which may be a latex or a 
urethane. The substrate bearing the foamed composition passes beneath a 
distribution apparatus which comprises a rotatable member 6 and at least 
two attached distribution means 7 which distribute the foamed composition 
on the substrate to form a foamed sheet material 8. This foamed sheet 
material may then pass through other pieces of equipment such as a heating 
oven 9 to dry and cure the foamed portion before being taken up by the 
takeup roll 10. The rotatable member 6 is a tubular roll with a generally 
cylindrical shape which is preferrably made from nickel or chrome plated 
carbon steel. A small shaft 11 protrudes from each end of the central axis 
of the rotatable member. This shaft is the point of attachment which 
allows the rotatable member to cooperate with various means to move the 
member or to prevent it from moving. Thus, each end of the shaft is 
supported by a set of bearings 13 which will allow the shaft to rotate 
about its axis and also oscillate parallel to the surface of the 
substrate. The sets of bearings are attached to a supporting frame 12. 
FIG. 1A shows means cooperating with the rotatable member 6 to rotate the 
member about its central axis and normal to the direction of travel of the 
substrate through an angle of one or two times 360.degree. divided by the 
number of distribution means attached to the rotatable member. A 
convenient means is motor 14 which is coupled to the shaft 11 by a 
flexible shaft 15. Also shown is a braking means 16 which cooperates with 
the rotatable member to prevent its rotation by locking shaft 15 in 
position whenever desired. The motor 14 is supported by a frame member 17 
which is connected to supporting frame 12. Frame 12 is constructed in any 
convenient manner so that it may be raised or lowered perpendicular to the 
surface of the substrate, thereby providing means cooperating with the 
rotatable member to raise and lower said member. Means cooperating with 
the rotatable member to oscillate said member from side to side normal to 
the direction of travel of the substrate are also shown in FIG. 1A. A 
convenient means is a cylinder 18 having a movable piston 19, operated for 
example by hydraulic pressure, which operates on shaft 11 through shaft 20 
whereby the rotatable member 6 with its attachments is movable through 
bearings 13 so as to provide the oscillating motion. 
The distribution apparatus shown in FIG. 1 is in the form of one of the 
preferred embodiments of this apparatus. FIGS. 2 and 3 show two views of 
this preferred embodiment which is a modified doctor roll comprising a 
cylindrical rotatable member 43 of circular cross section having a number 
of attached distribution means comprising longitudinal arcuate sections 
which are of about equal length to and concentric with the rotatable 
member and whose inner surfaces conform with the external surface of the 
rotatable member 43. These sections, hereinafter referred to as sleeve 
members, may vary in number from at least 2 to about 4 and are preferrably 
made from nylon or stainless steel. FIG. 2 shows the preferred embodiment 
of 3 sleeve members 40, 41 and 42. FIG. 3 shows that the sleeve members 41 
and 42 are attached to the rotatable member by suitable means 45 so that 
any sleeve member may be readily attached to or detached from the 
rotatable member. The preferred means for attaching the sleeve members are 
bolts which screw into corresponding threaded taps in the rotatable 
member. Thus the sleeve members are attached to the rotatable member in a 
radially outwardly extending manner so that as shown in FIG. 1, their most 
radially distant surface may be used as a distribution surface for 
distributing the foamed fluid composition on the substrate. The rotatable 
member should be rotated to a position as shown in FIG. 1 so that at any 
given time the distribution surface of only one of the sleeve members 
40-42 is in position for distributing the foamed composition on the 
substrate. 
It is often desirable to produce a foamed sheet material which has a 
surface pattern. This can be accomplished using the preferred embodiment 
of the distribution apparatus shown in FIGS. 2 and 3 wherein the 
distribution surfaces of the sleeve member distribution means are grooved 
parallel to the direction of travel of the substrate. Two preferred 
embodiments of grooved sleeve members are shown in FIG. 3. Sleeve member 
41 has grooves which in longitudinal cross section are separated repeating 
uniform radially inwardly extending arcs. Sleeve member 42 has grooves 
which in longitudinal cross section are separated repeating uniform 
radially inwardly extending truncated "V" indentations. Thus, each of the 
distribution surfaces may be dissimilar. Since the distribution surface of 
the sleeve member which is being used to distribute the foamed composition 
will of necessity impart the final surface pattern to the foamed sheet 
material, different distribution surfaces will produce different surface 
patterns. A sleeve member with a smooth distribution surface may be used 
to produce a planar foamed sheet. 
During the distribution process, the distribution surface of the sleeve 
member being used to distribute the foamed composition may become fouled 
by foamed material drying upon it over a period of time. When attached to 
the rotatable member, a new sleeve member with a clean distribution 
surface and the same groove pattern as that which has become fouled may be 
rotated quickly into place by rotating the central shaft 44 of the 
rotatable member shown in FIGS. 2 and 3 without stopping the distribution 
process. The fouled surface may then be cleaned or the entire sleeve 
member may be detached, cleaned and reattached, or replaced by a new 
sleeve member. Similarly, if it is desired to change the surface pattern 
which is imparted to the foamed sheet material, the rotatable member may 
be quickly rotated to bring a new sleeve member into position having a 
differently grooved distribution surface. A smooth distribution surface 
may replace a grooved surface or vice versa, thereby providing means to 
change between planar and patterned surfaces for the foamed sheet whenever 
desired without stopping the overall process. 
The thickness at which the foamed composition is distributed may be changed 
using the preferred embodiment of the distribution apparatus shown in 
FIGS. 2 and 3 by raising or lowering the rotatable member as already 
described in connection with FIG. 1. The central shaft 44 shown in FIGS. 2 
and 3 is the point of attachment as described in relation to the shaft 11 
shown in FIG. 1. However, it should be noted that side to side oscillation 
of this modified doctor roll distribution apparatus is not recommended. 
Because the large area of contact between the distribution surface and the 
foamed composition imparts undesirably irregular patterns to the surface 
of the foamed sheet material. 
Side to side oscillation of the distribution apparatus may be used however 
with the second preferred embodiment of a suitable distribution apparatus 
shown in FIGS. 4 and 5. This embodiment is a modified doctor blade 
distribution apparatus comprising a cylindrical rotatable member 50 of 
generally circular cross section having a number of attached blade 
distribution means comprising members of length about equal to the 
rotatable member. These blade members may vary in number from at least 2 
to about 6. FIG. 4 shows the preferred embodiment of 4 blade members 51, 
52, 53 and 54. FIG. 4 shows that these blade members are attached to the 
rotatable member 50 by series of bearing brackets 55, 56, 57 and 58. The 
enlarged view in FIG. 6 shows the means of attaching one of the series of 
brackets 56 to the rotatable member 50 and to the blade member 52. The 
rotatable member is flattened somewhat at the surface 50A where it is 
joined to the bearing bracket by any convenient means such as a cap screw 
60 which is screwed into a hole 61 which has been drilled and tapped into 
the rotatable member. The blade member is attached to the bearing bracket 
by any convenient means such as a countersunk flat head machine screw 62. 
The blade members may be readily attached to and detached from the 
rotatable member using the series of these screws and bearing brackets as 
shown in FIG. 5. The blade members are attached in a radially outwardly 
extending manner as shown in FIGS. 4 through 6 so that the most radially 
distant surface of each may be used as a distribution surface. They are 
spaced roughly equidistant from one another around the rotatable member so 
that easy access to the attachment screws may be obtained and so that at 
any given time the distribution surface of only one of the blade members 
may be in position for distributing the foamed composition on the 
substrate. 
As with the embodiment shown in FIGS. 2 and 3, the embodiment shown in 
FIGS. 4 and 5 may be used to produce foamed sheet materials with either 
planar or patterned surfaces. The latter may be produced by using blade 
member distribution means wherein the distribution surfaces are serrated. 
FIG. 5 shows two preferred embodiments of the serrated blade members. 
Blade member 53 has serrations which are separated repeating uniform 
radially inwardly extending arcs while blade member 51 has serrations 
which are separated repeating uniform radially inwardly extending 
truncated "V" indentations. Foamed sheet materials with planar surfaces 
may be obtained using a blade member with a smooth distribution surface. 
The operation of this embodiment of the distribution apparatus is 
essentially the same as that described for the first preferred embodiment. 
The central shaft 59 shown in FIGS. 4 and 5 is the point of attachment 
which allows the rotatable member to cooperate with the means for raising 
or lowering, rotating and locking, and oscillating the rotatable member. 
Oscillation of the rotatable member when using blade member distribution 
means gives a wavy pattern to the surface of the foamed sheet material. As 
with the first embodiment the thickness of the foamed sheet material may 
be altered by raising or lowering the distribution apparatus. Blade 
members may be changed readily by rotating the rotatable member. Blade 
members may be easily replaced or removed for cleaning. All of these 
operations may be carried out in a simple and straightforward manner 
without stopping the process and this invention therefore provides a 
significant advantage over the prior art to manufacturers of foamed sheet 
materials. 
The blade members referred to in FIGS. 4 and 5 may be manufactured of 
suitable material such as stainless steel or a synthetic material such as 
Nylon. Depending upon the type of guage of the blade, it may deflect 
during use. Thus, the number of spacing of the brackets should be 
sufficient to prevent or minimize such deflection. 
In describing the present invention the rotatable member has been described 
as being cylindrical or generally cylindrical in shape. The 
cross-sectional shape of the rotatable member is not an essential feature 
of the present invention. The rotatable member could have any convenient 
cross section such as oval, square, hexagonal. However, the shape must be 
such that the distribution surface of either the sleeve or the blade 
member distribution means must be the most radially distant part of the 
distribution apparatus from its axis of rotation. The preferred embodiment 
is a rotatable member with a cross section which is circular or nearly 
circular. 
The substrate used in accordance with the present invention is preferably a 
carpet which may be tufted or woven. Other substrates may be matted 
materials such as jute, or a variety of non-woven materials such as felt, 
paper, scrim or rayon diaper stock. 
The preferred foamed fluid compositions for use in the present invention 
are a foamed styrene-butadiene synthetic rubber latex or a polyurethane 
foam. The use of the invention is illustrated by the following example. 
All parts and percentages are by weight unless otherwise specified. 
EXAMPLE 1 
This Example shows the use of styrene-butadiene latex in a no-gel spread 
foam recipe for a carpet backing in conjunction with the present 
invention. The composition of the material to be foamed is given in the 
following Table 1: 
TABLE 1 
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Latex (Blend of 95 parts styrene- 
butadiene latex containing 31% 
styrene, with 5 parts polystyrene latex) 
100.00 
Sodium lauryl sulfate 0.5 
Disodium n-octyldecylsulfosuccinimate 
5.0 
Curing paste.sup.1 5.9 
Calcium carbonate filler 
200.0 
Tan colour 0.5 
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.sup.1 A premixed composition which comprises: sulfur, 1.65 parts; zinc 
oxide, 1.25 parts; ethyl zimate, 1.00 part; zinc mercaptobenzothiazole, 
1.25 parts; diphenylamine acetone reaction product, 0.45 part; butylated 
reaction product of pcresol and dicyclopentadiene, 0.30 part. 
Water was added to bring the total solids content of the above to 78.5% and 
the composition was then foamed in a Hobart mixer to a cup weight of 190 
g/l. It was spread onto a tufted carpet substrate to produce a foam backed 
carpet. The distribution means used was the blade member shown in FIG. 7 
which was used in conjunction with the distribution apparatus shown in 
FIGS. 4 and 5. Dimensions of this blade member 70 were: a=0.5 in., b=0.125 
in., c=0.1875 in. The distance d between the blade member 70 and the 
carpet substrate 71 was 0.125 in. The foam backed carpet which was 
produced after drying and curing under a bank of infrared lamps for 1 
minute and then in a 275.degree. F. oven for 30 minutes is shown in FIG. 
8. Note that because of some unavoidable spreading of the foam, the 
surface pattern of the foam backing 80 on the carpet substrate 81 was not 
identical to the serrated distribution surface of the blade member 70 
shown in FIG. 7. The dimensions of the finished carpet shown in FIG. 8 
were: e=0.125 in., f=0.25 in., g=0.625 in. The effective thickness of the 
foam backing is f while the minimum thickness is e.