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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to a cushioning article, and more
particularly relates to an improved construction and method for making a
cushioning article having good comfort and support qualities with reduced
material waste. For example, in the present invention, the cushioning may
be employed in furniture seat and back cushions and headrests, and throw
cushions, or the like. The invention is particularly suited for production
of a bed pillow.
A comfortable sleep-inducing support for a person's head, such as a bed
pillow, must meet several demanding criteria. For example, the pillow must
be of a shape to conveniently receive a person's head. It must feel soft
to initial contact, while at the same time provide adequate support. It
should be air permeable to allow the body heat to be dissipated. It should
have resilience so that it can be restored to an initial shape when a
person raises his head from a pillow. At the same time, resiliency should
not be such that the pillow will "fight back" when one is attempting to
seek comfort and rest for the head. The achievement of the aforesaid
criteria in one pillow at an economical cost with readily available
material has been a problem.
In the past, comfortable pillows have been obtained traditionally by
filling a sewn case with selected down or feathers from various fowl.
Goose down was considered, for example, the most desirable. The resultant
bed pillow readily conformed to a person's head. This was accomplished in
part by compaction of the feathers, and in part by a shifting of the
filling material so as to provide the gentle cradling of the head with the
desired degree of softness, support, and selected amount of resiliency.
The pillow was capable of being returned to its original condition after
use by the simple process of being "fluffed." However, the scarcity and
high cost of feather and down has resulted in the need for an acceptable
substitute for the conventional pillow.
One approach was to attempt to utilize synthetic fibers to simulate the
natural feathers and down. In this regard, synthetic fibers, such as of
polyester polymers, were produced to provide a variety of fiber fillings
for bed pillows. The fiber filled pillow, however, had a serious
disadvantage in that the synthetic fibers did not possess the permanent
resilience which were characteristic of the feather or down. As a result,
such synthetic fiber pillows tended to matt and lose some of their
usefulness after a comparatively short period of time.
Another approach was to use foam rubber, which was developed in the late
1930's. This was accepted as an upholstery material of superior comfort
and great permanence, but in its original form, it was too firm for a bed
pillow. In the late 1940's and early 1950's, a process for making latex
foam rubber was developed (Talalay, U.S. Pat. No. 2,432,353) which was
capable of consistently producing a foam rubber of sufficient softness and
light enough density to provide a practical and comfortable pillow. As a
result, in succeeding years, latex foam rubber pillows, made in accordance
with the above invention, were utilized world-wide, partially, because of
their durability and non-allergenic characteristics. While the latex form
provided the best foam pillow, the price of the foam rubber was
sufficiently high that the industry saw the need for the use of a less
expensive material.
Flexible urethane foams, which were introduced into this country in the mid
1950's were of sufficiently low price that they began to have increasing
acceptance in the furniture cushioning industry and in foam mattresses as
a replacement for the foam rubber. While the flexible urethane foams did
not have the resilience characteristics of the latex foam rubber, the
price advantage of the flexible urethane foams was sufficient to result in
the wide spread adaption of the material for the furniture cushioning and
mattress industries. However, attempts have been unsuccessful to make a
satisfactory bed pillow by the use of such polyurethane foams.
One of the problems is that the filling of a foam pillow, whether latex or
polyurethane, does not shift as does down or synthetic fiber. As a result,
such foam pillows could not achieve stress-free cradling comfort for a
person's head partially by rearrangement and partially by compression but
rather had to rely entirely on deformation to achieve cradling comfort
which is so important for the inducement of sleep. This shortcoming of
foams in general was particularly a problem in using polyurethane foam,
making polyurethane foam generally unacceptable for use in a pillow.
One of the particular difficulties of polyurethane foam relates to the
difficulty of achieving the desired shape. The external shape of a pillow
is important, and it is well known that the proper shape for a bed pillow
is one which, in cross section in both the length and widthwise
directions, is in the form of a flattened ellipse. Such shape is
hereinafter referred to as a stereo-elliptical shape, but the production
of such shape from polyurethane foam has been uneconomical. This is
because it is extremely difficult to economically produce the desired
stereo-elliptical shape from a large block of polyurethane foam without
incurring a large amount of material waste. Moreover, automatic machinery
capable of cutting a compounded curvature has not as yet been developed.
As a result, multiple operations are required to even approximate the
desired shape of the pillow.
A second problem with use of the polyurethane flexible foam material has
been in achieving the desired balance between comfort and support. As
employed herein, the terms "comfort" or "softness" mean the ability of the
cushioning structure to deflect at the surface and conform to the body
shape. This prevents a concentration of pressure on the body. The term
"support" employed herein means the ability of the cushioning structure to
hold the body in the relaxes position and allow free body movement by
providing a firm base to push against. Support minimizes stress on the
joints. The desired comfort or softness for a pillow for sleeping is
provided if the pillow deflects 25% of its original height when a
compressing load of 3 to 7 lbs. distributed over a flat plate 50 sq.
inches in area is vertically applied to it.
While the pillow should be soft to initial contact, it still must be able
to provide adequate support for the head. One parameter for such support
is that the pillow would have sufficient resistance that, in order for the
pillow to be compressed 65% of its original height, a load is required
which is 21/2 to 3 times the load needed to compress it 25%.
The aforesaid support, which can also be referred to as the resistance of
the pillow to "bottoming" is usually measured as the load at 65%
deflection. The desired softness-to-comfort relationship can be expressed
as the ratio of load at 65% deflection to the load at 25% deflection. Such
ration, called SAG or SAC factor, provides an approximate slope of the
curve above the usual softness reference point (i.e., 25% deflection).
Such ratio defines not only the characteristic shape of the
compression-deflection curve of the flexible foam material but also
provides substantial information about the comfort providing capability of
the material when employed for cushioning a person's head.
Conventional polyurethane foam did not have the desired load deflection
characteristics. SAG factors at 1.5 to 1.9 were representative of the best
polyether urethane foams based on polyoxypropylene ethertriols of 3,000 to
4,000 molecular weight and an 80-20 isomer ratio of toluene diisocyanate,
as compared to SAG factors of 2.8 to 3.2 for soft latex foam rubber.
Recently, high resiliency (HR) foams have been developed. These foams are
based on high primary hydroxyl containing polyether triols and polymeric
isocyanates. Because of the markedly different polymer structure, foams of
this type have quite different cushioning properties from the conventional
urethane foams. The modulus of the new HR materials is much lower for a
given density, and their compression deflection curve more closely
resembles that of latex foam rubber. Such HR foams have SAG factors of 2.5
to 2.8. However, such new materials have a disadvantage in that the HR
foams are considerably more costly on the board foot basis then
conventional polyurethane foams.
Another important aspect of the sleep inducing pillow is that it must have
a high degree of air permeability. In other words, it must allow the body
heat to be readily dissipated as the person's head changes position and
induces a pumping action in the pillow. Since all foams are insulating
materials, the body heat cannot be readily removed by conductance.
Polyurethane foam presents a particular problem in this regard, because of
the relatively lower air permeability of polyurethane foam compared to
that of the latex foam rubber. Many urethane formulations even produce a
partially "hermetic" foam (partially containing closed cells) which has to
be "crushed" by intensive rolling or pounding to remedy its tendency to
feel sluggish. This is notably the case when attempts are made to produce
a very soft foam, e.g., of a ILD below 8 or 10 lbs., needed to make a bed
pillow.
One of the approaches has been to produce a somewhat firmer foam and to
"convolute cut" it. This is done by distorting the material, in sheet
foam, between rolls which are studded over their entire surface with
pyramidal projections in such a manner that the projection of one roll
corresponds to the absence of a projection on the other roll. A band knife
arranged in parallel to the axis of the rolls and close to the nip on the
exit side of the compression-distorted material cuts the material into two
matching layers which have over their entire surface a convoluted
configuration. As an example, a two inch thick pad may be cut into two
convoluted layers, where the peaks are 11/2" high and the valleys 1/2".
Convolute cut material indeed possesses a lower ILD than the material from
which it was cut. However, because of the concentration of stress on the
tips of the pyramids when compressive and especially dynamic load is
applied, the convoluted material tends to soften and collapse, i.e., lose
height.
In the present invention, it has been found that an adequate reduction in
initial ILD (an adequate increase in initial softness) for the creation of
a satisfactory bed pillow can be accomplished by perforating the
polyurethane material, rather than by convoluting it. Preferably, the
holes (perforations) have a cross-sectional diameter between 1/8" and 1/2"
and an equidistant spacing from 3/4" to 11/2". By this arrangement, the
percentage of surface area that has been removed is not more than 30%. In
the invention, it has been found that perforation in the above manner not
only (a) increases the air permeability of the pillow, and (b) breaks up
the surface tension of the foam blank in such a manner that deformation of
the pillow under localized load does not extend to the entire surface, (a
very important feature in reducing "fight back") but also permits to lower
the ILD of the material without seriously affecting the ability of the
material to withstand dynamic loading. Thus, in comparing a convoluted and
a perforated foam by subjecting them to the Dynamic Fatigue Test, ASTM
Designation D 1564-71, Suffix H, Procedure 8 (Dynamic Fatigue by the
Roller Shear at Constant Load), it is found that after 20,000 cycles a
convoluted Polyether urethane foam with an original ILD of 6 to 9 lbs. has
lost 13% of its height, while a perforated material has lost less than 6%.
SUMMARY OF THE INVENTION
The present invention provides a new and novel cushioning article, and more
particularly relates to a bed pillow which combines all of the essential
requirements for optimum application, including good comfort and support
properties, good air permeability (breathability), absence of "fight
back," and relative freedom from dynamic fatigue. The article of the
present invention can be efficiently produced by readily available
equipment in quantity, with a minimum of waste. More particularly, the
cushioning article of the present invention comprises a multi-layered
construction including, in combination, layers of conventional and
high-resiliency polyurethane foam material. The cushioning article
utilizes a plurality of predetermined spaced aperatures of selectively
reduced diameter in at least certain of the layers. The cushioning article
is made from a strip like piece of such material and has a step-wise
configuration of predetermined progressively reduced width-wise dimension
disposed toward the interior of the article with the outer layer and/or
layers being secured together along the associated periphery to form such
stereo-elliptical shape.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a generally perspective view illustrating a block of material
having a reduced step-wise construction of the type which may be employed
in one form of making the cushioning article of the present invention;
FIG. 2 is a top plan view of the block of material of FIG. 1;
FIG. 3 is an enlarged fragmentary view illustrating one embodiment of the
pin coring system of the present invention;
FIG. 4 is an enlarged fragmentary view illustrating another embodiment of
the pin coring system of the invention;
FIG. 5 is an end elevation view illustrating a single strip-like piece of
material wrapped radially in one embodiment of making the cushioning
article;
FIG. 6 is an end elevation view illustrating another step in forming the
cushioning article;
FIG. 7 is an end elevation view illustrating one embodiment of the pin
coring system in one form of the invention;
FIG. 8 is a generally perspective view of the finished cushioning article
in the form of a pillow made in accordance with the invention;
FIG. 9 is an enlarged fragmentary section view illustrating another
embodiment of the pin coring arrangement;
FIG. 10 is a top plan view illustrating another embodiment for producing
the strip-like pieces for making the cushioning article in accordance with
the invention;
FIG. 11 is a generally perspective view illustrating another embodiment for
making the cushioning article of the present invention;
FIG. 12 is an end elevation view illustrating another step in making the
cushioning article of FIG. 11; and
FIG. 13 illustrates the final step in making the cushioning article in
FIGS. 11 and 12.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring again to the drawings, and particularly to FIGS. 1 to 8, there is
illustrated one embodiment for making the cushioning article, such as a
bed pillow, designated generally at 2 in FIG. 8. In the form shown, the
article 2 is made from a block 4 (FIG. 1) of open-cell polyurethane foam
material. The block 4 may be produced on a continuous flexible foam slab
line, by pouring on a moving conveyor, known in the art. As shown, the
block 4 has a step-wise configuration of reduced transverse dimension
defined by polygonal, such as rectangular, sections 6, 8, 10 and 12. To
produce a bed pillow measuring 25" .times. 161/2", having a maximum
thickness at the crown (of 7") and elliptical cross-section, both in the
length and the width-wise dimensions, the respective sections 6 to 12
preferably have dimensions of 181/2" .times. 10" (AB), 211/2" .times. 26"
(CD), 241/2" .times. 32" (EF), and 271/2" .times. 38" (GH), as best seen
in FIG. 2. This provides an overall length of approximately 106" which
diminishes in width-wise dimension from 271/2" to 10" in respect to the
longitudinal center-line of the block. In making the pillow, after
maturing and crushing, to increase the inter-communication of the cells,
the block 4 may be horizontally sliced into approximately 1" thick sheets,
as illustrated in doted-lines S of FIG. 1. In this form, the article may
be produced by rolling one of the sliced sheets, as at 14, FIG. 6, upon
itself into a generally flattened elliptical shape and securing, such as
by cementing, the outer layer to itself on three sides along the article's
outer central periphery or equator.
More specifically, and with reference to FIG. 5, the strip-like piece 14
may be radially wrapped on a circular rotating mandrel (not shown) which
may have, for example, a diameter of 10". In carrying out this operation,
the section 6 forms the inner equatorial plane, the section 8 the first
interior layer 16, the section 10 the second interior layer 18, and the
section 12 the outer layer 20. By this arrangement, this dimensional
relationship provides the geometric result that as the diameter of the
ellipse is increased 2", the circumference is increased by approximately
6". During this wrapping operation, each succeeding layer overhangs as at
7, 9, and 11, the underlying one by approximately 11/2" on each side.
After the outer layer has been secured to itself, such as by cementing,
heat sealing or the like, the rolled-up blank is removed from the mandrel,
such as by collapsing or deflating it. This cementing is illustrated, as
at 22, in FIG. 5, to give the concentric disposition of the layers, as
shown. To facilitate forming of the seam along the edge, as at 24, the
edge may be beveled or chamfered prior to cementing to provide the
finished beveled edge, as at 26 in FIG. 8. A small amount of adhesive
material may then be sprayed into the internal diameter of the roll and
the concentric circular structure collapsed in a manner that places the
outer seam at the equator, or at the generally longitudinal plane of the
article. Thus, collapsed, there is provided a radially wound structure,
which, if viewed from the end, has the desired stereo-elliptical shape.
Minor stresses built into the body will relax over a period of time. The
length-wise dimensions of the section H are now secured to themselves by
cementing or heat sealing at the equator, as at 28 of FIG. 8, providing a
smooth elliptical shape in the direction perpendicular to the first
mentioned ellipse as seen in FIG. 6.
In the invention, the sections 6 and 8 (FIG. 1) and A,B-C, D (FIG. 2) only
of the block 4 may be made of a high resilient (HR) polyurethane foam,
while sections 10 and 12 (FIG. 1) and E, F-H, G (FIG. 2) may be made of
conventional polyurethane foam material. The (HR) material may have the
typical formulation indicated in table A, as follows:
TABLE A
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Polyoxypropylene Triol, 60% Primary Capped,
Molecular weight 4,500 to 6,000
100 parts
Aromatic amine (e.g., duPont LD-813)
3 to 5 parts
A di-methyl ethanol amine catalyst (such as
Propamine A; T.M. Lencro Chemicals)
0.5 parts
A triethylene diamine catalyst (such as
DABCO 33 LV; T.M. Houdry Process Corp.)
0.5 parts
Silicone DC 200/5 (T.M. Dow Corning-Silicone
oil, 5 centistokes viscosity)
0.4 parts
Water 2 parts
A "mixed" or a "crude" isocyanate (such as
Desmodur 44 VT-Index 100; T.M. Mobay
Chemical Co., or Hylene TCPA-105 Index;
T.M. duPont) 34.2 parts
Trichlorofluromethane 15 to
*sufficient to produce with chosen
20 parts*
water level an open-cell foam of 1.1 to
2.0 lbs. per cubic foot density and a
mean Indent Load Deflation (ILD) of 3 to 8
pounds at 25% and SAG factor in excess of
2.5
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In the invention the material contained in the stepwise progressively
reduced 1" thick strip-like piece 14 (with the given dimensions)
constitutes approximately 2574 cu.inches or 17.88 board feet (one board
foot being one square foot, one inch thick). By comparison, to carve a
pillow of the same size from a solid block of polyurethane foam (e.g., hot
wire cutting, buffing, distortion-cutting or profile cutting) there would
be required a starting block measuring at least 25" .times. 161/2" .times.
7" thereby containing approximately 20 board feet of material. In such
case, it is probable that in order to obtain a satisfactory bilateral
profile, at least 5% more material would be needed, i.e., 21 board feet.
It is apparent, therefore, from the present invention that a more
economical method is provided requiring approximately 15% less material to
obtain a pillow of comparable shape and size. As will be seen, the
"carving" of a compound curvature into a soft foam is at best a very
difficult task. It required not only complex machinery, but multiple
operations. The widely used cutting of profiles with a hot wire is not
readily applicable because of the residual smell.
In the invention, the step-wise reduced dimension strip-like piece can be
economically obtained in a number of manners from a large continuously
poured "bun" of polyurethane foam. For example, assuming that the "usable"
thickness (or height) of the "bun" is 30 inches, then the sections 6, 8,
10 and 12 can be cut to provide individual 30" high blocks which can be
cemented together to form the "masterblock" illustrated in FIG. 1 which,
in turn, can be sliced on a band saw into 1" thick sheets. Alternatively,
if it is desired to have a lesser number of cemented joints, the thick bun
can be sliced first into 1" sheets of maximum size, and the step-wise
tapered sections cut from such sheets with very little waste by
alternating the direction of taper, as seen in FIG. 10. In this case, the
waste area, as at 30 and 32, represents only a small fraction of the
usable material area.
As a further example, a pillow 25" .times. 161/2" .times. 7" may be
produced in the same manner as aforementioned, except that the "bun" prior
to cutting into blocks 4 or slicing into 1" layers is reticulated to yield
a more open-pore, viz., a more air-permeable material. This may be
accomplished, (e.g., in accordance with U.S. Pat. No. 3,297,802 or
3,175,030) by permeating the foam with a flame explodable mixture of fuel
and oxygen, and sparking it to "blow out" the window membranes between the
cells in the foam.
In another example, the pillow may be produced as aforementioned, except
that one or more of the sections 6, 8, 10 and 12, e.g., after slicing is
provided with a plurality of corings (perforations) formed in the
"broadside faces" 24 and 36 (FIG. 8) of the article. Preferably, the cores
have a cross-sectional diameter between 1/8" and 1/2" and between
approximately 3/4" to 11/2" equidistant spacing. By this arrangement, the
"percentage void area" of the broadside faces is not more than 30%. The
"percentage void area" of the perforated surface is derived by dividing
the area of the surface removed as the result of the perforation by the
area of the surface prior to perforation and multiplying the quotient by
100. As shown, the equatorial area, as at 40, of FIG. 8, may remain
un-perforated if desired. The result of the perforation is two-folds: (A)
to increase the air-permeability of the pillow, and (b) to break up the
surface tension of the foam blank in such a manner that deformation of the
pillow under a localized load does not extend to the entire surface. By
this arrangement, the comfort characteristics of the foam pillow are
enhanced. An added advantage is that a polyurethane pillow with a
perforated surface can be slightly "crowded" into a pillow casing without
producing unsightly surface wrinkles.
Polyurethane foams, especially when made with aromatic isocyanates tend to
yellow on the surface when exposed to the U.V. component of the light
spectrum. To reduce this tendency, which detracts from the esthetic appeal
of the product, the polyurethane material used in this embodiment may have
its outer layer protected with an U. V. light absorber, alone or in
combination with a synergist. As an example, one part each of benzoic acid
hydrazide; tetrakis [methylene 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)
proportionate] methane (Irganox 1010-T.M. Ciba-Geigy): and Tinuvin 328
(T.M. Ciba-Geigy for a substituted benzotriazole) can be used for each 100
parts of polyurethane foam formulation remaining after the reaction. The
additive can be dissolved or finely dispersed in one of the components of
the formulation, or it can be applied by spraying to the surface of the
fabricated pillow. In any case, it is sufficient to associate the additive
only with the outer layer or surface of the pillow.
In FIGS. 11 to 13, there is illustrated another embodiment for making the
cushioning article, designated generally at 50 in the present invention.
In this form, an open-call polyurethane strip-like piece 42 is provided in
slab form in a polygonal, such as rectangular, configuration. In this
form, the strip had dimensions of approximately 241/2" .times. 33" .times.
1.5" to which was secured adjacent one end an insert member of polygonal,
such as rectangular, configuration having dimensions of 111/2" .times. 20"
.times. 3". The insert member 44 was adhesively secured, as at 46, to the
piece 42, e.g., by spot-cementing the same to the piece 42 adjacent one
end so as to provide approximately 2" margins, as at 48, on three sides
thereof. The member 44 preferably has a thickness equal to or less than
the doubled thickness of the piece 42. The strip-like piece 42 was then
wrapped (clockwise, FIG. 12) upon itself so as to be disposed in covering
relation over the insert member 44. Thus disposed oppositely disposed
edges 51 and 52 (FIG. 11) are brought into face-to-face relation and
pinch-cemented together, whereas, the confronting end edges, as at 54 and
56, are pinch-cemented together to provide a smooth joint, as at 58, (FIG.
13), to provide the finished cushioning article 50. In this form, as the
piece is wrapped upon itself, the confronting interior corners, as at 60,
62, 64, and 66, are yieldably collapsed due to the softness of the
material giving a generally elliptical (cross section) to the finished
article. Hence, the article is defined by a closed bight portion 68 at one
end with a rounded joint end 58, as aforesaid. As indicated, the insert
member 44 may be spot-cemented, as at 46, to the confronting interior
surface of the piece 42, whereas the entire periphery of the side edges 50
and 52, as well as that of the end edge 56, may be lightly sprayed with an
air setting cement to provide the desired edge pinch-cemented joints on
three sides of the article.
Either the piece 42 or the insert member 44 or both may be made from the
high resiliency (HR) polyurethane material, as aforesaid. However, in this
form the insert member 44 may be made of high resiliency polyurethane,
whereas the piece 42, as well as sections 6 and 8, may be made from a
conventional polyether polyurethane foam which is perforated or
unperforated, as desired. In such case, the foam may have a typical
formulation as set forth in Table B, as follows:
TABLE B
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Comment Parts by Weight
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Polyol (Trifunctional)
100.0
Toluene Diisocyanate 46.0
Organo Tin Catalyst 0.4
Silicone Surfactant 1.0
Tertiary Amine Catalyst
0.2
Water 2.0 - 3.5
Monoflurotrichloromethane
10.0 - 15.0
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A conventional polyether foam suited for bed pillow application may have a
density of 0.9 to 1.0 pounds per cubic foot; an indent load deflection
(ILD), as measured in accordance with ASTM D-2406-68, of 4 to 7 pounds;
and a ratio of 65% deflection load to 25% deflection load (SAG factor) of
1.7 to 1.9.
In either case, the piece 42 may be provided with a pin core apertures, or
perforations 70, which, as illustrated in FIGS. 12 and 13, extend
completely through the piece. In this case, the pin cores may have the
same dimensions and "percentage void area" relationship as described in
connection with the article illustrated in FIG. 8. Further, it is
recognized that the pin cores 38 and 70 may be disposed in aligned
relation with one another, as seen in FIGS. 7 and 12, or they may be
disposed in a staggered pattern, as seen in FIG. 9, so as to provide the
desired "percentage void area." As seen in FIGS. 6 and 7, for example, the
pin cores 38 may be provided in the outermost layer 20, or may be provided
in aligned relation in all of the superposed layers so as to communicate
with the cavity 39 (FIG. 7) defined by the closed structure. It has been
found that | | |
