Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
This invention relates to decorative sheet-type covering
material and especially to a method for preparing suitable
substrate for such material by sealing a fiber mat or web of
open structure.
Decorative, flexible sheet-type covering materials such
as wall or floor coverings are well known. Frequently, such
coverings involve the use of a chemically blown foamable plastic
applied in a liquid state to a substrate. The foamable liquid
is then gelled, frequently printed with a design, and expanded
by heat to e.g. three times its original thickness. Conventional
use of such chemically foamed material is described for instance
in United States Patent 3,458,337 and United States Patent
3,293,094.
While the use of chemically foamed plastic over
substrates in the production of sheet covering materials is
well known and has been extensively practiced, the resulting
products have not always been entirely satisfactory. Where
porous substrates or irregular substrates have been used,
results have been less than satisfactory since penetration of
the foamable liquid coating into the supporting substrate
fre~uently results in magnified surface distortions in the
finished product. This is especially noticeable where printed
patterns are formed on the foamed layer or are printed onto
an unfoamed layer prior to foaming of the layer.
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The use of non-foamable material for sealing and coating
a porous or irregular substrate has been generally unsatisfactory
due to penetration of the coating material into the openings in
the porous substrate.
In addition to chemically foamed plastics of the type
mentioned above, mechanically foamed plastics in which air or
other gas is introduced into the plastic as by beating or other
forms of mechanical aeration are well known, as exemplified
for instance in United States Patent 3,511,788. Such mechanically
foamed plastics have been suggested for a variety of purposes
such as in very thin layers for application to a variety of
substrates as suggested in the above-mentioned Patent 3,511,788.
Such foams have also been utilized as backing for sheet covering
materials, especially flooring to provide resiliency under foot.
It is also quite common in the flooring industry to
make an embossed foam product either by use of chemical means
such as suppresent inks, etc., in the manner taught by the
above-mentioned United States Patents or by mechanical embossing
of the foamed layer or completed product. Mechanical embossing
is a well known technique as exemplified for instance by the
more detailed descriptions in United States Patents 3,345,234,
3,748,151 and 3,887,678.
SUMM~RY OF THE INVENTION
The present invention seeks to provide a process for
making substrate for decorative, flexible sheet-type covering
material. The process of the invention comprises:
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a) coating at least one side of a flexible porous mat
with a layer between about 10 and about 150 mils thick of heat
curable mechanically frothed, flexible, foamed thermoplastic vinyl
polymer; and
b) then heating the layer of foamed polymer to a
temperature between the fusion temperature and the decomposition
temperature of the polymer to thereby cause the foam to thermally
collapse into a continuous fused film wherein;
i) said mat has openings which average between
about 1 and about 20 mils in the smallest linear dimension with at
least about 50% of such openings having smallest linear dimensions
between about 2 and about 10 mils; and
ii) the foam as applied to the mat has a viscosity
between about 3000 and about 25,000 cp.
Product of the invention is decorative, flexible,
sheet-type covering material comprising of a flexible, porous
mat having adhered to at least one face thereof a layer between
about 2 and about 50 mils thick of thermally collapsed and fused
mechanically frothed, flexible, foamed thermoplastic vinyl polymer
wherein:
a) the crushed layer has a continuous, non-porous
surface conforming to the general contour of the porous mat; and
b) the openings in the porous mat average between about
1 and about 20 mils in the smallest linear dimension with at least
about 50% of such openings having smallest linear dimensions
between about 2 and about 10 mils.
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DETAILED DESCRIPTION OF THE INVENTION
-
While the invention is applicable to porous
mats made from any flexible material, the preferred
material is glass fibers in woven or non-woven form
with non-woven glass fiber mats being especially
preferred.
The mats to which the invention is appli-
cable are those which are sufficiently porous so that
ordinary plastisol or organosol sealing materials
penetrate the openings of the matt, thereby making it
difficult or impossible to obtain a smooth coating of
plastic on the mat. Mats suitable for use in the
present invention are those in which the openings in
the mat average between about 1 and about 20 mils in
the smallest linear dimension with at least about 50%
of such openings having smallest linear dimensions
between about 2 and about 10 mils. Preferred mats
include those having a thickness between about 10 and
about 40 mils and a density between about 0.5 and
about 4 lbs. per 100 square feet. Such mats may be
manufactured by conventional techniques used for
manufacturing non-woven glass mats with the glass
fibers used preferably having an average diameter
between about 5 and about 20 microns, more preferably
between about 7 and 15 microns, and fiber lengths
between about 0.2 and about 1.5 inch. Binders con-
ventionally used for coating glass fibers may be
used and where used are normally present in amounts
between about 1 and about 50 wt% of the mat. Suitable
binders for coating glass fibers of the mats used in
the invention include, for instance, ureaformalde-
hyde, latexes, thermosetting resins such as poly-
ester resins, epoxy resins and the like and may
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include, among other conventional binders, those mentioned in
United States Patent 3,554,851 to Modigliani. The binder may, of
course, be applied to the glass fibers in the conventional manner.
As mentioned, the foam used in forming product of the
invention by the process of the invention comprises thermoplastic
vinyl polymer with vinyl chloride polymers and copolymers being
especially preferred. Vinyl polymers suitable for use in the
invention include a wide variety of vinyl materials such as those
described in the above-mentioned United States Patent 3,511,788 as
well as those conventional polyvinyl chloride (PVC) materials known
in the art for use in chemically foamed materials, including for
instance those described in the above-mentioned United States
Patents 3,458,337 and 3,293,094. Similar vinyl polymers in latex
form are also suitable. Mechanically foamed PVC plastisols and
organosols are the preferred materials for the thermally collapsed
layer of the product of the invention.
The mechanically frothed and thermally collapsed foam
layer of the product of the invention provides smoother surfaces
on porous substrates than the previously used chemically foamed
plastics and less porous surfaces than mechanically foamed
plastics applied and cured without collapsing. Thermally
collapsed foam layers of the invention are also more suitable for
this purpose than the relatively low density crushed foams which
are conventionally used as backing for draperies and upholstery
fabrics in the textile industry.
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As mentioned the present invention relates
to flexible sheet-type covering material suitable for
covering walls and floors. In order to achieve the
necessary flexibility in the finished product it is
necessary that the substrate as well as the collapsed
foam layer and other optional layers of the invention
be flexible rather than rigid. Plastic materials are
considered sufficiently flexible for this purpose
when, in the form of a foamed and cured unreinforced
1/4" foam sheet, they can be bent 180- around a 1"
mandrell without permanent set. Such materials are
generally known to those skilled in the flooring and
textile industries as are the various types of sub-
strates and other materials which are suitable for use
in making flexible decorative wall or floor covering
materials.
While flexible porous mats of the invention
having a layer of mechanically frothed and thermally
collapsed heat cured flexible plastic foam thereon may
for some purposes be suitable as substrates for sheet-
type covering material without further treatment, itis in many cases desirable to apply to the crushed foam
layer a conventional sealing coat of suitable material
such as PVC plastisol or organosol. In accordance with
a particularly preferred embodiment of the invention,
the layer of mechanically frothed and thermally col-
lapsed flexible plastic foam is further covered with a
conventional layer of foamed plastic such as foamed PVC
plastisol or organosol. This provides desired resili-
ency to the finished product. It will be understood
that additional foamed or unfoamed layers of conven-
tional materials for use in flooring, e.g. PVC plasti-
sols or organosols as well as layers of printing or
other decorative effects may be also used all in a
conventional manner. Conventional vinyl wear layers
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for optional use on products on the invention may, for
instance, comprise any of the PVC resin materials
normally used in connection ~Jith the manufacture of
sheet vinyl flooring and may specifically include but
are not limited to those described in the above-
mentioned U.S. Patent 3,458,337. Where used, such
- vinyl wear layers are typically on the order of between
5 and 25 mils thick for flooring materials and may be
opaque, translucent or transparent as desired. Other
layers of sealer, pigmented layers, plastisols, wear
layers, etc., known in the art may also be used.
PVC plastisol or organosol used in forming the
- optional foamed layer of the product of the invention
described above may be any of the conventional PVC
materials known in the art for use as foamed layers on
flooring materials and include for instance those
described in the above-mentioned patents 3,458,337 and
3,293,094. The foaming or blowing agent incorporated
¦ in the optional foamable plastisol may also be a
conventional blowing agent or catalyst-activated
blowing agent such as are well known in the art for
producing foamed plastisols or organosols. Suitable
blowing agents include, for instance, azodicarbonamide
(ABFA) and other conventional blowing agents such as
those enumerated in the above-mentioned U.S. Patent
3,293,094.
While a wide variety of thermoplastic vinyl
foam materials are suitable for use in the mechanically
frothed and thermally collapsed heat cured foamed
thermoplastic layer of the invention, selection of a
particular plastic for a given application preferably
takes into account such factors as the nature of the
porous mat to be coated, the desired viscosity of the
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foam material as applied to the mat, the viscosity of
the foamed plastic as applied, the particle size of PVC
resin, degree of solvation of the plastisol, etc.
While the viscosity of foamed thermoplastics
utilized in making products of the invention by the
process of the invention may vary widely depending upon
the type of mat and coating and collapsing conditions
used, preferrred viscosity of the foam as applied to
the mat is between about 3,000 and about 25,000
centipoises (cp) as measured ona Brookfield RVF
viscosimeter with a TA T-bar spindle at 4 RPM.
While coating of the flexible porous mat with
mechanically foamed plastic in accordance with the
invention is frequently carried out at room
temperature, this is by no means critical and coating
temperatures between about 50 and 150F. are suitable
with many of the commonly used plastics.
':
Coating of the mechanically frothed foamed
plastic onto the porous substrate in accordance with
the invention may be accomplished by any suitable means
such as, knife coating or extrusion. After the porous
mat is coated with mechanically foamed plastic in
accordance with the invention, the foamed plastic is
heated to thermally collapse the foam into a continuous
fused (cured) film. This is accomplished by subjecting
the foamed plastic to a temperature between the fusion
temperature and the decomposition temperature of the
particular plastic involved. For best results the
temperature used for thus thermally collapsing the
plastic foam will be in the range of from about 20F
above the fusion temperature of the plastic to about
20F below the decomposition temperature of the
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~i plastic. Suitable temperatures for thermally
¦ collapsing foam in accordance with the invention will
of course vary widely depending upon the melt
temperature and decomposition temperature of the
particular plastic used, but for the preferred
polyvinyl chloride plastisols and organosols will
frequently range between about 375 and about 425F.
Likewise, exposure times may vary considerably but will
frequently range between about 1 and about 5 minutes to
~ 10 achieve complete collapsing and fusing of the foamed
-: material.
The primary objective of the process of the
invention is to produce a product wherein the porous
mat is sealed with a plastic coating which would be
difficult to apply by other means. The process of the
, invention is especially useful in sealing porous mats
¦ with plastisols and organosols which in the unfoamed
~ condition would normally penetrate the mat excessively
-¦ due to their relatively low viscosity. By applying
such materials in the form of mechanically frothed
; foams, the significantly higher viscosity of the foamed
- 1 material is utilized to prevent excessive penetration
- of the coating material-into the mat. It will be
appreciated that while the coating of the present
invention does not penetrate the porous web or mat
excessively, some limited penetration is normal and
desirable so that the continuous plastic film resulting
from the process of the invention is partially embedded
in the fiber matrix. As the foam collapses due to
heating as required by the process of the invention,
the resulting continuous, nonporous plastic film
assumes the general contour of the surface of the open
fiber web being coated. Relatively smoother surfaces
may be obtained by coating the web with relatively
thicker layers of plastic. In applications where a
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smooth, level substrate surface is required, it is
therefore frequently desirable to apply to the surface
formed by the process of the invention a conventional
base coat, prime coat or smooth coat. Any conventional
smooth coat such as that described in U.S. Patent
3,519,469 can be used for this purpose.
-
The following example is intended to illustratea preferred embodiment of the invention without
limiting the scope of the invention.
,
10Example
A simulated floor covering material of the
invention was prepared by applying approximately 20
mils of mechanically frothed PVC organosol foam to one
, face of a non-woven fiberglass mat approximately 18
, 15mils thick and weighing 1.1 lb/100 ft2. The foam as
coated onto the mat had a density of 0.7 g/cc and a
viscosity of 9000 cp. The composition of the
organosol was as follows:
Parts by Weight .
PVC-polyvinyl acetate
copolymer resin 40
PVC homopolymer suspension
resin 60
Plasticizer . 75
Kerosine Diluent 7
Stabilizer 1.0
Limestone Filler 40
Silicone Surfactant 4
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After application of the foamed organosol to
the mat, the foam coated mat was heated for three
minutes in an oven operated at 370-F. in a first zone
and 350-F. in a second zone. The foam collapsed
completely in the oven and the organosol cured as a
continuous fused film partially embedded in the fiber
matrix. The thus sealed mat was then smooth coated as
described in U.S. Patent 3,549,469 by coating with
non-foamable PVC organosol, passing the coated sheet
through the compression nip between a back-up roll and
a steel drum operating at 320-F. and gelling the
organosol in a short wrap on the steel drum beyond the
nip.
After smooth coating, chemically foamable
PVC organosol was coated onto the gelled organosol
with a coating bar and gelled in an oven operated at
275-F. Non-foamable PVC organosol was then coated on-
to the gelled foamable organosol in the same amount
and the sheet was heated for two and a half minutes in
the 370-350-F. oven. The decorative printed layer
normally included in such constructions was omitted;
~owever, the sample sheet was identical to conven-
tional rotogravure cushion sheet vinyl floor covering
in all other respects. This sheet was free of blis-
ters, craters and pinholes and had the smooth, even
surface normally desired in a floor covering material.
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The glass mat used in this example was made
up of glass fibers having an average diameter of about
9 microns and an average length of about 0.75". The
fibers were coated with urea-formaldehyde binder with
the binder making up about 15 wt% of the mat. The
openings in the porous mat had smallest linear dimen-
sions averaging about 5 mils with almost all of
such openings having smallest linear dimensions be-
tween about 2 and about 10 mils.
While the invention has been described with
respect to certain embodiments thereof, it will be
apparent to those skilled in the art that various
changes and modifications may be made without depart-
ing from the spirit or scope of the invention.
