ELASTIC FOAMED MATERIAL AND PROCESS OF PREPARING IT

MOUSSE ELASTIQUE ET PROCEDE DE FABRICATION CONNEXE

English Abstract

ELASTIC FOAMED MATERIAL AND PROCESS OF PREPARING IT
Abstract of the Disclosure
Hollow, gas-filled microspheres of aluminum sili-
cate, which are a constituent part of fly-ash obtained in
certain coal-fired power plants, are used as filler in
the preparation of elastic soft foamed material which in-
cludes a basic material comprising natural caoutchouc latex
or artificial caoutchouc latex or mixtures thereof, plastic
dispersions, soft polyurethane adducts, PVC plastisols or
the like, and the requisite additions. The foamed material
is intended for use as a backing of carpets.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. An elastic soft foamed material which includes a
basic material consisting of artificial rubber latex or natural
caoutchouc latex or mixtures thereof, and requisite additions,
said foamed material containing up to 50% by weight of reinfor-
ced cells consisting of gas-filled hollow microspheres of alumi-
num silicate which are a constituent part of flyash obtained in
certain coal-fired power plants, and hollow non-reinforced cells
produced by expansion of the basic material, the microspheres
having an approximate size of about 20 to 300 microns, a wall
thickness of 3 to 5 microns and an approximate volume weight of
about 0.3 to 0.7 gms/cm3.
2. A process of preparing the elastic soft foamed ma-
terial claimed in claim 1, comprising mixing gas-filled hollow
microspheres of aluminum silicate, which are a constituent part
of flyash obtained in certain coal-fired power plants, with a
basic material consisting of artificial rubber latex or natural
caoutchouc latex or mixtures thereof, and the requisite addi-
tions, whisking or foaming the composition to the desired density,
and then subjecting the composition to a coagulating and vulca-
nisation finishing treatment,

Description

349
This inyention relates to an el~stic soft foamed materi.al
and a pxocess of preparillg it,
In conve.ntional preparation of elastic soft foamed
materials, crystalline calc;te or dolomite as filler is mixed
with the basic materi~I, which may be caoutchouc latices, plas-
tic dispersions, soft polyurethane adducts, PVC plastisols etc.,
and w.ith the requisite additions, whereupon ~he composition i.s
expanded, tha~c is~ whisked or ~oamed, until the desired densit~
has been obtained. By increasing the filler conten~ and the
expansion it is possible to reduce the cost of the product,
which will, however, impair the strength propérties of -the ~ .
. product:.Quality xequirements therefore put a limit to these
- measures.
Since a couple of years, small gas-filled hollow
spheres of aluminum silicate, so-called microspheres, are
available on the market, these microspheres being a constituènt
part of so-called fly-ash, which is obtained in coal-fired
power plants. The microspheres occur in sizes of a~out 20-300
microns havin~ a wall thickness of between 3 and 5 microns and ;.
a vol~ne weight of 0.3-0.7 g/cm3. The microspheres have been
used as weight lowering agents in curable plastic composltio~s,
concrete etc. .
The object of the present invention is t~ improve, with
the aid of said microspheres, the prior art tvpes of elastic
. . .
so~t foamed materials, whlch as basic materlal have natural
caoutchouc latex or artificial caoutchouc latex or mixtures
thereof, plastic dispexsions, soft polyurethane adducts,
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PVC plastisols etc. ~y admixture of microspheres with the
basic mat:erial and subsequent expansion Of the m~terlal, a foamed
material is obtained after a finishing treatmentt said material
having two types of gas-filled cells, viz. hollow ~as-filled
reinforced cells, and hollow gas-filled non-reinforced cells.
q'he gaseous contents of the non-reinforced cells significantly
contribute to the indentation characteristic of the material~
By reason of the high compressibility of the gas the yas or
air cells increase the resilience and softness of the foam,
these properties being desirable from many aspects. The rein-
forsed cells, on the other hand, form a non-r~siiient structure
with the surrounding plastic or elastomer composition and are
mainly determinative of the strength properties of the marerial. ;
Characteristic of the new material is that it is considerably
lighter than prior art ma~erials of a corresponding type and
possesses better strengtll properties, particularly a higher
delamination strength.
The invention will be more fully described hereinbelow
and with reference to the ~ollowing ~xamples which ~elate to the
preparation of a latex composition in the previously known
manner and according to the new process, as well as to the pre
Faration of~PVC plastisols for mechanical foaming in the pre-
viously known manner and acaording to the new Process.
EXAMPLE 1
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Preparation of a latex composition in the previously known
manner (recipe ~) and according to the new process (recipe B).
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EX~MPI.~ OF IJ~TEX CGMPOS: TION Reci~e A Recipe B
A~tificial caoutchouc late~
(67 percent dry s~lids content) 10~ 100
Vulcanizin~ paste
(40 percent dry solids content) 55 55
Natural caoutchouc latex
~60 percent dry solids content) 115 115
Crystalline filler 135 ---
Microspheres, ceramic --- 100
405 370
Poamed to y/liter - 38G 230
The composition is continuously ~ed to a Eur-O~atic~
type foaming machine, in which air is mechanically whisked into
the composition. Recipe B which contains spheres of a density
of about 0.6 g/cm , yields, after the same amount of air has
been whisked in as in recipe A, a foam which is about 150 g
lighter per liter.
The foam is supplied to a coating machine, in which the
foam is applied with the aid of a roll or doctor blade to a
web, for instance a textile carpet. The web with the foam is ~,
moved for vulcanisation through ovens having a temperature of
about 150 C.
When tested, -the foamed material thus prepared prQved to
have far better mechanical properties, for instance a higher
dQlamination strength.
- The quan~lty of microspheres added ma~ vary and amounts to
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.a maxim~ o.t clbo~ 0 perce~t by weigh~
EXA-'IPLE 2
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Prep~ration of ~!VC plasti s015 for mechanical foaming in
.he prevlously known manner (reci.pe A~ and according to the new .. .
proce$s (recipe B~. .
EXAMPLES O~ PVC PLASTISOLS FOR MECHAN CAL FO~r~ING
~ecipe A Recipe B
P~C 100 100
Plasticiz~r 60 60
S~abilizer . ~. 2
Foam emulsifier 4 4
Cr~stall.ine filler, for instance calcite 20
Micros~heres, ceramic ~-- 20
. ~.86 186
Foamed ~o ~ t;er 500 425
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The plastisol i5 continuously fed into a Eur-O~Matic
or Oakes type foaming machine. In this machine air can be
whisked into the PVC paste because of the existence of foam
e~uls.ifiers i.n the)composition. These emulsifiers can also be
soap or silicon type emulsif.iers.
Depending upon t:he formulation of the composition and
the amount of air added it is possible to obtain a lighter ..
or a heavier foam. ~ecipe A includes a normally crystalline
filler (density of about 2.6 ~/cm3~ while recipe B contains ~
microspheres~ ~ecause o~ the lower density of the microspheres
~about 0.6 g/cm3) recipe B, after whisking wit~ the same
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~mO~lIlt of ~,ir as in recipe A,yields a foam which is about
75 g~liter lighter than the calcite-cont~ining oam according
to recipe A.
The mechanical strength of a foam is dependent int~ al.
on the volume weight and the employed volume of fil~er. A1~
though the fill volume is higher for the foam containing
microspheres the delamina~ion strenqth of this f~am is twice
that of a foam having calcite as filler. The admixture of
microspheres thus gives a foam of superior mechanical ~ro-
perties.
The quantity of microspheres added may vary and in
the present instance may amount to a maximum of about 50
percent calculated on the total weight of the composition~ -
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