CA1071349A - Elastic foamed material and process of preparing it - Google Patents

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.

Description

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, .j . . :
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~L~7~3~9 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.

_, 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 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 ~ 4 Trr~ rk o~ , b .

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.a maxim~ o.t clbo~ 0 perce~t by weigh~
EXA-'IPLE 2 ~ ~ .. _ 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 . ' ':' 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 S
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.3~9 ~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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Claims (2)

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,