Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a process intended to
improve the physical properties of non-woven fabrics, parti-
cularly glass wool, for the purpose of rendering said
fabrics more receptive to print. The invention also extends
to products obtained by this process.
Non-woven fabrics are generally used as backings for
wall coverings, especially for floor coverings.
Less and less use is being made of asbestos for the
construction of floor covering backings and efforts have
therefore been made to replace asbestos by various other
substances, among which glass wool is increasing in impor-
tance.
A usual method is to impregnate a sheet of non-woven
fabric, usually of fibre glass, with a plastisol, with a
double impregnation process in wnich one application is
given to the reverse side in order to stop up the pores and
the other to the front in order to obtain a perfectly smooth
and non-porous surface, so that in a subsequent neliogra-
phic printing process the ink will not "spread" on the support.
20 This "double impregnation" is generally performed in two
successive steps.
After this "double impregnation", which in fact is a
front-and.-back coating operation, the product is gelled in
an oven through which the treated fabric is caused to cir-
culate, in most cases continuously.
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-- 2
This process nevertheless suffers from certain draw-
backs resulting from the fact that the coating of two surfaces
of a sheet of non-woven material which is nevertheless not
impregnated all through will frequently cause a certain
quantity of air to be trapped in it. Subsequent heat treat-
ments often cause the trapped air to expand under the effect
of the heat and to form irregularities on the surface which
render the product unsaleable.
The use of a gelling oven also considerably increases
the size of the production lines, the said furnace being compa-
ratively long and the output speed very limited.
The present invention thus intends to remedy the afore-
mentioned drawbacks of the existing processes.
According to the present invention thereisprovided
a process for the treatment of a web of non-woven fabric, wherein
a plastisol having a Newtonian viscosity between 4 and 30
poise is applied at a temperature between 5 and 50C to one
single surface of a web to impregnate the non-woven material,
whereafter the impregnated web is pressed by a pressure roller
against a cylinder heated to between 130 and 180C, the
impregnated side of the web of non-woven material being in
contact with the said cylinder and at least partially covering
said cylinder.
The said impregnated surface is the side on which the
eventual heliographic printing will be carried out.
Under the conditions stated three results are observed
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which, occuring in combination, were to-tally unexpected, i.e.
the plastisol is completely gelled without the impregnated
fabric sticking to the roll, so that a good surface finish
is obtained, the fabric is impregnated all through and the
reverse side is pre-gelled and dry when leaving the cylinder.
After the cooling the resulting product undergoes helio-
graphic printing and constitutes a semi-finished product
serving as a base, particularly for the production of floor
and other coverings.
The exact temperature for the treatment is chosen in
accordance with the speed at which the product passes over
the cylinder and with the diameter of the latter. A skilled
operator will have no difficulty in selecting it in accor-
dance with the installation available to him, which largely
lS governs the speed at which the fabric moves and the diameter
of the cylinder that can be used, as well as the appropriate
temperature, by a series of tests performed in order to deter-
mine how to set the equipment in such a way that the fabric
2~ will be impregnated all through but will not stick to the
roll. -~
When it passes over a cylinder of about 2 m in diameter
at a speed of about 8 to 40 m/min, in such a manner that the
material is in contact with approximately 75~ of the outer
perimeter of the roll, the best temperature will be of the
order of 150C.
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In tne usual present-day installations a temperature
below 130C prevents thorough irnpregnation, while if it is
above the level indicated the f:Luidity will prove excessive,
making it difficult to apply the plastisol satisfactorily
and resulting in surface finishes which are unsuitable for
a subsequent heliographic printing process.
The plastisol is of a type customarily employed for
coatings. Within the viscosity range stated, i.e. 4-30 poise,
preference is given to a viscosity of 6-15 poise, particular-
ly to about 8 poise. The viscosity range can easily be ob-
tained from commercial plastisol preparations, with the use
of conventional dilution agents or, where necessary, thicke-
ning agents.
The rheological behaviour of the plastisol adopted may be
substantially Newtonian, but slightly pseudo-plastic charac-
teristics are nevertheless acceptable. A dilatant plastisol is
however to be avoided.
When causing the material to pass over the heated cylin-
der, the non-impregnated surface is simultaneously pressed
- 20 with a presser roller, preferably lined with an elastic sub-
stance such as rubber.
It is noted that under thèse circumstances a "pad" of
plastisol,which has the effect of creating an even film of
this substance, forms upstream from the point of contact bet-
ween the material and the heated cylinder. This provides a
3 1~3S5~B
surface in the desired state, similar .to that obtained in
calendered films. A further unexpected effect, however, is
that this "pad" of plastisol remains free of any thickening,
which would make application impossible.
In practice the process can be carried out by the method
described below by reference to a schematic diagram of a
suitable installation for the purpose.
The one single drawing attached illustrates a suitable
installation for the impregnation of a composite backing con-
sisting of any kind of base to which a sheet of glass fibre is
applied.
~ The drawing shows a composite backing 1, consisting of a
; base and a sheet of glass~an~ conveyed to an applicator roll
3 rotating in a tank containing a plastisol. The surface
formed by the sheet of glass~is in contact with the applica-
tor roll and is supplied with a suitable quantity of the
plastisol.
After this application the film of plastisol applied is
smoothed on a return roll by means of an "air knife" 6 for
the emission of a thin film of air. The surplus plastisol is
collected by a plate 7 integral.with the tank 4 and returned
to this latter.
The composite backing impregnated in this manner then
passes to a heated cylinder 10 to which it is applied by cau-
sing it to pass between the said.roll and a rubber-covered
presser rol.ler 12. A conventi.onal.:device.is used for the pur-
~'13.55~B
pose of ensuring even application, at adjustable pressure,of the presser roll 12 to the roll 10.
The plastisol-coated surface of the backing is applied
to the cylinder 10 in such a way as to cover about 75-80% of
the perimeter of the latter, as already indicated, the roll
Deing heated, for example, to a temperature of the order of
150C
After passing over the roll the support can be detached
from the latter without difficulty and is taken up by a return
roll 15, from which it goes to a heliographic printing press,
not shown in the drawing.
Among the plastisol compositions whicn can be used, men-
tion may be made of the following:
PVC ' 100
: 15 Stabilizing agent 2
Mixture of plasticizer of the
phthalate type 60-120
Charge of crystalline dolomite30-200
2 0-15
(preferably 2)
~; b~ e,
~20 The sheet of glassAmay be a conventional product such as
a sheet of glass wool treated in such a way as to render it
compatible with the PVC such as described in French Patent
No 2.295.836, P.l, line 15.
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In particular, a sheet of glass~of the "Schuller" or
"Ahlstrom" type can be used, possibly pre-treated, on a com- `
pact or foamable PVC support.
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The invention wlll be described in greater detail by
reference to a preferred method of carrying it out, this ser-
ving solely as illustration and having no limitative effect.
A composite backing consisting of a base of 2~0 g/m2 of
PVC covered with 60 y/m2 of glass wool is given an applica-
tion, at the rate of 500 g/m2, of a plastisol of the follo-
wing composition:
PVC 100.
Stabilizer 2.
Mixture of plasticizer of the phthalate type 90.
Charge of crystalline dolomite 35.
Tio2 2.5.
The coating operation by the aid of the plastisol can becarried out in the type of installation described in con-
junction with the accompanying drawing, but use can also bemade of a coating roll, a coating device of the scraper type,
a reverse roll or an equivalent coating device enabling the
coating substance to be proportioned in the desired quantity.
The backing thus impregnated is conveyed onto a gelling
20 cylinder 10, such as that shown in the attached diagram, -
passing under a presser roller 12, regulating the pressure
to between 0 and 200 kg and preferably to 40 kg per linear
metre.
The roll is heated to 150C, and under these conditions
a support is obtained which can be used for the production
of wall coverings or decorative coverings but of which
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the main purpose is that of floor coverings. This support
contains no air occlusions, of whicn the drawbacks have been
mentioned farther back.
The good results obtained by the method of the invention
are believed to be due to the selection of a plastisol being
substantially Newtonian which undergoes a pressing by the
effect of tne pressure roller, thus forming a "pad" which
remains free of thickening, i.e. a pad which is continuous-
ly renewed under production, the fresh material being fed
being substantially equal to the material which is used in
the operation.
This renewal prevents the gelling of the pad of plastisol
by the heating effect of the cylinder.
It should be noted that a clearly pseudo-plastical pla-
stisol should be avoided as the product would not suitablyimpregnate the fibers while a dilatant plastisol would cause
a structuration (i.e. thickening) of the pad.
Although a description has been given of pratical exam-
ples and suitable installation for the performance of the
invention, numerous variants are open to the man of the art
and that the invention is not limited to the said examples or
to the eguipment illustrated.
ïn particular, for example, the treatment according to
the invention can be applied to a sheet of fibre glass alone
or to a composite product consisting of a sheet of fibre
glass on a base, whether foamabLe or not.
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Furthermore, the non-woven fabric may consist of a
material of a different nature from fibre glass.
