1~21565
mis invention relates to a process for the manufacture of fibrous
webs, preferably webs of cellulose fibres, wherein an endless air-per~eable form-
ing wire is passed below a number of fibre distributors, discharging fibres which
under the influence of one or more suction boxes provided at the opposite side of
the forming wire are sucked towards the forming wire so as ~o form a fibre layer
thereon.
When manufacturing fibrous discharging webs by a prior art process of
the above mentioned type, the fibre distributors are mounted at intervals along
the endless air-permeable forming wire and a suction box is provided at each
fibre distributor.
Copending Canadian application No. 315,945 filed November 7, 1978 dis-
closes a process, wherein an endless air-permeable forming wire is passed belaw
a fibre distributor consisting of a number of fibre distributor units which are
built together and under which there is provided a suction box which is co~mon
for these fibre distributor units and which serves to keep the fibrous layer con-
stantly sucked against the wire while its thickness gradually increases.
The invention is based on the discovery that by using a process of the
above mentioned type a fibrous product can be obtained having at least one sur-
faoe layer which mainly consists of relatively long fibres and a central layer
mainly consisting of relatively short fibres.
A fibrous product of such a composition is especially soft and has a
gcod feed. Therefore, it is suitable for the manufacture of relatively light
fibrous products, especially fibrous products having a weight of less than 100
g/m . Such products æe p æ ticulaxly suitable for use as tissue paper including
facial tissue, paper towels, toilet paper etc.
The process of the invention is characterized in that the air-permeable
endless wire has op~nings having an area ex oeeding 1 mm and that the fibre mate-
rial passing through the wire below a given fibre distributor is passed to one or
--1-- .~",0`~
l~Z1565
more subsequent fibre distributors viewed in the direction of movement of said
wire.
By using a wire having cpenings with an area of above 1 mm2 only
relatively long cellulosic fibres discharged from the first of the number of
fibre distributors are retained by the wire, whereas the relatively short fibres
will pass through the wire and down into the suction box.
The relatively long fibres of the fibrous material passing through the
forning wire under the first fibre distributor are deposited there-
-la-
'~ :
~2~5
on, whereas the shor-t fibres again will pass through the wire when
said fibres are recycled to the Following fibre distributor and then
are sucked towards the forming wire with the long fibres already
deposited thereon. As the fibre layer becomes thicker, it also becomes
5 more dense and even relatively short Fibres will gradually be deposited
thereon .
When preparing fibrous products in the form of webs by using
several fibre dis-tribu-tors each consisting of a number, for example 6,
fibre distributor units and by supplying fresh fibrous material to
10 each fibre distributor, a fibrous product in which both surface layers
predominantly consis-ts of relatively long -fibres can be obtained.
This is achieved by supplying fibre material consisting of rela-
tively short fibres from the preceding fibre distributor to the rear
portion of the last fibre distributor viewed in the direction of move-
15 ment of the forming wire. In that case the relatively short fibres passrelatively quickly through the bottom of the fibre distributor and are
deposited on the layer already formed on the forming wire. The
relatively long -fibres, however, will be distributed over the whole
fibre distributor including its front portion. Within the front portion
20 they will be subjected to strong influences frorn the stirring means
provided therein because the relatively short fibres already have been
discharged from the fibre dis-tributor. Under these circumstances the
likelihood that these fibres will be brought into such a position rela-
tively to the openings of the bottom of -the fibre distributor so that
25 they can pass through said bottom, is increased.
Consequently, a surface layer of relatively long fibres is formed
- on top of the fibre layer already formed.
It should be mentioned that the term "distributor" herein is to
be understood as comprising also one of the distributor units forming
30 part of a fibre distributor composed of several of such distributor
units. In that case the fibre ma-terial which has passed the forming
surface below such a fibre distribulor unit is -transported to one or
more of the following fibre distributor units which, For example, may
be provided within the same housing.
A further advantage of -the process described is -that the fibre
layer initially deposited on the -Forming surface acts as a filter for the
mixture of fibres and air subsequently supplied thereto and conse-
quently reduces the loss of fibre material. The result is that the
production economy is improved and that the contamination problems
lS65
are reduced to a minimum.
When manufacturing fibrous proclucts mainly consisting of cellu-
losic fibres which ordinarily have a length of 0,5-3 mm, the forming
wire used is preferably a wire having openings which in the cross
machine direction have dimensions of from 0,5 to 1,5 mm. These open-
ings are preferably elongated in the machine direction and the length
of the openings in this direction are for example up to 3 times the
width of the openings.
The forming wire preferably consists of a woven metal net in
10 which the warp and weft threads form a plain weave. It is preferable
to use a net in which the distance between the weft threads is great-
er than the distance between the warp threads so as to facilitate the
cleaning of said net.
A particularly sui-table metal net is a net in which the metal
15 threads form a plain weave and in which the weft threads are straight,
whereas the warp threads form bends at the crossing points. In such
a net the weft threads are surrounded by the warp threads and con-
sequently the risk that fibres accumulate a-t the crossing points is
less than in the commonly used me-tal nets.
As mentioned above the forming wire preferably is a metal net.
However, it can also be prepared from threads of a plas-tics material
and is not necessarily in the form of a woven product. Thus, the
wire may be formed of a perforated metal or plastics film.
In a preferred embodiment of the process o-f the invention seve-
25 ral, for example 3, fibre distributors are mounted along the forming
wire, said fibre distributors each consisting of several, for example
6, fibre distributor units, each comprising a row of stirrers, said row
extending transversely o-F the forming wire, the fibre material passing
through the forming wire below the first fibre distributor being
30 transported to both the second and the third fibre distributor seen in
the direc-tion of movement o-F said wire. In this manner a suitable air
balance in the system of fibre distributors is obtained.
The transport of fibre material from the suction box below the
first distributor to -the second and third fibre distributor is generated
35 partly by means of a fan mounted in a conduit connecting the suction
box below the first distributor with the second and third fibre distri-
butors and partly with an exhaustion device which is connected to the
suction boxes below the second and third fibre distributors.
As mentioned above the fibre material from the suction box below
1565
`1
-~he l; sl fibre c.,s~ rir)uto~ is pref rably hlLroducecl in the real portio
of the ~hird fibre distribu~ol which is also fed with fresh fibre mate-
rial so as to obtain a top layer mainly consisting of long fibres.
~hen manufacturing relatively thin Fibrous webs by a process of
-the type defined in the introductory part of the specification, one or
more auxillary wires are ordinarily used for transporting the fibrous
web removed from the forming wire to a drying s-tation.
By using the above mentioned relatively open -forming wire, it
has been found that it is possible to introduce the thin Fibrous web
formed on the forming wire direcl ly onto a drying cylinder. This dis-
covery has significantly contributed to making an apparatus -For the
manufacture of fibrous webs more compact and to reducing the build-
ing, initial and operational costs for such an apparatus.
When the forming wire during the transfer oF the Fibrous web
on-to the drying cylinder is pressed against said cylinder, e.g. by
means of one or more pressure rollers, a surface pa~tern correspona-
ing to the surface pattern of the wire is formed on both sides of the
fibrous web. Consequently, the fibrous web is in contact witl~ the
drying cylinder essentially only in a pattern of points or lines and
corresponding -to the surface pattern of the forming wire.
This is of great importance as far as the subsequent removal of
the dried fibrous web from the drying cylinder is concerned. Thus,
previously a thin fibrous web ~,vhich adhering to a drying cylinder
over the full contact area can be removed there-From only in connec-
tion with the creping of said fibrous materiai. However, by utilizing
the process of the invention, the -Fibrous web can be removed from
the drying cylinder without simultaneously creping said fibrous web.
The fibres of the final fibrous web are bonded together by a
binder. Such a binder may be supplied to the fibrous ma-terial in
different ways. Thus, a solid binder, For example modiFied s-tarch
which is activated by supplying moisture thereto, can be introduced
into the deFibrator, For example a hammer mill, which is ordinarily
used for preparing the defibra-ted ma-terial supplied to the fibre
distributor .
When the binder is supplied to the Fibre distribu-tors together
with -the defibrated material, a significant portion thereof will pass
through the forming surface below the first fibre distributor and is
therefore primarily deposited in the fibre layer provided on top of the
first layer.
56~
In order to activate the binder, moisture, -For example water, is
sprayed onto the fibre web while it is present on the forming wire.
Excessive amounts of water are removed during the contact between
the fibrous web and the drying cylinder. During -the heating of the
5fibrous web the binder may be cured.
A binder in the form of a binder solution or suspension may also
be sprayed onto the fibrous web while it is present on the forming
wi re .
By using a thermocuring binder it may be necessary to heat the
10fibrous web to a higher temperature than the tempera-ture obtained
during the contact between the fibrous web and the drying cylinder.
This can be achieved by passing -the fibrous web through a
curing oven in which hot air is passed through the fibrous web after
it has been removed from the drying cylinder.
15During such heat treatment with the object of curing the thermo-
curing binder it is desirable to keep the fibrous web supported.
I n a preferred embodiment of -the process of -the invention such
support is provided by using the return run of the forming wire as a
support for the fibrous web during the curing process.
20Binder may also be supplied by applying to the surface of the
forming wire, e.g. by rollers, a binder solution or suspension having
a relatively high viscosity. The binder will primarily be deposited on
the protruding zones of the wire (the crossing points in a woven
metal net~ and will consequently be pressed into the fibrous web
25during the embossing which is effected when the -forming wire with
the fibrous web located thereon is pressed against the drying cylin-
der .
In this embodiment of the process oF the invention the binder
will predominantly be located in the embossed points or lines and the
30intervening zones are not compressed correspondingly. Therefore, a
product having a soft and absorbing surface and being voluminous is
obtai ned .
The removal o-F -the fibrous web from the drying cylinder is pre-
ferably effected with a doctor's knife. Depending on the shape and
35the mounting of such a knife, the fibrous web is removed in a creped
or non-creped state. When the fibrous web is creped, the length
thereof will ordinarily be reduced with about 20g6. In view of the
manner in which the fibrous web is in contact with the surface of the
drying cylinder, the fibrous web can be removed from said surface
- '., , ~,
~L~2~565
without creping said web. Thus, a fibrous web having a smooth
surface and essentially the same surface properties in all directions is
obtai ned .
The invention also relates to an apparatus for the manufacture of
5 fibrous webs made from cellulosic fibres, said apparatus comprising an
endless air-permeable forming wire, a number of fibre distributors
mounted along said forming wire, one or more suction boxes co-operat-
ing with each fibre distributor and mounted on the opposite side of
said forming wire.
The apparatus according to the invention is characterized in that
the forming wire has openings with an area exceeding 1 mm2 and that
it comprises conduits connecting the suction box or suction boxes
below a given fibre distributor with one or more subsequent fibre
distributors viewed in the direction of movement of the -forming wire.
The distributors of the apparatus according to the invention are
preferab!y of the type which comprises one or more rows of stirrers
rotating in one or more planes which are essentially parallel to the
surface of the -forming wire.
It is par-ticularly advantageous to use distributors of the t pe
2t~ disclosed in the specification of ~ patent applica-tion No. ~.6f~.
The individual fibre distributor uni1:s of such a fibre distributor are
preferably provided within the same housing and the stirring zones
are separated by separating walls of a type which allows fibre material
from passing from one stirring zone to the adjacent one.
In an apparatus comprising three of these fibre distributors,
each composed o-F for example 6 fibre distributor units, the suction
box or suction boxes below the first fibre distributor is (are) pre-
ferably connected with inlets of the second fibre distributor, said
inlets opening in the middle portion of the fibre distributor housing
and with inle-ts of the third fibre distributor opening in the rear
portion of -the fibre distributor housing.
The suction box or suction boxes below the fibre distributors
preferably comprise rollers suppor-ting the forming wire which is pas-
sed above said suction box or suction boxes. Such supporting rollers
are preferably mounted directly below the shafts of said stirring-
means because it has been -Found that an optimum air distribution
within the suction box or suction boxes is obtained with such a
moun ting .
A spray cabin having means for spraying water or binder solu-
7 ~2~5~;5
tion onto the fibrous web may be provided adjacent to the last fibre
distributor in the row of such fibre distributors.
The transfer of the -Fibrous web onto the drying cylinder is
preferably effected by pressing the fibrous web against said cylinder
while it is still in contact with the forming wire.
Thus, the apparatus may comprise one or more rollers which
both serve as supporting rollers for the -Forming wire and as pressure
rollers pressing the forming wire and the fibrous web located thereon
against the drying cylinder.
The pressure required may be generated by using a forming
wire which encircles a substantiai portion, for example up to 180, of
the periphery of the drying cylinder.
This embodiment is particularly preferable in case the return run
of the forming wire extends above the row of fibre distributors and
when it is desired to have that portion of the forming wire on which
the fibrous web is to be formed at the floor level.
The drying cylinder used is preferably an internally heated
drum. The surface of the drying cylinder is preferably heated to a
temperature of 100-200C and in particular 120-160C.
The apparatus also comprises means for removing the fibrous
web from the drying cylinder. It is preferable to use a doctor's knife
having an edge which is pressed against the surface of the drying
cylinder. As mentioned above, the means for removing the fibrous
web from the drying cylinder may be constructed in a manner so as
to simultaneously crepe the fibrous web. As is also mentioned above,
the invention permits the removal of the fibrous web without effecting
a creping.
The apparatus may also comprise one or more devices for winding
up the fibrous web so as to form a roll. If the binder used is a
thermocuring binder, the apparatus also comprises means for further
heating the fibrous web before it is cooled and wound up.
The means for further heating the fibrous web preferably compri-
se a suction box mounted on one side of an endless support belt and
heatincl elements with air supply means mounted a-t the opposite side
of said support belt.
When the fibrous web is to be subjected to such a further heat-
ing, it is introduced on said support belt and it is sucked onto said
belt under the influence of the vacuum in -the suction box. When the
fibrous web is advanced together with the support belt, it is heated
8 3L~ 6S
by hot air which is generated by the heating elements and which
under the influence on the vacuum in the suction box passes through
the fibrous web.
In a particularly simple embodiment of the apparatus o-f the in-
5vention, said support bel-t is a portion of the return run of the
formi ng wi re .
The invention wiil now be described in further detail with re-
ference to the drawings in which
Fig. 1 shows a portion of a preferred metal net for use in
10the process of the invention,
Fig. 2 shows the net illustrated in Fig. 1 in perspective,
Fig. 3 shows a preferred embodiment of the apparatus accord-
ing to the invention, and
Fig. 4 shows another embodiment of the apparatus according
15to the invention.
The metal net illustrated in Figs. 1 and 2 consists of warp
threads 1 and weft threads 2, the distance between the weft threads
being greater than the distance between the warp threads. Therefore,
the openings 3 in the net are rectangularly shaped. The warp threads
201 and the weft threads 2 form a socalled plain weave. However, the
weft threads 2 are straight, whereas the warp threads 1 form bends
at the crossing points with the wef-t threads. The net illustrated
presen-ts the advantage that it is easy to remove fibres, fibre lumps,
binder etc. therefrom when a brush rotating about an axis parallel to
25the longitudinal direction of the weft threads sweep over -the net
because the weft threads are not adjacent to the surfaces of the net.
The apparatuses illustrated in Figs. 3 and 4 are in principle
identical as far as the forming sections and the binder supply sec-
tions are concerned and the same components in these sections of the
30apparatus therefore have the same reference numerals.
The forming section consists of three fibre distributors 10, 11
and 12 which are mounted successively over a forming wire 13 which
is advanced in a direction illustrated by an arrow 14. Each fibre
distributor consists of six fibre distributor units mounted in a common
35housing 15. Each fibre distributor unit comprises a number of stirrers
mounted in a row perpendicular to the direction of movement of the
forming wire 13. The stirrers 16 have impellers which are located a
short distance above the bottom of the housing, said bottom having
565
the form of a screen. Separa~ing walls 17 are provided between ad-
jacent rows of stirrers 16. These separating walls 17 do not extend
fully to the bottom of the housing 15 and consequently fibres may
move from a zone below one row of stirrers 16 to the adjacent zone
below another row of stirrers 16.
Below each fibre distributor 10, 11 and 12 there is provided a
suction box 18, 19 and 20, respectively, containing several rollers 21
supporting the forming wire 13. The fibre distributors 10, 11 and 12
are connected with supply pipes 22,23 and 24, respectively, for
freshly defibrated fibre material. The suction box 18 is connected
with the middle portion of -the fibre distributor 11 and the rear por-
tion of the fibre distributor 12 via a pipe 25 comprising an air pump
26. The supply pipes for freshly defibrated fibre material also open
into the rear portion of the fibre distributor 12.
The suction box 19 is connected with an exhaust pump 29 via a
connecting pipe 27 and the suction box 20 is connected with the ex-
haust pump 29 via a connecting pipe 28. The apparatus shown also
comprises a spraying cabin 30 mounted adjacent to the Fibre distribu-
tor 12 and above the forming wire 13.
In the apparatus illustrated in Fig. 3 the return run of the
forming wire 13 is located below the fibre distributors 10, 11 and 12
and the spraying cabin 30 and the forming wire is supported by rol-
lers 31-36 of which the roller 34 is a guide roller and the roller 35 is
a tension roller.
The apparatus illustrated in Fig. 3 further comprises a rotatable
drying cylinder 37, a doctor's knife 38 and rollers 39, 40, 41 and 42
for supporting a fibrous web 43 formed in the apparatus before it is
wound up so as to form a roll 44.
In the apparatus illustrated in Fig. 4 the forming wire 13 ex-
tends around a drying cylinder 45 and the return run is supported
by the rollers 46-50 of which the roller 47 is a guide roller.
The apparaLus illustrated in Fig. 4 also comprises a doctor's
knife 51 and rollers 52, 53 and 54 for a fibrous web 55 which, when
wound up, forms a r-oll 56.
A suction box containing some support rollers 58 for the forming
wire 13 is mounted above the forming wire 13 between the drying cy-
linder 45 and the roller 52. On the opposite side of the forming wire
13 there is mounted a drying oven 59 and conduits (not shown) for
alr.
~21565
l~)
~ ;~)ell supl~ ying t, esl-lly d~ Fibrated cellulosic Fibrous md-ter,al
optionciln,~ containing a minor arnollnt of synthetic Fibres, For example
thermoplastic plastic fibres, to ~he -Fibre distributors 10-12 and by
dischat-ging air with the exhaust p ump 29 and transporting air contain-
~' ing relativeiy short fibres frorn the suc-tion box 18 to -the fibre di-
stributors 11 and 12, a fibrous la~.,er is gradually Formed on the form-
ing wire 13 of the appara-tus illustrated in Figs. 3 and 4, the bottom
and top layers oF said fibrous layer predominan-tly consisting of rela-
tively long -Fibres.
When the Fibrous layer has attained a desired thickness in the
fibre distributor 12, it passes through the spraying cabin in which a
binder solution can be applied to the fibrous layer.
In the apparatus illustrated in Fig. 3 -the fibrous layer is con-
tacted with the drying cylinder 37 which e. g . is heated to a tempera-
ture of 160C and at the same time i-t is strongly compressed.
The fibrous layer is then removed from the Forming wire 13 and
during the rota-tion of the drying cylinder 37 it is contacted with the
doctor's knife 38. At this stage the binder is cured and a seifgsup-
porting fibrous web 43 is obtained. The web 43 is then wound up to
form a roll 44.
A brush (not shown) is mounted along the re-turn run oF the
forming wire 13 and between the rollers 32 and 36 in order to remove
remaining fibres or binder From the forming wire 13.
The fibrous layer prepared by the apparatus illustrated in Fig.
4 is contacted with -the drying cylinder 45 while it is compressed be-
tween said cylinder and the forming wire 13. During this contact a
su-Fficient curing is initiated even when using a thermocuring binder
to provide a fibrous web which, when it has been removed from the
drying cylinder by means of the doc-tor's knife 51, is self-supporting.
After being removed from the drying cylinder the fibrous web 55
is brought into contact with the forming wire 13 under -the influence
of the vacuum within -the suc-tion box 57.
During i-ts passage above the suction box 57 hot air generated in
the drying oven 59 passes through the -fibrous web so as to complete-
Iy cure the binder. The fibrous web 55 thus formed can subsequentlybe wound up in the form of a roli 56.
The return run of the forming wire 13 is cleaned in the same
manner as discussed in connection wi-th Fig. 3.
I he invention will now be illustrated further with reference to
~Z1565
the fo owing e~<alnples:
~ MPLE 1
Cellulose pulp ~,type "Korsrlass Marma") and oxidized starch
5' ~ (type "Viscosol 220"~ in a proportion of 95% cellulose pulp and 5%
oxidized starch were introduced into a hammer mill. AFter forming a
fibrous web in an apparatus as illustrated in Fig. 3 and compl ising a
metal net having mesh openings ~ th an area of 1,5 mr~2, water con-
taining 1?~ dissolved oxidized starch (type "Viscosol 220") was sprayed
lO onto ~he fibrous web. Measurements showed that when fresh deFibrat-
ed material is supplied to the three fibre distributors in equal a-
mounts, about 20% of the -total amount of starting material passed
-through the metal net below the l~irst fibre distributor and are trans-
ferred to the second and third t ibre distribu-tor. Af-ter transferring
15 the fibrous layer from the metal net to the drying cylinder haviny a
temperature of 120C, a product was obtained which, before it was
removed from the drying cylinder with a creping knife, contained
about 25% water. The product, the length of which had been reduced
by about 25%, was wound up to form a roll. The fibrous product
20 obtained weighed 30 g/m2 and was suitable for -the manufacture of
toilet paper and tissue paper.
EXAMP L E 2
A fibrous product was prepared from the same starting materials
and by using the same technique as described in Example 1 with the
exception that the temperature of the drying cylinder was 150 C and
that the final product was wound up wi-thou-t any reduction of its
leng-th. Due -to the use of -the increased temperature of the surface of
the cylinder, the fibrous layer could be removed from -the ~rying cy-
linder wi-thout creping the product. ThereFore, the fibrous product
ob-tained could be wound up with a speed corresponding to -the rate at
which it was -formed on -the forming wire.
EXAMP L E 3
A fibrous product was prepared in the same manner as described
in Example 1, except -that -the arnount of cellulose pulp was 93% and
that also 2% thermocuring melamin binder ~of the type "Cymell 411")
were used. The product ob~ained weighed 25 g/m2. In order to obtain
56S
i2
a su~ iently nl~Jh wet strel-,clth the fibrous procuc-L rerrloved from
the h~ r)g cyllnder- was heated to a temperaLure of 160 C ror 1-2
secon~ s ~
EXAMPLES_4-6
Fibrous product:s having difterent weigh-ts were prepared by the
methods described in Examples 1-3. Thus, a fibrous product having a
weight cf 75 g/m2 (Example 4) was prepared by the method according
to Example 1, a fibrous prociuct havincJ a weight of 75 g/m2 ( Example
5) was prepared by the method according to Exai-nple 2 and a fibrous
product having d weigh-t o-F 80 g~m2 ( Example 6) was prepared by the
method according to Exarnple 3. The products having weights of 75
g/m2 and 80 g/m2 were sui-table for the manu-Facture of kitchen rolls
and paper towels. The product con-taining the melamin binder had an
15 increased wet strength.
EXAMPLE 7
The method according to Example ~was repeated but by using a
20 melamin binder of the type "Cymell 430". Preliminary investigations o-f
the product obtained showed no significant differences compared -to
the product prepared according to Example 3.
EXAM P L E 8
A fibrous product was prepared as described in Example 1 bu-t
with the excep-tion that part of -the cellulose pulp was replaced by
thermoplastic polye-thylene in fibre form. The polyethylene fibres had
essentially the same leng-th as the cellulosic fibres of the pulp materi-
al. The material in-troduced onto the Forming wire had the Following
30 composition: 80% cellulosic -fibres, 15% polyethylene -Fibres and 5% oxid-
ized starch. After the -Formation of the fibrous layer, a solution oF
oxidized s-tarch in water was sprayed thereon.
The product formed was more yeliow than -the product ob-tained
according to Example 1 bu-t the quality o-f -the product was such that
35 it was suitable for use for -the manufac-ture oF toilet paper.
EXAMPLE 9
A product was prepared by -the method according to Example 1
6 ~ ~
~Z~L56S
i3
witll he excep~,oll that cl 15'-~, starcll solution was applie, -to L le
formir j ~vire b~y roller~ belore tl,e fibrous layer was formecl thereon.
The product obLained was stronger bu-t no-t as soft as the product
accorcing to Exar,lple 1.
_AMPLE 10
A fibrous product was prepared by the method described in
Example 9 with -the exception that the concentra-tion of the solution
contain ng oxidized s-tarch which was sprayed onto the fibrous layer
before the latter was contacted wi-th the drying cylinder, only was
2%. The product ob-tained was suitable for the manufacture o-F ki-tchen
rolls and the weight of the product was 60 g/m .
When products are prepared by the methods described in the
above examples 1-10, the thickness o-F the material depends on the
pressure under which the -Fibrous layer is pressed against the drying
cylinder with the metal net and on -the temperature of the cylinder.
As a rule, however, produc-ts having a weight Of 30 g/m2 generally
have a thickness of 0,3-0,4 mm, and products having a weight of 75
g/m2 have a thickness o-F about 0,8-0,9 mm.
All the products prepared according to the above examples
showed a clear embossed pattern corresponding to tha-t of the metal
net. The fibres were strongly bonded together within -the embossed
zones and the product obtained had a considerable strength and were
25 voluminous, thus making such products suitable for the manufacture
of toile-t paper and paper tissue.
