Method and apparatus for the thermal treatment of impregnated material webs

A material web impregnated with a settable synthetic resin travels in vertical direction, from the bottom towards the top, through a first heat treatment zone where the solvent of the synthetic resin or plastic is evaporated and there occurs a chemical reaction. The tacky material web departing from the first heat or thermal treatment zone then passes through a cooling zone where it is cooled by means of a cooling medium to such a degree that it does not stick to the deflection or diverting rolls over which the material web subsequently is guided. After deflection of the material web the latter is moved in vertical direction downwardly through a second heat treatment zone where the chemical reaction proceeds. Prior to winding-up of the material web the latter is further cooled. Before the first deflection roll and between the first pair of deflection rolls and the second pair of deflection rolls there is arranged a respective blowing or blast nozzle which blows a cooling medium against the face of the material web which comes into contact with the deflecting rolls. Consequently, there is caused further cooling of the material web and there is still further reduced the danger of the web sticking at the deflection rolls. By incorporating a cooling zone between the first heat treatment zone and the deflection rolls the material web can be moved at greater velocities through the installation, without the danger that it sticks to the deflection rolls.

BACKGROUND OF THE INVENTION 
The present invention relates to a new and improved method of, and 
apparatus for, the thermal treatment of impregnated material webs, 
preferably those impregnated with a settable synthetic resin or plastic 
material. 
Generally speaking, the method of the invention is of the type wherein the 
impregnated material web is guided in an upward direction through a first 
heat or thermal treatment zone, then through a deflection or diverting 
roll arrangement, and thereafter is guided in a downward direction through 
a second heat treatment zone. 
This type drying method and apparatus for performing the same is 
particularly suitable for the thermal treatment of fleeces and fabrics 
formed of organic or inorganic fibres, especially glass fibre fabrics, 
wherein such web-like materials are impregnated with a thermosetting 
plastic material or resin. 
With heretofore known installations of this type employing vertical guiding 
of the material web the latter is deflected during the thermal treatment 
processes, i.e. is deflected between the first and second heat or thermal 
treatment zones. In this way it is possible to maintain the structural 
height of the installation within acceptable limits. The material web 
which departs from the first heat treatment zone is however still tacky 
since the thermal treatment has not been completed. This is accompanied by 
the danger that the material web might stick upon the deflection rolls. If 
it were intended to treat the material web in the first heat treatment 
zone to such an extent that the web, upon leaving such first heat 
treatment zone, no longer would tend to stick to the deflection rolls, 
then it would be necessary to correspondingly increase in length such 
first heat treatment zone, and therefore, there would have to be tolerated 
an increase in the structural height of the plant or installation or it 
would have been necessary to move the material web at a correspondingly 
reduced velocity through the plant. In order to be able to prevent too 
intensified setting of the impregnation agent in this case, the second 
heat treatment zone cannot be fully made use of as concerns its 
temperature. 
To prevent sticking of the material web at the deflection or diverting 
rolls it also has already been proposed to provide an additional cooling 
device directly before the first deflection roll. This additional cooling 
device is arranged at the side or face of the material web which comes to 
bear upon the deflection rolls and blows a suitable cooling medium, for 
instance air, against this one side of the material web. When the system 
works at high velocities of movement of the material web it is not 
possible to effectively preclude, through the use of these measures, that 
the material web will not become stuck at the deflection rolls. 
SUMMARY OF THE INVENTION 
Therefore, with the foregoing in mind it is a primary object of the present 
invention to provide a new and improved method of, and apparatus for, the 
thermal treatment of impregnated material webs, which is not afflicted 
with the aforementioned drawbacks and limitations of the prior art 
proposals discussed herein. 
Another and more specific object of the present invention aims at providing 
a new and improved method of, and apparatus for, the thermal treatment of 
material webs wherein even when working with large speeds of movement of 
the material web there can be effectively prevented adhesive binding or 
sticking of the material web at the deflection rolls. 
Now in order to implement these and still further objects of the invention, 
which will become more readily apparent as the description proceeds, the 
method aspects for the thermal treatment of impregnated material webs, as 
contemplated by the invention, is manifested by the features that the 
material web, after departing from the first heat treatment zone and 
before passing the deflection roll arrangement, is guided through a 
cooling zone. 
As alluded to above, the invention is not only concerned with the 
aforementioned method aspects, but also deals with apparatus for the 
performance thereof. According to a preferred constructional design of the 
inventive apparatus a cooling zone is arranged following the first heat or 
thermal treatment zone and before the deflection roll arrangement. 
In the cooling zone the material web is cooled to such a degree that it can 
be guided over the deflection rolls without any tendency to stick thereto. 
Since it is not necessary to accommodate the course of the thermal 
treatment in the first thermal or heat treatment zone to the requirement 
that the material web not stick to the deflection rolls, it is therefore 
beneficially possible to subdivide the thermal treatment process at both 
of the thermal or heat treatment zones in a manner such that also full use 
can be made of the second thermal or heat treatment zone.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Describing now the drawing, the plant or installation illustrated by way of 
example in FIG. 1 will be seen to comprise a first heat or thermal 
treatment zone 1, where there has only been illustrated the upper portion 
and which extends from the bottom towards the top of the illustrated 
arrangement. Neighboring such first heat treatment zone 1 is a second heat 
treatment zone 2 which extends from the top towards the bottom and of 
which likewise there has only been illustrated the upper portion. Above 
both of the heat treatment zones 1 and 2 there is arranged a deflection 
region or zone 3. The construction of both heat treatment zones 1 and 2 
extensively corresponds to the construction of both heat treatment zones 
of known installations and therefore can be assumed to be well known in 
this technology. At the upper region of the first heat treatment zone 1 
there are arranged in superimposed relationship and so as to be situated 
oppositely of one another the blow chests or casings 4 which are provided 
with air infeed nozzles 5, through which effluxes a downwardly directed 
flow of a heated medium, typically for instance a current of heated air, 
as the same has been illustrated by the arrows. At the lower end of the 
first heat treatment zone 1, and which lower end of such zone has not been 
particularly shown in the drawing, there is provided a suction device for 
sucking-off the heating medium. 
The second heat treatment zone 2 possesses at its lower region, which also 
has not been shown in the drawing, also blowing chests or casings 
containing air infeed nozzles, like the structure 4, 5 previously 
discussed, and through which a current of a hot medium, for instance a 
current of warm air departs which is then upwardly directed. As clearly 
illustrated, at the upper end of the second heat treatment zone 2 there is 
provided an only schematically illustrated suction device 6 which is 
equipped with inlet openings 7 through which passes the hot air and is 
conducted away. 
In the deflection zone or region 3 there is arranged in conventional manner 
a deflection roll arrangement which is constituted by four deflection 
rolls 9, 10, 11 and 12. 
The material web 13, which is impregnated in the usual manner with any 
suitable impregnation agent, passes through the plant in upward direction, 
i.e. in the direction of the arrow A, and moves initially through the 
first heat or thermal treatment zone 1 where it is guided between the 
oppositely located blowing chests or casings 4. The material web 13 which 
passes over the deflection rolls 9, 10, 11 and 12 is deflected and then 
subsequently moves in a downward direction, i.e. in the direction of the 
arrow B and travels through the second heat treatment zone 2. Between the 
second heat treatment zone 2 and the station where the processed material 
web is wound-up this material web 13 is cooled in conventional manner. 
To the extent previously described this plant or installation corresponds 
to conventional plants of this type. 
Now in order to avoid, even when working with large throughput velocities 
of the material web 13 that such web 13 will stick to the deflection rolls 
9, 10, 11, 12, a cooling zone 14 is arranged between the first heat 
treatment zone 1 and the deflection region or zone 3. In this cooling zone 
14 there are provided blowing chests or casings 15 which are arranged 
above one another with respect to the direction of movement A of the 
material web 13 and opposite one another with respect to such material web 
13. As schematically illustrated, the blowing or blast casings 15 are 
equipped with outlet nozzles 16, through which effluxes a current of a 
cooling medium which is directed against the material web 13, for instance 
an air flow, and the same has been illustrated by the arrows. Moreover, a 
suction device 17 is arranged in the cooling zone 14, this suction device 
being merely schematically illustrated and withdrawing the cooling medium 
out of the cooling zone 14. 
In the deflection or diverting region or zone 3 there are arranged three 
blowing nozzles 18, 19 and 20 which apply to the material web 13, at the 
face or side thereof coming into contact with the deflecting rolls 9, 10, 
11, 12, a cooling medium, typically air. The blowing nozzle 18 is 
arranged, viewed with respect to the direction of movement or travel A of 
the material web 13, forwardly of the first deflection roll 9, whereas 
both of the remaining blowing or air infeed nozzles 19 and 20 are arranged 
between the first deflection roll pair 9, 10 and the second deflection 
roll pair 10, 11. By means of a flue 21 or equivalent removal device it is 
possible to withdraw the cooling medium out of the deflection region or 
zone 3. 
Having now had the benefit of the foregoing description of a preferred 
exemplary embodiment of the invention there will now be described the mode 
of operation of the heretofore discussed installation or plant and the 
same is as follows: after passing through a conventional impregnation 
device the impregnated material web 13 is moved upwardly in vertical 
direction through the first heat treatment zone 1. The material web 13 is 
then impinged at both faces by the hot fluid medium which flows in 
countercurrent. In this first heat treatment zone 1 there thus initially 
occurs a slow heating-up of the material web 13, as well as an evaporation 
of the solvent and a chemical reaction (pre-polymerization, 
pre-polyaddition, pre-polycondensation). The material web 13 which departs 
from the first heat treatment zone 1, and which is still in a tacky state, 
then moves between the blowing casings or chests 15 of the cooling zone 
14. Due to the action of the medium which impinges the material web 13 at 
both of its faces this material web 13 is therefore cooled to such an 
extent that it can pass the deflection rolls 9, 10, 11, 12 without 
sticking thereto. Now in order to avoid that cooling air from the cooling 
zone 14 can reach the lower situated first heat or thermal treatment zone 
1, the suction device 17 withdraws a greater quantity of cooling medium, 
due to the applied suction action, then the quantity of cooling medium 
which is infed into the cooling zone 14 by means of the blowing chests or 
casings 15. The pressure in the cooling zone 14 is therefore less than the 
pressure prevailing in the first heat treatment zone 1. 
The three blowing nozzles 18, 19 and 20 within the deflection or diverting 
region 3, as already explained, therefore impinge the material web 13 at 
both of its faces with cooling air, so that there is brought about a 
further cooling of the face of the material web 13 which passes over the 
deflection rolls 9, 10, 11 and 12, with the result that there is 
additionally reduced any danger of sticking of the material web 13 to such 
deflection rolls 9, 10, 11, 12. In this regard it must however be 
mentioned that for the effective preventation of any adhesive bonding or 
sticking of the material web 13 the use of such blowing nozzles, 18, 19 
and 20 is not absolutely necessary and that in certain cases the cooling 
action which prevails in the cooling zone 14 is adequate for itself in 
order to prevent the material web from sticking to the rolls. 
After deflection of the material web 13 in the deflection region or zone 3 
the material web 13 is guided, in the direction of the arrow B, through 
the second heat treatment zone 2 where there progresses the previously 
initiated chemical reaction which has started in the first heat treatment 
zone 1 (post-polymerization, post-polyaddition, post-polycondensation). 
Prior to winding-up the material web 13 the latter, as already mentioned, 
is cooled, in order to rapidly bring the frequently still slightly tacky 
impregnation agent to room temperature and to stop the chemical process, 
and thus to ensure the endurance or durability of the impregnated material 
web 13. 
The described installation is particularly suitable for the thermal 
treatment of fabrics and fleeces formed of organic and inorganic fibres. 
In particular, it is possible to prepare by means of this installation 
impregnated glass fibre fabrics. 
As the impregnation agent there can be beneficially used, in particular, 
settable plastics (thermosetting plastics), for instance melamine, 
phenolic, polyester, epoxy and silicone resins. 
The impregnated material webs which have been heat treated in the described 
installation are preferably further processed into laminates, as the same 
are used, by way of example and not limitation, in the electrical and 
electronic industries, for instance for printed circuits. 
While there are shown and described present preferred embodiments of the 
invention, it is to be distinctly understood that the invention is not 
limited thereto, but may be otherwise variously embodied and practiced 
within the scope of the following claims. Accordingly,