DE2623110A1 - METHOD OF HEATING A BUNCH OF FIBER - Google Patents

Description

BAUMGAR TNER PAPIERS S.A. , RENENS (Switzerland)

Method for heating a fiber bundle (addendum to patent application P 24 43 056. 6-23

The invention relates to an improvement and further development of a method for heating a bundle of dielectric fibers Material according to patent application P 24 43 056. 6-23 whereby the fiber bundle is guided through at least one resonance chamber and exposed to an electric or electromagnetic field.

In a preferred embodiment of this method, the fiber bundle, which was previously formed into a cylindrical strand has been shaped, which may have a round cross-section, subjected to heating in at least one resonance chamber,

0900. B419.12D. 13a / l3b

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through which the bundle is parallel to an electric field or the electrical component of an electromagnetic field is passed through. The bundle that was previously with A binder or a plasticizer can be soaked, is in itself a poor conductor of heat. Because the warming occurs through dielectric loss, consequently the temperature inside the strand is significantly higher than the temperature of the circumference because the heat developed in the middle of the bundle radiates very little to the outside. These poor heat radiation can cause local overheating cause which in turn can cause local melting of the fibers, for example if these fibers are made of cellulose acetate exist. This is because cores of compact mass are formed, which make the fiber bundle unusable, especially if this is intended to be used as a cigarette filter, because the filter effect is thereby canceled.

Purpose of the inventive improvement and further training is therefore avoiding this possibility.

This is achieved in a simple manner by the fact that when performing of the fiber bundle, a hot gas is blown into the resonance chamber through the resonance chamber.

The effect of this measure is of two types, namely both thermal and mechanical. The thermal effect consists in better radiation of the heat in the fiber bundle, as a result of which local overheating can be avoided with certainty. The mechanical effect consists in a more homogeneous arrangement

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of the fibers in the bundle through which the gas stream flows. The gas is blown in heated so that the heating due to dielectric loss not due to cooling of the fiber bundle is affected. Rather, the gas can be blown in at a relatively high temperature to accelerate the heating of the fiber bundle, whereby it can run faster through the resonance chamber, so that productivity the system is increased.

The hot gas, for example air or another inert gas or a mixture thereof, is used in FIG. 1 of the parent application device shown radially under pressure in each

IV
the resonance chambers 4 to 4 blown through openings which are provided for this purpose. In this case, the guide tube for the fiber bundle is either provided with perforations or is left out at all within the actual resonance chambers, with only pipe sections at the entry and exit of the resonance chambers being able to be retained.

So that the passage of the hot gas through the fiber bundle is disturbed as little as possible by the conveyor belt one expediently a woven tape, for which one can use the same, per se known materials.

It is also possible to increase the effect of the method even further by making better use of the electrical field to enhance. For this purpose, a gas is used whose dielectric constant is higher than that of the fiber bundle. To the In this way, the heat of the gas still comes from the gas

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which is released by dielectric losses in the gas,

Ia the case where the fiber bundle consists of fibers made of cellulose acetate, and has previously been impregnated with a heat-activatable binder, for example with triacetin for producing a cigarette filter without a cover, the dielectric constant can be of the hot gas be selected so _s to be higher than the dielectric constant of the binder. In this case, the gas advantageously consists of the vapor of water or a solvent such as propanol,

Ethanol or preferably methanol,

The improved and further developed method according to the invention can of course also be used in other ways than just the manufacture of cigarette filters, such as the manufacture of porous wicks for felt-tip pens.

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Claims (5)

PATENT CLAIM HE 1,) method of heating a bundle of fibers from di- ' electrical material, the fiber bundle through at least a resonance chamber is guided and exposed to an electric or electromagnetic field, according to patent application P 24 43 056. 6-23, characterized in that a hot gas is blown into the resonance chamber. 2. The method according to claim 1, characterized in that a hot gas with a higher dielectric constant than the fiber bundle is blown in. 3. The method according to claim 2 for heating a fiber bundle, which is previously activated with a heat-activatable binder was impregnated, characterized in that a hot gas with a higher dielectric constant than the binder is blown in. 4. The method according to claim 2 or 3, characterized in that the hot gas is steam of water, propanol, ethanol or Methanol is blown in, 5. The method according to any one of the preceding claims, characterized in that a bundle of fibers made of cellulose acetate is used. 609851/0733