The object of the invention is a method and an apparatus for production of carburized fibres in the thermal bonding process of powdered carbon and thermoplastic fibres.

The method of carburized fibres production is known as joining of the active carbon by means of bonding agents, which mostly are binders like latex, rubber and synthetic resins. After fibres impregnation by a binder and removing of its excess, the powdered carbon is coated and all together is dried in a temperature appropriate for a given binder. This method causes reduction of potential carbon activity even up to 50% by sealing some of pores.

The method of coating of the powdered carbon on fibres produced directly from the polymer, in the moment of fibres production is also known. This method does not assure durability of the bonding between the active carbon and the fibres surface.

Disadvantage of this method is that one does not obtain loose fibres with active carbon, but only fibres formed in the nonwoven. The method of absorptive carbon nonwoven production and the apparatus for applying this method are known according to the patent application no P. 319065. This method is described below.

The active carbon comminuted to granulation below 0,71 mm is mechanical introduced into fibre mass formed from the cut chemical fibres. So filled fibre-carbon mass is put into the area of high temperature operation, and next in order to make a bonding between carbon and fibres durable it is cooled down by means of the cold airflow. This method also does not assure production of loose fibres with active carbon, but only fibres formed in the nonwoven.

The apparatus consists of five block areas. First supply area is equipped with shaft co-operating with rewinder and transporter with a stretcher unit facilitating travel of the nonwoven under the area with the container including active carbon. The area of carbon spreading connects with the area of radiator heating and next with the cooling area equipped with the cooling fan. The final area of the apparatus is layshaft co- operating with a winder and receiving shaft. The chutes for accumulation of not bonded carbon are placed under the container with active carbon and also under the radiator and the fan.

In order to obtain loose carburized fibres, the thermal bonding method of powdered active carbon and thermoplastic fibres has been worked out. The method relies on the fact that the fibres are mechanically guided in a form of the cable and at the beginning they are spread with active carbon and then in a stretch state they are exposed to high temperature operation, which plastifies the fibres and causes melting of carbon into their structure and then they are taken out of the operation area and preferably exposed to crimping process. The cable of fibres spread with active carbon taken out from the area of high temperature operation, before crimping process, is preferably additionally heated up and mechanically burnished.

The apparatus according to the invention has a chamber for active carbon spreading with a feeder and a heater that plastifies fibres. It also consists of a set of shafts which stretch and expand the cable of fibres, placed between the chamber for

active carbon spreading and the heater, behind which there is a head for fibres crimping with the set of squeezing-receiving shafts, The apparatus preferably has additional heater situated adjustable to the plastified cable of fibres, between the heater and the set of squeezing-receiving shafts.

The method and the apparatus according to the invention assure large uniformity of active carbon spreading and durable bonding with the fibre structure.

Carburized cable of fibres, after earlier cut on the appropriate sections, enables easy production of nonwoven or yarn and from them woven and knitted fabrics, which allow wide usage in the different branches of industry.

The object of the invention is shown as an exemplary, schematic model in figure.

The apparatus consists of the feeder 5 and the chamber 4 for active carbon spreading. The fibres in the form of a cable 1 are supplied to the chamber. The cable that is a strip of continuos, preferably unary fibres without determined twist, is taken from the container 2 by means of set of feeding shafts 3 with velocity which enables introducing non stretched strip with loose fibres. The cable introduced to the chamber with excess is waved and has cross-section of oval shape similar to ellipse. This facilities penetration of carbon particles, deep into a cable mass.

The radiator heater 7 is situated on the upper part, behind the chamber with feeder. The cable 1 is supplied to this heater in a stretch state by means of the set of stretch-expand shafts 6, which cause flattening and widening of the cable at least two times in comparison to its cross-section in the carburizing chamber. In the heater it is exposed to high temperature operation, which plastifies the fibres and causes melting of the active carbon into their structure.

Air temperature in the heater is adjusted in the range from 90 to 150°C, depending on softening point of fibres included in the cable. The cable is guided

through area of heat treatment with velocity ranges from 1 to 15 m/min by means of the set of squeezing-receiving shafts 9 with adjustable pressure ranges from 0,5 MPa to 3 MPa. This set coupled with drive motor 11 is situated close to the head 10 for fibres crimping, in which the apparatus is preferably equipped with. The velocity of the set of shafts is adjusted depending on line mass of the cable and masses of the singular fibres in the cable. It assures plasticization of the fibres in the heating area and proper initial bonding with carbon particles. Different kinds of continuos thermoplastic fibres are suitable for carburizing process. For example polipropylen fibres with line mass ranges from 5 to 20 dtex, formed initially in the cable with line mass ranges from 20 to 100 ktex.

The apparatus is additionally equipped with electric heater 8 situated preferably adjustable according to the cable of fibres 1, between the heater 7 and set of shafts 9.

This heater placed in appropriate distance, additionally plastifies fibres and enables bonding of the nonbonded in the heater carbon particles with the fibre structure. It is done together with the burnishing process of the fibres cable by the set of shafts 9.

Generally, this process increases durability of the carbon bonding with the fibre structure and the quantity of the bonded carbon. After crimping process in the head 10, the cable with carburized fibre is gathered in the container 12.

Continuos fibres in the form of the cable 1 are introduced without stretching, with excess into chamber 4, where with help of the feeder S a spreading of powdered active carbon takes place. It is done with possibility of the spreading quantity adjustment, according to the consumption needs. Loose fibres in the cable enable fairly uniform spreading of the carbon in the whole mass of the cable. When the cable leaves the chamber, it is flattened and stretched in the set of shafts 6 and then introduced into the heater 7 in the area of suitable high temperature operation, that plastifies fibres and causes fairly melting of the carbon particles into the structural surface of the fibres,

without negative influence on the fibres properties. It is obtained by using, for the given kind of fibre, appropriate parameters of temperature and heating time depending on the velocity of the cable motion.

Precipitated, during the cable course from the chamber 4 to the set of shafts 6 excess of the carbon particles is transferred by the chute, back to the chamber or into a separate container. The cable of fibres after leaving the heater is additionally heated up by the heater 8 and next burnished by means of the set of shafts 9 after which it is crimped in the head 10. Solidification of the fibres structure is performed in the ambient air. Crimping of the fibres executed in the head increases their grafting and improves their yarn properties.

After earlier cut of the fibres cable with coated and fixed carbon, on appropriate sections, one obtains wide area of its processing possibilities and production of nonwoven or yarn and from them woven and knitted fabric. The manufactured materials have wide range of applications in domains of filtration, air conditioning and ventilation. They can be used among others in motor, chemical or food industries and for production of individual protectors like respirators used in mining, metallurgy or military service.