DE19941106A1 - Vulcanizing process, for rubber or silicone, uses radiation with a wavelength in the IR range - Google Patents

Abstract

At least part of the energy for vulcanizing the material is provided by electromagnetic radiation from a radiation source(3), the radiation having a wavelength falling within the infra-red(IR) range. Independent claims are made for: a) process equipment for vulcanizing rubber or silicone including a radiation lamp(3) emitting radiation in the IR range; b) use of an IR source for vulcanizing rubber or silicone.

Description

The invention relates to the vulcanization of a material, especially rubber or silicone, the vulcanizing is effected or supported by heating the material.

In numerous different manufacturing processes today days a material shaped in a certain way, the Ma material is initially plastically deformable. By Vulkani The material is in an elastic state brings.

For example, such a material is made using the extru diertechnik continuously in a quasi-endless, long stretched profiled shape brought and so ge brought material vulcanized continuously. For this is the Known use of continuous furnaces in which the material is heated up to a temperature specified in a Temperature range, for example 200 to 220 ° C. The The specified temperature range must be observed. Becomes If the temperature range is exceeded, the material burns at least on its surface. Will the temperature range falls below, does not find sufficient vulcanization instead of. In both cases, the desired elasti are not properties of the material. The Vulkanisie  In a continuous furnace, it typically takes a few minutes or even longer.

For vulcanizing the material, both in continuous furnaces and also in other ways, e.g. B. if the material for a be time placed in an oven and then how which is removed, the material in the initial phase se of the vulcanization process in particular due to its Deform your own weight plastically. So it comes up rapid heating of the material, at least on its upper surface area. When using continuous furnaces or other furnaces prevents the temperature in the oven from increasing may be high, otherwise the permissible temperature rich is exceeded. The temperature difference between the Oven temperature and the temperature of the not yet heated Material at the beginning of the vulcanization process is so limits, which is why the heat transfer from the oven to the mate rial is limited.

The object of the present invention is plastic deformation prevent extruded material.

The task is accomplished by a process according to the characteristics of the Claim 1, by a device with the features of Claim 11 and by use with the features of Claim 15 solved. Further training is the subject of each because dependent claims.

At this point it should be expressly pointed out that with the term "vulcanizing" any form of networking, esp special of polymer chains, should be understood.

According to a central idea of the present invention, at least part of the necessary to heat the material energy, if possible directly after extrusion,  by electromagnetic radiation from a radiation source transferred to the material, at least essential, the Radiation components in the wel cause heating of the material length range of the near infrared.

Near infrared (NIR) is understood to mean that the waves length in the range between the visible wavelength range and is 2.0 µm. In a preferred embodiment of the inven is understood by NIR that the wavelength in the loading rich between the visible wavelength range and 1.4 µm, in particular up to 1.0 µm.

Compared to conventional ovens, the radiant heating has basically the advantage that they control much better is bar and can be effected much faster. In order to it is possible to close the material with high heating output heat without the environment of the mate to be vulcanized rials takes on a high temperature. Warming can also can be ended within a short time by irradiating the Material finished or with low radiation power is continued. Furthermore, on the Vulkanisie tion following cooling process is much faster Cooling can be effected if desired, because the Ambient temperature much lower than at the Verwen of ovens and therefore the vulcanized material due to thermal radiation and convection in can give off heat for a short time.

In a further development of the method, the electromagnetic table radiation emitted by a radiation source, the has an emission temperature of 2500 K or higher, in particular those of 2900 K or higher. Such radiation sources emit animals with such a high electromagnetic radiation Radiation flux density that a particularly rapid heating of the material is possible.  

The material is preferably selected or prepared in this way rides that its degree of absorption in the near infrared increases values has more than 0.4, in particular greater than 0.6. So that is ge ensures that a substantial proportion of the irradiated NTR radiation is absorbed by the material. Prefers will continue that the penetration depth of the NIR radiation in the material at least 1 mm, preferably at least 2 mm is. The depth of material is understood to be the depth of penetration the one at which the penetrating NIR radiation on 1 / e of the beam Lung flux density on the surface of the material decreased Has.

In the case of further training, the material is not absorbed based, reflected radiation components of the electromagnetic radiation reflected back in the direction of the material. This measure allows effective use of the ver added radiation to heat the material, d. H. high efficiency. The alternative is expediently or additionally beam emitted by the radiation source not in the direction of the material to be vulcanized is emitted, reflected in the direction of the material.

Preferably the surface temperature of the material by controlling the radiation flux density on the material incident radiation and / or by controlling the irradiation duration set to a predetermined temperature value. This means that by properly controlling the radiation flux density does not exceed the specified temperature value becomes. In the case of further training, the focus is on the material apt radiation flux density during heating of the Ma terials are not kept constant over time, but at the latest when the specified temperature value is reached or after decreased or reduced to zero. Under that on matter The incident radiation flux density is the radiation  understood flux density, based on the same local Be of the material. With continuous funding the material in one direction of movement can therefore be a sta stationary radiation flux density that does not change over time Distribution set along the material's path be so that the radiation flux density at one point of the funding path is constant over time, but in funding direction tung decreases. In addition, of course, the local one Radiation flux density distribution are changed over time, especially if an adjustment of the temperature value is required derlich, or the specified temperature value is not he is sufficient or exceeded.

The surface temperature is preferably at least in a part of the material measured and regulated. Under Such a sub-area is also used to promote material as a fixed area on the conveyor path in one direction of movement understood the material. In this case it will be the waiter surface temperature of the material in a local area measure, the material continuously through this loading is richly promoted.

In one embodiment of the method, the material is long stretched and is continuously by an irradiation richly promoted in which the electromagnetic radiation the material hits. In another, preferred configuration device becomes the surface temperature in the irradiation area rich and / or in the conveying direction behind the irradiation area richly measured without contact.

Furthermore, the material according to at least part of the Be radiation with a conveyor for conveying the material than, in particular with a carrier device for receiving the weight of the material to be contacted, whereby the material contacting the conveyor  already rich in material due to the radiation least partially vulcanized. The duration is here the irradiation of the material area coming into contact preferably not more than 3 seconds, especially not more than 1 second. This allows vulcanization or Partial vulcanization of the material at least on the surface of the material area coming into contact, preferably one Vulcanization or partial vulcanization of the material anywhere on its surface so that when the mate comes into contact rials with the conveyor or with a not be moved the carrier of the material no unwanted plastic Deformation of the material occurs.

For a device for vulcanizing a material, ins special rubber or silicone, it is suggested that the Device a radiation source for the emission of infrared has radiation, the radiation source being such it is drivable that radiation energy essential parts lie in the near infrared, and the radiation source being the is arranged that the material at least partially Vulcanizable due to absorption of infrared radiation is.

In particular, the device has an extrusion device to extrude the material in an elongated form on and is a conveyor for removal and / or for Wei arranged treatment of the extruded material such that the extruded material before the first contact can be irradiated with the conveyor. Here is the irradiable section of the conveyor path between the Ex trudiereinrichtung and the conveyor preferably not more than 8 cm, especially not more than 4 cm. At Application of a previously described embodiment of the invent In accordance with the method according to the invention, it is therefore possible to do this alone Irradiation in the irradiable section of the conveyor path  adequate vulcanization or partial vulcanization of the Ma to cause terials, so that an undesirable deformation of the material after contacting the conveyor direction is avoided.

For non-contact measurement of the surface temperature of the Ma terials the device preferably does not have one sensor coming into contact with the material, in particular a pyrometer, the sensor with a control device is connected to control the radiation flux density of the In infrared radiation and / or the temperature of the radiation source.

It is also proposed: use of an infrared Radiation source for radiant heating to vulcanize material, with at least part of the heating of the material required energy by electromagnetic Radiation from the infrared radiation source onto the material is transmitted and being at least essential, the Erwär radiation effect in the wavelength near infrared.

The infrared radiation source preferably has a temperature radiator, which at emission temperatures of 2500 K or higher, in particular from 2900 K or higher is.

The infrared radiation source is preferably a halo gene lamp.

In a further embodiment, the infrared radiation source a tube emitter with one in a radiation pass casual tube, especially in a quartz glass tube, he stretching filament.  

The infrared radiation source can be used with a reflector Reflection of emitted radiation in the direction of being heated material.

Embodiments of the present invention will now explained in more detail with reference to the drawing. The invention is ever but not limited to these embodiments. The individual figures of the drawing show:

Fig. 1 shows an extrusion device with downstream För dereinrichtung for removal of the extruded Ma materials and with an irradiation device for irradiating the extruded material and

Fig. 2 shows a cross section through an infrared radiation source for irradiating material.

The device shown in FIG. 1 has an extruder 1 from which a profile strand 2 is continuously extruded. Downstream in the production direction is a conveyor device 7 with a funding 6 , in particular a conveyor belt. The conveyor is used to remove the extruded profile strand 2 for further treatment of the material as. The conveying path between the extruder 1 and the conveying device 7 is approximately 4 cm. In this section of the conveyor path, the profile strand 2 does not come into contact with other material. As will be described in more detail, the section 2 is irradiated in this section of the conveying path.

It should be pointed out that the representation of FIG. 1 is to be understood purely schematically. This means in particular that the conveyance of the material emerging from the extruder 1 does not have to take place in a straight or even horizontal direction. Rather, it must be taken into account in practice that the material of the profile strand 2 , which is plastically deformable immediately after it emerges from the extruder 1 , is subjected to a weight due to its own weight. If, due to the elongated shape of the profile strand, the movement in the conveying direction is stabilized to a certain degree, transverse forces nevertheless occur in general, ie forces transverse to the conveying direction. In a special embodiment of the device, however, the promotion of the pro filstrangs from the extruder 1 to the conveyor 7 in the vertical direction, so that no lateral forces occur due to the weight forces. In another embodiment, the Ge weight forces are taken into account when positioning and aligning the extruder 1 and the conveyor 7 , so that on the one hand no undesired deformation of the profile strand between the extruder 1 and the conveyor 7 takes place and on the other hand the profile strand passes through a defined path.

For irradiation of the profile strand 2 , the device shown in FIG. 1 has an infrared radiation source 3 , which emits infrared radiation directly and / or indirectly via reflections of one or more reflectors in the direction of the profile strand 2 . In Fig. 1, a reflector 4 is Darge, which is located on one of the infrared radiation source 3 opposite side of the profile strand 2 . Radia tion, of the infrared radiation source is coming not absorbed by the profiled bead 2, Flektor by the Re 4 in the direction of the profiled bead 2 reflected. Such a beam is shown by way of example with reference numeral 5 . The reflector 4 can in particular have a curved shape, so that from the direction of the infrared radiation source 3 impinging on the reflector surface radiation concentrated on the profile strand 2 is reflected.

In particular, the reflector 4 can also partially extend around the profile strand 2 , so that a strand 2 in particular takes place at approximately uniform irradiation of the surface of the profile. Alternatively, the irradiation of the surface of the profiled bead may not be uniform, but depending on the view of the profile extrusion 2 from different directions reflected radiation on the surface of the Pro filstrangs 2 occur. Depending on the type and shape of the reflector or other reflectors, the desired irradiation profile can be set. Furthermore, not just one but a plurality of radiation sources can be provided, the radiation sources from the perspective of the profile strand 2 being able to be distributed on the same side and / or around the profile strand 2 .

How the radiation profile is expediently set also depends in particular on the cross-sectional profile of the filstrang 2 profile. With relatively simple cross-sectional profiles, the radiation profile is preferably set such that an approximately uniform irradiation of the profile strand 2 takes place all around. Such profile strands can in particular also be completely vulcanized by the radiation.

In contrast, the irradiation of profile strands with irregular cross-sectional profiles, in particular with protruding lips and / or recesses, is preferably such that, seen in the circumferential direction transverse to the conveying direction, a non-uniform distribution of the radiation energy incident on the surface takes place. The Strahlungspro fil is preferably set such that the material of the extruded profile 2 is seen from any location on its surface from up to a certain predetermined material depth or at least up to this material depth or is at least partially vulcanized if the material is the för dereinrichtung 7 reached. This ensures that after contacting the conveyor 7 no undesired deformation of the profile strand 2 can take place, since under certain circumstances plastically deformable areas of the material inside the profile strand 2 are surrounded by an already stabilized covering. In particular, protruding thin areas of the profile strand 2 , such as a continuous lip in the conveying direction, vorzugwei se before contacting the profile stream 2 with the För dereinrichtung 7 so far vulcanized that no plastic deformation can take place in these areas.

Depending on whether or not the vulcanization of the profile strand 2 is caused solely by radiation heating by radiation from infrared radiation sources, further heating takes place, for example as shown in FIG. 1. For this purpose, the conveyor 7 and the funding 6 promotes the profile strand 2 through a continuous furnace 8 , as already known from the prior art be.

In order to control the irradiation of the profile strand 2 by the infrared radiation source 3 , the device shown in FIG. 1 shows a pyrometer 9 which measures the surface temperature of the profile strand 2 or the radiation intensity coming from the surface of the profile strand 2 . A measurement signal is fed via the measurement line 10 to a control device 12 , which in turn controls the infrared radiation source 3 via a control line 11 .

The extrusion and conveying speed for the profile strand 2 is set in the device shown in Fig. 1 vorzugswei se so that the material of the profile strand 2 from the exit from the extruder 1 to come into contact with the conveyor 7 is conveyed for about 1 second . Before preferably, the profile strand 2 over this entire section from the conveyor path until it comes into contact with the conveyor 7 from the infrared radiation source 3 be emits.

Unlike shown in FIG. 1, an infrared radiation source 3 can alternatively or additionally be located on the side of the profile strand 2 on which the material is located which comes into contact with the conveying device 7 . In this case, a reflector arrangement is not necessary, it reflects the radiation in the direction of contacting the material.

The arrangement shown in FIG. 2 has two Röhrenstrahl ler 20 , which can be used instead of the infrared radiation source 3 shown in FIG. 1 or additionally or alternatively at their positions for irradiating a profile strand or on the materials to be irradiated. The tube radiators 20 each have a tungsten thread 22 which extends approximately in the center line of an elongated quartz glass tube 21 (in Fig. 2 perpendicular to the image plane). The tube radiators 20 are arranged in recesses of a reflector body 23 , the recesses also being elongated, corresponding to the tube radiators 20 , and each having a parabolic cross-sectional profile. Instead of a parabolic cross-sectional profile, other cross-sectional profiles can also be used, for example trapezoidal and / or other cross-sectional profiles, which are in particular matched to a further reflector, such as the reflector 4 in FIG. 1, in order to generate a specific radiation profile.

The surfaces of the recesses shown in FIG. 2 and the surface areas extending in the horizontal direction on the underside of the reflector body 23 are designed as reflector surfaces 24 for reflecting NIR radiation.

By varying the electrical current flowing through the wolf ram threads 22 , the temperature of the tungsten threads 22 and thus the spectral position of the radiation flux density maximum and the total radiation power of the emitted radiation is set. The tungsten threads 22 have a low thermal inertia because their mass and thus their heat capacity is low. Divide within a fraction of a second, the full radiation power can be achieved by switching on the electrical current and, conversely, the emission of radiation can be stopped by switching off the electrical current. Suitable, known electronic control devices quickly achieve a temperature value of the tungsten filaments 22 that is constant over time when the current is switched on.

In order to avoid heating the reflector body 23 , it can preferably be actively cooled, ie for example liquid-cooled. Thus, the reflector surface 24 heats up at most slightly and does not contribute significantly to a dead time for the regulation of the radiation flux density. In this way, the radiation flux density of the emitted radiation can be changed quickly in the event of fluctuations in the conveying speed of the profile strand 2 or even when the extrusion process is interrupted and resumed.

Reference list

1

Extruder

2nd

Extruded profile strand

3rd

Infrared radiation source

4th

reflector

5

Reflected beam

6

Funding

7

Conveyor

8th

Continuous furnace

9

pyrometer

10th

Measurement line

11

Control line

12th

Control device

20th

Tube heater

21

Quartz glass tube

22

Tungsten thread

23

Reflector body

24th

Reflector surface

Claims (19)

1. A method for vulcanizing a material ( 2 ), in particular special rubber or silicone, the vulcanization being effected or supported by heating the material ( 2 ), characterized in that at least part of the energy required for heating the material ( 2 ) is transmitted by electromagnetic radiation from a radiation source ( 3 ) to the material ( 2 ), at least essential radiation components causing the heating of the material ( 2 ) being in the near infrared wavelength range. 2. The method according to claim 1, characterized in that the electromagnetic radiation from a radiation source ( 3 ) is emitted, which has an emission temperature of 2500 K or higher, in particular of 2900 K or higher. 3. The method according to any one of claims 1 and 2, characterized in that the material ( 2 ) is selected or prepared such that its degree of absorption in the near infrared has values greater than 0.4, in particular greater than 0.6. 4. The method according to any one of claims 1 to 3, characterized in that the material ( 2 ) not absorbed, reflected radiation components of the electromagnetic radiation are reflected back in the direction of the material ( 2 ). 5. The method according to any one of claims 1 to 4, characterized in that the surface temperature of the material ( 2 ) is set to a predetermined value by controlling the radiation flux density of the radiation incident on the material ( 2 ) and / or the radiation duration. 6. The method according to claim 5, characterized in that the surface temperature at least in a partial area of the material is measured and regulated. 7. The method according to any one of claims 1 to 6, characterized in that the material is elongated and is continuously promoted by egg N irradiation area in which the electromagnetic radiation strikes the material ( 2 ). 8. The method according to claim 8 and according to claim 5 or 6, characterized in that the surface temperature in the irradiation area and / or in the conveying direction behind the irradiation area is measured richly without contact. 9. The method according to any one of claims 1 to 8, characterized in that the material ( 2 ) after at least part of the irradiation with a conveyor ( 6 , 7 ) for conveying the material and / or with a carrier device ( 6 ) for receiving of the weight of the material ( 2 ) is brought into contact, the material region of the material ( 2 ) coming into contact with the conveying device ( 6 , 7 ) and / or the carrier device ( 6 ) being already at least partially vulcanized due to the irradiation. 10. The method according to claim 9, characterized in that the irradiation of the material coming into contact empire not more than 3 seconds, especially not more than 1 second. 11. A device for vulcanizing a material ( 2 ), in particular rubber or silicone with a radiation source ( 3 ) for the emission of infrared radiation, the radiation source ( 3 ) being operable in such a way that radiation-essential portions are in the near infrared, and wherein the radiation source ( 3 ) is arranged such that the material ( 2 ) is at least partially vulcanized due to absorption of infrared radiation. 12. The apparatus of claim 11, with an extrusion device ( 1 ) for extruding the material ( 2 ) in elongated form and with a För dereinrichtung ( 6 , 7 ) for removal and / or for further treatment of the extruded material ( 2 ), wherein the Radiation source ( 3 ) is arranged such that the extruded material can be irradiated before the first contact with the conveyor ( 6 , 7 ). 13. The apparatus of claim 12, wherein the irradiable portion of the conveying path between the extrusion device ( 1 ) and the conveying device ( 6 , 7 ) is not more than 8 cm, in particular not more than 4 cm. 14. Device according to one of claims 11 to 13, with a sensor ( 9 ) for contactless measurement of the surface temperature of the material ( 2 ), in particular with a pyrometer, the sensor ( 9 ) being connected to a control device ( 12 ) for Control of the radiation flux density of the infrared radiation and / or to control the temperature of the radiation source ( 3 ). 15. Use of an infrared radiation source ( 3 , 20 ) for radiant heating of a material to be vulcanized ( 2 ), wherein at least part of the energy required for heating the material ( 2 ) by electromagnetic radiation from the infrared radiation source ( 3 , 20 ) is transferred to the material ( 2 ) and at least substantial radiation components causing the heating of the material ( 2 ) are in the near infrared wavelength range. 16. Use according to claim 15, wherein the infrared radiation source ( 20 ) has a temperature radiator ( 22 ) which can be operated at emission temperatures of 2500 K or higher, in particular 2900 K or higher. 17. Use according to claim 15 or 16, wherein the infrared radiation source ( 3 , 20 ) is a halogen lamp. 18. Use according to any one of claims 15 to 17, wherein the infrared radiation source ( 3 , 20 ) a tube emitter ( 20 ) with a filament ( 22 ) extending in a radiation-permeable tube ( 21 ), in particular in a quartz glass tube. having. 19. Use according to one of claims 14 to 16, wherein the infrared radiation source ( 3 , 20 ) with a reflector ( 22 , 24 ) for reflecting emitted radiation in the direction of the material to be heated ( 2 ) is combined.