CA2441285A1

CA2441285A1 - Method and device for heating and fixing an inking, particularly a toner powder on a plate-shaped support

Info

Publication number: CA2441285A1
Application number: CA002441285A
Authority: CA
Inventors: Bernd Schultheis; Rainer Solbach; Birgit Lattermann; Hans-Jurgen Hommes; Dieter Jung
Original assignee: Individual
Current assignee: Schott AG
Priority date: 2001-03-22
Filing date: 2002-03-21
Publication date: 2002-10-03
Also published as: ATE368877T1; EP1373984A1; DE50210593D1; CN1489721A; US7326443B2; DE10114526A1; DE10114526B4; US20050100812A1; WO2002077720A1; EP1373984B1; CN1317608C

Abstract

The invention relates to a method for heating and fixing an inking, particularly a toner powder on a plate-shaped support, according to which the inking applied to the coated upper side of the support is fixed on the support by heat action. The aim of the invention is to be able to fix toner inkings on thick-walled supports whereby adhering well thereto. To this end, the coated upper side and/or the uncoated underside of the plate-shaped support is subjected to the action of infrared radiation and/or of a hot air stream and/or of a microwave radiation, and a support having a high weight per unit area is used, which permits a portion of the infrared radiation and/or hot air stream and/or microwave radiation directed onto the uncoated underside of the support to pass through while absorbing another portion of the same.

Description

Method and Device for Heating and Fixing an Inking, Particularly a Toner Powder on a Plate-Shaped Support The invention relates to a method for heating and fixing applied ink, in particular a toner powder, on a plate-shaped support, wherein the ink applied to the coated surface of the support is fixed on the support by the application of heat, as well as a device for executing the method.
The use of infrared radiation for heating and fixing an ink application on a paper or a sheet-shaped support is known from DE 198 57 044 Al. The short-wave infrared radiation here has a typical emission temperature of 2000 to 2500 K. Paper has a low weight per surface unit, which is less than 100 g/m2 as a rule.
A further method for toner fixation is known from EP 0 989 473 A2. In this case the toner powder is fixed on the paper by an inductively heated roller.
In this known method, a thin copying paper is heated relatively quickly, since as a rule it also has a weight per surface unit < 100 g/m2. Thick-walled plate-shaped materials, such as glass or ceramic plates, plastic plates, etc. cannot easily be heated up in this way, since they have a clearly higher weight per surface unit and therefore a clearly higher heat capacity.
It is the object of the invention to create a method and a device, by means of which toner powder, in particular ceramic and thermosetting toner powders, can be fixed with good adhesion on plate-shaped materials of high weight per surface unit.
In accordance with the invention, this object is attained by a method which is distinguished in that the coated surface and/or the non-coated underside of the plate-shaped support are acted upon by infrared radiation and/or a hot air flow and/or microwave radiation, and that a support of high weight per surface unit is used, which lets a portion of the action directed to the non-coated underside of the support through and absorbs another portion thereof.
The introduction of energy takes place as needed over the coated surface of the support, as well as the non-coated underside of the support as an action by infrared radiation, a hot air flow and microwave radiation, which can be variably selected. The support lets a portion of the action through and absorbs a portion thereof. Action on the underside of the support causes, for one, the uniform heating of the material of the support because of the partial absorption and, on the other hand, an increased absorption in the toner powder takes place at the interface between the applied ink and the support, which leads to improved melting of the toner powder and therefore also to improved adhesion on the support. The energy introduction is also independent to a large extent of the degree of toner application and of the type of the toner powder, which is particularly advantageous in connection with thermoplastic, thermosetting or ceramic toner powders. The plate-shaped support has a weight per surface unit of > 100 g/m2, in particular > 1000 g/m2.
In accordance with an embodiment it is provided that a transparent material, such as glass, a glass-ceramic material or plastic is used for the support, which has a transmission > 20o, preferably > 50o, in the spectral range of a wavelength of 0.8 :m to 5 :m. Materials of a thickness between 3 and 8 mm and with a relative smooth surface, which is difficult to wet, are particularly suited for this, if a ceramic or thermosetting toner powder is used for the applied ink.
The fixation of the toner powder on such supports can also be improved if the coated surface and/or the non-coated underside of the support are subjected to a hot air flow, which is preferably directed in a focused manner on the applied ink if the support has a reduced transmission degree for this, or also in that the support is subjected to microwave radiation on the coated surface and/or the non-coated underside, whose frequency substantially corresponds to the resonance frequency (microwave coupling frequency) of the molecular structure of the support.
Fixation can take place by means of a device for executing the method while the support is standing still or is being continuously moved, wherein it is provided, for one, that the support provided with applied ink is introduced into a chamber which, on the coated surface and/or the non-coated underside of the support is provided with transmission devices for selectively acting on the support, while on the other hand the process is such that the support can be moved through a pass-through chamber, which is provided with transmission devices for the selective action on the support on the coated surface and/or the non-coated underside of the support.
In accordance with an embodiment, a simple device with infrared radiators arranged on both sides is distinguished in that the transmission devices on the coated surface and/or the non- coated underside of the support are arranged at a uniform spacing, wherein the arrangement on both sides offsets the transmission devices of the surface and the underside by half a space in respect to each other, as well as that several infrared radiators as transmission devices are arranged on both sides of the support, and that the sides of the infrared radiators facing away from the support are enclosed in partial reflectors in the CONFIRMATION COPY

shape of a semicircle.
The infrared radiators extend over the entirety of the applied ink on the stationary support, or they constitute a passage which, by means of the speed of the support and its length, assures sufficient heating and fixation time. The partial reflectors focus the radiation on the applied ink and also direct radiation reflected by the support back to the support. It is possible here to combine the partial reflectors assigned to the coated surface of the support into a reflection unit.
If the support is moved past the infrared beams on a roller track, the device is advantageously embodied in such a way that the partial reflectors assigned to the non-coated underside of the support are respectively arranged between two transport rollers of a roller track.
If the toner powder on the support is additionally subjected to a hot air flow, it is provided that the partial reflectors of the reflector unit are equipped with air flow-through openings and close off inflow chambers, to which hot air can be supplied by means of a hot air blower via feed lines, and that between the partial reflectors the reflector unit delimits suction chambers provided with suction openings, which are connected via suction lines with the hot air blower.
The coated support carp additionally be introduced into a microwave chamber, or can pass through such a chamber, and can be acted upon by a microwave radiation of 2.54 GHz, which is cleared for industrial purposes. This can take place prior to or after the radiation with infrared radiation, or simultaneously with it.
It is a prerequisite in this case that this microwave frequency substantially correspond to the resonance frequency (microwave coupling frequency) of the molecular structure of the support, which is the case in particular in connection with support CONFIRMATION COPY

materials made of an aluminum silicate glass-ceramic material in a high quartz mixed crystal (HQMK) modification.
But an action on the coated surface of the support can also take place by means of only a directed or focused hot air flow. Depending on the material of the support, an action on only the non-coated underside with microwave radiation is also possible.
The invention will be explained in greater detail by means of exemplary embodiments represented in the drawings. Shown are in:
Fig. 1, a pass-through device in a sectional view with a pass-through chamber and infrared radiators arranged on both sides, Fig. 2, the pass-through device in accordance with Fig. 1 with an additional action on the surface by means of a hot air flow, Fig. 3, a device wherein hot air acts on the coated surface, and Fig. 4, a device with a microwave chamber.
The method in accordance with the invention is used with the pass-through device in accordance with Fig. 1, because the support 1 passed through is acted upon on the coated surface 1.1 and the non-coated underside 1.2 by an infrared radiation emanating from infrared radiators 3 arranged on both sides of the support 1. Several infrared radiators with uniform spacing, but offset in respect to each other by half a space, are assigned to the surface and the underside 1.1 and 1.2 of the support 1. The support 1 is moved here by means of transport rollers 2. The speed of this movement and the length of this "pass-through chamber" are matched in such a way that sufficient time for irradiation and fixation is assured. The infrared radiators 3 are each arranged in semicircular-shaped partial reflectors 4.1, CONFIRMATION COPY

or 4.2, so that focusing of the radiation in the direction of the support takes place, and that radiation reflected by the support 1 is reflected back again. The partial reflectors 4.1 on the coated surface 1.1 of the support 1 are combined into a reflector unit 4, while on the non-coated underside 1.2 of the support 1 the partial reflectors 4.2 are always arranged between two transport rollers 2.
The infrared radiators 3 are embodied, for example, as dark radiators, halogen radiators, quartz radiators or carbon radiators, whose radiation maximum lies between 0.8 :m and 5:m, and whose respective emission temperatures lie between 1000 K and 750 K. The thickness of the support can be selected to lie in the range between 3 mm and 8 mm. Glass or glass-ceramic material with a transmission > 200, preferably > 50%, of the short-wave infrared radiation is particularly well suited as the support material. Other materials with a sufficiently large transmission of infrared radiation can be used with an equally good effect.
In a further preferred embodiment the radiators are embodied as ceramic radiators. These have a radiation maximum between 3.5 and 4:m and a radiation temperature in the range between 500 and 600EC.
In the exemplary embodiment in accordance with Fig. 2 the construction with the transport roller 2, the infrared radiators 3 and the partial reflectors 4.1 and 4.2 is identical for all practical purposes. However, for heating and fixing the toner powder on the coated surface 1.1 of the support l, a hot air flow is conducted additionally over the applied ink of the support 1 and is kept circulating in a line system 5 by a hot air blower 6. The partial reflectors 4.1 of the reflector unit 1 enclose inflow chambers 11, which are supplied with hot air via feed lines 5.1. The hot air leaves the inflow chambers 11 by means of air flow- through openings 7 of the partial reflectors 4.1 and CONFIRMATION COPY

additionally heats the applied ink. The reflector unit 4 has suction openings 8 between the partial reflectors 4.1, through which the hot air is aspirated into suction chambers 12. The aspirated air is guided over filters 9 and impurities contained in it are kept back. The air, which has been freed of impurities and cooled, returns via suction lines 5.2 back to the hot air blower 6, where it is again supplied to the circulation 5 after it has been heated and its pressure increased. The action of additional hot air on the applied ink results in an improved heating time, and therefore also toner fixation. The hot air blower 6 can be embodied as a radial blower, which axially aspirates air from the suction lines 5.2 and provides it, heated up, radially to the feed lines 5.1.
As mentioned, the method can also be applied in a device without transport rollers and embodied as a receiving chamber.
The partial reflectors 4.2 are then also combined into a reflector unit, and the support 1 is introduced into the receiving chamber and is subjected to the infrared radiation and/or the hot air flow for a predetermined length of time. The combination of hot air and/or microwave radiation can be selected as needed, wherein the material, the thickness and the transmission degree of the support 1 must be taken into consideration.
In the exemplary embodiment of the device in accordance with Fig. 3, a directed and focused hot air flow 10 acts on the coated surface 1.1 of the support 1. In this case the support 1 is moved past the stationary hot air blower 6 in a housing 15 on transport rollers 2. In this case the air flow generated by the hot air blower 6 is additionally heated by a heater 13, and is conducted in a directed manner via a guide element 14 to an outflow opening 16. Together with the housing 15, the guide element 14 constitutes an outflow conduit 17 and an aspirating CONFIRMATION COPY

conduit 18 for the air flow 10.
A microwave chamber 24 is represented in Fig. 4, wherein the support 2 can be introduced and removed via closing members 25. While the non-coated underside 1.2 of the support is being acted upon, the closing members 25 remain closed. The microwave chamber 24 is shielded toward the outside, so that the microwave radiation only occurs in the inner chamber. Transport rollers 2 take on the transport of the support 1 into and out of the microwave chamber 24. Microwave klystrons 23 are arranged between the transport rollers 2, which are controlled by means of a pyrometer 26. Pyrometers, in particular those which are sensitive in the spectral range of wavelengths around 5.5 :m, or in the range between 7,5 and 8.2 :m, are particularly well suited for monitoring the surface temperature of glass or glass-ceramic materials. Because of the relative good coupling of support materials made of an aluminum silicate glass ceramic material by means of high quartz mixed crystal modification (HQMK), temperature monitoring is particularly important in order to prevent overheating of the toner material and the support material.
Moreover, pyrometers offer the advantage of being relatively insensitive to microwave radiation.
CONFIRMATION COPY
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Claims

Claims 1. A method for heating and fixing applied ink, in particular a toner powder, on a plate-shaped support (1), wherein the ink applied to the coated surface of the support (1) is fixed on the support by the application of heat (1), wherein the coated surface (11) and the non-coated underside (1.1) of the plate- shaped support are acted upon by infrared radiation and/or a hot air flow and/or microwave radiation, and wherein a support (1) of a weight per surface unit of > 500 g/qm is used, which lets a portion of the action directed to the non-coated underside (1.2) of the support (1) through and absorbs another portion thereof, and that a ceramic or thermosetting toner is used for the ink application.

2. The method in accordance with claim 1, characterized in that a transparent material, such as glass, a glass-ceramic material or plastic is used for the support (1), which has a transmission > 20%, preferably > 50%, in the spectral range of a wavelength of 0.8 :m to 5 :m, and an absorption spectrum in the range of a wavelength of approximately 3.2 to 3.8 :m.

3. The method in accordance with one of claims 1 or 2, characterized in that the coated surface (1.1) and the non-coated underside (1.2) of the support (1) are subjected to a hot air flow (10), which is preferably directed in a focused manner on the applied ink, and the support (1) has a reduced heat transmission degree.

4. The method in accordance with one of claims 1 to 3, characterized in a support (1) with a transmission degree > 20%, preferably > 50%, is used.

5. The method in accordance with one of claims 1 to 5, characterized in that a microwave radiation, whose frequency substantially corresponds to the resonance frequency (microwave coupling frequency) of the molecular structure of the support (1), acts on the coated surface (1.1) and/or the non-coated underside (1.2) of the support (1).

6. The method in accordance with claim 5, characterized in that a support (1) made of aluminum silicate in a high quartz mixed crystal modification (HQMK) is employed, on which a microwave frequency of 2.54 GHz acts.

7. A device for executing the method in accordance with one of claims 1 to 6, characterized in that the support (1) provided with applied ink is introduced into a chamber which is provided on the coated surface (1.1) and/or the non-coated underside (1.2) of the support (1) with transmission devices for selectively acting on the support (1).

8. The device for executing a method in accordance with one of claims 1 to 6, characterized in that the support (1) can be moved through a pass-through chamber, which is provided on the coated surface (1.1) and/or the non-coated underside (1.2) of the support (1) with transmission devices for the selective action on the support (1).

9. The device in accordance with claim 7 or 8, characterized in that the transmission devices on the coated surface (1.1) and/or the non-coated underside (1.2) of the support (1) are arranged in a uniform spacing, wherein in the arrangement on both sides offsets the transmission devices of the surface (1.1) and the underside (1.2) by half a space in respect to each other.

10. The device in accordance with one of claims 7 to 9, characterized in that infrared radiators (3), hot air blowers (6) and microwave generators are used as transmission devices.

11. The device in accordance with one of claims 7 to 10, characterized in that several infrared radiators (3) as transmission devices are arranged on both sides (1.1 and 1.2) of the support (1), and the sides of the infrared radiators (3) facing away from the support (1) are enclosed in partial reflectors (4.1, 4.2).

12. The device in accordance with claim 11, characterized in that the partial reflectors (4.1) assigned to the coated surface (1.2) of the support (1) are combined into a reflector unit (4).

13. The device in accordance with claim 11 or 12, characterized in that the partial reflectors (4.2) assigned to the non-coated underside (1.2) of the support (1) are respectively arranged between two transport rollers (2) of a roller track.

14. The device in accordance with one of claims 11 to 13, characterized in that the partial reflectors (4.1) of the reflector unit (4) are equipped with air flow-through openings (7) and close off inflow chambers (11), to which hot air can be supplied by means of a hot air blower (6) via feed lines (5.1), and between the partial reflectors (4.1) the reflector unit (4) delimits suction chambers (12) provided with suction openings (8), which are connected via suction lines (5.2) with the hot air blower (6).

15. The device in accordance with claim 14, characterized in that the hot air aspirated from the suction chambers (12) is returned via filters (9) to the hot air blower (6).

16. The device in accordance with one of claims 14 or 15, characterized in that the hot air blower (6) is embodied as a radial blower, which aspirates the hot air from the suction lines (5.2) and returns it radially to the feed lines (5.1).

17. The device in accordance with one of claims 10 to 16, characterized in that the infrared radiators (3) are embodied as halogen radiators, quartz radiators or carbon radiators, which have a maximum in the radiation spectrum between 0.8 :m and 5 :m wavelength, and a radiation temperature in the range between 1000 K and 3750 K.

18. The device in accordance with one of claims 7 to 16, characterized in that the infrared radiators are embodied as ceramic radiators, which have a maximum in the radiation spectrum between 3.5 and 4 :m wavelength and a radiation temperature in the range between 500 and 600EC.

19. The device in accordance with claim 8 or 9, characterized in that a housing (15) with a hot air blower (6) and a heater (13) is assigned to the coated surface (1.1) of the support (1), which is provided with an outflow opening (16) for the hot air flow (10), the support (1) can be moved past the outflow opening (16), and an outflow conduit (17) and an aspirating conduit (18) are formed by means of a guide element (14) in the area of the outflow opening (16).

20. The device in accordance with claim 8 or 9, characterized in that the support (1) can be introduced into a shielded microwave chamber (24), which can be opened and closed by means of closing members (25), with the closing member (25) closed, the non-coated underside (1.2) of the support (1) can be acted upon by microwave radiation from microwave klystrons (23), and the microwave klystrons (23) can be controlled by means of a pyrometer (26) housed in the microwave chamber (26).

23. The device in accordance with claim 20, characterized in that the microwave klystrons (23) are arranged between trans.