JPS6297845A - Substance treater by ultraviolet ray - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to the treatment of materials with ultraviolet light (hereinafter referred to as U'V), preferably the drying of surfaces coated with U4 lacquer or U'/ink, for example immediately after printing on a rotary printing press. The present invention relates to an apparatus for drying UV inks and for radiation of gases and liquids, consisting of a housing consisting of an ultraviolet source and at least one reflective surface.

In the case of multicolor rotary printing presses, it is necessary to dry the ink applied by the first printing unit before it can be applied by the second printing unit. It has therefore been proposed to place a drying device, which usually consists of an intense heat source, immediately after each printing unit.

Conventional equipment is now increasingly used in the so-called U
Not suitable for drying V-ink. This is because the present drying process is not based on the evaporation of the volatile components of the ink using water as a solvent, but is based on polymerization carried out under the action of ultraviolet light. Therefore, for drying U4 ink, light sources are generally proposed that emit as high a proportion of ultraviolet radiation as possible. In such cases, commercially available quartz mercury lamps are selected, and these mercury lamps are designed to direct as much 560° radiation as possible from the mercury lamp to the printed material of paper, plastic sheet or metal. Surrounded by one or more reflecting mirrors. These reflectors are made from aluminum, anodized aluminum or stainless steel.

In contrast, conventional UV radiation devices not only direct the desired UV radiation directly or indirectly by their reflectors onto selected areas of the printing surface, but also over a large spectral range (approximately 200 There are also defects that direct the total radiation emitted by the radiation source including from 650 to 101,000 nm.High wall temperatures caused by the high proportion of visible and infrared radiation above 400 nm 650 to 8
For 00°C, this results in a high temperature of the printing surface and, depending on the type of material, may lead to expansion of the plastic sheet and moisture-related warping, distortion or scorching of the paper, thus cooling the printing surface. (maximum safe surface temperature is 40°C), various measures must be taken.

Another drawback is that, depending on the configuration and conditions of the reflector, the theoretical proportion of indirect radiation, which can be well above 50%, cannot be directed towards the printing surface as a result of the limited reflective capacity of the reflector material's ability. . 250 nanometers (
nm), the reflection coefficient is 70 for anodized aluminum.
%, it corresponds to 50% for non-anodized aluminum and only 40% for stainless steel.

Another disadvantage to consider is the rate at which these mirrors age. As a result of the action of radiation, heat and, at the same time, steam and gases generated from the printing surface, condensed water and ozone generated when injecting mercury lamps, reflective surfaces corrode very quickly and their reflective ability becomes relatively low. It is meant to be significantly reduced after only a short period of use. Studies and measurements have shown that as a result of hydrogen chloride escaping from UV inks that split under the action of ultraviolet light and heat, thereby releasing chlorine into the atmosphere, hydrochloric acid is formed together with the condensed water, and therefore Corrodes the reflector material. Similarly, vapor from roller cleaners containing trichlorethylene can produce the same effect.

Measurements have shown that the ultraviolet energy required to sufficiently dry or polymerize UV ink on a surface transported at 80 years/min is 9 to 10 watts per square meter, with a minimum value after just 500 operating hours. Descend below. If you do not replace those reflectors, then this device will
The only possibility is to continue operating at a slow processing speed that is completely uneconomical.

It is an object of the present invention to reduce the spectrum of the full range long wave radiation or ultraviolet radiation source so that the ultraviolet radiation is increased, thus increasing the efficiency and useful life of the emitting devices and their reflectors. The aim is to improve the

The achievement of this objective is carried out by means of an ultraviolet emitting device and at least one reflector, whereby at least one surface of this reflector is coated with one or more layers to reflect the ultraviolet radiation of the ultraviolet source and spectra of the ultraviolet source. It has a coating underneath the aforementioned layer that absorbs the long wave range of .

Preferably, the reflector consists of two parabolic or cylindrical half-shells. This is because it is extremely difficult to apply the required coating to surfaces that are highly curved.

The half-shells are preferably hinged relative to each other to properly focus the reflected radiation.

Aluminum or its alloys, copper, brass or steel have been found to be preferred materials for making the parabolic half shell.

The reflective layer applied to the absorbing layer consists of a number of alternating layers of high and low refractive materials which together form a so-called interference filter.

Elox, black chrome, anodized, black nickel and polished glaze have been found preferred for providing the absorbent layer.

The radial or ellipsoidal half shell is preferably comprised of an aluminum alloy commercially available under the trademark Polyden Extrudal 50g. The absorption layer preferably consists of several layers of copper and nickel, each or one of which is polished and then applied to a previously polished aluminum surface.

The polished nickel layer is plated with black chrome.

Preferably, a diffusion barrier layer having a physical thickness of at least 15μ is provided between the absorption layer and the reflection layer.

Preferably this diffusion barrier layer consists of 5 iol.

This is because sio behaves unfavorably with respect to the optical surface and furthermore does not require a coating material different from existing ones.

It is preferable that the parabolic half-shell be made from 50 g of extrudal made of a continuously cast hollow part.
The cavities are connected to a cooling device.

The UV radiation device, consisting of two parabolic half-shells around a quartz mercury lamp, is preferably provided with a cover with a downward opening through which ultraviolet radiation passes.

Advantageously, this cover is made of quartz glass.

It is also preferred to fit an opaque cover over the lower opening of the UV radiator so as to quickly cover the opening in order to block the radiation if the line is to be suddenly stopped. In addition, to ensure that no dust, vapors or gases accumulate on the reflector, the quartz glass can be removed by supplying dry and concentrated air or inert gas in a closed or open circuit with a slight overpressure. It has been found preferable to ventilate the interior of the device with a cover.

To further explain the invention, reference is made to exemplary designs of the invention as illustrated in the accompanying drawings and diagrams.

In the graph of FIG. 1, for a particular material width and material speed of 80 US/min, the minimum value of UV radiation required per surface squared to be dried is shown as 9 to 10 W. As shown in the two lower curves representing the radiation dose of conventional UV radiators, the minimum value is no longer reached even after exactly 4001 conversion times due to the reduction of the UV reflection of the reflector as a result of corrosion. . The upper curve shows the radiation dose emitted by the device according to the invention. 25
Even at 00 hours of operation, this curve is clearly above the minimum value. However, the decrease in radiation dose in this case is not due to corrosion of the reflector, but is due to a decrease in the output of the quartz mercury lamp.

In the diagram of FIG. 2, the conventional UV radiation devices A and B are compared with the device according to the invention with respect to their efficiency! ! Compared to LC, the total UV radiation of device C is shown as 100%.

UV radiator A achieves only 57% of the radiation of C;
Radiation device B records only 71%. The indirect radiation of A is only equal to 10% due to the poor reflection of the reflector, while the direct radiation of the quartz mercury lamp accounts for 27%. As a result of the poor efficiency, two type A radiators must be placed in series to achieve the required power.

The performance of radiator B is relatively good at 71%, with indirect radiation accounting for 37.5% and direct radiation accounting for 355%. Overall, it shows poor results when considering the useful life of the UV emitting device B. This is because the overall performance reduction is particularly large as a result of the high proportion of indirect radiation, and the performance reduction mentioned above is due to reflector corrosion.

In the case of device C according to the invention, the performance ratios for direct versus indirect radiation are almost equal, but do not result in any appreciable reduction with respect to indirect radiation. This is because the reflector is practically not subject to wear or corrosion. One fundamental advantage of the device according to the invention lies in the fact that: That is, the radiation source can be placed relatively close to the material strip for a significant reduction in the visible and infrared radiation, to the point that the effect of the ultraviolet radiation can be increased.

FIG. 3 shows the comparison illustrated in FIG. 2 with respect to infrared light, thus taking 100% infrared light as the basis for device C according to the invention. In this example, the efficiency of the absorption layer according to the subject of the invention is evident. While the proportion of indirect radiation for C amounts to only 24%, the proportion of indirect radiation for A is equal to 68% and is recorded at 122% for the total infrared radiation compared to C.

Since two radiators of type A are required for effective drying, this then results in a doubling of the infrared fraction to 245% and the indirect fraction to 156%. Based on the basis of comparison to ultraviolet light, it is also clear that conventional reflectors reflect relatively more infrared light than ultraviolet light. This means that a large share of ultraviolet light (approximately 50 to 40%) is not reflected.

In the case of ultraviolet radiation device B, this relationship becomes even worse. Compared to C, the total infrared radiation is equal to about 171%. Indirect infrared radiation increases by more than 100%. In this example, it is also clear that the indirect infrared rays are larger than the indirect ultraviolet rays.

The diagrams in FIGS. 7 and 8 show the effect of ultraviolet and infrared radiation when the mirror shells are placed at different angles to each other (7, 5° and 20°).

It is well known that the drying of UV printing inks depends relatively less on the exposure time and relatively more on the ability of the UV radiation to penetrate into the ink layer. Comparisons show that by tilting the half-shell at 20° and focusing the ultraviolet radiation, it is possible to generally increase the radiation intensity. Due to the considerably improved infrared absorption K, which even when focused is still less than the value shown in FIG. 2 for the UV emitting device B, the distance between the radiation source and the printing material is therefore 20% less than for dryers.

If you try to focus a conventional UVi dryer, it will reach such high temperatures that the printing material will burn and become a flame.

According to the invention, the apparatus (1) shown in FIG.
It consists of a table (4) that is pulled in a minute and is also held hinged. In the upper part of the no-using (2) there is a quartz mercury lamp (6) which can be easily replaced. Furthermore, the two parabolic half-shells (7 and 7I) are
2) is attached. “Extrudal 50I
The hollow continuous cast part made of aluminum is provided with a plurality of conduits (8) through which a coolant, such as water or a similar substance, is passed. The lower opening of the housing (2) is covered by a quartz glass plate (9). At the bottom of the quartz glass plate (9) there is a shutter (10) which can be quickly pulled out in front of the quartz plate (9) if the printing process is interrupted by means of suitable control schemes and devices, not shown in this case. There is.

A parabolic half-shell (
The surfaces of 7 and 7') each have an absorption layer (11) made of polished steel and a nickel coating and plated with black chromium.

Tests have shown that, with respect to all those parameters, black chrome plating on pultruded continuous cast parts of Tortoise Extrudal 50t aluminum alloy provides the best results, although it does not necessarily mean achieving the best 04 reflector. is obtained. The absorbing layer (11) not only ensures good absorption of infrared radiation, but also provides a good basis on which the vapor-deposited quartz layer can bond to the reflective layer (12). A reflective layer is applied to the black chrome plating of the pultruded aluminum surface. After the black chrome plating process their surfaces are matte and unstructured, thereby providing a good basis for bonding, while for example nickel plating only provides extremely poor bonding.

The reflective layer (12) consists of a total of 66 individual Ia layers, of which the odd-numbered layers consist of hafnium dioxide and the even-numbered layers consist of silicon dioxide. Each one of these layers has a certain thickness that can be expressed as a multiple of λ/4, where λ is in this example 35
One so-called reference wavelength I is equal to 0 nm. The multiple of λ/4 is, for example, an integer (e.g. 1.00)
in the case of multiple layers, these are equal to less than or equal to 1.00, and only the last (66th) layer is greater than or equal to 1.00, ie 1.36.

The resulting reflection curve (FIG. 6) is in the range 250 to 400
It is quite clearly shown that in nm the layer system exhibits a reflection maximum defined by an abrupt edge.

In order to create a reflective layer, “Extrudal 50I Al
The reflector half shell, which is made from a continuous casting part that is black-plated with aluminum alloy, is manufactured using vapor deposition equipment model 1100 (
Manufacturer: West Germany, Leibold Hellaois GmbH, Germany) was placed on an internal support holder. This device is
The pressure was evacuated to 10 pa within 6 minutes. The supports were then cleaned in the usual way by means of a glow discharge. Following this, the apparatus was evacuated within a further 30 minutes at a pressure of 5×10 pa4 and their supports were heated to 260° C., after which a pressure of 2×1 G=p
Oxygen was supplied as a diffusion gas until the temperature reached a.

After that, nounilum dioxide (H
Fo Yuki) is heated 2 times with an electron beam gun until the pressure stabilizes.
Following this, HfO! was deposited as first coat and binder at an evaporation rate of t5 nm/sec. The known oscillating crystal method is applied to adjust the evaporation rate and control the diaphragms, which can be rocked onto the evaporator and by which the evaporation process for each coat can be interrupted. . HfO,
Following the layer 15i (layer 11 has an evaporation rate of 1.0 nm)
It was deposited using a separate electron beam gun for 7 seconds, whereby the HfO was kept at a sufficiently high temperature by supplying a small amount of energy. Once the diaphragm to the 8 i 09 evaporator is closed, the evaporator is maintained at a high temperature as well by supplying a small amount of energy;
And HfO! The electron beam gun for evaporation (C) was again raised to evaporation power. A total of 66 independent layers were deposited by alternating repetition of this coating procedure.
Each of the layers has a thickness equal to a reasonable multiple of λ/4, where λ is the so-called reference wavelength chosen at 350 nm for the purpose described here in m-*.

The multiples of λ/4 mentioned above are from the 2nd layer to the 65th layer (16
It varies from 6 to 1.00. The number is CL for the first layer
Equal to J6 and equal to t56 for the 66th layer of Sing.

The pressure in the vacuum chamber was kept constant during the entire process. Once the dosed layer has been applied, the evaporator is shut off and allowed to cool for 5 minutes. The system was then filled with water. Measurements made on the reflection behavior cover the wavelength range of interest 25
This resulted in the curve of FIG. 6 showing excellent reflection behavior defined by a steep edge from 0 to 400 nm. This layer system adheres very well, without cracks and has a reading of 87-97% (reflection) over the entire range.The reading in the infrared was only about 5%.

[Brief explanation of drawings]

FIG. 1 is a graph showing a comparison of efficiency between a radiation device according to the present invention and a conventional UV radiation device; FIG. FIG. 3 is the same as FIG. 2, but with regard to infrared efficiency, FIG. 71114 is a side view of the device according to the invention;
Figure 5 is a cross-sectional view of the coating on the parabolic half-shell surface;
FIG. 6 is a detailed view of the reflective layer* (in %) with respect to wavelength; FIGS. 7 and GA are diagrams showing the radiation intensity of ultraviolet and infrared radiation in half-shells at different angles with respect to each other.

Claims (1)

[Scope of Claims] 1. An ultraviolet radiation material treatment device comprising a housing containing an ultraviolet source and at least one reflector, comprising:
At least one reflector surface has one or more coatings (12) for reflection of ultraviolet radiation of the ultraviolet source (6) and a coating (11) underlying said coating for absorption of the long wave part of the spectrum of the ultraviolet source (6). ). 2. Device according to claim 1, characterized in that the reflector consists of two parabolic or ellipsoidal half-shells (7 and 7'). 3. Device according to claim 2, characterized in that the parabolic or ellipsoidal half-shells (7 and 7') are arranged hingedly to each other. 4. Device according to claim 2, characterized in that the parabolic or ellipsoidal half-shells (7 and 7') are made of aluminum or its alloys, copper, brass or steel. 5. Device according to claim 3 or 4, characterized in that the parabolic or ellipsoidal half-shells (7 and 7') consist of an aluminum alloy known as "Extrudal 50". 6 the reflective layer (12) consists of several separate layers, the layers consisting of alternating high and low refractive insulators;
Regarding the reference wavelength input of 0 nm, the layer thickness is about 1/4 of the wavelength, so the reflection reading is within the wavelength range of 250 to 40 nm.
The device according to claim 1, characterized in that the radiation density is basically 80% or more with respect to 0 nm. 7. Device according to claim 6, characterized in that the UV-reflecting coating consists of a low-refraction insulating layer SiO_2 and a high-refraction insulating layer HfO_2, which are deposited alternately by a vacuum coating method. 8. Device according to claim 7, characterized in that the layered structure starts with a high-index insulating layer and ends with a low-index insulating layer. 9. Device according to claim 8, characterized in that the layers are deposited at a reflector temperature of 100 to 500°C, preferably 120 to 200°C. 10 Absorption layer (11) is black Erotx, black chrome,
2. Device according to claim 1, characterized in that it is made of black nickel, anodized or polished. 11 The absorption layer of the parabolic or ellipsoidal half-shell (7 and 7') attached to the polished surface of the half-shell is a polished steel coating;
11. Device according to claim 10, characterized in that it comprises a nickel coating and a black chrome plating layer. 12. Claim 6 or 1, characterized in that the diffusion-blocking coating is placed between the absorbing coating (11) and the reflective coating (12) and consists of an insulator with a physical thickness of at least 0.5 μ. The device according to item 10. 13. Device according to claim 12, characterized in that the diffusion barrier layer consists of SiO_2. 14. Device according to claim 4, characterized in that the parabolic half-shells (7 and 7') are provided with a cooling device for dissipating the absorbed heat. 15. Device according to claim 5, characterized in that the parabolic half-shells (7 and 7') consist of continuously cast hollow sections, the cavities of which are connected to a cooling device. 16. Device according to claims 1 to 15, characterized in that the lower opening oriented towards the printing material (5) is fitted with a UV-transparent cover (9). 17. Device according to claim 16, characterized in that the cover (9) consists of quartz glass. 18. Device according to one of claims 1 to 17, characterized in that it is fitted with an interlocking cover (9) whose opening directed towards the printing material is opaque to radiation. 19 Claim characterized in that the device, which is shut off by a quartz glass cover (9), is connected to a closed ventilation device, through which drying and filtered air or drying and filtered inert gas is circulated. The device according to item 1. 20. Claim 1, characterized in that the inside of the device, which is shielded by quartz glass, is connected to an open ventilation system, through which dry and filtered air is supplied to the inside under a slight overpressure. Apparatus described in section. 21 Paper, plastic or metal strip material
Claim 1 for drying and curing V ink
Application of the device according to item 1 of item 20.