Poul
Schack
Aps Petersen, Poul Schack
| 1. | A waterbased printing dye, preferably a covering printing dye and preferably for textile printing, which printing dye is intended for setting at least the surface of the printing dye to a setoff free state by cooling to a temperature below a phase transitional tempera¬ ture for the dye, c h a r a c t e r i z e d in that substantially the entire dye mixture has a common transformational curve up to the phase transitional temperature, and that the phase transitional temperature is above 40°C, preferably above 25°C, especially above 10°C. |
| 2. | A printing dye according to claim 1, c h a r a c t e r i z e d in that the dye has such a mixture that at least the surface of the printing dye during a succeeding printing sequence is not raised to a temperature exceeding the phase transitional temperature. |
| 3. | A printing dye according to claim 1 or 2, c h a r a c t e r i z e d in that the printing dye contains swelling balls with a diameter of between 5 μm and 20 μm in an expanded state. |
| 4. | A printing dye according to any one of the preceding claims, c h a r a c t e r i z e d in that the printing dye contains particles, which are heat and light reflective. |
| 5. | A printing dye according to any one of the preceding claims, c h a r a c t e r i z e d in that the printing dye contains an agent for changing the phase transitional temperature of the dye to a level, which is different for printing dyes that form part of a multicolour print. |
| 6. | A method for multicolour printing with a printing dye according to any one of the preceding claims with intermediate cooling for at least to set the surface of the printing dye to a setoff free state, c h a r a c t e r i z e d in that the cooling time is less than 15 se conds, preferably less than 10 seconds, and especially less than 5 seconds. |
| 7. | A method according to claim 6, c h a r a c t e r i z e d in that the cooling is carried out by contact cooling with a plate having a temperature, which is not below 60°C, preferably not below 40°C. |
| 8. | A method according to claims 6 or 7, c h a r a c t e r ! z e d in that at least the surface of a printing dye is kept at a temperature below the phase transitional temperature for a printing dye applied during one or several succeeding printing sequence(s). |
The present invention relates to a water-based printing dye, preferab¬ ly a covering printing dye and preferably for textile printing, which
* 5 printing dye is intended for setting at least the surface of the printing dye to a set-off free state by cooling to a temperature below
% a phase transitional temperature for the dye.
E.g. from International Patent Application published under no. WO 92/- 10 14610 it is known to use a freezing technique in multicolour printing, preferably textile printing, and preferably covering textile printing, in which printing dyes are applied successively, and in which the vis¬ cous printing dyes between each print are cooled in order to obtain a set or set-off free state before or during the application of succeed- 15 ing printing dyes.
Common water-based printing dyes have been used earlier. This had been disadvantageous as it is very energy consuming, and it is necessary to use very low temperatures in order to ensure that an applied printing
20 dye at a succeeding printing sequence is not brought into a viscous, set-off state. Thus, there had been need for both using large amounts of energy and at the same time having the printing sequence proceeding relatively slow in order to obtain the very low temperatures, even when using contact cooling, which is made by direct contact between
25 the applied printing dye and cooling agent.
Thus, it is essential that a setting is obtained, at least in the sur¬ face of a printing dye in order to avoid that the dyes mix or set off during and after the application of a succeeding printing dye. 30
The known water-based printing dyes are provided with absorbent means, softeners, or like means and other additives, which are used for ob¬ taining the desired features in the printing dye. These different ad- ι ditives may make the mixture inhomogeneous as some of the additives
35 are not fully soluble. E.g. this is the case with certain glycols,
* which are used as absorbent means.
However, up to now these inhomogeneous printing dyes have been accep¬ ted as very low temperatures have been used. However, with due regard
to the energy consumption, it is disadvantageous to freeze the print¬ ing dye to the very low temperatures in order to avoid that certain additives occur in a viscous state.
It is the object of the present invention to show a printing dye of the above-mentioned type, which remedies the drawbacks of the known printing dyes, and which thereby makes it possible to maintain a high printing sequence without risk of the properties of the dye being des¬ troyed.
According to the present invention this is obtained in that substan¬ tially the entire dye mixture has a common transformational curve up to the phase transitional temperature, and that the phase transitional temperature is above -40°C, preferably above -25°C, especially above -10°C.
By composing the dye in such a way that substantially the entire dye mixture has a common transformational curve up to the phase transi¬ tional temperature, it is possible to eliminate the risk that any com- ponent appears in a viscous state below the phase transitional temper¬ ature. The phase transitional temperature may advantageously be de¬ fined in advance in order to be within a temperature interval, which does not require great amounts of energy in order to effect the free¬ zing. A phase transitional temperature, which is about or above -40°C, will be advantageous as this level of temperature may be obtained by using traditional compression cooling plants and by using Freon cool¬ ing agents. By using phase transitional temperatures above -25°C or above -10°C, it has appeared possible to maintain the printing dyes in their set-off free state during succeeding printing sequences and by using intermediate freezing, which takes place by bringing a contact plate in direct contact with the viscous printing dye.
An advantageous embodiment for the printing dye contains swelling balls having a very small diameter of between 5 μm and 20 μm in an expanded state. By using such small swelling balls it is possible to produce the dye with reduced use of chemical softeners, which influ¬ ence the freezing properties. Furthermore, the swelling balls in the individual printing dyes are kept frozen so that a swelling will not occur until the finished multicolour print in a well-known manner, is
dried at heating. Consequently, a soft, flexible, and extensible covering dye may be produced without a particular relief-effect ap¬ pearing in the colour print. Furthermore, the swelling balls may give a better covering dye when the swelling balls used expand at low tem- peratures before finishing the final film in the dye. The better covering is obtained because the liquid in the dye may pass through the coat of dye to the surface. Consequently, the transparency of the colour print is reduced.
Furthermore, the printing dye according to the invention is advanta¬ geous as it may contain light and heat reflective particles. According to the invention the printing dye may thus be used for forming mul¬ ticolour prints with a reflective effect in one or several of the dyes. As the dye may be set at cooling, it is possible to maintain a high printing sequence, which cannot be obtained by normal heat set¬ ting. The heat setting of paint with light and heat reflective par¬ ticles will cause unreasonable, long printing sequences.
An embodiment for the printing dye according to the invention may con- tain a mean for changing the freezing or glass point temperature in one or several of the printing dyes used. Such a mean may e.g. be al¬ cohol .
The invention also relates to a method for printing with a printing dye according to the invention with intermediate cooling for at least to set the surface of the printing dye to a set-off free state, char¬ acterized in that the cooling time is less than 15 seconds, preferably less than 10 seconds, and especially less than 5 seconds.
Surprisingly, it has appeared to be possible to effect a setting at least in the surface of the printing dye by cooling, without the prop¬ erties of the printing dye, e.g. gloss, adherence, and cohesion, being destroyed. This has appeared to be possible when the cooling takes place very quickly, and preferably momentarily. It has not been pos- sible to give an explanation to this, but it is assumed that during the very quick cooling large crystals cannot be formed, which might have changed the properties of the printing dye by a succeeding thaw¬ ing.
The quick cooling is preferably carried out by bringing a plate in direct contact with the viscous print. Because of direct contact cool¬ ing a very quick heat transition appears, and therefore it is possible to carry out the cooling with a plate temperature, which is not below -60°C, and which preferably is not below -40°C. The contact cooling used is preferably of the type described in the above-mentioned inter¬ national patent application. It is noted that the freezing agents and the printing machines, which are described in the international patent application, may be used in connection with the present invention, and are hereby incorporated with reference.
It is noted that the temperatures used do not necessarily need to be minus degrees. Thus, the phase transitional temperature, in which a setting appears, may also be a positive temperature, and tests have been made with printing dyes, which have been set-off free at tempera¬ tures up to +5°C.
Description of the Drawing.
The accompanying drawing illustrates an example of a transformational curve of a printing dye according to the invention.
The transformational curve is common for substantially the entire dye mixture in an area 2 up to an area 3 of the phase transitional temper- ature of the dye. The sequence 4 of the transformational curve 1 at temperatures above the phase transitional temperature 5 is of less importance. The time 6 in which the phase transitional temperature appears, is an expression of how long time the dye maintains the same temperature when it undergoes a phase shift from a solid state to a liquid state. It is noted that the abscissa provides the time in se¬ conds, and the ordinate provides the temperature in °C.
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