JPH0551637B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to ink for inkjet printers, and more particularly to an ink composition for inkjet printers that has excellent heat resistance. (Prior Art) An inkjet printer is a non-impact type printer that records characters and figures by ejecting ink droplets from a nozzle to form ink dots on a printing surface. Inkjet printers are used as printers for office automation equipment because they can be made smaller, have a smaller driver, and have faster printing speeds.They also have other advantages such as being able to print on non-flat surfaces and printing in color. As a result, its uses are expanding. Ink jet printers eject ink using two methods: (a) a continuous method that creates ink droplets by applying vibration to a continuous jet of ink; (b) an on-demand method that creates ink droplets only when necessary by generating pressure pulses; ) The electric field control method uses an electric field to eject and stop ink droplets, and (d) the ink mist method uses ion flow to control the atomized ink. The properties required of ink for such inkjet printers include a viscosity and surface tension suitable for forming normal ink droplets, a colorant particle size that does not clog the ink jet nozzle, and stable dispersion. It must satisfy more conditions than inks for conventional impact printers, such as electrical conductivity and conductivity suitable for controlling the direction of ink ejection using an electric field. Many inks for inkjet printers satisfying these conditions have been proposed, and some have already been put into practical use. Initially, water-based inks were the main type, but solvent-based inks have also been developed to improve the water resistance of printed materials and to print on materials other than paper, such as metal, glass, and plastic. (Problems to be Solved by the Invention) However, all conventional inks for inkjet printers adhere coloring agents such as dyes and pigments to the printing surface using a resin binder, and have poor heat resistance. Not considered at all.
Therefore, if printed matter is exposed to high temperatures during the processing process or during use after processing, the ink may change color due to deterioration of the dye or resin, or the colorant may fall off due to decomposition of the binder.
Conventional inks for inkjet printers have problems that make them unsuitable for printing printed materials that are exposed to high temperatures. Therefore, the present invention is an attempt to solve the above-mentioned conventional problems, and even if the printed matter is exposed to high temperatures where the colorant and binder contained in the ink will discolor and decompose, it will not be possible to improve the visibility. An object of the present invention is to provide a heat-resistant ink for an inkjet printer that has good adhesion to printed matter. Another object of the present invention is to provide a heat-resistant ink for an inkjet printer that does not clog the ink ejection nozzles of the inkjet printer and has good conductivity. (Means for Solving the Problems) The means of the first invention is an ink for an inkjet printer containing a glass component having a pigment color, a solvent, a binder, and a conductivity imparting agent, which It is said to be a heat-resistant ink containing a hydrolyzed solid of metal alkoxide as a component.
The colored hydrolyzed solid of the metal alkoxide is fine particles with an average particle size of 0.6 m or less and a maximum particle size of 2 μm or less, and the melting point of the fine particles is within the heat-resistant temperature range of the printing material. The means of the second invention is an ink for an inkjet printer containing a pigment, a pigment dispersant, a glass component, a solvent, a binder, and a conductivity imparting agent, wherein the glass component is a hydrated metal alkoxide. It is said to be a heat-resistant ink containing decomposed solids. In the second invention, the pigment is fine particles having an average particle size of 0.6 μm or less and a maximum particle size of 2 μm or less. The hydrolyzed solid material of metal alkoxide is fine particles having an average particle size of 0.6 μm and a maximum particle size of 2 μm or less, and the melting point of the fine particles is within the heat-resistant temperature range of the printing material. The ink (ink composition) according to the present invention has a glass component, a solvent, a binder, and a conductivity imparting agent as basic main components, and a surfactant, a rust preventive, etc. can be added as necessary. Both of the present inventions are characterized in that a solid product produced by hydrolysis of a metal alkoxide is used as the glass component. This produced solid material melts into a glassy state at high temperatures, and its melting point is selected and used within the range of about 400°C to 1600°C, although it varies depending on its components. This produced solid substance is used as an ink component either as a solid substance itself or in the form of a sol containing a prepared solvent containing the solid substance. Since this solid product is made by hydrolyzing metal alkoxide, it is easy to adjust the particles by adjusting the hydrolysis treatment conditions, and it is possible to reliably obtain fine particles that will not clog the pores of the ink jet nozzle of an inkjet printer. be able to. In addition, the hydrolyzed solids of metal alkoxides are
If a colored hydrolyzed solid is used, as it is sufficiently colored to become a pigment itself, there is no need to add a pigment. Incidentally, if this hydrolyzed solid does not exhibit a sufficient direct color, a fine particle pigment that does not clog the ink ejection nozzle pores is blended as in the past. The fine particles of the glass component used in the present invention, ie, the fine particles of the hydrolyzed solid of metal alkoxide, must basically have a melting point that does not exceed the heat-resistant temperature of the printing material. This is so that the glass component melts within the heat-resistant temperature range of the printing material and is able to adhere to the printing material after cooling. The glass-based component is printed at room temperature and then heat-treated at the melting temperature of the glass-based component. However, it is not good if the melting temperature of the glass component is too low. This is because if the printed matter is exposed to an atmosphere at a temperature higher than the melting temperature of the glass component, the printed dots will flow or bubble, making the printed matter unclear. For this reason, it is desirable that the melting point of the glass component be higher than the heat-resistant temperature required for printed matter, or at least within about 50°C. In such a case, the printed dots may partially melt in the temperature atmosphere to which the printed material is exposed, but the dots do not become disorganized and the printed material becomes clear and strong again at room temperature. As the pigment, for example, the usual pigments shown in the following table are used in the form of fine powder.

[Table] For inkjet printers, for example, diameter number + μ
Since recording is performed by ejecting ink from a nozzle of about 100 m in diameter, the particle size of the glass component or pigment is particularly taken into consideration in order to prevent troubles due to nozzle clogging. Typical solvents used in the present invention include alcohol solvents, ether solvents, ester solvents, ketone solvents, and aromatic solvents; 1 type or 2 types depending on the nature
Preferably, it is prepared as a mixture of more than one type of solvent. The binder used in the present invention may be any resin used in conventional inkjet printer inks, but is soluble in the solvent used in the present invention and is compatible with metals other than paper, glass, ceramics, etc. Those with excellent adhesiveness and durability are preferred. Examples include binders such as acrylic resins, phenolic resins, and rosin-modified resins, but the binders are not limited to these. The blending range of ink components to satisfy various conditions as an ink for inkjet printers, such as ink nozzle jetting properties, adhesion to steel plates, etc., print adhesion, and visibility, is approximately as follows. . That is, in the first invention, glass components (1) to (40) parts by weight solvent (40) to (97) parts by weight binder (2) to (20) parts by weight conductivity imparting agent (0.2) to (5) ) parts by weight In the second invention, pigment (5) to (25) parts by weight glass components (1) to (35) parts by weight solvent (40) to (97) parts by weight binder (2) to (20) Part by weight Conductivity imparting agent (0.5) to (5) Part by weight The content of the binder is preferably in the range of 2-20% by weight based on the ink composition, but it is important to ensure jetting stability from the ink jetting nozzle and optimal The optimum amount is determined from the point of view of ink dot formation. (Function) In the first invention, the hydrolyzed solid of metal alkoxide is a colored glass-based component, and has the functions of both pigment and ink fusion. In the second invention, the hydrolyzed solid material of metal alkoxide mainly functions to fuse the ink. The hydrolyzed solids in both inventions have a sufficiently high heat resistance and are fine particles suitable for ink jet nozzles. (Example) Next, an example of the present invention will be shown. Note that the present invention is not limited to the following examples. Example 1 First, a sol of glass-based components is prepared. The sol of Example 1 is a white 10Na ₂ O−20B ₂ O ₃ solid.
It contains −10TiO ₂ −60SiO ₂ and is produced by the following steps. Ethyl orthosilicate dissolved in ethanol and aqueous ammonia dissolved in ethanol (ammonia is
Si and the same mole) are heated to reflux for 5 hours in a predetermined container equipped with a reflux condenser. Next, metal alkoxides such as sodium methylate, triethylborate, and titanium tetraisopropoxide are added to the container together with a predetermined amount of ethanol, and reflux is continued for 2 hours. After that, a mixed solution of water (3 times the mole of the above alkoxide) and ethanol was added, cooled to room temperature, and stirred for 1 hour to form a sol in which white solids were dispersed (solid content concentration 10%,
The average particle diameter was 0.1 and the maximum particle diameter was 0.5 μm). Next, 100 parts by weight of methyl methacrylate and 12 parts by weight of azobisisobutylnitrile are mixed into 200 parts by weight of ethyl alcohol and polymerized to obtain an acrylic resin varnish having an average molecular weight of 45,000. 2 parts by weight of this varnish (acrylic binder resin), 80 parts by weight of the sol obtained from the above process, and 0.4 parts by weight of lithium nitrate as a conductivity imparting agent were sequentially blended and mixed to give a viscosity of 5.2 cp and a surface tension of 25 dyne/cm. specific resistance
An ink of 880 Ωcm (all values at 20°C) was obtained. When a printing test was carried out on a steel plate using this ink using a charge control type inkjet printer, the jetting characteristics were good, the adhesion to the steel plate was good, and the printing on the steel plate was clear. Next, this printed matter was heated in air at 800° C. for 30 minutes, and then cooled to room temperature, whereupon the printed dots were completely fused onto the steel plate and had good visibility.
Further, even when this printed matter was heated to 600° C. again, there was no disturbance in the printing. Example 2 First, a sol of glass components is prepared. The sol of Example 2 is a white 35PbO−10Na ₂ O as a solid.
-15B ₂ O ₃ -10TiO ₂ -30SiO ₂ It contains a composition of the type, and is produced by the following steps. Ethyl orthosilicate dissolved in ethanol and ammonium water dissolved in ethanol (ammonia is equimolar to Si) are heated to reflux for 5 hours in a specified reflux container. Next, lead acetate, isopropyl alcohol, xylene (solvent), and metallic sodium were heated to reflux for 4 hours to prepare lead isopropoxide, and the lead isopropoxide, sodium methylate, and triethyl were placed in a container. Metal alkoxides such as borate and titanium tetraethoxide are added together with predetermined amounts of ethanol, and reflux is continued for 2 hours. After that, a mixed solution of water (3 times the mole of the above alkoxide) and ethanol was added, cooled to room temperature, and stirred for 1 hour to form a sol in which white solids were dispersed (solid content concentration 10%, average particle size 0.1). , maximum particle size 0.5 μm). Next, in the same manner as in Example 1, 2 parts by weight of the binder (varnish), 80 parts by weight of the sol obtained from the above steps of Example 2, and 0.4 parts by weight of lithium nitrate were sequentially blended and mixed to give a viscosity of 3.9 cp and a surface tension of 3.9 cp. An ink with a specific resistance of 26 dyne/cm and a specific resistance of 780 Ωcm (all values at 20°C) was obtained. When a printing test was carried out on a steel plate using this ink, the results were as good as in Example 1, and the printing on the steel plate was clear. Also, prints can be placed in the air for 600 minutes.
℃ for 30 minutes and then cooled to room temperature. As in Example 1, complete fusion was achieved and visibility was good. Furthermore, the printed matter was heated to 400°C again, but there was no disturbance in the printed matter. Example 3 First, a sol of glass components is prepared. The sol of Example 3 contains colorless 20Na ₂ O− as a solid.
It contains a 2OB ₂ O ₃ -60SiO ₂ based composition and is produced through the following steps. Ethyl orsilicate dissolved in ethanol and ammonia water dissolved in ethanol (ammonia is Si
(equivalent mole) is heated to reflux for 5 hours in a predetermined container for reflux. Next, metal alkoxides such as sodium methylate and triethylborate are added to the container together with a predetermined amount of ethanol, and reflux is continued for 2 hours. After that, a mixed solution of water (3 times the mole of the above alkoxide) and ethanol was added, cooled to room temperature, and stirred for 1 hour to form a sol in which solids were dispersed (solid content concentration 10%, average particle size 0.1, maximum A particle size of 0.5 μm) was obtained. Next, white pigment powder (manufactured by Teikoku Kako KK, fine particle titanium oxide MT-500B (average particle diameter approximately 35 m) was used.
μ) 20 parts by weight, pigment dispersant (manufactured by NOF KK,
Polystar A-1060, anionic surfactant)
0.1 part by weight, sol 40 obtained by the above steps of Example 3
parts by weight, 0.8 parts by weight of lithium nitrate, and 15 parts by weight of the same binder (varnish) as in Example 1 were sequentially blended and mixed to obtain a viscosity of 5.6 cp, a surface tension of 22 dyne/cm, and a specific resistance.
A white ink of 720 Ωcm (all values at 20°C) was obtained. When a printing test was conducted on a steel plate using this ink, good results similar to those in Example 1 were obtained. Further, when the printed matter was heated in air at 800° C. for 30 minutes and then cooled to room temperature, it completely adhered to the steel plate as in Example 1 and had good visibility.
Further, even when the printed matter was heated to 650°C again, there was no disturbance in the printing. Example 4 First, a sol of glass components is prepared. The sol of Example 4 is a solid colorless 35PbO−10Na ₂ O.
-15B ₂ O ₃ -40SiO _2- based composition,
It is made using the following process. Ethyl orthosilicate dissolved in ethanol and aqueous ammonia dissolved in ethanol (ammonia is
(equivalent mole to Si) is heated to reflux for 5 hours in a predetermined container for reflux. On the other hand, lead acetate, isopropyl alcohol, xylene (solvent), and metallic sodium are heated to reflux for 4 hours to prepare lead isopropoxide. Next, inside the container was lead isopropoxide,
Each metal alkoxide of sodium methylate and triethylborate is added together with a predetermined amount of ethanol, and reflux is continued for 2 hours. After that, a mixed solution of water (3 times the mole of the above alkoxide) and ethanol was added, cooled to room temperature, and stirred for 1 hour to form a sol in which solids were dispersed (solid content concentration 10).
%, average particle size 0.1, maximum particle size 0.5 μm). Next, in the same manner as in Example 3, white pigment powder (manufactured by Teikoku Kako KK, fine particle titanium oxide MT-500B) was used.
(average particle diameter of about 35 mμ) 20 parts by weight, pigment dispersant (Polyster A-1060) 0.1 parts by weight, 40 parts by weight of the sol obtained by the above steps of Example 4, 0.8 parts by weight of lithium nitrate
parts by weight, and 15 parts by weight of the same binder (varnish) as in Example 1 were sequentially mixed to obtain a mixture with a viscosity of 4.3 cp, a surface tension of 23 dyne/cm, and a specific resistance of 830 Ωcm (all values at 20°C).
A white ink was obtained. When a printing test was conducted on an aluminum plate using this ink, good results similar to those in Example 1 were obtained. Furthermore, even after baking the printed matter in air at 500° C. for 1 hour, the printed dots were completely fused to the aluminum plate surface and visibility was good. Furthermore, even when the printed matter was heated to 400°C again, there was no disturbance in the printing. Comparative Example 1 100 parts by weight of methyl methacrylate and 12 parts by weight of azobisisobutylnitrile were mixed with 200 parts by weight of ethyl alcohol.
The average molecular weight is
Obtain 45,000 Acrylic Resin Varnish. this varnish
30 parts by weight, 6 parts by weight of yellow dye (Neosapon Yellow GG from BASF), 1.5 parts by weight of lithium nitrate, and silicone oil (Shin-Etsu Chemical KK Manufacturing, KF
-56) Added 2 parts by weight, viscosity 2.1cp, surface tension 20dyne/cm, specific resistance 750Ωcm (all values at 20℃)
An ink was prepared. When a printing test was conducted on a steel plate using this ink, similar good results as in Example 1 were obtained. However, when this printed material is heated to 250℃,
The printed dots became discolored and visibility became very poor, and at the same time, the printing easily disappeared when rubbed with a finger. Comparative Example 2 5 parts by weight of titanium oxide were mixed using ethanol as a solvent, and the mixture was mixed and pulverized in a pot mill for 48 hours. Thereafter, particles with a diameter of 2 μm or more were removed using a filter, and a solvent solution was prepared to obtain a colorant dispersion with a solid content concentration of 20%. For 100 parts by weight of the above colored dispersion,
13 parts by weight of the acrylic resin varnish in Example 1 was added, and 1.5 parts by weight of nitium nitrate and a surfactant (manufactured by Sumitomo 3MKK, fluorine-based surfactant FC) were added.
-430) 0.7 parts by weight was added to obtain an ink with a viscosity of 3.2 cp, a surface tension of 28 dyne/cm, and a specific resistance of 930 Ωcm (all values at 20°C). When a printing test was conducted on a steel plate using this ink, similar good results as in Example 1 were obtained. However, when the printed matter was heated at 250°C for 30 minutes, the adhesion of the printed dots decreased significantly due to the decomposition of the binder, and they easily fell off. (Effects of the Invention) In the first invention, since a colored hydrolyzed solid of a metal alkoxide is blended as a glass component, the hydrolyzed solid itself has the function of a pigment. In the second aspect of the present invention, an ink of a predetermined color is obtained by blending a hydrolyzed solid of a metal alkoxide and a pigment as glass-based components. The hydrolyzed solids blended in both the first and second inventions are produced by the hydrolysis treatment of metal alkoxides, so by adjusting the treatment conditions, the solid particles have an average particle size of 0.6 μm or less, Moreover, it can be made to have a maximum particle diameter of 2 μm or less, and does not cause clogging of ink jet nozzles of inkjet printers. Further, in both the first and second inventions, the ink to be printed on the printing material is attached to the printing material by a binder, and the glass-based component of the adhering ink is fused to the printing material by heat treatment. The glass component is heat resistant, and when heated to a temperature below the melting point of the glass component, the visibility of the printed dots does not deteriorate and the dots do not peel off. That is,
The inks of both of the present inventions do not clog the ink jet nozzle of an inkjet printer, and because they contain a conductivity imparting agent, they satisfy the conductivity conditions.
The print formation is good, and since the glass-based component is blended, the visibility and adhesion of the print can be improved even at high temperatures where colorants and binders discolor and decompose.

Claims (1)

[Scope of Claims] 1. An ink for an inkjet printer containing a glass component having a pigment color, a solvent, a binder, and a conductivity imparting agent, wherein a hydrolyzed solid of a metal alkoxide is blended as the glass component. Heat-resistant ink for inkjet printers. 2 The colored hydrolyzed solids of metal alkoxide have an average particle size of 0.6 μm or less and a maximum particle size of 2 μm.
The heat-resistant ink for an inkjet printer according to claim 1, wherein the fine particles are as follows, and the melting point of the fine particles is within the heat-resistant temperature range of the printing material. 3. An ink for inkjet printers containing a pigment, a pigment dispersant, a solvent for glass-based components, a binder, and a conductivity imparting agent, wherein a hydrolyzed solid of a metal alkoxide is blended as the glass-based component. Heat-resistant ink for inkjet printers. 4. The heat-resistant ink for an inkjet printer according to claim 3, wherein the pigment is fine particles having an average particle size of 0.6 μm or less and a maximum particle size of 2 μm or less. 5 Claims in which the hydrolyzed solid material of metal alkoxide is fine particles with an average particle size of 0.6 μm or less and a maximum particle size of 2 μm or less, and the melting point of the fine particles is within the heat-resistant temperature range of the printing material. The heat-resistant ink for an inkjet printer as described in item 3.