JPH02277687A - Method and device for forming ink thin film for image formation - Google Patents

Abstract

PURPOSE:To uniformly make an ink layer thin by supplying a definite amount of ink by supply ink changing in its adhesiveness corresponding to the polarity of applied voltage to the conductive groove formed to a roll and subsequently forming said ink into a membrane by a separate roll. CONSTITUTION:Ink 1 changing in its adhesiveness corresponding to the polarity of applied voltage is introduced in the groove 9 of a thin layer forming roll 9 under pressure by an ink coating roll 2. The groove 9 is positioned between the insulating layers 8 applied to a part of the surface of the thin layer forming roller 3. The conductive surface corresponding to the bottom surface of the groove part of the thin layer forming roll 3 is composed of a conductive material. The ink in the groove 9 is subsequently is transferred to an ink support roll 5 by voltage 7 while the excessive ink on the surfaces of the insulating layers 8 is removed by a blade 4 provided if necessary and the transferred ink is smoothed by a pressure roll 6 and the ink on the surface of the pressure roll 6 forms a membrane layer having a definite thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for forming a thin ink film for image formation in an image recording method using ink whose adhesion changes with the application of voltage.

[Conventional technology]

In order to record an image, a method is known in which a thin film of ink is brought into contact with a chain plate to form an ink image in accordance with the image pattern, as a means of placing ink on a plate on which an image pattern has been formed. However, such thinning of ink is a process widely performed in painting, printing, etc., and the following methods are known. That is, painting 2. 2. Description of the Related Art A method is known in which a large number of rollers arranged in series are used to apply a thin film such as putty or ink in printing or the like.

[Problem to be solved by the invention]

With the method of arranging many rollers, it is difficult to control the amount of ink applied because the ink is sheared by both the adherent and the adhered object, and when the viscosity exceeds several tens (10) poise, the ink surface becomes wavy. This results in an increase in the number of steps, and it is difficult to control the amount of coating.

In particular, the ink used in the present invention is an image recording ink whose adhesion changes depending on the polarity of the applied voltage and is basically composed of inorganic or organic fine particles and a liquid dispersion medium, and the viscosity of this ink is usually , measurement angular frequency 0.1rad
/s of 10' poise or more, which is about two orders of magnitude higher than that of ordinary lithographic printing inks, requiring a large amount of torque to form a thin film, and the conventional method described above could not successfully form a thin film.

In addition, the viscosity of the ink changes depending on the temperature and exhibits thixotropy, and the viscosity of the ink changes depending on the sliding speed (rotational speed of the roll), making it more difficult to form a constant amount of ink film on the roll. Ta.

The present invention has been made in view of the above-mentioned problems, and provides an excellent method and apparatus for forming an ink thin film.

[Means to solve the problem]

According to the present invention, in a method for forming an ink thin film for image formation on a roll in an image recording method using an ink whose adhesion changes depending on the polarity of an applied voltage, the grooves of a roll having conductive grooves are , and then transfer the ink onto the conductive roll by applying a voltage between another conductive roll and the groove, and then transfer the ink on the conductive roll with another roll. By making the film thinner,
It becomes possible to efficiently form a uniform thin ink film M, and as a result, printed images obtained by the above method are sharp and free from color unevenness.

According to the present invention, an apparatus for carrying out the above method is provided with a series of rolls consisting of at least a thinning roll, an ink carrying roll, and a pressure roll, and the thinning roll receiving ink is provided with a roll surface. It has a conductive groove, the groove is electrically connected to the conductive roll surface of the ink carrying roll via the ink, and the pressure roll presses the ink on the ink carrying roll to form a thin film. The above method can be suitably carried out in a short time and with a small number of steps using an ink thin film forming apparatus for image formation equipped with the series of rolls.

That is, in the ink thin film forming method of the present invention, ink is supplied to a groove on a roll having a certain depth, and the ink in this groove can be transferred onto the next roll by applying a voltage without applying shearing force. A fixed amount of ink can be supplied onto the roll in a short time.

In the present invention, a roll having conductive grooves (thinning roll) is one in which grooves of a certain depth and size are provided on the roll surface of the roll, and at least the bottom surface of the groove and the side surface thereof. is made of conductive material. The shape and arrangement of the grooves are not particularly limited; grooves may be provided in stripes with a desired width in the rotational direction of the roll, stripes with a desired width in the axial direction of the roll, or grids. Any shape that can accommodate a predetermined amount of ink in the groove may be used, such as a dot-shaped or dot-shaped groove, but the efficiency of supplying ink into the groove, another roll (ink carrying roll)
Uniformity in stably moving the ink in the groove, ease and uniformity in thinning the ink that has moved onto the roll in the groove on another roll (pressure roll), and further roll processing. From the viewpoint of ease of use, it is preferable to use striped grooves in the direction of rotation of the roll.

Furthermore, the fact that at least the bottom surface of the groove is conductive means that the side surfaces of the groove may be similarly conductive, and in this case, the entire surface constituting the groove is conductive. Since ink is not normally accommodated in the portions of the roll other than the grooves, they are not directly involved in the movement of ink and do not need to be electrically conductive. However, this does not mean that ink cannot be stored in areas other than the grooves, but rather that ink can be efficiently and stably transported if it is mainly stored in the grooves. If the part other than the groove is an insulator, and the part is kept in contact with the next roll (ink carrying roll) so as not to contain ink, and the groove part and the ink carrying roll are electrically insulated, the groove Since the ink inside the roller can be secured and the rolls can be kept in contact with each other, the flow of ink can be easily made constant.

As a method for supplying ink into the grooves of the roll having the grooves (hereinafter referred to as a thinning roll), a normal ink supply means can be used. In other words, a roll generally referred to as an ink coating roll and a thinning roll can be used. This can be carried out by a method such as supplying ink between the thinning roll and the grooves on the thinning roll.

Next, the ink in the groove moves onto another roll, an ink carrying roll, and the roll surface of the ink carrying roll is a conductor and is electrically connected to the groove through the ink. That is, the bottom surface of the groove, which is the conductive part, and the roll surface of the ink carrying roll are used as a pair of electrodes, and a voltage can be applied to the ink existing between them. Even if the parts of the thinning roll other than the grooves are in contact with the ink carrying roll surface, if the parts other than the grooves are insulating, the thinning roll and the ink carrying roll will not come into electrical contact. A voltage will be applied to the ink within the groove. The adhesion of the ink to which a voltage is applied changes, and depending on the type of ink, it will adhere to the cathode side or the anode side.If the polarity of the applied voltage is set according to the purpose, the ink in the groove will stick to the cathode side or the anode side. It will be moved onto the carrier roll. In this case, even if the side surfaces constituting the groove are insulators, the influence of the side surfaces is small because the bottom surface is significantly large in area. The gap between the thinning roll and the ink carrying roll may be appropriately set depending on the viscosity of the ink, the rotational speed of the roll, etc. The rolls may be brought into contact with each other as long as the portion other than the groove is an insulator.

According to the above method, the ink moves from the thinning roll onto the ink carrying roll with almost no shearing force, so a constant amount is efficiently and uniformly moved without being affected by the viscosity of the ink. can be done. Furthermore, since the amount of movement can be made relatively large, the movement can be carried out in a short time.

Next, the ink transferred onto the ink carrying roll is made into a thin film by another roll, that is, a pressure roll. Since the amount of ink supplied from the ink carrying roll is constant, it is easy to form a thin film and a uniform thin film can be obtained.

As described above, the thin film forming method of the present invention is capable of forming a thin ink film on a roll while controlling the coating amount in a short time and in a small number of steps, and will be further explained below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a thin film forming apparatus according to the ink thin film forming method of the present invention, and FIG. 2 is a schematic oblique view. The ink (1) is coated on an ink coating roll (2
) into the groove (9) of the thinning roll (3).

This groove (9) is located in FIG. 3 between a part of the surface of the thinning roll (3) covered with an insulating layer (8). The conductive surface corresponding to the bottom of the groove of the thinning roll (3) is aluminum.

The roll may be made of a conductive material such as copper, stainless platinum, gold, or chromium, and the roll itself may be made of such material or may be coated with such material. It is preferable if the roll itself is electrically conductive because current can be applied directly to it. Natural and/or synthetic polymers can be used as the material for the insulating layer (8). The depth and width of the groove (8) can be determined depending on the desired thickness of the ink layer, and the depth of the groove (8) is usually 0.001 to 1.
00 mm, and the width is preferably 0.001-100 mm. The width of the insulating layer is preferably 0.001N100mm.

The insulating layer (8) can be formed on the conductive thin film roll (3) by applying ultraviolet curable resin or thermosetting resin onto the roll and then irradiating it with ultraviolet rays, or by heating it. I can do it. Alternatively, it can also be formed by applying a solution containing a polymer and then evaporating the solvent. Alternatively, it can be formed by using a heat-shrinkable polymer tube, inserting a roll into the tube, and heat-shrinking the tube.

The roll diameter of the thinning roll is usually about 1 to 1000 mm, and the peripheral speed of rotation can be about 0.001 to 1000 cm/s.

The ink filled in the grooves (8) is then removed from the surface of the insulating layer (8) by a blade (4) provided as necessary, and then transferred to the ink carrying roll (5) by a voltage (7). Ru. In Figures 1 and 2,
The ink shows non-adherence to the cathode and adhesion to the anode when voltage is applied.

The ink transferred to the ink carrying roll (5) is smoothed by the pressure roll (6), and the ink on the surface of the pressure roll (6) forms a thin film layer with a constant thickness.

The voltage applied to move the ink from the layer thinning roll to the ink carrying roll may normally be about 3 to 100 V in direct current.

According to the present invention, the thickness of the ink thin film layer formed on the pressure roll can generally be about 0.001 to 50 mm.

Next, the ink according to the present invention will be explained.

The ink that can be used in the present invention may be a known ink that basically consists of inorganic or organic fine particles and a liquid dispersion medium.

Image forming methods can be divided into the following two types depending on the properties of the ink used.

(1) When the adhesion changes due to Coulomb force due to voltage application, the basic composition of the ink consists of inorganic or organic fine particles and a liquid dispersion medium, and the difference in the chargeability of the fine particles is used. It is something.

In this case, if the ink is prepared to have adhesive properties from the beginning and contains fine particles that are easily charged negatively, the ink will not adhere to the negative electrode side when a voltage is applied.
On the other hand, if particles that are easily positively charged are included, the ink will not adhere to the positive electrode side when a voltage is applied.

In addition, if the ink is prepared so that it does not have adhesive properties from the beginning and contains particles that are easily charged negatively,
When a voltage is applied, ink will adhere to the positive electrode side, and on the other hand, if particles that are easily charged positively are included, ink will adhere to the negative electrode side when a voltage is applied.

(2) When electricity is applied by applying a voltage, the ink electrolyzes and generates gas, resulting in a change in adhesion.

In this case, the ink is prepared to have adhesive properties from the beginning, and when a voltage is applied, the ink generates gas near one of the electrodes, and this gas prevents the ink from adhering to the electrode. In order to generate gas through electrolysis, the ink contains a solvent such as water, alcohol, or glycol, or a solvent in which an electrolyte such as sodium chloride or potassium chloride is dissolved. The lower the electrical resistance of the ink, the better; if the volume resistivity exceeds 1O''Ωcm, the amount of current flowing will decrease, or a high voltage will be required to prevent the amount of current flowing, which is undesirable.

When the change in ink adhesion is caused by Coulomb force, easily charged fine particles are used, and charged particles are generated by crosstalk in a liquid dispersion medium described below, for example, in a homogenizer, colloid mill, or ultrasonic disperser. As particles to which a positive charge is imparted, metal particles such as Au, Ag, and Cu, sulfide particles such as zinc sulfide (ZnS), silicic acid particles such as orthosilicic acid (H4Si04), polyamide resin, etc. can be used. can. Further, as the particles to which a negative charge is imparted, iron hydroxide particles, aluminum hydroxide particles, fluorinated mica particles, polyethylene particles, montmorillonite particles, fluororesin particles, etc. can be used. Furthermore, polymer particles containing various charge control agents used as toners for electrophotography can also be used.

As the liquid dispersion medium used in the ink, water, alcohols such as methyl alcohol, glycols such as glycerin can be used alone, or a mixed solvent of two or more of these liquids can be used. The liquid dispersion medium is contained in an amount of 40 to 95 parts by weight, preferably 60 to 85 parts by weight, per 100 parts by weight of the ink.

If the change in ink adhesion is due to the generation of gas due to electrolysis, the liquid dispersion medium may be water, alcohols such as methanol, glycols such as glycerin, or a solvent in which an electrolyte such as sodium chloride or potassium chloride is dissolved. preferable. The contents of the liquid dispersion medium and fine particles are the same as those described above.

In the case of ink that generates gas through electrolysis, the fine particles contained in the ink include silica, fluorocarbon compounds, titanium oxide, carbon black, etc. in addition to those listed above. Considering the viscoelasticity of the ink, it is preferable that the fine particles be swellable fine particles that can retain the above-mentioned liquid dispersion medium in the particles.Such swellable fine particles include:
For example, fluoride mica, synthetic mica such as Na-montmorillonite, Ca-montmorillonite, 3-octahedral synthetic smectite, Na-hectolite, Li-hectolite, Na-teniolite, Na-tetrasilicic mica, Li-teniolite, Silica etc.

Further, the ink may contain colorants such as carbon black and other dyes and pigments that are generally used in the printing and recording fields, as required.

When the ink contains a colorant, the content of the colorant is 0.1 to 40 parts by weight, preferably 1 to 20 parts by weight, per 100 parts by weight of the ink. It may contain a color-forming compound that develops color upon application of voltage. In addition, the ink may contain an electrolyte, thickener, thinner, surfactant, etc. that impart conductivity. Further, it is also possible to make the above-mentioned fine particles themselves function as a coloring material.

The ink thinned by the method of the present invention described above can be used to print an image by moving the ink onto a plate by applying a voltage and then transferring the ink to paper or the like.

〔Example] Hereinafter, the present invention will be explained according to examples.

20 parts of Kazanmei Yuglycerin, 10 parts of water, carbon black (pigment) (manufactured by Cabot, USA, "Sterling 5RJ") 4.
The 5th part was combined for 4 hours using an attritor. To this mixture, 20 parts of colloidal hydrated silicate (manufactured by Kunimine Industries, trade name Sumecton 5A) was added, and the mixture was mixed in a kneader for 2 hours.
Created ink.

The surface of the ink coating roll (2) was coated with Teflon to prevent ink from adhering.

As the thinning roll (3), a platinum-plated stainless steel cylindrical roll with a diameter of 30 mm and a thickness of 50 μm was used.
After heat-shrinking the Teflon heat-shrinkable tube onto this roll and fixing it on the thinning roll, remove unnecessary Teflon coating with a width of 5 mm and a spacing of 5 mm.
A Teflon coating of mm thick was formed on a platinum-plated stainless steel cylindrical roll.

Ink was transferred by the method shown in FIG. 1 using the ink coating roll (2) and the layer thinning roll (3) described above. As the ink carrying roll (5), a platinum-plated stainless steel cylindrical roll with a diameter of 30 mm was used.

While the thinning roll (3), the ink carrying roll (5), and the pressure roll (6) each have a diameter of 30 mm and the thinning roll (3) rotates once at a circumferential speed of 5 mm/sec,
Apply a voltage of 20V from the DC power source (7) to the thin layer roll (3)
and the ink carrying roll (5), and the ink in the grooves of the thinning roll was transferred to the ink carrying roll (5). At this time, the layer thinning roll was used as a cathode, and the ink carrying roll was used as an anode. Ink carrying roll (5) and pressure roll (6)
The ink thin film layer transferred onto the pressure roll (6) had a thickness of 25 parts and was uniformly coated onto the pressure roll (6) at a thickness of 5 μm.

Fukodan 37 parts glycerin, 18 parts water, 8 parts carbon black,
The ink was made into a thin layer in the same manner as in Example 1, except that Senmolinite 3F part (manufactured by Kunimine Industries, trade name: Kunivia F) was used. The thickness of the ink on the pressure roller is 25 parts and 7 μm.
The ink was evenly applied onto the pressure roller.

[Effects of the Invention] As explained above, by using the method and device for thinning ink onto a roll of the present invention, a certain amount of ink can be supplied onto the roll in a short time and with a small number of steps, and the ink can be thinned. The layer can be uniformly thinned, and the printed matter can be sharp and have no color unevenness.

Further, the method of the present invention can be widely applied to the transfer of ink whose adhesion changes with the application of voltage.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of a thin film forming apparatus according to the ink thin film forming method of the present invention, FIG. 2 is a schematic oblique view of the same apparatus, and FIG. 3 is a schematic cross-sectional view showing the configuration of a thin layer roll according to the present invention. FIG. 16 Ink 2, Ink coating roll 3, Thinning roll 4, Blade 5, Ink carrying roll 6, Pressure roll 7, Power supply 8, Insulating layer 9, Groove Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. In a method for forming an ink film on a roll for image formation in an image recording method using an ink whose adhesion changes depending on the polarity of an applied voltage, a roll having conductive grooves is used. The ink is supplied into the groove, and then a voltage is applied between another conductive roll and the groove to transfer the ink onto the conductive roll, and then another roll is applied to transfer the ink onto the conductive roll. A method for forming an ink thin film for image formation, which is characterized by forming an ink into a thin film. 2. In an apparatus for forming a thin ink film on a roll for image formation in an image recording process performed using ink whose adhesion changes depending on the polarity of applied voltage, at least a thinning roll, an ink carrying roll, and a pressurizing roll are used. The thinning roll, which is provided with a series of rolls and is supplied with ink, has conductive grooves on the roll surface, and the grooves are electrically connected to the conductive roll surface of the ink-carrying roll through the ink. An ink thin film forming apparatus for image formation, characterized in that the series of rolls are connected to each other, and the pressure roll presses the ink on the ink carrying roll to form a thin film.