JP3181164B2 - Offset printing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset printing method, and more particularly to an offset printing method for transferring a fine pattern such as a stripe and a mask pattern of a color filter for a color display on a substrate such as glass to 100%.

[0002]

2. Description of the Related Art Conventionally, in printing a stripe and a mask pattern of a color filter for a color display liquid crystal display, a method of receiving ink from a plate to a printing rubber blanket and performing offset printing on a substrate such as glass is adopted. . In this case, a method of partial transfer and a method of 100% transfer are known as a method of transferring ink to a substrate such as glass.

[0003] Of these methods, a 100% transfer method is generally adopted in which the surface rubber of the blanket is made of silicone rubber to improve the releasability from the ink and is used. Then, as a method of ink, a solvent that easily dissolves in the silicone rubber is added to the ink, and the solvent in the ink is dissolved in the silicone rubber to reduce the interfacial tension at the interface between the ink and the silicone rubber, thereby facilitating peeling of the ink from the silicone rubber. And a method of transferring 100% from a silicone rubber blanket onto a substrate such as glass. The solvent type ink in which a solvent is added to such an ink is a very effective method for performing 100% transfer.

However, when printing is performed for a long time, the silicone rubber swells with the solvent, and ink acceptance and transfer gradually deteriorate, and the stripe line becomes a snake antinode shape or linearity deteriorates. Phenomenon occurs. As a result, when incorporated and operated in a liquid crystal display, it causes a decrease in contrast and image quality.

[0005]

As described above, when a solvent type ink is used, 100% of the ink is applied from a silicone rubber blanket, which is the object of this printing, to a base such as glass.
As a means of% transfer, the early stages of printing give good results. However, when printing is performed for a long time, the acceptance of ink from the intaglio to the silicone rubber blanket or the transfer of ink from the silicone rubber blanket to glass or the like becomes poor, and the linearity of the stripe or the stripe becomes a snake antinode. As a result, when incorporated and operated in a liquid crystal display, it causes a decrease in contrast and image quality.

In order to solve this phenomenon, it is necessary not to add a solvent that swells the silicone rubber blanket in the ink, or to add a solvent that does not swell the silicone rubber. However, if such a method is adopted, it is difficult for the ink to transfer 100% from the silicone rubber blanket to a base such as glass.

[0007] The cause of this is that the solvent in the ink is transferred to the silicone rubber at the interface between the silicone rubber and the ink, the surface tension of the silicone rubber is reduced, and the ink is transferred 100%. Without solvent or
When a solvent that does not swell the silicone rubber is added, there is no change in interfacial tension at the interface between the silicone rubber and the ink.
That is, 100% transfer of the ink becomes impossible. In the case of the solventless ink, the cohesive force of the ink is stronger than the interfacial tension between the silicone rubber and the ink, so that the reception of the silicone rubber blanket from the intaglio becomes very poor.

The present invention has been made in view of such circumstances, and accepts ink from the intaglio plate to the silicone rubber blanket by adding a solvent free or a solvent that does not easily swell the silicone rubber, which can cope with long-time printing. And an offset printing method capable of performing 100% transfer printing of ink from a silicone rubber blanket to a substrate such as glass.

[0009]

SUMMARY OF THE INVENTION The present invention, in the offset printing method for printing an ink on infrastructure such as glass through a silicone rubber blanket from the plate, the cohesive force of the ink when receiving the ink to a rubber blanket from the plate
Is smaller than the interfacial tension between silicone rubber and ink.
When the ink temperature is increased and the ink is transferred from the rubber blanket to the base, the cohesive force of the ink is
Ink temperature so that it is higher than the interfacial tension between
This is an offset printing method characterized by lowering .

In order to perform 100% transfer printing of ink without a solvent or by adding a solvent which is hardly soluble in silicone rubber, first, the cohesive force of the ink is changed to the silicone rubber in the process of receiving the ink from the intaglio to the silicone rubber blanket. If it is not less than the interfacial tension of the ink, the ink will not be accepted by the silicone rubber blanket. Therefore,
Considering the temperature characteristics of the ink, the cohesive force of the ink is reduced by making use of the fact that the ink viscosity decreases when the temperature of the ink becomes high, thereby making it necessary and sufficient to receive the ink 3 from the intaglio 1 to the silicone rubber blanket 2. (See FIG. 1). FIG. 1 shows a case where the cohesive force of the ink 3 is larger than the interfacial tension between the silicone rubber and the ink 3.
If the interfacial tension is smaller than the above, the result is as shown in FIG. Reference numeral 4 in FIG. 2 indicates a glass substrate.

Next step silicone rubber blanket 2
The ink 3 received by the glass substrate (glass plate 5)
If the cohesive force of the ink 3 is larger than the interfacial tension between the silicone rubber and the ink 3 in the step of transferring the ink 3 to 100%, the ink 3 changes to 100% (see FIG. 4). When the tension is smaller than the interfacial tension between the rubber and the ink 3, it is broken in the middle of the ink 3 and becomes a destructive transition (see FIG. 3). Reference numeral 5 in the figure is a glass plate.

Therefore, by lowering the ink temperature in the ink transfer step as opposed to the ink receiving step, the cohesive force of the ink becomes larger than the interfacial tension between the silicone rubber and the ink, resulting in 100% transfer. Since no solvent is added, there is no swelling of the silicone rubber, and a printed matter which is not different from the initial printed matter even when printed for a long time is obtained.

In addition, since the ink 3 can be transferred to the glass plate 5 by increasing the viscosity of the ink to a very high level, the bleeding of stripes and whiskers due to stringing are eliminated, and the stripes are printed with a solvent type ink (FIG. 5). (See FIG. 6) approaches the ideal shape required for the color filter (see FIG. 6), and high-quality stripes can be printed. Also, when performing overprinting, since the ink viscosity of the previously printed stripe is high, the shape does not have to be deformed, and this is a very good printing method for printing color filters. Thus, in the receiving step, the ink temperature is set higher than room temperature, the cohesive force of the ink is made smaller than the interfacial tension between the ink and the silicone rubber blanket, and the ink temperature is set in the step of allowing the silicone rubber blanket to receive the ink, and in the transfer step. and less than the cohesive strength of an interfacial tension of the ink at room temperature or lower than room temperature inks and the silicone rubber blanket, a method of printing with a temperature difference of the ink in the step of transferring the base of glass or the like of the ink, following the ink temperature This is called the difference printing method. In this case, if the temperature of the silicone rubber blanket is set to room temperature or lower than room temperature depending on the temperature characteristics of the ink, the ink reception and transfer are improved.

As described above, if the stripe printing is performed by the ink temperature difference printing method, 100% of the ink can be obtained with the solventless ink.
Transfer is achieved, and the swelling of the silicone rubber in the solvent is eliminated, and the quality of the initial printed matter and the quality of the printed matter after long-time printing are maintained. In addition, since high-viscosity ink can be transferred to a substrate such as glass, bleeding of stripes and beards due to stringing are eliminated, and the stripe shape is very close to the ideal shape (see Fig. 6), creating a high quality color filter. As a result, when incorporated and operated in a liquid crystal display, very good contrast and image quality can be obtained.

[0015]

According to the ink temperature difference printing method of the present invention, in the ink receiving step, the ink temperature is raised to a high temperature (the cohesive force of the ink <
(Interfacial tension between silicone rubber and ink), improve ink acceptance. In the subsequent transfer step, 100% transfer can be facilitated even with a solventless ink by lowering the ink temperature (cohesive force of ink> interfacial tension between silicone rubber and ink).

[0016]

Embodiments of the present invention will be described below. (Example 1) A rubber blanket for printing has a hardness of chloroprene sponge rubber of 40 ° (Asker C
Mold), thickness 1.0mm, middle stabilizer 12
0.18 mm of a polyester film as the adhesive, and silicone rubber (trade name: TSE346) as the surface rubber 13
6, manufactured by Toshiba Silicone Co., Ltd.) (see FIG. 7). In order to make the surface a mirror surface, the iron plate is chromium-plated and brought into close contact with the chrome-plated iron plate before the silicone rubber is cured to obtain a printing rubber blanket having a surface condition of less than 0.5 μm (Rz). Was.

The ink comprises a pigment, a vehicle, a surfactant,
A solventless ink having the temperature characteristics shown in FIG. 8B was prepared using a gelling agent and wax. In FIG. 8, the B ink may have a small temperature difference between acceptance and transfer (wax ink). Also, the C ink does not achieve 100% transfer unless the temperature difference between acceptance and transfer is increased (it is not ideal as a 100% transfer ink). In addition, A ink is B ink and C ink.
It can be said that it is an intermediate of ink (higher viscosity with the amount of pigment blended).

The printing test was performed using a flat-bed component machine, and the printing process was performed in the following manner. (1). Keep the ink at 60 ° C. (2). Keep the intaglio at 60 ° C.

(3) The ink of (1) is filled in the intaglio of (2), and excess ink is scraped off with a doctor knife. (4) Receive the ink from the intaglio into a silicone rubber blanket at 60 ° C.

(5) The glass plate to be printed is kept at about 15 to 20 ° C. (6) A silicone rubber blanket receiving the ink of (4) above was applied to the glass plate of (5) with a printing pressure of 0.4 mm to transfer the ink to the glass plate by 100%. (7) The glass plate printed in (6) was placed in a 200 ° C. oven for 30 minutes to cure the printed stripe.

Here, the intaglio has a line width of 50 μm and a depth of 10 μm.
m stripes were used. As a result of printing under the above conditions, 100% of the ink was transferred even with the solventless ink, and the stripe shape was printed close to the ideal shape (see FIG. 6). When this was incorporated into a liquid crystal display and operated, very good contrast and image quality could be obtained. Similarly, set the ink temperature and the intaglio temperature at room temperature of 24 ° C.
When a printing test was conducted, only a small amount of the ink was accepted by the silicone rubber blanket, and the next ink transfer step could not be performed.

Example 2 The silicone rubber blanket used in Example 1 was used. Fig. 8
By removing the wax of the B ink and controlling the blending amount of the pigment, a solventless ink having the temperature characteristics of the A ink of FIG. 8 was prepared. The printing test was performed using the same machine as in Example 1, and the printing process was performed by the following method.

(1). Keep the ink at 60 ° C. (2). Keep the intaglio at 60 ° C. (3) Fill the intaglio plate of (2) with the ink of (1) above and scrape off excess ink with a doctor knife.

(4) Receiving the ink from the intaglio plate at 60 ° C. on a silicone rubber blanket. (5) The glass plate to be printed is cooled to about 5 to 10 ° C. (6) A silicone rubber blanket receiving the ink of (4) above was applied to the glass plate of (5) under a printing pressure of 0.4 mm to transfer the ink to the glass plate by 100%.

(7) The glass plate printed in (6) above is
The printed stripes were cured by placing them in a 0 ° C. oven for 30 minutes. Here, the intaglio used was 50 μm in line width and 10 μm in depth.
Of stripes were used. As a result of printing under the above conditions,
Even with the solventless ink, 100% of the ink was transferred, and the stripe shape was printed close to the ideal shape (FIG. 6). When this was incorporated into a liquid crystal display and operated, very good contrast and image quality could be obtained.
Similarly, when a printing test was conducted at an ink temperature and an intaglio temperature of 24 ° C. at room temperature, only a small amount of the ink was accepted by the silicone rubber blanket, and the next ink transfer step could not be performed.

Example 3 The silicone rubber blanket used in Example 1 was used. As the ink, a solventless ink having the temperature characteristics of the C ink was prepared by reducing the amount of the pigment of the A ink in FIG. 8. The printing test was performed using the same component machine as in Example 1, and the printing process was performed by the following method.

(1). Keep the ink at 60 ° C. (2). Keep the intaglio at 60 ° C. (3) Fill the intaglio plate of (2) with the ink of (1) above and scrape off excess ink with a doctor knife.

(4) Receive the ink from the intaglio into a silicone rubber blanket at 60 ° C. (5). The glass plate to be printed is cooled to about 0 ° C. (6) A silicone rubber blanket receiving the ink of (4) above was applied to the glass plate of (5) under a printing pressure of 0.4 mm to transfer the ink to the glass plate by 100%.

(7) The glass plate printed in (6) above is
The printed stripes were cured by placing them in a 0 ° C. oven for 30 minutes. Here, the intaglio used was a stripe having a line width of 50 μm and a depth of 10 μm.

As a result of printing under the above conditions, 100% of the ink was transferred even with the solventless ink, and the stripe shape was printed close to the ideal shape (FIG. 6). When this was incorporated into a liquid crystal display and operated, very good contrast and image quality could be obtained. Similarly, when a printing test was conducted at an ink temperature and an intaglio temperature of 24 ° C. at room temperature, only a small amount of the ink was accepted by the silicone rubber blanket, and the next ink transfer step could not be performed.

[0031]

As described in detail above, according to the present invention,
Solvent-free by giving ink temperature difference between the process of receiving ink from the intaglio to the silicone rubber blanket in the intaglio offset 100% transfer printing and the process of transferring the ink from the silicone rubber blanket that received the ink to the base such as glass Use 10 inks on a base such as glass.
0% can be transferred. This is because by increasing the ink temperature in the ink receiving step, the cohesive force of the ink can be made smaller than the interfacial tension between the silicone rubber and the ink, and the necessary and sufficient ink can be received on the silicone rubber blanket.

Further, since the ink temperature is raised in the ink receiving step, a high viscosity ink can be used, and the quality of the printed stripe can be improved. Specifically, the linearity of the stripe is improved, and the whiskers and bubbles of the stripe are eliminated. Further, in the ink transfer step, the ink is transferred at a low temperature, so that the viscosity of the ink increases,
The cohesive force of the ink becomes larger than the interfacial tension between the silicone rubber and the ink, so that 100% transfer is easily performed.

Since the ink is transferred to the glass in a high-viscosity or waxy state, the stripe shape becomes a stripe shape close to the ideal shape (FIG. 6), and the height of the stripe becomes stable. As described above, the stripe printed by the ink temperature difference printing method has much higher quality than the stripe printed by the solvent type ink, and when the color filter is incorporated in a liquid crystal display and operated, a good contrast and a high contrast can be obtained. The disadvantages of the conventional method that can obtain high quality image (specifically, poor printing durability, poor stripe quality, and narrow selection range of ink) can be solved by using the printing method of the ink temperature difference printing method. I was able to overcome it.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an ink receiving process from an intaglio to a silicone blanket.

FIG. 2 is an explanatory view of an ink transfer step from a glass substrate to a silicone blanket.

FIG. 3 is an explanatory view of destructive transfer in an ink transfer step from a glass substrate to a silicone blanket.

FIG. 4 is an explanatory diagram of 100% transfer in an ink transfer step from a glass substrate to a silicone blanket.

FIG. 5 is an explanatory diagram of a cross-sectional shape of a stripe printed with a solvent-type ink.

FIG. 6 is an explanatory diagram of a cross-sectional shape of an ideal stripe.

FIG. 7 is a cross-sectional view of a silicone rubber blanket used for printing.

FIG. 8 is a characteristic diagram showing a relationship between ink viscosity and ink temperature in various inks.

[Explanation of symbols]

1 ... intaglio, 2 ... silicone rubber blanket,
3 ... ink, 4 ... glass base, 11 ... compression layer,
12 ... stabilizer, 13 ... silicone rubber.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B41M 1/00-7/02 B41F 1/00-35/06

Claims (1)

(57) [Claims] In an offset printing method for printing ink on a substrate such as glass through a silicone rubber blanket from a plate, when ink is received from the plate onto a rubber blanket, the cohesive force of the ink is reduced by the silicone rubber and the ink.
Ink when to be less than the interfacial tension raised ink temperature, to transfer ink to the foundation from the blanket
Is larger than the interfacial tension between silicone rubber and ink
An offset printing method characterized by lowering the ink temperature so as to reduce the temperature .