JPH09295468A - Blanket for offset printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blanket for printing in which acceptance transition characteristics are not changed with time and a pattern shape is not disarranged and furthermore a printing error for positional precision in a printing area for a form plate in a pattern area is eliminated. SOLUTION: The blanket for offset printing is constituted of an acceptance transition layer 1 made of a silicone rubber or silicone resin, a base fabric layer 21 provided under it and the lower rubber layer 3 to which various compounding agents are added. A shielding film 4 is provided between the acceptance transition layer 1 and the base fabric layer 21 provided just under it. As the result of providing the shielding film between the base fabric layer 21 and the acceptance transition layer 1, acceptance transition characteristics are not changed with time and a pattern shape is not disarranged. Furthermore, a printing error for positional precision in a printing area for a form plate in a pattern area is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset printing blanket, and more particularly to an offset printing blanket mainly used for various circuit patterns on a glass substrate and precision printing used for LCD color filter printing.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a blanket for offset printing of this type has a receiving transfer layer 1 made of silicone rubber or silicone resin which basically transfers an ink and a strength provided under the receiving transfer layer 1. And a base fabric layer 2 for maintaining the compressibility, and a sponge layer 3 and a base fabric layer for maintaining the compressibility of the blanket under the structure.

[0003]

In the printing blanket as described above,

(1) The surface tension of the acceptance transfer layer changes with time (acceptance and transfer characteristics change), (2) the pattern shape is disturbed (pixel deformation), and (3) pattern area plate. However, there are drawbacks such as the occurrence of a printing error in the positional accuracy of the printing area with respect to.

The present invention has been made in view of the above points, and the acceptance transfer characteristic does not change with time, the pattern shape is not disturbed, and further, the printing error of the positional accuracy of the printing area with respect to the plate of the pattern area. The purpose is to provide a blanket for printing.

[0006]

In order to solve the above problems, the offset printing blanket according to the present invention comprises:
In an offset printing blanket having a silicone rubber or silicone resin receiving transfer layer, a base fabric layer provided thereunder, and a lower rubber layer to which various compounding agents are added, the receiving transfer layer and the base fabric immediately below it. It is characterized in that a shielding film is provided between the layers.

According to the present invention, as a result of providing the shielding film between the base cloth layer and the receiving and transferring layer, the receiving and transferring characteristics do not change with time, the pattern shape is not disturbed, and further printing on the plate in the pattern area is carried out. It is possible to provide a printing blanket with no printing error due to the positional accuracy of aria.

The present invention will be described in more detail.

As a result of researching the above-mentioned conventional printing blanket, the present inventor has found that the disadvantage of the above (1) is a compounding agent, especially a vulcanization accelerator, which is compounded in a lower synthetic rubber layer such as a sponge layer. The anti-aging agent blooms, impairing the releasability that silicone rubber or silicone resin originally has, or the platinum catalyst is added to cause a reaction due to the ultraviolet rays of fluorescent lamps, and the acceptance transfer of the surface It was found that the surface-acceptance transition layer was changed by yellowing the layer.

Further, the drawback (2), that is, the disorder of the pixel shape, is caused by the base cloth layer immediately below the acceptance transition layer (a cotton cloth is mainly used).
It was found that the waviness causes a microscopic change in the compressive stress during printing, causing a partial change in the printed film thickness, which causes uneven color in the color filter and changes in the conductive characteristics in the electrode. It was

Further, the above-mentioned (3), that is, the error of the positional accuracy of the pattern area is similarly caused by the elongation of the base cloth (vertical, horizontal).
It has been found that the cause is that the print area expands due to. In the past, it may reach ± 60 μm, and the current situation is that it does not reach the target ± 10 μm.

In the present invention, as shown in FIG. 1, a transfer layer 1 made of a silicone rubber or a silicone resin which basically transfers the ink and a base cloth layer provided under the transfer layer 1 for maintaining the strength. 2 and further has a sponge layer 3 and a base fabric layer 2 for maintaining the compressibility of the blanket in the lower part. As a result of the above consideration, the structure is such that the shielding film 4 is provided between the acceptance transfer layer 1 and the base fabric layer 21 immediately thereunder. The shielding film 4 is adhered to the sponge layer 3 described above via the adhesive layer 5 (the adhesive layer 5 and the sponge layer 3 correspond to the lower rubber layer).

As a material for such a lower rubber layer, N is used.
A conventional lower rubber layer such as BR can be effectively used.

The shielding film layer 4 is for shielding blooms such as vulcanization accelerators and antioxidants from the lower rubber layer to which the compounding agent has been added as described above, and also the base fabric 21 immediately below. By suppressing the stretching and waviness, the pixel shape is disturbed and the positional accuracy error of the pattern area is eliminated.

Such a shielding film can be basically used as long as it can shield the compounding agent of the lower rubber layer, but it makes uniform the compressive stress (prevents pixel deformation) and improves the positional accuracy of the pattern area. Therefore, compression elasticity and extension elasticity are major factors.

That is, the compressive elasticity of the base cloth 2 immediately below
If it is larger than 1, the stress distribution can be made uniform, and basically, the deformation of pixels can be prevented. As such compression elasticity, the compression elasticity of the base cloth is generally 0.01 to 0.05.
Since it is kgf · mm ^-2 , 0.05 to 0.20k
It should be gf · mm ⁻² . 0.05kgf ・ mm ^-2
If it is less than 0.2 mm, the compression stress may not be uniformed. On the other hand, if it exceeds 0.20 kgf · mm ⁻² , the rigidity against bending becomes high and it becomes difficult to mount it on the printing cylinder.

The elongation property is an important parameter for improving the positional accuracy of the pattern area, and basically the base cloth 21
It is sufficient if the elastic modulus is higher than that. In particular, 0.2-
It is desirable that the 0.8% modulus is 100 to 500 kgf · m ⁻¹ . If it is less than 100 kgf · m ⁻¹ , there is a risk that the positional accuracy will not be sufficiently improved, while 500 kgf
・ If it exceeds m ^-1 , rigidity against bending becomes high, and it becomes difficult to mount it on the printing cylinder.

The thickness of the shielding film is 100 to 150 μm
It is good. If it is less than 100 μm, the waviness of the base cloth cannot be covered, and if it exceeds 150 μm, the bending rigidity becomes strong, which may cause difficulty in mounting on a printing machine.

Examples of the shielding film as described above include polyester films, synthetic resin films such as PEN, PPS, and polyimide, as well as stainless steel, aluminum,
A metal film such as copper can be used.

Examples of the present invention will be described below.

[0021]

[Example] Silicone rubber was used as the acceptance transfer layer 1, and a polyester film having a thickness of 125 μm (made by Toray; mirror name S56) was formed directly under the silicone rubber. At this time, a sponge layer of NBR is used, and an alkoxysilane-based primer is used as an adhesive between the acceptance transfer layer and the shielding film.
An NBR adhesive was used as the adhesive.

The above-mentioned shielding film exhibits stress (compressive elasticity) against compressive strain and stress (expandable elasticity) against tensile strain as shown in FIGS. In the figure, A,
B and C indicate a polyester film, a cotton cloth 1 and a cotton cloth 2, respectively. As is clear from these figures, it was revealed that the shielding film used in the present invention exhibits higher compressive elasticity and elongation elastic modulus than the cotton cloth constituting the base cloth layer.

FIG. 4 shows the result of measuring the surface tension of the printing blanket shown in FIG. 1 manufactured as described above. In the figure, □ indicates the case where the conventional shielding film is not used, and ● indicates the printing blanket of the present invention. As is clear from this figure, even if it is left under a fluorescent lamp for 50 days, it hardly changes to 15 to 16 dyne · cm ⁻¹ ,
Good printed matter was obtained. Further, the pattern accuracy was maintained at ± 10 μm.

[0024]

As described above, according to the blanket for offset printing of the present invention, the acceptance transfer characteristic does not change with time, the pattern shape is not disturbed, and further, the printing area of the printing area on the plate of the pattern area is not changed. This has the advantage that there is no printing error in position accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view of a blanket for offset printing according to the present invention.

FIG. 2 is a diagram showing changes in stress due to compressive strain.

FIG. 3 is a diagram showing a stress change due to tensile strain.

FIG. 4 is a diagram showing the results of measuring surface tension over time.

FIG. 5 is a cross-sectional view of a conventional offset printing blanket.

[Explanation of symbols]

 1 Acceptable Transfer Layer 2 Base Fabric Layer 21 Base Fabric Layer Underneath 3 Sponge Layer 4 Shielding Film 5 Adhesive Layer

Claims (5)

[Claims] 1. An offset printing blanket comprising a silicone rubber or silicone resin receptive transfer layer, a base fabric layer provided thereunder, and a lower rubber layer to which various compounding agents are added. A blanket for offset printing, characterized in that a shielding film is provided between the base fabric layers immediately below it. 2. The compression elasticity of the shielding film is 0.05.
The blanket for offset printing according to claim 1, wherein the blanket is about 0.20 kgf · mm ⁻² . 3. The extension elasticity of the shielding film is 0.2 to
The offset printing blanket according to claim 1 or 2, which has a 0.8% modulus of 100 to 500 kgf · m ⁻¹ . 4. The blanket for offset printing according to claim 1, wherein the thickness of the shielding film of the shielding film is 100 to 150 μm. 5. The blanket for offset printing according to claim 1, wherein the shielding film is a polyester film, PEN, PPS, a polyimide film, a stainless film, an aluminum film, or a copper film.