JPH08175048A - Printing blanket - Google Patents

Abstract

PURPOSE: To provide a printing blanket enhanced in durability while keeping printing quality (especially, image line edge shape, image line cross-sectional shape). CONSTITUTION: In a printing blanket transferring and reproducing fine patterns with high accuracy, the rubber layer forming the uppermost surface of the blanket is formed from silicone rubber of which the max. load value is larger than a stress concn. value generated by stress (4-50% modulus: M4-50) within a deformation ratio range of 4-50% (stress concn. value < max. load value) and the value of M25 of the rubber layer forming the uppermost surface of the blanket is 0.5-1.5kgf/cm<2> and the value of M50 thereof is 1.0-3.0kgf/cm<2> . The permanent compression strain of the silicone rubber layer forming the uppermost surface of the blanket is 60% or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing blanket used in an offset method in which ink is transferred from a printing plate to a blanket, and then the ink on the blanket is transferred to a printing material.

[0002]

2. Description of the Related Art Silicone rubber is chemically inert and has a low original surface tension (critical surface tension γ≈
20 °) Used for fixing rolls of fax machines, fax rolls, pad printing pads, etc. In recent years, particularly in the electro field, attention has been paid to the purpose of highly accurately transferring and reproducing a fine pattern. One of the uses in this electronics field is as a printing blanket for intaglio offset printing.

According to this method, there are advantages that a very sharp edge shape can be obtained, a thick film can be formed by printing once, and an electric wiring pattern using a conductor paste, a phosphor pattern, a plasma display. Used for color filters for liquid crystal display devices.

However, silicone rubber basically has low mechanical strength and good gas permeability, so that it has a drawback that it is easily plasticized. The above-mentioned copier rolls, fax rolls, etc. are used as toner transfer or backup rolls, etc. and do not come into direct contact with the uneven surface, but in the case of intaglio offset printing, the There is always a step of applying a constant pressure and pressing at least once, the mechanical damage by the intaglio edge is large, and the blanket surface is very likely to crack.

Further, the swelling of the blanket caused by the transfer of the ink from the intaglio plate to the blanket, which is caused by the ink solvent, has the effect of accelerating the plasticization of the surface and extracting the uncrosslinked low-molecular compounds in the blanket. There is. Phenomenon of this action appears as a minute depression of the ink contact portion on the blanket surface. It has been conventionally known that in the general world of commercial printing, there is a correlation between the surface deterioration (roughening and deformation) of a blanket and the deterioration of print quality. The wiring pattern. When characteristic values are prioritized over print quality (especially image edge shape, image line cross-sectional shape) such as fluorescent patterns and plasma displays, even if some surface deterioration of the blanket occurs, the effect on the product is relatively small. In the case of a product such as a color filter for a liquid crystal display device which is directly visually observed, the quality of the printed matter (particularly the image edge shape, the image line cross-sectional shape) directly determines the product quality.

Conventionally, the blanket has a multi-layer structure,
Moreover, although a layer for compressing raw material is provided in the intermediate layer to disperse the mechanical load applied to the surface layer and to adjust the wettability between the composition of the surface rubber layer and the ink composition, a silicone rubber blanket is used. It is not a decisive measure to prevent the deterioration of the surface. In particular, when printing with demanding printing quality such as color filters for liquid crystal display devices, surface conditions on the order of submicrons are required, so the blanket's service life is extremely short and improved durability is required. Has been done.

[0007]

SUMMARY OF THE INVENTION The present invention provides a printing blanket made of silicone rubber, which has improved durability while maintaining printing quality (particularly, drawing edge shape and drawing cross section shape). The challenge is to provide.

[0008]

In order to solve the above-mentioned problems, the present invention provides a printing blanket for transferring and reproducing a fine pattern with high accuracy, in which the maximum load value of a rubber layer forming the outermost surface of the blanket. Has a deformation rate of 4% to 50%
Stress in the range of (4% to 50% modulus: M4 to M
50) which is larger than the stress concentration value generated (stress concentration value <maximum load value) and the value of M25 of the rubber layer forming the outermost surface is 0.5 kgf / c.
The value of m ² or more 1.5 kgf / cm ² or less or M50 is printing blanket is 1.0 kgf / cm ² or more 3.0 kgf / cm ² or less. In printing blankets that transfer and reproduce fine patterns with high accuracy,
It is a printing blanket in which the compression set of the silicone rubber layer forming the outermost surface of the blanket is 60% or less.

As an embodiment of the present invention, the above-mentioned printing blanket, wherein the content of uncrosslinked low-molecular weight in the surface rubber layer forming the outermost surface of the blanket is from 5% by weight to 20% by weight, said outermost surface layer The above-mentioned printing blanket in which the silicone rubber layer forming the above contains 2 to 20% by weight of a straight-chain silicone raw rubber having an average molecular weight of 400000 to 1000000, and the surface rubber layer is on a base material (or base cloth) via a compression layer. Any of the printing blankets described above that have been formed.

The details will be described below. As described above, the deterioration of the shape of the silicone rubber blanket used for the intaglio offset printing is caused by cracks caused by stress concentration due to the edge of the intaglio, and the ink between the blanket and the printing medium (glass substrate, film, etc.) during ink transfer. This is caused by the crushing of the blanket that occurs when pressure is applied in the state of containing ink and the elution of soluble low-molecules from the blanket to the ink that also occurs when the blanket swells with the ink solvent (solvent, monomer, etc.) during ink transfer. There is a depression.

First, regarding the crack, the load value (printing pressure: value of M4 to M50) at the time of printing obtained from the experiment and the shape factor obtained from the sectional edge shape of the intaglio plate are used to obtain the following equation. The stress concentration value is obtained. Edge radius: ρ Rubber deformation amount: t Shape factor: α X% Modulus during deformation (stress during X% deformation): MX, α = 1 + 2 (t / ρ) ^1/2 (stress concentration value) = MX It is given by × α. The stress concentration value is compared with the maximum load value of the rubber material used for the surface rubber layer of the blanket. If (maximum load value)> (stress concentration value), no crack is generated in the surface rubber layer. In addition, when a rubber whose maximum load value decreases due to swelling (particularly room temperature curable silicone rubber that does not contain a filler component) is used, if (maximum load value during swelling)> (stress concentration value), cracking does not occur. Absent.

For the sake of explanation, a graph showing the relationship between (deformation rate) and (weighting) satisfying the condition for preventing the occurrence of cracks on the blanket surface when the shape factor α = 3 is shown in FIG. There are four main types,
In order to stabilize the printing characteristics, M25 is 0.
5kgf / cm ² or more, or M50 is 1kgf / c
Printing pressure of m ² or more is required.
Three types of B and C correspond to it.

However, the mechanical strength of silicone rubber is generally weak, and the maximum weight value cannot be made too large. Moreover, since the intaglio edge has an acute angle and the shape factor α is about 30, a considerable stress concentration occurs, and the modulus value in the vicinity of the printing pressure cannot be increased.
Therefore, in order to suppress the stress concentration value generated by the edge portion of the intaglio plate when applying the printing pressure and at the same time obtain a stable transfer transfer ability of the ink, it is necessary to suppress the modulus value near the printing pressure within an appropriate range. When M25 is selected as the modulus value near the printing pressure, 1.5 (kgf / cm ² ) ≧ M
25 ≧ 0.5 (kgf / cm ² ), when M50 is selected 3.0 (kgf / cm ² ) ≧ M50 ≧ 1 (k
The range of gf / cm ² ) (FIG. 2) is desirable.

Next, in the case of depression-like deterioration, this deterioration is caused by a combined effect of mechanical deformation caused by partial elastic loss of rubber and chemical deformation caused by dissolution of soluble low-molecular compounds in rubber. is there. Here, when the compression set characteristic is taken as the mechanical deformation characteristic value, the compression set characteristic is preferably 60% or less.

In order to prevent chemical deformation, soluble low-molecular compounds (residue of curing reaction, oil component such as dimethyl silicone, etc.) in the blanket should be removed. It is necessary to use a very small amount as a release agent having the effect of releasing the above from the silicone rubber surface, and the content is preferably 5 to 20% by weight. Alternatively, a rubber material from which soluble low molecular weight has been removed has an average molecular weight of 40
The same peeling effect can be obtained by adding about 2 to 20% by weight of a linear silicone raw rubber of about 0000 to 1,000,000. The blanket surface rubber layer having the above characteristics can be formed on the blanket base material (base cloth) alone or via the compression layer. The compression layer functions to absorb pressure unevenness during printing. In particular, it is possible to print with high dimensional accuracy by absorbing the thickness unevenness of the blanket when printing on a hard material to be printed and the thickness unevenness of the printing material itself.

[0016]

In the printing blanket of the present invention, the outermost silicone rubber layer is subjected to the above-mentioned conditions, so that the stress necessary for printing is generated and the stress concentration value at the edge of the intaglio plate is the maximum weight of the material. Since the value is not exceeded, the formation of cracks on the blanket surface can be prevented. Further, by optimizing the degree of crosslinking of the rubber by heat molding or the like to suppress the compression set and the amount of soluble low molecular weight to the necessary minimum, the depression-like shape deformation during continuous printing can be suppressed to be small.

[0017]

EXAMPLES As examples, only a single-layer blanket was shown, but since the outermost surface silicone rubber layer is particularly important, a comparison thereof was made. The layer may be a multi-layer with a commonly used substrate.

<Example 1> An LIM type silicone rubber coating solution having the following composition was applied to an aluminum plate having an anchor layer formed thereon by an applicator, and naturally dried at 25 ° C / 48 hours, and then 120 ° C / 20. Separated heating, thickness 60
A blanket was formed by forming a 0 μm surface rubber layer.

(1-1) Liquid heat-curable silicone rubber (LIM type) (KE-1940 manufactured by Shin-Etsu Chemical Co., Ltd.)
-30) A liquid and B liquid were each diluted with toluene to a solid content ratio of 60%, and dimethyl silicone oil (TSF451-1000 manufactured by Toshiba Silicone Co., Ltd.) was added to A liquid in an amount of 1%.
After adding 5% by weight, the solutions A and B were mixed.

(1-2) Liquid heat-curable silicone rubber (LIM type) (KE-193 manufactured by Shin-Etsu Chemical Co., Ltd.)
10% by weight of dimethyl silicone oil (TSF451-1000 manufactured by Toshiba Silicone Co., Ltd.) was added to the solution A of 4) and stirred, and then the solutions A and B were mixed. (In this case, 25 ℃
/ 48 hours of natural drying is not performed. )

COMPARATIVE EXAMPLE 1 Liquid heat-curable silicone rubber (LIM type) (KE-135 manufactured by Shin-Etsu Chemical Co., Ltd.)
4) Liquid A and liquid B were each added with toluene to obtain a solid content ratio of 50.
%, And dimethyl silicone oil (TSF451-1000 manufactured by Toshiba Silicone Co., Ltd.) in solution A is 15%
After the addition, solution A and solution B were mixed.

Example 2 A millable type silicone rubber coating solution having the following composition was applied on an aluminum plate having an anchor layer formed thereon by an applicator, and naturally dried at 25 ° C./48 hours, and then 170 ° C./15 Heating for 600 minutes
A blanket of the surface rubber layer was formed.

(2-1) Millable silicone rubber (TSE270-4U manufactured by Toshiba Silicone Co., Ltd.) was diluted with toluene to a solid content ratio of 20%, and dimethyl silicone oil (TSF451-100 manufactured by Toshiba Silicone Co., Ltd.) was diluted.
0) was added at 15%, and then the vulcanizing agent (2,5-dimethyl 2,5
-Ditertiary butyl peroxyhexane TC-8 manufactured by Toshiba Silicone Co., Ltd.) was added and mixed at 0.5% by weight.

(2-2) Millable silicone rubber (TSE221-3U, Toshiba Silicone Co., Ltd.) was diluted with toluene to a solid content ratio of 30%, and dimethyl silicone oil (TSF451-100, Toshiba Silicone Co., Ltd.) was diluted.
0) 10%, and then vulcanizing agent (2,5-dimethyl 2,5
-Ditertiary butyl peroxyhexane TC-8 manufactured by Toshiba Silicone Co., Ltd.) was added and mixed at 0.5% by weight.

Comparative Example 2 Millable silicone rubber (KE7014 manufactured by Shin-Etsu Chemical Co., Ltd.) was diluted with toluene to a solid content ratio of 30%, and dimethyl silicone oil (TSF451-1000 manufactured by Toshiba Silicone Co., Ltd.).
After adding 15% of vulcanizing agent, vulcanizing agent (bis, 2,4-dichlorobenzoyl peroxide manufactured by Shin-Etsu Chemical Co. Ltd.
1.3% of 2) was added and mixed.

Example 3 A room temperature curable (RTV) silicone rubber coating liquid having the following composition was applied on a plastic plate having an anchor layer formed thereon using an applicator, and the temperature was 25 ° C.
It was left to stand for / 24 hours for curing to form a blanket having a surface rubber layer of 600 μm.

(3-1) Room Temperature Curing (RTV) Methyl Vinyl Silicone (TSE34 manufactured by Toshiba Silicone Co., Ltd.)
53T) 80% by weight, room temperature curing type (RTV) methyl vinyl silicone (YE581 manufactured by Toshiba Silicone Co., Ltd.)
8) After mixing 10% by weight and 10% by weight of dimethyl silicone (TSF451-1000 manufactured by Toshiba Silicone Co., Ltd.), 10% by weight of a curing agent was added to each of the two types of methyl vinyl silicone from the outside, and the mixture was stirred again.

<Comparative Example 3> Room temperature curing (RTV) methyl vinyl silicone (TSE3 manufactured by Toshiba Silicone Co., Ltd.)
453T) 70%, room temperature curing (RTV) methyl vinyl silicone (YE5818 manufactured by Toshiba Silicone Co., Ltd.)
After mixing 25% and 5% of dimethyl silicone (TSF451-1000 manufactured by Toshiba Silicone Co., Ltd.), 10% by weight from the outside of each of the two types of methyl vinyl silicone.
The curing agent of was added and mixed again with stirring. The results of the above implementation are shown in (Table 1).

[0029]

[Table 1]

As a result of actual printing test, these blankets have a modulus value at 25% deformation of 1 kg.
/ Cm ² or more, and 10 to 15% by weight of inert dimethyl silicone oil was contained, the printability was good, but the load ratio was 1 or less (Comparative Example 1) and (Comparative Example 2) At the time of printing 500 times, uneven printing occurred due to blanket deterioration on the printed matter, and it was impossible to continue printing. As a result of observing the surface of the blanket used at this time, a crack was generated at a portion corresponding to the contact portion of the intaglio, and surface fracture due to stress concentration was observed.

Further, when the compression set was 75% (Comparative Example 3), printing unevenness due to blanket deterioration appeared on the surface of the printed matter at the time when about 500 printings were completed, and it became impossible to continue printing. Similarly, as a result of observing the surface of this blanket, a partial depression shape was observed at a portion corresponding to the intaglio contact portion, and permanent deformation of rubber was confirmed.
The printed blankets (Examples) other than (Comparative Example 1) to (Comparative Example 3) had no print unevenness after about 500 runs, and after about 800 runs were printed. The above was not found in the printed matter evaluation of.

[0032]

The printing blanket of the present invention is a blanket.
Maximum load of silicone rubber layer forming the outermost surface of the ket
Generated by stress in the range of deformation rate 4% to 50%
Greater than stress concentration value ((stress concentration value) <(maximum load
Value)) Made of silicone rubber and forms the outermost surface
The value of M25 of the silicone rubber layer is 0.5 kgf / cm
²Above, since the compression set is 60% or less,
Maintains print quality (particularly line edge shape, line cross section shape)
And provide a printing blanket with improved durability.
Can be

[0033]

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between (deformation rate) and (weight).

FIG. 2 shows (deformation rate) and (weighting) in the vicinity of printing pressure, and shows a desirable range with diagonal lines.

Claims (5)

[Claims] 1. In a printing blanket for transferring and reproducing a fine pattern with high accuracy, a maximum load value of a rubber layer forming an outermost surface of the blanket is a stress (4%) in a deformation ratio range of 4% to 50%. -50% modulus: M4 to M5
0) which is larger than the stress concentration value (stress concentration value <maximum load value), and the value of M25 of the rubber layer forming the outermost surface is 0.5 kgf / cm.
Printing blanket which the value of ² or more 1.5 kgf / cm ² or less or M50 is equal to or is 1.0 kgf / cm ² or more 3.0 kgf / cm ² or less. 2. A printing blanket for transferring and reproducing a fine pattern with high precision, wherein the compression set of the silicone rubber layer forming the outermost surface of the blanket is 60% or less. 3. The printing according to claim 1 or 2, wherein the content of uncrosslinked low-molecular weight compounds in the surface rubber layer forming the outermost surface of the blanket is 5% by weight to 20% by weight. blanket. 4. The printing blanket according to claim 1 or 2, wherein the silicone rubber layer forming the outermost surface layer contains 2 to 20% by weight of a straight-chain silicone raw rubber having an average molecular weight of 400000 to 1000000. . 5. The printing according to any one of claims 1 to 4, wherein the surface rubber layer is formed on a base material (or a base cloth) via a compression layer. Blanket.