JP2011126248A - Silicone bracket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone bracket, which can improve the productivity of a product by reducing the cycle time of printing through omission of a solvent removal step or reduction in the execution frequency thereof in the course of printing, since a surface layer has appropriate hardness to eliminate the possibility of deterioration of strength or printing accuracy, or the like, and significant rise of wettability of the surface of the surface layer can be suppressed over a long period of time to allow continuation of satisfactory printing. <P>SOLUTION: In the silicone bracket, the surface layer composed of dimethyl silicone rubber which constitutes a surface for supporting printing ink contains 10 pts.mass or more and 100 pts.mass or less of phenylmethyl silicone gel based on 100 pts.mass of the dimethyl silicone rubber. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a silicone blanket used in a printing method such as an offset printing method.

The offset printing method has an advantage that an ink pattern can be formed easily and efficiently with a small number of steps and at a low cost, and since printing accuracy has been improved in recent years, Use is spreading in the electronics field.
For example, in fields where fine and high-precision patterns are required, such as electrical wiring patterns, phosphor patterns, and various patterns in plasma display panel (PDP) and liquid crystal display panel (LCD) components, etc. In place of pattern formation by the conventional photolithographic method, an offset printing method has become widespread.

In the offset printing method, a pattern is printed on the surface of the substrate by transferring the ink patterned on the surface of the plate to the surface of the blanket and then transferring it again to the surface of the substrate as the substrate. .
As the blanket, a silicone blanket provided with at least a surface layer constituting the surface, and the surface layer formed of silicone rubber having excellent releasability with respect to ink is widely used.

Since the surface layer is repeatedly contacted with the ink, the solvent contained in the ink is impregnated and gradually swelled as printing is repeated, and the wettability of the surface with respect to the ink gradually increases accordingly. Therefore, it is difficult to keep the printing accuracy at a high level over a long period from the initial printing.
If an ink containing a solvent with low wettability that hardly swells silicone rubber is used, the wettability hardly changes even when printing is repeated, so that it seems that stable printing can be performed. However, an ink containing a solvent with low wettability has a low transferability from the surface of the plate to the surface of the surface layer, and therefore breakage is likely to occur particularly in a fine line pattern.

  The disconnection is one of the most problems to be avoided, and in order to prevent this, a solvent that can swell silicone rubber to some extent must be used. However, when printing is repeated using an ink containing such a solvent, the surface layer is gradually swollen by the solvent, and the wettability with respect to the ink is gradually increased. Along with this, the ink tends to bleed, and in particular, the line width of the fine line pattern gradually widens, or fine stains on the plate surface are transferred, or the ink from the surface layer surface to the substrate surface The transferability of the ink gradually decreases, and the printing accuracy gradually decreases.

It is conceivable to remove the solvent that swells the surface layer by heating the silicone blanket. However, in order to do so, it is necessary to heat the silicone blanket to about 40 to 200 ° C. If the surface having a high temperature immediately after heating is brought into contact with the plate, the plate is thermally expanded, and the printing accuracy is lowered. is there.
It has been proposed to remove a solvent by bringing a solvent absorber having a function of absorbing the solvent into contact with the surface of the surface layer (see Patent Document 1). If the solvent absorber is used, the solvent can be removed without heating the silicone blanket, so that the printing accuracy can be maintained at a high level.

  However, the removal of the solvent by the solvent absorber needs to be carried out after stopping printing every one to several times in order to keep the swelling state of the surface layer constant. After setting the substrate on the printing machine and printing the ink on the surface of the substrate according to a predetermined procedure to form a pattern, the average time required to set a new substrate on the printing machine is increased. There is a problem of reducing the productivity of the product.

Patent Document 2 describes that a predetermined amount of silicone gel is contained in a surface layer made of silicone rubber.
Silicone gel has basically the same polysiloxane structure as silicone rubber, but has a crosslinking density after crosslinking reaction that is lower than silicone rubber and hardens into a soft gel that cannot be measured with a normal rubber hardness meter. Say.

  Such a silicone gel is excellent in the ability to absorb a solvent as compared with the silicone rubber forming the surface layer. Therefore, by selectively absorbing the solvent with the silicone gel contained in the surface layer, it is possible to suppress the surface wettability of the surface layer from significantly increasing in a short period of time, and to remove the solvent by the solvent absorber or the like. It is conceivable to omit the step or reduce the number of times the step is performed.

JP 2006-188015 A JP 2008-49495 A

  However, as is clear from the results of Examples and Comparative Examples described below, the combination of dimethylsilicone rubber and dimethylsilicone gel, whose effect has been studied in the Examples of Patent Document 2, makes the surface layer too soft and strong. There arises a problem that the printing pressure or nip width at the time of printing or the contact with the plate or the substrate during printing is greatly changed and printing properties are lowered, and as a result, printing accuracy is lowered.

  The object of the present invention is to prevent the surface layer from having a significant increase in the wettability of the surface layer over a long period of time, since the surface layer has an appropriate hardness, so there is no risk of a decrease in strength or printing accuracy. Providing a silicone blanket that can improve the productivity of products by shortening the tact time of printing by omitting the solvent removal process during the printing or reducing the number of executions because good printing can be continued. There is.

  The present invention is a printing silicone blanket, comprising at least a surface layer made of silicone rubber that constitutes a surface for carrying the printing ink, and the silicone rubber forming the surface layer is dimethyl silicone rubber. The surface layer contains 10 to 100 parts by mass of phenylmethylsilicone gel per 100 parts by mass of the dimethyl silicone rubber.

  According to the present invention, a printing layer made of dimethyl silicone rubber contains phenylmethyl silicone gel which is a kind of silicone gel at a ratio of 10 parts by mass or more per 100 parts by mass of the dimethyl silicone rubber. The solvent contained therein and the solvent impregnated in the surface layer is selectively absorbed by the phenylmethyl silicone gel to suppress the swelling of the silicone rubber, and the wettability of the surface layer made of the silicone rubber is increased. It is possible to continue the good printing by suppressing this over a long period of time.

  Further, as apparent from the results of Examples and Comparative Examples described later, the phenylmethylsilicone gel is contained at a ratio of 100 parts by mass or less per 100 parts by mass of dimethylsilicone rubber, thereby increasing the hardness of the surface layer. It can be maintained at the same level as when it is made of dimethyl silicone rubber alone. As a result, the surface layer becomes too soft and the strength is reduced, or the printing pressure and nip width when contacting the plate or substrate during printing are greatly changed, resulting in a decrease in printability, resulting in a decrease in printing accuracy. Can be prevented.

  The silicone blanket of the present invention preferably comprises a film-like or sheet-like substrate and the surface layer formed on one side of the substrate. By providing the base material, it is possible to maintain the strength of the entire silicone blanket and to ensure good handleability.

  According to the present invention, since the surface layer has an appropriate hardness, there is no risk of a decrease in strength or printing accuracy, and the surface layer surface wettability is prevented from greatly increasing over a long period of time. Providing a silicone blanket that can improve the productivity of products by shortening the tact time of printing by omitting the solvent removal process during the printing or reducing the number of executions because good printing can be continued. be able to.

  The silicone blanket of the present invention comprises at least a surface layer made of silicone rubber, which constitutes a surface for carrying printing ink, and the silicone rubber forming the surface layer is dimethyl silicone rubber, It contains 10 to 100 parts by weight of phenylmethylsilicone gel per 100 parts by weight of dimethyl silicone rubber.

Examples of the dimethyl silicone rubber that forms the surface layer include various dimethyl silicone rubbers, and liquid dimethyl silicone rubber that exhibits a liquid or paste form when uncured is particularly preferable.
The liquid or paste-like dimethyl silicone rubber can form a surface layer by applying a predetermined thickness on a substrate using, for example, a doctor knife, a bar coater, a roll coater, etc., and then curing. At that time, by the so-called self-leveling effect, the surface of the coating film that becomes the basis of the surface layer, that is, the surface of the surface layer after curing can be smoothed and the thickness of the surface layer can be made uniform.

Therefore, a silicone blanket with a surface layer with excellent surface smoothness that is suitable for forming fine and high-precision patterns on the surface of the substrate as the substrate to be printed is manufactured with high productivity without passing through polishing and other processes. it can. Needless to say, the surface of the surface layer may be polished as necessary.
The silicone blanket is produced by injecting and curing the liquid or pasty dimethyl silicone rubber having a shaping surface corresponding to the surface shape of the surface layer into a mold on which a substrate is set. May be.

  The dimethyl silicone rubber is preferably a room temperature curable type (RTV). The room temperature curing type dimethyl silicone rubber can be cured at room temperature (5-35 ° C) without heating as the name suggests, thus simplifying the silicone blanket manufacturing process and manufacturing equipment. In addition, since it does not undergo expansion due to heating and shrinkage during cooling, the accuracy of the thickness of the surface layer can be improved.

Further, the dimethyl silicone rubber is preferably a two-component addition reaction type which is composed of two components of a main agent and a curing agent and can cure both of them by an addition reaction.
The two-component addition reaction type dimethyl silicone rubber does not produce a by-product during the curing reaction, and thus improves the dimensional accuracy of the surface layer and can form a uniform surface layer that does not contain bubbles or the like based on the by-product. .

  Examples of the room temperature curing type two-component addition reaction type liquid dimethylsilicone rubber include, for example, product numbers KE1600, KE1603, KE1606, KE1310ST, KE1300T, KE1314, KE1241, KE106, KE103, manufactured by Shin-Etsu Chemical Co., Ltd., Momentive Performance. -Product numbers TSE3402, TSE3453, TSE3455T, TSE3457, TSE3466, etc. manufactured by Materials are listed.

  The dimethyl silicone rubber is measured in an environment of a temperature of 23 ± 3 ° C. and a relative humidity of 55 ± 5% when cured alone without containing phenylmethyl silicone gel. Japanese Industrial Standard JIS K6253: It is preferable that the type A durometer hardness defined in 2006 “Vulcanized rubber and thermoplastic rubber—How to obtain hardness” is A10 / S or more, particularly A20 / S or more.

As a result, the surface layer becomes too soft and the strength is reduced, the printing pressure when contacting the plate or the substrate during printing, the nip width, etc. greatly change, causing problems in printability, or the printing accuracy is increased. It can control that it falls.
The surface layer becomes too hard, and the transferability of the ink from the surface of the plate to the surface of the surface layer is deteriorated, or the printing shape is disturbed due to the influence of subtle irregularities on the surface of the surface layer. In view of preventing this, the dimethyl silicone rubber has a type A durometer hardness of A80 / S or less, particularly A60 / S or less, when cured alone without containing phenylmethylsilicone gel. preferable.

The silicone gel contained in the surface layer is basically a soft gel that has the same polysiloxane structure as silicone rubber, but has a crosslinking density after the crosslinking reaction that is smaller than that of silicone rubber and cannot be measured with a normal rubber hardness meter. The one that hardens into a shape.
In the present invention, as the silicone gel, a phenylmethyl silicone gel in which a part of the methyl groups in the side chain of dimethylpolysiloxane is substituted with a phenyl group is used. Thereby, compared with the case where the conventional dimethyl silicone gel is contained, the hardness of the surface layer can be maintained at the same level as the case where it is made of dimethyl silicone rubber alone. As a result, the surface layer becomes too soft and the strength is reduced, or the printing pressure and nip width when contacting the plate or substrate during printing are greatly changed, resulting in a decrease in printability, resulting in a decrease in printing accuracy. Can be prevented.

As the phenylmethyl silicone gel, liquid phenylmethyl silicone gel is preferable in consideration of forming a smooth surface layer by the self-leveling effect described above.
In addition, as the phenylmethylsilicone gel, various one-component and two-component phenylmethylsilicone gels can be used. As the dimethylsilicone rubber, the two-component addition reaction type described above is used. In this case, the phenylmethylsilicone gel to be combined is composed of two components of a main agent and a curing agent in order to prevent inhibition of the curing reaction of the dimethylsilicone rubber, and the two can be cured by an addition reaction. It is preferable to use a liquid addition reaction type phenylmethyl silicone gel.

Examples of the two-component addition-type liquid phenylmethylsilicone gel include product numbers IVS5022, XE14-C2860 manufactured by Momentive Performance Materials.
The content ratio of the phenylmethyl silicone gel is limited to a range of 10 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the dimethyl silicone rubber.

When the content ratio is less than the above range, the wettability of the surface layer of the surface layer increases over a long period of time by allowing the solvent to be selectively absorbed by the phenylmethylsilicone gel by including the phenylmethylsilicone gel. It is not possible to obtain the effect of suppressing printing and continuing good printing.
On the other hand, when the content ratio exceeds the above range, the surface tension of the surface layer becomes too large, and the transferability of the ink is lowered, or the strength of the surface layer is lowered and the surface layer is easily damaged.

  The content ratio of the phenylmethylsilicone gel further increases the amount of the solvent that can be absorbed, and considering that the wettability of the surface layer surface is increased over a longer period, etc. The amount is preferably 20 parts by mass or more. Also, the surface layer becomes too soft and the strength is reduced, the printing pressure and nip width when contacting the plate or substrate during printing changes greatly, causing problems in printability, or the printing accuracy decreases. In view of suppressing the occurrence of such a problem, the amount is preferably 50 parts by mass or less even within the above range.

The thickness of the surface layer is preferably 0.1 mm or more and 1 mm or less in the case of a precision printing silicone blanket that requires high printing accuracy, such as the PDP and LCD patterns described above.
The hardness of the surface layer is not less than A25 / S in terms of type A durometer hardness measured in an environment of a temperature of 23 ± 3 ° C. and a relative humidity of 55 ± 5% as defined in the above-mentioned JIS K6253: 2006. In particular, it is preferably A30 / S or more, more preferably A60 / S or less, and particularly preferably A50 / S or less.

Further, the surface state of the silicone blanket is preferably as flat as possible because the finer the ink pattern, the more influence is exerted on the accuracy. For example, the surface roughness of the above-mentioned silicone blanket for precision printing can be found in Japanese Industrial Standard JIS B0601: 2001 “Product Geometrical Specification (GPS) —Surface Properties: Contour Curve Method—Terminology, Definitions, and Surface Property Parameters” Annex 1 It is preferable that it is 0.01 μm or more and 1 μm or less in ten-point average roughness Rz _JIS94 defined by

The silicone blanket of the present invention preferably comprises a film-like or sheet-like substrate and the surface layer formed on one side of the substrate. By providing the base material, it is possible to maintain the strength of the entire silicone blanket and to ensure good handleability.
Examples of the base material include various resin films or sheets, metal thin plates, and the like. Among these, as a resin film or sheet, polyethylene terephthalate (PET), polyvinyl chloride, polyethylene, polypropylene, polystyrene and copolymers thereof, polyvinylidene chloride, polyvinyl alcohol, fluororesin, polycarbonate, cellulose acetate, polyamide, polyimide, Examples thereof include films or sheets made of resins such as modified polyphenylene ether, polysulfone, polyarylate, polyethersulfone, polyetheretherketone, polyetherimide, polyphenylene sulfide, TPX polymer, and polyparaxylene.

The metal thin plate is preferably a thin plate made of a metal such as copper or an alloy thereof, aluminum or an alloy thereof, stainless steel, or nickel.
In particular, it is preferable to use as a substrate a PET film or sheet that is easily processed into a film or sheet having an arbitrary thickness and surface roughness and that is excellent in dimensional stability.
In the case of the silicone blanket for precision printing, the thickness of the substrate is preferably 0.05 mm or more and 0.5 mm or less.

In order to improve the adhesion of the surface layer, the surface of the base material before forming the surface layer may be subjected to pretreatment such as plasma treatment or flame treatment, or an arbitrary underlayer may be formed. Good.
The silicone blanket of the present invention is, for example,
(1) An offset printing method in which an ink patterned on the surface of a plate such as an intaglio plate or a lithographic plate is transferred to the surface of a silicone blanket and then re-transferred to the surface of a substrate as a substrate.
(2) The ink is applied to the entire surface of the silicone blanket and then brought into contact with the intaglio, thereby selectively removing the ink in contact with the area other than the concave portion of the intaglio from the surface of the silicone blanket. After pattern formation, the reverse printing method of transferring to the surface of the substrate,
(3) a printing method in which an ink pattern is drawn directly on the surface of the silicone blanket and then transferred to the surface of the substrate;
It can be used for various printing methods.

  When performing continuous printing using the various printing methods, according to the silicone blanket of the present invention, the solvent contained in the ink and impregnated in the surface layer is phenylmethyl containing the surface layer. By selectively absorbing with the silicone gel, swelling of the dimethyl silicone rubber can be suppressed, and an increase in the wettability of the surface layer of the dimethyl silicone rubber can be suppressed over a long period of time. Therefore, it is possible to improve the productivity of products such as PDP by omitting the solvent removing step during printing and shortening the tact time of printing.

  Moreover, by the action of the phenylmethyl silicone gel, the hardness of the surface layer can be maintained at the same level as in the case where the dimethyl silicone rubber is made alone, unlike the case where the conventional dimethyl silicone gel is contained. As a result, the surface layer becomes too soft and the strength is reduced, or the printing pressure and nip width when contacting the plate or substrate during printing are greatly changed, resulting in a decrease in printability, resulting in a decrease in printing accuracy. Can be prevented.

The following examples and comparative silicone blankets were manufactured, measured for properties, and tested in an environment of 23 ± 3 ° C. and 55 ± 5% relative humidity unless otherwise specified.
<Example 1>
91 parts by mass of main component of room temperature curable and two-component addition reaction type liquid dimethyl silicone rubber (product number TSE3450 manufactured by Momentive Performance Materials), and also a room temperature curable and two-component addition reaction type liquid 7.5 parts by mass of a main ingredient of phenylmethyl silicone gel [the above-mentioned, product number IVS5022 manufactured by Momentive Performance Materials, Inc.] was mixed. Further, 9 parts by mass of the liquid dimethyl silicone rubber curing agent and 7.5 parts by mass of liquid phenylmethyl silicone gel curing agent were mixed.

The mass ratio of the main component and the curing agent of the liquid dimethyl silicone rubber was 91: 9, and the mass ratio of the main component and the curing agent of the liquid phenylmethyl silicone gel was 1: 1.
Next, the mixture is mixed and degassed to prepare a coating solution for the surface layer. The coating solution is applied to one side of a PET film having a thickness of 0.25 mm as a substrate using a bar coater and then at room temperature. It was allowed to stand for 24 hours for a curing reaction to form a surface layer having a thickness of 0.70 mm and a PET film having a dimension of 80 cm in length and 80 cm in width in the plane direction to produce a silicone blanket.

The total content of the phenylmethylsilicone gel main agent and the curing agent per 100 parts by mass of the dimethyl silicone rubber main agent and the curing agent in the surface layer was 15 parts by mass.
<Comparative example 1>
A coating solution was prepared in the same manner as in Example 1 except that only the main component of liquid dimethylsilicone rubber and the curing agent used in Example 1 were mixed at a mass ratio of 91: 9 to produce a silicone blanket.

In the surface layer of the silicone blanket, the total content of phenylmethylsilicone gel main agent and curing agent per 100 parts by mass of dimethyl silicone rubber main agent and curing agent total was 0 part by mass.
<Examples 2 and 3, Comparative Examples 2 and 3>
When preparing the coating liquid, the amount of liquid phenylmethylsilicone gel main ingredient and curing agent is adjusted, and in the surface layer, the main ingredient of dimethyl silicone rubber and the main ingredient of phenylmethylsilicone gel per 100 parts by mass of the curing agent Except that the total content of the curing agent was 5 parts by mass (Comparative Example 2), 50 parts by mass (Example 2), 90 parts by mass (Example 3), and 120 parts by mass (Comparative Example 3). A silicone blanket was produced in the same manner as in Example 1.

As in Example 1, the mass ratio of the main component of liquid dimethyl silicone rubber to the curing agent was 91: 9, and the mass ratio of the main component of liquid phenylmethyl silicone gel to the curing agent was 1: 1.
<Comparative example 4>
In place of the main component and curing agent of liquid phenylmethylsilicone gel, the main component and curing agent of liquid dimethyl silicone gel [Product No. TSE3062 manufactured by Momentive Performance Materials Co., Ltd.] were blended, and the blending amount was adjusted. A coating solution was prepared in the same manner as in Example 1 to produce a silicone blanket.

The mass ratio of the main component of liquid dimethyl silicone rubber to the curing agent was 91: 9, and the mass ratio of the main component of liquid dimethyl silicone gel to the curing agent was 1: 1.
In the surface layer of the silicone blanket, the total content of the dimethyl silicone gel main agent and the curing agent per 100 parts by mass of the dimethyl silicone rubber main agent and 100 parts by mass of the curing agent was 50 parts by mass.

<Hardness measurement>
The type A durometer hardness of the surface layer of the silicone blanket produced in Examples and Comparative Examples was measured in accordance with the above-mentioned JIS K6253: 2006.
<Printing characteristic test>
After cutting the silicone blanket manufactured in Examples and Comparative Examples into a predetermined size, a surface layer is formed on the outer periphery of the blanket cylinder of an intaglio offset printing machine (a flat precision printing machine compatible with 300 mm × 400 mm manufactured by Nakan Co., Ltd.). Was wound and fixed. Further, as the intaglio, a glass plate was used in which concave portions having a line width of 100 μm, a pitch of 200 μm, and a depth of 40 μm were formed in a lattice pattern.

The ink used was prepared by kneading polyester resin, butyl carbitol acetate as a solvent, and silver powder as a pigment using three rolls.
The printing conditions were 100 mm / s for the ink transfer speed from the concave part of the intaglio plate to the surface of the surface layer of the silicone blanket, and the ink transfer speed from the surface of the surface layer to the surface of the glass substrate as the printing medium. Setting to 100 mm / s, continuous printing was performed 30 times while replacing the glass substrate.

After the 30th printing, the surface of the surface layer of the silicone blanket and the pattern printed on the surface of the glass substrate were observed, and the printing characteristics were evaluated according to the following criteria.
◯: No ink remained due to transfer failure on the surface of the surface layer, and almost no increase in line width was observed in the pattern printed on the surface of the glass substrate.
Δ: Ink residue due to transfer failure was not observed, but a slight increase in the line width of the pattern was observed.

X: Residual ink due to transfer failure was observed, and the increase in line width was also large.
Moreover, the pattern printed on the surface of the glass substrate of the 30th printing was observed, and the quality of the printed shape was evaluated according to the following criteria.
A: No disturbance was observed in the pattern.
Δ: Slight disturbance was observed in the pattern, but it was within an acceptable range.

X: The pattern was so disturbed that the product could not be used.
The above results are shown in Tables 1 and 2.

From both tables, the silicone blanket of Comparative Example 1 in which the silicone gel was not contained in the surface layer and Comparative Example 2 in which the content ratio of phenylmethyl silicone gel was less than 10 parts by mass per 100 parts by mass of dimethyl silicone rubber was It has also been found that by repeating printing, the wettability of the surface layer is greatly increased, resulting in an increase in line width, poor transfer, and the like.
Further, it was found that the printing accuracy of the silicone blanket of Comparative Example 3 containing more than 100 parts by mass of phenylmethyl silicone gel per 100 parts by mass of dimethyl silicone rubber was lowered.

Furthermore, the silicone blanket of Comparative Example 4 containing conventional dimethylsilicone gel instead of phenylmethylsilicone gel showed a slight disturbance in the pattern because the surface layer became too soft.
On the other hand, according to the silicone blankets of Examples 1 to 3, printing was repeated while maintaining the hardness of the surface layer to the same level as when made of a single dimethyl silicone rubber and ensuring strength and printing accuracy. In this case, it was found that the increase in the wettability of the surface layer on the surface layer can be suppressed to prevent the increase in line width and the occurrence of transfer failure.

Claims (2)

  A silicone blanket for printing, comprising at least a surface layer made of silicone rubber constituting a surface for carrying the printing ink, wherein the silicone rubber forming the surface layer is dimethyl silicone rubber, and the surface layer Contains 10 parts by mass or more and 100 parts by mass or less of phenylmethylsilicone gel per 100 parts by mass of the dimethyl silicone rubber.   The silicone blanket of Claim 1 provided with the base material of a film form or a sheet form, and the said surface layer formed in the single side | surface of the said base material.