JP4913196B2 - Solvent absorber - Google Patents

Description

  The present invention relates to a printing method for transferring the ink carried on the surface of the silicone blanket to the surface of the substrate to be printed and printing a predetermined pattern made of the ink on the surface. The present invention relates to a solvent absorber used for absorbing and removing a solvent impregnated in a silicone blanket.

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. Instead of pattern formation by the conventional photolithographic method, the 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 in which at least the surface thereof is formed of silicone rubber or silicone resin excellent in releasability to ink is widely used.

  Since the silicone blanket is repeatedly contacted with the ink, particularly when the substrate to be printed is made of a material that does not absorb the solvent such as a glass substrate, the silicone blanket is gradually impregnated with the solvent contained in the ink while the printing is repeated. As a result, the wettability of the surface of the silicone blanket to the ink gradually increases. 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 or silicone resin 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 having low wettability is less receptive from the surface of the plate to the surface of the silicone blanket, and therefore, breakage is likely to occur particularly in a fine line pattern.

  Disconnection is one of the most unavoidable defects that must be avoided by using a solvent that can swell the silicone blanket to some extent. However, when printing is repeated using the ink containing the solvent, the silicone blanket gradually swells, the wettability with respect to the ink gradually increases, and the releasability gradually decreases. As the wettability increases, the ink easily spreads, and the line width of the fine line pattern is gradually widened, minute stains on the plate surface are transferred, and the releasability is reduced. As a result, the transferability of the ink from the silicone blanket to the substrate gradually decreases, and the printing accuracy decreases.

It is considered to remove the swollen solvent 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. When a silicone blanket having a high surface temperature immediately after heating is brought into contact with the plate, the plate is thermally expanded and printing accuracy is reduced. There's a problem.
It has been proposed that a solvent absorber having a function of absorbing a solvent is brought into contact with the surface of the silicone blanket, and the solvent impregnated in the silicone blanket is moved to the solvent absorber to be removed (Patent Document 1). 2). According to this method, since the solvent can be removed without heating the silicone blanket, the printing accuracy can be maintained at a high level. The removal of the solvent by the solvent absorber is performed once to several times of printing.

  The solvent absorber used in the above method is generally constituted by laminating a single-layer absorption layer made of silicone rubber or silicone resin, which is substantially equivalent to the surface of the silicone blanket, on at least one surface of the substrate.

JP-A-8-156388 JP 2009-119709 A

  However, the absorption layer of the conventional solvent absorber is almost equivalent to the silicone blanket in terms of the ease of solvent absorption, and merely absorbs the solvent based on the concentration difference of the impregnated solvent. First, while repeating the operation of absorbing the solvent by bringing it into contact with the surface of the silicone blanket, the absorbed layer itself swells due to the absorbed solvent and tends to become difficult to absorb the solvent gradually.

Therefore, for example, it is considered to set the number of times of use of the solvent absorber in advance and replace the solvent absorber with a new one when the predetermined number of times of use is reached.
Specifically, for example, the solvent absorber is formed in a long belt shape and wound into a roll, and a predetermined length region of the solvent absorber fed from the roll is brought into contact with the surface of the silicone blanket to form a solvent. Is performed once or several times using the same region, and each time the predetermined operation is performed, a new region of the solvent absorber is unwound from the roll and used for absorbing the solvent in the same manner. This is being considered.

In addition, the solvent absorber is formed in an endless belt shape, and the solvent absorber is heated every time one or several times when the solvent absorber is rotated and brought into contact with the surface of the silicone blanket to absorb the solvent. It has also been studied to repeatedly use the solvent absorber for solvent absorption while removing the absorbed solvent.
However, whatever operation is performed, printing must be stopped in the meantime. Therefore, the more frequently these operations are performed, the more takt time of the offset printing method, that is, the substrate is set in the offset printing machine. Productivity of products manufactured by the offset printing method is increased by printing the ink on the surface of the substrate according to the procedure, and increasing the average time required to set a new substrate on the offset printing machine. This causes the problem of lowering.

In addition, it is not desirable from the viewpoint of resource saving and energy saving to frequently perform the operation of exchanging the solvent absorber or removing the solvent by heating as described above.
An object of the present invention is to provide a novel solvent absorber capable of improving the productivity of a product by shortening the tact time of the printing because it is not necessary to frequently perform replacement and solvent removal operations as compared with the prior art. It is in.

The present invention comprises a film-like or sheet-like base material and an absorbent layer formed on at least one side of the base material, and is contained in an ink used for a printing method using a silicone blanket and impregnated in the silicone blanket. A solvent absorber for absorbing and removing a solvent by contacting the surface of the absorbent layer with the surface of the silicone blanket by the absorbent layer, wherein the absorbent layer is made of silicone rubber or silicone resin. And a layered structure of two or more layers including a surface layer that does not contain bubbles , constituting the surface, and is made of silicone rubber or silicone resin on the substrate side from the surface layer, and has a higher swelling rate of the solvent than the surface layer A solvent absorber comprising a layer that does not contain bubbles .

  The swelling rate is the amount of solvent that a given layer of rubber or resin can absorb within a certain time starting from a dry state that does not absorb any solvent, that is, how much solvent the layer is from the dry state. It is an index indicating whether or not it has the ability to absorb, and the higher the swelling rate, the better the layer is to absorb the solvent, indicating that more solvent can be absorbed within a certain time.

As a result of investigation by the inventors, when two layers having different swelling ratios are laminated and a solvent having a lower swelling ratio is impregnated with a solvent, the impregnated solvent has a swelling ratio based on the difference in swelling ratio. The phenomenon of moving to the higher layer occurs.
The present invention utilizes this phenomenon, and as described above, the absorption layer is made of a silicone rubber or a silicone resin , and has a laminated structure of two or more layers including a surface layer containing no air bubbles inside thereof. On the substrate side (lower side), a layer made of silicone rubber or silicone resin, which has a higher solvent swelling rate than the surface layer and does not contain bubbles, is placed in the solvent absorption step. Most of the solvent that has moved from the blanket to the absorbent layer does not stay on the surface layer but moves to the lower layer based on the difference in the swelling rate.

For this reason, the surface of the absorbent layer, which is the surface of the absorbent layer, can be maintained for a relatively long time in a state where the amount of impregnation of the solvent is small and the solvent is easily absorbed, and the frequency of replacement and solvent removal operations is less frequent than before. In addition, it is possible to shorten the printing tact time and improve the productivity of the product.
In the present invention, the swelling rate is expressed as a value obtained by the following measurement under an environment of a room temperature of 23 ± 1 ° C. and a relative humidity of 55 ± 1%.

That is, first, each sample is made of the same material that forms each layer (surface layer, etc.) constituting the absorption layer, and after measuring the mass W ₁ of the sample in a dry state in which no solvent is absorbed, Immerse so that the entire sample is immersed in the solvent contained in the ink actually used, and let stand for 2 hours.
Next, the mass W ₂ of the sample immediately after being pulled out of the solvent is measured, and the formula (1):
Swelling ratio (%) = [(W ₂ −W ₁ ) / W ₁ ] × 100 (1)
Thus, a swelling rate (%) as a rate of mass change due to swelling of the solvent is obtained.

The absorbent layer preferably has a two-layer structure of the surface layer and a lower layer having a higher solvent swelling ratio than the surface layer. Thereby, the structure can be simplified as much as possible to improve the productivity of the solvent absorber.
The surface layer is preferably formed of the same kind of silicone rubber or silicone resin as that forming the surface of the silicone blanket. Thereby, the adhesiveness of the surface of the absorption layer to the surface of the silicone blanket can be improved, and the solvent impregnated in the silicone blanket can be absorbed and removed by the absorption layer as smoothly as possible.

  Further, the surface of the silicone blanket can be prevented from being contaminated by contact with different materials, and the surface state can be kept constant.

  According to the present invention, since it is not necessary to frequently perform replacement and solvent removal operations as compared with the prior art, it is possible to provide a novel solvent absorber that can shorten the tact time of printing and improve the productivity of the product. it can.

The present invention comprises a film-like or sheet-like base material and an absorbent layer formed on at least one side of the base material, and is contained in an ink used for a printing method using a silicone blanket and impregnated in the silicone blanket. A solvent absorber for absorbing and removing a solvent by contacting the surface of the absorbent layer with the surface of the silicone blanket by the absorbent layer, wherein the absorbent layer is made of silicone rubber or silicone resin. And a layered structure of two or more layers including a surface layer that does not contain bubbles , constituting the surface, and is made of silicone rubber or silicone resin on the substrate side from the surface layer, and has a higher swelling rate of the solvent than the surface layer In addition, a layer that does not contain bubbles is provided.

Surface of said absorbent layer, you formed by said silicone rubber or silicone resin as (hereinafter sometimes collectively referred to as "silicone rubber"). Thereby, the adhesiveness of the surface of the absorption layer to the surface of the silicone blanket is enhanced, and the solvent impregnated in the silicone blanket can be absorbed and removed by the absorption layer as smoothly as possible. Further, the surface of the silicone blanket can be prevented from being contaminated by contact with different materials, and the surface state can be kept constant.

The lower layer constituting the absorption layer together with the surface layer may be a single layer or a plurality of layers of two or more layers, but a single layer is particularly preferable. That is, when the absorption layer has a two-layer structure of the lower layer of the single layer and the surface layer thereon, the structure can be simplified as much as possible to improve the productivity of the solvent absorber.
The lower layer is formed of silicone rubber or the like. In particular , it is preferably formed of the same kind of silicone rubber as the surface layer. Thereby, the adhesiveness between the two layers can be enhanced, and the solvent absorbed from the silicone blanket can be moved as smoothly as possible from the surface layer to the lower layer. Moreover, when the solvent absorber is curved by following the surface of the silicone blanket for absorbing the solvent, it is possible to make it difficult to cause peeling between the two layers.

  Also, the surface layer is preferably formed by applying a liquid or pasty silicone rubber or the like when uncured onto the lower layer formed on the base material, followed by a curing reaction. When formed of rubber or the like, the liquid silicone rubber or the like can be applied as uniformly as possible on the lower layer without entraining bubbles or causing repelling.

Further, it is possible to prevent the curing reaction of silicone rubber or the like after application from being inhibited by different materials. Therefore, a good surface layer excellent in surface smoothness and strength can be formed on the lower layer.
In order to make the swelling rate of the solvent in the lower layer made of the silicone rubber or the like higher than the surface layer, for example, the silicone rubber that contributes to the swelling has a different degree of crosslinking between the two layers, or the silicone rubber or the like that forms the two layers. What is necessary is just to select and combine the thing from which the said swelling rate differs.

The swelling rate of the surface layer and the lower layer is not particularly limited, but the swelling rate of the surface layer is preferably 4% or more, particularly 6%, preferably less than 12%, particularly preferably 10% or less.
If the swelling rate of the surface layer is less than the above range, the ability to absorb the solvent in the surface layer itself is insufficient, and there is a possibility that the solvent can be smoothly absorbed and removed from the surface of the silicone blanket in a short time. For this reason, the time required for the solvent absorption process becomes long, and the effect of shortening the tact time of printing may be insufficient.

  On the other hand, when the swelling rate of the surface layer exceeds the above range, the ability to absorb the solvent in the surface layer itself is too high, and the surface of the silicone blanket is gradually in a state of insufficient solvent while repeating the solvent absorption process. There is a risk of becoming. For this reason, the acceptability of ink from the intaglio to the surface of the silicone blanket is gradually lowered, and the line width of the fine line pattern may gradually become narrower or disconnection may occur.

Further, the swelling ratio of the lower layer may be higher than the swelling ratio of the surface layer, but is preferably 12% or more, particularly preferably 14% or more, and is preferably 18% or less, particularly preferably 16% or less.
If the swelling rate of the lower layer is less than the above range, the difference from the swelling rate of the surface layer becomes small depending on the swelling rate of the surface layer to be combined, and the solvent impregnated in the surface layer is smoothly applied to the lower layer based on the difference in swelling rate. May not be able to move. For this reason, maintaining the surface of the surface layer for a relatively long time in a state where the amount of impregnation of the solvent is small and absorbs the solvent for a relatively long time, the effect of shortening the tact time of printing by reducing the frequency of replacement and solvent removal operations is ineffective. May be sufficient.

In addition, a lower layer having a higher swelling ratio that exceeds the above range has insufficient strength and needs to be frequently replaced, and the effect of shortening the tact time of printing may be insufficient.
Further, the difference in swelling ratio between the surface layer and the lower layer is preferably 3 points or more, particularly preferably 5 points or more, and preferably 11 points or less, particularly 9 points or less.
If the difference in swelling rate is less than the above range, the difference in swelling rate between the two layers becomes small, and the solvent impregnated in the surface layer may not be smoothly transferred to the lower layer based on the difference in swelling rate. For this reason, maintaining the surface of the surface layer for a relatively long time in a state where the amount of impregnation of the solvent is small and absorbs the solvent for a relatively long time, the effect of shortening the tact time of printing by reducing the frequency of replacement and solvent removal operations is ineffective. May be sufficient.

In addition, when trying to combine the surface layer and the lower layer exceeding the range, the swelling rate of the surface layer is less than the preferred range, or the swelling rate of the lower layer exceeds the preferred range. However, the effect of shortening the printing tact time may be insufficient.
The silicone rubber or the like constituting the surface layer and the lower layer is preferably a liquid or paste when uncured as described above.

  The lower layer can be formed by applying the liquid or paste-like silicone rubber or the like on the base material so as to have a predetermined thickness using, for example, a doctor knife, a bar coater, a roll coater or the like, and then curing it. At that time, the surface of the lower layer, that is, the surface of the lower layer after curing, can be smoothed and the thickness of the lower layer can be made uniform by a so-called self-leveling effect.

  The surface layer can be formed by applying the liquid or paste-like silicone rubber or the like on the lower layer so as to have a predetermined thickness using a doctor knife, bar coater, roll coater or the like. . At that time, the surface of the coating layer that becomes 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 by the self-leveling effect.

Therefore, it is possible to produce a solvent absorber excellent in surface smoothness with good productivity without passing through a step such as polishing, which can adhere to the surface of the silicone blanket without gaps and absorb the solvent. Needless to say, the surfaces of the lower layer and the surface layer may be polished as necessary.
The lower layer may be formed by injecting and curing the liquid rubber or paste-like silicone rubber or the like into a mold having a shaping surface corresponding to the surface shape and setting the base material. . Similarly, the surface layer is formed by injecting and curing the liquid rubber or paste-like silicone rubber or the like into a mold having a shaping surface corresponding to the surface shape and setting the base material on which the lower layer is formed. It may be formed.

  The silicone rubber or the like is preferably room temperature curable (RTV). The room temperature curable silicone rubber can be cured at room temperature (5-35 ° C) without heating as its name suggests, so the manufacturing process and manufacturing equipment for the solvent absorber are simplified. In addition, since it does not undergo expansion due to heating and shrinkage during cooling, the accuracy of the thickness of the lower layer, the surface layer, and the absorption layer, which is a laminate of both layers, can be improved.

The silicone rubber or the like is preferably a two-component addition reaction type that consists of two components of a main agent and a curing agent as described above and can cure both of them by an addition reaction.
The two-component addition reaction type silicone rubber or the like does not generate a by-product (water by dehydration condensation reaction) during the curing reaction, so that the dimensional accuracy of the lower layer and the surface layer is improved, and bubbles and the like based on the by-product are removed. A uniform lower layer or surface layer not included can be formed.

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

It is preferable that the total thickness of the absorption layer having a two-layer structure including the surface layer and the lower layer, or the absorption layer having a multilayer structure of three or more layers is 0.01 mm or more and 1 mm or less.
Since a thin absorbent layer with a thickness less than the above range cannot absorb a sufficient amount of solvent, printing is performed less frequently by replacing the solvent absorber or removing the solvent by heating or the like. The effect of shortening the tact time may be insufficient.

Further, when the above range is exceeded, the flexibility of the solvent absorber as a whole and the followability to the surface of the silicone blanket are reduced, and it is used under the condition that it is wound around the outer periphery of the blanket cylinder, for example. There is a possibility that the solvent cannot be absorbed with the surface of the silicone blanket in contact with the absorbent layer as close as possible.
In addition, the weight of the absorbent layer increases, so that the handleability when contacting the surface of the silicone blanket as described above may be reduced, and the substrate may be easily broken or wrinkled during the handling.

When the absorption layer is formed of two layers, a surface layer and a lower layer, the thicknesses of the two layers can be arbitrarily set. In particular, the lower layer thickness T _U is set to be equal to or greater than the surface layer thickness T _S (T _U ≧ T _S ). It is preferable to do this. As a result, more solvent can be absorbed in the lower layer, and the surface of the surface layer can be maintained as long as possible in a state where the amount of impregnation of the solvent is small and the solvent is easily absorbed. Further, the solvent absorbed from the surface of the silicone blanket can be passed through the surface layer smoothly to impregnate the lower layer.

  However, when the thickness of the surface layer is too small, when the surface of the surface layer is brought into contact with the surface of the silicone blanket in the solvent absorption step, the solvent impregnated in the lower layer is returned to the surface of the surface layer due to the contact pressure or the like. Thus, there is a risk that solvent absorption from the silicone blanket may be hindered, and conversely, the amount of solvent impregnation in the silicone blanket may be increased. Therefore, the thickness of the surface layer is preferably 0.005 mm or more, and particularly preferably 0.008 mm or more.

The total hardness of the absorbent layer is preferably equal to or less than the hardness of the surface of the silicone blanket, considering that the surface of the silicone blanket is satisfactorily followed and contacted without gaps.
In order to reduce the overall hardness of the absorbent layer to less than the hardness of the surface of the silicone blanket, for example, the silicone blanket that is the basis of each layer constituting the absorbent layer, the hardness after curing is the silicone blanket. What is necessary is just to select and use what is equivalent to or less than the hardness of the surface. Thereby, the whole hardness of an absorption layer can be made softer than the surface of a silicone blanket.

  The specific range of the hardness of each layer that is the basis of the absorbent layer is not particularly limited as long as it is equal to or less than the hardness of the surface of the silicone blanket as described above. For example, Japanese Industrial Standard JIS K6253: 2006 It is A5 / S or more and A50 / S or less, particularly A10 / S or more and A30 / S or less in terms of the type A durometer hardness defined in “Sulfur Rubber and Thermoplastic Rubber—How to Obtain Hardness”. preferable.

Further, the surface of the absorbent layer is preferably as smooth as possible in order to adhere to the surface of the silicone blanket without any gap. However, since the absorption layer is flexible as described above, even if the surface of the silicone blanket is not as flat, it can be adhered to the surface without sufficient gaps.
Although the specific range of the surface roughness of the surface is not particularly limited, Japanese Industrial Standard JIS B0601: 2001 “Product Geometrical Specification (GPS) —Surface Properties: Contour Curve Method—Terms, Definitions, and Surface Property Parameters” It is preferably 0.01 μm or more and 5 μm or less, particularly 0.05 μm or more and 1 μm or less in terms of ten-point average roughness Rz _JIS94 defined in Appendix 1 of the above.

In the case where the layer below the surface layer is a plurality of layers of two or more layers, in order to make the solvent transfer mechanism described above function as smoothly and satisfactorily as possible, at least the surface layer of the plurality of layers is directly below the surface layer. It is preferable to dispose a layer having a higher swelling ratio of the solvent.
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.
The thickness of the substrate is preferably 0.05 mm or more, particularly 0.1 mm or more, preferably 0.35 mm or less, particularly preferably 0.25 mm or less.

If the thickness is less than the above range, the base material does not sufficiently obtain the effect of maintaining the strength of the entire solvent absorber as a support for the absorbent layer and ensuring good handling properties, and the base material breaks during handling. There is also a risk of getting wrinkled.
Also, if the thickness exceeds the above range, the flexibility of the solvent absorber as a whole and the followability to the surface of the silicone blanket are reduced, such as being wound around the outer periphery of the blanket cylinder, etc. There is a possibility that the solvent cannot be absorbed with the surface of the silicone blanket used being in contact with the absorbent layer with as little gap as possible.

In order to improve the adhesion of the absorbing layer, the surface of the base material before forming the absorbing layer may be subjected to pretreatment such as plasma treatment or flame treatment, or an arbitrary underlayer may be formed. Good.
The absorption layer may be formed on one side of the substrate or on both sides. In the solvent absorber in which the absorption layers are formed on both sides, the absorption layer on one side can be used for absorbing the solvent, and then the absorption layer on the opposite side can be used for absorbing the solvent.

The solvent absorber can be formed into an arbitrary shape according to the structure of a printing machine that performs the printing method, and is particularly preferably formed into a belt shape (including an endless belt shape). Accordingly, the present invention can be applied as it is to a conventional offset printing machine using the belt-like solvent absorber.
For example, an operation of absorbing the solvent by forming a solvent absorber in the form of a long belt and winding it into a roll, and bringing a predetermined length region of the solvent absorber fed from the roll into contact with the surface of the silicone blanket. The same region can be used once or several times, and each time the predetermined operation is performed, a new region of the solvent absorber can be fed out from the roll and used for solvent absorption in the same manner.

In addition, the solvent absorber is formed in an endless belt shape, and the solvent absorber is heated every time one or several times when the solvent absorber is rotated and brought into contact with the surface of the silicone blanket to absorb the solvent. The solvent absorber can be repeatedly used for solvent absorption while removing the absorbed solvent.
Moreover, in any of these cases, the absorption layer of the solvent absorber has a laminated structure of the surface layer and a layer having a higher solvent swelling rate than the surface layer as described above. The surface of a certain surface layer can be maintained for a relatively long time in a state where the amount of impregnation of the solvent is low and the solvent is easily absorbed, and the frequency of replacement and solvent removal operations is reduced compared to the conventional method, and the tact time of printing is reduced. It becomes possible to improve productivity of a product by shortening.

The solvent absorber 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 using a silicone blanket.

In the various printing methods, the step of absorbing and removing the solvent impregnated in the silicone blanket by the solvent absorber by bringing the solvent absorber into contact with the surface of the silicone blanket between the printing, the solvent It can be carried out using an absorber. This makes it possible to maintain the printing accuracy at a high level over a long period from the initial printing.
As the silicone blanket, various silicone blankets having at least a surface formed of silicone rubber or the like can be used. Specifically, for example, a silicone blanket provided with a film-like or sheet-like substrate and a surface rubber layer formed on one surface of the substrate and made of a composition containing at least silicone rubber or the like is preferable.

  The silicone rubber or the like constituting the surface rubber layer is preferably a liquid silicone rubber or a silicone resin that is liquid or pasty when uncured. The liquid silicone rubber or the like is applied to a base material so as to have a predetermined thickness using, for example, a doctor knife, a bar coater, a roll coater, etc., and is cured to form the surface rubber layer. Thus, the surface of the surface rubber layer can be smoothed and the thickness can be made uniform. For this reason, a silicone blanket having a surface rubber layer with excellent surface smoothness suitable for forming a fine and high-precision pattern on the surface of a substrate as a substrate to be printed has high productivity without undergoing steps such as polishing. Can be manufactured. Needless to say, the surface of the surface rubber layer may be polished as necessary.

The silicone blanket is manufactured by injecting and curing the liquid rubber or paste-like silicone rubber or the like into a mold on which a base material is set, having a shaping surface corresponding to the surface shape of the surface rubber layer. May be.
The silicone rubber or the like is preferably room temperature curable (RTV). The room temperature curing type silicone rubber can be cured at room temperature without heating, so that the manufacturing process and equipment for the silicone blanket can be simplified, and the expansion by heating and the contraction at the time of cooling. Therefore, the accuracy of the thickness of the surface rubber layer can be improved.

The silicone rubber or the like is preferably a two-component addition reaction type comprising two components of a main agent and a curing agent and capable of curing both of them by an addition reaction.
The two-component addition reaction type silicone rubber or the like does not generate a by-product (water or the like by dehydration condensation reaction) during the curing reaction, so that the dimensional accuracy of the surface rubber layer is improved and bubbles or the like based on the by-product It is possible to form a uniform surface rubber layer that does not contain any.

  Examples of the room temperature curable and two-component addition type liquid silicone rubber include the above-mentioned product numbers KE1600, KE1603, KE1606, KE1310ST, KE1300T, KE1314, KE1241, KE106, KE103, manufactured by Shin-Etsu Chemical Co., Ltd. Examples include TSE3402, TSE3453, TSE3455T, TSE3457, and TSE3466 manufactured by Momentive Performance Materials.

The thickness of the surface rubber layer is preferably about 0.01 mm or more and 0.5 mm or less in the case of a silicone blanket for precision printing that requires high printing accuracy such as the PDP and LCD patterns described above. .
Examples of the substrate include various resin films or sheets similar to those used in the solvent absorber described above, and metal thin plates, etc., and in particular a film having an arbitrary thickness and surface roughness or A PET film or sheet that is easily processed into a sheet and has excellent dimensional stability is preferred.

In the case of the precision printing silicone blanket, the thickness of the substrate is preferably about 0.01 mm or more and 0.4 mm or less.
In order to improve the adhesion of the surface rubber layer, the surface of the base material before forming the surface rubber layer may be subjected to pretreatment such as plasma treatment or flame treatment, or an arbitrary underlayer may be formed. May be.

The hardness of the surface rubber layer is not less than A10 / S and not more than A70 / S, particularly not less than A30 / S and not more than A60 / S in terms of the type A durometer hardness defined in JIS K6253: 2006. preferable.
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 precision printing silicone blanket is defined in Appendix 1 of the above-mentioned JIS B0601: 2001 “Product Geometrical Specification (GPS) —Surface Properties: Contour Curve Method—Terminology, Definitions, and Surface Property Parameters”. The ten-point average roughness Rz expressed in _JIS94 is preferably about 0.01 μm or more and 1 μm or less.

Production of the solvent absorbers of the following examples and comparative examples, measurement of characteristics, and tests were performed in an environment of a temperature of 23 ± 1 ° C. and a relative humidity of 55 ± 1%, unless otherwise specified.
<Example 1>
After mixing 100 parts by mass of the main component of a liquid dimethyl silicone rubber (KE1241 manufactured by Koshi Chemical Industry Co., Ltd.), a two-component addition reaction type liquid dimethyl silicone rubber, which is a room temperature curing type, and 10 parts by mass of a curing agent, defoaming and mixing A coating solution was prepared, and the coating solution was applied to one side of a 0.25 mm thick PET film as a substrate using a bar coater, and then allowed to stand at room temperature for 24 hours to be cured. A lower layer in which the dimension in the surface direction of the film was 60 cm long × 50 cm wide was formed.

  Next, after mixing 100 parts by mass of the main component of a liquid dimethyl silicone rubber (KE1603 manufactured by Shin-Etsu Chemical Co., Ltd.), which is a room temperature curing type and a two-component addition reaction type, and defoaming, the surface layer was removed. The coating liquid was prepared on the surface of the lower layer on the PET film using a bar coater and then allowed to stand at room temperature for 24 hours to be cured. A surface layer having a dimension of 60 cm in length and 50 cm in width was formed, and a solvent absorber including an absorption layer having a two-layer structure of the lower layer and the surface layer was manufactured.

In addition, the method which demonstrated the swelling amount of the butyl carbitol acetate as a solvent about the said both samples using the same coating liquid used for formation of the said lower layer and surface layer, and the said both samples. As a result, the swelling amount of the lower layer was 15%, and the swelling amount of the surface layer was 8%.
<Example 2>
A solvent absorber having a two-layer structure of the lower layer and the surface layer was produced in the same manner as in Example 1 except that the thickness of the lower layer was 0.25 mm and the thickness of the surface layer was 0.25 mm.

<Example 3>
A solvent absorber having a two-layer structure of the lower layer and the surface layer was produced in the same manner as in Example 1 except that the thickness of the lower layer was 0.1 mm and the thickness of the surface layer was 0.4 mm.
<Comparative example 1>
The same surface layer coating solution as prepared in Example 1 was applied to one side of a 0.25 mm-thick PET film as a base material using a bar coater, and then allowed to stand at room temperature for 24 hours to be cured. A solvent absorber provided with an absorption layer having a single-layer structure of 0.5 mm and a PET film having a dimension in the plane direction of 60 cm in length and 50 cm in width was manufactured.

<Comparative example 2>
The same coating solution for the surface layer as prepared in Example 1 was applied to one side of a PET film having a thickness of 0.25 mm as a base material using a bar coater, and then allowed to stand at room temperature for 24 hours to be cured. A lower layer having a size of 0.25 mm and a PET film in the surface direction of 60 cm long × 50 cm wide was formed.

Next, the same coating solution for the lower layer as prepared in Example 1 was applied to the surface of the lower layer on the PET film using a bar coater, and then allowed to stand at room temperature for 24 hours to be cured, with a thickness of 0.25 mm, A surface layer in which the dimension of the surface direction of the PET film was 60 cm long × 50 cm wide was formed, and a solvent absorber provided with an absorbing layer having a two-layer structure of the lower layer and the surface layer was produced.
<Printing characteristic test>
(Production of silicone bracket)
91 parts by mass of main agent and 9 parts by mass of curing agent which are room temperature curing type and two-component addition reaction type liquid silicone rubber (type A durometer hardness after curing (according to JIS K6253: 2006) is A30 / S) And then defoaming to prepare a coating solution for the surface rubber layer. The coating solution was applied to one side of a 0.25 mm thick PET film as a substrate using a bar coater, and then at room temperature for 24 hours. It was allowed to stand and cured to form a rubber blanket by forming a surface rubber layer having a thickness of 0.70 mm and a dimension in the plane direction of the PET film of 60 cm long × 50 cm wide.

(Printing process)
The silicone blanket was wound around and fixed to the outer periphery of a blanket cylinder of an intaglio offset printing machine (manufactured by Nakan Co., Ltd., a flat plate precision printing machine compatible with 360 mm × 460 mm). Further, as the intaglio, a glass plate was used in which concave portions having a line width of 20 μm, a pitch of 300 μm and a depth of 8 μm were formed in a lattice pattern on the surface of the glass plate.

The ink used was prepared by kneading polyester resin, butyl carbitol acetate as a solvent, and silver powder using three rolls.
Further, any solvent absorber manufactured in each of the above examples and comparative examples is joined to each other while being rotated in synchronization with a silicone blanket wound around the outer periphery of the blanket cylinder by joining both ends into an endless belt shape. It was set so that the absorption process could be carried out. The feed speed of the endless belt during synchronous rotation was set to 40 mm / s. The solvent absorption step was performed every time printing was performed.

The printing conditions are set such that the ink transfer speed from the intaglio to the silicone blanket is set to 100 mm / s, the ink transfer speed from the silicone blanket to the surface of the glass substrate as the printing body is set to 100 mm / s, and the glass Continuous printing was performed while replacing the substrate.
Then, by observing the pattern printed on the surface of the glass substrate, it is printed until the line width of the pattern gradually increases to exceed 25 μm, or conversely decreases to less than 15 μm, or disconnection occurs. The number of printed sheets was counted.

  The results are shown in Table 1.

  In the case of using the conventional solvent absorber of Comparative Example 1 having an absorption layer having a single-layer structure, the absorption layer swells with the solvent while repeating the solvent absorption step, and the solvent becomes difficult to absorb, Along with this, the wettability of the surface of the silicone blanket gradually increases and the ink easily spreads, and the line width of the fine line pattern gradually increases, and the line width exceeds 25 μm when the number of printed sheets is 400 sheets. I gave up printing.

  In the case of using the solvent absorber of Comparative Example 2 in which the absorbent layer has a two-layer structure consisting of a lower layer and a surface layer having a higher swelling rate than the lower layer, contrary to the present invention, the solvent absorption step is repeated. In addition, the surface of the silicone blanket gradually became solvent-deficient, and the acceptability of the ink from the intaglio to the surface of the silicone blanket was gradually lowered, resulting in disconnection of the fine line pattern with 100 printed sheets. Abandoned.

  On the other hand, when the solvent absorbers of Examples 1 to 3 having a surface layer and a lower layer having a higher swelling rate than the surface layer were used, the surface of the surface layer was determined by the function of the lower layer. Can be maintained in a state where the amount of impregnation of the solvent is small and the solvent is easily absorbed, and accordingly, the amount of the solvent on the surface of the silicone blanket can be maintained in an appropriate range, so that the line width is 25 μm over 500 printed sheets. It has been found that good fine line patterns that do not exceed, conversely, fall below 15 μm, or cause disconnection can be continuously printed. Further, from the results of each example, by setting the thickness of the lower layer to be equal to or greater than the thickness of the surface layer, the function of the lower layer is exhibited more satisfactorily, and a good fine line pattern is continuously printed as described above. It has also been found that the number of times it can be continued can be increased.

Claims (2)

A film-like or sheet-like base material, and an absorbing layer formed on at least one side of the base material, the solvent contained in the ink used for the printing method using a silicone blanket and impregnated in the silicone blanket, A solvent absorber for absorbing and removing the absorbent layer by bringing the absorbent layer into contact with the surface of the silicone blanket, wherein the absorbent layer is made of silicone rubber or silicone resin, and the surface is Consists of a laminated structure of two or more layers including a surface layer that does not contain bubbles , and is made of silicone rubber or silicone resin on the substrate side from the surface layer , and includes bubbles that have a higher swelling rate of the solvent than the surface layer. solvent absorber characterized by being arranged with no layers.   The solvent absorber according to claim 1, wherein the absorption layer has a two-layer structure of the surface layer and a lower layer having a higher solvent swelling ratio than the surface layer.