JP2011118346A - Ink, reverse printing method, liquid crystal color filter, and process for manufacturing the liquid crystal color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for a reverse printing method compatibly having moderate wettability and mold-release properties with respect to the surface of a silicone blanket and hardly causing a problem of safety, vertical streak, unevenness and the like, to provide a reverse printing method using the same, to provide a liquid crystal color filter provided with a color filter layer free from unevenness, a pinhole and the like, and a black matrix layer, and to provide a process for manufacturing the same. <P>SOLUTION: In the ink comprising a binder resin, a colorant, and a solvent, the solvent contains 5 to 50 mass% fluorine solvent having 50 to 150°C boiling point and 12 to 18 mN/m surface tension at 25°C. In the reverse printing method, the ink is used. In the liquid crystal color filter 22, the color filter layer 25 and/or the black matrix layer 24 is formed by the reverse printing method. The process for manufacturing the liquid crystal color filter includes a step of forming the color filter layer 25 and/or the black matrix layer 24 by the reverse printing method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink used in a so-called reverse printing method, a reverse printing method using the ink, a liquid crystal color filter constituting a liquid crystal display (LCD), and a method for manufacturing the liquid crystal color filter.

The liquid crystal color filter or the like is manufactured by forming a very fine ink pattern compared to the area of the substrate, such as the color filter layer or the black matrix layer of the liquid crystal color filter constituting the LCD, on almost the entire surface of the substrate. Therefore, conventionally, a forming method using a so-called photolithography method has been adopted.
Recently, however, the printing method, particularly intaglio offset printing, is used in order to reduce the number of processes as much as possible, reduce the energy consumption, reduce the waste of materials used, and form a pattern with high productivity in a short time instead of the photolithographic method. The use of law is becoming widespread.

In the intaglio offset printing method, the ink filled in the concave portion of a plate (intaglio) having a concave portion corresponding to the ink pattern to be printed is transferred from the plate to the surface of the printing blanket, and then from the surface of the printing blanket. An ink pattern is formed on the surface of the substrate by retransferring it onto the surface of the substrate as the substrate.
However, the ink pattern formed on the surface of the substrate by the intaglio offset printing method tends to have a large variation in thickness. That is, in the intaglio offset printing method, as is apparent from the above-described process, the ink is transferred twice, and at each transfer, the ink is torn into the amount transferred to the transfer destination and the amount remaining at the transfer source. Since the ink is separated, the ink pattern that is finally transferred onto the surface of the substrate tends to have unevenness with a large difference in height as the separation trace, resulting in a large thickness variation.

Therefore, as a new printing method that replaces the intaglio offset printing method, in particular, to form liquid crystal color filters that are required to be as uniform as possible in order to make the color density uniform within each pixel and between each pixel. A reversal printing method has been developed (see Patent Documents 1-3).
In the reverse printing method, ink is supplied to substantially the entire surface of the printing blanket to form a solid ink layer, and the ink layer is formed on the surface of the plate having concave portions corresponding to a predetermined ink pattern on the surface. The ink layer other than the recesses is contacted and transferred to the surface of the plate to selectively remove it from the surface of the printing blanket, and an ink pattern corresponding to the recesses is formed on the surface of the printing blanket. After the formation, the ink pattern is transferred to the surface of the substrate, whereby an ink pattern is formed on the surface of the substrate.

According to the reverse printing method, the number of times of ink transfer for forming the ink pattern can be reduced to one time at the time of transfer from the surface of the printing blanket to the surface of the substrate, so that compared with the conventional intaglio offset printing method. Thus, the height difference of the unevenness remaining on the surface of the ink pattern can be reduced, and the variation in thickness can be reduced.
As a printing blanket, a silicone blanket having at least a surface formed of silicone rubber is widely used. Since the silicone blanket is excellent in ink releasability, the transferability of the ink pattern from the surface to the surface of the substrate can be improved.

However, since the surface of the silicone blanket has low ink wettability, it is likely to cause repellence when the ink is formed on the substantially entire surface of the silicone blanket at the beginning of the process. There is a problem that it is impossible to form an ink layer having a uniform thickness without unevenness or pinholes.
Therefore, as an ink for the reverse printing method, in order to obtain an ink having appropriate wettability and releasability to the surface of the silicone blanket, the surface tension of the ink, the boiling point of the solvent contained in the ink, the silicone of the ink It has been studied to adjust the swelling ratio with respect to rubber (see Patent Document 4).

JP-A-11-58921 JP-A-11-198337 JP 2000-289320 A JP 2006-111725 A

In order to adjust the surface tension of the ink, a solvent having a low surface tension (hereinafter sometimes referred to as “low tension solvent”) may be used alone or in combination with other solvents. Is called.
However, general low-tension solvents have low polarity and low solubility in high-polar binder resins used in inks, so the low-strength solvents are used alone or in high concentrations in combination with other solvents. When it is contained, the binder resin cannot be dissolved satisfactorily, and the solid content of the binder resin or the like tends to precipitate as foreign matter in the ink.

And, due to the deposited foreign matter, there is a problem that the solid ink layer formed on the surface of the silicone blanket is likely to have vertical stripes, or the shape of the ink pattern is likely to be disturbed due to the vertical stripes. is there.
That is, in the reverse printing method, for example, a slit having a width corresponding to the width of the ink layer to be formed and an interval corresponding to the thickness in order to form a solid ink layer by supplying ink to substantially the entire surface of the silicone blanket. It is common to use a slit die coater equipped with

While the silicone blanket is rotated at a constant speed, a predetermined amount of ink is continuously supplied to the surface through the slit of the slit die coater, so that a solid having a width and thickness corresponding to the width and interval of the slit is obtained. The ink layer is formed on the surface of the silicone blanket.
However, when foreign matter is deposited in the ink as described above, the foreign matter partially blocks the slit, and as a result, the supply of ink is blocked by a part of the slit in the width direction. A vertical streak is formed at a position corresponding to a portion blocked by the foreign matter in the width direction of the ink layer. In addition, the shape of the ink pattern is disturbed based on variations in the thickness of the ink layer due to vertical stripes.

In addition, many of the low-tension solvents have a low boiling point or a low flash point as exemplified in Patent Document 4, for example, causing problems in terms of safety when they are contained in ink. There is also a fear.
In addition, since low-tension solvents with low boiling points tend to volatilize out of the ink, for example, vertical stripes and unevenness occur when forming an ink layer using the slit die coater or the like, and the shape of the ink pattern is disturbed by the vertical stripes and unevenness. There is also a problem that it is likely to occur.

  In other words, when using an ink containing a low-tensile solvent with a low boiling point that easily volatilizes, the ink layer is repeatedly formed using the slit die coater or the like even if the foreign matter described above is not deposited during the preparation of the ink. In the meantime, the drying of the ink due to the volatilization of the low-tensile solvent, and the solid content of the binder resin or the like in the ink easily precipitates as agglomeration with the agglomeration. As a result of hindering the supply of ink at a part in the width direction of the slit, a vertical stripe is generated at a position corresponding to the portion blocked by the foreign matter in the width direction of the ink layer formed on the surface of the silicone blanket.

In addition, even if the foreign matter does not precipitate and the vertical streaks associated therewith, the ink layer has unevenness due to an increase in the viscosity of the ink, or the shape of the ink pattern is based on variations in the thickness of the ink layer due to the vertical streaks or unevenness. May be disturbed.
An object of the present invention is an ink for a reversal printing method which has moderate wettability and releasability with respect to the surface of a silicone blanket, and is less likely to cause safety problems, vertical stripes, unevenness, and the like. And a reversal printing method using the same. Another object of the present invention is to provide a liquid crystal color filter having a uniform color filter layer, a black matrix layer, and the like having no unevenness or pinholes, and a manufacturing method thereof.

  In the present invention, an ink layer formed on substantially the entire surface of a silicone blanket is brought into contact with the surface of a plate having a recess corresponding to a predetermined ink pattern on the surface, and an ink layer other than the recess is formed on the surface of the plate. The ink is selectively removed from the surface of the silicone blanket to form an ink pattern corresponding to the recess on the surface of the silicone blanket, and then the ink pattern is printed on the surface of the substrate. An ink for use in a printing method, including a binder resin, a colorant, and a solvent, wherein the solvent has a boiling point of 50 ° C. or higher and 150 ° C. or lower and a surface tension at 25 ° C. of 12 mN / m or higher and 18 mN / m or lower. An ink comprising a solvent in a proportion of 5% by mass to 50% by mass.

In the present invention, the fluorinated solvent used as the low-tension solvent basically has no flash point and is nonflammable. Therefore, it is possible to impart nonflammability to the ink and improve safety.
Further, as the fluorinated solvent, one having a surface tension at 25 ° C. of 12 mN / m or more and 18 mN / m or less is selectively used, and the fluorinated solvent is used in an amount of 5% by mass or more and 50% by mass in the total amount of the solvent. By containing in a range of not more than%, the surface tension of the entire ink can be adjusted, and appropriate wettability and releasability to the surface of the silicone blanket can be imparted to the ink.

Further, as the solvent other than the fluorine-based solvent, a solvent having excellent solubility in the binder resin is used, and as the fluorine-based solvent, a solvent having a boiling point of 50 ° C. or higher and 150 ° C. or lower is selectively used, whereby the vertical streak or unevenness can be obtained. And the accompanying disorder of the shape of the ink pattern can be prevented.
Therefore, according to the present invention, there is provided an ink for a reversal printing method which has moderate wettability and releasability with respect to the surface of the silicone blanket and is less likely to cause safety problems, vertical stripes, unevenness, and the like. It becomes possible to do.

As the fluorine-based solvent, at least one selected from the group consisting of hydrofluoroethers excellent in the above-mentioned various effects and not containing chlorine and hydrofluorocarbons is preferable.
Further, the ink of the present invention preferably further contains a fluorosurfactant in the range of 0.1% by mass or more and 1% by mass or less in the total amount of the ink. By including the fluorosurfactant in the above range, the wettability of the ink to the surface of the silicone blanket can be further improved.

  The present invention uses the ink of the present invention to bring an ink layer formed on substantially the entire surface of a silicone blanket into contact with the surface of a plate having a recess corresponding to a predetermined ink pattern on the surface, thereby The ink layer is transferred onto the surface of the plate by selectively removing it from the surface of the silicone blanket, and after forming an ink pattern corresponding to the recess on the surface of the silicone blanket, the ink pattern A reverse printing method characterized by printing on the surface of a printing medium.

According to the present invention, by using the ink of the present invention, an ink layer having a uniform thickness without unevenness or pinholes can be formed by reverse printing.
Therefore, by employing the reverse printing method, it is possible to obtain a liquid crystal color filter including a color filter layer, a black matrix layer, and the like having a uniform thickness without unevenness or pinholes.

That is, the present invention includes a transparent substrate, a color filter layer formed on the transparent substrate, and a black matrix layer, and at least one of the color filter layer and the black matrix layer is an inversion of the invention. A liquid crystal color filter formed by a printing method.
The present invention also provides a method for producing a liquid crystal color filter, comprising a step of forming at least one of a color filter layer and a black matrix layer on a transparent substrate by the reversal printing method of the present invention. .

  According to the present invention, there is provided ink for reversal printing which has moderate wettability and releasability with respect to the surface of the silicone blanket and is less likely to cause safety problems, vertical stripes, unevenness, and the like. Can be provided. In addition, according to the present invention, it is possible to provide a liquid crystal color filter having a uniform color filter layer, a black matrix layer, and the like with no unevenness or pinholes, and a manufacturing method thereof.

(a)-(c) is the schematic which shows each process in an example of the reverse printing method of this invention. It is sectional drawing which expands and shows a part of example of embodiment of the liquid crystal color filter of this invention.

<ink>
The ink of the present invention is used in a reversal printing method using a silicone blanket as a printing blanket, and includes a binder resin, a colorant, and a solvent, and the solvent has a boiling point of 50 ° C. or higher, 150 ° C. or lower, 25 It is characterized by containing a fluorine-based solvent having a surface tension at 12 ° C. of 12 mN / m or more and 18 mN / m or less in a proportion of 5% by mass or more and 50% by mass or less.

The reason why the boiling point of the fluorinated solvent used in the ink of the present invention at normal pressure (1013.25 hPa) is limited to 50 ° C. or higher and 150 ° C. or lower is as follows.
That is, a fluorinated solvent having a boiling point of less than 50 ° C. is likely to volatilize from the ink, and the ink is dried and agglomerated by the volatilization, which causes foreign matters to precipitate in the ink and cause vertical stripes in the ink layer. Further, even if vertical streaks due to the deposition of the foreign matter do not occur, unevenness of the ink layer due to an increase in ink viscosity occurs, or the shape of the ink pattern is disturbed due to the vertical streaks or unevenness.

  On the other hand, when the boiling point exceeds 150 ° C., it becomes difficult to dry the ink, and it takes a long time to dry after transferring the ink pattern onto the surface of the substrate. In addition, a fluorine-based solvent having a boiling point exceeding 150 ° C. inevitably has a high surface tension due to its chemical structure, so that the effect of lowering the surface tension of the ink becomes insufficient, resulting in unevenness of the ink layer or the unevenness. The ink pattern may be disturbed by the ink pattern.

  In addition, a good ink layer free of vertical stripes and unevenness is formed on the surface of the silicone blanket, and a good ink pattern free of shape irregularities is formed on the surface of the substrate, and the ink pattern is dried as quickly as possible. In consideration of improving the productivity of liquid crystal color filters and the like, the boiling point of the fluorinated solvent is preferably 60 ° C. or higher even in the above range.

The reason why the surface tension of the fluorinated solvent is limited to 12 mN / m or more and 18 mN / m or less at 25 ° C. is as follows.
That is, when the surface tension is less than 12 mN / m, the wettability of the ink with respect to the surface of the silicone blanket becomes too high, depending on the content ratio of the fluorinated solvent or the type of other solvent to be combined, The transfer from the surface of the silicone blanket to the surface of the substrate cannot be satisfactorily performed, and the shape of the transferred ink pattern is disturbed.

Also, the ink wettability with respect to the slit die coater, etc. becomes high, and it becomes easy to adhere particularly near the slit. When the adhered ink dries and the binder resin or the like is deposited as a foreign substance and partially closes the slit, the ink layer Vertical streaks, or the ink pattern shape is disturbed by the vertical streaks.
On the other hand, when the surface tension exceeds 18 mN / m, the effect of reducing the surface tension of the ink and improving the wettability of the ink with respect to the surface of the silicone blanket cannot be obtained. Therefore, when ink is applied to substantially the entire surface of the silicone blanket to form an ink layer, repellence or the like is likely to occur, and the repellency or the like tends to cause unevenness or pinholes in the ink layer.

Considering the formation of a good ink layer without unevenness or pinholes on the surface of the silicone blanket and the formation of a good ink pattern without irregularities in the surface of the substrate, the surface tension of the fluorinated solvent Is preferably 16 mN / m or less even within the above range.
In the present invention, the surface tension of the fluorinated solvent is represented by a value measured by the maximum bubble pressure method using a dynamic surface tension meter Theta t60 manufactured by Eihiro Seiki Co., Ltd. in an environment of 25 ° C. .

As the fluorinated solvent, various fluorinated solvents that contain fluorine atoms in the molecule, are incombustible, and satisfy the ranges of the boiling point and surface tension can be used. Preferably, at least one selected from the group consisting of hydrofluoroethers containing no hydrofluorocarbons and hydrofluorocarbons.
Among the above, the hydrofluoroethers are represented by the formula (1):
X-O-Y (1)
[Wherein, X represents a fluoroalkyl group represented by C _a H _b F _c , and Y represents a fluoroalkyl group represented by C _d H _e F _f . A, b, c, d, e, and f in both formulas are a ≧ 1, b ≧ 0, c ≧ 1, d ≧ 1, e ≧ 1, and f ≧ 0, and b + c = 2a + 1 and e + f = 2d + 1. And when b = 0, a + d> 3 and c + e + f> 8, and when b ≧ 1, an integer satisfying a + d ≧ 3 and b + c + e + f ≧ 8 is shown. ]
The fluorine-containing compound represented by these is mentioned.

The a, b, c, d, e, and f are 9 ≧ a + b> 3 when b = 0, 20 ≧ c + e + f> 8, 8 ≧ a + b ≧ 3 when b ≧ 1, and 18 ≧ b + c + e + f ≧ 8. In particular, it is preferable that 7 ≧ a + b ≧ 5 and 16 ≧ c + e + f ≧ 12 when b = 0, 8 ≧ a + b ≧ 4 and 18 ≧ b + c + e + f ≧ 10 when b ≧ 1.
Among the hydrofluoroethers, those satisfying the conditions of a surface tension of 12 mN / m or more and 18 mN / m or less at a boiling point of 50 ° C. or more and 150 ° C. or less and 25 ° C. include, for example, ethyl nonafluorobutyl ether [boiling point 76 ° C., surface tension 13.6 mN / m], methyl nonafluorobutyl ether [boiling point 76 ° C., surface tension 13.6 mN / m], 1,1,1,2,3,4,4,5,5,5-decafluoro-2- Trifluoromethyl-3-methoxypentane [boiling point 55 ° C., surface tension 14.1 mN / m], 1,1,2,3,3,3-hexafluoropropyl [1-methyl-2,2,3,4, 4,4-hexafluorobutyl] ether [boiling point 79 ° C., surface tension 13.3 mN / m] or the like.

Examples of hydrofluoroethers include NOVEC (registered trademark) HFE-7200 (boiling point 76 ° C., surface tension 13.6 mN / m) manufactured by Sumitomo 3M Limited. The HFE-7200 is a mixture of ethyl nonafluoroisobutyl ether and ethyl nonafluorobutyl ether, both of which are hydrofluoroethers.
Examples of hydrofluorocarbons satisfying the above conditions include 1 such as tridecafluoropentane [boiling point 58 ° C., surface tension 14.1 mN / m], tridecafluorohexane [boiling point 59 ° C., surface tension 12.5 mN / m] and the like. A seed | species or 2 or more types is mentioned.

In order to adjust the boiling point and surface tension of the fluorinated solvent within the above range, a fluorinated solvent having the corresponding boiling point and surface tension is selected, or two or more fluorinated solvents are blended to obtain the boiling point and surface tension. Adjustment may be made so that the tension is within a predetermined range.
The reason why the content ratio of the fluorine-based solvent in the total amount of the solvent is limited to 5% by mass or more and 50% by mass or less is as follows.

  That is, when the content ratio is less than 5% by mass, the effect of reducing the surface tension of the ink and improving the wettability of the ink with respect to the surface of the silicone blanket by containing the fluorine-based solvent cannot be obtained. Therefore, when ink is applied to substantially the entire surface of the silicone blanket to form an ink layer, repellence or the like is likely to occur, and the repellency or the like tends to cause unevenness or pinholes in the ink layer. Further, the effect of imparting nonflammability to the ink cannot be obtained.

On the other hand, when the content exceeds 50% by mass, a binder resin or the like that is not soluble in the fluorine-based solvent is likely to be precipitated as a foreign substance. If the foreign substance partially blocks the slit, a vertical stripe may be generated in the ink layer. The shape of the ink pattern is disturbed by the vertical stripes.
In consideration of forming a good ink pattern free from unevenness, pinholes, shape irregularities and the like on the surface of the substrate, the content of the fluorine-based solvent is preferably 30% by mass or less even within the above range. .

The content ratio is the content ratio of the one kind of fluorinated solvent in the total amount of the solvent when the fluorinated solvent is used alone, and when two or more kinds of fluorinated solvents are used in combination, It is the content ratio of the total amount in the total amount of the solvent.
In consideration of forming a good ink layer free of vertical stripes, unevenness, pinholes, etc. on the surface of the silicone blanket and forming a good ink pattern free of shape irregularities on the surface of the substrate, The content of is preferably 40% by mass or less even within the above range.

Examples of the binder resin include one or more of polyester resin, acrylic resin, ethyl cellulose, polyvinyl butyral, polyester melamine resin, melamine resin, epoxy melamine resin, phenol resin, polyimide resin, epoxy resin, and the like.
In view of improving the durability of a liquid crystal color filter for LCD, etc., a binder resin having a thermosetting property, an ultraviolet curable property, a photocuring property and the like is preferable as the binder resin.

Of these, polyester melamine resin, epoxy melamine resin, and acrylic resin are preferable, and polyester melamine resin is particularly preferable.
The molecular weight of the binder resin is preferably 1000 or more, particularly 5000 or more, preferably 40000 or less, particularly 20000 or less in terms of standard polystyrene equivalent weight average molecular weight Mw by gel permeation chromatography (GPC). . Within the said range, it can set suitably according to the physical property requested | required of ink, such as a viscosity and a thixotropic viscosity.

The amount of the binder resin is also the same, and can be appropriately set according to the physical properties required of the ink, such as viscosity and thixotropic viscosity, but is particularly 3% by mass or more, particularly 5% by mass or more of the total amount of the ink. It is preferably 25% by mass or less, particularly preferably 20% by mass or less.
Examples of the colorant include various pigments and dyes. In particular, in the case of a liquid crystal color filter for LCD, various organic and inorganic pigments are preferable in view of forming an ink pattern excellent in chemical resistance, heat resistance, weather resistance, light resistance and the like.

When the ink is for forming the filter layer of the liquid crystal color filter, examples of the pigment include pigments that match the color of each filter layer of red (R), green (G), and blue (B). .
For example, examples of the red filter layer forming pigment include diketopyrrolopyrrole pigments, quinacridone pigments (eg, dimethylquinacridone, dichloroquinacridone, etc.), anthraquinone pigments, and the like. Examples of the green filter layer forming pigment include halogenated phthalocyanine pigments such as brominated copper phthalocyanine (CI Pigment Green 36) and chlorinated copper phthalocyanine (CI Pigment Green 7). . Furthermore, examples of the blue filter layer forming pigment include phthalocyanine pigments. These pigments can be used alone or in combination of two or more according to the color of each color filter layer.

When the ink is for forming a black matrix layer of a liquid crystal color filter, examples of the pigment include carbon black, titanium black, iron oxide, iron sulfate, chromium oxide, copper oxide, composite oxide (Cr-Co -Fe, Cr-Co-Mn-Fe, Cr-Cu, Cr-Cu-Mn, etc.).
The particle diameter of the pigment can be arbitrarily set in consideration of the thixotropic viscosity of the ink, the smoothness of the pattern surface after printing, etc., but the average particle diameter is preferably 1 nm or more and 100 nm or less.

Pigments having an average particle size of 1 nm or less are difficult to obtain and the cohesiveness becomes extremely high, so that the dispersibility in the ink may be lowered. A pigment exceeding 100 μm may not only reduce the smoothness of the pattern surface, but may also cause clogging in a slit die coater or the like when used in the reverse printing method.
The amount of the colorant such as a pigment can be appropriately set according to the use of the ink, specifically the color density and printability required for the ink.

Examples of other solvents used in combination with the fluorine-based solvent include various solvents that can dissolve the binder resin well to prevent precipitation.
Examples of the other solvent include ethylene glycol monomethyl ether (also known as “methyl cellosolve” and “2-methoxyethanol”), ethylene glycol monoethyl ether (also known as “cellosolve” and “2-ethoxyethanol”), propylene glycol monomethyl ether acetate ( One or two or more types such as “alias“ 1-methoxy-2-propyl acetate ”, hereinafter sometimes abbreviated as“ PGMEA ”), ethylene glycol monobutyl ether (also called“ butyl cellosolve ”, 2-butoxyethanol) It is done. PGMEA is particularly preferable.

The content ratio of the other solvent in the total amount of the solvent is the remainder of the fluorinated solvent, that is, 50% by mass or more and 95% by mass or less.
When the other solvent is used alone, the content is the content of the one other solvent in the total amount of the solvent. When two or more other solvents are used in combination, It is the content ratio of the total amount in the total amount of the solvent.

In addition, the content ratio of all the solvents including the other solvent and the fluorinated solvent in the total amount of ink depends on, for example, the type and molecular weight of the binder resin, the content ratio, the type and content ratio of the colorant, and the like. The ink can be arbitrarily set to have a viscosity suitable for the reverse printing method.
In consideration of further improving the wettability of the ink to the surface of the silicone blanket, the ink preferably further contains a fluorine-based surfactant in addition to the above-described components.

The content of the fluorosurfactant is preferably 0.1% by mass or more and 1% by mass or less in the total amount of ink.
When the content ratio is less than the above range, the above-described effect due to the inclusion of the fluorosurfactant may not be sufficiently obtained. Moreover, even if it exceeds the said range, there exists a possibility that the effect beyond it may not be acquired.

The ink may further contain various additives such as a pigment dispersant, a leveling agent, a thixotropic viscosity imparting agent, and an antifoaming agent in an arbitrary ratio.
The ink can be prepared by blending the above components at a predetermined ratio and kneading them using a three-roll, ball mill, bead mill, attritor, sand mill or the like.
As described above, the ink of the present invention is used in the reversal printing method using a silicone blanket to efficiently produce a liquid crystal color filter for LCD, for example, without causing the various problems described above. Suitable for

In this case, considering that the printing accuracy is improved, the swelling ratio ΔV (%) of the silicone blanket with ink is preferably 5% or more, particularly preferably 10% or more, and is preferably 100% or less, particularly 50% or less. It is preferably 30% or less.
The swelling rate ΔV (%) was determined by immersing a sample of a silicone rubber forming a silicone blanket in an ink set at 23 ± 1 ° C. for 24 hours, and then swelling the volume V ₁ before immersion and after immersion. volume _{V 2} Tokara formula (i):
ΔV (%) = [(V ₂ −V ₁ ) / V ₁ ] × 100 (i)
Can be obtained.

If the swelling ratio ΔV (%) is less than the above range, the ink is likely to be repelled on the surface of the silicone blanket and a uniform ink film may not be formed. When the above range is exceeded, the solvent in the ink is rapidly absorbed by the silicone blanket, so the ink may be dried too quickly.
The swelling ratio ΔV (%) can be adjusted as appropriate by changing the type, combination and amount ratio of the solvents.

<Reversal printing method>
FIGS. 1A to 1C are diagrams for explaining an example of the reverse printing method of the present invention.
First, as shown in FIG. 1 (a), in the coating process, the ink 11 is formed by coating the ink 11 over substantially the entire surface of the silicone blanket 10.
Examples of the silicone blanket 10 include a blanket whose surface is made of silicone rubber.

Examples of the silicone blanket 10 include a single layer of silicone rubber, a layered structure in which a layer of silicone rubber is laminated on one side of a base material made of polyethylene terephthalate (PET) film, metal foil, or the like. Is mentioned.
Of these, the silicone blanket 10 made entirely of a single layer of silicone rubber can be formed, for example, by coating a liquid silicone rubber on a flat plate, causing a cross-linking reaction, and then peeling off the flat plate.

In addition, the silicone blanket 10 having a laminated structure is formed by, for example, injecting a liquid silicone rubber into the mold to cause a crosslinking reaction in a state where the substrate is mounted in the mold, or a liquid silicone rubber on the surface of the substrate. It can be formed by coating and crosslinking reaction.
In the example shown in the figure, the silicone blanket 10 is wound around a cylindrical body 13 so as to have a cylindrical shape that can rotate together with the body 13.

In order to apply the ink 11 to the surface of the silicone blanket 10, a slit die coater 14 is used in the example. The slit die coater 14 includes an ink supply unit 15 to which the ink 11 is supplied and a slit nozzle 16 communicated with the ink supply unit 15.
The slit nozzle 16 is disposed to face the surface of the silicone blanket 10 with a gap in the coating process.

  The slit nozzle 16 is opened in an elongated rectangular shape along the axial direction of the silicone blanket 10 wound in a cylindrical shape. The opening width (lateral opening width) of the slit nozzle 16 along the axial direction is set to be substantially the same as the length of the silicone blanket 10 in the same direction. The opening width (vertical opening width) of the slit nozzle 16 along the direction orthogonal to the axial direction (the circumferential direction of the silicone blanket) is set to, for example, about 3 to 1000 μm, preferably about 30 to 50 μm.

Moreover, the space | interval of the surface of the silicone blanket 10 which opposes, and the front-end | tip of the slit nozzle 16 is set, for example to about 10-150 micrometers, especially about 30-100 micrometers.
The ink 11 of the present invention is supplied to the ink supply unit 15, and the ink 11 is continuously supplied from the tip of the slit nozzle 16 while rotating the silicone blanket 10 in one direction at a constant speed as indicated by an arrow in the figure. Then, the ink layer 12 is formed on substantially the entire surface of the silicone blanket 10.

The thickness of the ink layer 12 is appropriately adjusted by changing the rotational speed of the silicone blanket 10, the viscosity of the ink 11, the vertical opening width of the slit nozzle 16, and the interval between the surface of the silicone blanket 10 and the tip of the slit nozzle 16. it can.
Next, as shown in FIG. 1 (b), in the removing step, the silicone blanket 10 is rolled on the plate 17, and the ink layer 12 is selectively brought into contact with the convex portion 18 of the plate 17, whereby the ink The portion of the ink 11 in contact with the convex portion 18 in the layer 12 is transferred to the convex portion 18 and removed from the surface of the silicone blanket 10. Thereby, an ink pattern 20 corresponding to the shape of the concave portion 19 between the convex portions 18 is formed on the surface of the silicone blanket 10.

The plate 17 is made of a metal such as an iron-nickel alloy (42 alloy, etc.), stainless steel, soda glass, non-alkali glass, etc., on one side by the photolithographic method as described above, What formed the recessed part 19 corresponding to the shape of the ink pattern 20 to print can be used.
Further, in order to improve the durability of the plate 17, the surface of the convex portion 18 may be subjected to, for example, hard chrome plating.

Next, as shown in FIG. 1C, in the printing process, when the silicone blanket 10 is rolled on the substrate 21 to transfer the ink pattern 20 from the surface of the silicone blanket 10 to the surface of the substrate 21, An ink pattern 20 corresponding to the shape of the concave portion 19 of the plate 17 is formed on the surface of the substrate 21, and a series of printing operations is completed.
Thereafter, the ink pattern 20 is dried, and further the binder resin is cured as necessary, whereby the color filter layer, the black matrix layer, and the like constituting the liquid crystal color filter of the LCD described above can be formed.

<Liquid crystal color filter and manufacturing method thereof>
FIG. 2 is an enlarged sectional view showing a part of an example of the embodiment of the liquid crystal color filter of the present invention.
Referring to FIG. 2, the liquid crystal color filter 22 of this example includes a transparent substrate 23, a black matrix layer 24 disposed in parallel with a space on one surface of the transparent substrate 23, and the transparent substrate 23. And a color filter layer 25 covering the substrate 23 and the black matrix layer 24.

The color filter layer 25 has a red color filter layer 23R, a green color filter layer 23G, and a blue color filter layer 23B arranged on the surface in parallel along the longitudinal direction of the black matrix layer 24. Are repeatedly arranged in this order.
Examples of the transparent substrate 23 include a substrate having a high transmittance with respect to light having a wavelength of 400 to 700 nm. Examples of the transparent substrate 23 include glass plates such as non-alkali glass, soda lime glass, and low alkali glass, and plastic plates such as polyether, polysulfone, polyarylate, and polyacrylate.

The black matrix layer 24 functions to prevent color mixing between the color filter layers 25R, 25G, and 25B of different colors and to improve the contrast of the liquid crystal color filter 22.
The black matrix layer 24 is not limited to a stripe shape, and may be formed in a lattice shape. The color filter layer 25 is not limited to a stripe shape, and may be a dot shape filling the lattice.

  When the liquid crystal color filter 22 is manufactured by the manufacturing method of the present invention, the black matrix layer 24 is first formed on the surface of one side of the transparent substrate 23 by the reverse printing method of the present invention described above, and then The color filter layers 25R, 25G, and 25B of the respective colors may be formed sequentially (in no particular order) by the reversal printing method of the present invention so as to cover the transparent substrate 23 and the black matrix layer 24.

The drying reaction of the ink after printing and the curing reaction by heating may be performed individually for each layer, or the curing reaction by heating may be performed only once at the end.
In the manufacturing method of the present invention, only the black matrix layer 24 or only the color filter layer 25 may be formed by the reverse printing method of the present invention, and the other layers may be formed by other forming methods. Examples of the other forming method include the photolithographic method and the intaglio offset printing method described above.

In the following examples and comparative examples, ink preparation and tests were carried out in an environment at a temperature of 23 ± 1 ° C. and a relative humidity of 55 ± 1%, unless otherwise specified.
<Example 1>
100 parts by mass of a polyester melamine resin [weight average molecular weight Mw = 10000] as a binder resin, 20 parts by mass of a colorant, 100 parts by mass of a fluorinated solvent, 300 parts by mass of PGMEA as another solvent, 5 parts by mass of a fluorinated surfactant, And 5 parts by mass of a pigment dispersant were mixed using a planetary mixer, and then kneaded using a bead mill to prepare an ink.

As the colorant, a red pigment (anthraquinone pigment), a green pigment (brominated phthalocyanine), or a blue pigment (copper phthalocyanine) each having a primary particle diameter of 1 to 100 nm is used. An ink was prepared.
As the fluorine-based solvent, a mixture of ethyl nonafluoroisobutyl ether and ethyl nonafluorobutyl ether, both of which are hydrofluoroethers [NOVEC (registered trademark) HFE-7200, manufactured by Sumitomo 3M Ltd., boiling point: 76 ° C., 25 ° C. Surface tension 13.6 mN / m] was used.

As the fluorosurfactant, Surflon (registered trademark) S-611 manufactured by AGC Seimi Chemical Co., Ltd. was used.
Furthermore, as the pigment dispersant, a mixture in which Solsperse (registered trademark) 5000 (pigment derivative type) manufactured by Lubrisol and Solsperse 24000GR (SC) manufactured by the company was blended at a mass ratio of 1: 1 was used.

The content ratio of the fluorinated solvent in the total amount of the solvent in the ink was 25% by mass. Further, the content of the fluorosurfactant in the total amount of ink was 0.94% by mass.
<Examples 2 to 5, Comparative Examples 1 and 2>
By adjusting the amount of the fluorinated solvent and the other solvent, the content ratio of the fluorinated solvent in the total amount of the solvent is 4 mass% (Comparative Example 1), 5 mass% (Example 2), 10 mass%. An ink was prepared in the same manner as in Example 1 except that (Example 3), 30% by mass (Example 4), 50% by mass (Example 5), and 52% by mass (Comparative Example 2) were used. The total amount of the fluorinated solvent and other solvents was 400 parts by mass, the same as in Example 1. The content of the fluorosurfactant in the total amount of ink was 0.94% by mass.

<Examples 6 to 8, Comparative Examples 3 and 4>
Ethyl nonafluorobutyl ether (boiling point: 76 ° C., surface tension: 13.6 mN / m) was used as the fluorinated solvent, and the content of the fluorinated solvent in the total amount of the solvent was 0.5% by mass (Comparative Example 3). Ink in the same manner as in Example 1 except that 5% by mass (Example 6), 30% by mass (Example 7), 50% by mass (Example 8), and 80% by mass (Comparative Example 4). Was prepared. The total amount of the fluorinated solvent and other solvents was 400 parts by mass, the same as in Example 1. The content of the fluorosurfactant in the total amount of ink was 0.94% by mass.

<Example 9>
Example except that methylnonafluorobutyl ether (boiling point 76 ° C., surface tension 13.6 mN / m) was used as the fluorine-based solvent, and the content of the fluorine-based solvent in the total amount of the solvent was 30% by mass. Ink was prepared in the same manner as in Example 1. The total amount of the fluorinated solvent and other solvents was 400 parts by mass, the same as in Example 1. The content of the fluorosurfactant in the total amount of ink was 0.94% by mass.

<Example 10>
1,1,1,2,3,4,4,5,5,5-decafluoro-2-trifluoromethyl-3-methoxypentane (boiling point 55 ° C., surface tension 14.1 mN / m) as fluorine-based solvent Ink was prepared in the same manner as Example 1 except that the content of the fluorine-based solvent in the total amount of the solvent was 30% by mass. The total amount of the fluorinated solvent and other solvents was 400 parts by mass, the same as in Example 1. The content of the fluorosurfactant in the total amount of ink was 0.94% by mass.

<Example 11, Comparative Examples 5 and 6>
As a fluorinated solvent, instead of HFE-7200, two or more hydrofluoroethers were mixed to have a boiling point of 70 ° C. and a surface tension at 25 ° C. of 10 mN / m (Comparative Example 5). 100 mass parts each having a surface tension of 18 mN / m at 70 ° C. and 25 ° C. (Example 11) and one having a boiling point of 70 ° C. and a surface tension at 25 ° C. of 25 mN / m (Comparative Example 6) An ink was prepared in the same manner as in Example 1 except that it was blended.

In each ink, the content ratio of the fluorinated solvent in the total amount of the solvent was 25% by mass. Further, the content of the fluorosurfactant in the total amount of ink was 0.94% by mass.
<Examples 12 and 13, Comparative Examples 7 and 8>
As a fluorine-based solvent, instead of HFE-7200, two or more hydrofluoroethers were mixed to have a boiling point of 45 ° C. and a surface tension of 14 mN / m at 25 ° C. (Comparative Example 7). A surface tension at 55 ° C. and 25 ° C. of 14 mN / m (Example 12), a boiling point of 90 ° C., a surface tension at 25 ° C. of 14 mN / m (Example 13), and a boiling point of 160 ° C. An ink was prepared in the same manner as in Example 1 except that 100 parts by mass of each having a surface tension at 25 ° C. of 14 mN / m (Comparative Example 8) was blended.

<Example 14>
As a fluorine-based solvent, in place of HFE-7200, 100 parts by mass of a mixture of two or more hydrofluorocarbons and having a boiling point of 70 ° C. and a surface tension of 14 mN / m at 25 ° C. An ink was prepared in the same manner as in Example 1.
<Conventional example 1>
An ink was prepared in the same manner as in Example 1 except that 400 parts by mass of normal hexane, which is a conventional low-tensile solvent, was blended in place of the HFE-7200 and PGMEA.

<Conventional example 2>
As a solvent, an ink was prepared in the same manner as in Example 1 except that the HFE-7200 was not blended and only 400 parts by mass of PGMEA was blended.
<Printing test>
Striped ink patterns (line width 100 μm, pitch 300 μm) of each color of red, green and blue on a glass substrate by reversal printing using a silicone blanket using the inks of each color prepared in Examples and Comparative Examples Were sequentially printed to produce a color filter for LCD.

As the silicone blanket, one having a laminated structure in which a layer of 0.6 mm thick silicone rubber was laminated on one side of a 0.35 mm thick PET film was used.
A slit die coater was used to form an ink layer on substantially the entire surface of the silicone blanket.
The following items were evaluated through the manufacturing process of the color filter described above by the reverse printing method.

(Ink layer state)
The ink layer formed on substantially the entire surface of the silicone blanket using the slit die coater was visually observed and observed using an optical microscope to determine the presence or absence of pinholes, the presence or absence of vertical stripes, and the presence or absence of unevenness, respectively. Evaluated by criteria.
* Pinhole ○: No pinhole was found in the ink layer.

X: A pinhole was seen in the ink layer.
* Vertical stripes A: No vertical stripes were observed in the ink layer.
○: Although slight vertical stripes were observed in the ink layer, there was no problem in practical use.

X: Many vertical stripes were observed in the ink layer.
* Unevenness A: The ink layer was uniform with no unevenness.
A: Slight unevenness as seen by an optical microscope was observed in the ink layer, but it was practically acceptable.

X: Unevenness that can be seen visually was observed in the ink layer.
(Print shape)
The ink pattern printed on the glass substrate was observed visually and using an optical microscope, and the shape disorder was evaluated according to the following criteria.
A: No irregular shape was found in the ink pattern.

A: The ink pattern was slightly disturbed to the extent that can be seen with an optical microscope, but it was practically acceptable.
X: Disturbance to the extent that the ink layer can be visually confirmed was observed.
The above results are shown in Tables 1-5. In Tables 3 to 5, the results of Example 1 are also shown for comparison. Abbreviations in each table are as follows.

HFE: Hydrofluoroethers HFC: Hydrofluorocarbons n-Hex: Normal hexane PGMEA: Propylene glycol monomethyl ether acetate

From the results of Examples 1 to 14 in Tables 1 to 5 and Conventional Examples 1 and 2 in Table 5, by using a fluorine-based solvent and another solvent as a solvent, the surface of the silicone blanket is moderate. It has been found that an ink that has both wettability and releasability and is less likely to cause safety problems, vertical stripes, unevenness, and the like can be obtained.
Moreover, from the results of Examples 1 to 5 and Comparative Examples 1 and 2 in Table 1 and Examples 6 to 8 and Comparative Examples 3 and 4 in Table 2, the content ratio of the fluorinated solvent is 5 mass to obtain the above effect. It has been found that it is necessary to be not less than 50% by mass and not more than 50% by mass, and in particular, it is preferably not more than 30% by mass.

Further, from the results of Examples 1 and 11 and Comparative Examples 5 and 6 in Table 3, in order to obtain the above effect, a fluorine-based solvent having a surface tension at 25 ° C. of 12 mN / m or more and 18 mN / m or less is used. It has been found that it is necessary, and in particular, it is preferably 16 mN / m or less.
From the results of Examples 1, 12, 13 and Comparative Examples 7 and 8 in Table 4, it is necessary to use a fluorine-based solvent having a boiling point of 50 ° C. or higher and 150 ° C. or lower in order to obtain the above effect. In particular, it was found that the temperature is preferably 60 ° C. or higher.

  Further, from the results of Examples 7, 9, and 10 in Table 2 and Examples 1 and 14 in Table 5, it is preferable to use hydrofluoroethers or hydrofluorocarbons as the fluorinated solvent in order to obtain the above-mentioned effects. I understood.

DESCRIPTION OF SYMBOLS 10 Silicone blanket 11 Ink 12 Ink layer 13 Cylinder 14 Slit die coater 15 Ink supply part 16 Slit nozzle 17 Plate 18 Convex part 19 Concave part 20 Ink pattern 20 Colorant 21 Substrate 22 Liquid crystal color filter 23 Transparent substrate

Claims (6)

  An ink layer formed on substantially the entire surface of the silicone blanket is brought into contact with the surface of the plate having a recess corresponding to a predetermined ink pattern on the surface, and the ink layer other than the recess is transferred to the surface of the plate. Then, after selectively removing from the surface of the silicone blanket to form an ink pattern corresponding to the concave portion on the surface of the silicone blanket, the ink pattern is used in a reverse printing method for printing on the surface of the substrate. An ink comprising a binder resin, a colorant, and a solvent, the solvent having a boiling point of 50 ° C. or higher and 150 ° C. or lower and a surface tension of 12 mN / m or higher and 25 m or less of a fluorine-based solvent of 5 mass % Ink and a ratio of 50% by mass or less.   The ink according to claim 1, wherein the fluorinated solvent is at least one selected from the group consisting of hydrofluoroethers and hydrofluorocarbons.   The ink according to claim 1 or 2, wherein the fluorine-containing surfactant is contained at a ratio of 0.1% by mass or more and 1% by mass or less in the total amount of the ink.   Using the ink according to any one of claims 1 to 3, an ink layer formed on substantially the entire surface of the silicone blanket is brought into contact with the surface of the plate having a recess corresponding to a predetermined ink pattern on the surface. After the ink layer other than the recesses is transferred to the surface of the plate, the ink blank is selectively removed from the surface of the silicone blanket to form an ink pattern corresponding to the recesses on the surface of the silicone blanket. A reversal printing method, wherein the ink pattern is printed on a surface of a substrate.   5. A transparent substrate, a color filter layer formed on the transparent substrate, and a black matrix layer, wherein at least one of the color filter layer and the black matrix layer is formed by a reverse printing method according to claim 4. Liquid crystal color filter characterized by being made.   A method for producing a liquid crystal color filter, comprising a step of forming at least one of a color filter layer and a black matrix layer on a transparent substrate by the reversal printing method according to claim 4.

Images