Flexographic printing plate and method for manufacturing liquid crystal display element using same
阅读说明:本技术 柔版印刷版与使用其的液晶显示元件的制造方法 (Flexographic printing plate and method for manufacturing liquid crystal display element using same ) 是由 田所信彦 中下武文 高桥俊行 山本胜志 于 2019-08-21 设计创作,主要内容包括:本发明提供一种柔版印刷版及液晶显示元件的制造方法,所述柔版印刷版可高精度且并无厚度不均或针孔等、并且不会大幅变更印刷条件地形成厚度比现状大且为适合于液晶显示元件用途的厚度的液晶取向膜等,所述液晶显示元件的制造方法包括使用所述柔版印刷版并利用柔版印刷法来形成液晶取向膜的工序。柔版印刷版(1)是将用于担持油墨的版表面(3)设为比表面积RS为4.3以上且6.0以下、单位空间容积SV为12μm3/μm2以上且29μm3/μm2以下的粗糙面。液晶显示元件的制造方法包括使用所述柔版印刷版并利用柔版印刷法来形成液晶取向膜的工序。(The present invention provides a flexographic printing plate capable of forming a liquid crystal alignment film having a thickness larger than the current state and suitable for use in a liquid crystal display element with high accuracy and without thickness unevenness, pinholes, and the like, and without greatly changing printing conditions, and a method for manufacturing a liquid crystal display element including a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate. The flexographic printing plate (1) has a plate surface (3) for supporting ink as a rough surface having a specific surface area RS of 4.3 to 6.0 inclusive and a unit space volume SV of 12 [ mu ] m 3/[ mu ] m2 to 29 [ mu ] m 3/[ mu ] m2 inclusive. The method for manufacturing a liquid crystal display element includes a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate.)
1. A flexographic printing plate comprising a plate surface for holding ink, and the plate surface has a specific surface area RSIs 4.3 to 6.0 inclusive and has a unit space volume SVIs 12 μm3/μm2Above and 29 μm3/μm2The following rough surface.
2. The flexographic printing plate of claim 1, wherein the plate surface has a specific surface area RSIs 5.0 to 5.3 inclusive.
3. The flexographic printing plate of claim 1 or 2, wherein the volume per space S of the plate surfaceVIs 16 μm3/μm2Above and 22 μm3/μm2The following.
4. A method for manufacturing a liquid crystal display element, comprising a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate according to any one of claims 1 to 3.
Technical Field
The present invention relates to a flexographic printing plate and a method for manufacturing a liquid crystal display element using the same.
Background
For example, in a wide range of printing fields such as printing of packaging materials, a flexographic printing method is commonly used.
The following flexographic printing plates were used in the flexographic printing process: the ink-jet printing sheet includes a flexible resin sheet or the like, and the surface of the sheet is formed into a plate surface, that is, a surface that contacts a surface to be printed while holding ink and transfers the ink to the surface to be printed.
It is known that the flexographic printing method has good printing characteristics, and is also used for printing a liquid crystal alignment film of a liquid crystal display device, for example, as a special application other than the general application in which the flexographic printing method is effectively used.
In printing of a liquid crystal alignment film, the following requirements are required: reducing the thickness of a liquid crystal alignment film formed by transferring ink from the plate surface to a printed surface of a flexographic printing plate; or even if the thickness is reduced, the thickness precision of the liquid crystal orientation film is high, and uneven thickness, pinholes and the like are not generated.
As the ink for forming the liquid crystal alignment film with high accuracy and without thickness unevenness, pin holes, and the like, an ink which has low wettability to a resin or the like forming a flexographic printing plate and is easily released from the plate surface is suitably used.
Further, even when the ink has low wettability, a flexographic printing plate is used which has a plate surface having a rough surface with a constant specific surface area so as to support the plate surface while maintaining a uniform thickness without causing thickness unevenness or pinholes due to repulsion or the like (see
The flexographic printing plate is manufactured through the following steps: the surface of the layer of the photosensitive resin composition is brought into contact with the mold surface of a roughened sheet having a mold surface of a roughened surface corresponding to the roughened surface formed as the plate surface, and the photosensitive resin composition is cured by exposure to actinic rays such as ultraviolet rays in the above state.
When the roughened surface sheet is peeled off after curing, the three-dimensional shape of the mold surface of the roughened surface sheet is transferred to the surface of the layer of the cured photosensitive resin composition, and the surface is made into a roughened plate surface having a three-dimensional shape corresponding to the three-dimensional shape of the mold surface.
Hereinafter, the method for producing the flexographic printing plate may be simply referred to as "exposure transfer method".
The roughened sheet is produced by roughening one surface of a sheet to be a base thereof into a predetermined three-dimensional shape by press sheet molding using an emboss roller having an outer peripheral surface roughened by, for example, etching or molding by etching.
[ Prior art documents ]
[ patent document ]
[ patent document 1] Japanese patent laid-open publication No. 2013-119179
[ patent document 2] Japanese patent laid-open No. 2014-133335
Disclosure of Invention
[ problems to be solved by the invention ]
However, when the conventional flexographic printing plates described in
In addition, in the conventional technique, in order to increase the thickness of the liquid crystal alignment film, it is necessary to change various printing conditions.
That is, it is necessary to change an anilox roll for supporting ink on the plate surface, change the composition of ink, change nip pressure (nip pressure), change the printing speed, and the like.
However, there are problems as follows: a great deal of effort and cost are required to change these printing conditions.
The purpose of the present invention is to provide a flexographic printing plate which can form a liquid crystal alignment film or the like having a thickness larger than the current state and suitable for use in liquid crystal display elements with high accuracy and without thickness unevenness or pinholes or the like, and without significantly changing printing conditions.
Another object of the present invention is to provide a method for manufacturing a liquid crystal display element, the method including a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate.
[ means for solving problems ]
The invention relates to a flexographic printing plate, which comprises a plate surface for supporting ink, wherein the plate surface has a specific surface area RSIs 4.3 to 6.0 inclusive and has a unit space volume SVIs 12 μm3/μm2Above and 29 μm3/μm2The following rough surface.
The present invention is also a method for manufacturing a liquid crystal display element, including a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate.
[ Effect of the invention ]
According to the present invention, it is possible to provide a flexographic printing plate which can form a liquid crystal alignment film or the like having a thickness larger than the current state and suitable for use in a liquid crystal display element with high accuracy and without thickness unevenness or pinholes or the like, and without greatly changing printing conditions.
Further, according to the present invention, there can be provided a method for manufacturing a liquid crystal display element, the method including a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate.
Drawings
Fig. 1 is a perspective view showing an example of an embodiment of a flexographic printing plate of the present invention.
Fig. 2 is a perspective view illustrating a method of determining a specific surface area and a unit space volume of a plate surface of a flexographic printing plate.
Fig. 3 is a cross-sectional view showing an example of a three-dimensional shape of a plate surface of a flexographic printing plate.
Fig. 4 is a sectional view showing a layer structure of an example of a roughened sheet used for manufacturing a flexographic printing plate.
Fig. 5(a) to 5(c) are cross-sectional views showing an example of a process for producing the flexographic printing plate of the example of fig. 1.
Fig. 6(a) to 6(c) are cross-sectional views showing an example of the subsequent steps of fig. 5(a) to 5 (c).
FIG. 7 is a photomicrograph of the plate surface of an embodiment of the present invention.
Fig. 8 is a photomicrograph of the plate surface of the comparative example.
[ description of symbols ]
1: flexographic printing plate
2: resin layer
3: plate surface
4: reinforced sheet
5: gripping part
6: trough part
7: chuck hole
8: hollow depression
9: printing ink
10: roughened sheet
11: reinforced membrane
12: surface layer
13: adhesive resin
14: fine particles
15: die surface
16: supporting substrate
17: opposite side
18: surface of
19: photosensitive resin composition
20: layer(s)
21: opposite substrate
22: facing surface
23: laminated body
24: work bench
25: resin original plate for printing
A: measurement area
H: height of space
PH: highest point
PL: lowest point
RS: specific surface area
SV: volume per unit space
V: convex volume
W1: longitudinal direction
W2: horizontal bar
Detailed Description
Flexographic printing plate
Fig. 1 is a perspective view showing an example of an embodiment of a
Referring to fig. 1, a
A
Further, a
Further, chuck holes 7 for inserting fixing pins (not shown) into the
< specific surface area RSAnd unit space volume SV>
The
The reason for this is as follows.
I.e. the specific surface area RSA relatively
In addition, the specific surface area RSThe
Therefore, in any of the above cases, the accuracy of the thickness of the liquid crystal alignment film formed by transferring the carried ink to the surface to be printed is lowered, and unevenness in thickness, pinholes, and the like are likely to occur in all of them.
In addition, the specific surface area RSThe relatively
In addition, the unit space volume SVThe volume of the
If the unit space volume SVLess than 12 μm3/μm2The amount of ink that can be carried by the
On the other hand, the unit space volume SVOver 29 μm3/μm2The
Therefore, the accuracy of the thickness of the liquid crystal alignment film formed by transferring the ink carried by the liquid crystal alignment film to the surface to be printed is lowered, and unevenness in thickness, pinholes, and the like are likely to occur.
In contrast, the specific surface area R of the
In addition, the amount of ink that can be carried on the
And, only by adjusting the unit space volume S within the rangeVThe amount of ink that can be carried on the
Therefore, a liquid crystal alignment film having a thickness larger than the current state and suitable for use in a liquid crystal display element, for example, can be formed with high accuracy without thickness unevenness, pinholes, and the like, and without greatly changing printing conditions.
Further, in order to further improve these effects, the specific surface area R of the
In addition, the unit space volume SVIn said range, preferably 16 μm3/μm2Above, and preferably 22 μm3/μm2The following.
(measurement method)
Specific surface area RSAnd unit space volume SVFor example, the three-dimensional data can be obtained from three-dimensional data of the
FIG. 2 is a view illustrating the determination of the specific surface area R by using the shape analysis laser microscopeSAnd unit space volume SVPerspective view of the method of (1).
First, on the
Then, the actual surface area S [ mu ] m of the
RS=S/S0(1)
determination of specific surface area RS。
Further, the lowest point P of the
Then, these results are compared with the reference area S of the measurement region A0[μm2]And by the formula (2):
SV=H×S0-V (2)
determining each of the reference areas S0[μm2]Is the unit space volume SV[μm3/μm2]。
Stereoscopic shape of
In order to set the
That is, the conventional rough surface formed by etching or the like is generally a three-dimensional shape in which a convex portion and a valley portion having a substantially triangular wave-shaped cross section are continuous, as shown in fig. 2, for example.
However, according to the study of the inventors, the conventional rough surface having the three-dimensional shape may be as follows: even the specific surface area RSSatisfies the above-mentioned range of 4.3 to 6.0, and has a unit space volume SVAlso fails to satisfy 12 μm3/μm2The above range.
Fig. 3 is a cross-sectional view showing an example of a three-dimensional shape of the
In order to simultaneously control the specific surface area R of the
Thereby, the unit space volume SVSet to 12 μm3/μm2As described above, by increasing the amount of the
In order to manufacture the
For example, the
Among them, the
Specifically, the
Further, a reinforcing
Roughened sheet
Fig. 4 is a cross-sectional view showing a layer structure of an example of the roughened
Referring to fig. 4, the
The surface layer 12 includes a
In the example shown in the figure, the surface of the protruding fine particles 14 is coated with an extremely thin film containing the
However, the surface of the fine particles 14 may be exposed without being coated with a film, or a coated portion and an exposed portion may be mixed.
The surface layer 12 is formed by, for example, applying a coating agent including a
The roughened
The produced roughened
As the
Examples of the
Particularly preferred are thermoplastic, two-pack curable, actinic ray curable, or thermosetting acrylic resins, and among them, acrylic polyurethane two-pack curable acrylic resins are preferred.
Examples of the acrylic urethane two-pack curable acrylic resin include a resin obtained by combining a main agent containing an acrylic polyol and a curing agent containing isocyanate.
In short, since the acrylic resin has high affinity or wettability with the photosensitive resin composition which forms the base of the
As the fine particles 14, one or more kinds of particles of a resin, particles of an inorganic material, or the like can be used.
Examples of the resin particles include particles of acrylic resin, silicone resin, polystyrene, polycarbonate, and the like.
Examples of the particles of the inorganic material include: particles of glass, titanium oxide, barium sulfate, talc, clay, alumina, calcium carbonate, silica, and the like.
Among them, the fine particles 14 are preferably fine particles 14 containing a material that is transparent to actinic rays such as ultraviolet rays, which are exposed when the photosensitive resin composition is cured to form the
The coating agent is prepared, for example, by blending a base agent and a curing agent, which are bases of the coating agent, with the fine particles 14 at a predetermined ratio and, if necessary, adding a solvent, when an acrylic resin of an acrylic urethane two-pack curing type is used as the
The reinforcing
As the reinforcing
In particular, the PET film is preferably a PET film that is transparent to actinic rays such as ultraviolet rays that are exposed when the
Among them, as the reinforcing
If necessary, primer treatment may be performed on one surface (upper surface in the figure) of the laminated surface layer 12 of the reinforcing
Examples of the primer treatment include one or more of corona discharge treatment, flame treatment, ozone treatment, ultraviolet irradiation treatment, blast treatment, solvent treatment, and the like.
For example, a primer layer including various materials having excellent affinity and adhesion with the PET forming the reinforcing
The minimum value of the particle size distribution (particle size distribution) of the fine particles 14 forming the surface layer 12 is preferably 4 μm or more, and particularly preferably 4.5 μm or more, and the maximum value of the particle size distribution is preferably 30 μm or less, and particularly preferably 25 μm or less.
The minimum value and the maximum value of the particle size distribution mean the minimum value and the maximum value of the particle size in the measurement result of the particle size distribution obtained for the fine particles 14 to be measured.
When the minimum value of the particle size distribution of the fine particles 14 is less than 4 μm, the fine particles 14 include: the
On the other hand, in the case where the maximum value of the particle size distribution of the fine particles 14 exceeds 30 μm, the fine particles 14 include the following particles: for setting the
Therefore, there are cases where: although depending on the coating thickness of the coating agent, the blending ratio of the fine particles 14, etc., in any case, the
Further, the liquid crystal alignment film formed by the flexographic printing method may have insufficient thickness or may have low thickness accuracy, which may cause thickness unevenness or pinholes.
In contrast, by setting the minimum value and the maximum value of the particle size distribution of the fine particles 14 to the above ranges, the particles having an excessively small particle size or the particles having an excessively large particle size can be excluded.
Therefore, the
The fine particles 14 are preferably formed by combining the standard deviation σ of the particle size distribution and the average particle size according to formula (3):
coefficient of variation Cv ═ standard deviation σ)/(average particle diameter) (3)
The coefficient of variation Cv obtained and indicating the variation in particle size distribution is 0.35 or less.
When the coefficient of variation Cv exceeds 0.35, the deviation of the particle size distribution becomes large, and the fine particles 14 include a large amount of the particles having an excessively small particle size or particles having an excessively large particle size.
Therefore, there are cases where: although it still depends on the coating thickness of the coating agent, the blending ratio of the fine particles 14, and the like, the
In contrast, by setting the coefficient of variation Cv to the above range, particles having an excessively small particle size and particles having an excessively large particle size can be excluded.
Therefore, the
In order to further enhance the above effect, the coefficient of variation Cv is preferably 0.25 or less within the above range.
However, when the coefficient of variation Cv is too small, the pitches of the irregularities formed on the
In this case, the range of pitches itself is a single pitch although it is different, and moire (moire) fringes may occur in the liquid crystal alignment film formed on the electrode-formed surface due to interaction with the electrode-formed surface including the portion formed with the irregularities, for example, the substrate constituting the liquid crystal display element.
Therefore, in consideration of suppressing the occurrence of moire, the coefficient of variation Cv is preferably 0.10 or more, and particularly preferably 0.18 or more within the above range.
In addition, even in this case, for the reasons described above, the minimum value of the particle size distribution of the fine particles 14 is preferably 4 μm or more, and particularly preferably 4.5 μm or more, and the maximum value of the particle size distribution is preferably 30 μm or less, and particularly preferably 25 μm or less.
In order to suppress the occurrence of moire, a mixed particle of two types of fine particles having different particle size distributions may be used as the fine particle 14.
When the mixed particles of two types of fine particles having different particle size distributions are used in combination, the pitch of the irregularities formed on the
Therefore, for example, by interaction with the electrode formation surface of the substrate constituting the liquid crystal display element, moire can be suppressed from occurring in the liquid crystal alignment film formed on the electrode formation surface.
In addition, even in this case, for the reason described above, the coefficient of variation Cv of the entire mixed particle is preferably 0.35 or less, particularly preferably 0.25 or less, and preferably 0.10 or more, particularly preferably 0.18 or more.
Further, it is preferable that the respective variation coefficients Cv of the two types of fine particles constituting the mixed particle are within the above ranges.
The range of the particle size distribution of the two types of fine particles constituting the mixed particle can be arbitrarily set.
The ranges of the particle size distributions of the two types of fine particles may be different from each other, or may be repeated in a part.
Among these, for the reasons described above, the minimum values of the particle size distributions of both types of fine particles are preferably 4 μm or more, particularly preferably 4.5 μm or more, and the maximum values of the particle size distributions are preferably 30 μm or less, particularly preferably 25 μm or less.
The blending ratio of the two types of fine particles may be set to any range depending on the range or variation coefficient Cv of the particle size distribution of each fine particle, the variation coefficient Cv of the whole mixed particle, or the like.
However, in order to further enhance the above-described effect of using the mixed particles, the proportion of fine particles having a small particle size distribution in the total amount of the mixed particles is preferably 10% by mass or more, and preferably 90% by mass or less.
In the present invention, the particle size distribution of the fine particles 14 or each fine particle constituting the mixed particle is represented by a volume distribution measured by a laser diffraction/scattering method based on Mie scattering theory.
The standard deviation σ that forms the basis of the coefficient of variation Cv is obtained from the result of conversion on a number basis assuming that the shape of the particle is spherical.
The average particle diameter is an arithmetic average diameter based on the number, which is obtained by integrating the shape of the particles assumed to be spherical and converted to the number and dividing the result by the number of the particles.
In the examples, the volume distribution of the fine particles was measured by using a laser diffraction/scattering particle size distribution measuring apparatus LA-950V2 manufactured by horiba, Ltd, but the measuring apparatus is not limited thereto.
The mixing ratio of the
However, if the amount of the
On the other hand, when the
In consideration of the size of the irregularities, etc., the surface layer 12 is preferably formed in the following state: the fine particles are embedded in the
Therefore, the blending ratio of the
The thickness of the surface layer 12, that is, the thickness from one surface of the reinforcing
For example, when the particle diameter of the fine particles 14 is in the range of 4 μm to 30 μm, the thickness of the surface layer 12 is not limited thereto, but is, for example, preferably 0.010mm (10.0 μm) or more and preferably 0.025mm (25.0 μm) or less.
The thickness of the reinforcing
When the thickness is less than the above range, the roughened
When the roughened
On the other hand, when the thickness of the reinforcing
Further, as the thickness of the reinforcing
In addition, in a portion where the thickness of the reinforcing
That is, unevenness may be easily generated in the distribution of the unevenness of the surface layer 12, that is, the
On the other hand, by setting the thickness of the reinforcing
In view of further uniformizing the three-dimensional shape of the
That is, as the thickness of the reinforcing
Particularly, in the case of combining with the fine particles 14 having the particle size range of 4 μm or more and 30 μm or less, the thickness of the reinforcing
This further improves the effect of making the three-dimensional shape of the rough surface uniform.
Among them, if the prevention of the break defect and the like is also considered, the thickness of the reinforcing
When a primer layer is formed on one surface of the reinforcing
In view of suppressing the occurrence of breakage as much as possible, the total thickness of the rough-surfaced
In view of improvement in handling properties of the roughened
Method for manufacturing flexographic printing plate
Fig. 5(a) to 5(c) are sectional views showing an example of a process for producing the
Fig. 6(a) to 6(c) are cross-sectional views showing an example of the subsequent steps of fig. 5(a) to 5 (c).
Referring to fig. 5(a), in the manufacturing method of this example, a
In addition, as the rough-surfaced
The roughened
Specifically, for example, while one end of the
The roughened
Therefore, it is preferable that the roughened
(i) The roughened
(ii) A suction groove is formed in the
(iii) The roughened
As the weakly adhesive layer used for the adhesive fixation in (i), any of the following layers can be used: a layer having weak adhesion to both the
The weakly adhesive layer is formed by applying an adhesive to at least one of the
After the weakly adhesive layer is formed, as shown by the arrow of the chain line in fig. 5(a), the roughened
In this case, the roughened
When the fixed roughened
For the adsorption and fixation in (ii), the
In the roughened
In this manner, the overlapped roughened
When the fixed
Next, referring to fig. 5(b), in the manufacturing method of this example, a predetermined amount of liquid photosensitive resin composition 19 that forms the base of the
The supplied photosensitive resin composition 19 is sandwiched between the roughened
Further, as shown by the arrow of the dashed line in fig. 5(b), the photosensitive resin composition 19 is spread on the
In this case, the
Next, referring to fig. 5(c), the facing
While the facing
In this state, the
At this time, the interval between the
The opposing
Here, the
In this case, for example, the photosensitive resin composition 19 may be cured by exposing the
In this case, since the photosensitive resin composition 19 may be cured by exposing the
Next, referring to fig. 6(a) and 6(b), the
Then, as shown by the arrow of the dashed line in fig. 6(b), the roughened
In this way, the roughened surface shape of the
Thereafter, although not shown, 4 sides of the printing resin
Next, as shown in fig. 1, the
If a predetermined print pattern is further formed on the
As the photosensitive resin composition 19, various resin compositions satisfying the following conditions can be used.
Can be hardened by exposure to actinic rays such as ultraviolet rays.
After hardening, it has a suitable flexibility or rubber elasticity for use in flexographic printing.
A cured product having excellent resistance (solvent resistance) to a solvent contained in ink used for printing or used for cleaning a printing plate can be formed.
The photosensitive resin composition satisfying these conditions is not limited to this, but examples thereof include a composition containing a prepolymer having a 1, 2-butadiene structure and an ethylenic double bond at the terminal, an ethylenically unsaturated monomer, and a photopolymerization initiator.
As the photopolymerization initiator, benzoin alkyl ether is preferable.
As the reinforcing
As described above, the reinforcing
Method for manufacturing liquid crystal display element
The present invention is a method for manufacturing a liquid crystal display element, including a step of forming a liquid crystal alignment film by a flexographic printing method using the flexographic printing plate of the present invention.
Other steps of the method for manufacturing a liquid crystal display element can be performed in the same manner as before.
That is, a transparent electrode layer corresponding to a predetermined matrix pattern or the like is formed on the surface of a transparent substrate such as a glass substrate, a liquid crystal alignment film is formed through the above-described steps, and the surface of the liquid crystal alignment film is subjected to alignment treatment by rubbing or the like as necessary to produce a substrate.
Then, 2 substrates were prepared, and a liquid crystal material was sandwiched between the substrates and fixed to each other with the transparent electrode layers aligned, thereby forming a laminate, and polarizing plates were further disposed on both outer sides of the laminate as needed, thereby manufacturing a liquid crystal display element.
The configuration of the present invention is not limited to the example in the drawings described above.
For example, in the
In the method for manufacturing the
In addition, various modifications can be made without departing from the scope of the present invention.
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