High-precision screen printing screen structure and ink composition improvement (on)

Preface

The color filter used in the field of displays is a surface of a transparent plate such as glass, and a wiring pattern is formed by vertically and horizontally arranging two or more fine pixels of different hue. One pixel varies in size from tens of micrometers to several hundred micrometers, and each hue is constructed in a certain order and arrangement. For this reason, there are various methods for manufacturing a color filter, and a common method is to uniformly disperse colorants such as dyes and pigments in a colored resist in a transparent photosensitive resin, apply the coating, and expose and develop. The prescribed shape forms a dyeing pattern, which is a pigment dispersion method that can achieve mass production. However, in terms of large-formatization and coating of raw materials, it needs further improvement.

In view of the above problems, the display field has begun to pay attention to adapting to large-scale screen production and printing technologies. At the same time, screen printing has also been requested to be more refined. Screen printing has long been applied in the fields of commercial advertising such as large-format posters and electronic components such as printed circuit boards. It is a printing method that does not rely on the characteristics of substrates and saves materials.

In order to realize high-precision screen printing, efforts must be made to minimize the degree of tension reduction caused by the change of the screen printing time with the printing time, and a good resolution resist material must be used. However, no effective resist has been found so far. In addition, from the viewpoint of improving the printing accuracy, it is also necessary to further improve the elements that affect high-definition screen printing.

Therefore, this study is mainly to improve the original screen structure and ink composition, optimize the relevant materials, and then discuss the new high-definition screen printing method (HADOP method). A 40μm sharp line print that attenuates the image edge and has a very high linearity, thus promoting the application of color filter production.

Experimental materials and methods

1. Synthesis of transparent resist material for plate making and ink
The transparent resist was prepared by mixing a polymer, a monomer, and a photopolymerization initiator in a ratio of 6:4:3.

The photopolymerization initiators are TAZ-106 (5-triazabenzenes manufactured by Green Chemical Industries, Ltd.) and 2-hydroxy-2-dimethoxy-1-phenylpropane-1-one (manufactured by Chiba Gagyo Co., Ltd.). ) Mix in a 4:1 ratio and prepare an initiator solution using cyclohexanone as the solvent. Among them, commercially available special grade reagents were used as monomers, photopolymerization initiators, and various reagents including solvents, but the following compositions were used as the polymers.

The solvent used was 3-methoxy butyl acetic acid, and the various acrylic monomers of benzyl methacrylate (BzMA), styrene (St), and 2-methacrylic acid (MMA) were 1:1:1. After the mixture is mixed, the azobisisobutyronitrile (AIBN), which is a radical polymerization initiator, is further stirred at 80° C. for 6 hours to obtain a terpolymer after polymerization of the radicals. Further, in the MMA of the terpolymer, the original partial hydroxyl group was subjected to an addition reaction with glycidyl methacrylate (GMA) to synthesize a double bond-introduced quaternary copolymer (P-1).

Except for this, the MMA was changed to acrylic acid (AA), and similarly to P-1, an addition reaction of a part of hydroxyl groups with GMA was carried out to synthesize a double-bonded four-way copolymer (P-2). In order to compare plate-making characteristics, a commercially available polymer was also used, and a commercial propylene polymer ACA-200 (Disell UCB) was used as a commercial polymer.

2. Preparation of pigment dispersion resist ink
The pigment-dispersed resist ink had a ratio of pigment to clear resist of 1:4, the solvent was propylene glycol methyl ether acetate (PGMEA), and the pigment was CIRed 177, CI Green 36, CI Blue 15:3. The preparation method was as follows: 200 g of CI Red 177 pigment, 167 g of dispersant Disperbyk 161 (30% non-volatile content), and 633 g of PGMEA were mixed and dispersed for 24 hours using a granule stirrer. The transparent resist was added in a prescribed amount and uniformly stirred. After filtering with a filter with a pore size of 2 μm, a red dispersion resist ink was obtained. In order to compare with the conventional screen printing method, an ordinary screen printing ink (EG-RED manufactured by Sun Ink Co., Ltd.) was used in the experiment.

(to be continued)