JPH0587310B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a technique for drying a coating film formed using a coating solution containing a polyimide precursor solution as a main component, and in particular, to drying the coating film using a polyimide resin. The present invention relates to a technique suitable for forming a lower layer pattern as a main component so as to cover it.

(Prior Art) Polyimide resins are excellent in various resistances such as heat resistance, chemical resistance, and light resistance, and have been conventionally used in many fields as protective coatings or pattern forming materials.

One such field is color filters used in color liquid crystal display devices, color video cameras, and the like. A color filter has two or more filter pixel groups having mutually different spectral characteristics, generally red, green,
It includes three filter pixel groups corresponding to blue, and polyimide resin is used, for example, as a material for forming each filter pixel group.

By the way, when forming each filter pixel group using polyimide resin, it is necessary to form a lower layer pattern mainly composed of polyimide resin, that is, to form a filter pixel group of a different color on top of a filter pixel group of a certain color. A coating film is formed by spin coating, coating with a roll coater, or other coating method using a coating solution containing a polyimide precursor solution as a main component. However, since the solvent in the polyimide precursor solution has the disadvantage of causing cracks, wrinkles, etc. in the underlying pattern, conventionally, as described in JP-A-60-247603, for example, An intermediate protective film made of acrylic resin or the like is interposed between the lower layer pattern and the coated film.

(Problems to be Solved by the Invention) However, when the intermediate protective film is provided, there arises a problem that the manufacturing process is complicated and that the flatness of the color filter is deteriorated.

An object of the present invention is to provide a technique that allows the intermediate protective film, which causes such problems, to be omitted.

Each filter pixel group in the color filter has a different color, but as a method to improve the uniformity of each color, when forming each filter pixel group, the solution is added to the polyimide precursor solution. It is preferable to use a solvent-containing polyimide resin solution containing a dye soluble in the solvent as the coating solution. This is because the solvent can be more easily and uniformly dispersed in the polyimide precursor solution than the pigment since it is soluble in the solvent. However, this method is not very welcome from the viewpoint of omitting the intermediate protective film. Because the dye is soluble,
This is because if the intermediate protective film is omitted, there is a risk of color mixing between the lower layer and the upper layer.

Another object of the present invention is to provide a technique that can solve such color mixing problems.

(Means for Solving the Problems) In the present invention, after forming a coating film on one surface of a substrate having a lower layer pattern mainly composed of polyimide resin using a coating solution containing a polyimide precursor solution as a main component, , when drying the coated film, a first step of drying the coated film at a temperature lower than (A) the boiling point of the solvent in the polyimide precursor solution, and then (B) a step close to the boiling point. The drying process is performed through a second step in which the drying process is performed by heating at a certain temperature. Here, the processing temperature in the first step is 80°C or lower, preferably room temperature, and the processing temperature in the second step is 120 to 170°C.
℃, preferably around 150℃.

(Function) Before being heat-treated at a relatively high temperature in the second step, it is naturally dried or dried at a low temperature in the first step. Therefore, in the first step, most of the solvent in the applied film is removed, and the film loses its fluidity. Therefore, in the second step of heating at a relatively high temperature, only a small amount is present in the solvent, and even if the intermediate protective film is omitted, it will cause damage to the existing underlying pattern as described above. Never.

(Example) As a color filter for a liquid crystal color display device,
As shown in FIG. 1, a grid-like black light shielding pattern 12, a red filter pixel group 14, a green filter pixel group 16, a blue filter pixel group 18 are formed on a glass substrate 10, and a transparent layer covers the top layer. A color filter 22 having a protective film layer 20 was manufactured in the following manner.

First, a black coating solution was spin-coated onto the glass substrate 10 using a spinner at 1000 rpm for 90 seconds to form a black coating film. The coated film is dried by leaving it at room temperature for 30 minutes to the extent that the coated film loses its fluidity. The applied film is sufficiently leveled by the drying treatment in the first step, and most of the solvent contained therein is evaporated. next,
The coated film is further dried at 150° C. for 5 minutes using a heated hot plate. This second drying process brings the applied film into a semi-cured state. Next, we applied a positive photoresist at 3000 rpm for 30 seconds, and
Dry for 30 minutes. This is exposed to light through a photomask using an ultraviolet exposure device, and then developed with a sodium hydroxide solution, and at the same time, the black coating film is etched. Thereafter, the unexposed portions of the positive photoresist are peeled off with cellosolve acetate and baked at 250° C. for 60 minutes to form a lattice-shaped light-shielding pattern 12. Thereafter, in the same manner, red filter pixel group 14 and green filter pixel group 1
6. Sequentially form blue filter pixel groups 18.
After each pattern is formed, the uppermost protective film 20 is formed by the spin coating method.

Here, the composition of each coating solution is shown below.

(For black) Solvent Black 3 1.0g Polyimide precursor solution (Semicofine, manufactured by Toray Industries, Inc.) 5.0g Methyl cellosolve 15.0g (For red) Acid Red 257 0.5g Polyimide precursor solution (Semicofine, manufactured by Toray Industries, Inc.) 5.0g Methyl cellosolve 8.5g (for green color) Solvent Yellow 77 0.5g Acid Blue 7 0.5g Polyimide precursor solution (manufactured by Toray Industries, Inc., Semicofine) 5.0g Methyl cellosolve 8.5g (for blue color) Solvent Blue 42 0.5g Polyimide precursor solution ( (Manufactured by Toray Industries, Inc., semicofain) 5.0 g Methyl cellosolve 8.0 g (For protective film layer) Polyimide precursor solution (manufactured by Toray Industries, Inc., semicofain) 5.0 g Methyl cellosolve 7.5 g (Effects of the invention) In this invention, polyimide resin is mainly used. After forming a coating film on one surface of a substrate having a lower layer pattern as a component using a coating solution containing a polyimide precursor solution as a main component, when drying the coating film, immediately after applying the coating film, natural After drying or low-temperature drying, drying is performed at a relatively high temperature. Therefore, even without forming an intermediate protective film that is conventionally required, damage to the existing underlying pattern can be avoided, and quality can be improved and the process can be simplified. especially,
When applied to the color filter of this invention, the smoothness of the filter can be improved, and furthermore, uniform color characteristics can be obtained by using a dye as a coloring agent for the polyimide resin.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a color filter manufactured according to the present invention. 10...Substrate, 12...Black light shielding pattern, 14
... Red filter pixel group, 16... Green filter pixel group, 18... Blue filter pixel group, 20... Protective film layer, 22... Color filter.

Claims (1)

[Claims] 1. A coating film is formed on one surface of a substrate having a lower layer pattern containing a polyimide resin as a main component using a coating solution containing a polyimide precursor solution as a main component, and then the coating film is dried. In the method of
A first step of drying the applied film at a temperature lower than the boiling point of the solvent in the polyimide precursor solution, and then (B) drying the coated film by heating it at a temperature close to the boiling point. A method for drying a coated film, comprising sequentially performing a second step of drying. 2. The lower layer pattern is a colored pattern containing a dye in a polyimide resin, and the coating solution is a dye-containing polyimide formed by mixing a dye dissolved in a solvent of the solution into a polyimide precursor solution. The method for drying a coating film according to claim 1, which is a resin solution. 3 The temperature in the first step is 80°C or lower, and the temperature in the second step is
A method for drying a coated film according to claim 1 or 2, wherein each drying treatment is performed at a temperature of 120 to 170°C.