KR101332428B1 - Flexible substrate with filler for display apparatus - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible substrate for display containing an inorganic particle filler. In the present invention, a flexible substrate for display containing an inorganic particle filler used in flat displays such as liquid crystal displays, organic EL displays, plasma display panels, and electronic papers. At least one heat-resistant resin selected from polyethylenenaphthalate, polyethersulfone, polyimide, polyethyleneterephthalate, polyarylate and polycarbonate, An inorganic particle filler comprising at least one inorganic particle filler selected from silicon dioxide (SiO 2), barium sulfate (BaSO ₄ ), boehmite, and wollastonite having an aspect ratio of 1 to 3,000. Plex for containing displays A sub substrate is provided.

Heat resistant resins; Inorganic Particle Filler

Description

Flexible substrate for display containing inorganic particle fillers {FLEXIBLE SUBSTRATE WITH FILLER FOR DISPLAY APPARATUS}

The present invention relates to a flexible substrate for display containing an inorganic particle filler, and more particularly to a flexible substrate for display containing an inorganic particle filler that increases the heat resistance of the transparent resin and reduces the coefficient of linear expansion.

Flat panel displays represented by liquid crystal displays, organic EL displays, plasma display panels, electronic papers, and the like are made of thin, light weight, low power consumption, and the like, such as thin televisions, computer displays, laptop personal computers, mobile phones, car navigation systems, and the like. Is rapidly growing as a display device.

Conventionally, glass has been used as the substrate material of these display elements. However, glass substrates are heavy because they have a high specific gravity, and are weak in impact strength and easily cracked. The use of plastics for substrates enables thin and light weights, and can be applied to flexible displays. Therefore, development of displays using plastic substrates has been progressed mainly in liquid crystal displays and organic EL displays.

However, in the process of manufacturing a liquid crystal display or an organic EL display, a high process temperature of 150 ° C to 200 ° C or more is required in a thin film transistor forming step, panel bonding step, alignment film forming step, transparent electrode forming step and the like. For this reason, high heat resistance is required for the display substrate. In addition, since the demand for display characteristics of displays is becoming more stringent each year, excellent optical characteristics are also required for display substrates.

Transparent resins and flexible resins include polymer epoxy resins, acid anhydride curing agents, and compositions using alcohols as curing catalysts. These resins have a high coefficient of linear expansion when compared to glass, and particularly active matrix display devices. It is known that curvature arises in the high temperature process to form, and causes problems, such as an aluminum wiring disconnection.

In order to solve this problem, there have been attempts to use transparent plastics having good heat resistance such as polycarbonate and polyether sulfone, but polycarbonate shows insufficient heat resistance, and polyether sulfone has a problem of coloring. It is known.

In order to further improve the heat resistance of the transparent resin, a technique related to a plastic substrate in which inorganic particle fillers such as glass are mixed in the transparent resin has been proposed. Most of the proposed techniques have difficulty in applying to a transparent substrate for a display. .

An object of the present invention is to provide a flexible substrate for display having an inorganic particle filler having a good coefficient of linear expansion and having a high transmittance and a glass transition temperature suitable for a display substrate.

The above object of the present invention is a flexible substrate for display containing inorganic particle fillers used in flat displays such as liquid crystal display, organic EL display, plasma display panel, electronic paper, polyethylenenaphthalate, polyethersulfone ), At least one heat resistant resin selected from polyimide, polyethyleneterephthalate, polyarylate, and polycarbonate, silicon dioxide (SiO2) having an aspect ratio of 1 to 3,000, It can be achieved by a flexible substrate for display containing an inorganic particle filler, characterized in that it comprises at least one inorganic particle filler selected from barium sulfate (BaSO ₄ ), boehmite and wollastonite.

The inorganic particle filler may be contained in an amount of 5 to 50 wt% based on the total weight of the mixture of the heat resistant resin and the inorganic particle filler. In the case of the inorganic particle filler, when the surface is etched, the contact area with the heat resistant resin becomes wider and thus heat resistant. The characteristic of resin can be improved more efficiently.

The flexible substrate for display having an inorganic particle filler having an aspect ratio of 1 to 3,000 manufactured by the present invention can improve the coefficient of linear expansion as compared to the flexible substrate for display without the inorganic particle filler.

In particular, even in the case of the inorganic particle filler having the same aspect ratio, by increasing the contact area with the heat-resistant resin by etching the surface it is possible to more efficiently improve the properties of the heat-resistant resin.

Examples of the transparent resin for forming the flexible transparent substrate for display that can be used in the present invention include polyethylenenaphthalate (hereinafter referred to as "PEN"), polyethersulfone (hereinafter referred to as "PES"), and polyimide (polyimide). Hereinafter referred to as "PI"), polyethylene terephthalate (hereinafter referred to as "PET"), polyarylate (hereinafter referred to as "PAR") and polycarbonate (hereinafter referred to as "PC") Each characteristic is shown in Table 1.

Compare PEN PES PI PET PAR PC CTE (ppm / ° C) 13 54 17 15 60 60 to 70 Tg (占 폚) 120 220 300 78 320 150 T (%) 88 89 89 89 90 90 Retar. (nm) height <10 - height - 41 WVTR
(g / m 2 · day) 2 105 135 9 - 50

At present, in the process of forming a thin film transistor using a glass substrate, attempts to form a flexible substrate for a display having a thin film transistor using a heat resistant resin made of a heat resistant resin shown in Table 1 in place of the glass substrate have been actively performed. When forming a flexible substrate with such a heat resistant resin, polyethylene naphtharate is not satisfactory in the glass transition temperature (Tg) and retardation characteristics, polyethersulfone and polyarylate has a high coefficient of linear expansion (CTE), polyimide It has poor water and vapor transmission rate, polyethylene terephthalate has a poor glass transition temperature (Tg) and delay characteristics, and polycarbonate has a glass transition temperature and coefficient of linear expansion that does not meet process standards. Can be.

It is known that the moisture and oxygen permeation properties can be solved by forming various barrier layers among the above characteristic values, and the delay characteristics are controllable according to the manufacturing method, and thus improvement of the linear expansion coefficient and glass transition temperature is most urgent. .

In order to compensate for the insufficient properties of the transparent resin having a high coefficient of linear expansion and low glass transition temperature, inorganic materials formed of minerals selected from silicon dioxide (SiO 2), barium sulfate (BaSO ₄ ), boehmite, and wollastonite When the particle filler is mixed with the transparent resin, the characteristics of the flexible transparent substrate for a display may be improved. In this case, it was found that the inorganic particle filler used can improve the characteristics of the flexible display substrate for display as the aspect ratio increases between the aspect ratios 1 to 3,000. In addition, in the case of the filler having the same aspect ratio, it was found that etching the filler surface to increase the contact area between the filler and the heat-resistant resin can improve the characteristics of the flexible display substrate for display.

It is preferable to mix content of an inorganic particle filler within the range which does not reduce the flexible substrate transmittance which consists of a heat resistant resin, Specifically, it consists of a compounding ratio within the range of 5-50 wt% with respect to the total capacity of the mixture of a heat resistant resin and a filler. It is good. This is because when the inorganic particle filler content is less than 5 wt%, the high linear expansion coefficient of the heat resistant resin itself cannot be sufficiently lowered, and when the inorganic particle filler content is more than 50 wt%, the transmittance of the resin itself is lowered and it cannot be used as a display panel substrate.

Example  One

After plasma treatment of the glass powder (SiO ₂ ) to form a silicon dioxide (SiO 2) filler having an aspect ratio of 1: 1, the polyallylate powder was mixed with metal chlorolite in a weight ratio of 1:15, and then the mixture was stirred with a heat resistant resin solution. After the formation, the silicon dioxide (SiO 2) filler was added to the polyallylate powder in a weight ratio of 2: 8 and mixed with agitation. The liquid polyallylate solution mixed with the silicon dioxide filler was heat-treated at 200 ° C. for about 1 hour to form a flexible transparent film for display of Example 1, and the coefficient of linear expansion of the film was measured. The silicon dioxide filler used at this time had a coefficient of linear expansion of 0.5 CTE (ppm / ° C.) by itself.

Example  2

After mixing the polyallylate powder with metal chlorolite in a weight ratio of 1:15, the mixture was stirred to form a heat resistant resin solution, and the boehmite filler having 7 CTE (ppm / ° C) and an aspect ratio of 4.5 was added to the polyallylate powder. The mixture was added at a weight ratio of 2: 8, followed by stirring. The liquid polyallylate solution mixed with the boehmite filler was heat-treated at 200 ° C. for about 1 hour to form a flexible transparent film for display of Example 2, and the coefficient of linear expansion of the film was measured.

Example  3

The polyallylate powder was mixed with metal chlorolite in a weight ratio of 1:15, followed by stirring to form a heat resistant resin solution, and in the formed solution, polyallylate a wollastonite filler having 7 CTE (ppm / ° C) and an aspect ratio of 3,000. The powder was added in a ratio of 2: 8 and then mixed with agitation. As a wollastonite filler, Nyglos W4 manufactured by Nyco Corporation was used. The liquid polyallylate solution mixed with wollastonite filler was heat treated at 200 ° C. for about 1 hour to form a flexible transparent film for display of Example 3, and the coefficient of linear expansion of the film was measured.

Example  4

0.5 g of Nyglos W4, a product of Nyco having 7 CTE (ppm / ° C) and an aspect ratio of 3,000, was immersed in a 10% to 15g sodium hydroxide 10% solution for 10 to 15 minutes at room temperature, filtered, washed with pure water and then surface This etched wollastonite filler was obtained. When the wollastonite reacts with sodium hydroxide, sodium metasilicate is formed in the reaction process, and thus it is removed using a filtering process and a washing process.

The polyallylate powder is mixed with metal chlorolite in a weight ratio of 1:15, and the mixture is stirred to form a heat resistant resin solution, and the surface-etched wollastonite filler formed by the above-described process is added at a weight ratio of polyallylate powder to the weight of 2: 8. After mixing whisk. The liquid polyallylate solution mixed with wollastonite filler was heat treated at 200 ° C. for about 1 hour to form a flexible transparent film for display of Example 4, and the coefficient of linear expansion of the film was measured.

Table 2 compares the coefficients of linear expansion (CTE) of the flexible substrates for display made of polyarylate only and the films prepared according to Examples 1 to 4, and the coefficients of linear expansion of the flexible substrate for display made of polyarylate only. Compared with (CTE) shows the rate of improvement of the coefficient of linear expansion (CTE) of the film produced according to each example.

PAR film without filler First Embodiment
film Second Embodiment
film Third Embodiment
film Fourth Embodiment
film CTE (ppm / ℃) 60 54 42 30 25 % Improvement 0% 6% 30% 50% 58%

In the case of the polyarylate substrate containing the inorganic particle filler, the CTE value increased as the aspect ratio of the filler contained increased to 1 (first example film), 4.5 (second example film), and 3,000 (third example film). 54, 42, and 30, showing a 6%, 30%, and 50% reduction in linear expansion coefficients compared to the filler-free PAR film, respectively. In particular, when the inorganic particle filler having its own CTE of 7 ppm / ° C. mixed with the inorganic particle filler having aspect ratios of 4.5 and 3,000, respectively, the coefficient of linear expansion was improved according to the aspect ratio. Shows. In addition, the linear expansion coefficient of the polyarylate substrate (fourth example film) having the 3,000 aspect ratio and the surface etched filler mixed was the linear expansion coefficient of the polyarylate substrate (the third example film) mixed with the same aspect ratio filler which was not surface etched. It can be seen that the reduction is about 17% from 30 ppm / ° C. to 25 ppm / ° C. when compared to the modulus.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the filler surface before surface etching advances, and the filler surface after surface etching. As shown in FIG. 1 (a), the surface of the filler 20 is smoothly formed before the surface is etched. However, when the surface is etched, as shown in FIG. ), The area is separated from the surface and in contact with the heat-resistant resin increases. Therefore, the increased filler surface and the heat resistant resin react in a larger area, thereby decreasing the coefficient of linear expansion.

While specific embodiments of the invention have been illustrated and described, it will be obvious that the same may be varied in many ways by those skilled in the art without departing from the spirit of the invention. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should fall within the claims appended to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the filler surface before surface etching advances, and the filler surface after surface etching.

Claims (5)

As a flexible substrate for display containing inorganic particle filler used for flat displays, such as a liquid crystal display, an organic EL display, a plasma display panel, an electronic paper, At least one heat resistant resin selected from polyethylenenaphthalate, polyethersulfone, polyimide, polyethyleneterephthalate, polyarylate, and polycarbonate, and At least one inorganic particle filler selected from silicon dioxide (SiO 2), barium sulfate (BaSO ₄ ), boehmite and wollastonite having an aspect ratio of 1 to 3,000, The inorganic particle filler is contained 5 to 50wt% based on the total weight of the mixture of the heat resistant resin and the inorganic particle filler, The inorganic particle filler is a flexible substrate for a display containing an inorganic particle filler, characterized in that the surface is etched. The method of claim 1, The inorganic particle filler is a flexible substrate for display having a linear expansion coefficient of 0.5 ~ 7 CTE (ppm / ℃). delete The method according to claim 1 or 2, The heat-resistant resin is a polyarylate, the flexible substrate for a display containing an inorganic particle filler. The method according to claim 1 or 2, The inorganic particle filler is a flexible substrate for a display containing an inorganic particle filler, characterized in that the wollastonite.

Images