JP2006039331A - Plastic substrate for display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic substrate for a display element, the substrate having excellent heat resistance and transparency. <P>SOLUTION: The plastic substrate for a display element contains as a structural component, epoxy resin which is a compound (a) having two or more epoxy groups and which has ≥85% purity calculated from oxirane oxygen concentration (measured oxirane oxygen concentration/proportion of oxirane oxygen in the structural formula×100). The compound (a) having two or more epoxy groups is preferably an alicyclic epoxy resin or a hydrogenated biphenyl alicyclic epoxy resin, and the resin is preferably cured with a cationic curative system catalyst. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plastic substrate for display elements having excellent heat resistance and transparency.

In recent years, liquid crystal display devices have high demands such as thinning, lightening, large size, and curved display. Especially for portable devices, weight reduction and high durability are strongly demanded, and as these uses are expanded, liquid crystal display panels using transparent plastic substrates instead of conventional glass substrates are being studied. It began to be put into practical use.
Resin used for the plastic substrate for display elements is, for example, a composition comprising an alicyclic epoxy resin, an acid anhydride curing agent, alcohol and a curing catalyst in Patent Document 1, and an alicyclic epoxy resin and alcohol in Patent Document 2. A resin composition comprising an acid anhydride-based curing agent partially esterified with a curing catalyst and a curing catalyst, Patent Document 3 discloses a resin composition comprising an alicyclic epoxy resin, an acid anhydride-based curing agent having a carboxylic acid, and a curing catalyst. It is shown. However, the conventional display element substrate resins shown in these documents have high transparency, but have a glass transition temperature of 200 ° C. or lower, and when a high temperature process is required, the strength and elastic modulus of the substrate at high temperatures are poor. There was a possibility that the substrate was deformed sufficiently.

JP-A-6-337408 JP 2001-59015 A JP 2001-59014 A

  An object of this invention is to provide the plastic substrate for display elements with high heat resistance and transparency.

  The present inventors diligently studied to achieve the above problems. As a result, a plastic substrate for a display element comprising a compound (a) having two or more epoxy groups and an epoxy resin having a purity of 85% or more determined from the oxirane oxygen concentration as a constituent component is a liquid crystal display element, a color It has been found that it can be suitably used for display elements such as filters, organic EL display elements, and electronic paper, and has completed the present invention.

（３） 前記２つ以上のエポキシ基を有する化合物（ａ）が下記化学式（２）で示される脂環式エポキシ樹脂である（１）の表示素子用プラスチック基板、

（４） カチオン硬化系触媒（ｂ）で硬化した（１）〜（３）いずれかの表示素子用プラスチック基板、
（５） 前記カチオン系硬化触媒（ｂ）が、加熱によりカチオン重合を開始させる物質を放出する開始剤であり、芳香族スルホニウム塩、芳香族ヨードニウム塩、アルミニウムキレートから選ばれた1種以上である（１）〜（４）の表示素子基板用エポキシ樹脂組成物
、
（６） ガラス転移温度が２００℃以上であり、かつ波長４００ｎｍ以上における光線透過率が８０％以上であるである（１）〜（５）いずれかの表示素子用プラスチック基板、である。 That is, the present invention provides (1) a plastic substrate for a display element, which is a compound (a) having two or more epoxy groups, and contains an epoxy resin having a purity of 85% or more determined from the oxirane oxygen concentration as a constituent component,
(2) The plastic substrate for a display element according to (1), wherein the compound (a) having two or more epoxy groups is an alicyclic epoxy resin represented by the following chemical formula (1):

(3) The plastic substrate for a display element according to (1), wherein the compound (a) having two or more epoxy groups is an alicyclic epoxy resin represented by the following chemical formula (2):

(4) The plastic substrate for a display element according to any one of (1) to (3) cured with a cationic curing catalyst (b),
(5) The cationic curing catalyst (b) is an initiator that releases a substance that initiates cationic polymerization by heating, and is at least one selected from aromatic sulfonium salts, aromatic iodonium salts, and aluminum chelates. (1) to (4) epoxy resin composition for display element substrate,
(6) The plastic substrate for a display element according to any one of (1) to (5), wherein the glass transition temperature is 200 ° C. or higher and the light transmittance at a wavelength of 400 nm or higher is 80% or higher.

  The plastic substrate for display element of the present invention is excellent in heat resistance and transparency, and can be suitably used for a liquid crystal display element plastic substrate, a color filter substrate, an organic EL substrate, a touch panel, electronic paper, and the like.

Hereinafter, the present invention will be described in detail.
The epoxy resin used in the present invention is a compound (a) having two or more epoxy groups, and the purity determined from the oxirane oxygen concentration is 85% or more. Preferably, it is 90% or more, more preferably 92% or more, and most preferably 95% or more. Here, the purity obtained from the oxirane oxygen concentration can be obtained by (measured value of oxirane oxygen concentration) / (ratio of oxirane oxygen in the structural formula) × 100. The oxirane oxygen concentration can be measured according to ASTM-1652. The present inventors have found that when a plastic substrate for a display element is prepared using an epoxy resin having a purity of 85% or less determined from the oxirane oxygen concentration, the heat resistance and chemical resistance are inferior, which is not preferable.
A preferable example of the compound (a) having two or more epoxy groups is not particularly limited, but an alicyclic epoxy resin is preferable because it has heat resistance and transparency suitable for a plastic substrate for display elements. Among them, the alicyclic epoxy resin represented by the general formula (1) and the hydrogenated biphenyl type alicyclic epoxy resin represented by the general formula (2) are more preferable, and the alicyclic represented by the general formula (1). Among epoxy resins, 2,2-bis (3 ′, 4 ′) in which X is —C (CH ₃ ) ₂ —
-Epoxycyclohexyl) propane is more preferred.

  Examples of the cationic curing catalyst (b) used in the present invention include an initiator that releases a substance that initiates cationic polymerization by heating, an initiator that releases a substance that initiates cationic polymerization by active energy rays, and the like. Since a cured product having high heat resistance is obtained, an initiator that releases a substance that initiates cationic polymerization by heating, that is, a thermal cationic curing catalyst is preferable.

  Preferred thermal cation curing catalysts include aromatic sulfonium salts, aromatic iodonium salts, aluminum chelates and the like. Specific examples of the aromatic sulfonium salt include SI-60L, SI-80L, SI-100L manufactured by Sanshin Chemical Industry, CP-66 and CP-77 manufactured by Asahi Denka Kogyo Co., Ltd. Is Daicel Chemical Industries' DAICAT EX-1.

  When the plastic substrate for a display element of the present invention is used as a substrate for a liquid crystal display element, a substrate for a color filter, a plastic substrate for an organic EL display element, a solar cell substrate, a touch panel substrate, an electronic paper substrate, etc. The glass transition temperature is preferably 200 ° C. or higher, and the light transmittance at a wavelength of 400 nm is preferably 80% or higher. If the thickness of the substrate is within this range, the flatness is excellent, and the weight of the substrate can be reduced as compared with the glass substrate. The glass transition temperature is more preferably 220 ° C. or higher, and most preferably 250 ° C. or higher. If the glass transition temperature is 200 ° C. or lower, in a high-temperature process, the strength and elastic modulus of the substrate at a high temperature may decrease, and the substrate may be deformed. The light transmittance at a wavelength of 400 nm is more preferably 85% or more. When the light transmittance at a wavelength of 400 nm is 80% or less, coloring tends to be observed, which is not preferable.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated in detail by an Example, this invention is not limited to the following examples, unless the summary is exceeded.

Example 1
100 parts by weight of hydrogenated biphenyl type alicyclic epoxy resin (E-BP) having a purity determined from oxirane oxygen concentration of 87% and 1 part by weight of an aromatic sulfonium-based thermal cation catalyst (SI-100L, manufactured by Sanshin Chemical Industry) Were melt-mixed and cured at 80 ° C./2 h and 200 ° C./2 h to obtain a sheet having a thickness of 300 μm.
(Example 2)
An aromatic sulfonium-based thermal cation catalyst (manufactured by Sanshin Chemical Industry Co., Ltd.) was added to 100 parts by weight of 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane (E-DOA) having a purity determined from the oxirane oxygen concentration of 95%. (SI-100L) 1 part by weight was melt-mixed and cured at 80 ° C./2 h and 250 ° C./2 h to obtain a sheet having a thickness of 300 μm.
(Example 3)
An aromatic sulfonium-based thermal cation catalyst (manufactured by Sanshin Chemical Industry Co., Ltd.) was added to 100 parts by weight of 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane (E-DOA) having a purity determined from oxirane oxygen concentration of 98%. (SI-100L) 1 part by weight was melt-mixed and cured at 80 ° C./2 h and 250 ° C./2 h to obtain a sheet having a thickness of 300 μm.

(Comparative Example 1)
An aromatic sulfonium-based thermal cation catalyst (manufactured by Sanshin Chemical Industry Co., Ltd.) was added to 100 parts by weight of 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane (E-DOA) having a purity determined from the oxirane oxygen concentration of 80%. (SI-100L) 1 part by weight was melt-mixed and cured at 80 ° C./2 h and 250 ° C./2 h to obtain a sheet having a thickness of 300 μm.
About the optical sheet produced as mentioned above, various characteristics were measured by the evaluation method shown below.

The formulations and results of Examples and Comparative Examples are shown in Tables 1 and 2, respectively.
a) Heat resistance (Tg)
Measured with a DMS-210 viscoelasticity measuring device manufactured by Seiko Electronics Co., Ltd., and the maximum value of tan δ at 1 Hz was defined as the glass transition temperature (Tg).
b) Light transmittance The light transmittance at 400 nm and 550 nm was measured with a spectrophotometer U3200 (manufactured by Shimadzu Corporation).

  The plastic substrates for display elements of Examples 1, 2, and 3 comprising an epoxy resin having a purity determined from the oxirane oxygen concentration of 85% or higher have a glass transition temperature of 250 ° C. or higher and a light transmittance of 85% or higher, Excellent heat resistance and transparency. On the other hand, in Comparative Example-1 having a purity of 80%, the glass transition temperature was 200 ° C. or lower, and the heat resistance was inferior to that of the Examples.

  The epoxy resin composition of the present invention can be suitably used for a liquid crystal display element plastic substrate, a color filter substrate, an organic EL display element plastic substrate, a touch panel, electronic paper, and the like.

Claims (6)

A plastic substrate for a display element, comprising a compound (a) having two or more epoxy groups and having an epoxy resin having a purity of 85% or more determined from an oxirane oxygen concentration as a constituent component. The plastic substrate for a display element according to claim 1, wherein the compound (a) having two or more epoxy groups is an alicyclic epoxy resin represented by the following chemical formula (1).

The plastic substrate for a display element according to claim 1, wherein the compound (a) having two or more epoxy groups is an alicyclic epoxy resin represented by the following chemical formula (2).

The plastic substrate for display elements according to any one of claims 1 to 3, which is cured with a cationic curing catalyst (b). The cationic curing catalyst (b) is an initiator that releases a substance that initiates cationic polymerization by active energy rays and / or heating, and is selected from aromatic sulfonium salts, aromatic iodonium salts, and aluminum chelates. It is the above, The plastic substrate for display elements in any one of Claims 1-4. The glass substrate has a glass transition temperature of 200 ° C. or higher, and has a light transmittance of 80% or higher at a wavelength of 400 nm.