JP5716854B2 - Heat-resistant transparent plastic substrate for flat panel displays - Google Patents

Description

  The present invention relates to a heat-resistant transparent plastic substrate, and more particularly to a heat-resistant transparent plastic substrate for flat panel displays having excellent optical properties and mechanical properties.

  Flat panel displays typified by liquid crystal displays, organic EL displays, plasma displays, and electronic paper make use of features such as thinness, lightness, and low power consumption, flat-screen TVs, computer monitors, notebook computers, mobile phones, cars It is growing rapidly as a display element for navigation. Conventionally, glass substrates have been used as substrates for these display elements. However, the glass substrate has high specific gravity and thus has problems such as being heavy, weak in impact strength and easily cracked, difficult to thin, and lack of flexibility. Development of displays using plastic substrates, mainly for liquid crystal displays, organic EL displays, and electronic paper, because it is possible to reduce the thickness and weight by using plastics for substrates, and further expansion to flexible displays can be expected. Is energetically advanced.

  However, in the manufacturing process of a liquid crystal display, an organic EL display, and electronic paper, in many processes such as a thin film transistor (hereinafter referred to as TFT) forming process, a panel bonding process, an alignment film forming process, and a transparent electrode forming process, 150 A high process temperature from ℃ to 200 ℃ or higher is required. Therefore, high heat resistance is required for the display substrate. In addition, since the demand for display characteristics of displays is becoming stricter year by year, excellent optical characteristics are also demanded for display substrates.

  Polycarbonate (hereinafter referred to as PC) is known as a typical heat-resistant transparent plastic, but PC has a glass transition temperature of around 150 ° C. and is used for display substrates, particularly for active displays using TFTs. As a substrate, there is a big problem in heat resistance. Polyether sulfone (hereinafter referred to as PES) is a highly heat-resistant transparent plastic. Although PES has heat resistance of 180 ° C., PES is colored from light yellow to brown, and has problems in color tone and transparency. There are also problems with optical properties such as a large photoelastic constant, birefringence (optical anisotropy) caused by slight stress and strain, and a large wavelength dependence of the refractive index. The characteristics are not fully satisfied.

  The wholly aromatic polyimide has high heat resistance of 300 ° C. or higher, but has a problem in optical properties such as having a dark brown color.

  On the other hand, a high polymer comprising a fumaric acid diester was found by Otsu et al. In 1981 (see, for example, Non-Patent Document 1), and many reports have been made on the polymerization behavior of fumaric acid diester (for example, Non-Patent Document). 2). An optical material made of a fumaric acid diester polymer is disclosed, and an optical lens, a prism lens, and an optical fiber are described (see Patent Document 1). However, these documents do not disclose a heat-resistant transparent plastic substrate for display according to the present invention.

  Moreover, the use as a modifier of a vinyl-type polymer is disclosed (refer patent document 2), and the acrylate-based polymer composite is disclosed (refer patent document 3). However, these are vinyl polymer modifiers, and a heat-resistant transparent plastic substrate is not disclosed.

  We have found that a plastic substrate and a display element made of a specific fumaric acid diester resin have excellent heat resistance and transparency (see Patent Document 4).

  However, the plastic substrate made of the fumaric acid diester resin described in Patent Document 4 has a problem that the retardation in the film in-plane direction is small, but the retardation in the film thickness direction is large. Further, further improvement in mechanical strength is desired from the viewpoint of handling in the display manufacturing process.

Japanese Patent Laid-Open No. 61-028513 JP 59-109547 A JP-A-61-181812 JP 2005-97544 A

Polymer Preprints, Japan, 30, 832 (1981) Radical polymerization handbook (159 pages), ST

  An object of the present invention is to provide a heat-resistant transparent plastic substrate for display having a small retardation in the film thickness direction, excellent optical characteristics, and excellent mechanical characteristics.

As a result of intensive studies in view of the above problems, the present inventors have found that a heat-resistant transparent plastic substrate containing a fumaric acid diester polymer and an acrylate polymer has a small phase difference in the film thickness direction and excellent mechanical properties. As a result, the present invention has been completed. That is, the present invention relates to a fumaric acid diester polymer (A) containing a fumaric acid diester residue unit represented by a predetermined general formula and a number average molecular weight (Mn) containing an acrylic ester residue unit represented by a predetermined general formula. ) Contains 1 × 10 ^{4 to} 5 × 10 ⁵ acrylate polymer (B), which is a heat-resistant transparent plastic substrate for flat panel displays.

  Hereinafter, the present invention will be described in more detail.

The heat-resistant transparent plastic substrate for flat panel display of the present invention (hereinafter sometimes abbreviated as heat-resistant transparent plastic substrate) is a fumaric acid diester polymer containing a fumaric acid diester residue unit represented by the following general formula (1) ( A) and an acrylic ester polymer (B) having a number average molecular weight (Mn) of 1 × 10 ^{4 to} 5 × 10 ⁵ including an acrylic ester residue unit represented by the following general formula (2). is there.

（式中、Ｒ_１、Ｒ_２はそれぞれ独立して炭素数３〜１２の分岐状アルキル基又は環状アルキル基を示す。）

(In formula, R < ₁ >, R < ₂ > shows a C3-C12 branched alkyl group or cyclic alkyl group each independently.)

（式中、Ｒ_３は炭素数１〜１２のアルキル基又は環状アルキル基を示す。）
本発明の耐熱透明プラスチック基板に含有されるフマル酸ジエステル重合体（Ａ）は、一般式（１）で示されるフマル酸ジエステル残基単位を含むものである。ここで、フマル酸ジエステル残基単位のエステル置換基であるＲ_１、Ｒ_２は、それぞれ独立して炭素数３〜１２の分岐状アルキル基又は環状アルキル基であり、例えば、イソプロピル基、ｓ−ブチル基、ｔ−ブチル基、ｓ−ペンチル基、ｔ−ペンチル基、ｓ−ヘキシル基、ｔ−ヘキシル基、シクロプロピル基、シクロペンチル基、シクロヘキシル基等が挙げられ、特に耐熱性、機械特性に優れたものとなることからイソプロピル基、ｓ−ブチル基、ｔ−ブチル基、シクロペンチル基、シクロヘキシル基であることが好ましく、特に耐熱性、機械特性のバランスに優れたものとなることからイソプロピル基が好ましい。ここで、Ｒ_１又はＲ_２が直鎖アルキルの場合、又は、炭素数が１２を越える場合、フマル酸ジエステル系樹脂のガラス転移温度が低いものとなり、プラスチック基板の耐熱性が低下したり、機械特性が低いものとなる。一般式（１）で示されるフマル酸ジエステル残基単位としては、具体的には、フマル酸ジイソプロピル残基、フマル酸ジ−ｓ−ブチル残基、フマル酸ジ−ｔ−ブチル残基、フマル酸ジ−ｓ−ペンチル残基、フマル酸ジ−ｔ−ペンチル残基、フマル酸ジ−ｓ−ヘキシル残基、フマル酸ジ−ｔ−ヘキシル残基、フマル酸ジ−２−エチルヘキシル、フマル酸ジシクロプロピル残基、フマル酸ジシクロペンチル残基、フマル酸ジシクロヘキシル残基等が挙げられ、フマル酸ジイソプロピル残基、フマル酸ジ−ｓ−ブチル残基、フマル酸ジ−ｔ−ブチル残基、フマル酸ジシクロペンチル残基、フマル酸ジシクロヘキシル残基が好ましく、特にフマル酸ジイソプロピル残基が好ましい。

(In the formula, R ₃ represents an alkyl group having 1 to 12 carbon atoms or a cyclic alkyl group.)
The fumaric acid diester polymer (A) contained in the heat-resistant transparent plastic substrate of the present invention contains a fumaric acid diester residue unit represented by the general formula (1). Here, R ₁ and R ₂ which are ester substituents of the fumaric acid diester residue unit are each independently a branched alkyl group or cyclic alkyl group having 3 to 12 carbon atoms, such as isopropyl group, s- Examples include butyl group, t-butyl group, s-pentyl group, t-pentyl group, s-hexyl group, t-hexyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group and the like, and particularly excellent in heat resistance and mechanical properties. Therefore, an isopropyl group, a s-butyl group, a t-butyl group, a cyclopentyl group, and a cyclohexyl group are preferable, and an isopropyl group is particularly preferable because it has an excellent balance of heat resistance and mechanical properties. . Here, when R ₁ or R ₂ is linear alkyl, or when the number of carbon atoms exceeds 12, the glass transition temperature of the fumaric acid diester resin becomes low, and the heat resistance of the plastic substrate decreases, The characteristics are low. As the fumaric acid diester residue unit represented by the general formula (1), specifically, diisopropyl fumarate residue, di-s-butyl fumarate residue, di-t-butyl fumarate residue, fumaric acid Di-s-pentyl residue, di-t-pentyl fumarate residue, di-s-hexyl fumarate residue, di-t-hexyl fumarate residue, di-2-ethylhexyl fumarate, dicyclofumarate Propyl residue, dicyclopentyl fumarate residue, dicyclohexyl fumarate residue, and the like. Diisopropyl fumarate residue, di-s-butyl fumarate residue, di-t-butyl fumarate residue, di-fumarate A cyclopentyl residue and a dicyclohexyl fumarate residue are preferred, and a diisopropyl fumarate residue is particularly preferred.

  The fumaric acid diester polymer (A) contains a fumaric acid diester residue unit represented by the general formula (1), but the fumaric acid represented by the general formula (1) is a plastic substrate having good heat resistance. A polymer containing 60 mol% or more of diester residue units and 40 mol% or less of residue units copolymerizable with fumaric acid diesters is preferred, and 60 to 90 mol of fumaric acid diester residue units represented by the general formula (1) %, A polymer containing 10 to 40 mol% of a residue unit copolymerizable with fumaric acid diesters is more preferable.

  Examples of the residue unit copolymerizable with fumaric acid diesters include fumaric acid having linear alkyl such as diethyl fumarate residue, di-n-propyl fumarate residue, and fumarate-n-butyl residue. Styrene residues such as ester residues, styrene residues and α-methylstyrene residues; acrylic acid residues; acrylic acid ester residues such as methyl acrylate residues, ethyl acrylate residues and butyl acrylate residues Groups: methacrylic acid residues; methacrylic acid ester residues such as methyl methacrylate residue, ethyl methacrylate residue and butyl methacrylate residue; vinyl ester residues such as vinyl acetate residue and vinyl propionate residue Acrylonitrile residue; methacrylonitrile residue; one or more of olefin residues such as ethylene residue and propylene residue Door can be. Among these, since a plastic substrate having good compatibility and small haze can be obtained, linear alkyl such as diethyl fumarate residue, di-n-propyl fumarate residue, and n-butyl fumarate residue can be used. The fumaric acid ester residue is preferred.

The fumaric acid diester polymer (A) is obtained from an elution curve measured by gel permeation chromatography (hereinafter referred to as GPC) in order to maintain the mechanical strength and surface properties of the resulting heat-resistant transparent plastic substrate. the number average molecular weight of standard polystyrene (Mn) of preferably 1 ^× 10 3 ~5 × 10 ⁶ to be particularly excellent in mechanical properties, since it becomes excellent in moldability during film 1 × 10 ⁴ ~ 2 × 10 ⁵ is preferable.

  The fumaric acid diester polymer (A) may be produced by any method as long as the fumaric acid diester polymer can be obtained. For example, the fumaric acid diester polymer may be co-polymerized with fumaric acid diesters and, in some cases, fumaric acid diesters. It can be produced by carrying out radical polymerization using a polymerizable monomer in combination. Examples of fumaric acid diesters include diisopropyl fumarate, di-s-butyl fumarate, di-t-butyl fumarate, di-s-pentyl fumarate, di-t-pentyl fumarate, and fumaric acid. Examples include di-s-hexyl, di-t-hexyl fumarate, di-2-ethylhexyl fumarate, dicyclopropyl fumarate, dicyclopentyl fumarate, dicyclohexyl fumarate, and the like. Examples of the monomer include styrenes such as diethyl fumarate, di-n-propyl fumarate, di-n-butyl fumarate, styrene, and α-methylstyrene; acrylic acid; methyl acrylate, ethyl acrylate, acrylic Acrylic acid esters such as butyl acid; methacrylic acid; methyl methacrylate, ethyl methacrylate, methacrylate Methacrylic acid esters such as Le butyl; vinyl acetate, vinyl esters such as vinyl propionate; acrylonitrile; methacrylonitrile; ethylene, can be exemplified one or two or more of such olefins such as propylene.

  In addition, as a radical polymerization method for polymerizing these monomers, a known polymerization method may be used. For example, any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, and an emulsion polymerization method may be used. Can be adopted.

  Examples of the polymerization initiator used in the radical polymerization method include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, and dicumyl peroxide. Organic peroxides such as oxide, t-butylperoxyacetate, t-butylperoxybenzoate; 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-butyronitrile), Examples thereof include azo initiators such as 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, and 1,1′-azobis (cyclohexane-1-carbonitrile).

  And there is no restriction | limiting in particular as a solvent which can be used in a solution polymerization method or a precipitation polymerization method, For example, aromatic solvents, such as benzene, toluene, xylene; Alcohol solvents, such as methanol, ethanol, propyl alcohol, and butyl alcohol; Cyclohexane; Dioxane; tetrahydrofuran; acetone; methyl ethyl ketone; dimethylformamide; isopropyl acetate; and a mixed solvent thereof.

  Moreover, the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of a polymerization initiator, and generally it is preferable to carry out in the range of 30-150 degreeC.

The acrylate polymer (B) contained in the heat-resistant transparent plastic substrate of the present invention contains an acrylate residue unit represented by the general formula (2). Here, R ₃ which is an ester substituent of the acrylate residue unit is an alkyl group having 1 to 12 carbon atoms or a cyclic alkyl group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, n- Butyl group, isobutyl group, t-butyl group, n-pentyl group, s-pentyl group, t-pentyl group, n-hexyl group, s-hexyl group, t-hexyl group, cyclohexyl group, 2-ethylhexyl group, lauryl In particular, an ethyl group, an n-butyl group, and an n-hexyl group are preferable because of being excellent in heat resistance and mechanical properties, and ethyl is particularly excellent in transparency. Groups are preferred. Specific examples of the acrylate residue unit represented by the general formula (2) include methyl acrylate residue, ethyl acrylate residue, propyl acrylate residue, isopropyl acrylate residue, acrylic acid-n. -Butyl residue, isobutyl acrylate residue, acrylic acid-t-butyl residue, acrylic acid-s-pentyl residue, acrylic acid-t-pentyl residue, acrylic acid-n-hexyl residue, acrylic acid- s-hexyl residue, cyclohexyl acrylate residue and the like can be mentioned. Ethyl acrylate residue, acrylate-n-butyl residue, acrylate-n-hexyl residue are preferable, and ethyl acrylate residue is particularly preferable. .

  The acrylic acid ester polymer (B) contains an acrylic acid ester residue unit represented by the general formula (2), but has excellent transparency, so that the acrylic acid ester residue unit 60 represented by the general formula (2) is used. Preferably, it contains at least mol%, more preferably at least 75 mol%. Moreover, it is also preferable that 60 mol% or more of acrylate residue units represented by the general formula (2) and 40 mol% or less of residue units copolymerizable with acrylate esters are included. Residue units copolymerizable with acrylic esters include, for example, styrene residues such as styrene residues and α-methylstyrene residues; methacrylic acid residues; methyl methacrylate residues and ethyl methacrylate residues. Methacrylic acid ester residues such as butyl methacrylate residue; vinyl ester residues such as vinyl acetate residue and vinyl propionate residue; acrylonitrile residue; methacrylonitrile residue; ethylene residue, propylene residue 1 type, or 2 or more types, such as olefin residues, etc. can be mentioned.

In order to maintain the mechanical strength and heat resistance of the resulting heat-resistant transparent plastic substrate, the acrylic acid ester polymer (B) has a number average molecular weight (Mn) of 1 × 10 in terms of standard polystyrene obtained from an elution curve measured by GPC. ³ to 1 × 10 ⁷ is preferable, and it is particularly preferably 1 × 10 ^{4 to} 5 × 10 ⁵ because it has excellent mechanical properties and excellent moldability during film formation. The present invention is characterized in that the acrylic ester polymer (B) has a number average molecular weight (Mn) of 1 × 10 ^{4 to} 5 × 10 ⁵ .

  The acrylate polymer (B) may be produced by any method as long as the acrylate polymer is obtained. For example, the acrylate polymer (B) may be produced together with acrylate esters and, in some cases, acrylate esters. It can be produced by carrying out radical polymerization using a polymerizable monomer in combination. Examples of the acrylic acid esters at this time include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, acrylic acid-n-butyl, acrylic acid isobutyl, acrylic acid-t-butyl, and acrylic acid-s. -Pentyl, acrylic acid-t-pentyl, acrylic acid-n-hexyl, acrylic acid-s-hexyl, cyclohexyl acrylate, etc., and examples of the monomer copolymerizable with acrylic acid ester include styrenes , Methacrylic acid esters, vinyl esters, acrylonitrile, olefins and the like.

  In addition, as a radical polymerization method for polymerizing these monomers, a known polymerization method may be used. For example, any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, and an emulsion polymerization method may be used. Can be adopted.

  Examples of the polymerization initiator used in the radical polymerization method include the organic peroxides and azo initiators described above.

  And there is no restriction | limiting in particular as a solvent which can be used in a solution polymerization method or a precipitation polymerization method, For example, an aromatic solvent, an alcohol solvent, a ketone solvent, an ether solvent, an acetate solvent, a dimethylformamide, etc. are mentioned, These mixed solvents are also included.

  Moreover, the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of a polymerization initiator, and generally it is preferable to carry out in the range of 30-150 degreeC.

  The ratio of the fumaric acid diester polymer (A) and the acrylate polymer (B) contained in the heat-resistant transparent plastic substrate of the present invention is not particularly limited, but the heat resistance of the resulting heat-resistant transparent plastic substrate is In order to maintain the retardation in the thickness direction, 60 to 99% by weight of the fumaric acid diester polymer (A) and 1 to 40% by weight of the acrylic acid ester polymer (B) are preferable, and particularly the fumaric acid diester polymer (A) 75. -95 weight% and acrylic acid ester polymer (B) 5-25 weight% are preferable.

  The heat-resistant transparent plastic substrate of the present invention preferably has a thickness of 10 to 200 μm, more preferably 30 to 100 μm, in order to maintain the retardation and mechanical properties in the substrate thickness direction.

  The heat-resistant transparent plastic substrate of the present invention has a zero viewing angle difference in the substrate thickness direction in order to prevent defects in viewing angle characteristics when the display is used (for example, a decrease in contrast or color shift when the display is viewed obliquely). ˜−200 nm is preferable, more preferably 0 to −150 nm, and particularly preferably 0 to −100 nm. The retardation (Rth) in the thickness direction of the substrate is expressed by Expression (1). Here, nx is the refractive index in the in-plane direction of the substrate, ny is the refractive index in the in-plane direction of the substrate orthogonal to nx, nz is the refractive index in the substrate thickness direction, and d is the thickness of the substrate. As the retardation (Rth) in the substrate thickness direction, a value measured using a fully automatic birefringence meter (manufactured by Oji Scientific Instruments, trade name: KOBRA-21ADH) under a measurement wavelength of 589 nm was used.

Rth = [(nx + ny) / 2−nz] xd (1)
In the heat-resistant transparent plastic substrate of the present invention, the haze is preferably 2% or less, and more preferably 1% or less in order to maintain image quality, particularly contrast, when used in a display.

  As the method for producing the heat-resistant transparent plastic substrate of the present invention, any method may be used as long as the heat-resistant transparent plastic substrate of the present invention can be produced. The heat-resistant transparent plastic having excellent optical properties, heat resistance, surface properties, etc. Since a substrate is obtained, it is preferable to manufacture by a solution casting method. Here, the solution casting method is a method of obtaining a plastic substrate by casting a resin solution (generally referred to as a dope) on a supporting substrate and then evaporating the solvent by heating. As a casting method, for example, a T-die method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method, or the like is used. The method of continuous extrusion is most commonly used. Examples of the support substrate used include a glass substrate, a metal substrate such as stainless steel and ferrotype, and a plastic substrate such as polyethylene terephthalate. In order to industrially continuously form a substrate having high surface properties and optical homogeneity, a metal substrate having a mirror-finished surface is preferably used. In the solution casting method, the viscosity of the resin solution is an extremely important factor when producing a heat-resistant transparent plastic substrate with excellent thickness accuracy and surface smoothness. The viscosity of the resin solution is the resin concentration, molecular weight, solvent It depends on the type. The resin solution for producing the heat-resistant transparent plastic substrate of the present invention is prepared by dissolving the fumaric acid diester polymer (A) and the acrylic acid ester polymer (B) in a solvent. The viscosity of the resin solution can be adjusted by the molecular weight of the polymer, the concentration of the polymer, and the type of solvent. The viscosity of the resin solution is preferably 100 to 10000 cps, more preferably 500 to 5000 cps, and particularly preferably 1000 to 3000 cps.

  Moreover, the heat-resistant transparent plastic substrate of this invention can be laminated | stacked with the film which consists of other resin as needed. Examples of other resins include polyether sulfone, polyarylate, polyethylene terephthalate, polynaphthalene terephthalate, polycarbonate, cyclic polyolefin, maleimide resin, fluorine resin, polyimide, and the like. It is also possible to laminate a hard coat layer or a gas barrier layer. Examples of the hard coat layer include layers of silicon resin, acrylic resin, acrylic silicon resin, ultraviolet curable resin, urethane hard coat agent, and the like, and these can be used in one or more kinds. . From the viewpoints of transparency, scratch resistance, and chemical resistance, an ultraviolet curable resin is preferable. Examples of the ultraviolet curable resin include one or more ultraviolet curable resins selected from ultraviolet curable acrylic urethane, ultraviolet curable epoxy acrylate, ultraviolet curable (poly) ester acrylate, ultraviolet curable oxetane, and the like. The thickness of the hard coat layer is preferably 0.1 to 100 μm, more preferably 1 to 50 μm, and particularly preferably 2 to 20 μm in order to maintain scratch resistance, film surface properties, and the like.

  Examples of the gas barrier layer include inorganic layers such as silicon oxide, silicon nitride, silicon nitride oxide, aluminum oxide, tantalum oxide, and aluminum film; and organic film layers such as polyvinyl alcohol and polyolefin. A material mainly composed of silicon oxide, silicon nitride, or silicon nitride oxide is preferable because of excellent gas barrier performance and dimensional stability which is important for high-definition displays. In the case of an inorganic film, the thickness of the gas barrier layer is preferably 1 nm to 1000 nm, more preferably 10 nm to 300 nm, because the film formation and gas barrier properties are good. In the case of an organic layer, the coating property is good. Therefore, the thickness is preferably 0.1 μm to 100 μm, more preferably 1 μm to 50 μm. These gas barrier layers can be formed by laminating an organic layer and an inorganic layer. The gas barrier layer can be formed by a known method such as vapor deposition, sputtering, PECVD, CatCVD, coating or laminating.

  The heat-resistant transparent plastic substrate of the present invention preferably contains an antioxidant in order to improve thermal stability. Examples of the antioxidant include hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, lactone antioxidants, amine-based antioxidants, hydroxylamine-based antioxidants, and vitamin E-based agents. Antioxidants and other antioxidants may be mentioned, and these antioxidants may be used alone or in combination. For improving the thermal stability, a phenolic antioxidant is preferable. Further, it is preferable to use a hindered phenolic antioxidant and a phosphorus antioxidant in combination from the viewpoint of thermal coloring. For example, it is particularly preferable to use a phosphoric antioxidant in a ratio of 0 to 1000 parts by weight, particularly 100 to 500 parts by weight, with respect to 100 parts by weight of the hindered phenolic antioxidant. Further, the amount of the antioxidant added is 100% by weight of a fumaric acid diester resin because it is excellent in thermal stability and heat-resistant coloring when exposed to high temperatures, and there is no possibility of occurrence of substrate surface roughness, bleeding, haze deterioration, etc. The amount is preferably from 0.01 to 10 parts by weight, particularly preferably from 0.5 to 3.0 parts by weight, based on the part.

  In addition, the heat-resistant transparent plastic substrate of the present invention may contain a hindered amine light stabilizer, and the hindered amine light stabilizer has a molecular weight of 1000 because it becomes a plastic substrate for a display excellent in thermal coloring suppression effect. The above are preferable, and 1500 or more are particularly preferable. Further, the amount of the hindered amine light stabilizer added is 0.01 to 1.5 with respect to 100 parts by weight of the fumaric acid diester polymer because it becomes a plastic substrate for display excellent in thermal coloring prevention effect and light stabilization effect. It is preferable to use parts by weight, more preferably 0.05 to 1 part by weight, and particularly preferably 0.1 to 0.5 part by weight. Examples of such a hindered amine light stabilizer include poly ((6-morpholino-s-triazine-2,4-diyl) ((2,2,6,6-tetramethyl-4-piperidyl) imino) hexa. Methylene ((2,2,6,6-tetramethyl-4-piperidyl) imino)) (molecular weight 1,600), poly ((6- (1,1,3,3-tetramethylbutyl) amino-1, 3,5-triazine-2,4-diyl) ((2,2,6,6-tetramethyl-4-piperidyl) imino) hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) Imino)) (molecular weight 2,000-3,100), dibutylamine-1,3,5-triazine-N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) -1, 6-hexamethylenediamine and -(2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate (molecular weight 2,600-3,400), N, N'-bis (3-aminopropyl) ethylenediamine-2,4 -Bis (N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -6-chloro-1,3,5-triazine condensate (molecular weight 2,000 or more), Examples thereof include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine condensate (molecular weight 3,100 to 4,000) and the like. Can be used.

  The heat-resistant transparent plastic substrate for display of the present invention may contain an ultraviolet absorber for the purpose of preventing deterioration of the liquid crystal compound. Examples of the ultraviolet absorber include benzotriazole, benzophenone, triazine, and benzoate. The ultraviolet absorber may be added as necessary.

  Further, the heat-resistant transparent plastic substrate of the present invention is within the range where the effects of the invention are exerted, other polymers, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, pigments, dyes, antistatic agents, antiblocking agents, lubricants. Etc. may be contained.

  Since the heat-resistant transparent plastic substrate of the present invention has a small retardation in the thickness direction of the substrate and exhibits good mechanical properties, a liquid crystal display, an organic EL display, a plastic substrate for electronic paper such as a microcapsule method and an electronic powder flow method, etc. Useful as.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

  In addition, the various physical properties shown by an Example were measured with the following method.

<Analysis of polymer>
The composition of the copolymer was determined by proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) spectrum analysis using a nuclear magnetic resonance measuring apparatus (manufactured by JEOL, trade name: JNM-GX270).

<Measurement of number average molecular weight>
Using a gel permeation chromatography (GPC) apparatus (manufactured by Tosoh Corporation, trade name: C0-8011 (equipped with column GMH _HR- H)), tetrahydrofuran was measured at 40 ° C. and obtained as a standard polystyrene equivalent value. It was.

<Measurement of light transmittance and haze of plastic substrate>
The light transmittance and haze of the film produced were measured using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.). The light transmittance was measured according to JIS K 7361-1 (1997 edition). Measurements were made in accordance with JIS-K 7136 (2000 version).

<Measurement of thickness direction retardation (Rth) of plastic substrate>
Using a sample tilt type automatic birefringence meter (manufactured by Oji Scientific Instruments Co., Ltd., trade name: KOBRA-WR), the phase difference (Rth) in the thickness direction of the plastic substrate was measured by changing the elevation angle using light with a wavelength of 589 nm. .

<Heat resistance evaluation>
A plastic substrate was placed in an oven set at 200 ° C., and the appearance was evaluated after heating for 30 minutes.

<Measurement of tensile elongation>
A test piece punched out to 10 mm × 100 mm (SSK 1874-1) was pulled at a speed of 5 mm / min with a Tensilon type tensile tester (Orientec Co., Ltd., trade name: UTM-2.5T), and the maximum point elongation was Asked.

Synthesis Example 1 (Production of diisopropyl fumarate / diethyl fumarate polymer)
Into a 5 liter autoclave was charged 2400 g of distilled water containing 0.2 wt% of hydroxypropylmethylcellulose, 1388 g of diisopropyl fumarate, 212 g of diethyl fumarate, and 12.7 g of perbutyl PV as a polymerization initiator. The polymerization temperature was 45 ° C. and the polymerization time was 36 hours. Suspension radical polymerization reaction was performed under the conditions. The polymer particles obtained were collected by filtration, washed thoroughly with water and methanol, and dried at 80 ° C. to obtain diisopropyl fumarate / diethyl fumarate polymer. The number average molecular weight of the obtained diisopropyl fumarate / diethyl fumarate polymer was 120,000, 87 mol% of diisopropyl fumarate units, and 13 mol% of diethyl fumarate units.

Synthesis Example 2 (Production of diisopropyl fumarate / di-n-butyl fumarate polymer)
Into a 5 liter autoclave, 2600 g of distilled water containing 0.2 wt% of hydroxypropylmethylcellulose, 1232 g of diisopropyl fumarate, 168 g of di-n-butyl fumarate, 11 g of perbutyl PV as a polymerization initiator, a polymerization temperature of 46 ° C., a polymerization time of 42 Suspension radical polymerization reaction was performed under conditions of time. The resulting polymer particles were collected by filtration, washed thoroughly with water and methanol, and dried at 80 ° C. to obtain diisopropyl fumarate / di-n-butyl fumarate polymer. The number average molecular weight of the obtained polymer was 98000, 90 mol% of diisopropyl fumarate units, and 10 mol% of dibutyl fumarate units.

Synthesis Example 3 (Production of diisopropyl fumarate homopolymer)
A 200 mL ampoule was charged with 28 g of diisopropyl fumarate and 0.2 g of perbutyl PV, and after deaeration and nitrogen substitution were repeated several times, a polymerization reaction was carried out at a polymerization temperature of 50 ° C. for 24 hours. After completion of the polymerization, 120 mL of toluene was added to the ampule to dissolve the contents, and then the contents were poured into excess methanol to precipitate a polymer. Filtration and methanol washing were repeated three times, and the polymer was dried at 80 ° C. The number average molecular weight of the obtained polymer was 146000, and the diisopropyl fumarate unit was 100 mol%.

Example 1
80 g of diisopropyl fumarate / diethyl fumarate polymer obtained in Synthesis Example 1 and 20 g of ethyl acrylate polymer (manufactured by Aldrich, molecular weight 48,000) are dissolved in 400 g of toluene to form a 20 wt% solution, and further antioxidant is prevented. 0.15 g of tris (2,4-di-t-butylphenyl) phosphite and 0.05 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) as agents After the addition, it is cast on a support of a solution casting apparatus by a T-die method, and after drying stepwise at a drying temperature of 80 ° C. and then 120 ° C., a heat-resistant transparent plastic substrate for display having a width of 200 mm and a thickness of 50 μm is obtained It was.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

得られたディスプレイ用プラスチック基板は、全光線透過率が高く透明性に優れる、ヘーズが小さい、厚み方向の位相差（Ｒｔｈ）が小さいなど優れた光学特性を有するものであった。更に２００℃でも変形が認められず非常に優れた耐熱性を有していた。また、引張り伸度も良好でありプラスチック基板としてのハンドリング性にも優れていた。

The obtained display plastic substrate had excellent optical characteristics such as high total light transmittance, excellent transparency, small haze, and small thickness direction retardation (Rth). Furthermore, no deformation was observed even at 200 ° C., and it had excellent heat resistance. Further, the tensile elongation was good and the handling property as a plastic substrate was excellent.

Example 2
90 g of diisopropyl fumarate / di-n-butyl fumarate obtained in Synthesis Example 2 and 10 g of ethyl acrylate polymer (manufactured by Aldrich, molecular weight 48,000) were dissolved in 400 g of toluene to obtain a 20 wt% solution. Furthermore, 0.15 g of tris (2,4-di-t-butylphenyl) phosphite and pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) as antioxidants After adding 0.05 g, it was cast on a support of a solution casting apparatus by the T-die method, dried stepwise at a drying temperature of 80 ° C. and then 120 ° C., and then heat resistant and transparent for a display having a width of 200 mm and a thickness of 47 μm. A plastic substrate was obtained.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

  The obtained display plastic substrate had excellent optical characteristics such as high total light transmittance, excellent transparency, small haze, and small thickness direction retardation (Rth). Furthermore, no deformation was observed even at 200 ° C., and it had excellent heat resistance. Further, the tensile elongation was good and the handling property as a plastic substrate was excellent.

Example 3
75 g of diisopropyl fumarate / diethyl fumarate polymer obtained in Synthesis Example 1 and 25 g of ethyl acrylate polymer (manufactured by Aldrich, molecular weight 48,000) were dissolved in 400 g of toluene to give a 20 wt% solution, and further antioxidant was prevented. 0.15 g of tris (2,4-di-t-butylphenyl) phosphite and 0.05 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) as agents After the addition, it is cast on a support of a solution casting apparatus by the T-die method, and after drying stepwise at a drying temperature of 80 ° C. and then 120 ° C., a heat-resistant transparent plastic substrate for display having a width of 200 mm and a thickness of 45 μm is obtained It was.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

  The obtained display plastic substrate had excellent optical characteristics such as high total light transmittance, excellent transparency, small haze, and small thickness direction retardation (Rth). Furthermore, no deformation was observed even at 200 ° C., and it had excellent heat resistance. Further, the tensile elongation was good and the handling property as a plastic substrate was excellent.

Example 4
85 g of diisopropyl fumarate homopolymer obtained in Synthesis Example 3 and 15 g of ethyl acrylate polymer (manufactured by Aldrich, molecular weight 48,000) are dissolved in 400 g of toluene to obtain a 20 wt% solution, and further, tris as an antioxidant. After adding 0.15 g of (2,4-di-t-butylphenyl) phosphite and 0.05 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) The film was cast on a support of a solution casting apparatus by the T-die method and dried stepwise at a drying temperature of 80 ° C. and then 120 ° C., and a heat-resistant transparent plastic substrate for display having a width of 200 mm and a thickness of 50 μm was obtained.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

  The obtained plastic substrate for display had a high total light transmittance, excellent transparency, and a plastic substrate having a small thickness direction retardation (Rth). Furthermore, no deformation was observed even at 200 ° C., and it had excellent heat resistance. Further, the tensile elongation was good and the handling property as a plastic substrate was excellent.

Example 5
90 g of diisopropyl fumarate / di-n-butyl fumarate obtained in Synthesis Example 2 and 10 g of butyl acrylate polymer (manufactured by Soken Chemical Co., Ltd., molecular weight 150,000) were dissolved in 400 g of toluene to obtain a 20 wt% solution. , 0.15 g of tris (2,4-di-t-butylphenyl) phosphite as an antioxidant and pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) 0 .05 g is added, cast onto a support of a solution casting apparatus by a T-die method, dried stepwise at a drying temperature of 80 ° C. and then 120 ° C., and then heat resistant transparent plastic for display having a width of 200 mm and a thickness of 47 μm. A substrate was obtained.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

  The obtained display plastic substrate had excellent optical characteristics such as high total light transmittance, excellent transparency, small haze, and small thickness direction retardation (Rth). Furthermore, no deformation was observed even at 200 ° C., and it had excellent heat resistance. Further, the tensile elongation was good and the handling property as a plastic substrate was excellent.

Comparative Example 1
100 g of diisopropyl fumarate / diethyl fumarate polymer obtained in Synthesis Example 1 was dissolved in 400 g of toluene to give a 20 wt% solution, and tris (2,4-di-t-butylphenyl) phosphite was used as an antioxidant. After adding 0.15 g and 0.05 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), the solution was flowed to the support of the solution casting apparatus by the T-die method. Then, after drying and drying stepwise at a drying temperature of 80 ° C. and then 120 ° C., a heat-resistant transparent plastic substrate for display having a width of 200 mm and a thickness of 50 μm was obtained.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

  The obtained plastic substrate for display had a high total light transmittance and excellent transparency and heat resistance, but had a large thickness direction retardation (Rth) and a small tensile elongation.

Comparative Example 2
100 g of ethyl acrylate polymer (manufactured by Aldrich, molecular weight 48,000) is dissolved in 400 g of toluene to give a 20 wt% solution, and tris (2,4-di-t-butylphenyl) phosphite 0 as an antioxidant. .15 g and 0.05 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) were added, and then casted on the support of the solution casting apparatus by the T-die method. After drying stepwise at a drying temperature of 80 ° C. and then 120 ° C., a plastic substrate having a width of 200 mm and a thickness of 50 μm was obtained.

  And the total light transmittance of the obtained plastic substrate, haze, the phase difference (Rth) of the substrate thickness direction, heat resistance, and tensile elongation were measured. The results are shown in Table 1.

  The obtained plastic substrate was viscous, and was greatly deformed by heating at 200 ° C. and was inferior in heat resistance.

Claims (6)

The number average molecular weight (Mn) containing the fumaric acid diester polymer (A) containing the fumaric acid diester residue unit represented by the following general formula (1) and the acrylic acid ester residue unit represented by the following general formula (2) is: A heat-resistant transparent plastic substrate for flat panel displays, comprising 1 × 10 ^{4 to} 5 × 10 ⁵ acrylic acid ester polymer (B).

(In formula, R < ₁ >, R < ₂ > shows a C3-C12 branched alkyl group or cyclic alkyl group each independently.)

(In the formula, R ₃ represents an alkyl group having 1 to 12 carbon atoms or a cyclic alkyl group.) A polymer in which the fumaric acid diester polymer (A) contains 60 mol% or more of fumaric acid diester residue units represented by the general formula (1) and 40 mol% or less of residue units copolymerizable with fumaric acid diesters. The heat-resistant transparent plastic substrate for flat panel displays according to claim 1, wherein 3. The flat according to claim 1, wherein the acrylic ester polymer (B) is a polymer containing 60 mol% or more of an acrylic ester residue unit represented by the general formula (2). 4. Heat-resistant transparent plastic substrate for panel displays. The fumaric acid diester polymer (A) is 60 to 99% by weight and the acrylic acid ester polymer (B) is 1 to 40% by weight, according to any one of claims 1 to 3. Heat-resistant transparent plastic substrate for flat panel displays. 5. The flat panel display according to claim 1, wherein the thickness of the substrate is 10 to 200 μm, and the retardation (Rth) in the substrate thickness direction is 0 to −200 nm. Heat resistant transparent plastic substrate. The heat-resistant transparent plastic substrate for a flat panel display according to any one of claims 1 to 5, wherein the haze is 2% or less.