JP2008045093A - Polysulfone resin and optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film having good transparency/heat-resistance and low birefringence. <P>SOLUTION: The optical film comprises a polysulfone resin having a spiro structure expressed by general formula (1) (the ring α is a polycyclic group; two rings α may be the same or different and are bonded through a spiro bond; and the ring α may have substituents.). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polysulfone resin and an optical film excellent in optical properties. The polysulfone resin of the present invention has good transparency and heat resistance, and has low birefringence.

  Inorganic glass materials are widely used as transparent materials because they are excellent in transparency and heat resistance and have small optical anisotropy. However, since inorganic glass has a large specific gravity and is brittle, a molded glass product is heavy and has a defect such as being easily damaged. Due to such drawbacks, in recent years, development of plastic materials that replace inorganic glass materials has been actively conducted.

  As plastic materials for the purpose of replacing such inorganic glass materials, for example, polymethyl methacrylate, polycarbonate, polyethylene terephthalate and the like are known. Since these plastic materials are lightweight, excellent in mechanical properties, and excellent in processability, these plastic materials are recently used in various applications such as lenses and films.

  On the other hand, in the field of flat panel displays such as liquid crystal display elements, there is an increasing need for improvement in breakage resistance, weight reduction, and thickness reduction, and replacement of glass substrates with plastic film substrates is being studied. Since a plastic film substrate can be a flexible substrate, it can be used as a substrate for a mobile information communication device display device such as a portable information terminal such as a mobile phone, an electronic notebook, or a laptop personal computer. As a substrate of a display device, a functional material such as a transparent conductive film or a switching element is formed on a film. At that time, processing at a high temperature is required to improve the performance of the formed functional material, and at least 240 ° C. It is desired to provide a plastic substrate having the above heat resistance.

  As heat-resistant plastics used for the above purpose, heat-resistant amorphous polymers such as modified polycarbonate (modified PC), polyethersulfone (PES), and cycloolefin copolymer have been known so far. However, there is a problem that sufficient heat resistance as a plastic film substrate cannot be obtained even if these heat-resistant plastics are used.

  Furthermore, conventional plastics generate birefringence due to molecular orientation when formed into a film shape from the film forming conditions and the optical elasticity coefficient peculiar to the resin. There was a problem that the display quality was remarkably lowered and the optical properties were inferior to those of glass. For this reason, the plastic film substrate is required to have both higher optical isotropy and heat resistance.

Low birefringence polysulfone resins using substituted bisphenol have been developed as a technique for solving the above-mentioned problems in the optical properties of plastics (see, for example, Patent Document 1). However, this polysulfone resin has insufficient heat resistance and has a problem in practical use when used as an optical film. Therefore, it has been strongly desired to develop a plastic material that solves the problems of the plastic materials that have been proposed so far, has high heat resistance, and sufficiently satisfies mechanical characteristics and optical characteristics.
JP-A-11-217438

  The present invention has been made to solve the problems of conventional plastic materials, and a first object of the present invention is to provide a resin having excellent heat resistance, optical properties and mechanical properties. . The second object of the present invention is the resin composition suitable for a transparent conductive film substrate, a TFT substrate, a liquid crystal display substrate, an organic EL display substrate, an electronic paper substrate, a solar cell substrate, an optical disk substrate, a touch panel, and the like. An object of the present invention is to provide an optical film using an object.

  As a result of diligent investigations regarding the solution of the above-described problems, the present inventors have included a specific chemical structure having a spiro structure or a cardo structure in which a plurality of rings are orthogonal or intersecting with each other in the main chain of the polymer. It has been found that the above resin composition can solve these problems and can provide an optical film excellent in heat resistance, optical characteristics and the like, and has completed the present invention.

That is, the said subject of this invention is achieved by the following means.
[1] A polysulfone resin having a spiro structure represented by the following general formula (1).

（式中、環αは多環式の環を表し、２つの環αはそれぞれ同じであっても異なっていてもよく、２つの環はスピロ結合によって結合されている。なお、環αは置換基を有していてもよい。）

(In the formula, ring α represents a polycyclic ring, the two rings α may be the same or different, and the two rings are connected by a spiro bond. It may have a group.)

[2] The polysulfone resin according to [1], wherein among the rings constituting the ring α, a ring forming a spiro bond is a 5- or 6-membered ring.

[3] The ring that forms the spiro bond among the rings constituting the ring α forms a condensed ring with the ring that forms the spiro bond, and is a benzene ring or a naphthalene ring. The polysulfone resin according to [1] or [2].

[4] The polysulfone resin according to any one of [1] to [3], wherein the sulfone moiety is represented by the following general formula (2).

（式中、Ｒ¹¹およびＲ¹²は、それぞれ独立に置換基を表す。また、Ｒ¹¹およびＲ¹²は、それぞれが連結して環を形成してもよい。ｐ１およびｐ２は、それぞれ０〜４の整数を表す。）

(In the formula, R ¹¹ and R ¹² each independently represent a substituent. R ¹¹ and R ¹² may be linked to each other to form a ring. P1 and p2 are each 0-4. Represents an integer.)

[5] An optical film comprising the polysulfone resin according to any one of [1] to [4].

[6] An optical film comprising a polysulfone resin having a cardo structure represented by the following general formula (3).

（式中、環βは芳香族環を含む多環式の環を表し、環γは単環式または多環式の環を表し、２つの環γはそれぞれ同じであっても異なっていてもよく、環β上の１つの４級炭素に連結されている。なお、環βおよび環γは、それぞれ置換基を有していてもよい。）

(Wherein ring β represents a polycyclic ring containing an aromatic ring, ring γ represents a monocyclic or polycyclic ring, and two rings γ may be the same or different, respectively. It is often linked to one quaternary carbon on ring β, where ring β and ring γ may each have a substituent.)

[7] The optical film as described in [6], wherein the ring β is a polycyclic ring.

[8] The optical film as described in [6] or [7], wherein the ring γ is a monocyclic ring.

[9] The optical film according to any one of [6] to [8], wherein the sulfone moiety of the sulfone resin is represented by the general formula (2).

  If the polysulfone resin of the present invention is used, an excellent optical film having good transparency and heat resistance and low birefringence can be provided.

  Hereinafter, the resin and the optical film of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Polysulfone resin]
The polysulfone resin of the present invention has at least one unit represented by the following general formula (1).

  In general formula (1), ring α represents a polycyclic ring, and two rings α may be the same or different from each other, and the two rings are connected by a spiro bond. Ring α may have a substituent.

  In order to improve heat resistance, among the rings constituting the ring α, the ring that is bonded to the ring that forms the spiro bond is an aromatic ring, and the ring that forms the spiro bond forms a condensed ring. The aromatic ring is more preferably a benzene ring or a naphthalene ring. The rings α are preferably the same in terms of synthesis.

  In order to make birefringence lower, the ring forming the spiro bond is preferably a 5-membered ring or a 6-membered ring, and a 5-membered ring is particularly preferable. Examples of the 5-membered ring include a cyclopentane ring, an oxolane ring, a dioxolane ring, a thioxolane ring and an azolidine ring, and a cyclopentane ring and an oxolane ring are preferable. Examples of the 6-membered ring include a cyclohexane ring, an oxane ring, a dioxane ring, a thioxan ring, and a piperidine ring, and a cyclohexane ring and an oxane ring are preferable.

  The substituent is not particularly limited and can be appropriately selected within a range that does not hinder the effects of the present invention. For example, a halogen atom, an alkyl group (C1-C10 is preferable, and 1-5 are more preferable. For example, a methyl group, an ethyl group, n-propyl group, i-propyl group, tert-butyl group, trifluoromethyl group, etc. ), An aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20). For example, phenyl group, 2-methylphenyl group, 2,4-dimethylphenyl group, 2-chlorophenyl group, 4-methoxyphenyl group, penta Fluorophenyl group, 1-naphthyl group, 2-naphthyl group, etc.). Particularly preferred substituents are a chlorine atom, a methyl group, and a phenyl group.

  As a preferable example of the polysulfone resin having a spiro structure represented by the general formula (1), a polysulfone resin having a spirobiindane structure represented by the following general formula (1A) in a repeating unit, represented by the following general formula (1B) A polysulfone resin containing a spirobichroman structure in the repeating unit, a polysulfone resin containing a spirobibenzofuran structure represented by the following general formula (1C) in the repeating unit, and a spirobifluorene represented by the following general formula (1D) And a polysulfone resin containing a structure represented by the formula in the repeating unit. Among these, in terms of optical properties, a polysulfone resin containing a structure represented by the following general formula (1A) or the following general formula (1D) in the repeating unit is more preferable, and a structure represented by the following general formula (1A) is preferable. Polysulfone resin contained in the repeating unit is particularly preferable.

In general formula (1A), R ³¹ and R ³² each independently represent a hydrogen atom or a substituent. R ³³ represents a substituent. R ³¹ , R ³² and R ³³ may be linked to each other to form a ring. R ³¹ and R ³² may be connected to each other to form a ring. m and n each independently represents an integer of 0 to 3, preferably 0 to 2. Examples of the substituent are a halogen atom, an alkyl group, and an aryl group. More preferred examples of R ³¹ and R ³² are a hydrogen atom, a methyl group, and a phenyl group, and more preferred examples of R ³³ are a chlorine atom, a bromine atom, a methyl group, an isopropyl group, a tert-butyl group, and a phenyl group. is there. Z represents a single bond or a linking group that can form the main chain structure of the polysulfone resin. The linking group is preferably a ketone, ether, sulfide, sulfoxide, or sulfone, more preferably ether or sulfone, and particularly preferably ether.

In the general formula (1B), R ⁴¹ represents a hydrogen atom or a substituent. R ⁴² represents a substituent. R ⁴¹ and R ⁴² may be connected to each other to form a ring. m and n each independently represents an integer of 0 to 3, preferably 0 to 2. Examples of the substituent include a halogen atom, an alkyl group, and an aryl group. More preferred examples of R ⁴¹ are hydrogen atom, methyl group or phenyl group, and more preferred examples of R ⁴² are chlorine atom, bromine atom, methyl group, isopropyl group, tert-butyl group or phenyl group. Z is the same as in the general formula (1A).

In the general formula (1C), R ⁵¹ represents a hydrogen atom or a substituent. R ⁵² represents a substituent. R ⁵¹ and R ⁵² may be connected to each other to form a ring. m and n each independently represents an integer of 0 to 3, preferably 0 to 2. Z is the same as in the general formula (1A). Examples of the substituent include a halogen atom, an alkyl group, and an aryl group. More preferred examples of R ⁵¹ are hydrogen atom, methyl group or phenyl group, and more preferred examples of R ⁵² are chlorine atom, bromine atom, methyl group, isopropyl group, tert-butyl group or phenyl group.

In the general formula (1D), R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ each independently represent a substituent. R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ may be linked to each other to form a ring. j, k, l and p each independently represents an integer of 0 to 4, preferably 0 to 2. X represents a single bond or a divalent linking group, and two Xs may be the same or different. The number of elements constituting the divalent linking group is preferably 1 to 6, more preferably 1 to 3, and examples thereof include —O—, —S—, —CO—, —NH—, and —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, cyclopentylidene, cyclohexylidene and combinations thereof, and the like, preferably —O—, —CO—, —C (CH ₃ ) ₂ —, — C (CF ₃ ) ₂ —, more preferably —O—, —C (CH ₃ ) ₂ —, and —C (CF ₃ ) ₂ —. Examples of the substituent are a halogen atom, an alkyl group or an aryl group, and more preferable examples are a chlorine atom, a fluorine atom, a bromine atom, a methyl group, an isopropyl group, a tert-butyl group or a phenyl group. Z is the same as in the general formula (1A).

  Specific examples of the structure represented by the general formula (1) are given below, but the structure of the general formula (1) that can be employed in the present invention is not limited thereto. In addition, the structure (Z) of the polymerization site | part for comprising a polymer is abbreviate | omitted.

  As the polysulfone resin of the present invention, those having a sulfone moiety represented by the following structural formula can be preferably used.

General formula (2), R < ¹¹ > and R < ¹² > represent a substituent each independently. R ¹¹ and R ¹² may be connected to each other to form a ring. p1 and p2 each independently represents an integer of 0 to 4, preferably 0 to 2.
Examples of the substituent include a halogen atom and an alkyl group (preferably having 1 to 10 carbon atoms, more preferably 1 to 5. For example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a tert-butyl group, Trifluoromethyl group and the like) and aryl groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20. For example, phenyl group, 2-methylphenyl group, 2,4-dimethylphenyl group, 2-chlorophenyl group, 4- Methoxyphenyl group, pentafluorophenyl group, 1-naphthyl group, 2-naphthyl group, etc.), preferably chlorine atom, fluorine atom, bromine atom, methyl group, isopropyl group, tert-butyl group or phenyl group is there.

  Specific examples of the structure represented by the general formula (2) are given below, but the structure of the general formula (2) that can be employed in the present invention is not limited to these.

  Moreover, polysulfone resin which has a cardo structure of General formula (3) is mentioned as resin used suitably for the optical film of this invention. As a preferred example of the resin having a cardo structure represented by the general formula (3), a polysulfone resin having a repeating unit represented by a structure represented by the following general formula (3A) in the repeating unit, the following general formula (3B) The polysulfone resin which contains in the repeating unit the structure represented by spirobifluorene can be mentioned.

  In general formula (3), ring β represents a polycyclic ring including an aromatic ring, ring γ represents a monocyclic or polycyclic ring, and two rings γ are the same or different. And is linked to one quaternary carbon on ring β. Two rings γ may be linked to each other. Of the rings constituting ring β, the ring that is bonded to the ring that forms a bond with ring γ is an aromatic ring, and the ring that forms the bond with ring γ forms a condensed ring. Preferably, the aromatic ring is a benzene ring or a naphthalene ring. Ring γ is preferably a monocyclic ring. The ring γ is preferably aromatic. Specifically, a benzene ring can be mentioned as a suitable example. The rings γ are preferably the same in the synthesis.

  Ring β and ring γ may each have a substituent. The substituent is not particularly limited and can be appropriately selected within a range that does not hinder the effects of the present invention. For example, a halogen atom, an alkyl group (C1-C10 is preferable, and 1-5 are more preferable. For example, a methyl group, an ethyl group, n-propyl group, i-propyl group, tert-butyl group, trifluoromethyl group, etc. ), An aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20). For example, phenyl group, 2-methylphenyl group, 2,4-dimethylphenyl group, 2-chlorophenyl group, 4-methoxyphenyl group, penta Fluorophenyl group, 1-naphthyl group, 2-naphthyl group, etc.). Particularly preferred substituents are a chlorine atom, a methyl group, and a phenyl group.

In general formula (3A), R ⁶⁵ , R ⁶⁶ , R ⁶⁷ and R ⁶⁸ each independently represent a substituent. X is the same as in the general formula (1D). j, k, l and p each independently represents an integer of 0 to 4, preferably 0 to 2. Z is the same as in the general formula (1A).

In general formula (3B), R ⁶¹ , R ⁶² , R ⁶³ , R ⁶⁴ , X, j, k, l and p are the same as in general formula (1D). Z is the same as in the general formula (1A).

  Specific examples of the structure represented by the general formula (3) are given below, but the structure of the general formula (3) that can be employed in the present invention is not limited to these. In addition, the structure (Z) of the polymerization site | part for comprising a polymer is abbreviate | omitted.

As the polysulfone resin having a structure represented by the general formula (3) according to the present invention, those having a sulfone moiety represented by the general formula (2) can be preferably used. In addition, General formula (3) and General formula (2) are couple | bonded directly or through the coupling group. As the linking group, ketone, ether, sulfide, sulfoxide, and sulfone are preferable, ether or sulfone is more preferable, and ether is particularly preferable.
Each of the structures represented by the general formula (1), the general formula (2), and the general formula (3) included in the polysulfone resin of the present invention may be one kind or plural kinds.

  Specific examples of the polysulfone resin suitable for the optical film of the present invention are given below, but the polysulfone resin that can be used in the present invention is not limited thereto.

  The molecular weight of the polysulfone resin is 10,000 or more in terms of weight average molecular weight, more preferably 20,000 to 300,000, and particularly preferably 30,000 to 200,000. When the molecular weight is 10,000 or more, film forming becomes easy, and preferable mechanical properties are easily obtained after forming. Further, if the molecular weight is 300,000 or less, the molecular weight can be easily controlled in the synthesis, and the viscosity of the solution is too high so that the handling is not difficult. The viscosity corresponding to the molecular weight can be used as a guide.

  The heat resistant temperature of the polysulfone resin is preferably higher, and the glass transition temperature (Tg) measured by DSC can be used as a guide. In this case, the preferable glass transition temperature is 200 ° C. or higher, more preferably 220 ° C. or higher, and particularly preferably 240 ° C. or higher. Further, the case where the glass transition temperature is not substantially observed within the measurement range (for example, 400 ° C. or lower) is also included in the polysulfone resin of the present invention. In general, increasing the heat resistant temperature can be achieved by increasing the number of aromatic rings or increasing the number of condensed rings. In the polysulfone resin of the present invention, it is preferable to increase the number of aromatic rings contained in the polymer main chain, not as a substituent.

  The production method of the polysulfone resin is not particularly limited, and a known method such as a nucleophilic substitution polycondensation method can be applied. Specifically, (1) a method in which an alkali metal salt of a diol and a dihalide having a sulfonyl group are heated in a polar solvent for polycondensation, or (2) a diol in a polar solvent in the presence of an alkali metal or metal salt. And a method of polycondensing by heating a dihalide having a sulfonyl group.

  Examples of polar solvents used in these polycondensation reactions include dimethyl sulfoxide, sulfolane, diphenyl sulfone, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl- An amide solvent such as 2-imidazolidinone is used. These may be used alone or in combination of two or more. In each method, an azeotropic dehydration solvent such as toluene, benzene, chlorobenzene, monochloroethane, dichloroethane, trichloroethane, tetrachloroethane, dichlorobenzene or the like may be added as necessary.

  Further, a preferred specific example of the alkali metal salt used in the method (1) is a sodium salt or a potassium salt. The alkali metal salt used in the method (2) is not particularly limited. For example, sodium carbonate, potassium carbonate, rubidium carbonate, sodium oxalate, potassium oxalate and the like are preferable, and sodium carbonate and potassium carbonate are particularly preferable. . The amount used is preferably an excess mole relative to the molar amount of diphenol in order to obtain a high molecular weight polymer. When producing a polysulfone by the above method (1) or (2), the polymerization temperature is usually in the range of 100 to 400 ° C, more preferably 150 to 280 ° C.

  The reaction is preferably free of oxygen in the reaction atmosphere, and is desirably performed in nitrogen or another inert gas. When the polysulfone is produced by the above method (1) or (2), the reaction mixture is usually cooled to stop the polymerization reaction. Furthermore, in order to stabilize the phenoxide group that may be present at the end of the polymer and stop the polymerization reaction, an aliphatic halide, an aromatic halide, etc. are added and reacted in the latter stage of the reaction. This is also carried out as necessary.

  When a polysulfone resin is produced by the method (1) or (2), a known method can be applied as a method for separating and purifying the produced polymer. For example, after the salt (and excess alkali metal salt) precipitated in the reaction solvent is filtered, the polymer solution which is the filtrate is usually dropped into the poor solvent of the polymer, or conversely, the poor polymer solvent is added to the polymer solution. By adding in, the target polymer can be precipitated. Typical examples of the poor solvent for the polymer include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, water, and the like. These may be used alone or as a mixture of two or more. . Further, the salt may be removed by washing with water after the polymer is precipitated by the above method without separating the precipitate.

  The amount of residual alkali metal and halogen in the polysulfone resin is preferably 50 ppm or less, particularly preferably 10 ppm or less. If the amount of residual alkali metal and the amount of halogen are 50 ppm or less, the electrical characteristics are unlikely to deteriorate and it is easy to obtain excellent film surface characteristics. In addition, an excellent functional film can be provided even when a conductive film, a semiconductor film, or the like is provided. The amount of residual alkali metal and the amount of halogen can be quantified using known methods such as ion chromatography analysis, atomic absorption spectrometry, and plasma emission spectroscopy.

  The amount of monomer remaining in the polysulfone resin is preferably 3000 ppm or less, more preferably 500 ppm or less, and even more preferably 100 ppm or less. If the residual monomer amount is 3000 ppm or less, the electrical characteristics are unlikely to deteriorate, and excellent film surface characteristics can be easily obtained. Also, an excellent functional film can be provided when a barrier film, a conductive film, a semiconductor film, or the like is provided. The amount of residual monomer can be analyzed by a known method such as HPLC or nuclear magnetic resonance.

[Optical film]
The optical film of the present invention contains the polysulfone resin of the present invention having at least one unit represented by the general formula (1). The optical film of the present invention includes those having a shape generally regarded as a sheet. As a method for forming the polysulfone resin of the present invention into a film or sheet, known methods such as a melt film forming method and a solution casting method can be used.

  The melt casting method has features such as low film production costs and excellent optical isotropy of the film. However, a polymer with a high glass transition temperature (as a guideline, 250 ° C or higher) requires a high melting temperature. There is a problem that the polymer is likely to be thermally decomposed. The solution casting method is suitable for forming a polymer with a high glass transition temperature or a polymer with a high molecular weight and a high melt viscosity, and has excellent film surface properties, but it uses a solvent and has a large environmental impact. There is a problem.

  The optical film of the present invention may be stretched. By stretching, mechanical strength such as folding strength is improved, and there is an advantage that handling property is improved. In particular, those having an orientation release stress in the stretching direction (ASTMD 1504, hereinafter abbreviated as “ORS”) of 0.3 to 3 GPa are preferable because the mechanical strength is improved. ORS is an internal stress generated by stretching inherent in a stretched optical film. For the stretching, a known method can be used. However, when the glass transition temperature of the polysulfone resin is 250 ° C. or higher, the stretching may be difficult only by simple heating. Therefore, it is desirable to perform the stretching in a state containing a solvent. . In this case, it is preferable to perform stretching in the course of drying, for example, a roll uniaxial stretching method or a tenter uniaxial stretching at a temperature between 10 ° C. and 50 ° C. higher than the glass transition temperature in a state containing a solvent. The film can be stretched by a method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, or an inflation method. The draw ratio is preferably 1.1 to 3.5 times, and more preferably 1.2 to 2.5 times.

  The polysulfone resin that forms the optical film of the present invention may be one kind or a mixture of two or more kinds. Moreover, polymers and additives other than polysulfone resin may be included within the range not impairing the effects of the present invention. The amount of components other than the polysulfone resin contained in the optical film of the present invention is preferably 0 to 40% by mass, more preferably 0 to 20% by mass, and further preferably 0 to 10% with respect to the mass of the polysulfone resin. % By mass. Furthermore, a crosslinked resin may be added from the viewpoint of solvent resistance, heat resistance, mechanical strength, and the like. As the kind of the cross-linked resin, various known ones can be used without any particular limitation as the thermosetting resin and the radiation curable resin.

  Examples of the thermosetting resin include phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, silicone resin, diallyl phthalate resin, furan resin, bismaleimide resin, cyanate resin and the like. In addition, the crosslinking method can be used without particular limitation as long as it is a reaction that forms a covalent bond, and there is a system in which the reaction proceeds at room temperature using a polyalcohol compound and a polyisocyanate compound to form a urethane bond. Can be used without any particular restrictions. However, such a system often has a problem of pot life before film formation, and is usually used as a two-component mixed type in which a polyisocyanate compound is added immediately before film formation.

  On the other hand, when used as a one-component type, it is effective to protect the functional group involved in the crosslinking reaction, and it is also commercially available as a block type curing agent. As commercially available block type curing agents, B-882N manufactured by Mitsui Takeda Chemical Co., Ltd., Coronate 2513 manufactured by Nippon Polyurethane Industry Co., Ltd. (above block polyisocyanate), Cymel 303 manufactured by Mitsui Cytec Co., Ltd. (methylated melamine resin) ) Etc. are known.

  Radiation curable resins are roughly classified into radical curable resins and cationic curable resins. As the curable component of the radical curable resin, a compound having a plurality of radical polymerizable groups in the molecule is used. As a typical example, a polyfunctional acrylate monomer having 2 to 6 acrylate groups in the molecule And compounds having a plurality of acrylate groups in the molecule called urethane acrylate, polyester acrylate, and epoxy acrylate. As a typical curing method of the radical curable resin, there are a method of irradiating an electron beam and a method of irradiating ultraviolet rays. Usually, in the method of irradiating with ultraviolet rays, a polymerization initiator that generates radicals upon irradiation with ultraviolet rays is added. In addition, if the polymerization initiator which generate | occur | produces a radical by heating is added, it can also be used as a thermosetting resin. As the curable component of the cationic curable resin, a compound having a plurality of cationic polymerizable groups in the molecule is used. As a typical curing method, a photoacid generator that generates an acid upon irradiation with ultraviolet rays is added, and ultraviolet rays are added. And a method of curing by irradiation. Examples of the cationically polymerizable compound include a compound containing a ring-opening polymerizable group such as an epoxy group and a compound containing a vinyl ether group.

  In the optical film of the present invention, a plurality of the thermosetting resins and radiation curable resins mentioned above may be mixed and used, or a thermosetting resin and a radiation curable resin may be used in combination. Moreover, you may mix and use a crosslinkable resin and the polymer which does not have a crosslinkable group.

  Furthermore, the optical film of the present invention can also introduce a crosslinkable group into the polysulfone resin of the present invention used at the time of film formation, and is crosslinkable at any site in the polymer main chain end, polymer side chain, or polymer main chain. It may have a group. In this case, it can bridge | crosslink without using the general purpose crosslinkable resin mentioned above together.

  The optical film of the present invention can contain a metal oxide and / or a metal complex oxide and a metal oxide obtained by a sol-gel reaction. In this case, heat resistance and solvent resistance can be imparted in the same manner as the above-mentioned crosslinked resins. Furthermore, resin modifiers such as plasticizers, dyes / pigments, antistatic agents, ultraviolet absorbers, antioxidants, inorganic fine particles, peeling accelerators, leveling agents, and lubricants as long as the effects of the present invention are not impaired as necessary. May be added.

  The thickness of the optical film of the present invention is not particularly defined, but is preferably 30 to 700 μm, more preferably 40 to 200 μm, and further preferably 50 to 150 μm. In any case, the haze is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. Further, the total light transmittance is preferably 70% or more, more preferably 80% or more, and further preferably 85% or more.

  The heat resistant temperature of the optical film of the present invention is preferably higher, and the glass transition temperature by DSC measurement can be used as a guide. In this case, a preferable glass transition temperature is 200 ° C. or higher, more preferably 220 ° C. or higher, and further preferably 240 ° C. or higher. In addition, when the optical film of the present invention is produced by the solution casting method using only the polysulfone resin of the present invention, the glass transition temperature of the polysulfone resin used and the glass transition of the optical film of the present invention are sufficient if drying is sufficient. It almost coincides with temperature.

The surface of the optical film of the present invention is treated by a method such as saponification, corona treatment, flame treatment, glow discharge treatment, etc., in order to enhance the adhesion with other layers or components depending on the application. Can do. Furthermore, an adhesive layer and an anchor layer may be provided on at least one side of the optical film.
Moreover, various well-known functional layers, such as a smoothing layer, a hard-coat layer, an ultraviolet absorption layer, a surface roughening layer, a transparent conductive layer, and a gas barrier layer, can be provided on the surface of the optical film.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples are appropriately changed without departing from the gist of the present invention. be able to. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

1. Synthesis of polysulfone resin [polysulfone resin P-1]
113 ml of dimethylacetamide, 13.0 g of potassium carbonate, 19.2 g of spirobibenzofurandol, and 21.5 g of 4-chlorophenylsulfone were put into a reaction vessel equipped with a stirrer and stirred at 160 ° C. under a nitrogen stream at 100 rpm. For 20 hours. 150 ml of dimethylacetamide was added to the reaction solution and filtered to remove inorganic salts. The resulting solution was poured into 5 liters of vigorously stirred methanol. The white precipitate obtained in methanol was collected by filtration, dried by heating at 40 ° C. for 12 hours, and then dried at 70 ° C. for 3 hours under reduced pressure to obtain 31 g of a white powder.
When the obtained white powder was confirmed by H ¹ -NMR spectrum, the proton peak at the ortho position of Cl observed at δ 7.46 ppm of 4-chlorophenylsulfone used as a raw material disappeared, and was expressed at δ 6.88 ppm. It confirmed that it superposed | polymerized by. Further, as a result of measuring the molecular weight by GPC (HLC-8120 manufactured by Tosoh Corporation; chloroform solvent; compared with a molecular weight standard product of polystyrene), the weight average molecular weight was 80,000, so that the polysulfone resin P- of the present invention was used. 1 was identified. Moreover, the glass transition temperature measured by DSC (DSC6200 by Seiko Co., Ltd .; in nitrogen; temperature rising temperature 10 degree-C / min) was 240 degreeC.

[Polysulfone resin P-2]
Except for changing spirobibenzofurandiol to tetramethylspirobiindanediol having the same molar amount, the same synthesis method as that of polysulfone resin P-1 was employed to obtain polysulfone resin P-2 having a weight average molecular weight of 87,000. It was.

[Polysulfone resin P-6]
Except for changing the spirobibenzofurandol to the same molar amount of spirobichromandiol, the same synthesis method as that for the polysulfone resin P-1 was employed to obtain a polysulfone resin P-6 having a weight average molecular weight of 56,000.

[Polysulfone resin P-10]
Except for changing the spirobibenzofurandol to the same molar amount of fluorene bisphenol, the same synthesis method as that of the polysulfone resin P-1 was employed to obtain a polysulfone resin P-10 having a weight average molecular weight of 78,000.

2. Production of optical film sample [Production by solution casting method]
Polysulfone resins P-1, P-2, P-6, and P-10 of the present invention, and polycarbonate (chroman PC) derived from spirobichromandiol, which is a comparative resin, are derived from tetramethylspirobiindanediol. Polycarbonate (Indan PC) is dissolved in chloroform, and polyether sulfone (PES; Sumitrite FS-1300, manufactured by Sumitomo Bakelite Co., Ltd.) is dissolved in dichloromethane / trichloroethane = 1/1 (mass ratio). The solution viscosity after dissolution was adjusted to a concentration within the range of 200 to 1500 mPa · s. Each of the obtained solutions was filtered through a 5 μm filter and then cast on a glass substrate using a doctor blade. After casting, it was dried by heating at 50 ° C. for 2 hours, 80 ° C. for 2 hours, 120 ° C. for 4 hours, and dichloromethane / trichloroethane solvent at 150 ° C. for 4 hours. The formed film was peeled from the glass substrate to obtain optical film samples 101 to 103, 105, and 107 to 109.

[Production by hot press method]
Using the polysulfone resin P-1 of the present invention and polyethersulfone (PES) which is a comparative resin, films were formed by a hot press method which is a kind of melt film-forming method. Each powdered resin is sandwiched between Upilex S film (75 μm), preheated at 300 ° C. and 0.5 Mpa for 1 minute, pressed at 300 ° C. and 10 Mpa for 3 minutes, 300 ° C. and 20 MPa for 3 minutes, and then the pressure is released. After rapidly cooling to room temperature, the film was peeled from the Upilex S film to obtain optical film samples 104 and 106.

3. Measuring method of characteristic value The film thickness, total light transmittance, Re, and Rth of each of the obtained optical film samples 101 to 109 were measured by the following measuring methods.

[Film thickness]
Measurement was performed with a dial thickness gauge using K402B manufactured by Anritsu Corporation.

[Total light transmittance of film]
It measured with the JASCO-made haze meter.

[Film retardation]
(1) In-plane retardation (Re)
A value at a wavelength of 632.8 nm was measured from a direction perpendicular to the film plane with a phase difference measuring device (manufactured by Oji Scientific Instruments, KOBRA-WR). Re was calculated based on the measurement result and the following formula.
Re = | nMD-nTD | × 100 / d
(In the above formula, nMD represents the refractive index in the film longitudinal direction, nTD represents the refractive index in the film width direction, and d represents the thickness of the film.)
(2) Retardation in the film thickness direction (Rth)
The angle was changed from the oblique direction of the film plane, and the value at a wavelength of 632.8 nm was measured with a phase difference measuring device (manufactured by Oji Scientific Instruments, KOBRA-WR). Rth was calculated based on the measurement result and the following formula.
Rth = {(nMD + nTD) / 2−nTH} × 100 / d
(In the above formula, nMD represents the refractive index in the film longitudinal direction, nTD represents the refractive index in the film width direction, nTH represents the refractive index in the film thickness direction, and d represents the film thickness.)

4). Table 1 shows the measurement results of the characteristic values and the results of measuring the characteristic values by the above measurement method for each of the evaluation samples 101 to 109 together with the weight average molecular weight and the glass transition temperature of the resin used.

  From Table 1, it can be seen that the optical film of the present invention has a high glass transition temperature of the resin used and is excellent in heat resistance, and is excellent in optical characteristics from the results of total light transmittance and retardation. In particular, in terms of optical properties, an excellent film can be provided even when produced by disadvantageous solution casting. In addition, the optical film samples 105 to 109 of the present invention are all confirmed to have a tensile strength (JIS K7127) larger than 50 MPa, and have sufficient mechanical properties.

  From the said Example, it became clear that the polysulfone resin of this invention and the optical film of this invention are excellent in heat resistance, transparency, and a mechanical characteristic.

  If the polysulfone resin of the present invention is used, an excellent optical film having good transparency and heat resistance and low birefringence can be provided. Therefore, the optical film provided by the present invention is suitable for a transparent conductive film substrate, a TFT substrate, a liquid crystal display substrate, an organic EL display substrate, an electronic paper substrate, a solar cell substrate, an optical disk substrate, a touch panel, and the like. Used. Therefore, the present invention has high industrial applicability.

Claims (9)

A polysulfone resin having a spiro structure represented by the following general formula (1):

(In the formula, ring α represents a polycyclic ring, the two rings α may be the same or different, and the two rings are connected by a spiro bond. It may have a group.)   2. The polysulfone resin according to claim 1, wherein among the rings constituting the ring α, a ring forming a spiro bond is a 5- or 6-membered ring.   The ring that forms a spiro bond among the rings constituting the ring α forms a condensed ring with a ring that forms a spiro bond, and is a benzene ring or a naphthalene ring. Item 3. The polysulfone resin according to Item 1 or 2. The polysulfone resin according to any one of claims 1 to 3, wherein the sulfone moiety is represented by the following general formula (2).

(In the formula, R ¹¹ and R ¹² each independently represent a substituent. R ¹¹ and R ¹² may be linked to each other to form a ring. P1 and p2 are each 0-4. Represents an integer.)   An optical film comprising the polysulfone resin according to any one of claims 1 to 4. An optical film comprising a polysulfone resin having a cardo structure represented by the following general formula (3).

(Wherein ring β represents a polycyclic ring containing an aromatic ring, ring γ represents a monocyclic or polycyclic ring, and two rings γ may be the same or different, respectively. It is often linked to one quaternary carbon on ring β, where ring β and ring γ may each have a substituent.)   The optical film according to claim 6, wherein the ring β is a polycyclic ring.   The optical film according to claim 6, wherein the ring γ is a monocyclic ring. The optical film according to claim 6, wherein a sulfone moiety of the sulfone resin is represented by the following general formula (2).

(In the formula, R ¹¹ and R ¹² each independently represent a substituent. R ¹¹ and R ¹² may be linked to each other to form a ring. P1 and p2 are each 0-4. Represents an integer.)