JPWO2005118686A1 - Soluble polyimide and optical compensation member using the same - Google Patents

Abstract

Soluble polyimide with high birefringence and high transparency of the polyimide layer obtained by casting and drying a polyimide solution dissolved in an organic solvent, and a polyimide solution, coating solution, laminated member, and optics using this A compensation member is provided. The in-plane and thickness-direction birefringence of the polyimide layer obtained by casting and drying a polyimide solution dissolved in an organic solvent at 5% or more of the solid component is 0.04 or more and 0.15 Achievable with a soluble polyimide that is:

Description

  The present invention is a polyimide layer obtained by casting and then drying a polyimide solution dissolved in an organic solvent, and a highly soluble polyimide having high birefringence and high transparency, and a polyimide solution, a coating solution using the same, and The present invention relates to a laminated member and an optical compensation member.

In a liquid crystal display device, a retardation plate for the purpose of optical compensation is generally used. As a conventional phase difference plate, but was often used stretched polymeric film, as shown in Patent Document 1, the in-plane maximum refractive index (n _x) and a thickness direction refractive index difference (n _z) the larger, even a thickness retardation value _{R th (= (n x -n} z) d) the film thickness (d) is thin can be expressed, the phase difference film is proposed to be thinner Yes.

  For example, Patent Document 2 discloses a polyimide resin that is appropriately dissolved in methyl ethyl ketone (MEK) on a support such as PMMA (polymethyl methacrylate) for coating polyimide. However, in practice, the birefringence was as small as less than 0.04.

  Patent Document 3 mentions a polyimide resin having a birefringence of 0.001 to 0.2, but the polyimide resin having a birefringence of 0.04 or more is colored or dissolves. However, it is not suitable as a soluble polyimide that can be coated on a support such as PMMA.

Thus, polyimide resin having high solubility in an organic solvent and capable of imparting high birefringence and low colorability to a polyimide layer obtained by casting a polyimide solution to a polymer support and drying is observed. It was not put out.
JP2003-344856 Special table 2000-511296 Special table hei 8-511812

  Soluble polyimide with high birefringence and high transparency of the polyimide layer obtained by solving the above problems and casting and then drying the polyimide solution dissolved in an organic solvent, and a polyimide solution and coating using the same An object is to provide a liquid, a laminated member, and an optical compensation member.

  Accordingly, as a result of intensive studies, the present inventors have found that the solid component is soluble in an organic solvent by 5% or more, and the polyimide layer obtained by casting and drying the polyimide solution dissolved in the solvent is dried in-plane and thickness. A soluble polyimide having a birefringence in the direction of 0.04 or more and 0.15 or less is provided.

  That is, the present invention can solve the above problems by the following.

  1) Solid component 5% or more soluble in an organic solvent, after casting a polyimide solution dissolved in the solvent, the in-plane and thickness direction birefringence of the polyimide layer obtained by drying is 0.04 or more, Soluble polyimide that is 0.15 or less.

2) When the structures of the following general formula (1) and general formula (2) are contained and the respective contents are expressed as x ₁ and y ₁ , x ₁ : y ₁ = 80: 20 to 45:55 1) The soluble polyimide according to 1).

(R ¹ = H, F, CF ₃ , R ² = H, F, CF ₃ and R ¹ and R ² may be the same or different. Ar is an aromatic group.)
3) When the structures of the following general formula (3) and general formula (4) are contained and the respective contents are expressed as x ₂ and y ₂ , x ₂ : y ₂ = 95: 5 to 60:40 1) The soluble polyimide according to 1).

(R ³ =

R ⁴ = —Cl, —F, —CH ₃ , —C (CH ₃ ) ₃ , —CH (CH ₃ ) ₂ , n = 1 to 4, Ar is an aromatic group. )
4) Containing the structures of the following general formula (5) and general formula (6), and when the respective contents are expressed as x ₃ and y ₃ , x ₃ : y ₃ = 90: 10 to 60:40 1) The soluble polyimide according to 1).

(R ⁵ = hydrogen, halogen element, halogenated alkyl group, aromatic group, R ⁶ = hydrogen, halogen element, halogenated alkyl group, aromatic group, and R ₁ and R ₂ are the same or different. (N1 = 1-3, n2 = 1-3, Ar is an aromatic group)
5) Containing the structures of the following general formula (7) and general formula (8), and when the respective contents are expressed as x ₄ and y ₄ , x ₄ : y ₄ = 80: 20 to 45:55 The soluble polyimide according to 1) or 2), which is characterized in that it exists.

(R ¹ = H, F, CF ₃ , R ² = H, F, CF ₃ and R ₁ and R ₂ may be the same or different.)
6) When the structures of the following general formula (9) and general formula (10) are contained and the respective contents are expressed as x ₅ and y ₅ , x ₅ : y ₅ = 95: 5 to 60:40 The soluble polyimide according to 1) or 3), which is characterized in that it exists.

(R ³ =

^{R 4 = -Cl, -F, -CH} 3, -C (CH 3) 3, -CH (CH 3) is _2, n = _1~4. )
7) When the structures of the following general formula (11) and general formula (12) are contained and the respective contents are expressed as x ₆ and y ₆ , x ₆ : y ₆ = 90: 10 to 60:40 The soluble polyimide according to 1) or 4), which is characterized in that it exists.

(R ⁵ = H, F, CF ₃ , R ⁶ = H, F, CF ₃ and R ⁵ and R ⁶ may be the same or different. N1 = 1 to 3, n2 = 1 to 3 .)
8) A laminated member in which the polyimide solution obtained by dissolving the soluble polyimide according to any one of 1) to 7) is cast on a support and then dried to form a polyimide layer on the support, Or an optical compensation member.

  9) The laminated member or optical compensation member according to 8), wherein the polyimide layer has a thickness of 1 μm or more and less than 40 μm.

  10) A polyimide solution obtained by dissolving the soluble polyimide according to any one of 1) to 7) or a polyimide coating solution.

  The soluble polyimide of the present invention is soluble in an organic solvent at a solid component of 5% or more, and after casting a polyimide solution dissolved in the organic solvent, the polyimide layer obtained by drying has a birefringence of 0.04 or more, 0.15 or less. For example, the retardation film can be thinned by using the soluble polyimide in a retardation application for optical compensation.

Sample cutting Birefringence measurement method

  The gist of the polyimide resin according to the present invention is that the solid component is 5% or more soluble in an organic solvent, and the birefringence of a polyimide layer obtained by casting and drying a polyimide solution dissolved in the solvent is reduced. It is a soluble polyimide that is 0.04 or more and 0.15 or less. The soluble polyimide can also be used as an optical compensation member. For example, TAC (triacetylcellulose) or the like can be coated as a support with soluble polyimide and used as an optical compensation member.

  Here, the organic solvent is an organic solvent in which polyimide is dissolved in a polyimide layer forming step in which a polyimide solution is cast on a support made of a polymer and dried. The organic solvent is not particularly limited as long as it is a solvent that dissolves polyimide. However, in the polyimide layer forming step, a solvent that has little influence on a support made of a polymer (for example, dissolution or swelling that impairs characteristics and uniformity) is used. It is preferable to use it. For example, amide solvents such as NMP (N-methylpyrrolidone) and DMF (N, N-dimethylformamio), ester solvents such as ethyl acetate, halogen solvents such as chloroform and dichloromethane, ethers such as dioxolane and diethyl ether A system solvent, a ketone solvent such as MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), and cyclohexanone, and an aromatic hydrocarbon solvent such as toluene and xylene can be used. In addition, a non-solvent that does not dissolve polyimide or a poor solvent that is difficult to dissolve may be used as a mixed solvent in a timely manner as long as the polyimide is dissolved. Organic solvents in which polyimide is dissolved are halogen solvents such as chloroform and dichloromethane, ether solvents such as dioxolane and diethyl ether, ketone solvents such as MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), and cyclohexanone. In the formation process, it is more preferable in that it has less influence on the support made of a polymer, and the degree of ether solvent such as dioxolane and diethyl ether, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), cyclohexanone, which is more excellent in its degree. More preferred are ketone solvents such as MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), and cyclohexanone.

  On the other hand, various supports can be used, but from the viewpoint of weight reduction, a support made of a polymer, and a support made of an organic polymer used for optical applications, etc. are preferably used. it can. Specific examples of the material constituting the support include PMMA, TAC (or celluloses), PET (polyethylene terephthalate), PC (polycarbonate), and the like. In particular, PMMA, TAC (or celluloses), PET, and TAC (or celluloses) can be preferably used. In addition, it is preferable that a support body is a film form from viewpoints, such as weight reduction.

  The thickness of the polyimide layer formed on the support after being cast on the support is preferably 1 μm or more and less than 40 μm, and more preferably 1 μm or more and less than 20 μm in that the optical compensation member can be thinned. preferable.

  Here, the polyimide layer is preferably a polyimide molded body having a residual solvent amount of less than 1% obtained by casting and drying a polyimide solution dissolved in an organic solvent.

  The birefringence in the in-plane and thickness direction of the polyimide layer is the difference between the in-plane refractive index and the thickness direction refractive index, and is preferably 0.04 or more and 0.15 or less. More preferably, it is 0.05 or more and 0.15 or less. When the birefringence in the in-plane and thickness direction of the polyimide layer is less than 0.04, when used in a retardation film application, it is necessary to increase the thickness of the polyimide layer, and coloring of soluble polyimide is a problem depending on the use application. May be. If the birefringence in the plane and in the thickness direction exceeds 0.15, it may be difficult to control the thickness of the polyimide layer in applications where uniform birefringence characteristics are required. The in-plane birefringence in the thickness direction is not particularly a value when the thickness is specified, but is preferably achieved with a thickness of 1 μm or more and less than 40 μm, more preferably 1 μm or more and less than 30 μm. Further, it is preferably achieved at 5 μm or more and less than 25 μm, particularly 20 μm.

  Although the acid dianhydride that can be suitably used for the soluble polyimide of the present invention may partially depend on the structure of the diamine, the synthesized polyimide can be provided with solubility in an organic solvent, and the polyimide layer can be added to the polyimide layer. Those capable of imparting birefringence and transparency are preferred. However, since it is difficult to impart all of the above-mentioned solubility, birefringence and transparency using one kind of acid dianhydride, the soluble polyimide of the present invention has a solubility imparting site in an organic solvent. It is preferable to use both the acid dianhydride having an acid dianhydride and the acid dianhydride having a birefringence imparting portion to the polyimide layer (however, each of the above sites is introduced in one molecule, and one kind of acid dianhydride is used. It is also possible to have a structure that imparts solubility, birefringence, and transparency. However, the solubility imparting site and the birefringence imparting site are sites that greatly contribute to the development of the solubility and birefringence of the soluble polyimide, and are not contradictory characteristics. The solubility imparting site does not contribute to the birefringence of the polyimide at all, but is considered to be the solubility imparting site because the solubility contribution of the polyimide is large. The same applies to the birefringence imparting site, and the contribution to birefringence is greater than the solubility of polyimide, so it is considered to be a birefringence imparting site.

  Examples of acid dianhydrides that impart solubility to polyimide include bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (2,3-dicarboxyphenyl) sulfide dianhydride, 2,2- Bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropanoic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propanoic dianhydride Etc. Two or more of these acid dianhydrides can be used. In particular, in view of providing solubility in an organic solvent, it is preferable to select 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanoic acid dianhydride.

  Examples of the acid dianhydride that imparts birefringence to the polyimide include pyromellitic dianhydride, 2,5-difluoropyromellitic dianhydride, 2-fluoropyromellitic dianhydride, 2, 5-bistrifluoromethylpyromellitic dianhydride, 2-trifluoromethylpyromellitic dianhydride, para-terphenyl-3,4,3 ″, 4 ″ -tetracarboxylic dianhydride, 3,3 ′ , 4,4'-benzophenonetetracarboxylic dianhydride, 1,4-hydroquinone dibenzoate-3.3 ', 4,4'-tetracarboxylic dianhydride, 3,3', 4,4 ' -Biphenyltetracarboxylic dianhydride, 2,2'-bistrifluoromethyl-3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2'-difluoro-3,3', 4 4'-Bife Nyltetracarboxylic dianhydride, 2,2'-dibromo-3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2'-diphenyl-3,3', 4,4'- Biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetra Carboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3′-meta-terphenyl-3,3 ″, 4,4 ″ -tetracarboxylic dianhydride, 2 , 2-bis (4-trimellitic acid monoester acid phenyl) propanoic acid dianhydride, 2,2-bis (4-trimellitic acid monoester acid phenyl) -1,1,1,3,3,3- Hexafluoropropanoic acid dianhydride, p-bifu Phenyl bis (trimellitic acid monoester acid anhydride), p-methylphenylene bis (trimellitic acid monoester acid anhydride), p-chlorophenylene bis (trimellitic acid monoester acid anhydride), p-fluorophenylene bis ( Trimellitic acid monoester acid anhydride), p-isopropylphenylenebis (trimellitic acid monoester acid anhydride), p- (t-butyl) phenylenebis (trimellitic acid monoester acid anhydride), p- (2 , 5-dichlorophenylene) bis (trimellitic acid monoester acid anhydride), p- (2,5-difluorophenylene) bis (trimellitic acid monoester acid anhydride), p- (2,5-dimethylphenylene) Bis (trimellitic acid monoester anhydride), p- (2,3,5-trichlorophenylene) bis Trimellitic acid monoester acid anhydride), p- (2,3,5-trifluorophenylene) bis (trimellitic acid monoester acid anhydride), p- (2,3-dimethylphenylene) bis (trimellitic acid) Monoester acid anhydride), 4,4'-biphenylenebis (trimellitic acid monoester acid anhydride), 1,4-naphthalene bis (trimellitic acid monoester acid anhydride), 2,6-naphthalene bis (trimethyl acid) Merit acid monoester anhydride) and the like. In view of providing birefringence to the polyimide layer, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-biphenylbis (trimellitic acid monoester acid It is preferable to select (anhydride). Among these, p-biphenylbis (trimellitic acid monoester acid anhydride) is particularly preferable from the viewpoint of transparency.

  The diamines that can be used in the present invention have a balance with the acid dianhydride used, and are not particularly limited, but those that can impart solubility by the synthesized polyimide, or birefringence in the polyimide layer, Or it is preferable that it can provide transparency. For example, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 2,2′-bis (trichloromethyl) -4,4′-diaminobiphenyl, 2,2′-bis (tribromo Methyl) -4,4'-diaminobiphenyl, 2,2'-difluoro-4,4'-diaminobiphenyl, 2,2'-dibromo-4,4'-diaminobiphenyl, 2,2'-dichloro-4, 4'-diaminobiphenyl and the like can be mentioned. These diamines are preferable from the viewpoint of imparting birefringence to a polyimide layer formed from a synthesized polyimide. In particular, it is preferable to select 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl in terms of imparting solubility to the synthesized polyimide.

The composition ratio between the general formula (1) and the general formula (2) is preferably x ₁ : y ₁ = 80: 20 to 45:55. x ₁ : y ₁ = 80: 20 to 55:45 is more preferable, and x ₁ : y ₁ = 80: 20 to 60:40 is particularly preferable. Composition ratio x _1: y ₁ = 80: when 20 x ₁ is greater y ₁ is less than the birefringence decreases, composition ratio x _1: y ₁ = 45: smaller x ₁ than 55 y ₁ Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

The composition ratio of the general formula (3) and the general formula (4) is preferably x ₂ : y ₂ = 95: 5 to 60:40. _{x 2: y 2 = 90:} 10~65: 35 and more _{preferably, x 2: y 2 = 80} : 20~65: 35 is particularly preferred. Composition ratio x _2: y ₂ = 95: If x ₂ than 5 larger y ₂ is small, the birefringence is small, composition ratio x _2: y ₂ = 60: small x ₂ than 40 y ₂ Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

The composition ratio of the general formula (5) and the general formula (6) is preferably x ₃ : y ₃ = 90: 10 to 60:40. x ₂ : y ₂ = 90: 10 to 65:35 is more preferable, and x ₁ : y ₁ = 90: 10 to 70:30 is particularly preferable. Composition ratio x _3: y ₃ = 90: If x ₃ than 10 large y ₃ is small, the birefringence is small, composition ratio _{x 3: y 3 = 60:} 40 x 3 small y ₃ than Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

The composition ratio between the general formula (7) and the general formula (8) is preferably x ₄ : y ₄ = 80: 20 to 45:55. _{x 4: y 4 = 80:} 20~55: 45 and more _{preferably, x 4: y 4 = 80} : 20~60: 40 is particularly preferred. Composition ratio x _4: y ₄ = 80: If x ₄ is larger y ₄ is smaller than 20, the birefringence is small, composition ratio _{x 4: y 4 = 45:} 55 x 4 small y ₄ than Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

The composition ratio of the general formula (9) and the general formula (10) is preferably x ₅ : y ₅ = 95: 5 to 60:40. x ₅ : y ₅ = 90: 10 to 65:35 is more preferable, and x ₅ : y ₅ = 80: 20 to 65:35 is particularly preferable. Composition ratio x _5: y ₅ = 95: If x ₅ than 5 larger y ₅ is small, the birefringence is small, composition ratio x _5: y ₅ = 60: is x ₅ than 40 small y ₅ Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

The composition ratio between the general formula (11) and the general formula (12) is preferably x ₆ : y ₆ = 90: 10 to 60:40. x ₆ : y ₆ = 90: 10 to 65:35 is more preferable, and x ₆ : y ₆ = 90: 10 to 70:30 is particularly preferable. Composition ratio x _6: y ₆ = 90: If y ₆ larger x ₆ than 10 is small, the birefringence is small, composition ratio x _6: y ₆ = 60: small x ₆ than 40 y ₆ Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

  The weight average molecular weight of the soluble polyimide is preferably 30,000 or more and 200,000 or less as measured by GPC in terms of PEG (polyethylene glycol). If the weight average molecular weight is less than 30,000, there may be a problem in durability. Moreover, since the solubility to an organic solvent will fall if a weight average molecular weight is 200,000 or more, it may be difficult to use for the use which melt | dissolves a soluble polyimide in an organic solvent.

  Furthermore, the imidation ratio of the soluble polyimide is preferably 80% or more. If it is less than 80%, it is not preferable in terms of transparency and birefringence. Preferably it is 90% or more, More preferably, it is 95% or more, More preferably, it is 99% or more.

  Next, a method for producing polyimide will be described. The method for producing polyimide generally includes three steps of (1) polymerization of polyamic acid, (2) imidation of polyamic acid, and (3) precipitation of polyimide resin. Not a thing.)

(1) Polymerization of polyamide acid The method for producing polyamide acid is not limited to the following method, and various methods can be used. An example is shown below.

  Dispersing the acid dianhydride in the reaction solvent in which the diamine is dissolved and stirring to completely dissolve and polymerize the acid dianhydride, dissolving and / or dispersing the acid dianhydride in the reaction solvent, and then using the diamine There are a polymerization method and a polymerization method by reacting a mixture of acid dianhydride and diamine in a reaction solvent, and a known polymerization method may be used.

  The reaction time is preferably about 1 to 5 hours. On the other hand, the reaction is preferably performed until the viscosity of the polyamic acid solution is 5 Pa · s or more, more preferably 10 Pa · s or more, and most preferably 20 Pa · s or more. If the viscosity of the polyamic acid solution is too low, the handleability may be reduced. The viscosity is kept at 23 ° C. in a water bath kept at 23 ° C., and the rotor is No. 7 can be measured at 4 rpm.

  The reaction apparatus is preferably equipped with a temperature adjusting apparatus for controlling the reaction temperature, and the reaction solution temperature is preferably 60 ° C. or less, and more preferably 40 ° C. or less in terms of controlling the reaction.

  The solvent used for the polymerization of the polyamic acid is preferably a solvent capable of dissolving the acid dianhydride and diamine used, and more preferably a solvent capable of dissolving the produced polyamic acid. For example, ureas such as tetramethylurea, N, N-dimethylethylurea, dimethylsulfoxide, diphenylsulfone, sulfoxides or sulfones such as tetramethylsulfone, N, N-dimethylacetamide (DMAc), N, N-dimethyl An aprotic solvent of formamide (DMF), N, N′-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyllactone, hexamethylphosphate triamide, or phosphorylamides, Examples include alkyl halides such as chloroform and methylene chloride, aromatic hydrocarbons such as benzene and toluene, phenols such as phenol and cresol, and ethers such as dimethyl ether, diethyl ether, and p-cresol methyl ether. It can usually be used in combination but employing these solvents alone, two or more depending on necessity. Of these, amides such as DMF, DMAc and NMP are preferably used. Moreover, the organic solvent which can fully melt | dissolve the polyimide finally obtained is preferable.

  From the viewpoint of handling, it is preferable that the polyamic acid in the polyamic acid solution is dissolved by 5 to 50 wt%, preferably 10 to 40 wt% of the polyamic acid in the reaction solvent.

  The molar ratio of acid dianhydride and diamine used in the polymerization reaction of the polyamic acid solution is preferably 0.9 or more and 1.5 or less, more preferably 0, when calculated by the following formula. .95 or more and 1.3 or less, particularly preferably 0.98 or more and 1.2 or less, unreacted acid dianhydride or diamine in a polyimide resin obtained from a polyamic acid solution It is preferable in reducing the amount.

(2) Imidization of polyamic acid A method for imidizing polyamic acid is described. Various known methods can be used as a method for imidizing the polyamic acid. For example, a thermal imidation method that thermally dehydrates and closes a ring or a chemical imidization method that uses a dehydrating agent can be used.

  The thermal imidization method is generally performed by adding an azeotropic solvent such as toluene azeotropically with water generated during the imidation reaction to the polyamic acid solution and then heating. In the thermal imidization method, an imidization accelerator can be used in combination.

  In general, the chemical imidization method is preferable in that the imidization reaction proceeds more easily than the thermal imidization method, the decomposition of the polyamic acid during heating is suppressed, and imidization can be performed.

  In the chemical imidization method, it is preferable to use an imidization accelerator in that the reaction is completed in a short time. As the imidization accelerator, various tertiary amines can be used. In particular, heterocyclic tertiary amines such as pyridine, quinoline, and isoquinoline are preferable in that a polyimide having a high imidation ratio can be obtained.

  The temperature for imidization is 40 ° C. to the boiling point of the reaction solvent used for imidization, more preferably 50 ° C. to the boiling point of the reaction solvent used for imidization, and the heating time is 0.5 to 20 hours. It is preferable that When the temperature is lower than 40 ° C., the imidization ratio may be lowered, which is not preferable. On the other hand, heating at 150 ° C. or lower is preferable in order to prevent the polyimide from being colored.

  Examples of the dehydrating agent used in the chemical imidization method include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides. It is preferable to use acetic anhydride from the viewpoint that it is suitable for the precipitation step of the polyimide resin.

  The amount of the imidization accelerator to be added to the polyamic acid is 0.5 to 5, more preferably 1 to 5, and more preferably 2 to 4 when the number of moles of the polyamic acid is 1. preferable. If the amount of the imidization accelerator is too smaller than the above range, imidization may not proceed sufficiently. On the other hand, if it is too large, although it depends on the poor solvent used in the precipitation of the polyimide resin powder, it tends to reduce the imidization rate.

  The amount of the dehydrating agent added to the polyamic acid is preferably 1.2 to 4.0 when the number of moles of the polyamic acid is 1. If the amount of the dehydrating agent is less than 1.2, imidization may not proceed sufficiently. Conversely, if it exceeds 4, the molecular weight may be lowered or colored.

(3) Precipitation of polyimide resin It describes about the precipitation method of imide resin. As a method for precipitating the polyimide resin from the solution containing the polyimide resin obtained as described in (1) and (2) above, various known methods can be selected. For example, polyimide resin, dehydrating agent, imidization promotion The polyimide resin can be obtained in a solid state by introducing a polyimide resin solution containing an agent or the like into the poor solvent of the polyimide resin, or by introducing the poor solvent into the polyimide resin solution. As a method of adding the poor solvent to the polyimide resin solution, there are a method of adding it in droplets or a method of adding it in a thread form, but there is no particular limitation as long as the polyimide resin is precipitated in the poor solvent. . The shape at the time of precipitation can be deposited in various forms such as a thread, a powder, and a flake. Further, these can be used after being pulverized if necessary.

  The poor solvent of the polyimide resin used in the present invention is not particularly limited, but is preferably mixed with a reaction solvent used as a solvent for dissolving the polyimide resin, for example, water, methyl alcohol, ethyl alcohol, isopropyl alcohol, Examples include ethylene glycol, triethylene glycol, 2-butyl alcohol, 2-propyl alcohol, 2-hexyl alcohol, cyclopentyl alcohol, cyclohexyl alcohol, phenol, and t-butyl alcohol. Among the above alcohols, secondary or tertiary alcohols such as isopropyl alcohol, 2-butyl alcohol, 2-pentyl alcohol, phenol, cyclopentyl alcohol, cyclohexyl alcohol, and t-butyl alcohol increase the imidization ratio of the resulting polyimide resin. From the viewpoint of stabilization, 2-propyl alcohol is more preferable. The amount of the poor solvent is preferably extracted in an amount of 2 times or more, more preferably 3 times or more of the polyimide resin solution.

  By simply depositing and separating the polyimide resin from the polyimide resin solution, it may be difficult to obtain a polyimide resin having a desired shape (a shape that is easily dissolved in an organic solvent) after drying. This is because the polyimide resin contains a large amount of reaction solvent. By washing the polyimide resin with the poor solvent, a desired polyimide resin containing almost no reaction solvent can be obtained.

  The method for drying the solidified resin solidified in the present invention may be vacuum drying or hot air drying. However, when used for optical purposes, coloring at the time of drying may be a problem, so it is desirable to carry out at 150 ° C. or lower.

  The soluble polyimide of the present invention can be used for forming a laminated member, an optical compensation member and the like by using a polyimide solution obtained by dissolving in a solvent as a polyimide coating solution. The laminated member, the optical compensation member, etc. may be unstretched or formed with stretching. When extending | stretching, since Tg of soluble polyimide is comparatively high, it is preferable to extend before drying or in the middle of drying.

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

(Example 1)
In this example, a glass separable flask was provided as a reaction vessel, two paddle blades were provided as a stirring device in the separable flask, and a device having a cooling capacity of 20.9 kJ / min was provided as a cooling device. A polyamic acid was produced using a reactor. During the polymerization reaction, in order to prevent moisture from being mixed, the polymerization reaction was carried out by flowing nitrogen gas dehydrated by passing through silica gel at a rate of 0.05 L / min.

  The separable flask was charged with 223.5 g of N, N-dimethylformamide (DMF) as a solvent for polymerization, and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) was added thereto. ) 40.0 g (0.125 mol) is dissolved. To this solution, 6FDA 33.3 (0.075 mol) g, 3,3′-4,4′-biphenyltetracarboxylic dianhydride (BPDA) 14.7 g (0.050 mol) (6FDA: BPDA = 6 : 4) was added and stirred to dissolve completely. After complete dissolution, the mixture was stirred to increase the polymerization viscosity to 80 Pa · s. The viscosity of the polyamic acid solution was kept for 1 hour in a water bath kept at 23 ° C., and the viscosity at that time was measured with a B-type viscometer. 7 was measured at a rotational speed of 4 rpm. In addition, the preparation density | concentration of the aromatic diamine compound and aromatic tetracarboxylic dianhydride in this reaction solution was 30 weight% with respect to all the reaction liquids.

  DMF was added to the above solution to adjust the solid content concentration to 15% by weight, and 30 g of pyridine as an imidization catalyst (molar ratio of imidization accelerator / amide group in polyamic acid = 3) was completely dispersed. To the dispersed solution, 15.3 g (molar ratio of dehydrating agent / amide group in polyamic acid = 1.2) of acetic anhydride was added at a rate of 1 g per minute and stirred for another 30 minutes. After stirring, the internal temperature was raised to 100 ° C., and heating and stirring were performed for 5 hours.

  After the polyimide resin solution was added to a 5-L 2-propyl alcohol bath stirred with a stirring blade for 200 revolutions or more, stirring was continued for about 12 hours.

  Thereafter, the polyimide slurry was taken out, and 5 L of 2-propyl alcohol was further added to completely extract the solid content. And solid content was heat-dried at 100 degreeC with the vacuum dryer, and it took out as polyimide resin.

(Evaluation methods)
(Solubility)
In the solubility test, DMF and MIBK were dispersed in a solution so that the solid content was 15%, and after the polyimide resin was completely dispersed in the solution, it was placed in a temperature-controlled room maintained at 23 ° C. for 24 hours. It was confirmed that it was completely dissolved. The results are shown in Table 1 as ◯ for those completely dissolved and x for those not completely dissolved. In addition, the solubility of the soluble polyimide of the present invention is not limited to the solubility in the specific solvent. However, as a solvent for dissolving polyimide, at the same time as dissolving the soluble polyimide of the present invention, in addition, in the step of forming a polyimide layer on the support, the influence on the support made of a polymer (for example, the characteristics and uniformity are impaired. It is preferable to use one having a low degree of dissolution or swelling.

(Birefringence)
A polyimide solution containing 10% by weight of polyimide was prepared by dissolving polyimide resin in MIBK or DMF. As a polyimide solution used for casting, a MIBK solution was used as a polyimide dissolved in MIBK, and a DMF solution was used as a polyimide dissolved only in DMF. The polyimide resin solution was applied as a polyimide resin solution film having a uniform film thickness on a glass plate with a bar coater, dried in a hot air oven heated to 50 ° C. for 10 minutes, and then heated in a hot air oven heated to 200 ° C. And dried for 60 minutes. Thereafter, the film was peeled off from the glass to obtain a polyimide film having a thickness of 20 μm. Birefringence measurement was performed using the film. The method of birefringence measurement is shown below.

  In the film, the direction having the largest refractive index in the plane was defined as the X direction, the direction perpendicular to the X direction was defined as the Y direction, and the thickness direction was defined as the Z direction. As shown in FIG. 1, a trapezoidal piece was cut out parallel to the X and Y directions to obtain a sample for measuring birefringence in which the height of the trapezoidal piece (hereinafter referred to as d) was about 200 to 300 μm.

  The birefringence measurement was performed using a sodium lamp D line (λ: 589 nm). A sample for measuring the birefringence of the trapezoidal piece is erected as shown in FIG. 2 (the length of the lower side of the trapezoidal piece> the length of the upper side), and the monochromatic polarized light from the lower side of the sample is X direction and Z direction or Y direction and Z direction Irradiate perpendicular to Monochromatic polarized light was incident at an angle of 45 ° with respect to the Z direction side of the measurement sample, and the measurement sample slope was observed from above (A in the figure) under crossed Nicols. By counting the number (m) of interference fringes appearing on the slope, birefringence can be calculated from the phase difference when the height (d) of the measurement sample is the optical path length. In this way, the birefringence of the two birefringence measurement samples was calculated. However, when the interference fringes appearing on the slope are not observed almost parallel to the thickness direction, the major factor is that the cross section of the sample is oblique. When interference fringes are not observed almost parallel to the thickness direction, it is necessary to prepare the sample again.

In-plane and thickness-direction birefringence (sometimes referred to simply as birefringence in the present invention) in the present invention was calculated by the following equation. However, X-direction, Y-direction, the refractive index in the Z direction and _{n x, n y, n z} . The birefringence in the X and Z directions (Δn _xz ), the height of the measurement sample (d _x ), the number of interference fringes ( _mx ), and the birefringence in the Y and Z directions (Δn _yz ) The measurement sample height (d _y ) and the number of interference fringes (m _y ) are used.
Birefringence = (Δn _xz + Δn _yz ) / 2
Δn _xz = n _x −n _z = m _x × λ / d _{x
△ n yz = n y -n z} = m y × λ / d y
The birefringence values are listed in Table 1.

(Coloring amount N)
The polyimide film used in the birefringence measurement was measured with an ultraviolet-visible absorptiometer (JASCO Ubset-30). The coloring amount N is represented by the following formula:

It is calculated from. The evaluation results are shown in Table 1.

(Example 2)
Implemented except that 6FDA 33.3 (0.075 mol) g and pyromellitic dianhydride (PMDA) 10.9 (0.05 mol) g (6FDA: PMDA = 6: 4) were used as the acid dianhydride. Prepared as in Example 1.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Example 3)
Example 1 except that 6FDA 38.6 (0.087 mol) g and pyromellitic dianhydride (PMDA 8.2 (0.038 mol) g (6FDA: PMDA = 7: 3)) were used as the acid dianhydride. And manufactured in the same manner.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 4
Implemented except using 6FDA 44.4 (0.100 mol) g, pyromellitic dianhydride (PMDA) 5.5 (0.025 mol) g (6FDA: PMDA = 8: 2) as acid dianhydride Prepared as in Example 1.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Example 5)
6FDA33.3 (0.075 mol) g as acid dianhydride, p-phenylenebis (trimellitic acid monoester anhydride) (TMHQ) 22.9 (0.05 mol) g (6FDA: TMHQ = 6: Prepared in the same manner as in Example 1 except that 4) was used.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Example 6)
6FDA 27.9 (0.063 mol) g, 2,2-bis (4-trimellitic acid monoester phenyl) propanoic acid dianhydride (ESDA) 36.0 (0.063 mol) g (as acid dianhydride) 6FDA: ESDA = 5: 5) was used in the same manner as in Example 1 except that 6) was used.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Example 7)
6FDA 38.6 (0.087 mol) g as acid dianhydride, p-phenylenebis (trimellitic acid monoester anhydride) (TMHQ) 17.2 (0.038 mol) g (6FDA: TMHQ = 7: Manufactured in the same manner as in Example 1 except that 3) was used.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(Comparative Example 1)
It was produced in the same manner as in Example 1 except that 6FDA55.5 (0.125 mol) g was used as the acid dianhydride.

  The polyimide resin was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

(R ⁵ = hydrogen, halogen element, halogenated alkyl group, aromatic group, R ⁶ = hydrogen, halogen element, halogenated alkyl group, aromatic group, and R ⁵ and R ⁶ are the same or different. (N1 = 1-3, n2 = 1-3, Ar is an aromatic group)
5) Containing the structures of the following general formula (7) and general formula (8), and when the respective contents are expressed as x ₄ and y ₄ , x ₄ : y ₄ = 80: 20 to 45:55 The soluble polyimide according to 1) or 2), which is characterized in that it exists.

The composition ratio of the general formula (5) and the general formula (6) is preferably x ₃ : y ₃ = 90: 10 to 60:40. x ₃ : y ₃ = 90: 10 to 65:35 is more preferable, and x ₃ : y ₃ = 90: 10 to 70:30 is particularly preferable. Composition ratio x _3: y ₃ = 90: If x ₃ than 10 large y ₃ is small, the birefringence is small, composition ratio _{x 3: y 3 = 60:} 40 x 3 small y ₃ than Is large, the solubility of polyimide in an organic solvent or the transparency when formed into a film is poor.

The solvent used for the polymerization of the polyamic acid is preferably a solvent capable of dissolving the acid dianhydride and diamine used, and more preferably a solvent capable of dissolving the produced polyamic acid. For example, ureas such as tetramethylurea, N, N-dimethylethylurea, dimethylsulfoxide, diphenylsulfone, sulfoxides or sulfones such as tetramethylsulfone, N, N-dimethylacetamide (DMAc), N, N-dimethyl Formaldehyde (DMF), N, N-diethylacetamide , N-methyl-2-pyrrolidone (NMP), γ-butyllactone, amides such as hexamethylphosphoric triamide, or phosphorylamide aprotic solvent, chloroform And alkyl halides such as methylene chloride, aromatic hydrocarbons such as benzene and toluene, phenols such as phenol and cresol, and ethers such as dimethyl ether, diethyl ether, and p-cresol methyl ether. Typically it may be used in combination but employing these solvents alone, two or more depending on necessity. Of these, amides such as DMF, DMAc and NMP are preferably used. Moreover, the organic solvent which can fully melt | dissolve the polyimide finally obtained is preferable.

Claims (13)

  The birefringence in the in-plane and thickness direction of the polyimide layer obtained by casting and drying a polyimide solution dissolved in the organic solvent is at least 0.04, A soluble polyimide that is 15 or less. It contains the structure of the following general formula (1) and general formula (2), and when each content is expressed as x ₁ and y ₁ , x ₁ : y ₁ = 80: 20 to 45:55 The soluble polyimide according to claim 1.

(R ¹ = H, F, CF ₃ , R ² = H, F, CF ₃ and R ₁ and R ₂ may be the same or different. Ar is an aromatic group.) It contains the structures of the following general formula (3) and general formula (4), and when the respective contents are expressed as x ₂ and y ₂ , x ₂ : y ₂ = 95: 5 to 60:40 The soluble polyimide according to claim 1.

(R ³ =

R ⁴ = —Cl, —F, —CH ₃ , —C (CH ₃ ) ₃ , —CH (CH ₃ ) ₂ , n = 1 to 4, Ar is an aromatic group. ) It contains the structure of the following general formula (5) and general formula (6), and when the respective contents are expressed as x ₃ and y ₃ , x ₃ : y ₃ = 90: 10 to 60:40 The soluble polyimide according to claim 1.

(R ⁵ = H, F, CF ₃ , R ⁶ = H, F, CF ₃ and R ₁ and R ₂ may be the same or different. N1 = 1 to 3, n2 = 1 to 3 , Ar is an aromatic group.) It contains the structures of the following general formula (7) and general formula (8), and when the respective contents are expressed as x ₄ and y ₄ , x ₄ : y ₄ = 80: 20 to 45:55 The soluble polyimide according to any one of claims 1 and 2.

(R ¹ = H, F, CF ₃ , R ² = H, F, CF ₃ and R ₁ and R ₂ may be the same or different.) It contains the structures of the following general formula (9) and general formula (10), and when the respective contents are expressed as x ₅ and y ₅ , x ₅ : y ₅ = 95: 5 to 60:40 The soluble polyimide according to any one of claims 1 and 3.

(R ³ =

^{R 4 = -Cl, -F, -CH} 3, -C (CH 3) 3, -CH (CH 3) 2
n = 1-4) It contains the structures of the following general formula (11) and general formula (12), and when the respective contents are expressed as x ₆ and y ₆ , x ₆ : y ₆ = 90: 10 to 60:40 The soluble polyimide according to any one of claims 1 and 4, wherein:

(R ⁵ = H, F, CF ₃ , R ⁶ = H, F, CF ₃ and R ⁵ and R ⁶ may be the same or different. N1 = 1 to 3, n2 = 1 to 3 .)   The laminated member which dried the polyimide solution obtained by melt | dissolving the soluble polyimide of any one of Claims 1-7 after casting on a support body, and formed the polyimide layer on the support body.   An optical compensation member in which a polyimide solution obtained by dissolving the soluble polyimide according to claim 1 is cast on a support and then dried to form a polyimide layer on the support.   The laminated member according to claim 8, wherein the polyimide layer has a thickness of 1 μm or more and less than 40 μm.   The optical compensation member according to claim 9, wherein the polyimide layer has a thickness of 1 μm or more and less than 40 μm.   The polyimide solution obtained by melt | dissolving the soluble polyimide of any one of Claims 1-7.   The polyimide coating liquid obtained by melt | dissolving the soluble polyimide of any one of Claims 1-7.

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