JP4802934B2 - Alicyclic polyimide copolymer and method for producing the same - Google Patents

Description

The present invention relates to a polyimide copolymer in which the repeating unit of the polyimide main chain is an alicyclic system and a varnish thereof, a polyimide molded body formed by molding the varnish, a plastic substrate formed of the molded body, and an electric / electric device provided with the substrate. The present invention relates to an electronic component and a method for producing the polyimide copolymer.
More specifically, the present invention relates to a solvent-soluble alicyclic polyimide copolymer excellent in transparency, heat resistance and toughness and its varnish, and a polyimide molding excellent in transparency, heat resistance and toughness formed by molding the varnish. Body, flexible plastic substrate made of the molded body, and electric / electronic components (electrical insulating film and liquid crystal display, organic electroluminescence display, electronic paper, solar cell, etc. in various electronic devices) provided with the substrate, and the polyimide The present invention relates to a method for producing a copolymer.

In general, polyimide resin has not only high heat resistance, but also high mechanical strength, wear resistance, dimensional stability, chemical resistance, etc. Widely used in the electrical and electronic industries such as substrate base film.
In recent years, with the advent of an advanced information society, materials having both heat resistance and transparency are required in the field of optical communication such as optical fibers and optical waveguides, and in the field of display devices such as liquid crystal alignment films and protective films for color filters. . In particular, in the field of display devices, a glass substrate is being considered as an alternative to a lightweight and flexible plastic substrate, and displays that can be bent or rolled are being actively developed. In this field, there is a strong demand for the development of resin materials that are excellent in toughness in addition to transparency and heat resistance.

  However, in general, a polyimide resin is essentially yellowish brown due to intramolecular conjugation or formation of a charge transfer complex. As a solution to this problem, a method of imparting transparency by using a fluorinated polyimide resin, a semi-alicyclic or a fully alicyclic polyimide resin has been proposed (Patent Documents 1 to 3).

  Although the method using the fluorinated polyimide resin exhibits good transparency, its production cost is high, and it is problematic in that it lacks versatility in industrial use.

  In a method using a semi-alicyclic or fully alicyclic polyimide resin, since the polyimide resin is usually hardly soluble in a solvent, it is necessary to use a precursor polyamic acid varnish for molding processing. is there. However, when the polyamic acid varnish is molded, there is a problem that the transparency in the visible light region is remarkably impaired because it is exposed to a high temperature to cause thermal decomposition or the like. For this reason, in applications where transparency is required, there has been an expectation for the development of a solvent-soluble fully alicyclic polyimide resin that replaces the polyamic acid varnish.

However, most conventional solvent-soluble fully alicyclic polyimide resins have relatively low molecular weights, and therefore tend to have lower desired heat resistance and mechanical properties (particularly toughness). was there.
The reason why the molecular weight is low is that during the imidization reaction during the production of the fully alicyclic polyimide resin, the amic acid produced as an intermediate and the alicyclic diamine form a strong salt, and the reaction hardly proceeds. Is the cause.

For example, when 1,2,4,5-cyclohexanetetracarboxylic dianhydride is used for the tetracarboxylic acid component, a reported example of obtaining a tough all-cyclocyclic polyimide resin that can be used as a substrate material is There are almost no reports of polyimide resins consisting of 4,4′-diaminodicyclohexylmethane (Patent Document 4).
However, the polyimide resin composed of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 4,4'-diaminodicyclohexylmethane reacts because the solution thickens and gels rapidly during the imidation reaction. Control tends to be difficult, and there is a problem in industrial production. Further, even if the polyimide resin is tried to be film-formed, there is a problem that workability is remarkably poor.
In addition, although a method of suppressing the thickening by a method using a mixed solvent has been reported (Patent Document 5), there is an adverse effect of decreasing the degree of polymerization, and a satisfactory result is not always obtained.
Therefore, there has been a strong demand for a solvent-soluble fully alicyclic polyimide having heat resistance, transparency and toughness that can be used for a flexible display substrate, and a method capable of stably producing the same.

JP-A-11-106508 JP 2002-146021 A JP 2002-348374 A JP 2005-15629 A JP 2004-359941 A

  An object of the present invention is to provide a solvent-soluble alicyclic polyimide copolymer having a high degree of polymerization and a varnish capable of providing a polyimide molded body having excellent heat resistance, transparency and toughness that can be used for flexible display substrates and the like. The present invention provides a polyimide molded body having excellent heat resistance, transparency and toughness, a plastic substrate made of the molded body, an electric / electronic component including the substrate, and a method for producing the polyimide copolymer.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained the following findings (i) to (vi) in the examination process.
(I) (a) 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 4,4′-diamino-dicyclohexylmethane were subjected to imidization reaction in the presence of N, N-dimethylacetamide. When a large amount of salt is precipitated, a polyimide having a sufficient degree of polymerization cannot be obtained (Comparative Example 1).
(B) When the reaction solvent is replaced with N-methyl-pyrrolidone, the reaction proceeds with little salt precipitation, but the reaction system rapidly thickens and cannot be stirred. That is, control of reaction is difficult and it is difficult to manufacture industrially (Comparative Example 2).
(C) Even if the charged molar ratio of the tetracarboxylic dianhydride and the diamine is changed in the range of 1: 0.97 to 1.05 (molar ratio), only the same result can be obtained.
(Ii) 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 4,4′-diamino-dicyclohexylmethane combined with a dicarboxylic acid component represented by the following general formula (1), and use thereof When the imidization reaction is performed with the molar ratio limited to a specific range, the salt generated during the reaction dissolves in the reaction solvent at the initial stage of the reaction, and the reaction system rapidly increases in viscosity even if the imidization reaction proceeds. It is not recognized, and it can be manufactured stably.
(Iii) The polyimide copolymer in which the repeating unit of the polyimide main chain obtained by the production method of (ii) is an alicyclic system is soluble in an organic solvent and has a high degree of polymerization.
(Iv) The polyimide varnish obtained from the polyimide copolymer has good storage stability, no turbidity and high transparency.
(V) The polyimide molded body obtained by molding from the varnish is excellent in transparency, heat resistance and toughness.
(Vi) Since the molded body has the above-mentioned properties, it is suitable for plastic substrates, and can be used for electric / electronic parts such as liquid crystal displays, organic electroluminescence displays, electronic paper, solar cells, and electric insulating films.
The present invention has been completed based on such knowledge and provides the following items.

［式中、Ａは、炭素数２〜１３の二価の基を表す。］
一般式（２）

［式中、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、同一または異なって、水素原子、メチル基、エチル基、メトキシ基又はエトキシ基を表す。Ｙは、直接結合、−ＣＨ_２−、−Ｏ−、−Ｓ−、−ＳＯ₂ −、−Ｃ（＝Ｏ）−ＮＨ−、−Ｃ（−ＣＨ₃ ）₂ −、−Ｃ（−ＣＦ₃ ）₂ −又は−Ｃ（＝Ｏ）−から選ばれる二価の基を表す。］ (Item 1) In the presence of a reaction solvent, at least one tetracarboxylic acid component selected from the group consisting of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and its derivatives and the following general formula (1) Dicarboxylic acid component and at least one dicarboxylic acid component selected from the group consisting of derivatives thereof and an alicyclic diamine component represented by the following general formula (2) with respect to the tetracarboxylic acid component 100: An alicyclic polyimide copolymer obtained by carrying out an imidization reaction by heat dehydration at a charged molar ratio in the range of 0.1 to 10 and an alicyclic diamine component 97 to 105.
General formula (1)

[In formula, A represents a C2-C13 bivalent group. ]
General formula (2)

[Wherein, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group. Y is a direct bond, —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —NH—, —C (—CH ₃ ) ₂ —, —C (—CF ₃ ) Represents a divalent group selected from _2- or -C (= O)-. ]

(Item 2) The alicyclic structure according to Item 1, wherein the number of moles a of the tetracarboxylic acid component, the number of moles b of the dicarboxylic acid component, and the number of moles c of the alicyclic diamine component are in a relationship of 2a + b ≦ 2c. -Based polyimide copolymer.

(Item 3) The alicyclic polyimide copolymer according to Item 1 or 2, wherein the intrinsic viscosity of the alicyclic polyimide copolymer is 0.5 to 1.5 dL / g.

(Item 4) A polyimide varnish containing the alicyclic polyimide copolymer according to any one of Items 1 to 3 and an organic solvent.

(Item 5) A polyimide molded body obtained by molding the polyimide varnish according to Item 4.

(Item 6) The polyimide molded product according to item 5, wherein the polyimide molded product is in the form of a film, a film, or a sheet.

(Item 7) The polyimide molded product according to item 5 or 6, wherein the polyimide molded product has a glass transition temperature of 290 ° C or higher and an imidization ratio of 80% or higher.

(Item 8) A plastic substrate comprising the polyimide molded body according to any one of Items 5 to 7.

(Item 9) An electric / electronic component comprising the plastic substrate according to Item 8.

(Item 10) The electric / electronic component according to Item 9, wherein the electric / electronic component is a liquid crystal display, an organic electroluminescence display, electronic paper, a solar cell, or an electric insulating film.

［式中、Ａは、炭素数２〜１３の二価の基を表す。］
一般式（２）

［式中、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、同一または異なって、水素原子、メチル基、エチル基、メトキシ基又はエトキシ基を表す。Ｙは、直接結合、−ＣＨ_２−、−Ｏ−、−Ｓ−、−ＳＯ₂ −、−Ｃ（＝Ｏ）−ＮＨ−、−Ｃ（−ＣＨ₃ ）₂ −、−Ｃ（−ＣＦ₃ ）₂ −又は−Ｃ（＝Ｏ）−から選ばれる二価の基を表す。］ (Item 11) In the presence of a reaction solvent, at least one tetracarboxylic acid component selected from the group consisting of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and derivatives thereof and the following general formula (1) At least one dicarboxylic acid component selected from the group consisting of dicarboxylic acid anhydrides and derivatives thereof, and an alicyclic diamine component represented by the following general formula (2):
An alicyclic system characterized in that an imidization reaction is carried out by heat dehydration at a charged molar ratio in the range of dicarboxylic acid component 0.1 to 10 and alicyclic diamine component 97 to 105 with respect to tetracarboxylic acid component 100. A method for producing a polyimide copolymer.
General formula (1)

[In formula, A represents a C2-C13 bivalent group. ]
General formula (2)

[Wherein, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group. Y is a direct bond, —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —NH—, —C (—CH ₃ ) ₂ —, —C (—CF ₃ ) Represents a divalent group selected from _2- or -C (= O)-. ]

(Item 12) The method according to Item 11, wherein the number of moles a of the tetracarboxylic acid component, the number of moles b of the dicarboxylic acid component, and the number of moles c of the alicyclic diamine component are in a relationship of 2a + b ≦ 2c. .

(Item 13) The charging sequence of the reaction substrate (that is, the above-mentioned tetracarboxylic acid component, dicarboxylic acid component and alicyclic diamine component) is (i) the alicyclic represented by the general formula (2). After the diamine component is dissolved in the reaction solvent, (ii) at least one tetracarboxylic acid component selected from the group consisting of 1,2,4,5-cyclohexanetetrarubonic dianhydride and derivatives thereof is charged (dissolved) (Iii) Next, the above item 11 or item 12, which is the order in which at least one dicarboxylic acid component selected from the group consisting of the dicarboxylic acid anhydride represented by the general formula (1) and its derivative is charged. The manufacturing method as described in.

According to the present invention, a polyimide copolymer having a high polymerization degree and a solvent-soluble polyimide main chain repeating unit of an alicyclic system (a high polymerization degree solvent-soluble alicyclic polyimide copolymer) is obtained. be able to. The polyimide varnish obtained from the polyimide copolymer is highly stable over time, and hardly changes in properties such as gelation even when stored at room temperature for a long time (a high-quality polyimide varnish).
Furthermore, the polyimide molded body (film, sheet, membrane, etc.) produced from the varnish exhibits high transparency and high heat resistance, and further has high toughness. Since it has these performances, it can be suitably used as a flexible display substrate or the like.
Moreover, according to this production method, since there is almost no precipitation of a salt of amic acid and an alicyclic diamine, a sudden change in viscosity (viscosity increase) of the reaction system can be controlled (or suppressed). An imidization reaction can be performed. As a result, a solvent-soluble alicyclic polyimide copolymer having a high degree of polymerization can be efficiently produced.

<Tetracarboxylic acid component>
The tetracarboxylic acid component according to the present invention is at least one selected from the group consisting of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and derivatives thereof.
The 1,2,4,5-cyclohexanetetracarboxylic dianhydride can be obtained by, for example, 1,2,4,5-cyclohexane obtained by a production method disclosed in JP-A-8-325196 and JP-A-8-325201. Tetracarboxylic acid is dehydrated in acetic anhydride at 40 ° C. for 2 to 5 hours, and then the obtained slurry-like acetic anhydride solution is filtered off and the wet crystals are dried under reduced pressure to obtain a high-purity white solid. Can be obtained as Since 1,2,4,5-cyclohexanetetracarboxylic dianhydride obtained by this method contains almost no coloring component, it can be suitably used as a raw material for the alicyclic polyimide copolymer of the present invention. .

  The “derivative of 1,2,4,5-cyclohexanetetracarboxylic dianhydride” means 1,2,4,5-cyclohexanetetracarboxylic acid, which is a hydrous acid of tetracarboxylic dianhydride, Derivatives such as acid chlorides of carboxylic acids and esters of the tetracarboxylic acids and lower alcohols having 1 to 4 carbon atoms. These derivatives can also be used alone or in admixture of two.

  Among the above tetracarboxylic acid components, 1,2,4,5-cyclohexanetetracarboxylic dianhydride is particularly recommended from the viewpoints of polymerizability, purity, and hue (number of colors).

<Dicarboxylic acid component>
The dicarboxylic acid component according to the present invention is at least one selected from the group consisting of the dicarboxylic acid anhydride represented by the general formula (1) and derivatives thereof. A in the general formula (1) has 2 to 13 carbon atoms, preferably a divalent group having 6 to 8 carbon atoms. The divalent group is preferably an aliphatic organic group or an alicyclic organic group, more preferably an alicyclic organic group, particularly an alicyclic ring represented by the following general formulas (a) to (d). Group organic groups are recommended.

［式中、Ｘは、メチル基、エチル基、メトキシ基又はエトキシ基を表す。ｎは、０〜２の整数を表す。ｎ個のＸは、互いに同一又は異なっても良い。］ Formula (a)

[Wherein, X represents a methyl group, an ethyl group, a methoxy group or an ethoxy group. n represents an integer of 0 to 2. The n Xs may be the same or different from each other. ]

［式中、Ｘ及びｎは、一般式（ａ）におけると同義である。］ General formula (b)

[Wherein, X and n are as defined in general formula (a). ]

［式中、Ｘ及びｎは、一般式（ａ）におけると同義である。］ Formula (c)

[Wherein, X and n are as defined in general formula (a). ]

［式中、Ｘ及びｎは、一般式（ａ）におけると同義である。］
General formula (d)

[Wherein, X and n are as defined in general formula (a). ]

Specific examples of the aliphatic dicarboxylic acid component include succinic anhydride and maleic anhydride, and examples of the alicyclic dicarboxylic acid component include 1,2-cyclopentanedicarboxylic anhydride, 1,2-cyclohexanedicarboxylic acid. Anhydride, 3-methyl-1,2-cyclohexanedicarboxylic acid anhydride, 4-methyl-1,2-cyclohexanedicarboxylic acid anhydride, 1-cyclohexene-1,2-dicarboxylic acid anhydride, 3-methyl-1- Cyclohexene-1,2-dicarboxylic acid anhydride, 4-methyl-1 cyclohexene-1,2-dicarboxylic acid anhydride, 3-cyclohexene-1,2-dicarboxylic acid anhydride, 3-methyl-3-cyclohexene-1, 2-dicarboxylic anhydride, 4-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 4-cyclohexene-1, -Dicarboxylic anhydride, 3-methyl-4-cyclohexane-1,2-dicarboxylic anhydride, 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic acid Anhydride, norbornane-2,3-dicarboxylic acid anhydride, 5-methyl-5-norbornene-2,3-dicarboxylic acid anhydride, 5-methylenenorbornane-2,3-dicarboxylic acid anhydride, 5-methylnorbornane- 2,3-dicarboxylic acid anhydride, bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic acid anhydride, bicyclo [2.2.2] octane-2,3-dicarboxylic acid anhydride Examples of the aromatic dicarboxylic acid component include 2,3-benzophenone dicarboxylic acid anhydride, 3,4-benzophenone dicarboxylic acid anhydride, 2,3-dicar Xiphenylphenyl ether anhydride, 2,3-biphenyl dicarboxylic acid anhydride, 3,4-biphenyl dicarboxylic acid anhydride, 1,2-naphthalenedicarboxylic acid anhydride, 2,3-naphthalenedicarboxylic acid anhydride, 1,8 -Naphthalene dicarboxylic acid anhydride etc. are illustrated.
These dicarboxylic acid components may be used alone or in combination of two or more.

Among the above, alicyclic and aliphatic dicarboxylic acid components are preferable, and alicyclic dicarboxylic acid components are particularly preferable.
Specifically, 1,2-cyclohexanedicarboxylic acid anhydride, 3-methyl-1,2-cyclohexanedicarboxylic acid anhydride, 4-methyl-1,2-cyclohexanedicarboxylic acid anhydride, norbornane-2,3-dicarboxylic acid Acid anhydride, 5-methylnorbornane-2,3-dicarboxylic acid anhydride, 1-cyclohexene-1,2-dicarboxylic acid anhydride, 3-methyl-1-cyclohexene-1,2-dicarboxylic acid anhydride, 4- Methyl-1-cyclohexene-1,2-dicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3-methyl-4-cyclohexene-1,2-dicarboxylic anhydride, 4-methyl-4 -Cyclohexene-1,2-dicarboxylic acid anhydride and the like are exemplified, in particular, 1,2-cyclohexanedicarboxylic acid anhydride, 3-methyl-1 2-cyclohexanedicarboxylic anhydride, 4-methyl-1,2-cyclohexanedicarboxylic anhydride is recommended.
These dicarboxylic acid components may be used alone or in combination of two or more.

  The above-mentioned “derivative of a dicarboxylic acid anhydride represented by the general formula (1)” refers to a dicarboxylic acid that is a hydrous acid of the acid anhydride, an acid chloride of the dicarboxylic acid, the dicarboxylic acid and 1 to 1 carbon atoms. 4 is a derivative such as an ester with a lower alcohol. These derivatives can also be used alone or in admixture of two.

<Alicyclic diamine component>
The diamine used in the alicyclic polyimide copolymer is an alicyclic diamine component represented by the general formula (2). R ¹ , R ² , R ³ and R ⁴ in the general formula (2) may be the same or different and are a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group, preferably a hydrogen atom or a methyl group. An ethyl group, more preferably a hydrogen atom or a methyl group is recommended. Y in the general formula (2) is a direct bond, —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —NH—, —C (—CH ₃ ) ₂ —, A divalent group selected from —C (—CF ₃ ) ₂ — or —C (═O) —, preferably a direct bond, —CH ₂ —, —O—, —C (—CH ₃ ) ₂ —; More preferably, —CH ₂ — is recommended.

Examples of the alicyclic diamine component include 4,4′-diamino-dicyclohexylmethane, 3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane, 3,3′-diethyl-4,4′-diamino- Dicyclohexylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diamino-dicyclohexylmethane, 3,3 ′, 5,5′-tetraethyl-4,4′-diamino-dicyclohexylmethane, 3, Specific examples include 5-diethyl-3 ′, 5′-dimethyl-4,4′-diaminodicyclohexylmethane.
These diamine components may be used alone or in combination of two or more.

  Among the above, 4,4′-diamino-dicyclohexylmethane, 3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diamino -Dicyclohexylmethane is preferred.

These alicyclic diamine components are not particularly limited in their production methods, and commercially available products or those obtained by a conventionally known production method can be used.
Conventionally known production methods include, for example, a method in which an aromatic diamine corresponding to a desired alicyclic diamine is subjected to catalytic hydrogenation using a ruthenium / alumina catalyst or the like, and the catalyst is filtered off, followed by (vacuum) distillation. Is exemplified. Since the distilled alicyclic diamine is colorless and transparent and does not contain colored impurities, it can be suitably used as a transparent polyimide raw material.

<Amount of preparation>
The charged molar ratio of each component (reaction substrate) according to the present invention is in the range of 97 to 105, preferably 99 to 103, and dicarboxylic acid for the alicyclic diamine component with respect to the tetracarboxylic acid component 100. Ingredients are in the range of 0.1-10, preferably in the range of 1-5. An alicyclic polyimide copolymer having a sufficient degree of polymerization can be obtained by an imidization reaction within these ranges, and the reaction can be stably performed without a sharp increase in viscosity during the reaction. it can. Further, the number of moles a of the tetracarboxylic acid component, the number of moles b of the dicarboxylic acid component, and the number of moles c of the alicyclic diamine component are preferably in a relationship of 2a + b ≦ 2c (this is a hydroxyl-free ( Alternatively, the total number of moles of a group of two carboxyl groups) and the number of moles of amino groups are equimolar or there is an excess of amino groups.

<Reaction solvent>
The reaction solvent used in the imidization reaction according to the present invention may be any reaction solvent as long as it does not inhibit the imidization reaction and can dissolve the produced alicyclic polyimide copolymer. For example, preferred examples include aprotic solvents, phenol solvents, ethers and glycol solvents.

Specific examples of the aprotic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea and the like. Amide solvents, lactone solvents such as γ-butyrolactone, γ-valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoric amide, hexamethylphosphine triamide, sulfur-containing dimethylsulfone, dimethylsulfoxide, sulfolane, etc. Solvents, ketone solvents such as acetone, cyclohexane and methylcyclohexane, amine solvents such as picoline and pyridine, ester solvents such as acetic acid (2-methoxy-1-methylethyl),
Specific examples of the phenol solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4 -Xylenol, 3,5-xylenol, etc.
Specific examples of ether and glycol solvents include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, and bis [2- (2-methoxyethoxy). Ethyl] ether, tetrahydrofuran, 1,4-dioxane and the like.
These reaction solvents may be used alone or in combination of two or more.

  Among these reaction solvents, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, and bis (2-methoxyethyl) ether are recommended.

  The amount of reaction solvent used may be an amount that can dissolve the polyimide copolymer to be produced. Specifically, it is preferably adjusted to 5 to 50% by weight, more preferably 10 to 40% by weight, and even more preferably 20 to 30% by weight with respect to the total amount of all reaction substrates and reaction solvents. It is recommended.

  The reaction solvent may be the same as or different from the organic solvent constituting the polyimide varnish, but is preferably the same in consideration of the complexity of the solvent replacement operation. When the reaction solvent is the same as the organic solvent of the polyimide varnish, the varnish concentration should be adjusted after the production of the alicyclic polyimide copolymer so that it can be easily molded (film / sheet molding, coating film formation, etc.) ( Viscosity adjustment) is preferred.

<Imidation reaction>
In general, as described above, the fully alicyclic polyimide resin generates a strong salt formed between amic acid and an alicyclic diamine, and the salt precipitates to significantly inhibit the progress of the reaction. In some cases, stirring is impossible due to pseudo-crosslinking. As a result, it was not easy to obtain a solvent-soluble fully alicyclic polyimide resin.
However, according to the present production method, the desired alicyclic polyimide copolymer can be produced by selecting the above reaction substrates and setting their use molar ratio within a specific range.

As a specific method related to the imidization reaction, (i) a predetermined amount of all reaction substrates and reaction solvents are charged into a reactor, stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then imidized. (Ii) A predetermined amount of a tetracarboxylic acid component, an alicyclic diamine, and a reaction solvent are charged into a reactor and stirred at room temperature to 80 ° C. for 0.5 to 30 hours. A method in which a dicarboxylic acid component is charged and an imidization reaction is performed at the reaction temperature of the imidization reaction, (iii) a predetermined amount of tetracarboxylic acid is charged after dissolving a predetermined amount of alicyclic diamine and reaction solvent in a reactor A method in which components are charged and stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then a dicarboxylic acid component is charged and an imidization reaction is performed at a reaction temperature of the imidization reaction,
(iv) A method in which a predetermined amount of all the reaction substrate and reaction solvent are charged into a reactor and immediately heated to the reaction temperature of the imidization reaction to carry out the imidization reaction. (v) The substrate concentration (or resin concentration) is 25. When the weight percentage is exceeded, the alicyclic diamine component 50 and the dicarboxylic acid component 0.1 to 10 are charged in a molar ratio to the tetracarboxylic acid component 100, stirred at room temperature for 1 to 2 hours, and then the reaction temperature 60 to Examples include a method (high concentration reaction method) in which the remaining amount of the alicyclic diamine component is charged (or dropped) at 120 ° C. and the temperature is raised to the reaction temperature of the imidization reaction after the completion of the charging, and the imidization reaction is performed. .

  The reaction temperature of the imidation reaction is usually 160 to 190 ° C, and preferably 170 to 180 ° C. When the reaction temperature is lower than 160 ° C., the imidization rate tends to be low. Moreover, when reaction temperature is higher than 190 degreeC, a thermal bridge | crosslinking body may be partially formed and it may become a cause of thickening and generation | occurrence | production of a gel-like substance.

  Although the reaction time of the imidation reaction depends on the substrate concentration (or resin concentration), it is usually about 2 to 10 hours after the start of distillation of the produced water. If the reaction time is too short, the imidization rate tends to be low. In addition, if the reaction time is too long, the reaction system may partially cause a thermal crosslinking reaction to thicken the reaction system or a gel-like product may be produced as a by-product, or the reaction system may be colored due to thermal degradation of the reaction solvent. is there.

In the imidation reaction, it is preferable to perform the reaction using a Dean-Stark apparatus or the like while removing water generated during imide ring closure from the reaction system. By performing such an operation, the degree of polymerization (and the imidization ratio) can be further increased. At this time, it is recommended to use a liquid or a gas body accompanied with water for the purpose of efficiently removing generated water. The accompanying liquid or gas body is generally called a reflux liquid, an azeotropic agent, an accompanying agent or an accompanying gas.
Examples of the reflux liquid include benzene, toluene, xylene, ethylbenzene, tetralin, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, and trimethylcyclohexane. These reflux solutions are usually used in an amount of 5 to 25% by weight based on the reaction solvent. The addition time is not particularly limited, and may be added to the reaction system from the time when the reaction solvent is charged, or may be added immediately before the imidization reaction.

  The inside of the reaction system is desirably an inert gas atmosphere from the viewpoint of preventing coloration and safety of the reaction system. Usually, after replacing the inside of the reaction system with an inert gas, a method of circulating an inert gas during the reaction is used. Examples of the inert gas include nitrogen and argon.

The imidation rate in the imidation reaction is preferably 100%, but the imidation rate effective from an industrial viewpoint is usually 60% or more, preferably 60 to 95%, more preferably 70 to 90%, In particular, 80 to 90% is recommended. This is because the operation of bringing the imidization rate close to 100% not only causes the reaction time of the imidization reaction to be exceeded (that is, the productivity is lowered), but also the reaction system is thickened due to the excess of the reaction time. And may promote the by-product of gel.
The imidation rate of less than 60% impairs the long-term stability of the polyimide varnish, and causes the generation of surface defects and voids as the generated water evaporates when the polyimide varnish is formed into a film-like molded product. In particular, this is not preferable because it may cause a decrease in transparency of the molded body.

  The intrinsic viscosity of the alicyclic polyimide copolymer is preferably 0.5 to 1.5 dL / g, more preferably 0.6 to 1.2 dL / g. When the intrinsic viscosity is less than 0.5 dL / g, a molded article such as a sheet or a film tends to be brittle, and is impractical. Moreover, when an intrinsic viscosity tends to exceed 1.5 dL / g, there exists a tendency for an alicyclic polyimide copolymer to become difficult to melt | dissolve in a reaction solvent (organic solvent).

  The intrinsic viscosity is an index of the degree of influence on the physical properties of the polyimide molded body and an important index in the production of the alicyclic polyimide copolymer. This production index means that the progress of the imidization reaction can be determined by measuring the intrinsic viscosity. Then, by setting the end point of the imidization reaction to a desired intrinsic viscosity and evaluating the course change, a desired alicyclic polyimide copolymer can be obtained efficiently or with good reproducibility.

  The glass transition temperature of the alicyclic polyimide copolymer is preferably 280 ° C or higher, more preferably 290 ° C or higher. The glass transition temperature of the polyimide copolymer tends to be further increased by molding as described below.

<Polyimide varnish>
The polyimide varnish of the present invention contains the above polyimide copolymer and an organic solvent.

  The polyimide varnish is prepared by (i) a method in which the reaction solvent solution of the obtained alicyclic polyimide copolymer is used as it is as a polyimide varnish, and (ii) a reaction solvent solution of the obtained alicyclic polyimide copolymer from the reaction solvent solution. Examples thereof include a method of obtaining a polyimide varnish by isolating a cyclic polyimide copolymer and then dissolving the isolated alicyclic polyimide copolymer in a desired organic solvent.

The solution viscosity of the polyimide varnish is usually preferably 0.5 to 20 Pa · s (measurement conditions; resin concentration 20% by weight, 25 ° C.). The viscosity is preferably adjusted as appropriate depending on the method of forming the varnish, the intended use of the polyimide molded body, and the like.
The resin concentration of the polyimide varnish can be determined by measuring the weight decrease before and after heating using a TG-DTA device (differential thermothermal weight simultaneous measurement device) as in the examples described later.

  The organic solvent is not particularly limited as long as it can dissolve the alicyclic polyimide copolymer, and can be selected according to the purpose and application. Specific examples include the same type as the reaction solvent.

<Other ingredients>
The alicyclic polyimide copolymer of the present invention uses “other aromatic and / or alicyclic tetracarboxylic dianhydride” as a part of the tetracarboxylic acid component as long as the desired physical properties are not impaired. be able to.

Other aromatic tetracarboxylic dianhydrides include tetracarboxylic dianhydrides having 10 to 30 carbon atoms and containing at least one aromatic ring in the molecule.
Specifically, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic acid dianhydride Anhydride, pyromellitic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′ , 3,3′-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane anhydride, 1,2-bis (2,3-dicarboxyphenyl) ethane anhydride, 1,1-bis (3,4-dicarboxyphenyl) Ethani anhydride, 1,2- (3,4-dicarboxyphenyl) ethane anhydride, bis (2,3-dicarboxyphenyl) methane anhydride, bis (3,4-dicarboxyphenyl) methane anhydride, 4,4 '-(p- Phenylenedioxy) diphthalic dianhydride, 4,4 '-(m-phenylenedioxy) diphthalic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5 8-Naphthalenetetracarboxylic dianhydride, 1,2-ethylenebis (anhydrotrimellitate), 1,4-phenylenebis (anhydrotrimellitate), 1,3,3a, 4,5,9b- Examples include hexahydro-5 (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1.3-dione. These aromatic tetracarboxylic dianhydrides can be used alone or in combination of two or more for the imidization reaction.
Moreover, as another alicyclic tetracarboxylic dianhydride, C8-C30 tetracarboxylic dianhydride which has at least 1 alicyclic structure in a molecule | numerator is mentioned. The alicyclic structure may be a monocyclic structure, a polycyclic structure, or a condensed ring structure.
Specific examples of the alicyclic tetracarboxylic acid include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, and 3-carboxymethyl. Cyclopentane-1,2,4-tricarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.1] heptanetetracarboxylic dianhydride, bicyclo [2 2.1] heptane-5-carboxymethyl-2,3,6-tricarboxylic acid dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid Anhydride, Bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, Pentacyclo [8.2.14, 7.02, 9.03,8] tetradecane- 5, 6, 11 12-tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, bicyclo [2.2.1] heptane-2 -Carboxymethyl-2,5,6-tricarboxylic acid dianhydride, bicyclo [2.2.2] octane-2-carboxyethyl-2,5,6-tricarboxylic acid dianhydride, 3,3 ', 4 Examples include 4'-dicyclohexyltetracarboxylic dianhydride. These alicyclic tetracarboxylic dianhydrides may be used alone or in combination of two or more for the imidization reaction.

  When other aromatic and / or alicyclic tetracarboxylic dianhydrides are used, the amount used is preferably 5 mol% or less, more preferably 3 mol, based on the total number of moles of the tetracarboxylic acid component. % Or less, particularly 1 mol% or less is recommended.

  In the alicyclic polyimide copolymer of the present invention, “other diamine component” may be used as a part of the alicyclic diamine component represented by the general formula (2) as long as desired physical properties are not impaired. it can. As another diamine component, any diamine component of aromatic diamine, aliphatic diamine, and alicyclic diamine may be used.

Examples of other aromatic diamines include C6-C30 diamines having at least one aromatic ring in the molecule.
Specifically, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 1, 1-bis (4-aminophenyl) ethane, 1,2-bis (4-aminophenyl) ethane, 2,2-bis (4-aminophenyl) propane, bis (4-aminophenyl) sulfide, bis (4- Aminophenyl) sulfoxide, bis (4-aminophenyl) sulfone, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 1,3- Bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) ben 1,4-bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, bis [4- (4-amino Phenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [3- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [3- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2- Bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) -3-methylphenyl] propane, 4,4′-bis (4-aminophenoxy) Phenyl,
4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) -3,3′-methylbiphenyl, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [3- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) ) Phenyl] sulfone,
Bis [3- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-amino Illustrative examples include phenoxy) phenyl] ketone and bis [3- (4-aminophenoxy) phenyl] ketone. These aromatic diamines can be used alone or in combination of two or more for the imidization reaction.
Examples of other alicyclic and aliphatic diamines include 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 2, 2-bis (4,4′-diaminocyclohexyl) propane, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, 2,3-diaminobicyclo [2.2.1] heptane, 2,5 -Diaminobicyclo [2.2.1] heptane, 2,6-diaminobicyclo [2.2.1] heptane, 2,7-diaminobicyclo [2.2.1] heptane, 2,5-bis (aminomethyl ) -Bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,3-bis (aminomethyl) -bi Cyclo [2.2.1] heptane, 3 (4), 8 (9) -bis (aminomethyl) -tricyclo [5.2.1.02.6] decane ethylenediamine, 1,3-propanediamine, 1, 4-butanediamine, 1,5-heptanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12 Examples include alkylene diamines such as -dodecane diamine, and polyoxyalkylene diamines such as oxydi (2-aminoethane), oxydi (2-aminopropane), and 2- (2-aminoethoxy) ethoxyaminoethane. These alicyclic and aliphatic diamines can be used alone or in combination of two or more for the imidation reaction.

  When other diamine components are used, the amount used is preferably 40 mol% or less, more preferably 20 mol% or less, and particularly preferably 10 mol% or less, based on the total number of moles of the diamine component.

<Method for producing alicyclic polyimide copolymer>
The manufacturing method of the alicyclic polyimide copolymer of this invention can be demonstrated similarly to description concerning the above-mentioned "alicyclic polyimide copolymer of this invention."
According to the method for producing an alicyclic polyimide copolymer of the present invention, since there is almost no precipitation of a salt of amic acid and an alicyclic diamine, a rapid change in viscosity (viscosity increase) of the reaction system can be suppressed. Thus, an imidization reaction can be performed, and a solvent-soluble all-alicyclic alicyclic polyimide copolymer having a high degree of polymerization can be efficiently obtained. This is considered that the dicarboxylic acid component is mainly involved.

In the imidization reaction according to the present invention, a known catalyst can be used. However, it is best to carry out the reaction without a catalyst from the viewpoint of complicated post-treatment, storage stability of the polyimide varnish (coloring and the like), and restrictions on the use of the polyimide molded body.
When a catalyst is used, for example, pyridine, quinoline, isoquinoline, α-picoline, β-picoline, piperidine, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, Organic bases such as tributylamine, imidazole, N, N-dimethylaniline, N, N-diethylaniline, inorganic bases represented by potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate Is mentioned. Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. It is done. Furthermore, lactones such as γ-butyrolactone and γ-valerolactone may be used.

<Polyimide molded product>
The polyimide molded body of the present invention can be obtained in a desired form such as a film shape, a film shape, or a sheet shape by a conventionally known molding method.
As a molding method, for example, (i) a polyimide varnish having a relatively low resin concentration is applied to a support (application process), dried and cured (drying / curing process), and then a polyimide molded body is formed from the support. A method of obtaining a film-like polyimide molded body by peeling (peeling step), (ii) a sheet-like polyimide molded body by molding a polyimide varnish having a relatively high resin concentration in the procedure of (i) And (iii) a method in which a polyimide varnish having a low resin concentration is applied to a material to be coated by spin coating or the like, and then dried and cured to obtain a film-like polyimide molded body.

As the support, a metal substrate such as a glass substrate, stainless steel, alumina, copper, or nickel is usually used.
When continuous coating is performed, a resin substrate is used. Examples of the resin substrate include polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylenesulfone, and polyphenylenesulfide.

Examples of the coating method on the support include spray coating, spin coating, and dip coating.
In order to obtain a film thickness suitable for a flexible display substrate (usually 0.1 to 500 μm, preferably 50 to 300 μm), a casting method is used.
The casting method may be cast with a glass rod having gaps formed at both ends with a tape seal or the like, or various coaters may be used. Examples of the coater include a bar coater, a knife coater, an air knife coater, a die coater, and a roll coater. The transfer rate of the support when using the coater is usually 0.1 to 5 m / s.

  The applied polyimide varnish may be used as it is at room temperature, may be heated to about 30 to 80 ° C. in order to reduce the solution viscosity, or an organic solvent for polyimide varnish may be added. Alternatively, the solution viscosity may be readjusted by adding a cellosolve organic solvent such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, or ethylene glycol monobutyl ether.

The drying / curing step is a step of volatilizing the organic solvent from the polyimide varnish and simultaneously completing imidization (making the imidization rate close to 100%).
As a drying method, in a batch production of polyimide molded bodies, a method of vacuum drying at a desired drying temperature (decompression degree: usually 1 to 10 mmHg) is recommended.
Moreover, in the continuous production of a polyimide molded body, a method of drying using a warm air heater, an IR heater or the like under normal pressure conditions is exemplified. In the case of drying at normal pressure, it is preferably performed in an inert gas atmosphere in order to suppress yellowing of the molded body. Examples of the inert gas include nitrogen and argon.
It is recommended that the drying temperature be adjusted so that the surface temperature of the molded body is 100 ° C to 500 ° C, preferably 180 ° C to 400 ° C, more preferably 200 ° C to 350 ° C. When the drying temperature is low, the imidation rate is low, and the organic solvent solvated with amic acid remains in the molded product, so that the glass transition temperature of the polyimide molded product tends to decrease. On the other hand, when the drying temperature is too high, yellowing of the molded body tends to occur and the transparency tends to be impaired.

  The step of peeling the polyimide molded body from the support may be performed after drying and curing are complete. If the support does not have sufficient heat resistance, the alicyclic polyimide copolymer is used as a self-supporting film. After drying to the extent that it has sufficient strength, it may be peeled off from the support and then dried and cured. Usually, the solvent content in the polyimide molded body has strength as a self-supporting film from about 20 to 25% by weight.

The peeled polyimide molded body may be an unstretched molded body that does not give anisotropy, or may be a uniaxially stretched or biaxially stretched molded body, depending on the purpose and application.
When a polyimide molded body is used for applications in which colorless transparency is important, an unstretched molded body is preferable.
When biaxial stretching is performed, it is usually called a tenter, and the film end is stretched by a fixed clip with an apparatus. The temperature condition for biaxial stretching is performed near the glass transition temperature of the film.

The imidation ratio of the polyimide molded body is preferably 80% or more, more preferably 90% or more. The imidization rate is a value obtained by the method described in Examples described later in the present specification and claims.
Although the polyimide molded body having a low imidization rate depends on the intended use, when exposed to high-temperature processing conditions, the imidization reaction may re-progress to cause defects on the substrate surface and may impair dimensional stability. .

  The glass transition temperature of the polyimide molded body is one of heat resistance indicators, and the glass transition temperature is preferably 290 ° C. or higher, more preferably 300 ° C. or higher. The glass transition temperature is a value obtained by the method described in Examples described later in the present specification and claims.

  The total light transmittance (film thickness: 100 μm) of the polyimide molded body is usually 85% or more, preferably 90% or more. The total light transmittance is a value obtained by the method described in Examples described later in this specification and claims. This range is an effective range particularly in applications that place importance on colorless transparency such as a display substrate.

  The yellowness of the polyimide molded body is usually 10 or less, preferably 4 or less. The yellowness is a value obtained by the method described in Examples described later in the present specification and claims. This range is an effective range particularly in applications that place importance on colorless transparency such as a display substrate.

  The toughness of the polyimide molded body can be evaluated by “breaking elongation” and “breaking strength” by a tensile test. The elongation at break is preferably 5% or more, more preferably 10% or more. The breaking strength is preferably 60 MPa or more, more preferably 80 MPa or more. The elongation at break and the strength at break are values obtained by the methods described in the examples described later in the present specification and claims.

<Plastic substrate>
The plastic substrate of the present invention is characterized by comprising the polyimide molded body. The manufacturing method can be obtained from a conventionally known manufacturing method, for example, the above-mentioned forming method.

The plastic substrate is suitable as a flexible display substrate because it has the heat resistance, transparency and toughness of the polyimide molded body. Examples of the flexible display include a liquid crystal display, an organic electroluminescence display, a field emission display, and various electronic papers such as an electrophoretic type, a twist ball type, an electronic powder fluid type, and a magnetophoretic type.
These displays include color images, moving images, and other sophisticated functions.

An electrode such as ITO (Indium Tin Oxide) is usually formed on the flexible display substrate. Efforts are being made to reduce the electrical resistance of ITO in order to obtain higher definition images. For this reason, electrode deposition at a high temperature is required, and the processing temperature is 200 to 250 ° C. The flexible display substrate needs to have heat resistance that can withstand this process.
Since the plastic substrate (polyimide molded product) of the present invention exhibits a high glass transition temperature (exceeds 250 ° C.), it has sufficient heat resistance as a flexible display substrate.

  The plastic substrate is preferably used as a plastic substrate used in the field of electrical and electronic components, such as for liquid crystal displays, organic electroluminescence displays, electronic paper, solar cells, and electrical insulating films of electronic devices. it can. In addition to the plastic substrate (for example, flexible display substrate), a glass substrate substitute plastic such as a solar cell protective film, a color filter protective film, a transparent conductive film substrate, a TFT substrate, an optical disk substrate, an electrical insulating film of an electronic device, an optical fiber, It can also be used as an optical material for lenses, touch panels and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In addition, the analytical value in each Example and a comparative example was calculated | required with the following method.

[Evaluation of Alicyclic Polyimide Copolymer and Polyimide Varnish]
(I) Intrinsic viscosity The intrinsic viscosity (dL / g) of the alicyclic polyimide copolymer according to the present invention was determined according to the following method.
Using the measurement result of the resin concentration in (ii) below, an intrinsic viscosity measurement solution was prepared by diluting with an organic solvent used in the varnish so that the resin concentration of the polyimide varnish was 0.5 g / dL. . Next, the drop time of the solution and the drop time of the organic solvent were determined using an Ostwald viscometer. Using the obtained dropping time, the intrinsic viscosity (dL / g) of the alicyclic polyimide copolymer was calculated according to the following calculation formula (1).
(a formula)
Intrinsic viscosity (dL / g) = [ln (T ₁ / T ₀ )] / 0.5 (1)
T ₁ : Dropping time of solution for measuring intrinsic viscosity (seconds)
T ₀ : organic solvent falling time (seconds)

(Ii) Resin concentration of polyimide varnish The resin concentration (% by weight) of the polyimide varnish according to the present invention was determined according to the following method.
10 mg of polyimide varnish was precisely weighed and set in a TG-DTA apparatus (EXSTAR 6000, TG-DTA 6200 manufactured by Seiko Instruments Inc.), and the weight at 400 ° C. was measured under the following measurement conditions. Using the obtained measured value, the resin concentration (% by weight) of the polyimide varnish was calculated according to the following calculation formula (2).
Measurement condition;
Temperature rising rate: 5 ° C / min Flowing nitrogen amount: 100ml / min Measurement start temperature: 25 ° C
(a formula)
Resin concentration (% by weight) = (W ₁ / W ₀ ) × 100 (2)
W ₁ : Weight of measurement sample at 400 ° C. (g)
W ₀ : Weight of measurement sample before measurement (g)

(Iii) Storage stability of polyimide varnish
The storage stability of the polyimide varnish according to the present invention was evaluated according to the following method.
The polyimide varnish was placed in a sealable sample bottle, which was then sealed with nitrogen and stored at room temperature for 4 months. It evaluated by comparing the intrinsic viscosity before and after evaluation of storage stability.
<Criteria>
A: Change in intrinsic viscosity is 5% or less.
○: Change amount of intrinsic viscosity is 10% or less.
Δ: Change amount of intrinsic viscosity is 20% or less.
X: Change amount of intrinsic viscosity is larger than 20%.

[Imidation rate]
The imidization rate (%) was determined according to the following method.
The absorbances of the polyimide molded body (film form) and the polyimide preparation at 1350 cm ⁻¹ and 1470 cm ⁻¹ were measured by ATR method (total diffuse reflection method) using FT-IR Spectrum One (manufactured by PerkinElmer). Using the obtained absorbance, calculation was performed according to the following calculation formula (3) to determine the imidization ratio (%) of the molded article.
(a formula)
Imidation ratio (%) = [(A ¹ / B ¹ ) / (A ⁰ / B ⁰ )] X100 (3)
A ¹ : Absorbance of polyimide molded body at 1470 cm ⁻¹ B ¹ : Absorbance of polyimide molded body at 1350 cm ⁻¹ A ⁰ : Absorbance of polyimide standard at 1470 cm ⁻¹ B ⁰ : Absorbance of polyimide standard at 1350 cm ⁻¹ The polyimide The standard is one having an imidization rate of 100%, and is prepared by heat-treating a polyimide molded body to be measured at a surface temperature of 360 ° C. for 1 hour under vacuum.
Incidentally, infrared ray absorption of 1350 cm ^-1 indicates the characteristic absorption of an imide ring, the infrared absorption of 1470 cm ^-1 represents the characteristic absorption of the alicyclic compound.

[Heat resistance evaluation]
(I) Glass transition temperature The glass transition temperature (° C) of the polyimide molded body (alicyclic polyimide copolymer) according to the present invention was determined according to the following method.
Using a dynamic viscoelasticity measuring device RHEOGEL-E4000 (manufactured by UPM), tan δ of the polyimide molded body was measured under the following measurement conditions. The maximum value of tan δ was defined as the glass transition temperature (° C.).
Measurement condition;
Measurement mode: Tensile mode Sine wave: 10 Hz
Temperature increase rate: 5 ° C / min

[Transparency evaluation]
(I) Total light transmittance The total light transmittance (%) of the polyimide molded body (alicyclic polyimide copolymer) according to the present invention is determined by using a haze meter HAZE GARD II (manufactured by Toyo Seiki Co., Ltd.). It measured according to 7361-1.

(Ii) Yellow index (yellowness)
The yellow index of the polyimide molded body (alicyclic polyimide copolymer) according to the present invention was measured according to JIS K7105 using a colorimeter CM-3500d (manufactured by Minolta) and using a light source C.

[Mechanical properties evaluation]
(I) Elongation at break and strength at break (toughness evaluation)
The “breaking elongation” and “breaking strength” of the polyimide molded body (alicyclic polyimide copolymer) according to the present invention are measured according to JIS K-7127 using a universal material testing machine 5565 (manufactured by Instron). did.
Under the conditions of 25 ° C. and RH 60%, a test piece having a thickness of 80 μm and a width of 10 mm was fixed to the tester so that the length was 50 mm, and then tensile measurement was performed at a speed of 10 mm / min.

Example 1
After substituting the inside of a 2 L four-necked flask equipped with a thermometer, a stirrer, a nitrogen introducing tube, a separator decanter, and a cooling tube with nitrogen, 4,4′-diaminodicyclohexyl was used as an alicyclic diamine component under a nitrogen stream. Methane (hereinafter referred to as “HDAM”) 122.60 g (0.5827 mol) and 1,17-dimethylimidazolidinone (hereinafter referred to as “DMI”) 1017 g as a reaction solvent were charged and stirred at room temperature for 15 minutes. The diamine was dissolved. Next, after heating up to 50 ° C., 128.69 g (0.5741 mol) of powdered 1,2,4,5-cyclohexanetetracarboxylic dianhydride (hereinafter referred to as “HPMDA”) as a tetracarboxylic acid component. ) Was added. After completion of the addition, the temperature was raised to 80 ° C. and stirred for 15 minutes. At this time, a small amount of salt precipitated. Next, after adding 2.90 g (0.0172 mol) of 4-methyl-1,2-cyclohexanedicarboxylic anhydride (hereinafter referred to as “MH”) as a dicarboxylic acid component, the temperature was raised to 120 ° C., Stir for 15 minutes. At this time, the salt was completely dissolved.
Next, after adding 179 g of xylene as a reflux liquid, the temperature was raised to 180 ° C., and an imidization reaction was performed at the reaction temperature for 3 hours. Along with this reaction, the produced water azeotroped with xylene, so the distilled water was separated with a liquid separation decanter. Distilled water was 19.1 g.
After completion of the reaction, stirring was continued at 180 ° C. for 0.5 hours to distill off xylene, thereby obtaining a DMI solution (present polyimide varnish) of the alicyclic polyimide copolymer of the present invention. Table 1 shows the intrinsic viscosity of the obtained alicyclic polyimide copolymer and the evaluation results relating to the polyimide varnish.

(Example 2)
The inside of a 0.2 L four-necked flask equipped with a thermometer, a stirrer, a nitrogen introducing tube, a separator decanter, and a cooling tube was purged with nitrogen, and then 3,3′- as an alicyclic diamine component under a nitrogen stream 12.32 g (0.05167 mol) of dimethyl-4,4′-diamino-dicyclohexylmethane (hereinafter referred to as “2MeHDAM”), N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”) 96 as a reaction solvent. .6 g was charged and stirred at room temperature for 15 minutes to dissolve the diamine. Subsequently, after heating up to 50 degreeC, powdery HPMDA 11.35g (0.05064 mol) was added as a tetracarboxylic-acid component. After completion of the addition, the temperature was raised to 80 ° C. and stirred for 15 minutes. At this time, a small amount of salt precipitated. Next, after adding 0.348 g (0.00207 mol) of MH, it heated up to 120 degreeC and stirred for 15 minutes. At this time, the salt was completely dissolved.
Next, after 19.8 g of xylene was added as a reflux liquid, the temperature was raised to 180 ° C., and an imidization reaction was performed at that reaction temperature for 4 hours. Along with this reaction, the produced water azeotroped with xylene, so the distilled water was separated with a liquid separation decanter. Distilled water was 1.9 g.
After completion of the reaction, stirring was continued at 180 ° C. for 0.5 hours to distill off xylene, and an NMP solution (present polyimide varnish) of the alicyclic polyimide copolymer of the present invention was obtained. Table 1 shows the intrinsic viscosity of the obtained alicyclic polyimide copolymer and the evaluation results relating to the polyimide varnish.

(Example 3)
In place of 2MeHDAM, 13.77 g (0.0517 mol) of 3,3 ′, 5,5′-tetramethyl-4,4′-diamino-dicyclohexylmethane (hereinafter referred to as “4MeHDAM”) was used. It carried out similarly to Example 2 and obtained the NMP solution (this polyimide varnish) of the polyimide of this invention. Table 1 shows the intrinsic viscosity of the obtained alicyclic polyimide copolymer and the evaluation results relating to the polyimide varnish.

(Comparative Example 1)
After replacing the inside of a 2 L four-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, separator decanter, and cooling tube with nitrogen, 11.2 g (0.05 mol) of HPMDA and 40.0 g of NMP were charged under a nitrogen stream. HPMDA was dissolved. Next, a solution obtained by dissolving 10.5 g (0.05 mol) of HDAM in 45.0 g of N, N-dimethylacetamide was reacted at room temperature while dropping over 2 hours from the dropping funnel. At this time, a large amount of salt having a large particle size was generated, making stirring difficult.
Next, 30.0 g of xylene was added as a refluxing liquid, the temperature was raised to 170 ° C. to completely dissolve the salt, and then the reaction was performed for 3 hours while separating water azeotroped with xylene with a separating decanter. went. Distilled water was 3.3 g. Furthermore, after completion | finish of reaction, stirring was continued at 190 degreeC for 0.5 h, xylene was distilled off, and the NMP solution (polyimide varnish outside this invention) of the polyimide resin outside this invention was obtained. Table 1 shows the intrinsic viscosity of the obtained alicyclic polyimide copolymer outside the present invention and the evaluation results relating to the polyimide varnish outside the present invention.

(Comparative Example 2)
The same procedure as in Comparative Example 1 was conducted except that 45.0 g of N, N-dimethylacetamide was replaced with 45.0 g of NMP. A small amount of salt precipitated at the beginning of the reaction, but dissolved when the temperature was raised to 120 ° C. Furthermore, the temperature was raised to 170 ° C., and after 1 hour, the viscosity rapidly increased and stirring was impossible, and the reaction was stopped. A portion was collected from the reaction product, and the intrinsic viscosity and resin concentration were measured. The results are shown in Table 1.

(Comparative Example 3)
After replacing the inside of a 2 L four-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, separator decanter, and cooling tube with nitrogen, 11.2 g (0.05 mol) of HPMDA and 40.0 g of NMP were charged under a nitrogen stream. HPMDA was dissolved. Next, a solution obtained by dissolving 10.5 g (0.05 mol) of HDAM in 45.0 g of N, N-dimethylacetamide was reacted at room temperature while dropping over 2 hours from the dropping funnel. Furthermore, stirring was continued at room temperature for 2 hours to obtain a polyamic acid varnish. The intrinsic viscosity of the obtained polyamic acid was listed in the column of alicyclic polyimide copolymer in Table 1, and the evaluation results relating to the obtained polyamic acid varnish were listed in the column of polyimide varnish in Table 1, respectively.

  From Table 1, it can be seen that the alicyclic polyimide copolymer of the present invention is excellent in solvent solubility and storage stability. Moreover, since intrinsic viscosity is high, it turns out that it has a high polymerization degree which can give polyimide molded objects, such as a film.

(Examples 4 to 6) and (Comparative Examples 4 to 6)
The polyimide varnish of the present invention obtained in Examples 1 to 3, the polyimide varnish of the present invention obtained in Comparative Examples 1 and 2 and the polyamic acid varnish obtained in Comparative Example 3 were sealed with a tape seal of 700 μm. The produced glass rod was used to cast on a glass substrate. Subsequently, it deaerated in room temperature for 1 hour in a vacuum dryer, and also heated up to 310 degreeC in 2 hours, and heat-processed at that temperature for 1 hour. It cooled to room temperature and peeled the film from the board | substrate. Table 2 shows the evaluation results of the imidization rate, total light transmittance, yellowness and glass transition temperature, and toughness of each film (polyimide molded product) obtained.
In addition, since the polyimide varnish obtained in Comparative Example 2 could not be formed into a film, the physical properties could not be evaluated.

As can be seen from Table 2, the polyimide molded body (film form) obtained from the polyimide varnish of the present invention has high transparency, high heat resistance and high toughness. Further, since the molded article has the characteristics, it can be seen that the molded article is particularly useful as a plastic substrate such as a flexible display substrate.
And it turns out that the manufacturing method of this invention becomes control of the said imidation reaction very easily, and can obtain the alicyclic polyimide copolymer which has the said performance industrially.

The alicyclic polyimide copolymer of the present invention is a solvent-soluble type having heat resistance and transparency. A polyimide molded body (film or the like) obtained by molding a polyimide varnish obtained from the polyimide copolymer has high toughness in addition to the above characteristics, and can be suitably used for a flexible display substrate and the like.

Claims (10)

In the presence of a reaction solvent, at least one tetracarboxylic acid component selected from the group consisting of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and derivatives thereof and a dicarboxylic acid anhydride represented by the following general formula (1) At least one dicarboxylic acid component selected from the group consisting of a product and derivatives thereof and an alicyclic diamine component represented by the following general formula (2) with respect to the tetracarboxylic acid component 100: An alicyclic polyimide copolymer obtained by carrying out an imidization reaction by heating dehydration at a charging molar ratio in the range of 10 and alicyclic diamine components 97 to 105.
General formula (1)

[In formula, A represents a C2-C13 bivalent group. ]
General formula (2)

[Wherein, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group. Y is a direct bond, —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —NH—, —C (—CH ₃ ) ₂ —, —C (—CF ₃ ) Represents a divalent group selected from _2- or -C (= O)-. ] The alicyclic polyimide copolymer according to claim 1, wherein the alicyclic polyimide copolymer has an intrinsic viscosity of 0.5 to 1.5 dL / g.   A polyimide varnish containing the alicyclic polyimide copolymer according to claim 1 or 2 and an organic solvent.   A polyimide molded body obtained by molding the polyimide varnish according to claim 3.   The polyimide molded body according to claim 4, wherein the polyimide molded body is in the form of a film, a film, or a sheet.   The polyimide molded body according to claim 4 or 5, wherein the polyimide molded body has a glass transition temperature of 290 ° C or higher and an imidization ratio of 80% or higher.   The plastic substrate which consists of a polyimide molded body in any one of Claims 4-6.   An electrical / electronic component comprising the plastic substrate according to claim 7.   The electrical / electronic component according to claim 8, wherein the electrical / electronic component is a liquid crystal display, an organic electroluminescence display, electronic paper, a solar cell, or an electrical insulating film. In the presence of a reaction solvent, at least one tetracarboxylic acid component selected from the group consisting of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and derivatives thereof and a dicarboxylic acid anhydride represented by the general formula (1) And at least one dicarboxylic acid component selected from the group consisting of derivatives thereof, and an alicyclic diamine component represented by the general formula (2), with respect to the tetracarboxylic acid component 100, the dicarboxylic acid component 0.1 to 10 and A method for producing an alicyclic polyimide copolymer, wherein the imidization reaction is carried out by heat dehydration at a charged molar ratio of the alicyclic diamine components 97 to 105.
General formula (1)

[In formula, A represents a C2-C13 bivalent group. ]

[Wherein, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group or an ethoxy group. Y is a direct bond, —CH ₂ —, —O—, —S—, —SO ₂ —, —C (═O) —NH—, —C (—CH ₃ ) ₂ —, —C (—CF ₃ ) Represents a divalent group selected from _2- or -C (= O)-. ]