JP2006306990A - Ester imide oligomer, thermally cured product thereof and method for producing the oligomer and the product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new ester imide oligomer having excellent processibility such as solubility in an organic solvent and thermoplasticity, to provide thermally cured products thereof having both of sufficient tenacity and a high glass transition temperature, and to provide methods for producing the oligomer and the cured products. <P>SOLUTION: The ester imide oligomer has a recurring unit represented by formula (2) (wherein, A is a divalent aromatic or aliphatic group) and the terminals thereof are sealed with a thermally crosslinkable group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel esterimide oligomer having excellent processability, that is, organic solvent solubility and thermoplasticity, a thermoset product having high toughness and a high glass transition temperature, and a method for producing these.

  Polyimide has not only excellent heat resistance but also chemical resistance, radiation resistance, electrical insulation, excellent mechanical properties, etc., so it can be used for flexible printed circuit boards, tape automation bonding substrates, and semiconductors. Currently, it is widely used in various electronic devices such as protective films for elements and interlayer insulating films for integrated circuits.

  Generally, polyimide has a high degree of polymerization obtained by equimolar reaction of an aromatic tetracarboxylic dianhydride such as pyromellitic anhydride and an aromatic diamine such as diaminodiphenyl ether in an aprotic polar organic solvent such as dimethylacetamide. The polyimide precursor is formed into a film and cured by heating.

  However, in order to maintain the heat resistance of polyimide, the skeleton structure must be rigid in terms of molecular design. As a result, polyimide is almost insoluble in organic solvents and does not melt above the glass transition temperature, so the polyimide itself is molded. Processing is usually not easy.

  Therefore, generally, a method is used that uses a polyimide precursor that exhibits high solubility in an amide organic solvent. Specifically, a polyimide film is formed by applying an aprotic organic solvent solution of a polyimide precursor onto a metal substrate and drying, followed by heating at a high temperature of 250 ° C. to 350 ° C. to cause dehydration ring closure (imidation) reaction. .

  However, since the imidization reaction temperature is very high as described above, the film forming process may not be applied in some fields. For example, the heat resistance temperature of a color filter, which is indispensable for colorization of liquid crystal displays, is about 200 ° C. Even if an attempt is made to form a polyimide film for a liquid crystal alignment film via imidization of a polyimide precursor, at this temperature the imide of the coating film The chemical reaction cannot be completed.

  In the above fields, polyimides soluble in organic solvents are applied. In this case, after applying a solution (varnish) in which polyimide is dissolved in an organic solvent to the substrate, it is only necessary to volatilize the solvent. Therefore, it is possible to form a film at a temperature much lower than the imidization temperature. For example, even when N-methyl-2-pyrrolidone having a high boiling point and hardly volatilizes is used as a solvent, a treatment at 150 ° C. to 200 ° C. is sufficient.

  In a normal polyimide film forming process via a precursor, the problem of thermal stress generated in a laminate of a metal substrate and a polyimide film is serious. Although the thermal stress is in a relaxed state during the imidization reaction at high temperature, thermal stress is generated in the process of cooling the laminate from the imidization temperature to room temperature, and a line between the metal substrate and the polyimide film is generated. It increases as the difference in thermal expansion coefficient increases and the imidization temperature increases.

  One way to reduce thermal stress is to reduce the thermal expansion of polyimide. Most polyimides typically have a linear thermal expansion coefficient in the range of 50-100 ppm / K, which is much larger than the linear thermal expansion coefficient of 17 ppm / K for metal substrates such as copper, so it is close to the value of copper, approximately 20 ppm / K or less. Research and development of low thermal expansion polyimides exhibiting

  Another measure is to lower the heat treatment temperature. One is an attempt to disperse an imidation catalyst in a polyimide precursor film to lower the imidization reaction temperature itself, and the other is a method using soluble polyimide.

  As the imidization catalyst in the former low-temperature curing type polyimide system, 3-hydroxybenzoic acid, 4-hydroxyphenylacetic acid and the like are effective for greatly lowering the imidization temperature, and pyromellitic anhydride and 4,4′- It is known that the imidization reaction is almost completed at about 180 ° C. even in a polyimide precursor system composed of diaminodiphenyl ether (see, for example, Non-Patent Document 1).

  However, in this technique, since it is necessary to add a large amount of imidization catalyst (2 times moles with respect to repeating units) in the polyimide precursor film, there arises a problem of film purity and film reduction. Furthermore, when the polyimide film obtained by low-temperature curing (imidization) is placed in an environment at or above its curing temperature, there is a risk of thermal deformation and significant dimensional changes.

  On the other hand, the latter organic solvent-soluble polyimide does not require a very high temperature treatment for film formation as described above, so even if the coefficient of linear thermal expansion of the film is not so low, the film is cooled from the film formation temperature to room temperature. The amount of contraction of the film does not become so large, and the residual stress can be suppressed to some extent.

  In the film-forming process in which the polyimide precursor solution is applied and imidized on a substrate such as copper, there is a problem that copper migrates into the polyimide precursor film and electrical characteristics deteriorate. In order to prevent this, the surface treatment of the copper substrate must be performed. On the other hand, in the soluble polyimide, there is no concern about copper migration, so that no extra steps such as copper surface treatment are required.

  Moreover, in the polyimide film preparation method via a precursor, since a desorbing component accompanying an imidization reaction is generated, it is difficult to prepare a thick film having a film thickness exceeding about 100 μm. On the other hand, since a film forming process using soluble polyimide does not involve an imidization reaction, a polyimide sheet having a thickness exceeding 1 mm can be produced by performing multi-step coating.

  Polyimide is used for a flexible printed circuit board (FPC), but the use of a backing material using a composite material such as glass / epoxy is indispensable for a portion requiring mechanical strength. This is because the thickness of the polyimide film used for FPC is limited in the manufacturing process. If a thick polyimide sheet can be produced using soluble polyimide as described above, the backing process can be omitted and, as a result, the FPC can be miniaturized.

  However, if an attempt is made to impart solubility to the organic solvent in the polyimide, introduction of a bent bond into the main chain or introduction of a bulky substituent as a side chain generally results in a significant decrease in the glass transition temperature. Therefore, it is not easy in terms of molecular design to obtain a practically useful polyimide having a glass transition temperature of 250 ° C. or higher and being dissolved at a high concentration in an aprotic organic solvent such as N-methyl-2-pyrrolidone.

  For example, when a diamine containing a flex bond and an alkyl substituent is used as a monomer, a polyimide soluble in an organic solvent may be obtained. However, when polymerization is carried out using such a diamine, the polymerization reactivity is remarkably lowered due to the steric hindrance of the substituent, and a polyimide precursor having a sufficiently high degree of polymerization is often not obtained, and there is a problem in the toughness of the polyimide film. Arise. Moreover, there exists a possibility that thermal oxidation stability may fall by presence of an alkyl substituent.

  In addition, it is known that introduction of a trifluoromethyl substituent weakens the intermolecular force of polyimide and greatly contributes to improvement in solubility. For example, when 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride is used as tetracarboxylic dianhydride, a polyimide precursor having a high degree of polymerization can be obtained without steric hindrance during the polymerization reaction. However, the use of fluorinated monomers is disadvantageous in terms of production costs.

  By adjusting the degree of polymerization of the polyimide by using a terminal blocker during the polymerization of the polyimide precursor, the solubility and thermoplasticity generally improve, but at the same time the glass transition temperature decreases and the film toughness decreases drastically. Accompanied by. Therefore, in the field where film toughness such as FPC is required, the approach of imparting processability by controlling the molecular weight is not so preferable.

  Thus, soluble polyimide has various advantages in the coating film forming process, but in addition to this, if the polyimide film also exhibits thermoplasticity, application to a wider field is expected. For example, the present invention can be applied to an adhesive for producing a polyimide / copper laminate (copper-clad board) or a circuit protective film in FPC.

  In recent years, with the increase in the density of electric circuit wiring in FPC, a high degree of dimensional stability of the polyimide film itself has been required. In such high-density wiring applications, a three-layered copper-clad board that has pasted a polyimide film with a copper foil via an acrylic or epoxy adhesive has been the mainstream. The two-layer type in which the precursor is applied and heat-cured (cast method), or a pseudo two-layer type copper-clad plate using a heat-resistant thermoplastic polyimide as an adhesive is being transferred.

  If there is a polyimide that simultaneously satisfies solubility, thermoplasticity, high glass transition temperature, and high toughness, a low thermal expansion polyimide film is formed on the copper foil by casting, and then a soluble polyimide solution is applied and dried. And it becomes possible to produce a double-sided copper clad board easily by thermocompression bonding this and copper foil.

  This can be produced in the same manner by previously forming a soluble polyimide film on a copper foil and pasting it on the polyimide surface of the copper / low thermal expansion polyimide film laminate. Here, the soluble polyimide is advantageous in that the coating thickness of the soluble polyimide solution, that is, the thickness of the adhesive layer can be easily controlled, like the conventional adhesive.

  However, in order to simultaneously exhibit organic solvent solubility and thermoplasticity, it is necessary to control the molecular weight in addition to the introduction of a bent structure and a substituent to the polymer skeleton, and the glass transition temperature may be greatly reduced. For example, ULTEM1000 (General Electric) is known as a polyimide that exhibits organic solvent solubility and thermoplasticity, but its glass point transition temperature is relatively low at 215 ° C., and there is a problem in heat resistance during the solder reflow process. This is not applicable to FPC applications.

  In order to achieve both high solubility in organic solvents, high thermoplasticity, and high glass transition temperature, the present inventors have focused on 2,2'-biphenylene bonds (see Japanese Patent Application No. 2004-115129). If the isomer 4,4'-biphenylene bond is introduced into the polyimide main chain, the skeleton becomes rigid and the glass transition is expected to increase greatly, but on the other hand, the polymer chains are closely packed. Since packing is easy, intermolecular interaction is strengthened, crystallinity is increased, and solubility is extremely lowered.

  On the other hand, in the 2,2'-biphenylene bond, since it is linked to the ortho position of biphenyl, the molecular planes of the biphenyl moiety are greatly twisted with each other due to steric hindrance, and the main chain skeleton is greatly bent. Thereby, it is expected that the intermolecular interaction is greatly weakened and the solubility is dramatically improved. In addition, this steric hindrance hinders internal rotation around the biphenyl bond, and is considered to maintain a high glass transition temperature.

  A monomer having a 2,2'-biphenylene bond can be easily synthesized from 2,2'-biphenol and trimellitic anhydride chloride, and the resulting monomer is also highly pure. Moreover, the raw materials to be used are available at low cost, which is advantageous in terms of the production cost of polyimide.

  A polyimide derived from an acid dianhydride containing 2,2'-biphenylene units via an ether linkage, ie 2,2'-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride has been published (For example, refer nonpatent literature 2). For example, a polyimide obtained from this acid dianhydride and 4,4'-diaminodiphenyl ether is soluble in N-methyl-2-pyrrolidone, but the glass transition temperature is not so high as 213 ° C. This is because the ether bond has a low internal rotation barrier.

  On the other hand, the polyimide according to the above-mentioned patent application by the present invention has a higher glass transition temperature because 2,2'-biphenylene units are introduced through an ester bond that is less likely to rotate internally.

  Furthermore, acid dianhydrides containing 2,2′-biphenylene units via an ester bond, ie 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride and 4,4′-diaminodiphenyl ether Has been reported (see, for example, Patent Document 1). However, in this patent document, by adopting a 2,2′-biphenylene structure, polyimide exhibits high solubility in an organic solvent, is thermoplastic, and has a high glass transition temperature and high toughness. There is no disclosure about how excellent properties in processing can be achieved.

  Polyesterimide derived from 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride and paraphenylenediamine is soluble in N-methyl-2-pyrrolidone and has a glass transition point of 243 ° C. It has been reported that it exhibits superior properties compared to existing soluble / thermoplastic polyimides (see, for example, Non-Patent Document 3).

  However, in order to apply the polyesterimide to the industrial field, it is further required to lower the thermal processing temperature, improve the melt flowability, and improve the glass transition temperature, but no practical material is known.

Industrial materials, Vol. 43, no. 6, (1995), p. 48 Recent Progress in Polyimide 1994, Imai, Enomoto, Raytec, 1994, p. 25 Polymer Society Proceedings, Vol. 53, 1629 (2004) US Pat. No. 3,355,427

  The present invention relates to a novel esterimide oligomer having excellent processability, ie, organic solvent solubility and thermoplasticity, sufficient toughness and a high glass transition temperature thereof, and its thermoset useful in practical use in the above industrial field, and these The manufacturing method of this is provided.

  In view of the above problems, as a result of intensive studies, it has been found that the ester polyimide oligomer represented by the formula (2) and its thermoset satisfy the above-mentioned required characteristics, and the present invention has been completed.

That is, the present invention is as follows.
1) Formula (1):

(Wherein A represents a divalent aromatic group or aliphatic group), and the terminal thereof is sealed with a thermally crosslinkable group, Esterimide oligomer precursor.
2) Formula (2):

(Wherein A represents a divalent aromatic group or aliphatic group), and the terminal thereof is sealed with a thermally crosslinkable group, Esterimide oligomer.
3) A thermoset obtained by subjecting the esterimide oligomer described in formula (2) to a thermal crosslinking reaction.
4) A method for producing an ester imide oligomer according to formula (2), wherein the ester imide oligomer precursor according to formula (1) is subjected to a dehydration cyclization reaction by heating or a dehydrating reagent.
5) A varnish containing the ester imide oligomer according to the formula (2).

  In the ester imide oligomer having the repeating unit represented by the formula (2) of the present invention and having its terminal end sealed with a thermally crosslinkable group, the same tetracarboxylic acid residue and diamine are used. Lower thermal processing temperature, improved melt flowability, and improved organic solvent solubility are achieved compared to the corresponding polyesterimides composed of residues, and the thermoset has improved toughness and glass transition temperature. Therefore, it is expected as a practical material for printed wiring boards.

  The present invention is described in detail below.

  First, an ester imide oligomer precursor and an ester imide oligomer, which have repeating units represented by formulas (1) and (2) and whose ends are sealed with a thermally crosslinkable group, will be described. To do. Formula (1):

And formula (2):

In A, A represents a divalent aromatic group or an aliphatic group. A specifically represents a divalent aromatic group or aliphatic group that is a residue of an aromatic or aliphatic diamine component that constitutes the repeating units represented by formulas (1) and (2). .

  Although it does not specifically limit as an aromatic diamine component which can be used for this invention, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoxylene, 2 , 4-diaminodurene, 4,4′-diaminodiphenylmethane, 4,4′-methylenebis (2-methylaniline), 4,4′-methylenebis (2-ethylaniline), 4,4′-methylenebis (2,6 -Dimethylaniline), 4,4'-methylenebis (2,6-diethylaniline), 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diamino Diphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl Sulfone, 4,4′-diaminobenzophenone, 3,3′-diaminobenzophenone, 4,4′-diaminobenzanilide, benzidine, 3,3′-dihydroxybenzidine, 3,3′-dimethoxybenzidine, o-tolidine, m -Tolidine, 2,2'-bis (trifluoromethyl) benzidine, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3- Aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 2,2 -Bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) Phenyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, p- terphenyl-phenylenediamine, and the like as examples. Two or more of these may be used in combination.

  The aliphatic diamine component that can be used in the present invention is not particularly limited, and examples thereof include 1,4-cyclohexanediamine, 4,4′-methylenebis (cyclohexylamine), 1,4-cyclohexanebis (methylamine), 2, 5-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 3,8-bis (aminomethyl) tricyclo [5.2 .1.0] decane, 1,3-diaminoadamantane, 2,2-bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propanediamine, , 4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethyle Diamine, 1,8-octamethylene diamine, 1,9-nonamethylenediamine, and the like. Two or more of these may be used in combination. In order to maintain high thermal stability and high glass transition temperature, it is preferable to use an alicyclic diamine such as 1,4-diaminocyclohexane as the aliphatic diamine.

  The degree of polymerization of the repeating units represented by formulas (1) and (2) is not particularly limited, but is, for example, in the range of 1 to 40, and preferably in the range of 5 to 20.

  In the esterimide oligomer precursor and esterimide oligomer having a repeating unit represented by the formulas (1) and (2) of the present invention, the thermally crosslinkable group that seals the terminal is a dicarboxylic acid having a thermally crosslinkable group. It means a group that is the residue of an acid anhydride component or a monoamine component. The dicarboxylic acid anhydride component that can be used is not particularly limited as long as it is a thermal crosslinking reactive group, for example, a dicarboxylic acid anhydride having a carbon-carbon unsaturated bond. Specifically, nadic acid anhydride, Examples include maleic anhydride, citraconic anhydride, 4-phenylethynylphthalic anhydride, 4-ethynylphthalic anhydride, 4-vinylphthalic anhydride, and the like.

  Moreover, the monoamine component that can be used is not particularly limited as long as it is a monoamine compound having a thermally crosslinkable group, for example, a carbon-carbon unsaturated bond, and specifically, 4-phenylethynylaniline, 4-ethynyl. Examples include aniline, 3-ethynylaniline, 2-ethynylaniline, 4-aminostyrene, 3-aminostyrene and the like.

  The synthesis of the ester imide oligomer precursor having a repeating unit represented by the formula (1) is specifically performed as follows. First, 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride, which is a tetracarboxylic dianhydride component that induces a tetracarboxylic acid residue, constituting the repeating unit represented by the formula (1) :

And the diamine component and the thermally crosslinkable group component are prepared. The tetracarboxylic dianhydride component can be synthesized, for example, from 2,2′-biphenol and trimellitic anhydride chloride according to a known method, and details thereof can be found in, for example, Japanese Patent Application No. 2004-115129. Are listed. On the other hand, the diamine component, the thermally crosslinkable group component and the like are available as reagents from Aldrich, for example, or can be synthesized from available reagents according to known methods.

  Thermal crosslinking as an embodiment of the synthesis of an ester imide oligomer precursor, having a repeating unit represented by the formula (1) of the present invention and having its terminal end sealed with a thermally crosslinkable group The case where the functional group component is the dicarboxylic anhydride component will be outlined below. That is, the following formula (1 '):

(Wherein A represents a divalent aromatic group or aliphatic group, B is a residue of a dicarboxylic acid anhydride having a thermally crosslinkable group, and n is the degree of polymerization). In the case of synthesis of an esterimide oligomer precursor, first, a diamine component (X + (Y / 2) mol) is dissolved in a polymerization solvent, and a predetermined amount of 2,2′-di (4-trimellitoyloxy) biphenyl is dissolved in this solution. The dianhydride powder (X mol) and the dicarboxylic acid anhydride (Y mol) are gradually added and stirred at room temperature for 0.5 to 24 hours using a mechanical stirrer. Under the present circumstances, the sum total of each monomer density | concentration in a reaction solution is 5 to 50 weight%, Preferably it is 10 to 40 weight%. By performing polymerization in this monomer concentration range, a uniform esterimide oligomer precursor solution can be obtained. Content of the dicarboxylic anhydride = ((Y / 2) / (X + (Y / 2)) × 100 (%) is in the range of 2 to 50%, more preferably in the range of 3 to 40%. Yes, more preferably in the range of 4-40%.

  From this ester imide oligomer precursor solution, the conventional unit as described below has a repeating unit represented by the formula (2) of the present invention and its end is sealed with a thermally crosslinkable group. As one aspect of the esterimide oligomer that is characterized, the following formula (2 ′):

The ester imide oligomer shown by can be obtained.

  Another embodiment of the synthesis of an ester imide oligomer precursor, characterized in that it has a repeating unit represented by the formula (1) of the present invention and its end is sealed with a thermally crosslinkable group. The case where the thermally crosslinkable group component is the monoamine component will be outlined below. That is, the following formula (1 ″):

(Wherein A represents a divalent aromatic group or aliphatic group, D is a residue of a monoamine component having a thermally crosslinkable group, and n is the degree of polymerization) In the synthesis of the oligomer precursor, first, the diamine component (X′mol) and the monoamine (Y′mol) are dissolved in a polymerization solvent, and 2,2′-di (4-trimellitoyloxy) biphenyl is dissolved in this solution. The dianhydride powder (X ′ + (Y ′ / 2) mol) is gradually added and stirred at room temperature for 0.5-24 hours using a mechanical stirrer. Under the present circumstances, the sum total of each monomer density | concentration in a reaction solution is 5 to 50 weight%, Preferably it is 10 to 40 weight%. By performing polymerization in this monomer concentration range, a uniform esterimide oligomer precursor solution can be obtained. Content of thermal crosslinking reactive monoamine = ((Y ′ / 2) / (X ′ + (Y ′ / 2)) × 100 (%) is in the range of 2 to 50%, more preferably 3 to 40. %, More preferably 4 to 40%.

  From this ester imide oligomer precursor solution, the conventional unit as described below has a repeating unit represented by the formula (2) of the present invention and its end is sealed with a thermally crosslinkable group. As one aspect of the esterimide oligomer that is characterized, the following formula (2 ″):

The ester imide oligomer shown by can be obtained.

  As a polymerization solvent, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, dimethyl sulfoxide, γ-butyrolactone, 1,3- Aprotic such as dimethyl-2-imidazolidinone, 1,2-dimethoxyethane-bis (2-methoxyethyl) ether, terahydrofuran, 1,4-dioxane, picoline, pyridine, acetone, chloroform, toluene, xylene Solvents and protic solvents such as phenol, o-cresol, m-cresol, p-cresol, o-chlorophenol, m-chlorophenol, p-chlorophenol can be used. These solvents may be used alone or in combination of two or more.

  Tetracarboxylic acid dianhydrides other than 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride in order to improve some of the required properties of the cured esterimide oligomer according to the present invention Physical components can be used partially. Although not particularly limited, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3, 3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) ) Hexafluoropropanoic acid dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propanoic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like. These may be used alone or in combination of two or more. These tetracarboxylic dianhydrides are used in the range of 0 to 50 mol%, more preferably 0 to 40 mol%, based on the total amount of tetracarboxylic dianhydrides.

  The ester imide oligomer according to the present invention, its precursor, and the end groups having no reactivity other than the thermally crosslinkable group are partially used as long as the reactivity and required properties of these cured products are not significantly impaired. There is no problem. Examples of usable end-capping agents include, but are not limited to, phthalic anhydride, 3,4,5,6-tetrachlorophthalic anhydride, 3,4,5,6-tetrafluorophthalic anhydride, aniline, etc. As mentioned. These non-reactive end groups are used in the range of 0 to 50 mol%, more preferably 0 to 40 mol%, based on the total amount of end groups.

  Polymer dissolution accelerators that are often added during polymerization of the polyimide precursor, that is, metal salts such as lithium bromide and lithium chloride, do not need to be used in the esterimide oligomer precursor polymerization reaction according to the present invention. If even a trace amount of metal ions remains in the insulating material, the reliability as an electronic device is remarkably lowered. Therefore, the use of metal salts is not preferable particularly when the use is directed to such applications.

  A solid esterimide oligomer precursor may be isolated from the obtained esterimide oligomer precursor solution by a conventional method, but the obtained esterimide oligomer precursor solution is used as it is as a varnish, and a glass plate, a copper plate, stainless steel You may apply | coat on board | substrates, such as a board, an aluminum board, a silicon board, a polyester film, and a polyimide film, and may make it dry for 0.5 to 24 hours at the temperature of 40 to 180 degreeC. By heat-treating the obtained esterimide oligomer precursor film at a temperature of 200 ° C. to 430 ° C., preferably 250 ° C. to 400 ° C. in an air, in an inert gas atmosphere such as nitrogen, or in vacuum. An ester imide oligomer film is obtained. Furthermore, an ester imide oligomer film | membrane can be obtained also by the method of immersing an ester imide oligomer precursor film | membrane in the dehydration cyclization reagent which is mentioned later.

  Since the ester imide oligomer according to the present invention is soluble, after synthesizing the ester imide oligomer precursor as described above, the solution is subsequently heated to reflux for imidization to obtain a uniform ester imide oligomer solution. Can do. It can also be chemically imidized. That is, while stirring the esterimide oligomer precursor solution vigorously, a dehydrating agent such as acetic anhydride and a basic catalyst such as pyridine or triethylamine are added dropwise thereto to obtain a uniform esterimide oligomer solution.

  Esterimide is also obtained by a method (one-pot polymerization method) in which a monomer is dissolved in m-cresol containing γ-picoline or the like and m-cresol containing xylene and heated by azeotropic removal at 160 ° C. for several hours while azeotropically removing water as a by-product. An ester imide oligomer can be synthesized without going through an oligomer precursor.

  The ester imide oligomer powder can be taken out as an ester imide oligomer powder by dripping the ester imide oligomer solution obtained by heating reflux, chemical imidization or one-pot method as described above onto a precipitating agent such as water or alcohol. By re-dissolving this esterimide oligomer powder or esterimide oligomer film obtained by thermal imidization in an aprotic organic solvent such as N-methyl-2-pyrrolidone, a uniform esterimide oligomer solution can be obtained. it can.

  While ordinary polyimides are almost insoluble in organic solvents, the ester imide oligomers of the present invention have high organic solvent solubility, such as aprotic organic solvents such as dimethyl sulfoxide, N-methyl-2-pyrrolidone. , N, N-dimethylacetamide, dimethylformamide and other organic solvents have a solubility of 5% by weight or more at 25 ° C. Specifically, N-methyl-2-pyrrolidone has a solubility of 5% by weight or more, particularly 10% by weight or more, particularly preferably 20% by weight or more at 25 ° C.

  The intrinsic viscosity of the esterimide oligomer of the present invention measured in N, N-dimethylacetamide at 30 ° C. and a concentration of 0.5% by weight is preferably in the range of 0.05 to 2.0 dL / g. More preferably, it is in the range of 1 to 1.0 dL / g. If the intrinsic viscosity exceeds 2.0 dL / g, the melt viscosity becomes too high and the desired heat processability (thermoplasticity) may be significantly impaired. If it is less than 0.05 dL / g, the ester imide oligomer particles may be too small during the ester imide oligomer isolation step, which may require a long time for the filtration step.

  Since the solution of the ester imide oligomer of the present invention has extremely high storage stability like the precursor solution, it is not necessary to add a metal salt dissolution accelerator such as lithium chloride, which is not preferable for use as an electronic material.

  The obtained ester imide oligomer solution was applied to a substrate such as a glass plate, a copper plate, a stainless plate, an aluminum plate, a silicon plate, a polyester film, and a polyimide film as it was as a varnish as described above. The ester imide oligomer film can be obtained by drying at a temperature of 0.5 to 24 hours and volatilizing the solvent.

  In the ester imide oligomer film, additives such as an oxidation stabilizer, a terminal blocking agent, a filler, a silane coupling agent, a photosensitizer, a photopolymerization initiator, and a sensitizer may be mixed as necessary. .

  A cured film having high toughness can be formed on a substrate by heat-treating the obtained esterimide oligomer film at 230 to 450 ° C., preferably 250 to 430 ° C. in air, nitrogen or vacuum. For example, if an ester imide oligomer film according to the present invention is formed on a polyimide surface of a polyimide / copper foil laminate, and then another copper foil is thermocompression bonded to the oligomer film surface in a similar temperature range, the ester imide oligomer layer It becomes possible to produce a double-sided copper clad laminate through a melting / thermosetting reaction.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

<Intrinsic viscosity>
With respect to the 0.5 wt% esterimide oligomer precursor solution, the intrinsic viscosity at 30 ° C. was measured using an Ostwald viscometer.
<Glass transition temperature: Tg>
About the thermosetting film | membrane of the ester imide oligomer obtained in each Example, the frequency 0.1Hz and the temperature increase rate 5 degree-C / min by dynamic viscoelasticity measurement using the thermomechanical analyzer (TMA4000) by Bruker AX. The glass transition temperature was determined from the loss energy peak temperature in the temperature rising process at.
<Linear thermal expansion coefficient: CTE>
By using a thermomechanical analyzer (TMA4000) manufactured by Bruker Ax, the ester imide oligomer obtained in each example at a load of 0.5 g / thickness of 1 μm and a heating rate of 5 ° C./min was measured by thermomechanical analysis. The linear thermal expansion coefficient (average value in the range of 100 to 200 ° C.) was determined from the elongation of the test piece (5 mm × 20 mm) of the thermosetting film.
<Dielectric constant>
Based on the average refractive index n _av = (2n _in + n _out ) / 3 of the thermosetting film of the ester imide oligomer obtained in each example using an Abbe refractometer (Abbe 4T) manufactured by Atago Co., The dielectric constant (ε) at 1 MHz was calculated (ε = 1.1 × n _av ² ).
<Elastic modulus, elongation at break>
Using a tensile tester (Tensilon UTM-2) manufactured by Toyo Baldwin Co., Ltd., a tensile test (stretching speed: 8 mm / min) of a test piece (3 mm × 30 mm) of a thermosetting film of an esterimide oligomer obtained in each example The elastic modulus was determined from the initial gradient of the stress-strain curve, and the elongation at break (%) was determined from the elongation at the time when the film was broken.
<5% weight loss temperature: T _d ⁵ >
The heat of the ester imide oligomer obtained in each example in a temperature rising process at a heating rate of 10 ° C./min in nitrogen or air using a thermogravimetric analyzer (TG-DTA2000) manufactured by Bruker Ax The temperature when the initial weight of the cured film sample was reduced by 5% was measured.
<Melt viscosity measurement>
Esterimide oligomer powder was molded into a disk shape with a diameter of 2.5 cm and a thickness of 1.7 mm, and heated in a nitrogen atmosphere using a parallel plate viscoelasticity measuring device (RDSII) manufactured by Rheometric Scientific. The melt viscosity was measured at a rate of 4 ° C./min, a strain of 0.1%, and a frequency of 1 Hz.

Example 1
In a well-dried closed reaction vessel with a stirrer, 11 mmol of p-phenylenediamine was placed and dissolved in N-methyl-2-pyrrolidone sufficiently dehydrated with Molecular Sieves 4A, and then 2,2′-di (4- 10 mmol of trimellitoyloxy) biphenyl dianhydride powder and 2 mmol of nadic acid anhydride were gradually added with stirring. At this time, the amount of solvent was adjusted so that the monomer concentration was 30% by weight. The mixture was stirred at room temperature for 24 hours to obtain a uniform and viscous esterimide oligomer precursor solution. The intrinsic viscosity was 0.140 dL / g. This esterimide oligomer precursor solution was applied to a glass substrate and dried at 60 ° C. for 2 hours to obtain an esterimide oligomer precursor film. This was subjected to thermal imidization at 230 ° C. for 1 hour on a substrate, followed by heat treatment at 350 ° C. for 1 hour to obtain a 20 μm thick esterimide cured film. The cured esterimide film showed toughness with no breaks or cracks even after a 180 ° bending test. The esterimide oligomer before thermosetting is soluble in various organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and more than 300 ° C. in the temperature rising process. However, after thermosetting, it was insoluble in any solvent and did not melt at all. Table 1 shows the physical properties of the thermosetting film. As a result of dynamic viscoelasticity measurement of the cured esterimide film, the glass transition temperature was 270 ° C. Other film properties are linear thermal expansion coefficient 54.4 ppm / K, 5% weight loss temperature is 449 ° C. in nitrogen, 420 ° C. in air, dielectric constant is 3.07, tensile modulus is 2.4 GPa, elongation at break is 7 %Met. Thus, the ester imide oligomer of the present invention exhibits excellent organic solvent solubility and thermoplasticity, and the cured ester imide film obtained from the polyester imide oligomer has a high glass transition temperature, high thermal stability, and sufficient Showed good film toughness. An infrared absorption spectrum of the obtained esterimide cured film is shown in FIG.

(Example 2)
In the same manner as described in Example 1, an ester imide oligomer precursor was synthesized, and a mixed solution of acetic anhydride / pyridine (volume ratio 7/3) was dripped into this solution with vigorous stirring to perform chemical imidization. After stirring for 30 minutes, the reaction solution was dropped into methanol to cause precipitation, and further, washing with a large amount of methanol was repeated, followed by filtration and vacuum drying at 140 ° C. to obtain an ester imide oligomer powder. From the infrared absorption spectrum, it was confirmed that the chemical imidization was completed. This was redissolved in N-methyl-2-pyrrolidone at 10% by weight, applied to a glass substrate, and heat-treated at 350 ° C. for 1 hour to produce a 20 μm thick esterimide cured film. The ester imide oligomer obtained by chemical imidization (before curing) was soluble in various organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, and N, N-dimethylformamide. It was insoluble in any solvent after thermosetting. In addition, the melt viscosity of the ester imide oligomer (before curing) showed a minimum value (1147 poise) at 325 ° C. during the temperature rising process and showed high melt fluidity, but the thermosetting reaction rapidly progressed as the temperature further increased. The melt viscosity increased rapidly. Thus, it did not melt at all after thermosetting. The cured film obtained via chemical imidization showed film properties equivalent to those described in Example 1.

(Example 3)
A cured esterimide film in the same manner as described in Example 1 except that 4-phenylethynylphthalic anhydride was used in place of nadic acid anhydride as a heat-crosslinkable group component and heat curing was performed at 400 ° C. Was made. Table 1 shows the film properties.

Example 4
Similar to the method described in Example 1, except that maleic anhydride was used in place of nadic acid anhydride and 4,4′-oxydianiline was used in place of p-phenylenediamine as the thermally crosslinkable group component. An ester imide oligomer precursor was synthesized. The intrinsic viscosity was as very low as 0.076 dL / g, and when a thermosetting film was similarly produced using this, a tough cured film was obtained. The glass transition temperature of this cured film was 234 ° C.

(Example 5)
As the tetracarboxylic dianhydride component, 8 mmol of 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride and 2 mmol of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride were used. Except for the above, an esterimide cured film was produced in the same manner as in the method described in Example 1. Table 1 shows the film properties.

(Example 6)
As the tetracarboxylic dianhydride component, 5 mmol of 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride and 5 mmol of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride were used. Except for the above, an esterimide cured film was produced in the same manner as in the method described in Example 1. Table 1 shows the film properties.

(Example 7)
Similar to the method described in Example 1, using 8 mmol of 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride and 2 mmol of pyromellitic dianhydride as the tetracarboxylic dianhydride component. An ester imide oligomer precursor was synthesized. The intrinsic viscosity was 0.351 dL / g. The glass transition temperature of the cured film prepared according to the method described in Example 1 was 275 ° C.

(Comparative Example 1)
An ester imide cured film was prepared in the same manner as described in Example 1 except that nadic acid anhydride was not used as the thermally crosslinkable group component and phthalic anhydride was used instead. Had many cracks and did not show any toughness. This is because non-reactive phthalic anhydride was used as the end group, so that the thermal crosslinking reaction did not occur even after heat treatment, and the oligomer had a low molecular weight. Since the membrane was extremely fragile, physical properties were not evaluated. On the other hand, when the heat treatment temperature was changed from 350 ° C. to 400 ° C., the film physical properties were measured because the film toughness was slightly improved (Table 1). The glass transition temperature was 250 ° C., which was 20 ° C. lower than the cured film described in Example 1. This is because non-reactive phthalic anhydride was used as a terminal group.

(Comparative Example 2)
As the tetracarboxylic dianhydride component, 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride is not used. Instead, 3,3 ′, 4,4′-biphenyltetracarboxylic acid A cured imide film was prepared in the same manner as described in Example 1 except that the anhydride was used. However, since the obtained cured film had many cracks and was extremely fragile, the film toughness was not measurable. This is because 2,2′-di (4-trimellitoyloxy) biphenyl dianhydride was not used as the tetracarboxylic dianhydride component, and therefore it hardly melted during the temperature rising process. As the tetracarboxylic dianhydride component, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride and 3,3 ′, 4,4′-biphenyl ether tetracarboxylic acid The same was true when the anhydride was used.

(Comparative Example 3)
A polyimide was prepared from the same tetracarboxylic dianhydride and aromatic diamine as in Example 1 as follows.
After putting 10 mmol of p-phenylenediamine in a well-dried sealed reaction vessel with a stirrer and dissolving in 16 mL of N, N-dimethylacetamide sufficiently dehydrated with molecular sieves 4A, 2,2′-di (4- 10 mmol of trimellitoyloxy) biphenyl dianhydride powder was gradually added with stirring. After 10 minutes, since the solution viscosity increased rapidly, 4 mL of solvent was added for dilution. Furthermore, it stirred at room temperature for 24 hours and obtained the transparent, uniform and viscous polyimide precursor solution. This polyimide precursor solution did not precipitate or gel at all even when allowed to stand at room temperature and −20 ° C. for one month, and showed extremely high solution storage stability. Intrinsic viscosity was 0.53 dL / g. A polyimide precursor film obtained by applying this polyimide precursor solution to a glass substrate and drying at 60 ° C. for 1 hour is subjected to thermal imidization at 300 ° C. under reduced pressure for 1 hour on the substrate to obtain a transparent film having a thickness of 20 μm. A polyimide film was obtained. Even when this polyimide film was completely folded, it did not break and showed toughness. The intrinsic viscosity was almost the same as that of the polyimide precursor. As a result of the dynamic viscoelasticity measurement of the polyimide film, a glass transition point was observed at 243 ° C. The coefficient of linear thermal expansion (average value between 100 ° C. and 200 ° C.) was 66 ppm / K, and the 5% weight loss temperature (temperature increase rate: 10 ° C./min) was 433 ° C. in nitrogen and 430 ° C. in air.

  The ester imide oligomer of the present invention exhibits high processability (melt flowability and organic solvent solubility), and its thermoset film is practically beneficial that satisfies both high glass transition temperature and high toughness at the same time. Application to heat-resistant adhesives in devices is possible.

It is an infrared absorption spectrum of the esterimide cured film described in Example 1 (manufactured by JASCO Corporation: FT / IR-5300).

Claims (5)

Formula (1):

(Wherein A represents a divalent aromatic group or aliphatic group), and the terminal thereof is sealed with a thermally crosslinkable group, Esterimide oligomer precursor. Formula (2):

(Wherein A represents a divalent aromatic group or aliphatic group), and the terminal thereof is sealed with a thermally crosslinkable group, Esterimide oligomer.   A thermoset obtained by subjecting the esterimide oligomer according to claim 2 to a thermal crosslinking reaction.   The method for producing an ester imide oligomer according to claim 2, wherein the ester imide oligomer precursor according to claim 1 is subjected to a dehydration cyclization reaction by heating or a dehydrating reagent. A varnish containing the ester imide oligomer according to claim 2.

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