Polyimide resin composition

Abstract

The polyimide resin composition contains a polyimide resin (A) that contains a repeating structural unit represented by the following formula (1) and a repeating structural unit represented by the following formula (2), wherein the content of the repeating structural unit of formula (1) relative to the total of the repeating structural units of formula (1) and formula (2) is 20 to 70 mol %, and a metal phosphinate salt-based flame retardant (B). (R1 is a divalent group having 6 to 22 carbon atoms and containing at least one alicyclic hydrocarbon structure. R2 is a divalent chain aliphatic group having 5 to 16 carbon atoms. X1 and X2 are each independently a tetravalent group having 6 to 22 carbon atoms and containing at least one aromatic ring.)

Description

Technical Field

[0001] The present invention relates to a polyimide resin composition.

Background Art

[0002] Polyimide resins are useful engineering plastics having high thermal stability, high strength, and high solvent resistance due to the rigidity of the molecular chain, resonance stabilization, and strong chemical bonds, and are applied in a wide range of fields. In addition, polyimide resins having crystallinity are expected to be used as metal substitutes because their heat resistance, strength, and chemical resistance can be further improved. However, polyimide resins have the problem that, while having high heat resistance, they do not exhibit thermoplasticity and have low moldability.

[0003] As polyimide molding materials, high heat-resistant resins such as Vespel (registered trademark) are known (Patent Document 1), but since the fluidity is extremely low even at high temperatures, molding is difficult, and it is necessary to perform molding under high temperature and high pressure conditions for a long time, which is disadvantageous in terms of cost. On the other hand, a resin having a melting point like a crystalline resin and having fluidity at high temperatures can be easily and inexpensively molded.

[0004] Therefore, in recent years, polyimide resins having thermoplasticity have been reported. Thermoplastic polyimide resins are excellent in moldability in addition to the heat resistance inherent in polyimide resins. Therefore, thermoplastic polyimide resins can also be applied to molded articles used in harsh environments where general-purpose thermoplastic resins such as nylon and polyester cannot be applied.

[0005] In order to apply to applications where flame retardancy is required, studies have also been made to improve the flame retardancy by adding a flame retardant to the thermoplastic polyimide resin. For example, Patent Document 2 discloses an adhesive film provided with an adhesive layer containing a thermoplastic polyimide and a flame retardant on at least one side of an insulating film. Patent Document 3 discloses a flame retardant composition comprising a mixture obtained by dry blending a resin having an average particle size of 1000 μm or less, such as polyimide, with magnesium hydroxide or aluminum hydroxide. Patent Documents 4 and 5 also describe that additives such as flame retardants may be blended with a polyimide resin containing a predetermined repeating unit to form a resin composition.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0007] Although the thermoplastic polyimide resin containing an aliphatic structure disclosed in Patent Documents 4 and 5 is superior in moldability to the wholly aromatic polyimide resin, it tends to be inferior in flame retardancy. Therefore, for example, it has been difficult to impart a high flame retardancy at the V-0 level in the UL94 standard, which is a flame retardancy test standard for plastic materials issued by Underwriters Laboratories. If the amount of the flame retardant added to the thermoplastic polyimide resin is increased, the flame retardancy will be improved, but on the other hand, problems such as the occurrence of bleed-out of the flame retardant and the deterioration of the appearance will occur. An object of the present invention is to provide a polyimide resin composition having moldability and capable of achieving both high flame retardancy and good appearance.

Means for Solving the Problems

[0008] The inventors of the present invention have found that a polyimide resin composition containing a polyimide resin in which specific different polyimide structural units are combined at a specific ratio and a specific flame retardant can solve the above problems. That is, the present invention provides a polyimide resin composition containing a polyimide resin (A) containing a repeating structural unit represented by the following formula (1) and a repeating structural unit represented by the following formula (2), wherein the content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is 20 to 70 mol%, and a metal salt of phosphinic acid-based flame retardant (B). [Chemical formula] (R1 is a divalent group having 6 to 22 carbon atoms containing at least one alicyclic hydrocarbon structure. R2 is a divalent chain aliphatic group having 5 to 16 carbon atoms. X1 and X2 are each independently a tetravalent group having 6 to 22 carbon atoms containing at least one aromatic ring.) [Advantages of the Invention]

[0009] The polyimide resin composition of the present invention is excellent in moldability and can achieve both high flame retardancy and good appearance. The polyimide resin composition of the present invention can be applied to various industrial members such as automobiles, railways, and aviation, members for household electrical appliances, or their casings. Specifically, it can be applied to gears, bearings, cutting members, screws, nuts, packings, inspection IC sockets, belts, coating materials for electric wires, coverlay films, members for semiconductor manufacturing equipment, medical instruments, coating materials for fishing rods and reels, stationery, carbon UD tapes, heat insulating materials, etc. Further, since the molded body also has good mechanical properties and heat resistance, it can also be applied to various metal replacements such as aluminum alloys and magnesium alloys. [Modes for Carrying Out the Invention]

[0010] [Polyimide Resin Composition] The polyimide resin composition of the present invention contains a repeating structural unit represented by the following formula (1) and a repeating structural unit represented by the following formula (2), and the content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is 20 to 70 mol%. It is a polyimide resin composition containing a polyimide resin (A) and a metal phosphinate-based flame retardant (B). [Chemical formula] (R1 is a divalent group having 6 to 22 carbon atoms containing at least one alicyclic hydrocarbon structure. R2 is a divalent linear aliphatic group having 5 to 16 carbon atoms. X1 and X2 are each independently a tetravalent group having 6 to 22 carbon atoms containing at least one aromatic ring.) The polyimide resin composition of the present invention exhibits thermoplasticity by containing a polyimide resin (A) formed by combining specific different polyimide structural units in the above specific ratio, and becomes a resin composition excellent in moldability. Further, by combining the polyimide resin (A) and a specific flame retardant (B), high flame retardancy and good appearance can be achieved in the obtained polyimide resin composition and its molded article. When a flame retardant other than the metal phosphinate-based flame retardant (B) is used, at least one of flame retardancy and appearance tends to be inferior.

[0011] <Polyimide resin (A)> The polyimide resin (A) used in the present invention contains a repeating structural unit represented by the following formula (1) and a repeating structural unit represented by the following formula (2), and the content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is 20 to 70 mol%. [Chemical formula] (R1 is a divalent group having 6 to 22 carbon atoms containing at least one alicyclic hydrocarbon structure. R2 is a divalent linear aliphatic group having 5 to 16 carbon atoms. X1 and X2 are each independently a tetravalent group having 6 to 22 carbon atoms containing at least one aromatic ring.)

[0012] The polyimide resin (A) used in the present invention is a thermoplastic resin, and its form is preferably powder or pellets. The thermoplastic polyimide resin is distinguished from a polyimide resin having no glass transition temperature (Tg), or a polyimide resin that decomposes at a temperature lower than the glass transition temperature, which is formed by closing the imide ring after molding in the state of a polyimide precursor such as polyamic acid.

[0013] The repeating structural unit of formula (1) will be described in detail below. R1 is a divalent group having 6 to 22 carbon atoms containing at least one alicyclic hydrocarbon structure. Here, the alicyclic hydrocarbon structure means a ring derived from an alicyclic hydrocarbon compound, and the alicyclic hydrocarbon compound may be saturated or unsaturated, and may be monocyclic or polycyclic. Examples of the alicyclic hydrocarbon structure include cycloalkane rings such as cyclohexane rings, cycloalkene rings such as cyclohexene, bicycloalkane rings such as norbornane rings, and bicycloalkene rings such as norbornene, but are not limited thereto. Among these, a cycloalkane ring is preferable, a cycloalkane ring having 4 to 7 carbon atoms is more preferable, and a cyclohexane ring is further preferable. The carbon number of R1 is 6 to 22, preferably 8 to 17. R1 contains at least one alicyclic hydrocarbon structure, preferably 1 to 3.

[0014] R1 is preferably a divalent group represented by the following formula (R1-1) or (R1-2).

Chemical formula

[0015] R1 is preferably a divalent group represented by the following formula (R1-3).

Chemical formula

[0016] X1 is a tetravalent group having 6 to 22 carbon atoms and containing at least one aromatic ring. The aromatic ring may be a monocyclic ring or a condensed ring, and examples include a benzene ring, a naphthalene ring, an anthracene ring, and a tetracene ring, but are not limited thereto. Among these, a benzene ring and a naphthalene ring are preferable, and a benzene ring is more preferable. The carbon number of X1 is 6 to 22, preferably 6 to 18. X1 contains at least one aromatic ring, preferably 1 to 3 aromatic rings.

[0017] X1 is preferably a tetravalent group represented by any one of the following formulas (X-1) to (X-4).

Chemical formula

[0018] X1 is particularly preferably a tetravalent group represented by the following formula (X-5) or (X-6).

Chemical formula

[0019] Next, the repeating structural unit of formula (2) will be described in detail below. R2 is a divalent chain aliphatic group having 5 to 16 carbon atoms, preferably 6 to 14 carbon atoms, more preferably 7 to 12 carbon atoms, and still more preferably 8 to 10 carbon atoms. Here, the chain aliphatic group means a group derived from a chain aliphatic compound, and the chain aliphatic compound may be saturated or unsaturated, linear or branched, and may contain a heteroatom such as an oxygen atom. R2 is preferably an alkylene group having 5 to 16 carbon atoms, more preferably an alkylene group having 6 to 14 carbon atoms, still more preferably an alkylene group having 7 to 12 carbon atoms, and particularly preferably an alkylene group having 8 to 10 carbon atoms. The alkylene group may be a linear alkylene group or a branched alkylene group, but is preferably a linear alkylene group. R2 is preferably at least one selected from the group consisting of an octamethylene group and a decamethylene group, and particularly preferably an octamethylene group.

[0020] Another preferred embodiment of R2 includes a divalent chain aliphatic group having 5 to 16 carbon atoms and containing an ether group. The number of carbon atoms is preferably 6 to 14, more preferably 7 to 12, and still more preferably 8 to 10. Among them, it is preferably a divalent group represented by the following formula (R2-1) or (R2-2).

Chemical formula

[0021] X2 is defined in the same manner as X1 in the formula (1), and the preferred embodiments are also the same.

[0022] The content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural units of the formula (1) and the repeating structural unit of the formula (2) is 20 to 70 mol%. When the content ratio of the repeating structural unit of the formula (1) is within the above range, it is possible to sufficiently crystallize the polyimide resin even in a general injection molding cycle. If the content ratio is less than 20 mol%, the moldability deteriorates, and if it exceeds 70 mol%, the crystallinity decreases, resulting in a decrease in heat resistance. The content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural units of the formula (1) and the repeating structural unit of the formula (2) is preferably 65 mol% or less, more preferably 60 mol% or less, still more preferably 50 mol% or less, from the viewpoint of exhibiting high crystallinity. Among them, the content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural units of the formula (1) and the repeating structural unit of the formula (2) is preferably 20 mol% or more and less than 40 mol%. Within this range, the crystallinity of the polyimide resin (A) becomes high, and a resin composition having more excellent heat resistance can be obtained. From the viewpoint of moldability, the above content ratio is preferably 25 mol% or more, more preferably 30 mol% or more, still more preferably 32 mol% or more, and from the viewpoint of exhibiting high crystallinity, it is more preferably 35 mol% or less.

[0023] The total content ratio of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) with respect to all the repeating structural units constituting the polyimide resin (A) is preferably 50 to 100 mol%, more preferably 75 to 100 mol%, still more preferably 80 to 100 mol%, and even more preferably 85 to 100 mol%.

[0024] The polyimide resin (A) may further contain a repeating structural unit of the following formula (3). In that case, the content ratio of the repeating structural unit of the formula (3) with respect to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is preferably 25 mol% or less. On the other hand, the lower limit is not particularly limited as long as it exceeds 0 mol%. From the viewpoint of improving heat resistance, the content ratio is preferably 5 mol% or more, more preferably 10 mol% or more. On the other hand, from the viewpoint of maintaining crystallinity, it is preferably 20 mol% or less, more preferably 15 mol% or less.

Chemical formula

[0025] R3 is a divalent group having 6 to 22 carbon atoms containing at least one aromatic ring. The aromatic ring may be a monocyclic ring or a condensed ring, and examples include a benzene ring, a naphthalene ring, an anthracene ring, and a tetracene ring, but are not limited thereto. Among these, a benzene ring and a naphthalene ring are preferable, and a benzene ring is more preferable. The carbon number of R3 is 6 to 22, preferably 6 to 18. R3 contains at least one aromatic ring, preferably 1 to 3 aromatic rings. Further, a monovalent or divalent electron-withdrawing group may be bonded to the aromatic ring. Examples of the monovalent electron-withdrawing group include a nitro group, a cyano group, a p-toluenesulfonyl group, a halogen, a halogenated alkyl group, a phenyl group, and an acyl group. Examples of the divalent electron-withdrawing group include an alkylene fluoride group (e.g., -C(CF3)2-, -(CF2) p -(where p is an integer from 1 to 10)) and other halogenated alkylene groups, as well as -CO-, -SO2-, -SO-, -CONH-, -COO-, etc.

[0026] R3 is preferably a divalent group represented by the following formula (R3-1) or (R3-2). [Chemical formula] (m 31 and m 32 are each independently an integer from 0 to 2, preferably 0 or 1. m 33 and m 34 are each independently an integer from 0 to 2, preferably 0 or 1. R 21 , R 22 , and R 23 are each independently an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or an alkynyl group having 2 to 4 carbon atoms. p 21 , p 22 and p 23 are integers from 0 to 4, preferably 0. L 21 is a single bond, an ether group, a carbonyl group, or an alkylene group having 1 to 4 carbon atoms.) Since R3 is a divalent group having 6 to 22 carbon atoms and containing at least one aromatic ring, m 31 , m 32 , R 21 and p 21 in formula (R3-1) are selected so that the number of carbon atoms in the divalent group represented by formula (R3-1) falls within the range of 6 to 22. Similarly, L 21 , m 33 , m 34 , R 22 , R23 , p 22 and p 23 are selected such that the number of carbon atoms in the divalent group represented by the formula (R3-2) falls within the range of 12 to 22.

[0027] X3 is defined in the same manner as X1 in formula (1), and the preferred embodiments are also the same.

[0028] The polyimide resin (A) may further contain a repeating structural unit represented by the following formula (4).

Chemical formula

[0029] There is no particular limitation on the terminal structure of the polyimide resin (A), but it preferably has a linear aliphatic group having 5 to 14 carbon atoms at the terminal. The linear aliphatic group may be saturated or unsaturated, and may be linear or branched. When the polyimide resin (A) has the above specific group at the terminal, a resin composition excellent in heat aging resistance can be obtained. Examples of the saturated linear aliphatic group having 5 to 14 carbon atoms include n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, lauryl group, n-tridecyl group, n-tetradecyl group, isopentyl group, neopentyl group, 2-methylpentyl group, 2-methylhexyl group, 2-ethylpentyl group, 3-ethylpentyl group, isooctyl group, 2-ethylhexyl group, 3-ethylhexyl group, isononyl group, 2-ethyloctyl group, isodecyl group, isododecyl group, isotridecyl group, isotetradecyl group, etc. Examples of the unsaturated chain aliphatic group having 5 to 14 carbon atoms include 1-pentenyl group, 2-pentenyl group, 1-hexenyl group, 2-hexenyl group, 1-heptenyl group, 2-heptenyl group, 1-octenyl group, 2-octenyl group, nonenyl group, decenyl group, dodecenyl group, tridecenyl group, tetradecenyl group and the like. Among them, the above chain aliphatic group is preferably a saturated chain aliphatic group, more preferably a saturated straight-chain aliphatic group. Further, from the viewpoint of obtaining heat aging resistance, the above chain aliphatic group preferably has 6 or more carbon atoms, more preferably 7 or more carbon atoms, still more preferably 8 or more carbon atoms, and preferably 12 or less carbon atoms, more preferably 10 or less carbon atoms, still more preferably 9 or less carbon atoms. The above chain aliphatic group may be only one kind or two or more kinds. The above chain aliphatic group is particularly preferably at least one selected from the group consisting of n-octyl group, isooctyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, n-decyl group, and isodecyl group, more preferably at least one selected from the group consisting of n-octyl group, isooctyl group, 2-ethylhexyl group, n-nonyl group, and isononyl group, and most preferably at least one selected from the group consisting of n-octyl group, isooctyl group, and 2-ethylhexyl group. Further, from the viewpoint of heat aging resistance, the polyimide resin (A) preferably has only a chain aliphatic group having 5 to 14 carbon atoms at the terminal, in addition to the terminal amino group and the terminal carboxy group. When having a group other than the above at the terminal, the content thereof is preferably 10 mol% or less, more preferably 5 mol% or less, based on the chain aliphatic group having 5 to 14 carbon atoms.

[0030] From the viewpoint of exhibiting excellent heat aging resistance, the content of the linear aliphatic group having 5 to 14 carbon atoms in the polyimide resin (A) is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, still more preferably 0.2 mol% or more, based on 100 mol% of the total repeating structural units constituting the polyimide resin (A). Further, in order to ensure a sufficient molecular weight and obtain good mechanical properties, the content of the linear aliphatic group having 5 to 14 carbon atoms in the polyimide resin (A) is preferably 10 mol% or less, more preferably 6 mol% or less, still more preferably 3.5 mol% or less, based on 100 mol% of the total repeating structural units constituting the polyimide resin (A). The content of the linear aliphatic group having 5 to 14 carbon atoms in the polyimide resin (A) can be determined by depolymerizing the polyimide resin (A).

[0031] The polyimide resin (A) preferably has a melting point of 360 °C or lower and a glass transition temperature of 150 °C or higher. From the viewpoint of heat resistance, the melting point of the polyimide resin is more preferably 280 °C or higher, still more preferably 290 °C or higher, and from the viewpoint of exhibiting high moldability, it is preferably 345 °C or lower, more preferably 340 °C or lower, still more preferably 335 °C or lower. Also, from the viewpoint of heat resistance, the glass transition temperature of the polyimide resin (A) is more preferably 160 °C or higher, still more preferably 170 °C or higher, and from the viewpoint of exhibiting high moldability, it is preferably 250 °C or lower, more preferably 230 °C or lower, still more preferably 200 °C or lower. Both the melting point and the glass transition temperature of the polyimide resin can be measured by a differential scanning calorimeter. Further, from the viewpoints of improving crystallinity, heat resistance, mechanical strength, and chemical resistance of the polyimide resin (A), the heat quantity of the crystallization exothermic peak (hereinafter, also simply referred to as "crystallization heat quantity") observed when the polyimide resin is melted and then cooled at a cooling rate of 20 °C / min by differential scanning calorimetry measurement is preferably 5.0 mJ / mg or more, more preferably 10.0 mJ / mg or more, still more preferably 17.0 mJ / mg or more. The upper limit value of the crystallization heat quantity is not particularly limited, but is usually 45.0 mJ / mg or less. The melting point, glass transition temperature, and heat of crystallization of the polyimide resin can be specifically measured by the methods described in the examples.

[0032] The logarithmic viscosity of a 5% by mass sulfuric acid solution of the polyimide resin (A) at 30 °C is preferably in the range of 0.2 to 2.0 dL / g, more preferably 0.3 to 1.8 dL / g. If the logarithmic viscosity is 0.2 dL / g or more, sufficient mechanical strength can be obtained when the resulting polyimide resin composition is made into a molded article. If it is 2.0 dL / g or less, the moldability and handleability are improved. The logarithmic viscosity μ is determined from the following formula by measuring the flow times of concentrated sulfuric acid and the above polyimide resin solution at 30 °C using a Cannon-Fenske viscometer. μ = ln(ts / t0) / C t0: Flow time of concentrated sulfuric acid ts: Flow time of polyimide resin solution C: 0.5 (g / dL)

[0033] The weight average molecular weight Mw of the polyimide resin (A) is preferably in the range of 10,000 to 150,000, more preferably 15,000 to 100,000, still more preferably 20,000 to 80,000, even more preferably 30,000 to 70,000, and even more preferably 35,000 to 65,000. If the weight average molecular weight Mw of the polyimide resin (A) is 10,000 or more, the mechanical strength of the resulting molded article is improved. If it is 40,000 or more, the mechanical strength stability is improved. If it is 150,000 or less, the moldability is improved. The weight average molecular weight Mw of the polyimide resin (A) can be measured by gel permeation chromatography (GPC) using polymethyl methacrylate (PMMA) as a standard sample.

[0034] (Method for producing polyimide resin (A)) The polyimide resin (A) can be produced by reacting a tetracarboxylic acid component with a diamine component. The tetracarboxylic acid component contains at least one tetracarboxylic acid containing an aromatic ring and / or its derivative, and the diamine component contains at least one diamine containing an alicyclic hydrocarbon structure and a chain aliphatic diamine.

[0035] The tetracarboxylic acid containing at least one aromatic ring is preferably a compound in which four carboxy groups are directly bonded to the aromatic ring, and may contain an alkyl group in the structure. Further, the tetracarboxylic acid preferably has 6 to 26 carbon atoms. Examples of the tetracarboxylic acid include pyromellitic acid, 2,3,5,6-toluene tetracarboxylic acid, 3,3’,4,4’-benzophenone tetracarboxylic acid, 3,3’,4,4’-biphenyl tetracarboxylic acid, 1,4,5,8-naphthalene tetracarboxylic acid, etc. Among these, pyromellitic acid is more preferable.

[0036] Examples of derivatives of tetracarboxylic acids containing at least one aromatic ring include anhydrides or alkyl ester forms of tetracarboxylic acids containing at least one aromatic ring. The tetracarboxylic acid derivative preferably has 6 to 38 carbon atoms. Examples of the anhydride of tetracarboxylic acid include pyromellitic monoanhydride, pyromellitic dianhydride, 2,3,5,6-toluene tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, and the like. Examples of the alkyl ester form of tetracarboxylic acid include dimethyl pyromellitate, diethyl pyromellitate, dipropyl pyromellitate, diisopropyl pyromellitate, dimethyl 2,3,5,6-toluene tetracarboxylate, dimethyl 3,3',4,4'-diphenylsulfone tetracarboxylate, dimethyl 3,3',4,4'-benzophenone tetracarboxylate, dimethyl 3,3',4,4'-biphenyl tetracarboxylate, dimethyl 1,4,5,8-naphthalene tetracarboxylate, and the like. In the above alkyl ester form of tetracarboxylic acid, the alkyl group preferably has 1 to 3 carbon atoms.

[0037] As the tetracarboxylic acid and / or its derivative containing at least one aromatic ring, at least one compound selected from the above may be used alone, or two or more compounds may be used in combination.

[0038] The diamine containing at least one alicyclic hydrocarbon structure preferably has 6 to 22 carbon atoms. For example, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis(2-methylcyclohexylamine), carbonyldiamine, limonenediamine, isophoronediamine, norbornanediamine, bis(aminomethyl)tricyclo[5.2.1.02,6 Decane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylpropane and the like are preferable. These compounds may be used alone, or two or more compounds selected therefrom may be used in combination. Among these, 1,3-bis(aminomethyl)cyclohexane can be preferably used. In addition, diamines containing an alicyclic hydrocarbon structure generally have structural isomers, but the ratio of the cis form / trans form is not limited.

[0039] The chain aliphatic diamine may be linear or branched, and preferably has 5 to 16 carbon atoms, more preferably 6 to 14 carbon atoms, and even more preferably 7 to 12 carbon atoms. Further, if the carbon number of the chain portion is 5 to 16, it may contain an ether bond therein. Examples of the chain aliphatic diamine include 1,5-pentamethylenediamine, 2-methylpentane-1,5-diamine, 3-methylpentane-1,5-diamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine, 2,2'-(ethylenedioxy)bis(ethylamine) and the like are preferable. The chain aliphatic diamine may be used alone or as a mixture of two or more. Among these, chain aliphatic diamines having 8 to 10 carbon atoms can be preferably used, and at least one selected from the group consisting of 1,8-octamethylenediamine and 1,10-decamethylenediamine can be preferably used.

[0040] When producing the polyimide resin (A), the molar ratio of the charged amount of the diamine containing at least one alicyclic hydrocarbon structure to the total amount of the diamine containing at least one alicyclic hydrocarbon structure and the linear aliphatic diamine is preferably 20 to 70 mol%. The molar amount is preferably 25 mol% or more, more preferably 30 mol% or more, still more preferably 32 mol% or more, and from the viewpoint of exhibiting high crystallinity, preferably 60 mol% or less, more preferably 50 mol% or less, still more preferably less than 40 mol%, and still more preferably 35 mol% or less.

[0041] In addition, the diamine component may contain a diamine containing at least one aromatic ring. The number of carbon atoms of the diamine containing at least one aromatic ring is preferably 6 to 22. For example, ortho-xylylenediamine, meta-xylylenediamine, para-xylylenediamine, 1,2-diethynylbenzene diamine, 1,3-diethynylbenzene diamine, 1,4-diethynylbenzene diamine, 1,2-diaminobenzene, 1,3-diaminobenzene, 1,4-diaminobenzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl methane, α,α'-bis(4-aminophenyl)1,4-diisopropylbenzene, α,α'-bis(3-aminophenyl)-1,4-diisopropylbenzene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene, etc. may be mentioned.

[0042] In the above, the molar ratio of the charged amount of the diamine containing at least one aromatic ring to the total amount of the diamine containing at least one alicyclic hydrocarbon structure and the linear aliphatic diamine is preferably 25 mol% or less. On the other hand, the lower limit is not particularly limited as long as it exceeds 0 mol%. From the viewpoint of improving heat resistance, the molar ratio is preferably 5 mol% or more, more preferably 10 mol% or more. On the other hand, from the viewpoint of maintaining crystallinity, it is preferably 20 mol% or less, more preferably 15 mol% or less. Also, from the viewpoint of reducing the coloring of the polyimide resin, the molar ratio is preferably 12 mol% or less, more preferably 10 mol% or less, still more preferably 5 mol% or less, and even more preferably 0 mol%.

[0043] When producing the polyimide resin (A), the charging amount ratio of the tetracarboxylic acid component to the diamine component is preferably 0.9 to 1.1 mol of the diamine component with respect to 1 mol of the tetracarboxylic acid component.

[0044] Also, when producing the polyimide resin (A), in addition to the tetracarboxylic acid component and the diamine component, a terminal blocking agent may be mixed. As the terminal blocking agent, at least one selected from the group consisting of monoamines and dicarboxylic acids is preferable. The amount of the terminal blocking agent used may be an amount capable of introducing a desired amount of terminal groups into the polyimide resin (A), and is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, and still more preferably 0.002 to 0.035 mol with respect to 1 mol of the tetracarboxylic acid and / or its derivative. Examples of the monoamine terminal blocking agent include methylamine, ethylamine, propylamine, butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, laurylamine, n-tridecylamine, n-tetradecylamine, isopentylamine, neopentylamine, 2-methylpentylamine, 2-methylhexylamine, 2-ethylpentylamine, 3-ethylpentylamine, isooctylamine, 2-ethylhexylamine, 3-ethylhexylamine, isononylamine, 2-ethyloctylamine, isodecylamine, isododecylamine, isotridecylamine, isotetradecylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, and the like. As the dicarboxylic acid terminal capping agent, dicarboxylic acids are preferred, and a part of them may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. may be mentioned. Among these, phthalic acid and phthalic anhydride are preferred. These terminal capping agents may be used alone or in combination of two or more. Among them, monoamine terminal capping agents are preferred. From the viewpoint of introducing the above-mentioned linear aliphatic group having 5 to 14 carbon atoms at the terminal of the polyimide resin (A) to improve heat aging resistance, a monoamine having a linear aliphatic group having 5 to 14 carbon atoms is more preferred, and a monoamine having a saturated linear aliphatic group having 5 to 14 carbon atoms is even more preferred. The above linear aliphatic group preferably has 6 or more carbon atoms, more preferably 7 or more carbon atoms, still more preferably 8 or more carbon atoms, preferably 12 or less carbon atoms, more preferably 10 or less carbon atoms, still more preferably 9 or less carbon atoms. If the carbon number of the linear aliphatic group of the monoamine is 5 or more, it is preferable because the monoamine is difficult to volatilize during the production of the polyimide resin (A). The terminal capping agent is particularly preferably at least one selected from the group consisting of n-octylamine, isooctylamine, 2-ethylhexylamine, n-nonylamine, isononylamine, n-decylamine, and isodecylamine, more preferably at least one selected from the group consisting of n-octylamine, isooctylamine, 2-ethylhexylamine, n-nonylamine, and isononylamine, and most preferably at least one selected from the group consisting of n-octylamine, isooctylamine, and 2-ethylhexylamine.

[0045] As a polymerization method for producing the polyimide resin (A), known polymerization methods can be applied and are not particularly limited. For example, solution polymerization, melt polymerization, solid-phase polymerization, suspension polymerization method, etc. can be mentioned. Among these, suspension polymerization under high-temperature conditions using an organic solvent is particularly preferred. When performing suspension polymerization under high-temperature conditions, it is preferably carried out at 150°C or higher, more preferably at 180 - 250°C. The polymerization time can be appropriately changed depending on the monomers used, but it is preferably carried out for about 0.1 - 6 hours.

[0046] As a method for producing the polyimide resin (A), it preferably includes a step of reacting the tetracarboxylic acid component and the diamine component in the presence of a solvent containing an alkylene glycol-based solvent represented by the following formula (I). Thereby, a powdery polyimide resin excellent in handleability can be obtained.

Chemical formula

[0047] Ra1 in the formula (I) is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group. Ra2 in formula (I) is a linear alkylene group having 2 to 6 carbon atoms, preferably a linear alkylene group having 2 to 3 carbon atoms, and more preferably an ethylene group. n in formula (I) is an integer of 1 to 3, preferably 2 or 3. Specific examples of the alkylene glycol-based solvent include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether (alias: 2-(2-methoxyethoxy)ethanol), triethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether (alias: 2-(2-ethoxyethoxy)ethanol), ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol, 1,3-propanediol, and the like. These solvents may be used alone, or two or more solvents selected from these may be used in combination. Among these solvents, 2-(2-methoxyethoxy)ethanol, triethylene glycol monomethyl ether, 2-(2-ethoxyethoxy)ethanol, and 1,3-propanediol are preferred, and 2-(2-methoxyethoxy)ethanol and 2-(2-ethoxyethoxy)ethanol are more preferred.

[0048] The content of the alkylene glycol-based solvent in the solvent is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 75% by mass or more, and even more preferably 90% by mass or more. The solvent may consist only of the alkylene glycol-based solvent. When the solvent contains the alkylene glycol-based solvent and other solvents, specific examples of the "other solvents" include water, benzene, toluene, xylene, acetone, hexane, heptane, chlorobenzene, methanol, ethanol, n-propanol, isopropanol, butanol, pentanol, hexanol, heptanol, octanol, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylcaprolactam, hexamethylphosphoramide, tetramethylene sulfone, dimethyl sulfoxide, o-cresol, m-cresol, p-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglyme, triglyme, tetraglyme, dioxane, γ-butyrolactone, dioxolane, cyclohexanone, cyclopentanone, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, dibromomethane, tribromomethane, 1,2-dibromoethane, 1,1,2-tribromoethane, etc. These solvents may be used alone, or two or more solvents selected from these may be used in combination.

[0049] As a preferred production method of the polyimide resin (A), for example, a solution (a) obtained by including a tetracarboxylic acid component in a solvent containing the alkylene glycol-based solvent and a solution (b) obtained by including a diamine component in a solvent containing the alkylene glycol-based solvent are separately prepared, and then the solution (b) is added to the solution (a) or the solution (a) is added to the solution (b) to prepare a solution (c) containing polyamic acid. Next, by heating the solution (c), the polyamic acid is imidized and polyimide resin powder is precipitated in the solution (c) to synthesize the polyimide resin (A). The reaction between the tetracarboxylic acid component and the diamine component can be carried out either under normal pressure or under pressure, but it is preferably carried out under normal pressure because a pressure-resistant container is not required under normal pressure. When using a terminal blocking agent, it is preferable to mix solution (a) and solution (b), mix the terminal blocking agent into this mixed solution to prepare solution (c) containing polyamic acid, and then heat the said solution (c). It is more preferable to add the terminal blocking agent after adding solution (b) to solution (a) to prepare solution (c) containing polyamic acid, and then heat the said solution (c).

[0050] Also, from the viewpoint of reducing the amount of by-products in the polyimide resin (A), the method for producing the polyimide resin (A) is such that the tetracarboxylic acid component contains a tetracarboxylic dianhydride; the step of reacting the said tetracarboxylic acid component and diamine component is to add solution (b) containing the diamine component and the alkylene glycol-based solvent to solution (a) containing the tetracarboxylic acid component and the alkylene glycol-based solvent to prepare solution (c) containing polyamic acid (step (i)), and heating the said solution (c) to imidize the polyamic acid and precipitate polyimide resin powder in the said solution (c) to obtain polyimide resin powder (step (ii)); in the said step (i), it is preferable to add solution (b) to solution (a) such that the addition amount of the said diamine component per unit time with respect to 1 mol of the tetracarboxylic acid component is 0.1 mol / min or less.

[0051] <Metal phosphinate-based flame retardant (B)> The polyimide resin composition of the present invention contains a polyimide resin (A) and a metal phosphinate-based flame retardant (B). By using a metal phosphinate-based flame retardant (B) as a flame retardant for the polyimide resin (A) having the specific structure, a high flame retardancy of V-0 level can be imparted in the UL94 standard. Also, a polyimide resin composition and a molded article with good appearance can be obtained, in which bleeding out of the flame retardant, coloring, and whitening during melt kneading and molding processes are less likely to occur. Since the polyimide resin (A) has thermoplasticity and high heat resistance, the melt kneading and molding of the resin composition containing the polyimide resin (A) are preferably carried out in the range of 290 to 350 °C. The metal phosphinate-based flame retardant (B) (hereinafter also simply referred to as "flame retardant (B)") is stable in that bleeding out, thermal decomposition, coloring, whitening, etc. of the flame retardant (B) hardly occur even in the above temperature range, and it also has excellent dispersibility in the polyimide resin (A). Therefore, it is considered that high flame retardancy and good appearance can be achieved when blended in the polyimide resin composition and the molded article. In addition, generally, an addition amount of the flame retardant to the resin of 10% by mass or more is recommended. However, since the metal phosphinate-based flame retardant (B) has high dispersibility in the polyimide resin (A), it can exhibit flame retardancy even at an addition amount of less than 10% by mass. Furthermore, when using the flame retardant (B), a V-0 level of flame retardancy can be achieved without using a drip inhibitor such as polytetrafluoroethylene in combination.

[0052] The flame retardant (B) is a metal salt of phosphinic acid, and is preferably a salt of at least one metal selected from the group consisting of Mg, Ca, Al, Zn, Ti, Sn, Zr, and Fe. More preferably, the metal is at least one selected from the group consisting of Mg, Ca, and Al, and even more preferably Al.

[0053] From the viewpoint of achieving both high flame retardancy and good appearance when blended in the polyimide resin composition and the molded article, the flame retardant (B) is more preferably a compound represented by the following formula (i).

Chemical formula

[0054] In the formula (i), R' and R" each independently represent a hydrocarbon group having 1 to 12 carbon atoms. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, and the like. Examples of the alkyl group include alkyl groups having 1 to 12 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, a lauryl group, an isopropyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 2-methylpentyl group, a 2-methylhexyl group, a 2-ethylpentyl group, a 3-ethylpentyl group, an isooctyl group, a 2-ethylhexyl group, a 3-ethylhexyl group, an isononyl group, a 2-ethyloctyl group, an isodecyl group, an isododecyl group, and the like. Examples of the cycloalkyl group include cycloalkyl groups having 5 to 12 carbon atoms such as a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a cyclodecanyl group, and the like. Examples of the alkenyl group include alkenyl groups having 2 to 12 carbon atoms such as a vinyl group, an allyl group, a butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-heptenyl group, a 2-heptenyl group, a 1-octenyl group, a 2-octenyl group, a nonenyl group, a decenyl group, a dodecenyl group, and the like. Examples of the aryl group include aryl groups having 6 to 12 carbon atoms such as a phenyl group, a toluyl group, a biphenyl group, a naphthyl group, and the like. Examples of the aralkyl group include aralkyl groups having 7 to 12 carbon atoms such as a benzyl group, a phenylethyl group, a phenylpropyl, and other aralkyl groups. Among the above, it is preferable that R' and R" are alkyl groups. The number of carbon atoms of the alkyl group is preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 3. R' and R" may be the same or different, but it is preferable that they are the same.

[0055] In the formula (i), M is a metal atom, and it is preferably at least one selected from the group consisting of Mg, Ca, Al, Zn, Ti, Sn, Zr, and Fe. More preferably, M is at least one selected from the group consisting of Mg, Ca, and Al, and still more preferably, M is Al.

[0056] As the flame retardant (B), a compound in which R' and R” in the formula (i) are alkyl groups having 1 to 12 carbon atoms and M is Al (aluminum dialkylphosphinate) is preferable. In this case, p in the formula (i) is 3. More preferable embodiments of R' and R” are the same as described above. More preferably, the flame retardant (B) is a compound in which R' and R” in the formula (i) are ethyl groups and M is Al (aluminum diethylphosphinate). Aluminum diethylphosphinate is a compound represented by the following structural formula (ii).

Chemical formula

[0057] Since the flame retardant (B) is a metal phosphinate salt, it is usually a solid compound, and from the viewpoint of dispersibility in the polyimide resin (A), it is preferably in powder form. Also, from the viewpoint of achieving both high flame retardancy and good appearance, it is preferable that the particle size of the flame retardant (B) is small. From the above viewpoints, the particle size (D50) of the flame retardant (B) is preferably 40 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less, even more preferably 10 μm or less, and even more preferably 5 μm or less. When the particle size (D50) of the flame retardant (B) is 40 μm or less, particularly 10 μm or less, higher flame retardancy and good appearance can be achieved simultaneously in the resulting polyimide resin composition and molded article. Also, the particle size (D50) of the flame retardant (B) is preferably 0.1 μm or more, more preferably 0.5 μm or more, and still more preferably 1 μm or more. The particle size (D50) of the flame retardant (B) can be measured by a laser diffraction particle size distribution analyzer, and specifically, it can be measured by the method described in the examples.

[0058] From the viewpoint of imparting high flame retardancy, the phosphorus content of the flame retardant (B) is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 20% by mass or more. Also, from the viewpoint of dispersibility in the polyimide resin (A) and obtaining good appearance in the polyimide resin composition and molded article, the phosphorus content of the flame retardant (B) is preferably 40% by mass or less.

[0059] The flame retardant (B) can be produced by a known method. Also, a commercially available metal phosphinate-based flame retardant can be used as the flame retardant (B). Examples of the commercially available metal phosphinate-based flame retardant include "EXOLIT OP1230", "EXOLIT OP1240", "EXOLIT OP1400", "EXOLIT OP930", "EXOLIT OP935", "EXOLIT OP945TP", etc. manufactured by Clariant Chemicals (Japan) Ltd. The flame retardant (B) can be used alone or in combination of two or more.

[0060] The content of the metal phosphinate-based flame retardant (B) in the polyimide resin composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, and still more preferably 1.0 to 12% by mass. If the content of the metal phosphinate-based flame retardant (B) is 0.1% by mass or more, the effect of improving flame retardancy can be obtained, and if it is 20% by mass or less, good appearance can be maintained.

[0061] <Additive> Additives such as fillers, matting agents, nucleating agents, plasticizers, antistatic agents, anti-coloring agents, anti-gelling agents, coloring agents, sliding property improvers, antioxidants, conductive agents, and resin modifiers can be blended into the polyimide resin composition of the present invention as necessary. Although there is no particular limitation on the blending amount of the above additives, from the viewpoint of exhibiting the effects of the additives while maintaining the physical properties derived from the polyimide resin (A), it is usually 50% by mass or less, preferably 0.0001 to 30% by mass, more preferably 0.001 to 15% by mass, and still more preferably 0.01 to 10% by mass in the polyimide resin composition.

[0062] In addition, in the polyimide resin composition of the present invention, other resins other than the polyimide resin (A) can be blended as long as their properties are not inhibited. As the other resin, a thermoplastic resin with high heat resistance is preferable. For example, polyamide resin, polyester resin, polyimide resin other than the polyimide resin (A), polycarbonate resin, polyetherimide resin, polyamideimide resin, polyphenylene etherimide resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyarylate resin, liquid crystal polymer, polyetheretherketone resin, polyetherketone resin, polyetherketoneketone resin, polyetheretherketoneketone resin, polybenzimidazole resin, etc. can be mentioned. Among these, from the viewpoints of heat resistance, moldability, strength, and solvent resistance, one or more selected from the group consisting of polyetherimide resin, polyphenylene sulfide resin, and polyetheretherketone resin are preferable, and from the viewpoint of obtaining high flame retardancy, polyphenylene sulfide resin is more preferable. When the polyimide resin (A) and other resins are used in combination, the blending ratio is not particularly limited as long as the properties of the polyimide resin composition are not inhibited.

[0063] However, from the viewpoint of obtaining the effects of the present invention, the total content of the polyimide resin (A) and the flame retardant (B) in the polyimide resin composition of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more. The upper limit is 100% by mass.

[0064] The polyimide resin composition of the present invention can take any form, but is preferably in the form of pellets. Since the polyimide resin composition of the present invention and the polyimide resin (A) used therein have thermoplasticity, for example, after adding a polyimide resin (A), a flame retardant (B), and various optional components as required and dry blending them, they are melt-kneaded in an extruder to extrude strands, and the strands can be pelletized by cutting. Further, by introducing the pellets into various molding machines and performing thermoforming by the method described below, a molded body having a desired shape can be easily manufactured. In the production process and thermoforming process of the above pellets, bleeding out or thermal decomposition, coloring, whitening, etc. of the flame retardant usually occur easily. However, in the polyimide resin composition of the present invention, these problems hardly occur, and a good appearance can be maintained.

[0065] <Flammability> The polyimide resin composition of the present invention complies with the UL94 standard, which is the flammability test standard for plastic materials issued by Underwriters Laboratories, and has a high flame retardancy of V-0 level when a combustion test is performed by the vertical combustion test method. Specifically, the flame retardancy can be evaluated by the method described in the examples.

[0066] [Molded body] The present invention provides a molded body containing the above polyimide resin composition. Since the polyimide resin composition of the present invention has thermoplasticity, the molded body of the present invention can be easily manufactured by thermoforming. Examples of the thermoforming method include injection molding, extrusion molding, blow molding, hot press molding, vacuum molding, pressure air molding, laser molding, welding, and adhesion. Any method can be used as long as it is a molding method that passes through a hot melting process. Thermoforming is preferable because it can be performed without setting the molding temperature to a high temperature exceeding, for example, 400°C. Among them, when performing injection molding, it is preferable because it can be molded without setting the molding temperature and the mold temperature during molding to a high temperature. For example, in injection molding, the molding temperature is preferably 400°C or lower, more preferably 360°C or lower, and the mold temperature is preferably 260°C or lower, more preferably 220°C or lower for molding.

[0067] As a method for manufacturing a molded body, it is preferable to have a step of thermally molding a polyimide resin composition at 290 to 350°C. Although thermal molding at temperatures exceeding 350°C to 390°C is also possible, from the viewpoint of suppressing the deterioration of the polyimide resin (A), other resin components, and various fillers, it is preferable to perform thermal molding at a temperature of 350°C or lower. Specific procedures include, for example, the following methods. First, a flame retardant (B) and various optional components as required are added to the polyimide resin (A) and dry-blended, and then this is introduced into an extruder and preferably melted at 290 to 350°C for melt-kneading and extrusion in the extruder to produce pellets. Alternatively, the polyimide resin (A) may be introduced into an extruder and preferably melted at 290 to 350°C, and the flame retardant (B) and various optional components as required may be introduced here for melt-kneading with the polyimide resin (A) in the extruder and then extruded to produce the aforementioned pellets. After drying the above pellets, they are introduced into various molding machines and preferably thermally molded at 290 to 350°C to produce a molded body having a desired shape. Since the polyimide resin composition of the present invention can perform thermoforming such as extrusion molding at a relatively low temperature of 290 to 350°C, it has excellent molding processability and can easily produce a molded product having a desired shape. The temperature during thermoforming is preferably 310 to 350°C.

[0068] Since the polyimide resin composition of the present invention is thermoplastic and has molding processability, and can achieve both high flame retardancy and good appearance, it can be applied to, for example, various industrial members such as automobiles, railways, and aviation, members for home appliances, or their housings, etc. Specifically, it can be applied to gears, bearings, cutting members, screws, nuts, packings, inspection IC sockets, belts, coating materials for electric wires, coverlay films, members for semiconductor manufacturing equipment, medical instruments, coating materials for fishing rods and reels, stationery, carbon UD tapes, heat insulation materials, etc. Also, since the molded body has good mechanical properties and heat resistance, it can also be applied to various metal replacements including aluminum alloys and magnesium alloys.

Examples

[0069] Next, examples will be given to explain the present invention in more detail, but the present invention is not limited thereto. Also, various measurements and evaluations in each production example, example, and reference example were conducted as follows.

[0070] <Infrared spectroscopic analysis (IR measurement)> IR measurement of the polyimide resin was performed using "JIR-WINSPEC50" manufactured by JEOL Ltd.

[0071] <Logarithmic viscosity μ> After drying the polyimide resin at 190 to 200 °C for 2 hours, a polyimide resin solution prepared by dissolving 0.100 g of the polyimide resin in 20 mL of concentrated sulfuric acid (96%, manufactured by Kanto Chemical Co., Inc.) was used as a measurement sample, and the measurement was performed at 30 °C using a Cannon-Fenske viscometer. The logarithmic viscosity μ was determined by the following formula. μ = ln(ts / t0) / C t0: Flow time of concentrated sulfuric acid ts: Flow time of the polyimide resin solution C: 0.5 g / dL

[0072] <Melting point, glass transition temperature, crystallization temperature, heat of crystallization> The melting point Tm, glass transition temperature Tg, crystallization temperature Tc, and heat of crystallization ΔHm of the polyimide resin or polyimide resin composition were measured using a differential scanning calorimeter (DSC-6220 manufactured by SII NanoTechnology Inc.). Under a nitrogen atmosphere, a thermal history under the following conditions was imposed on the polyimide resin or polyimide resin composition. The conditions of the thermal history were the first heating (heating rate: 10 °C / min), then cooling (cooling rate: 20 °C / min), and then the second heating (heating rate: 10 °C / min). The melting point Tm was determined by reading the peak top value of the endothermic peak observed during the second heating. The glass transition temperature Tg was determined by reading the value observed during the second heating. The crystallization temperature Tc was determined by reading the peak top value of the exothermic peak observed during cooling. Also, the heat of crystallization ΔHm (mJ / mg) was calculated from the area of the exothermic peak observed during cooling.

[0073] <Semicrystallization time> The semicrystallization time of the polyimide resin was measured using a differential scanning calorimeter (DSC-6220 manufactured by SII NanoTechnology Inc.). The measurement conditions for the polyimide resin with a semicrystallization time of 20 seconds or less were as follows: under a nitrogen atmosphere, held at 420 °C for 10 minutes to completely melt the polyimide resin, and then, when performing a rapid cooling operation at a cooling rate of 70 °C / min, the time taken from the appearance of the crystallization peak to reaching the peak top was calculated and determined.

[0074] <Weight average molecular weight> The weight average molecular weight (Mw) of the polyimide resin was measured under the following conditions using a gel permeation chromatography (GPC) measurement device "Shodex GPC-101" manufactured by Showa Denko K.K. Column: Shodex HFIP-806M Mobile phase solvent: HFIP containing 2 mM sodium trifluoroacetate Column temperature: 40 °C Mobile phase flow rate: 1.0 mL / min Sample concentration: Approximately 0.1 mass% Detector: IR detector Injection volume: 100 μm Calibration curve: Standard PMMA

[0075] <Particle size (D50)> The particle size (D50) of the flame retardant was determined by laser diffraction particle size distribution measurement. As the measurement device, a laser diffraction light scattering particle size distribution analyzer "LMS-2000e" manufactured by Malvern was used. Water was used as the dispersion medium, and the measurement was performed under ultrasonic conditions such that the flame retardant was sufficiently dispersed. The measurement range was set to 0.02 to 2000 μm.

[0076] <Flexural strength and flexural modulus> Using the polyimide resin composition obtained in each example, a molded body with dimensions of 80 mm × 10 mm × 4 mm in thickness as defined in ISO 316 was produced and used for measurement. Using a bend graph (manufactured by Toyo Seiki Seisakusho Co., Ltd.), in accordance with ISO 178, a bending test was conducted at a temperature of 23°C and a test speed of 2 mm / min, and the bending strength and bending modulus were measured.

[0077] <Heat distortion temperature (HDT)> Using the polyimide resin composition obtained in each example, a molded body with dimensions of 80 mm × 10 mm × 4 mm in thickness was produced and used for measurement. Using an HDT test apparatus "Auto-HDT3D-2" (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the heat distortion temperature was measured under the conditions of a distance between supports of 64 mm, a load of 1.80 MPa, and a heating rate of 120°C / hour.

[0078] <Flammability> Using the polyimide resin composition obtained in each example, a molded body with dimensions of 80 mm × 10 mm × 4 mm in thickness was produced and used for flammability evaluation. In accordance with the UL94 standard, which is the flammability test standard for plastic materials issued by Underwriters Laboratories, a combustion test was conducted on the above-mentioned molded body by the vertical burning test method (n = 5), and the flammability rank (V-0, V-1, V-2) was determined. If the flammability rank is V-0, it means that the flammability is good. Also, if the flammability does not reach V-2, it was regarded as "out of specification". For the polyimide resin compositions of Examples 4 to 7, a molded body with dimensions of 127 mm × 13 mm × 1.6 mm in thickness was produced and used for flammability evaluation. For the polyimide resin compositions of Examples 4 to 6, a molded body with dimensions of 127 mm × 13 mm × 0.8 mm in thickness was produced and used for flammability evaluation.

[0079] <Appearance> Using the polyimide resin composition obtained in each example, a molded body with dimensions of 80 mm × 10 mm × 4 mm in thickness was produced, and its appearance was visually observed and evaluated according to the following criteria. AA: No whitening or browning, good appearance A: A part of the molded body is whitened, or browning is observed during the molding process, but there is substantially no problem. B: Glittering or browning is observed throughout the molded body. C: Bleed-out of the flame retardant or severe browning occurs, resulting in poor appearance

[0080] <Strand extrudability> The strand extrudability of the polyimide resin composition was evaluated according to the following criteria. A: Maintains a constant strand diameter and can be continuously extruded without breaking B: Pulse of the strand is observed and the diameter becomes unstable, or weak smoke emission is observed, but it can be continuously extruded without breaking C: Strand breakage or strong smoke emission occurs, making it difficult to continuously extrude

[0081] [Production Example 1] Production of Polyimide Resin 1 Into a Dean-Stark apparatus, a Liebig condenser, a thermocouple, and a 2 L separable flask equipped with four paddle blades, 500 g of 2-(2-methoxyethoxy)ethanol (manufactured by Nippon Emulsifier Co., Ltd.) and 218.12 g (1.00 mol) of pyromellitic dianhydride (manufactured by Mitsubishi Gas Chemical Company, Inc.) were introduced. After flowing nitrogen, the mixture was stirred at 150 rpm to form a uniform suspension. On the other hand, using a 500 mL beaker, 49.79 g (0.35 mol) of 1,3-bis(aminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., cis / trans ratio = 7 / 3) and 93.77 g (0.65 mol) of 1,8-octamethylenediamine (manufactured by Kanto Chemical Co., Inc.) were dissolved in 250 g of 2-(2-methoxyethoxy)ethanol to prepare a mixed diamine solution. This mixed diamine solution was gradually added using a plunger pump. Although heat generation occurred during the dropping, the internal temperature was adjusted to be maintained between 40 and 80 °C. Nitrogen was flowed throughout the dropping of the mixed diamine solution, and the rotation speed of the stirring blade was 250 rpm. After the dropping was completed, 130 g of 2-(2-methoxyethoxy)ethanol and 1.284 g (0.0100 mol) of n-octylamine (manufactured by Kanto Chemical Co., Inc.), which is a terminal blocking agent, were added and further stirred. At this stage, a pale yellow polyamic acid solution was obtained. Next, after setting the stirring speed to 200 rpm, the polyamic acid solution in the 2 L separable flask was heated to 190 °C. During the process of heating up, precipitation of polyimide resin powder and dehydration accompanying imidization were confirmed when the liquid temperature was between 120 and 140 °C. After holding at 190 °C for 30 minutes, it was allowed to cool to room temperature and then filtered. The obtained polyimide resin powder was washed and filtered with 300 g of 2-(2-methoxyethoxy)ethanol and 300 g of methanol, and then dried in a dryer at 180 °C for 10 hours to obtain 317 g of powder of polyimide resin 1. When the IR spectrum of polyimide resin 1 was measured, characteristic absorptions of the imide ring were observed at ν(C=O) 1768, 1697 (cm -1 -1). The logarithmic viscosity was 1.30 dL / g, Tm was 323 °C, Tg was 184 °C, Tc was 266 °C, the heat of crystallization was 21.0 mJ / mg, the half-crystallization time was 20 seconds or less, and Mw was 55,000.

[0082] Table 1 shows the composition and evaluation results of the polyimide resin in Production Example 1. The mol% of the tetracarboxylic acid component and the diamine component in Table 1 are values calculated from the charged amounts of the respective components during the production of the polyimide resin.

[0083]

Table 1

[0084] The abbreviations in Table 1 are as follows. ·PMDA; Pyromellitic dianhydride ·1,3-BAC; 1,3-Bis(aminomethyl)cyclohexane ·OMDA; 1,8-Octamethylenediamine

[0085] Examples 1 to 9, Comparative Examples 1 to 10 (Production and Evaluation of Polyimide Resin Compositions) The polyimide resin 1 obtained in Production Example 1, the flame retardant shown in Table 2, and other components were thoroughly mixed by dry blending. The obtained mixed powder was extruded using a lab plastomill (manufactured by Toyo Seiki Seisaku-sho, Ltd.) as an extruder at a barrel temperature of 350°C and a screw rotation speed of 70 rpm. The strand extruded from the extruder was air-cooled and then pelletized using a pelletizer ("Fan Cutter FC-Mini-4 / N" manufactured by Hoshi Plastics Co., Ltd.). The obtained pellets (polyimide resin composition) were dried at 190°C for 10 hours and then used for injection molding. Injection molding was performed using an injection molding machine ("ROBOSHOT α-S30iA" manufactured by Fanuc Corporation) at a barrel temperature of 350°C, a mold temperature of 200°C, and a molding cycle of 50 seconds to produce molded bodies of a predetermined shape for various evaluations. Using the obtained pellets (polyimide resin composition) or the produced molded bodies, various evaluations were performed by the aforementioned methods. The results are shown in Table 2.

[0086]

Table 2

[0087] The details of each component shown in Table 2 are as follows. <Polyimide resin (A)> (A1) Polyimide resin 1 obtained in Production Example 1, Mw: 55,000 <Flame retardant (B)> (B1) EXOLIT OP1230: Metal phosphinate-based flame retardant (aluminum diethylphosphinate) represented by the following structural formula (ii), manufactured by Clariant Chemicals (Japan) Ltd., particle size (D50): 27 μm, phosphorus content: 23% by mass

Chemical formula

[0088] (B2) EXOLIT OP1240: Metal phosphinate-based flame retardant, manufactured by Clariant Chemicals (Japan) Ltd., particle size (D50): 31 μm, phosphorus content: 23% by mass (B3) EXOLIT OP1400: Metal phosphinate-based flame retardant, manufactured by Clariant Chemicals (Japan) Ltd., particle size (D50): 20 μm, phosphorus content: 25% by mass (B4) EXOLIT OP930: Metal phosphinate-based flame retardant (aluminum diethylphosphinate) represented by the above structural formula (ii), manufactured by Clariant Chemicals (Japan) Ltd., particle size (D50): 4 μm, phosphorus content: 23% by mass (B5) EXOLIT OP945TP: Metal phosphinate-based flame retardant (aluminum diethylphosphinate) represented by the above structural formula (ii), manufactured by Clariant Chemicals (Japan) Ltd., particle size (D50): 1.3 μm, phosphorus content: 23% by mass

[0089] <Flame retardant other than (B)> (b1) PX-202: Aromatic phosphate ester represented by the following structural formula, manufactured by Daihachi Chemical Industry Co., Ltd.

Chemical formula

[0090] (b2) Polyflon MPA FA-500H: Polytetrafluoroethylene, manufactured by Daikin Industries, Ltd. (b3)PHOSMEL - 200: Polyphosphoric acid - melamine - based salt compound, manufactured by Nissan Chemical Industries, Ltd. (b4)EXOLIT HP7010: Brominated polystyrene, manufactured by Clariant Chemicals (Japan) Ltd.

[0091] <Other components> Glass fiber: "ECS 03 T - 786H" manufactured by Nippon Electric Glass Co., Ltd., average fiber diameter 10.5 μm, average fiber length 3 mm Talc: "Nano Ace D - 800" manufactured by Nippon Talc Co., Ltd., average particle size (D50): 0.8 μm Antioxidant: Hindered phenol - based antioxidant, "IRGANOX 1010" manufactured by BASF Japan Ltd.

[0092] As shown in Table 2, the polyimide resin compositions of Examples 1 to 9 containing a predetermined polyimide resin (A) and a flame retardant (B) exhibit high flame retardancy, and the appearance and strand extrudability of the molded body are also good. In addition, the mechanical properties and heat resistance were also good. On the other hand, in the polyimide resin compositions of Comparative Examples 1 to 10, it was not possible to achieve both flame retardancy and good appearance.

Industrial Applicability

[0093] The polyimide resin composition of the present invention is excellent in moldability and can achieve both high flame retardancy and good appearance. The polyimide resin composition of the present invention can be applied to, for example, various industrial members such as automobiles, railways, and aviation, members for home appliances, or their housings, etc. Specifically, it can be applied to gears, bearings, cutting members, screws, nuts, packings, inspection IC sockets, cover films, members for semiconductor manufacturing equipment, medical instruments, cover materials for fishing rods and reels, stationery, carbon UD tapes, heat insulating materials, etc. In addition, since the molded body also has good mechanical properties and heat resistance, it can also be applied to various metal replacements including aluminum alloys and magnesium alloys.

Claims

1. A thermoplastic polyimide resin composition containing a repeating structural unit represented by the following formula (1) and a repeating structural unit represented by the following formula (2), wherein the content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is 20 to 70 mol%, and a metal phosphinate flame retardant (B), wherein the particle size (D50) of the metal phosphinate flame retardant (B) is 10 μm or less, wherein the total content of the thermoplastic polyimide resin (A) and the metal phosphinate flame retardant (B) in the thermoplastic polyimide resin composition is 80% by mass or more, and the content of the metal phosphinate flame retardant (B) in the thermoplastic polyimide resin composition is 1.0 to 12% by mass. 【Chemical 1】 (R １ is a divalent group having 6 to 22 carbon atoms and containing at least one alicyclic hydrocarbon structure. R ２ is a divalent linear aliphatic group having 5 to 16 carbon atoms. X １ and X ２ are each independently a tetravalent group having 6 to 22 carbon atoms and containing at least one aromatic ring.)

2. The thermoplastic polyimide resin composition according to Claim 1, wherein in the thermoplastic polyimide resin (A), the content ratio of the repeating structural unit of the formula (1) to the total of the repeating structural unit of the formula (1) and the repeating structural unit of the formula (2) is 20 mol% or more and less than 40 mol%.

3. The thermoplastic polyimide resin composition according to Claim 1 or 2, wherein the metal phosphinate flame retardant (B) is a salt of at least one metal selected from the group consisting of Mg, Ca, Al, Zn, Ti, Sn, Zr, and Fe.

4. The thermoplastic polyimide resin composition according to any one of Claims 1 to 3, wherein the metal phosphinate flame retardant (B) is a compound represented by the following formula (i). 【Chemical Formula 2】 (R' and R'' are each independently a hydrocarbon group having 1 to 12 carbon atoms, M is a metal atom, and p is the valence of the metal atom represented by M.)

5. A molded article containing the thermoplastic polyimide resin composition according to any one of Claims 1 to 4.

Images